基本情報

所属

• 触媒科学研究所　触媒材料研究部門

職名

• 教授

学位

• 博士（工学）（名古屋大学）

ホームページURL

http://www.cat.hokudai.ac.jp/shimizu/

J-Global ID

• 200901093370051913

研究キーワード

• 反応機構   クラスター   グリーンケミストリ   固体酸触媒   X線吸収スペクトル   有機合成   複合化触媒   触媒設計   ディーゼル排ガス   NO選択還元反応   メソポーラスシリカ   固体触媒   低温燃焼   触媒構造解析   貴金属   酸化物触媒   銀ナノクラスター   触媒劣化   ディーゼル自動車排ガス   尿素脱硝法   環境触媒   ディーゼル自動車   アルミネート   in-situ赤外分光法   白金代替触媒   アミン   自動車排ガス浄化   有機分子触媒   赤外分光   スルホン酸   自動車触媒   グリーンケミストリー   銀触媒   金属ナノクラスター   Automotive catalyst   Green organic synthesis   Silver catalyst   Metal cluster   

研究分野

• ナノテク・材料 / グリーンサステイナブルケミストリー、環境化学
• ナノテク・材料 / エネルギー化学
• ものづくり技術（機械・電気電子・化学工学） / 触媒プロセス、資源化学プロセス

担当教育組織

•  修士課程　総合化学院
•  博士課程　総合化学院

職歴

• 2015年10月 - 現在 北海道大学 触媒科学研究所 教授
• 2015年04月 - 2015年09月 北海道大学 触媒化学研究センター 教授
• 2010年10月 - 2015年03月 北海道大学 触媒化学研究センター 准教授
• 2004年04月 - 2010年09月 名古屋大学大学院工学研究科化学・生物工学専攻 助教
• 2000年 - 2004年 新潟大学 大学院自然科学研究科
• 2004年 - Department of Applied Chemistry, Graduate School of Engineering, Nagoya University

学歴

•         - 2000年   名古屋大学大学院工学研究科   応用化学専攻
•         - 2000年   名古屋大学
•         - 1994年   名古屋大学   工学部   応用化学科
•         - 1994年   名古屋大学

所属学協会

• 日本化学会   石油学会   触媒学会   

研究活動情報

論文

• In situ/operando spectroscopic evidence on associative redox mechanism for periodic unsteady-state water–gas shift reaction on Au/CeO2 catalyst

  Ningqiang Zhang, Lingcong Li, Yuan Jing, Yucheng Qian, Duotian Chen, Nobutaka Maeda, Toru Murayama, Takashi Toyao, Ken-ichi Shimizu

  Journal of Catalysis 2024年05月
• Microporosity and Catalytic Activity for Hydrodesulfurization of Pharmacosiderite Mo4P3O16 Synthesized at a Moderate Temperature

  Satoshi Ishikawa, Yudai Kosugi, Yasuharu Kanda, Kosuke Shimoda, Yuan Jing, Takashi Toyao, Ken-ichi Shimizu, Wataru Ueda

  Inorganic Chemistry 2024年04月29日
• The Development of the Regenerable Catalytic System in Selective Catalytic Oxidation of Ammonia with High N2 Selectivity

  Haifeng Wang, Toru Murayama, Tamao Ishida, Ken-ichi Shimizu, Norihito Sakaguchi, Kazuya Yamaguchi, Hiroki Miura, Tetsuya Shishido

  ACS Applied Materials & Interfaces 2024年04月17日
• Feeble Single-Atom Pd Catalysts for H2 Production from Formic Acid

  Esmail Doustkhah, Nao Tsunoji, Shinya Mine, Takashi Toyao, Ken-ichi Shimizu, Tetsuro Morooka, Takuya Masuda, M. Hussein N. Assadi, Yusuke Ide

  ACS Applied Materials & Interfaces 2024年02月28日
• Proton Conduction over the Zeolite with Surface Water Cluster for the Water Electrolysis at Neutral Condition

  Keigo Tashiro, Taisei Saito, Kojiro Goto, Junki Masuda, Takumi Miyakage, Shuhei Shimoda, Takashi Toyao, Nao Tsunoji, Ken‐ichi Shimizu, Hiroshige Matsumoto, Shigeo Satokawa

  ChemCatChem 2024年02月22日
• In Situ Spectroscopic Study of CO2 Capture and Methanation over Ni−Ca Based Dual Functional Materials

  Shinta Miyazaki, Duotian Chen, Bao Jiacheng, Takashi Toyao, Yasuharu Kanda, Ken‐ichi Shimizu

  Chemistry – An Asian Journal 2024年02月06日
• Low-Temperature CO2 Methanation over Ru Nanoparticles Supported on Monoclinic Zirconia

  Shohei Tada, Tomona Jinushizono, Kenya Ishikawa, Shinta Miyazaki, Takashi Toyao, Ken-ichi Shimizu, Masahiko Nishijima, Noriko Yamauchi, Yoshio Kobayashi, Ryuji Kikuchi

  Energy & Fuels 2024年02月01日
• Anaerobic Ammodehydrogenation of Ethane to Acetonitrile over Ga-Loaded H-FER Zeolite Catalysts

  Mengwen Huang, Xiaoming Hu, Duotian Chen, Zen Maeno, Nao Tsunoji, Takashi Toyao, Ken-ichi Shimizu

  ACS Catalysis 2024年01月19日
• Introduction to integrated approaches for methane activation

  Ken-ichi Shimizu, Wataru Ueda, Hua Song

  Catalysis Science & Technology 2024年
• Influence of temperatures and loadings on olefin diffusion in MFI-type zeolites in one- to three-dimensions

  Jiahuan Tong, Takumi Miyakage, Takashi Toyao, Ken-ichi Shimizu

  Catalysis Science & Technology 2024年
• Catalytic ammonia synthesis on HY-zeolite-supported angstrom-size molybdenum cluster

  Satoshi Kamiguchi, Kiyotaka Asakura, Tamaki Shibayama, Tomoko Yokaichiya, Tatsushi Ikeda, Akira Nakayama, Ken-ichi Shimizu, Zhaomin Hou

  Chemical Science 2024年 

  A molybdenum halide cluster complex is converted to an angstrom-size metal cluster on HY zeolite. The cluster efficiently catalyzes ammonia synthesis owing to high N₂ activation ability brought by cooperation of the multiple molybdenum sites.
• Continuous direct air capture and methanation using combined system of membrane-based CO2 capture and Ni-Ca based dual functional materials

  Lingcong Li, Shinta Miyazaki, Ziyang Wu, Takashi Toyao, Roman Selyanchyn, Zen Maeno, Shigenori Fujikawa, Ken ichi Shimizu

  Applied Catalysis B: Environmental 339 2023年12月15日 

  Direct CO2 capture from the air by membranes (membrane-based DAC, m-DAC) is a promising new technique to achieve CO2 net zero emissions. In addition, a continuous system for CO2 capture and its reduction by hydrogen using coupled reactors has scarcely been investigated. In this study, a new continuous system consisting of a m-DAC and a methanation process (m-DAC-M) was developed. For methanation, Ni nanoparticles supported on Ca-loaded Al2O3 (Ni-Ca/Al2O3; 10 wt% Ni and 6 wt% CaO) were utilized as a dual functional material (DFM). The Ni-Ca/Al2O3 exhibited high CH4 productivity and selectivity, good stability over 100 h, and high humidity resistance properties at a low reaction temperature of 350 °C. The catalytic properties of Ni-Ca/Al2O3 were elucidated using microscopic and spectroscopic techniques. The characterization results indicated that the CaO species not only served as CO2 adsorption sites to trap concentrated CO2 from the m-DAC system but also improved the reducibility of oxidized Ni species in the hydrogenation period, thereby promoting the reduction of surface carbonate species to CH4.
• Continuous Unsteady-State De-NOx System via Tandem Water–Gas Shift, NH3 Synthesis, and NH3–SCR under Periodic Lean/Rich Conditions

  Ningqiang Zhang, Yucheng Qian, Takashi Toyao, Ken-ichi Shimizu

  Environmental Science & Technology 2023年12月05日
• Rb-Ni/Al2O3 as dual functional material for continuous CO2 capture and selective hydrogenation to CO

  Lingcong Li, Ningqiang Zhang, Ziyang Wu, Shinta Miyazaki, Takashi Toyao, Zen Maeno, Ken-ichi Shimizu

  Chemical Engineering Journal 2023年12月
• Mechanism of NH3-SCR over P/CeO2 Catalysts Investigated by Operando Spectroscopies

  Ningqiang Zhang, Jiahuan Tong, Shinta Miyazaki, Shirun Zhao, Hiroe Kubota, Yuan Jing, Shinya Mine, Takashi Toyao, Ken-ichi Shimizu

  Environmental Science & Technology 2023年10月31日
• Promotional Effect of Ag on the Catalytic Decomposition of N2O in the Presence of O2 over the Al2O3-Supported Rh Catalyst

  Yuan Jing, Chenxi He, Ningqiang Zhang, Yu Murano, Ryo Toyoshima, Hiroshi Kondoh, Yuuta Kageyama, Hironori Inomata, Takashi Toyao, Ken-ichi Shimizu

  ACS Catalysis 2023年10月06日
• Continuous production of O2-free enriched CO2 from ambient air using moisture swing sorbents

  Shinta Miyazaki, Masaki Yoshihara, Takashi Toyao, Zen Maeno, Ken-ichi Shimizu

  Next Nanotechnology 2023年09月
• Bifunctionality of Re Supported on TiO2 in Driving Methanol Formation in Low-Temperature CO2 Hydrogenation

  Nat Phongprueksathat, Kah Wei Ting, Shinya Mine, Yuan Jing, Ryo Toyoshima, Hiroshi Kondoh, Ken-ichi Shimizu, Takashi Toyao, Atsushi Urakawa

  ACS Catalysis 2023年08月18日
• Prediction of Stable Surfaces of Metal Oxides through the Unsaturated Coordination Index

  Shunsaku Yasumura, Takashi Kamachi, Takashi Toyao, Ken-ichi Shimizu, Yoyo Hinuma

  ACS Omega 2023年08月15日
• Dynamic Behavior of Intermediate Adsorbates to Control Activity and Product Selectivity in Heterogeneous Catalysis: Methanol Decomposition on Pt/TiO2(110)

  Can Liu, Bang Lu, Hiroko Ariga-Miwa, Shohei Ogura, Takahiro Ozawa, Katsuyuki Fukutani, Min Gao, Jun-ya Hasegawa, Ken-ichi Shimizu, Kiyotaka Asakura, Satoru Takakusagi

  JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 145 36 19953 - 19960 2023年08月 

  Dynamic behavior of intermediate adsorbates, such as diffusion, spillover, and reverse spillover, has a strong influence on the catalytic performance in oxide-supported metal catalysts. However, it is challenging to elucidate how the intermediate adsorbates move on the catalyst surface and find active sites to give the corresponding products. In this study, the effect of the dynamic behavior of methoxy intermediate on methanol decomposition on a Pt/TiO2(110) surface has been clarified by combination of scanning tunneling microscopy (STM), temperature-programmed desorption (TPD), and density functional theory (DFT) calculations. The methoxy intermediates were formed by the dissociative adsorption of methanol molecules on Pt nanoparticles at room temperature followed by spillover to the TiO2(110) support surface. TPD results showed that the methoxy intermediates were thermally decomposed at >350 K on the Pt sites to produce CO (dehydrogenation) and CH4 (C-O bond scission). A decrease of the Pt nanoparticle density lowered the activity for the decomposition reaction and increased the selectivity toward CH4, which indicates that the reaction is controlled by diffusion and reverse spillover of the methoxy intermediates. Time-lapse STM imaging and DFT calculations revealed that the methoxy intermediates migrate on the five-fold coordinated Ti (Ti-5c) sites along the [001] or [1 (1) over bar 0] direction with the aid of hydrogen adatoms bonded to the bridging oxygens (O-br) and can move over the entire surface to seek and find active Pt sites. This work offers an in-depth understanding of the important role of intermediate adsorbate migration in the control of the catalytic performance in oxide-supported metal catalysts.
• Molybdenum Oxide Constructed by {Mo6O21}6– Pentagonal Unit Assembly and Its Redox Properties

  Kosuke Shimoda, Satoshi Ishikawa, Mai Miyasawa, Ken-ichi Shimizu, Wataru Ueda

  Inorganic Chemistry 2023年07月24日
• Mechanism of the Periodic Unsteady-State Water–Gas Shift Reaction on Highly Dispersed Cu-Loaded CeO2 Catalysts

  Ningqiang Zhang, Shinta Miyazaki, Yucheng Qian, Yuan Jing, Takashi Toyao, Ken-ichi Shimizu

  ACS Catalysis 2023年07月07日
• Operando Spectroscopic Study of Reduction and Oxidation Half-Cycles in NH3–SCR over CeO2-Supported WO3

  Hiroe Kubota, Yuan Jing, Li Wan, Jiahuan Tong, Ningqiang Zhang, Shinya Mine, Takashi Toyao, Ryo Toyoshima, Hiroshi Kondoh, Davide Ferri, Ken-ichi Shimizu

  ACS Catalysis 2023年07月07日 [査読有り]
  
• Sodium ion intercalation in vanadium oxide promotes low-temperature NH3-SCR activity: Sodium vanadium bronzes (Na0.33V2O5) for NOx removal

  Yusuke Inomata, Hiroe Kubota, Yoshinori Honmatsu, Hiroaki Takamitsu, Sosuke Sakotami, Kazuhiro Yoshida, Takashi Toyao, Ken-ichi Shimizu, Toru Murayama

  APPLIED CATALYSIS B-ENVIRONMENTAL 328 2023年07月 

  NH3-SCR (selective catalytic reduction) is a key technique for converting harmful NOx to harmless N2 and H2O in exhaust gases. Herein, V2O5, Na0.33V2O5 and Na1.2V3O8 are synthesized by a simple chemical process (the oxalate method) as examples of Na-intercalated vanadium oxide (sodium vanadium oxide bronze) for low-temperature NH3-SCR less than 150 degrees C. Among them, Na0.33V2O5 shows 92% (dry) and 86% (in the presence of 10 vol% water) NO conversions at 150 degrees C. The reaction rate of Na0.33V2O5 is 6.1-times higher than that of V2O5, indi-cating that Na intercalation accelerates NH3-SCR cycles. Mechanistic analysis suggests that the reaction mech-anism of Na0.33V2O5 is different from those of other V-based catalysts. Although it has been believed that alkali ions inhibit catalytic cycles of NH3-SCR, the results of this study suggest that alkali ions affect the structural, redox and adsorption properties of bulk V2O5, leading to an increase in NH3-SCR activity.
• Chemical Looping Dry Reforming of Methane over Ni-Modified WO3/ZrO2: Cooperative Work of Dispersed Tungstate Species and Ni over the ZrO2 Surface

  Shinta Miyazaki, Zirui Li, Lingcong Li, Takashi Toyao, Yuta Nakasaka, Yasushi Nakajima, Ken-ichi Shimizu, Zen Maeno

  Energy & Fuels 2023年06月01日
• Acid Catalysis over Crystalline Zr₃SO₉: Role of the Local Structure in Generating Acidity

  Meilin Tao, Satoshi Ishikawa, Takuji Ikeda, Shunsaku Yasumura, Kosuke Shimoda, Ryota Osuga, Yuan Jing, Takashi Toyao, Ken-ichi Shimizu, Hiromi Matsuhashi, Wataru Ueda

  ACS Catalysis 4517 - 4532 2023年03月20日
• Development of a Highly Stable Ternary Alloy Catalyst for Dry Reforming of Methane

  Ke Liu, Feilong Xing, Yiying Xiao, Ning Yan, Ken-ichi Shimizu, Shinya Furukawa

  ACS CATALYSIS 13 6 3541 - 3548 2023年03月 

  Dry reforming of methane is a promising chemical reaction that can utilize CO2 and natural gas to produce value-added feedstocks. However, this process's commercialized implementation has been stalled due to the lack of excellent durable and reusable catalysts. Here, we report a pseudo-binary alloy (Ni0.5Co0.5)3Ge/SiO2, which partially substitutes Ni with Co without altering the parent Ni3Ge phase. The combination of high-angle annular dark-field- scanning transmission electron microscopy-energy-dispersive system, X-ray diffraction, and X-ray absorption fine-structure analysis showed the formation of a pseudo-binary alloy structure. High catalytic activity with remarkable thermal stability is produced by alloying Ni with Co and Ge during continuous operation of 1000 h (mean catalyst life: tau = 1300 h) at 700 degrees C even below the equilibrium conversion. Detailed characterization and theoretical calculations revealed that doping Co to Ni3Ge optimally modified the C-H activation ability, which minimized coke formation for high stability.
• Surface Engineering of Titania Boosts Electroassisted Propane Dehydrogenation at Low Temperature

  Jianshuo Zhang, Yuki Nakaya, Ken-ichi Shimizu, Shinya Furukawa

  ANGEWANDTE CHEMIE-INTERNATIONAL EDITION 2023年03月 

  Electric field catalysis using surface proton conduction, in which proton hopping and collision on the reactant are promoted by external electricity, is a promising approach to break the thermodynamic equilibrium limitation in endothermic propane dehydrogenation (PDH). This study proposes a catalyst design concept for more efficient electroassisted PDH at low temperature. Sm was doped into the anatase TiO2 surface to increase surface proton density by charge compensation. Pt-In alloy was deposited on the Sm-doped TiO2 for more favorable proton collision and selective propylene formation. The catalytic activity in electroassisted PDH drastically increased by doping an appropriate amount of Sm (1 mol % to Ti) where the highest propylene yield of 19.3 % was obtained at 300 degrees C where the thermodynamic equilibrium yield was only 0.5 %. Results show that surface proton enrichment boosts alkane dehydrogenation at low temperature.
• Active site tuning based on pseudo-binary alloys for low-temperature acetylene semihydrogenation

  Jiamin Ma, Feilong Xing, Ken-ichi Shimizu, Shinya Furukawa

  Chemical Science 2023年02月24日
• Continuous CO2 capture and methanation over Ni–Ca/Al2O3 dual functional materials

  Lingcong Li, Ziyang Wu, Shinta Miyazaki, Takashi Toyao, Zen Maeno, Ken-ichi Shimizu

  RSC Advances 2023年
• In situ Ga K-edge XANES study of Ga-exchanged zeolites at high temperatures under different atmospheres including vacuum, CO, and pressurized H2

  Mengwen Huang, Tetsuya Kinjo, Shunsaku Yasumura, Takashi Toyao, Daiju Matsumura, Hiroyuki Saitoh, Ken-ichi Shimizu, Norikazu Namiki, Zen Maeno

  Catalysis Science & Technology 2023年
• In- and Ga-oxo clusters/hydrides in zeolites: speciation and catalysis for light-alkane activations/transformations

  Huang Mengwen, Shinsaku Yasumura, Takashi Toyao, Ken-ichi Shimizu, Zen Maeno

  Physical Chemistry Chemical Physics 2023年
• Multi-functionality of rhodium-loaded MOR zeolite: production of H2via the water gas shift reaction and its use in the formation of NH3

  Shunsaku Yasumura, Ken Nagai, Yucheng Qian, Takashi Toyao, Zen Maeno, Ken-ichi Shimizu

  Catalysis Science & Technology 2023年
• An automated reaction route mapping for the reaction of NO and active species on Ag4 clusters in zeolites

  Shunsaku Yasumura, Taisetsu Kato, Takashi Toyao, Zen Maeno, Ken-ichi Shimizu

  Physical Chemistry Chemical Physics 2023年
• Stability and Metastability of Li3YCl6 and Li3HoCl6

  Hiroaki Ito, Yuki Nakahira, Naoki Ishimatsu, Yosuke Goto, Aichi Yamashita, Yoshikazu Mizuguchi, Chikako Moriyoshi, Takashi Toyao, Ken Ichi Shimizu, Hiroshi Oike, Masanori Enoki, Nataly Carolina Rosero-Navarro, Akira Miura, Kiyoharu Tadanaga

  Bulletin of the Chemical Society of Japan 69 11 1262 - 1268 2023年 

  Metastable solid electrolytes exhibit superior conductivity compared to stable ones, making them a subject of considerable interest. However, synthesis of the metastable phase is affected by multiple thermodynamic and kinetic parameters, leading to ambiguity in the organization of stability and metastability. Thus, remnant and intermediate metastability was organized based on temperature. The intermediate metastable phase, which is less stable than the temperature-independent stable phase, typically transforms into the stable phase(s) at high temperatures. Meanwhile, the remnant metastable phase is formed by first obtaining most stable phase at specific temperatures and then “trapping” it by rapidly changing the temperature. By investigating Li+ conducting chlorides, Li3MCl6 (M = Y and Ho), heating starting materials to approximately 600 K produced low-temperature Li3MCl6 phase with one formula unit while further heating resulted in high-temperature Li3MCl6 phase with three formula units. Annealing quenched Li3MCl6 at 573 K resulted in a phase transition from the high-temperature to low-temperature phase, indicating that the high-temperature phase was remnant metastable at low temperatures.
• Propane metathesis and hydrogenolysis over titanium hydride catalysts

  Mengwen Huang, Yosuke Tomimuro, Shinta Miyazaki, Shinya Mine, Takashi Toyao, Yoyo Hinuma, Yasuharu Kanda, Masaaki Kitano, Ken-ichi Shimizu, Zen Maeno

  Catalysis Science & Technology 13 21 6247 - 6253 2023年 

  Propane metathesis reactions over group 2–5 metal hydrides were investigated where TiH₂ exhibited the highest butane formation amount. This study is the first example of carbon–carbon bond cleavage and formation over bulk metal hydrides.
• Regeneration of atomic Ag sites over commercial γ-aluminas by oxidative dispersion of Ag metal particles

  Hiroe Kubota, Shinya Mine, Takashi Toyao, Ken-ichi Shimizu

  Catalysis Science & Technology 2023年 [査読有り]
  
• Interstitial Carbon Dopant in Palladium-Gold Alloy Boosting the Catalytic Performance in Vinyl Acetate Monomer Synthesis

  Yuki Nakaya, Eigo Hayashida, Ruikun Shi, Ken-ichi Shimizu, Shinya Furukawa

  JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 2023年01月 

  Vinyl acetate monomer (VAM), an important chemical intermediate in industry, is produced by the well-established commercial process of acetoxylation of ethylene with Pd-Au/SiO2 and a KOAc promoter. No paper has since decades defined the true effects of Au and KOAc, despite numerous attempts to clarify them. The role of subsurface carbon as a catalyst booster for enhanced catalytic performance in VAM synthesis was found by us for the first time. X-ray diffraction and X-ray absorption fine structure studies revealed that carbon atoms spontaneously doped into the Pd-Au alloy lattice while maintaining the alloy's size, metallic state, and alloy composition. Additionally, during the process, the KOAc addition dramatically raised the equilibrium carbide fraction. Because of the high carbide fraction, KOAc/Pd0.8Au0.2/SiO2 had a 5.6-fold higher formation rate (89.0% selectivity) than Pd0.8Au0.2/SiO2 (69.2% selectivity) due to high carbide fraction. Surprisingly, kinetic and theoretical analyses showed that the coupling of acetate and ethylene, which is a rate-determining step, is effectively promoted by the synergistic contributions of Au (electronic/geometric effects) and interstitial carbon (electronic effect). Additionally, the synergy inhibits ethylene dehydrogenation, which ultimately slows the formation of CO2. The contentious debates about the roles of Au and KOAc in the acetoxylation of ethylene have been resolved thanks to experimental and theoretical insights into the roles of Pd-Au formation, Au/Pd ratio, and interstitial carbon atoms. These insights also open the door for the logical design of catalysts with desirable catalytic performance.
• Promoting effect of basic metal additives on DeNOx reactions over Pt-based three-way catalysts

  Yuan Jing, Gang Wang, Shinya Mine, Jumpei Kawai, Ryo Toyoshima, Hiroshi Kondoh, Xiaorui Zhang, Shuhei Nagaoka, Ken-ichi Shimizu, Takashi Toyao

  Journal of Catalysis 416 209 - 221 2022年12月 [査読有り]
  
• Dynamic Structural Evolution of [Rh(NO)2]+ Complex/Rh Metal Cluster in Zeolite during de-NOx via in Situ Formed NH3 under Lean/Rich Periodic Conditions

  Shunsaku Yasumura, Taisetsu Kato, Yucheng Qian, Takashi Toyao, Zen Maeno, Ken-ichi Shimizu

  The Journal of Physical Chemistry C 2022年11月17日
• Lewis Acid Promoted Sustainable Transformation of Triglycerides to Fatty Acids Using a Water-Tolerant Nb2O5 Catalyst

  Abeda Sultana Touchy, Md. Nurnobi Rashed, Mengwen Huang, Takashi Toyao, Ken-ichi Shimizu, S. M. A. Hakim Siddiki

  ACS Sustainable Chemistry & Engineering 2022年09月12日
• High-Entropy Intermetallics Serve Ultrastable Single-Atom Pt for Propane Dehydrogenation

  Yuki Nakaya, Eigo Hayashida, Hiroyuki Asakura, Satoru Takakusagi, Shunsaku Yasumura, Ken-ichi Shimizu, Shinya Furukawa

  Journal of the American Chemical Society 144 35 15944 - 15953 2022年09月07日
• High-entropy intermetallics on ceria as efficient catalysts for the oxidative dehydrogenation of propane using CO2

  Feilong Xing, Jiamin Ma, Ken-ichi Shimizu, Shinya Furukawa

  Nature Communications 13 1 2022年08月29日 

  Abstract The oxidative dehydrogenation of propane using CO₂ (CO₂-ODP) is a promising technique for high-yield propylene production and CO₂ utilization. The development of a highly efficient catalyst for CO₂-ODP is of great interest and benefit to the chemical industry as well as net zero emissions. Here, we report a unique catalyst material and design concept based on high-entropy intermetallics for this challenging chemistry. A senary (PtCoNi)(SnInGa) catalyst supported on CeO₂ with a PtSn intermetallic structure exhibits a considerably higher catalytic activity, C₃H₆ selectivity, long-term stability, and CO₂ utilization efficiency at 600 °C than previously reported. Multi-metallization of the Pt and Sn sites by Co/Ni and In/Ga, respectively, greatly enhances propylene selectivity, CO₂ activation ability, thermal stability, and regenerable ability. The results obtained in this study can promote carbon-neutralization of industrial processes for light alkane conversion.
• Accelerated discovery of multi-elemental reverse water-gas shift catalysts using extrapolative machine learning approach

  Gang Wang, Shinya Mine, Duotian Chen, Yuan Jing, Kah Wei Ting, Taichi Yamaguchi, Motoshi Takao, Zen Maeno, Ichigaku Takigawa, Koichi Matsushita, Ken-ichi Shimizu, Takashi Toyao

  2022年08月25日 

  Designing novel catalysts is key to solving many energy and environmental challenges. Despite the promise that data science approaches, including machine learning (ML), can accelerate the development of catalysts, truly novel catalysts have rarely been discovered by ML because of one of its most common limitations and criticisms—the assumed inability of the models to extrapolate and identify extraordinary materials beyond those present in the training data set. Herein, we demonstrate an extrapolative ML approach to develop new multi-elemental catalysts based on supported Pt as an active metal and TiO2 as a support for the low-temperature reverse water-gas shift (RWGS) reaction. Using 45 catalysts as the initial data points and performing 44 cycles of the closed loop discovery system (ML prediction + experiment), we experimentally tested a total of 300 catalysts and identified more than 100 catalysts with superior activity as compared to the previously reported high-performance catalysts. The composition of the optimal catalyst discovered by this approach was Pt(3)/Rb(1)-Ba(1)-Mo(0.6)-Nb(0.2)/TiO2. Notably, Nb was not included in the original dataset, and the catalyst composition identified was unpredictable even by human experts.
• Computational Design of Main-Group Catalysts for Low-Temperature Methane Combustion by Ozone

  Shunsaku Yasumura, Kenichiro Saita, Takumi Miyakage, Kenichi Kon, Takashi Toyao, Zen Maeno, Tetsuya Taketsugu, Ken-ichi Shimizu

  Nature Communications 2022年08月23日 

  The catalytic combustion of methane (CH4) at a low temperature is becoming increasingly key to controlling unburned CH4 emissions from natural gas vehicles and power plants, although the low activity of benchmark platinum-group-metal (PGM) catalysts hinders its application. Based on the automated reaction route mapping, we designed the main-group catalyst for low-temperature CH4 combustion with ozone (O3). The computational screening of the active site predicted the strong Brønsted acid sites (BASs) as promising ones. We experimentally demonstrated that the catalyst comprising strong BASs exhibited improved CH4 conversion at 200 °C, correlating with the theoretically predicted design concept. The main-group catalyst (proton-type beta zeolite) delivered a reaction rate, which was 442 times higher than that of a benchmark catalyst (5wt% Pd-loaded Al2O3), at 190 °C and exhibited higher tolerance to steam and SO2. Our strategy demonstrated the rational design of earth-abundant catalysts based on automated reaction route mapping.
• In Situ/Operando Spectroscopic Studies on the NH3–SCR Mechanism over Fe–Zeolites

  Shunsaku Yasumura, Yucheng Qian, Taisetsu Kato, Shinya Mine, Takashi Toyao, Zen Maeno, Ken-ichi Shimizu

  ACS Catalysis 2022年08月19日 [査読有り]
  
• Designing Adsorptive Gating via Linker Side-Chain Functionalization in a Honeycomb-MOF

  Jan Berger, Andreas Schneemann, Inke Hante, Yuan Jing, Jack D. Evans, Yuh Hijikata, Jenny Pirillo, Takashi Toyao, Ken-ichi Shimizu, Shin-ichiro Noro, Gregor Kieslich, Roland A. Fischer

  The Journal of Physical Chemistry C 2022年08月04日 [査読有り]
  
• Layered silicate stabilises diiron to mimic UV-shielding TiO2 nanoparticle

  Hamza El-Hosainy, Shinya Mine, Takashi Toyao, Ken-ichi Shimizu, Nao Tsunoji, Mohamed Esmat, Esmail Doustkhah, Maged El-Kemary, Yusuke Ide

  MATERIALS TODAY NANO 19 2022年08月 

  Despite the ubiquity of aqua-Fe(III) complexes in biological enzymes and their useful properties and cost-effectiveness, artificially stabilizing these fleeting molecules for practical uses remains challenging. Herein, we demonstrate that a dimeric aqua-Fe(III) species can be stabilised using a flexible microporous layered silicate to produce a white UV-absorbing powder with significantly reduced undesirable photocatalytic activity. A mixture of this powder material and a natural oil is successfully employed to shield a UV-sensitive substrate; its shielding performance was comparable to that of a commercial-TiO(2)( )rutile coating. Comprehensive analyses and calculations reveal that a dihydroxo-bridged dimer, [(H2O)(OH)(2)O5FeIII(OH)(2)(FeOS)-O-III(H2O) (OH)(2)] (O-S: framework oxygen), fits the silicate pore and account for the stabilities and shielding properties of the material. Although TiO2 nanoparticles are widely used as UV absorbers in sunscreens and cosmetics, they pose health risks owing to their cytotoxicity. Thus, this material can serve as a safe, cost-effective alternative to TiO2 nanoparticles, either as a UV absorber or in other applications. (C) 2022 Elsevier Ltd. All rights reserved.
• Mechanism of Standard NH3–SCR over Cu-CHA via NO+ and HONO Intermediates

  Chong Liu, Shunsaku Yasumura, Takashi Toyao, Zen Maeno, Ken-ichi Shimizu

  The Journal of Physical Chemistry C 2022年07月21日
• In Situ Spectroscopic Studies of the Redox Catalytic Cycle in NH3–SCR over Chromium-Exchanged Zeolites

  Shunsaku Yasumura, Yucheng Qian, Takashi Toyao, Zen Maeno, Ken-ichi Shimizu

  The Journal of Physical Chemistry C 2022年07月14日
• Hollow-Form LaNiO3 Perovskite Catalyst for PM Combustion Using Carbon Fibers as a Template

  Kazumasa Oshima, Masataka Sakamoto, Kazumasa Morita, Kenichi Kon, Ken-ichi Shimizu, Tsuyoshi Yamamoto, Masahiro Kishida, Shigeo Satokawa

  JOURNAL OF CHEMICAL ENGINEERING OF JAPAN 55 7 2022年07月
• Experimental studies on intracrystalline diffusion of NO and NH3 in Cu-CHA

  Yuta Nakasaka, Keigo Kushima, Shunsaku Yasumura, Ken-ichi Shimizu, Keigo Totani, Gen Shibata, Takao Masuda

  Catalysis Today 2022年07月
• Application to Electroluminescence Devices with Dimethylformamide-Stabilized Niobium Oxide Nanoparticles

  Honami Iguchi, Mitsuru Inada, Shunsuke Aratani, Moegi Nomura, Takeyuki Suzuki, Yuan Jing, Takashi Toyao, Zen Maeno, Ken-ichi Shimizu, Yasushi Obora

  ACS Applied Nano Materials 5 6 7658 - 7663 2022年06月24日
• Trends in Surface Oxygen Formation Energy in Perovskite Oxides

  Yoyo Hinuma, Shinya Mine, Takashi Toyao, Ken-ichi Shimizu

  ACS Omega 7 22 18427 - 18433 2022年06月07日 [査読有り]
  
• Catalytic Decomposition of N2O in the Presence of O2 through Redox of Rh Oxide in a RhOx/ZrO2 Catalyst

  Yuan Jing, Koichiro Taketoshi, Ningqiang Zhang, Chenxi He, Takashi Toyao, Zen Maeno, Teppei Ohori, Naoya Ishikawa, Ken-ichi Shimizu

  ACS Catalysis 6325 - 6333 2022年06月03日
• Steady-state kinetic modeling of NH3-SCR by monolithic Cu-CHA catalysts

  Gen Shibata, Naoki Shibayama, Keita Araki, Yoshimitsu Kobashi, Hideyuki Ogawa, Yuta Nakasaka, Ken-ichi Shimizu

  Catalysis Today 2022年06月
• Super Mg²⁺ Conductivity around 10^–3 S cm^–1 Observed in a Porous Metal–Organic Framework

  Yuto Yoshida, Teppei Yamada, Yuan Jing, Takashi Toyao, Ken-ichi Shimizu, Masaaki Sadakiyo

  Journal of the American Chemical Society 144 19 8669 - 8675 2022年05月18日
• Defective NiO as a Stabilizer for Au Single-Atom Catalysts

  Chihiro Mochizuki, Yusuke Inomata, Shunsaku Yasumura, Mingyue Lin, Ayako Taketoshi, Tetsuo Honma, Norihito Sakaguchi, Masatake Haruta, Ken-ichi Shimizu, Tamao Ishida, Toru Murayama

  ACS Catalysis 6149 - 6158 2022年05月09日
• Oxidation Catalysis over Solid-State Keggin-Type Phosphomolybdic Acid with Oxygen Defects.

  Satoshi Ishikawa, Takuji Ikeda, Maki Koutani, Shunsaku Yasumura, Kazuhiko Amakawa, Kosuke Shimoda, Yuan Jing, Takashi Toyao, Masahiro Sadakane, Ken-Ichi Shimizu, Wataru Ueda

  Journal of the American Chemical Society 144 17 7693 - 7708 2022年05月04日 

  Keggin-type phosphomolybdic acid (PMo12O40), treated with pyridine (Py), forms a crystalline material (PyPMo-HT) following heat treatment under an inert gas flow at ∼420 °C. Although this material is known to have attractive catalytic properties for gas-phase oxidation, the origin of this catalytic activity requires clarification. In this study, we investigated the crystal structure of PyPMo-HT. PyPMo-HT comprises a one-dimensional array of Keggin units and pyridinium cations (HPy), with an HPy/Keggin unit ratio of ∼1.0. Two oxygen atoms were removed from the Keggin unit during crystal structure transformation, which resulted in an electron being localized on the Mo atom in close contact with the adjacent Keggin unit. Upon the introduction of molecular oxygen, electron transfer from this Mo atom resulted in the formation of an electrophilic oxygen species that bridged two Keggin units. The electrophilic oxygen species acted as a catalytically active oxygen species, as confirmed by the selective oxidation of propylene. PyPMo-HT showed excellent catalytic activity for the selective oxidation of methacrolein, with the methacrylic acid yield being superior to that obtained with PMo12O40 and comparable to that obtained with an industrial Keggin-type polyoxometalate (POM) catalyst. The oxidation catalysis observed over PyPMo-HT provides a deeper understanding of POM-based industrial catalytic processes.
• Nickel-Based High-Entropy Intermetallic as a Highly Active and Selective Catalyst for Acetylene Semihydrogenation.

  Jiamin Ma, Feilong Xing, Yuki Nakaya, Ken-Ichi Shimizu, Shinya Furukawa

  Angewandte Chemie (International ed. in English) e202200889  2022年04月26日 

  Acetylene semihydrogenation is a key technology for producing polymer-grade ethylene from crude ethylene. Ni-based catalysts are promising alternatives to noble-metals for this process. However, achieving high catalytic activity and selectivity remains a big challenge. We report a novel catalyst design based on high-entropy intermetallics (HEI), which provide thermally stable isolated Ni without excess counterpart metals and achieve exceptionally high performance. Intermetallic NiGa was multi-metalized to a (NiFeCu)(GaGe), where the Ni and Ga sites were partially substituted with Fe/Cu and Ge, respectively, without altering the parent CsCl-type structure. The NiFeCuGaGe/SiO2 HEI catalyst completely inhibited ethylene overhydrogenation even at complete acetylene conversion, and exhibited five-times higher activity than other 3d-transition-metal-based catalysts. The DFT study showed that the surface energy decreased by multi-metallization, which drastically weakened ethylene adsorption.
• Enhancement of the hydrodesulfurization and C−S bond cleavage activities of rhodium phosphide catalysts by platinum addition

  Yasuharu Kanda, Ryo Saito, Taiki Ono, Kenichi Kon, Takashi Toyao, Shinya Furukawa, Yasushi Obora, Ken ichi Shimizu

  Journal of Catalysis 408 294 - 302 2022年04月 

  To enhance the hydrodesulfurization (HDS) activity of SiO2-supported Rh phosphide catalysts, various second metal-added Rh–P catalysts were developed; furthermore, the effect of the addition of the second metal on the HDS performance was examined. The second metals (M: Ru, Pt, and Ir) were selected as per the Sabatier principle. In situ X-ray diffraction revealed the formation of an Rh2P phase in the Rh–M–P catalyst after reduction. The addition of Ru and Pt to the Rh–P catalyst enhanced the C−S bond cleavage activity, whereas the addition of Ir had virtually no effect. The Rh–Pt–P catalyst demonstrated the highest HDS activity among Rh–M–P catalysts. The characterization results revealed the presence of positively charged Pt on the Rh–Pt–P catalyst surface, in which Pt and Rh cooperatively act as active sites to enhance the C−S bond cleavage activity.
• Role of Ba in an Al2O3-Supported Pd-based Catalyst under Practical Three-Way Catalysis Conditions

  Yuan Jing, Gang Wang, Shinya Mine, Zen Maeno, S. M.A. Hakim Siddiki, Masayuki Kobayashi, Shuhei Nagaoka, Ken ichi Shimizu, Takashi Toyao

  ChemCatChem 14 8 2022年04月 

  Barium (Ba) has been widely and successfully added to three-way catalysts to effectively control gasoline vehicle emissions. While the introduction of Ba is well-known to have a very significant impact on three-way catalysis (TWC) performance, the role of Ba under practical TWC conditions remains insufficiently understood. In this study, we investigated the role of Ba in a Pd-based catalyst in a standard TWC process using a gasoline vehicle and in situ/operando infrared (IR) spectroscopy. The addition of Ba was found to reduce all of the emissions considered (NOx, CO, and non-methane hydrocarbons) in the vehicle exhaust gas; it also suppressed supported-metal aggregation, which is a requirement of a high-performance catalyst. In addition, IR studies using model powder catalysts revealed that the efficient formation of intermediate surface nitrate species and their subsequent reactions with reductant gases, such as CO, H2, and C3H6 (as a hydrocarbon), play key roles in reducing emissions. This process is akin to the NOx storage and reduction (NSR) mechanism commonly used to control diesel emissions.
• Experimental and Theoretical Investigation of Metal-Support Interactions in Metal-Oxide-Supported Rhenium Materials

  Shinya Mine, Kah Wei Ting, Lingcong Li, Yoyo Hinuma, Zen Maeno, S. M.A.Hakim Siddiki, Takashi Toyao, Ken Ichi Shimizu

  Journal of Physical Chemistry C 126 9 4472 - 4482 2022年03月10日 

  The activity and stability of supported metal catalysts is significantly influenced by the interactions between the metal and the support, the so-called metal-support interactions (MSIs). Here, we present a systematic study that uses both experimental and computational approaches to investigate MSIs between Re and oxide supports. Re dispersed on SiO2, Al2O3, and MgO tends to be aggregated whereas Re dispersed on TiO2, V2O5, ZrO2, Nb2O5, and CeO2exhibits a high degree of dispersion. Electronic properties such as the position of the conduction-band minimum (CBM) of the oxide support, a proxy for the electron affinity (EA), and the Fermi energy (EF) of the supported Re, a proxy for the work function (WF), were found to be of particular importance to govern the degrees of dispersion and aggregation of Re. Metal-oxide supports that have an EA that is larger than the WF of Re, such as TiO2, V2O5, and CeO2, can accept electrons from Re into their CB, inducing a strong MSI. This results in a large Re adsorption energy (Eads) that leads to a high degree of dispersion for the supported Re metal. Our work describing the electronic interactions that govern the degree of dispersion will enable the synthesis of active and durable catalysts via the identification of suitable combinations of metals and oxides.
• Machine Learning Analysis of Literature Data on the Water Gas Shift Reaction toward Extrapolative Prediction of Novel Catalysts

  Mine Shinya, Jing Yuan, Mukaiyama Takumi, Takao Motoshi, Maeno Zen, Shimizu Ken-ichi, Takigawa Ichigaku, Toyao Takashi

  Chemistry Letters 51 3 269 - 273 2022年03月05日 [査読無し]
  
• High-loading Ga-exchanged MFI zeolites as selective and coke-resistant catalysts for nonoxidative ethane dehydrogenation

  Mengwen Huang, Shunsaku Yasumura, Lingcong Li, Takashi Toyao, Zen Maeno, Ken Ichi Shimizu

  Catalysis Science and Technology 12 3 986 - 995 2022年02月07日 

  In this paper, we investigated the effects of the Ga loading amount and H2 treatment temperature for the reductive solid-state ion-exchange reaction on the generated Ga species in Ga-exchanged MFI zeolites (Ga-MFIs) as well as their catalysis for ethane dehydrogenation (EDH). For the formation of isolated Ga hydrides in the zeolites, [GaH]2+ ions were preferentially formed in the low-loading Ga-MFI (Ga/Al = 0.3) treated with H2 at 550 °C, corresponding to the conventional preparation conditions, (Ga-MFI-0.3(550)), while the high Ga loading (Ga/Al = 1.0) and high-temperature H2 treatment (800 °C) (Ga-MFI-1.0(800)) induced the formation of [GaH2]+ ions as the major Ga hydrides, as revealed by in situ Fourier transform infrared spectroscopy including the isotope experiment using D2. In the context of other Ga species, such as Ga+ cations and partially reduced Ga oxides (GaOX), Ga+ cations and GaOX coexist in Ga-MFI-0.3(550), as indicated by pyridine adsorption experiments. On the other hand, GaOX was hardly observed and a larger amount of Ga+ cations was formed in Ga-MFI-1.0(800). The remaining Brønsted acid sites (BASs) were also characterized by the NH3 adsorption experiment. In the EDH reaction, Ga-MFI-1.0(800) exhibited high selectivity owing to low coke formation, resulting in the highest durability among the series of Ga-MFIs tested. Under the optimized conditions, Ga-MFI-1.0(800) exhibited the highest C2H4 formation rate among previously reported Pt-free catalysts. Based on the combined results of characterization, catalyst tests, and kinetic studies, the high selectivity and durability of Ga-MFI-1.0(800) can be ascribed to the low amount of the remaining BASs by isolated Ga species ([GaH]2+, [GaH2]+ ions and Ga+ cations) as well as the major formation of [GaH2]+ ions among isolated Ga hydrides.
• Catalytic Methylation of Benzene over Pt/MoOx/TiO2 and Zeolite Catalyst Using CO2 and H2

  Kah Wei Ting, Takuto Imbe, Haruka Kamakura, Zen Maeno, S. M.A.Hakim Siddiki, Koichi Matsushita, Ken Ichi Shimizu, Takashi Toyao

  Chemistry Letters 51 2 149 - 152 2022年02月 

  Catalytic methylation of benzene using CO2/H2 was investigated using various combinations of supported metal catalysts and zeolites in a batch reactor. After a thorough catalyst screening process, the combination of Pt(3)/MoOx(30)/TiO2 and H-MOR (SiO2/Al2O3 = 90) was the most efficient, achieving up to 39% benzene-based yield and 27% CO2-based yield, without promoting the dearomatization of benzene, under the reaction conditions employed in this study (1 MPa CO2, 5 MPa H2, 1mmol of benzene, 240 °C, 12 h).
• N,N-Dimethylformamide-protected Fe2O3 Combined with Pt Nanoparticles: Characterization and Catalysis in Alkene Hydrosilylation

  Tatsuki Nagata, Tatsuya Tanaka, Xianjin Lin, Ryota Kondo, Takeyuki Suzuki, Yasuharu Kanda, Takashi Toyao, Ken ichi Shimizu, Yasushi Obora

  ChemCatChem 14 2 2022年01月21日 

  We report a combination of N,N-dimethylformamide (DMF)-protected Fe2O3 nanoparticles (NPs) and Pt NPs for the hydrosilylation of various industrially relevant alkenes and tertiary silanes. The DMF-protected Fe2O3 and Pt NPs catalysts were characterized by transmission electron microscopy, X-ray absorption spectroscopy, and X-ray photoelectron spectroscopy. The catalyst of DMF-protected Fe2O3 NPs combined with Pt NPs can be recycled for five cycles by a simple extraction using hexane/DMF. The developed combination Fe2O3/Pt NPs catalyst is effective up to the 1-kilogram scale.
• Redox-Driven Reversible Structural Evolution of Isolated Silver Atoms Anchored to Specific Sites on γ-Al2O3

  Hiroe Kubota, Shinya Mine, Takashi Toyao, Zen Maeno, Ken Ichi Shimizu

  ACS Catalysis 12 1 544 - 559 2022年01月07日 

  Reversible structural transformation between atomic Ag(I) and large Ag metal nanoparticles (NPs) on γ-Al2O3-supported Ag (Ag/Al2O3) catalysts for H2-assisted NOx selective catalytic reduction by NH3 was monitored by in situ X-ray absorption spectroscopy, ultraviolet–visible spectroscopy, infrared spectroscopy, and ex situ microscopy. Fresh Ag/Al2O3 was deactivated by H2 reduction at 800 °C owing to sintering of the atomic Ag(I) species to form large (10–52 nm) Ag metal NPs. Reoxidation of the sintered catalyst using NO + O2 at 400 °C resulted in the redispersion of Ag metal NPs to the atomic Ag(I) species, leading to the recovery of the catalytic activity. Sintering and dispersion occurred reversibly for 10 repetitive treatments of H2 ↔ NO + O2 at 600 °C. The structure of the anchoring site and the mechanism of oxidative dispersion were elucidated by kinetic studies, in situ spectroscopy, 27Al nuclear magnetic resonance spectroscopy, and density functional theory calculations. The isolated Ag(I) cation was exchanged with H+ of the HO-μ1-AlVI site adjacent to the strong Lewis acid sites (unsaturated AlIV3+) on γ-Al2O3, and, consequently, the anchored Ag(I) species reduced the Lewis acid strength of the adjacent AlIV3+ sites. During sintering under H2, the isolated AgO-μ1-AlVI species aggregated to form Ag metal NPs, regenerating the HO-μ1-AlVI sites on the support. During oxidative dispersion under the NO + O2 flow, the Ag metal NPs were oxidized to furnish mobile AgNO3 species that moved across the support surface and reacted with the anchoring site, HO-μ1-AlVI, to yield the original AgO-μ1-AlVI species and HNO3; the latter reacts with the γ-Al2O3 surface to yield the nitrate species. This study provides molecular level insights into the deactivation/reactivation of supported metal catalysts under reductive/oxidative conditions.
• Effect of oxygen storage materials on the performance of Pt-based three-way catalysts

  Gang Wang, Yuan Jing, Kah Wei Ting, Zen Maeno, Xiaorui Zhang, Shuhei Nagaoka, Ken-ichi Shimizu, Takashi Toyao

  Catalysis Science & Technology 2022年
• Dimethylacetamide-stabilized ruthenium nanoparticles for catalysing α-alkylations of amides with alcohols

  Honami Iguchi, Nobuki Katayama, Takeyuki Suzuki, Tetsuaki Fujihara, Yuan Jing, Takashi Toyao, Zen Maeno, Ken-ichi Shimizu, Yasushi Obora

  Chemical Communications 2022年
• The reducibility and oxidation states of oxide-supported rhenium: experimental and theoretical investigations

  Kah Wei Ting, Shinya Mine, Abdellah Ait El Fakir, Pengfei Du, Lingcong Li, S. M. A. Hakim Siddiki, Takashi Toyao, Ken-ichi Shimizu

  Physical Chemistry Chemical Physics 2022年
• N,N-Dimethylformamide-stabilized ruthenium nanoparticle catalyst for β-alkylated dimer alcohol formation via Guerbet reaction of primary alcohols

  Tatsuki Nagata, Kanji Okada, Ryota Kondo, Takashi Toyao, Ken-ichi Shimizu, Takeyuki Suzuki, Yasushi Obora

  RSC Advances 12 26 16599 - 16603 2022年 

  N,N-Dimethylformamide-stabilized Ru nanoparticles (NPs) provide a highly efficient catalyst for the Guerbet reaction of primary alcohols under solvent-free conditions and without the use of external ligands.
• Mechanistic study on three-way catalysis over Pd/La/Al2O3 with high La loading

  Yuan Jing, Gang Wang, Zen Maeno, Shuhei Nagaoka, Ken ichi Shimizu, Takashi Toyao

  Catalysis Today 2022年 

  Although La-loaded Al2O3 (La/Al2O3) is a widely used support material for three-way catalysis (TWC), little is known about the promotional effect of La in the La/Al2O3 supported Pd catalyst (Pd/La/Al2O3) in the catalytic NO reduction (DeNOx) for automotive emission control. Previously (Jing et al., 2020 [1]), we assessed the promotional effect of La and observed that the supported metallic Pd nanoparticles on the La/Al2O3 support were more electron-deficient than those on Al2O3 without La, which led to suppression of CO poisoning and a higher catalytic activity for NO reduction. Here, we further investigated the role of La in Pd/La/Al2O3 for the DeNOx process by various spectroscopic methods. The results obtained suggest that the efficient generation of nitrite species and its facile reactivity are important for the promotional effect of La in NO reduction. In addition, we investigated the effects of hydrothermal aging. For the TWC, Pd/La/Al2O3 with high La loading (15 wt%) was identified to be superior to the conventional industrial catalyst having a loading of 5 wt%. It was also found to show relatively high Pd dispersion even after aging at 800 °C. The observed stabilizing effect is an important benefit of the addition of La.
• Continuous CO2Capture and Selective Hydrogenation to CO over Na-Promoted Pt Nanoparticles on Al2O3

  Lingcong Li, Shinta Miyazaki, Shunsaku Yasumura, Kah Wei Ting, Takashi Toyao, Zen Maeno, Ken Ichi Shimizu

  ACS Catalysis 12 4 2639 - 2650 2022年 

  The capture of CO2 and its reduction with H2 to form C1 compounds (i.e., CO2 capture and reduction; CCR), such as CO and CH4, using dual-functional materials (DFMs) has recently attracted attention as a promising process for CO2 emission reduction and utilization. Although CO is more useful than CH4 from a chemical synthesis perspective, the development of an effective DFM system to generate CO has been explored much less than that for CH4 generation. This study successfully developed Na-promoted Pt nanoparticles (NPs) supported on Al2O3 (Pt-Na/Al2O3) as an effective DFM for selective CO production by capturing diluted CO2 from a mixture with O2 and successive reduction by H2. The developed Pt-Na/Al2O3 was applicable for continuous CCR operation using two reactors in parallel and switching feed gases. The CO2 capture ability and productivity of CO were maintained for at least 100 h. We also elucidated the effect of basic promoters through microscopic and spectroscopic characterizations. The Na-modified Pt nanoparticles (NPs) were formed on Al2O3, where Na species play two important roles in efficient CO2 capture and selective CO formation: (i) capturing CO2 from a mixture with O2 and (ii) inhibiting the adsorption of generated CO on Pt NPs.
• Ternary platinum-cobalt-indium nanoalloy on ceria as a highly efficient catalyst for the oxidative dehydrogenation of propane using CO2

  Feilong Xing, Yuki Nakaya, Shunsaku Yasumura, Ken-ichi Shimizu, Shinya Furukawa

  NATURE CATALYSIS 5 1 55 - 65 2022年01月 

  The oxidative dehydrogenation of propane using CO2 (CO2-ODP) is a promising technique for high-yield propylene production and CO2 utilization. Unfortunately the efficiency of existing catalysts is limited, and therefore, developing a highly efficient catalyst for CO2-ODP is of great importance for the chemical industry. Here we report a Pt-Co-In ternary nanoalloy on CeO2 that has a (Pt1-xCox)(2)In-3 pseudo-binary alloy structure and exhibits very high catalytic activity, C3H6 selectivity, stability and CO2 utilization efficiency at 550 degrees C. Alloying platinum with indium and cobalt significantly improves the C3H6 selectivity and CO2 reduction ability, respectively. The cobalt species provide a high density of states near the Fermi level, which lowers the energy barrier of CO2 reduction. The stability of the catalyst is greatly enhanced by combining the strong CO2 activation ability of the alloy with the oxygen releasing ability of the CeO2 support, which facilitates Mars-van Krevelen-type coke combustion.
• Propane Dehydrogenation Catalysis of Titanium Hydrides: Positive Effect of Hydrogen Co-feeding

  Shunsaku Yasumura, Yuxiang Wen, Takashi Toyao, Yasuharu Kanda, Ken-ichi Shimizu, Zen Maeno

  CHEMISTRY LETTERS 51 1 88 - 90 2022年01月 

  This study investigated non-oxidative propane dehydrogenation over TiH2. It was found that H-2 co-feeding positively affected dehydrogenation, improving the propylene formation rate. In situ spectroscopic characterization of TiH2 in the presence of H-2 indicated that partially dehydrogenated titanium hydrides are active for dehydrogenation.
• Synthesis of Zeolitic Ti, Zr-Substituted Vanadotungstates and Investigation of Their Catalytic Activities for Low Temperature NH3-SCR

  Meilin Tao, Satoshi Ishikawa, Zhenxin Zhang, Toru Murayama, Yusuke Inomata, Akiho Kamiyama, Ichika Nakaima, Yuan Jing, Shinya Mine, Kosuke Shimoda, Takashi Toyao, Ken Ichi Shimizu, Wataru Ueda

  ACS Catalysis 11 22 14016 - 14025 2021年11月19日 

  Microporous vanadotungstate (W4V3O19, VT-1) was constructed via the connection of [W4O16]8- cubane units with VO2+ linkers to form an LTA-zeolite-type crystal structure. We found that the VO2+ sites connecting the cubane units of VT-1 could be partially removed by an appropriate acid treatment without destroying its crystal structure. This process involved a redox reaction between the [W4O16]8- cubane units and VO2+ linkers, and V was removed as V5+ during the acid treatment. TiO2+ or ZrO2+ could be introduced into the VO2+ vacancies. The introduction of Ti or Zr substantially improved the thermal stability of VT-1 under oxidizing conditions. The catalytic activity toward the selective catalytic reduction of NOx with NH3 (NH3-SCR) was improved by the introduction of Ti or Zr.
• Factors determining surface oxygen vacancy formation energy in ternary spinel structure oxides with zinc.

  Yoyo Hinuma, Shinya Mine, Takashi Toyao, Takashi Kamachi, Ken-Ichi Shimizu

  Physical chemistry chemical physics : PCCP 23 41 23768 - 23777 2021年10月27日 

  Spinel oxides are an important class of materials for heterogeneous catalysis including photocatalysis and electrocatalysis. The surface O vacancy formation energy (EOvac) is a critical quantity for catalyst performance because the surface of metal oxide catalysts often acts as a reaction site, for example, in the Mars-van Krevelen mechanism. However, experimental evaluation of EOvac is very challenging. We obtained the EOvac for (100), (110), and (111) surfaces of normal zinc-based spinel oxides ZnAl2O4, ZnGa2O4, ZnIn2O4, ZnV2O4, ZnCr2O4, ZnMn2O4, ZnFe2O4, and ZnCo2O4. The most stable surface is (100) for all compounds. The smallest EOvac for a surface is the largest in the (100) surface except for ZnCo2O4. For (100) and (110) surfaces, there is a good correlation, over all spinels, between the smallest EOvac for the surface and bulk formation energy, while the ionization potential correlates well in (111) surfaces. Machine learning over EOvac of all surface sites in all orientations and for all compounds to find the important factors, or descriptors, that decide the EOvac revealed that bulk and surface-dependent descriptors are the most important, namely the bulk formation energy, a Boolean descriptor of whether the surface is (111) or not, and the ionization potential, followed by geometrical descriptors that are different in each O site.
• Mechanism of NH3-Selective Catalytic Reduction (SCR) of NO/NO2(Fast SCR) over Cu-CHA Zeolites Studied byIn Situ/OperandoInfrared Spectroscopy and Density Functional Theory

  Chong Liu, Grazia Malta, Hiroe Kubota, Takashi Toyao, Zen Maeno, Ken Ichi Shimizu

  Journal of Physical Chemistry C 125 40 21975 - 21987 2021年10月14日 

  In situ/operandoinfrared (IR) spectroscopy, kinetics, and density functional theory (DFT) calculations were combined to propose a comprehensive mechanistic model of the selective catalytic reduction (SCR) of the NO/NO2mixture by NH3, the so-called fast SCR, over Cu-CHA zeolites. Steady-state kinetics for standard and fast SCR over H-CHA and Cu-CHA show that the promotional effect of NO2on SCR is less significant for Cu-CHA than H-CHA, suggesting that the Brønsted acid site (BAS; H+OZ-) is important in fast SCR chemistry.In situIR experiments show that NO2disproportionates on Cu-CHA to NO+on the cation-exchange site (NO+OZ-) of CHA and NO3-on CuIIsites.OperandoIR studies under transient or temperature-programmed surface reaction conditions indicate that the NO+OZ-intermediate is reduced by NH3to yield N2below 200 °C, while NO3-on the CuIIsite is rather stable under NH3and is reduced by NO to afford NO+OZ-. BASs, rather than Cu sites, promote the side reactions via ammonium nitrate (NH4NO3). The dual-site (CuIIand BAS sites) catalytic mechanism of fast SCR was verified by DFT calculations. First, two NO2molecules are converted to a nitrous acid (HONO) intermediate and NO3-on the CuIIsite, which is then reduced by NO to afford HONO and regenerate the CuIIsite. HONO reacts with the BAS to afford NO+OZ-, which reacts with NH3to produce N2and H2O, via nitrosamide (NH2NO), along with the regeneration of the BAS.
• Lean NOx Reduction by In-Situ-Formed NH3 under Periodic Lean/Rich Conditions over Rhodium-Loaded Al-Rich Beta Zeolites

  Shunsaku Yasumura, Takashi Toyao, Zen Maeno, Ken-ichi Shimizu

  ACS CATALYSIS 11 19 12293 - 12300 2021年10月 

  Toward the rational design of new lean NOx reduction catalysts under periodic lean (NO + O-2) and rich (NO + H-2) cycle conditions, we studied the reactions of adsorbed NO and NH3 on Rh-exchanged Al-rich (Si/Al = 5) beta zeolites (Rh4 beta 5) under transient (lean. rich) and temperature ramping conditions. In situ infrared (IR) spectra of adsorbed species were collected while monitoring the outlet gas by mass spectrometry (MS) and another IR gas cell, enabling an operando analysis of the surface reactions. Dynamic changes in the catalyst structure were studied by X-ray absorption spectroscopy (XAS), H-2-temperature-programed reduction (TPR), and operando IR spectroscopy. Rh-0 metal clusters, Rh+, and Rh3+ species were copresent in the catalyst after H-2 reduction at 500 degrees C. Under NO or NO + O-2 flow, the Rh+ site (NO storage site) in the reduced Rh4 beta 5 captured NO in the form of [Rh(NO)(2)]+, which was stable under oxidative (lean) conditions. The captured NO was selectively reduced by H-2 to NH3. The in-situ-generated NH3 was captured by a Bronsted acid site (NH3 storage site). The captured NH3 reduced NO to N-2 in the next lean (NO + O-2) period. Finally, Rh4 beta 5 was applied to the lean de-NOx system under cyclic lean/rich conditions, accompanied by NOx reduction under periodic lean (0.1% NO + 2% O-2)/rich (0.1% NO + 2% H-2) cycles. The NOx trapped in the lean period is reduced to adsorbed NH3 in the rich period, which subsequently reduces NO to N-2 in the next lean period.
• Electroassisted Propane Dehydrogenation at Low Temperatures: Far beyond the Equilibrium Limitation

  Jianshuo Zhang, Ruoyun Ma, Hyungwon Ham, Ken-ichi Shimizu, Shinya Furukawa

  JACS AU 1 10 1688 - 1693 2021年10月 

  Propylene production by propane dehydrogenation (PDH) generally requires high temperatures due to thermodynamic equilibrium limitations. This study developed a novel type of catalytic system for low-temperature PDH by combining a surface protonics methodology with intermetallic active sites. By application of an electric current, the intermetallic Pt-In/TiO2 catalyst gave a propylene yield of 10.2% with high selectivity, even at 250 degrees C, where the thermodynamic equilibrium yield was only 0.15%. Electroassisted proton collisions with propane allowed an unusual reaction pathway for low-temperature PDH. Alloying of Pt with In drastically enhanced the activity and selectivity due to the increased electron density of Pt.
• Analogous Mechanistic Features of NH3-SCR over Vanadium Oxide and Copper Zeolite Catalysts

  Hiroe Kubota, Takashi Toyao, Zen Maeno, Yusuke Inomata, Toru Murayama, Naoto Nakazawa, Satoshi Inagaki, Yoshihiro Kubota, Ken Ichi Shimizu

  ACS Catalysis 11 17 11180 - 11192 2021年09月03日 

  Reduction/oxidation half-cycles of the selective catalytic reduction of NO with NH3(NH3-SCR) at 200 °C were investigated usingin situandoperandospectroscopies to propose a general mechanism for four different catalysts (TiO2-supported and bulk vanadium oxides and Cu-AFX and Cu-CHA zeolites). The reduction half-cycle is initiated by the reaction of NH3on Lewis acid sites [V(V) or Cu(II); L-NH3] and NO, followed by the gradual reaction of NH3on Brønsted acid sites (B-NH3) and NO; this results in the formation of V(IV) or Cu(I) and protons (H+) on the surface, along with N2and H2O. The UV-vis measurements for the reduction half-cycle indicate that N2is continuously generated until the surface V(V) or Cu(II) species is depleted. The subsequent reoxidation of the reduced catalysts under O2leads to the regeneration of V(V) or Cu(II) and the reaction of surface H+, yielding H2O (oxidation half-cycle). The higher consumption rates of B-NH3and L-NH3under NO + O2than those under NO, which has been previously reported in the literature, were explained based on the continuous reduction/oxidation of V(V)/V(IV) or Cu(II)/Cu(I) where the regenerated V(V) or Cu(II) site is reused in the subsequent (second) reduction half-cycle. Namely, upon the recovery of V(V) or Cu(II)viareoxidation, the leftover B-NH3species react with the supplied NO to yield N2; this suggests that B-NH3is not a spectator but a reservoir of NH3to participate in the second reduction half-cycle possiblyviathe migration of NH3or HONO species. These results provide comprehensive evidence of the general mechanism of NH3-SCR, which was found to be applicable to both V and Cu catalysts.
• Doubly Decorated Platinum-Gallium Intermetallics as Stable Catalysts for Propane Dehydrogenation.

  Yuki Nakaya, Feilong Xing, Hyungwon Ham, Ken-Ichi Shimizu, Shinya Furukawa

  Angewandte Chemie (International ed. in English) 60 36 19715 - 19719 2021年09月01日 

  Propane dehydrogenation (PDH) is a promising chemical process that can satisfy the increasing global demand for propylene. However, the Pt-based catalysts that have been reported thus far are typically deactivated at ≥600 °C by side reactions and coke formation. Thus, such catalysts possess an insufficient life. Herein, we report a novel catalyst design concept, namely, the double decoration of PtGa intermetallics by Pb and Ca, which synergize the geometric and electronic promotion effects on the catalyst stability, respectively. Pb is deposited on the three-fold Pt3 sites of the PtGa nanoparticles to block them, whereas Ca, which affords an electron-enriched single-atom-like Pt1 site, is placed around the nanoparticles. Thus, PtGa-Ca-Pb/SiO2 exhibits an outstandingly high catalytic stability, even at 600 °C (kd =0.00033 h-1 , τ=3067 h), and almost no deactivation of the catalyst was observed for up to 1 month for the first time.
• Analysis of Updated Literature Data up to 2019 on the Oxidative Coupling of Methane Using an Extrapolative Machine-Learning Method to Identify Novel Catalysts

  Shinya Mine, Motoshi Takao, Taichi Yamaguchi, Takashi Toyao, Zen Maeno, S. M.A. Hakim Siddiki, Satoru Takakusagi, Ken ichi Shimizu, Ichigaku Takigawa

  ChemCatChem 13 16 3636 - 3655 2021年08月20日 

  We have constructed and analyzed an updated dataset consisting of 4759 experimental datapoints for the oxidative coupling of methane (OCM) reaction based on literature data reported before 2020 (∼2019) using machine learning (ML) methods. Several ML methods, including random forest regression (RFR), extra trees regression (ETR), and gradient boosting regression with XGBoost (XGB), were used in conjunction with our proposed approach, in which elemental features are used as input representations rather than inputting the catalyst compositions directly. A recent research trend, namely, the extensive exploration of Mn/Na2WO4/SiO2 catalyst systems in recent years due to their high activity and durability, was clearly reflected in the dataset analysis. An ML model for the prediction of the reaction outcome (C2 yield) was successfully developed, and feature importance scores and SHapley Additive exPlanations (SHAP) values were calculated based on ETR and XGB, respectively, to identify the input variables with the greatest influence on the catalyst performance and observe how these important variables affect the C2 yield in the OCM. The discovery and optimization of catalytic processes using ML as a “surrogate” model were explored, and promising catalytic system candidates for the OCM reaction were identified. Notably, the developed ML model predicted catalysts containing elements that do not appear in the OCM dataset. This clearly demonstrates desirably high potential of our ML model to enable extrapolative predictions for ML-aided future catalysis research.
• Surface activation by electron scavenger metal nanorod adsorption on TiH2, TiC, TiN, and Ti2O3.

  Yoyo Hinuma, Shinya Mine, Takashi Toyao, Zen Maeno, Ken-Ichi Shimizu

  Physical chemistry chemical physics : PCCP 23 31 16577 - 16593 2021年08月12日 

  Metal/oxide support perimeter sites are known to provide unique properties because the nearby metal changes the local environment on the support surface. In particular, the electron scavenger effect reduces the energy necessary for surface anion desorption, and thereby contributes to activation of the (reverse) Mars-van Krevelen mechanism. This study investigated the possibility of such activation in hydrides, carbides, nitrides, and sulfides. The work functions (WFs) of known hydrides, carbides, nitrides, oxides, and sulfides with group 3, 4, or 5 cations (Sc, Y, La, Ti, Zr, Hf, V, Nb, and Ta) were calculated. The WFs of most hydrides, carbides, and nitrides are smaller than the WF of Ag, implying that the electron scavenger effect may occur when late transition metal nanoparticles are adsorbed on the surface. The WF of oxides and sulfides decreases when reduced. The surface anion vacancy formation energy correlates well with the bulk formation energy in carbides and nitrides, while almost no correlation is found in hydrides because of the small range of surface hydrogen vacancy formation energy values. The electron scavenger effect is explicitly observed in nanorods adsorbed on TiH2 and Ti2O3; the surface vacancy formation energy decreases at anion sites near the nanorod, and charge transfer to the nanorod happens when an anion is removed at such sites. Activation of hydrides, carbides, and nitrides by nanorod adsorption and screening support materials through WF calculation are expected to open up a new category of supported catalysts.
• Alkyl decorated metal-organic frameworks for selective trapping of ethane from ethylene above ambient pressures.

  Andreas Schneemann, Yuan Jing, Jack D Evans, Takashi Toyao, Yuh Hijikata, Yuichi Kamiya, Ken-Ichi Shimizu, Nicholas C Burtch, Shin-Ichiro Noro

  Dalton transactions (Cambridge, England : 2003) 50 30 10423 - 10435 2021年08月04日 

  The trapping of paraffins is beneficial compared to selective olefin adsorption for adsorptive olefin purification from a process engineering point of view. Here we demonstrate the use of a series of Zn2(X-bdc)2(dabco) (where X-bdc2- is bdc2- = 1,4-benzenedicarboxylate with substituting groups X, DM-bdc2- = 2,5-dimethyl-1,4-benzenedicarboxylate or TM-bdc2- = 2,3,5,6-tetramethyl-1,4-benzenedicarboxylate and dabco = diazabicyclo[2.2.2.]octane) metal-organic frameworks (MOFs) for the adsorptive removal of ethane from ethylene streams. The best performing material from this series is Zn2(TM-bdc)2(dabco) (DMOF-TM), which shows a high ethane uptake of 5.31 mmol g-1 at 110 kPa, with a good IAST selectivity of 1.88 towards ethane over ethylene. Through breakthrough measurements a high productivity of 13.1 L kg-1 per breakthrough is revealed with good reproducibility over five consecutive cycles. Molecular simulations show that the methyl groups of DMOF-TM are forming a van der Waals trap with the methylene groups from dabco, snuggly fitting the ethane. Further, rarely used high pressure coadsorption measurements, in pressure regimes that most scientific studies on hydrocarbon separation on MOFs ignore, reveal an increase in ethane capacity and selectivity for binary mixtures with increased pressures. The coadsorption measurements reveal good selectivity of 1.96 at 1000 kPa, which is verified also through IAST calculations up to 3000 kPa. This study overall showcases the opportunities that pore engineering by alkyl group incorporation and pressure increase offer to improve hydrocarbon separation in reticular materials.
• Roles of the basic metals La, Ba, and Sr as additives in Al2O3-supported Pd-based three-way catalysts

  Yuan Jing, Gang Wang, Kah Wei Ting, Zen Maeno, Kazumasa Oshima, Shigeo Satokawa, Shuhei Nagaoka, Ken-ichi Shimizu, Takashi Toyao

  JOURNAL OF CATALYSIS 400 387 - 396 2021年08月 

  Three-way catalytic converters are widely used to regulate emissions from gasoline-powered vehicles. Although significant effort over the past 40 years has resulted in the discovery of several metal additives that improve the thermal stability of three-way catalysts (TWCs), their effects on the actual catalytic process have not been studied systematically. The present work examines the roles of the typical basic metal additives La, Ba, and Sr in Pd-based TWC systems, using various spectroscopic and kinetic studies. Metallic Pd-0 species on Sr/Al2O3 and Ba/Al2O3 supports were found to be more electron-rich than those on pristine Al2O3, whereas those on La/Al2O3 were more electron-deficient. Consequently, Pd/La/Al2O3 showed a lessened CO poisoning effect during NO reduction reactions. Evaluations were performed using powdered catalysts as well as monolithic honeycomb catalysts under conditions simulating actual use. Pd/La/Al2O3 was observed to promote the catalytic reduction of NO most efficiently, while Pd/Ba/Al2O3 exhibited the highest activity for the oxidations of CO and C3H6. The present data suggest that the optimal metal additive for a Pd-based TWC will be determined by the specific application. The selection of such metals should take into account not only the stability but also the promotional effect during the exhaust purification process. (C) 2021 Elsevier Inc. All rights reserved.
• Local structure and NO adsorption/desorption property of Pd2+ cations at different paired Al sites in CHA zeolite

  Shunsaku Yasumura, Taihei Ueda, Hajime Ide, Katsumasa Otsubo, Chong Liu, Nao Tsunoji, Takashi Toyao, Zen Maeno, Ken-ichi Shimizu

  PHYSICAL CHEMISTRY CHEMICAL PHYSICS 23 39 22273 - 22282 2021年08月 

  Recently, Pd-exchanged CHA zeolites (Pd-CHA) have attracted attention as promising passive NOx adsorbers (PNAs) for reducing NOx emissions during the cold start period of a vehicle engine. In this work, the relationship between the local structures and the NO adsorption/desorption properties of the Pd cations in CHA zeolites was investigated. Pd cation formation and NO adsorption were theoretically explored by density functional theory (DFT) calculations for different paired Al sites in six-/eight-membered rings (6MR/8MR). Furthermore, we prepared a series of Pd-CHAs with different Pd loadings (0.5-5.4 wt%) and evaluated their NO adsorption/desorption properties by in situ infrared (IR) spectroscopy and temperature-programmed desorption (TPD) measurements. The increase in the Pd loading resulted in a shift in the NO desorption temperature toward a higher temperature regime. This phenomenon was ascribed to the increase in the proportion of less stable Pd cations, resulting in improved NO adsorption. Furthermore, the effect of Al distribution on the NO adsorption property of Pd-CHA was examined using CHA zeolites containing different proportions of paired Al sites in 6MR while maintaining similar Si/Al ratios (Si/Al = 12.0-16.5). The present study, based on a combination of theoretical and experimental techniques, shows that the NO adsorption/desorption properties over Pd-CHA can be tuned by controlling the Pd loading amount and the type of paired Al sites.
• Selective catalytic reduction of NO over Cu-AFX zeolites: mechanistic insights fromin situ/operandospectroscopic and DFT studies

  Chong Liu, Hiroe Kubota, Takehiro Amada, Takashi Toyao, Zen Maeno, Masaru Ogura, Naoto Nakazawa, Satoshi Inagaki, Yoshihiro Kubota, Ken Ichi Shimizu

  Catalysis Science and Technology 11 13 4459 - 4470 2021年07月07日 

  In situ/operandospectroscopic experiments and DFT calculations were combined to study the selective catalytic reduction of NO with NH3(NH3-SCR) over Cu-AFX zeolites. Transient experiments (in situ/operandoXANES, IR, and UV-vis) on the reduction half cycle show that the NH3coordinated to the Cu(ii) center reacts with NO to produce N2and H2O, and simultaneously Cu(ii) is reduced to Cu(i). On the other hand, transient experiments on the oxidation half cycle indicate that the oxidation of Cu(i) to Cu(ii) species occurs with O2as the sole oxidant. DFT calculations suggest plausible pathways for the oxidative activation of Cu(i) by O2as the only oxidant. It is proposed that the oxidation of Cu(i) by O2as the exclusive oxidant rather than the NO-assisted oxidation plays the key role in the standard NH3-SCR reaction at low temperatures.
• In Situ/Operando IR and Theoretical Studies on the Mechanism of NH3-SCR of NO/NO2over H-CHA Zeolites

  Chong Liu, Grazia Malta, Hiroe Kubota, Kenichi Kon, Takashi Toyao, Zen Maeno, Ken Ichi Shimizu

  Journal of Physical Chemistry C 125 25 13889 - 13899 2021年07月01日 

  The mechanism of selective catalytic reduction (SCR) of a NO/NO2mixture by NH3(fast SCR) over H-CHA zeolites was revealed by in situ/operando IR spectroscopy and DFT calculations. Kinetic results show that the rate of fast SCR is 2 orders of magnitude higher than that for standard SCR by H-CHA. Combined experimental and computational results show a complete mechanism of fast SCR initiated by the disproportionation of NO2into adsorbed NO+and NO3-species. NO+reacts with NH3to produce N2and H2O, while NO3-reacts with NH3on Brønsted acid sites (NH4+) to yield NH4NO3. In the presence of NO, NH4NO3is reduced by NO to afford NH4NO2, which then decomposes into N2and H2O, while thermal decomposition of NH4NO3yields N2O and H2O in the absence of NO. The activation and reaction energies for all of the elementary steps are computed by DFT, which support the experimentally proposed mechanism of fast SCR over H-CHA. During the SCR process where NO2participated, the Brønsted acid sites of the zeolite play an essential catalytic role in key elementary reactions.
• Reverse water-gas shift reaction over Pt/MoOx/TiO2: reverse Mars-van Krevelen mechanismviaredox of supported MoOx

  Shinya Mine, Taichi Yamaguchi, Kah Wei Ting, Zen Maeno, S. M.A.H. Siddiki, Kazumasa Oshima, Shigeo Satokawa, Ken Ichi Shimizu, Takashi Toyao

  Catalysis Science and Technology 11 12 4172 - 4180 2021年06月21日 

  The reverse water-gas shift (RWGS) reaction is a promising catalytic route for reducing CO2emissions because its product, CO, is a key intermediate in various industrialized catalytic processes that produce fuels and chemicals. We describe herein a MoOx/TiO2-supported Pt catalyst (Pt(3)/MoOx(15)/TiO2; Pt loading = 3 wt%, MoO3loading = 15 wt%) that promotes the RWGS reaction at low temperature (200-300 °C) with high activity and selectivity. The catalytic performance for both CO2conversion and selectivity of Pt(3)/MoOx(15)/TiO2is better than those of Pt catalysts on other supports and other metal catalysts supported on MoOx(15)/TiO2, as well as Cu- and Fe-Cr-based industrial catalysts. Moreover, results ofoperandoX-ray absorption spectroscopy studies show that the reaction takes placeviathe reverse Mars-van Krevelen mechanism where H2acts as a reducing agent to create oxygen vacancies on the supported Mo oxide species that are filled by CO2as an oxidizing agent.
• Silica-decorated Ni-Zn alloy as a highly active and selective catalyst for acetylene semihydrogenation

  Wiyanti F. Simanullang, Jiamin Ma, Ken Ichi Shimizu, Shinya Furukawa

  Catalysis Science and Technology 11 12 4016 - 4020 2021年06月21日 

  A silica-decoration methodology was applied to a Ni-Zn alloy for developing active and selective acetylene semihydrogenation. Ni-Zn alloy nanoparticles on SiO2were further decorated by additional silica, which significantly increased the acetylene conversion (15-97%) without lowering the ethylene selectivity (ca.80%) at 200 °C.
• Flow reactor approach for the facile and continuous synthesis of efficient Pd@Pt core-shell nanoparticles for acceptorless dehydrogenative synthesis of pyrimidines from alcohols and amidines

  Sharmin Sultana Poly, Yuta Hashiguchi, Asima Sultana, Isao Nakamura, Ken ichi Shimizu, Shunsaku Yasumura, Tadahiro Fujitani

  Applied Catalysis A: General 619 2021年06月05日 

  Carbon supported Pd@Pt core-shell nanoparticles catalyst was prepared in a flow reactor toachieve enhanced catalytic activities with low Pt loading for the acceptorless dehydrogenative synthesis of pyrimidines. Spectroscopic (XAS analysis) and microscopic (HAADF-STEM) techniques reveled that the core-shell structure was formed by the applied preparation method. The Pd@Pt/PVP (polyvinylpyrrolidone)/C catalyst showed the activity for the three component one pot synthesis of pyrimidines through a series of consecutive reactions including oxidation of alcohols, C[sbnd]C, and C[sbnd]N coupling, followed by heterocyclization and dehydrogenation employing various primary alcohols, secondary alcohols, and amidines. The reaction mechanism on Pd@Pt/PVP/C catalyst was explored by comparison with the control experiments.
• Catalytic Methylation of m-Xylene, Toluene, and Benzene Using CO2 and H-2 over TiO2-Supported Re and Zeolite Catalysts: Machine-Learning-Assisted Catalyst Optimization

  Kah Wei Ting, Haruka Kamakura, Sharmin S. Poly, Motoshi Takao, S. M. A. Hakim Siddiki, Zen Maeno, Koichi Matsushita, Ken-ichi Shimizu, Takashi Toyao

  ACS CATALYSIS 11 9 5829 - 5838 2021年05月 

  Catalytic methylation of aromatic hydrocarbons using CO2 and H-2 as a methylating agent was conducted over a combination of TiO2-supported Re (Re(1)/TiO2; Re = 1 wt %) and H-beta (SiO2/Al2O3 = 40) in a batch reactor. Catalytic methylation of m-xylene was performed, and this catalyst combination demonstrated excellent performance for the synthesis of methylbenzenes, giving a high yield of total methylated products (10 and 57%, as calculated on the basis of CO2 and m-xylene, respectively), while generating relatively small amounts of by-products such as demethylated and dearomatized products as well as CO and CH4 in the gas phase under the investigated reaction conditions (p(CO2) = 1 MPa, p(H2) = 5 MPa, T = 240 degrees C, t = 20 h). Our catalysts were also found to perform well for the methylation of toluene, providing a high yield and high selectivity for methylated products compared with the other investigated catalyst combinations. In addition to conducting conventional-type catalyst research, we used a data science approach based on machine learning techniques to identify important input variables that govern the catalytic performance, enabling optimization of the catalyst for the methylation reaction. Compared with the catalysts optimized using the conventional approach, the improved Re/TiO2 catalyst with a Re loading amount of 1.8 wt %, which was optimized with the aid of ML, exhibited greater activity toward the methylation of benzene using CO2/H-2.
• Hydrolysis of amides to carboxylic acids catalyzed by Nb2O5

  S. M. A. Hakim Siddiki, Md. Nurnobi Rashed, Abeda Sultana Touchy, Md. A. R. Jamil, Yuan Jing, Takashi Toyao, Zen Maeno, Ken-ichi Shimizu

  CATALYSIS SCIENCE & TECHNOLOGY 11 5 1949 - 1960 2021年03月 

  Hydrolysis of amides to carboxylic acids is an industrially important reaction but is challenging due to the difficulty of cleaving the resonance stabilized amidic C-N bond. Twenty-three heterogeneous and homogenous catalysts were examined in the hydrolysis of acetamide. Results showed that Nb2O5 was the most effective heterogeneous catalyst with the greatest yield of acetic acid. A series of Nb2O5 catalysts calcined at various temperatures were characterized and tested in the hydrolysis of acetamide to determine the effects of crystal phase and surface properties of Nb2O5 on catalytic performance. The high catalytic performance observed was attributed mainly to the facile activation of the carbonyl bond by Lewis acid sites that function even in the presence of basic inhibitors (NH3 and H2O). The catalytic studies showed the synthetic advantages of the present method, such as simple operation, catalyst recyclability, additive free, solvent free, and wide substrate scope (>40 examples; up to 95% isolated yield).
• High dimensionally structured W-V oxides as highly effective catalysts for selective oxidation of toluene

  Toru Murayama, Satoshi Ishikawa, Norihito Hiyoshi, Yoshinori Goto, Zhenxin Zhang, Takashi Toyao, Ken-ichi Shimizu, Shutoku Lee, Wataru Ueda

  CATALYSIS TODAY 363 60 - 66 2021年03月 

  High dimensionally structured W-V-O catalysts (HDS-WVO) were synthesized by hydrothermal method and catalyst structures were investigated by HAADF-STEM analysis. HDS-WVO were rod-shaped crystals and the cross-sections were constituted by W6O21 pentagonal units and MO6 octahedra (M = V, W), forming heptagonal and hexagonal channels. HDS-WVO catalysts showed excellent catalytic performance for selective oxidation of toluene to benzoic acid, and the activity and the selectivity to benzoic acid were superior to those of state-of-theart catalysts. After the ion exchange using Cs+, the catalytic activity over HDS-WVO was significantly decreased. Since HAADF-STEM analysis and N-2 adsorption revealed that Cs+ was located mainly at the heptagonal channel of HDS-WVO, it can be concluded that toluene oxidation takes place at the heptagonal channel site of HDS-WVO.
• Silica-Decoration Boosts Ni Catalysis for (De)hydrogenation: Step-Abundant Nanostructures Stabilized by Silica

  Hyungwon Ham, Wiyanti F. Simanullang, Yasuharu Kanda, Yu Wen, Ayako Hashimoto, Hideki Abe, Ken-ichi Shimizu, Shinya Furukawa

  CHEMCATCHEM 13 5 1306 - 1310 2021年03月 

  Ni nanoparticles supported on SiO2 were decorated with additional SiOx species by impregnation with tetraethoxysilane (Si(OEt)(4)). The combination of electron microscopy, infrared analysis, and density functional theory (DFT) calculations revealed that the SiOx-decoration made the surface morphology of Ni nanoparticles highly rough and step-abundant due to the significant stabilization of low-coordination-number sites. The SiOx-decorated Ni exhibited 50 times higher catalytic activity for the dehydrogenation of methylcyclohexane to toluene than pure Ni. DFT calculations revealed that the Ni(211) step sites had a more favorable C-H activation than Ni(111) terrace sites and well reproduced the experimental apparent activation energies.
• Selective catalytic reduction of NO with NH3 over Cu-exchanged CHA, GME, and AFX zeolites: a density functional theory study

  Pei Zhao, Bundet Boekfa, Ken-ichi Shimizu, Masaru Ogura, Masahiro Ehara

  CATALYSIS SCIENCE & TECHNOLOGY 11 5 1780 - 1790 2021年03月 

  Density functional theory calculations have been applied to study the selective catalytic reduction of NO by NH3 over the Cu-exchanged zeolites with cha, gme, and aft cages. The Cu-I, Cu-II, and [Cu-II(OH)](+) ions are considered as the active sites to study both the reduction and oxidation processes during the catalytic cycle. In the case of the reduction process, the NH2NO formation at the [Cu-II(OH)](+) site possesses high barriers in the three frameworks, while the lower barriers are found at the Cu-II site. Importantly, it is found that the barriers are largely decreased at the solvated [Cu-II(NH3)(4)](2+) site for the cha and aft frameworks, while the barrier is only slightly decreased for the gme cage. As for the oxidation, the nitrate formation has similar reaction barriers at the Cu-I site of the three frameworks, which are lower than the following nitrite formation. In particular, the smallest gme cage possesses the highest barrier for the nitrite formation. Calculations on the O-2 activation by the NH3-solvated Cu dimer revealed that the cha and aft cages have better performance than the gme cage, and the much smaller adsorption energy of O-2 in the gme cage indicates the unfavorable O-2 insertion. Therefore, the selectivity caused by the cage size is identified during the reaction process, and the cha and aft cages are more favorable.
• Effect of oxygen vacancies on adsorption of small molecules on anatase and rutile TiO2surfaces: A frontier orbital approach

  Nobutsugu Hamamoto, Toshinobu Tatsumi, Motoshi Takao, Takashi Toyao, Yoyo Hinuma, Ken Ichi Shimizu, Takashi Kamachi

  Journal of Physical Chemistry C 125 7 3827 - 3844 2021年02月25日 

  Adsorption is a critical step in the initial stage of a catalytic reaction. Oxygen vacancies often become a central topic of discussion with respect to the reaction mechanism on metal oxide surfaces because oxygen vacancies change the surface electronic properties and affect the adsorption process. In this study, we use firstprinciples calculations and regression analyses to investigate the effect of oxygen vacancies on a metal oxide surface on the adsorption of small molecules. We adopt the anatase (101) and rutile (110) TiO2 surfaces as research targets. The calculation results show that the removal of an oxygen atom causes a large difference in the electronic structure due to the presence of two unpaired electrons. Our previous study showed that the adsorption energy of a defect-free surface is linearly correlated with the energy of the highest occupied molecular orbital for small adsorbed molecules. In the case of a defective anatase surface, we found that the energy of the lowest unoccupied molecular orbital also plays an important role in enhancing the adsorption of small molecules, especially those with an unpaired electron. Notably, our results demonstrate that hardness is a prime descriptor to explain the adsorption of various molecules by TiO2 surfaces.
• Transformation of Bulk Pd to Pd Cations in Small-Pore CHA Zeolites Facilitated by NO.

  Shunsaku Yasumura, Hajime Ide, Taihei Ueda, Yuan Jing, Chong Liu, Kenichi Kon, Takashi Toyao, Zen Maeno, Ken-Ichi Shimizu

  JACS Au 1 2 201 - 211 2021年02月22日 

  Atomic dispersion of metal species has attracted attention as a unique phenomenon that affects adsorption properties and catalytic activities and that can be used to design so-called single atom materials. In this work, we describe atomic dispersion of bulk Pd into small pores of CHA zeolites. Under 4% NO flow at 600 °C, bulk Pd metal on the outside of CHA zeolites effectively disperses, affording Pd2+ cations on Al sites with concomitant formation of N2O, as revealed by microscopic and spectroscopic characterizations combined with mass spectroscopy. In the present method, even commercially available submicrosized Pd black can be used as a Pd source, and importantly, 4.1 wt % of atomic Pd2+ cations, which is the highest loading amount reported so far, can be introduced into CHA zeolites. The structural evolution of bulk Pd metal is also investigated by in situ X-ray absorption spectroscopy (XAS) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), as well as ab initio thermodynamic analysis using density functional theory (DFT) calculations.
• AFX Zeolite for Use as a Support of NH3-SCR Catalyst Mining through AICE Joint Research Project of Industries–Academia–Academia

  Masaru Ogura, Yumiko Shimada, Takeshi Ohnishi, Naoto Nakazawa, Yoshihiro Kubota, Toshiyuki Yokoi, Masahiro Ehara, Kenichi Shimizu, Nao Tsunoji

  Catalysts 11 2 163 - 163 2021年01月25日 

  This paper introduces a joint industries–academia–academia research project started by researchers in several automobile companies and universities working on a single theme. Our first target was to find a zeolite for NH3-SCR, that is, zeolite mining. Zeolite AFX, having the same topology of SSZ-16, was found to be the one of the zeolites. SSZ-16 can be synthesized by using an organic structure-directing agent such as 1,1′-tetramethylenebis(1-azonia-4-azabicyclo[2.2.2]octane; Dab-4, resulting in the formation of Al-rich SSZ-16 with Si/Al below five. We found that AFX crystallized by use of N,N,N′,N′-tetraethylbicyclo[2.2.2]oct-7-ene-2,3:5,6-dipyrrolidinium ion, called TEBOP in this study, had the same analog as SSZ-16 having Si/Al around six and a smaller particle size than SSZ-16. The AFX demonstrated a high performance for NH3-SCR as the zeolitic support to load a large number of divalent Cu ionic species with high hydrothermal stability.
• Bulk tungsten-substituted vanadium oxide for low-temperature NOx removal in the presence of water.

  Yusuke Inomata, Hiroe Kubota, Shinichi Hata, Eiji Kiyonaga, Keiichiro Morita, Kazuhiro Yoshida, Norihito Sakaguchi, Takashi Toyao, Ken-Ichi Shimizu, Satoshi Ishikawa, Wataru Ueda, Masatake Haruta, Toru Murayama

  Nature communications 12 1 557 - 557 2021年01月25日 

  NH3-SCR (selective catalytic reduction) is important process for removal of NOx. However, water vapor included in exhaust gases critically inhibits the reaction in a low temperature range. Here, we report bulk W-substituted vanadium oxide catalysts for NH3-SCR at a low temperature (100-150 °C) and in the presence of water (~20 vol%). The 3.5 mol% W-substituted vanadium oxide shows >99% (dry) and ~93% (wet, 5-20 vol% water) NO conversion at 150 °C (250 ppm NO, 250 ppm NH3, 4% O2, SV = 40000 mL h-1 gcat-1). Lewis acid sites of W-substituted vanadium oxide are converted to Brønsted acid sites under a wet condition while the distribution of Brønsted and Lewis acid sites does not change without tungsten. NH4+ species adsorbed on Brønsted acid sites react with NO accompanied by the reduction of V5+ sites at 150 °C. The high redox ability and reactivity of Brønsted acid sites are observed for bulk W-substituted vanadium oxide at a low temperature in the presence of water, and thus the catalytic cycle is less affected by water vapor.
• Kinetic and spectroscopic insights into the behaviour of Cu active site for NH3-SCR over zeolites with several topologies

  Yusuke Ohata, Hiroe Kubota, Takashi Toyao, Ken-ichi Shimizu, Takeshi Ohnishi, Takahiko Moteki, Masaru Ogura

  Catalysis Science & Technology 11 8 2718 - 2733 2021年 

  Zeolite topology has a great effect on the dependence of NH₃-SCR rates over Cu–zeolites at 473 K on Cu density. It is revealed by the time-resolved UV-vis measurements that zeolites mainly affect the oxidation property of Cu ion by O₂.

• Reverse Water-Gas Shift Reaction via Redox of Re Nanoclusters Supported on TiO2

  Kah Wei Ting, Zen Maeno, S. M. A. Hakim Siddiki, Ken-ichi Shimizu, Takashi Toyao

  CHEMISTRY LETTERS 50 1 158 - 161 2021年01月 

  A Re catalyst supported on TiO2 (Re/TiO2) promoted the reverse water-gas shift (RWGS) reaction, exhibiting high selectivity toward CO. Operando X-ray absorption near edge structure (XANES) measurements revealed that the redox of Re species was responsible for promotion of the reaction. The Re/TiO2 catalyst also possessed remarkable durability and maintained >99.9% CO selectivity for more than 1000 h.
• Lean NOx Capture and Reduction by NH3 via NO+ Intermediates over H-CHA at Room Temperature

  Shunsaku Yasumura, Chong Liu, Takashi Toyao, Zen Maeno, Ken-ichi Shimizu

  JOURNAL OF PHYSICAL CHEMISTRY C 125 3 1913 - 1922 2021年01月 

  The oxidation of NO to NO2 and the subsequent reduction by NH3 via a NO+ intermediate over a proton-type chabazite zeolite (H-CHA) were investigated by the combination of in situ infrared (IR) spectroscopy and density functional theory (DFT) calculations. The in situ IR spectral results indicate that the NO' species formed under a flow of NO + O-2 at 27-250 degrees C are more stable at lower temperatures over both H-CHA and copper-cation-exchanged CHA zeolite (Cu-CHA). The Arrhenius plot (T = 27-120 degrees C) shows a negative apparent activation barrier energy (-11.5 kJ mol(-1)) for the formation of NO+ species under the NO + O(2 )flow over H-CHA. The time course of the IR spectra at 27 degrees C shows that NO is oxidized by O-2 to NO2 and then further converted via N2O4 to NO+ and NO3. The subsequent exposure to NH3 at 27 degrees C reduces the NO species to N-2. DFT calculations revealed that Bronsted acid sites in zeolite pores promote the dissociation of N2O4 intermediates into NO and NO3- species with a low activation barrier (15 kJ mol(-1)). Moreover, the computed activation barrier for the reduction of NO+ species by NH3 was considerably low (6 kJ mol(-1)). The experimental and theoretical results of this study demonstrate the high potential of Cu-free H-CHA zeolites for promoting lean NOx capture to form NO+ species and the subsequent reduction by NH3 at room temperature.
• Changes in Surface Oxygen Vacancy Formation Energy at Metal/Oxide Perimeter Sites: A Systematic Study on Metal Nanoparticles Deposited on an In2O3(111) Support

  Yoyo Hinuma, Takashi Toyao, Nobutsugu Hamamoto, Motoshi Takao, Ken-ichi Shimizu, Takashi Kamachi

  JOURNAL OF PHYSICAL CHEMISTRY C 124 50 27621 - 27630 2020年12月 

  Metal/oxide support perimeter sites can provide unique properties because the local environment on the support surface is changed by the nearby metal. This study modeled perimeter sites when metal nanorods were adsorbed in lieu of nanoparticles on the (111) surface of an In2O3 support. The metal element M was one of Ag, Au, Cu, Ir, Pd, Pt, and Re. Changes in the surface oxygen vacancy formation energy (EOvac) with nanorod adsorption were evaluated using systematic first-principles calculations under the same approximations and conditions and were found to be driven by two major factors. First, if the Fermi energy of the metal is deeper than the defect energy level of surface O vacancies, the metal may act as an electron scavenger to accept excess electrons upon O removal from sites close to the metal. The minimum EOvac for each M correlated very well with the Bader charge transfer to the nanorod upon O removal. The effect of geometrical relaxation of the nanorod after O removal was not found because there was barely any spontaneous rearrangement of nanorod atoms after O removal. As a consequence, the minimum EOvac in a surface tends to decrease with the increasing work function of M. Second, among different O sites on the same surface, EOvac is lower in O sites when there are interface states with the adsorbed metal at energy levels higher than the valence band of the support. These insights would help in planning strategies to obtain active O sites.
• PdIn-Based Pseudo-Binary Alloy as a Catalyst for NOx Removal under Lean Conditions

  Jaewan Jeon, Hyungwon Ham, Feilong Xing, Yuki Nakaya, Ken-ichi Shimizu, Shinya Furukawa

  ACS CATALYSIS 10 19 11380 - 11384 2020年10月 

  Developing a noble-metal-based catalyst that works effectively for NOx removal in the presence of excess O-2 is still a big challenge in catalytic chemistry for exhaust gas purification. To overcome this challenge, in this study, we designed and prepared a nanoparticulate (Pd1-xPtx)In pseudobinary alloy using Al2O3 and CeO2 supports, where a portion of Pd was replaced with Pt to improve the oxidation tolerance of In during NOx reduction under lean conditions. Multiple characterization techniques were used to confirm the formation of the desired pseudobinary alloy phase. The prepared Pd-Pt-In/CeO2 catalyst exhibited high NO conversion to N-2 in NO-CO-O-2 reaction with a wide range of oxygen concentrations including lean conditions (80%-100%, 0.75 <= lambda <= 1.5, 350 degrees C) and retained its catalytic performance during rich-lean cycles.
• Catalyst design concept based on a variety of alloy materials: a personal account and relevant studies

  Shinya Furukawa, Takayuki Komatsu, Ken-ichi Shimizu

  JOURNAL OF MATERIALS CHEMISTRY A 8 31 15620 - 15645 2020年08月 

  An overview of our recent advances in the development of highly efficient alloy materials for catalytic applications (intermetallic compounds, pseudo-binary, solid-solution, and single-atom alloys, and their derivatives) is provided as a personal account for the design of alloy-based catalysts. A series of important and emerging alloy materials and derivatives developed by other researchers for catalytic processes, such as Heusler alloys, high-entropy alloys, and rooted catalysts, are also introduced to cover a wide variety of such catalytic materials. The presented alloy materials are classified into (1) ordered, (2) disordered (random), and (3) precursors for nanocomposites, and each of them is further classified into subcategories based on their structure differences. The role of the metal elements, structural factors, and electronic properties in enhanced catalysis is also briefly explained by atomic scale interpretation.
• A CHA zeolite supported Ga-oxo cluster for partial oxidation of CH4 at room temperature

  Shunsaku Yasumura, Mengwen Huang, Xiaopeng Wu, Chong Liu, Takashi Toyao, Zen Maeno, Ken-ichi Shimizu

  CATALYSIS TODAY 352 118 - 126 2020年08月 

  A catalytic system for activation of CH4 under mild conditions is in high demand. In this study, Ga-oxo clusters in CHA zeolites were prepared by reductive solid-state ion-exchange followed by O-2 treatment. Formation of the Ga-oxo clusters was demonstrated using X-ray absorption fine structure (XAFS) measurements. Plausible models of the cluster were developed by using an ab initio thermodynamic analysis. Importantly, the CHA zeolite-supported Ga-oxo clusters promote partial oxidation of CH4 to yield adsorbed formaldehyde and formic acid. The results of density functional theory (DFT) calculations, designed to gain information about the mechanism of the process, show that the Z(2)[Ga-2(O)(OH)(2)] is likely the most active cluster for C-H bond activation of CH4. Observations made in this experimental and theoretical effort demonstrate that main-group metal-oxo clusters have the potential of serving as active species for transformations of CH4.
• Kinetic modeling of steady-state NH3-SCR over a monolithic Cu-CHA

  永島渉, 柴田元, 柴山直己, 小橋好充実, 小川英之, 清水研一

  Catalysis today 352 352 237 - 242 2020年08月 [査読有り][通常論文]
   

  A steady-state kinetic model for the NH3-SCR and NH3 oxidation by a monolithic Cu-exchanged chabazite (Cu-CHA) catalyst has been developed by a combination of flow reactor experiments and kinetic modeling with an in-house computational code. Arrhenius parameters for NH3-SCR and NH3 oxidation and reaction orders with respect to H2O and O2 are collected using a Cu-CHA catalyst coated onto a honeycomb cordierite substrate. While H2O is shown to affect NH3-SCR and low temperature NH3 oxidation to N2 negatively, it promotes high temperature NH3 oxidation to NO. By a combination of calculations for heat and mass transfer and the parameters of the monolithic catalyst, a kinetic model is proposed. The model is validated with eight new experiments for NH3-SCR and NH3 oxidation. The calculated conversions of NO and NH3 are in good agreement with the experimental values over a wide range of temperatures (150 °C–600 °C), indicating that the model can be used for predicting the catalyst performance of the monolithic Cu-CHA for NH3-SCR.
• In-Exchanged CHA Zeolites for Selective Dehydrogenation of Ethane: Characterization and Effect of Zeolite Framework Type

  Zen Maeno, Xiaopeng Wu, Shunsaku Yasumura, Takashi Toyao, Yasuharu Kanda, Ken-ichi Shimizu

  Catalysts 2020年07月 [査読有り][通常論文]
  
• Frontier Molecular Orbital Based Analysis of Solid-Adsorbate Interactions over Group 13 Metal Oxide Surfaces

  Chong Liu, Yuxin Li, Motoshi Takao, Takashi Toyao, Zen Maeno, Takashi Kamachi, Yoyo Hinuma, Ichigaku Takigawa, Ken-ichi Shimizu

  JOURNAL OF PHYSICAL CHEMISTRY C 124 28 15355 - 15365 2020年07月 

  Adsorption is an essential process that takes place in heterogeneous catalysis. In the current study, solid-adsorbate interactions occurring between a variety of small molecules and surfaces of group beta metal oxides, including beta-Ga2O3(100), beta-Ga2O3(001), theta-Al2O3 (100), theta-Al2O3 (001), theta-Al2O3 (010), In2O3(110), and In2O3(111), were investigated using density functional theory calculations and a machine learning (ML)-based statistical method. The adsorbates utilized for this purpose include CO, CO2, ND NH3, H2O, acetonitrile, acetone, acetamide, acetic acid, alkanes, alkenes, aromatic compounds, alcohols, and amines. The results show that the adsorption energies (E-ads) of each metal oxide surface correlate linearly with the highest occupied molecular orbital (HOMO) energies of the adsorbates and not with energies of the lowest unoccupied molecular orbital (LUMO) of the small molecules. Moreover, in these systems, contributions to molecular adsorption are dominated by interactions between the HOMOs of the adsorbates and the surface conduction band of the metal oxides. Furthermore, the surface energy was found to be an important parameter influencing E-ads values of different metal oxides. Finally, the results of statistical analysis using a ML approach confirmed that adsorbate HOMOs and surface energy of metal oxides are the most influential factors governing molecular adsorption, and also demonstrated that dipole moments of adsorbates contribute to controlling to adsorption.
• Single-atom Pt in intermetallics as an ultrastable and selective catalyst for propane dehydrogenation.

  Yuki Nakaya, Jun Hirayama, Seiji Yamazoe, Ken-Ichi Shimizu, Shinya Furukawa

  Nature communications 11 1 2838 - 2838 2020年06月05日 

  Propylene production via propane dehydrogenation (PDH) requires high reaction temperatures to obtain sufficient propylene yields, which results to prominent catalyst deactivation due to coke formation. Developing highly stable catalysts for PDH without deactivation even at high temperatures is of great interest and benefit for industry. Here, we report that single-atom Pt included in thermally stable intermetallic PtGa works as an ultrastable and selective catalyst for PDH at high temperatures. Intermetallic PtGa displays three-hold-Pt ensembles and single Pt atoms isolated by catalytically inert Ga at the surface, the former of which can be selectively blocked and disabled by Pb deposition. The PtGa-Pb/SiO2 catalyst exhibits 30% conversion with 99.6% propylene selectivity at 600 °C for 96 h without lowering the performance. The single-atom Pt well catalyzes the first and second C-H activation, while effectively inhibits the third one, which minimizes the side reactions to coke and drastically improves the selectivity and stability.
• In Situ Spectroscopic Studies on the Redox Cycle of NH3-SCR over Cu-CHA Zeolites

  Chong Liu, Hiroe Kubota, Takehiro Amada, Kenichi Kon, Takashi Toyao, Zen Maeno, Kakuya Ueda, Junya Ohyama, Atsushi Satsuma, Takuya Tanigawa, Nao Tsunoji, Tsuneji Sano, Ken-ichi Shimizu

  CHEMCATCHEM 12 11 3050 - 3059 2020年06月 

  The selective catalytic reduction of NO with ammonia (NH3-SCR) catalyzed by Cu-CHA zeolites is thoroughly investigated using in situ spectroscopic experiments combined with on-line mass spectroscopy (MS) under steady-state NH3-SCR conditions and transient conditions for Cu(II)/Cu(I) redox cycles. Quantitative analysis of the in situ XANES spectra of Cu-CHA under steady-state conditions of NH3-SCR show that NH3-coordinated Cu(II) species is the dominant Cu species at low temperatures (100-150 degrees C). At higher temperatures, Cu(II) species and [Cu(NH3)(2)](+) complex coexist, possibly because the rate of the Cu(II) -> Cu(I) reduction step is comparable to that of the Cu(I)-> Cu(II) oxidation step. In situ XANES, IR/MS, and UV-vis/MS experiments on the reduction half cycle demonstrate that the reduction of Cu(II) species occurs via the reaction of NH3-liganded Cu(II) with NO to yield N-2 and H2O. For the oxidation half cycle, in situ XANES experiments of Cu(I) oxidation in 10 % O-2 at 200 degrees C indicate that an increased density in CHA zeolite exhibits a higher oxidation rate. In situ UV-vis experiments of Cu(I) reoxidation using different mixtures of oxidant feed gas demonstrate the key role of O-2 in the oxidation cycle. It is suggested that the reoxidation of Cu(I) to Cu(II) species occurs with only O-2 as the oxidant, and a high Cu density in CHA zeolite promotes SCR activity by enhancing the oxidative activation of Cu(I) to Cu(II) during the catalytic cycle.
• Active, Selective, and Durable Catalyst for Alkane Dehydrogenation Based on a Well-Designed Trimetallic Alloy

  Yuki Nakaya, Masayoshi Miyazaki, Seiji Yamazoe, Ken-ichi Shimizu, Shinya Furukawa

  ACS CATALYSIS 10 9 5163 - 5172 2020年05月 

  Catalyst design based on a pseudobinary alloy concept was applied to develop a highly efficient catalytic system for alkane dehydrogenation. A series of Pt-based alloy catalysts supported on silica (Pt3M/SiO2, where M = Fe, Co, Cu, Zn, Ga, In, Sn, Pb) were prepared and tested for the dehydrogenation of methylcyclohexane, which has been an emerging topic in hydrogen carrier/production applications. Nanoparticulate intermetallic Pt3Fe exhibited high catalytic activity and durability. The Pt3Fe catalyst was further modified by substituting a part of the Fe with a series of metals (M = Co, Ni, Cu, Zn, Ga, In, Sn, Pb) to form a Pt-3(Fe-0.75,M-0.25) pseudobinary alloy. The partial substitution of Fe with Zn to form Pt-3(Fe0.75Zn0.25) resulted in outstandingly high catalytic activity, selectivity, and durability: a 2.7-fold higher turnover frequency (TOF) in comparison to that of Pt/SiO2 (the highest H-2 evolution rate ever reported), >99% toluene selectivity (methane concentration <500 ppm), and long-term durability with >99% MCH conversion for at least 50 h. A mechanistic study based on detailed characterization and theoretical calculations revealed that the Fe enhanced hydrogenation of CHx species (decoking) and Zn promoted toluene desorption by both ligand and ensemble effects. The adjacency of Pt, Fe, and Zn in at the atomic level allows construction of a multifunctional active site for effective C-H activation, decoking, and toluene desorption.
• Surface Oxygen Vacancy Formation Energy Calculations in 34 Orientations of beta-Ga2O3 and theta-Al2O3

  Yoyo Hinuma, Takashi Kamachi, Nobutsugu Hamamoto, Motoshi Takao, Takashi Toyao, Ken-ichi Shimizu

  JOURNAL OF PHYSICAL CHEMISTRY C 124 19 10509 - 10522 2020年05月 

  Computational exploration of previously unknown reactive sites is a powerful strategy for the emergence of new catalytic reactions. Exotic surfaces can be theoretically investigated, but there are very few, if any, computational models of high-index orientations that consider the reconstruction of the surface. A workflow to efficiently obtain a set of accessible terminations by removing those that are metastable against macroscopic facet formation and by comparing cleaved surfaces and surfaces suggested by a genetic algorithm (GA) for promising orientations is proposed and demonstrated using 34 orientations of beta-Ga2O3 and theta-Al2O3. Seven and six terminations considered to be experimentally accessible are found for beta-Ga2O3 and theta-Al2O3, respectively, where the highest surface energy was roughly twice that of the lowest. The lowest surface 0 vacancy formation - energies (E-Ovac) among accessible surfaces are 3.04 and 5.46 eV in the (101) and (20 (1) over bar) terminations for beta-Ga2O3 and theta-Al2O3, respectively, where the decreases in E-Ovac, from the most stable surface are 1.32 and 1.11 eV, respectively. The E-Ovac in accessible surfaces showed a good correlation with the descriptors of the local coordination environment, suggesting that exploiting surface O in an unfavorable environment in an accessible termination would enhance O-vacancy-related catalyst performance even in materials that do not show reactivity on the most stable surface.
• Catalytic Methylation of Aromatic Hydrocarbons using CO2/H-2 over Re/TiO2 and H-MOR Catalysts

  Kah Wei Ting, Haruka Kamakura, Sharmin S. Poly, Takashi Toyao, S. M. A. Hakim Siddiki, Zen Maeno, Koichi Matsushita, Ken-ichi Shimizu

  CHEMCATCHEM 12 8 2215 - 2220 2020年04月 

  A combined catalyst comprising TiO2-supported Re (Re(1)/TiO2; Re=1 wt%) and H-MOR (SiO2/Al2O3=90) was found to promote the methylation of benzene using CO2 and H-2. This catalytic system exhibited high performance with regard to the synthesis of methylated benzenes and gave high yields of total methylated products (up to 52 % benzene-based yield and 42 % CO2-based yield) under the reaction conditions employed in this study (p(CO2)=1 MPa; p(H2)=5 MPa; T=250 degrees C; t=20 h) in a batch reactor. Catalyst screening demonstrated that a combination of Re(1)/TiO2 and H-MOR (SiO2/Al2O3=90) exhibited superior performance compared to other combinations of supported metal catalysts and zeolites in terms of both yield and selectivity for methylated benzenes.
• Isolated Indium Hydrides in CHA Zeolites: Speciation and Catalysis for Nonoxidative Dehydrogenation of Ethane.

  Zen Maeno, Shunsaku Yasumura, Xiaopeng Wu, Mengwen Huang, Chong Liu, Takashi Toyao, Ken-Ichi Shimizu

  Journal of the American Chemical Society 142 10 4820 - 4832 2020年03月11日 

  The study of the formation, characterization, and functionality of isolated surface hydrides on solid materials is a formidable task because of the complexity of solid surfaces and the difficulty of analyzing structures in solids. Herein, we found the formation of indium (In) hydride species supported by CHA zeolites. The In hydrides were formed by treatment of an In-exchanged CHA zeolite (In-CHA) with H2 at high temperatures (>773 K). In situ Fourier transform infrared (FTIR) spectroscopy and density functional theory (DFT) calculations revealed that an [InH2]+ ion on a framework anionic site is a plausible structure. In-CHA exhibited high selectivity and durable catalytic activity for the nonoxidative dehydrogenation of ethane for at least 90 h. Kinetic and in situ spectroscopic studies as well as transition state (TS) calculations suggested that [InH2]+ ions serve as catalytically active sites for selective dehydrogenation using In-CHA.
• Coordinated Water as New Binding Sites for the Separation of Light Hydrocarbons in Metal-Organic Frameworks with Open Metal Sites.

  Pia Vervoorts, Andreas Schneemann, Inke Hante, Jenny Pirillo, Yuh Hijikata, Takashi Toyao, Kenichi Kon, Ken-Ichi Shimizu, Takayoshi Nakamura, Shin-Ichiro Noro, Roland A Fischer

  ACS applied materials & interfaces 12 8 9448 - 9456 2020年02月26日 

  Metal-organic frameworks with open metal sites are promising materials for gas separations. Particularly, the M2(dobdc) (dobdc4- = 2,5-dioxidobenzenedicarboxylate, M2+ = Co2+, Mn2+, Fe2+, ...) framework has been the Drosophila of this research field and has delivered groundbreaking results in terms of sorption selectivity. However, many studies focus on perfect two-component mixtures and use theoretical models, e.g., the ideal adsorbed solution theory, to calculate selectivities. Within this work, we shed light on the comparability of these selectivities with values obtained from propane/propene multicomponent measurements on the prototypical Co2(dobdc) framework, and we study the impact of impurities like water on the selectivity. Despite the expected capacity loss, the presence of water does not necessarily lead to a decreased selectivity. Density functional theory calculations of the binding energies prove that the water molecules adsorbed to the metal centers introduce new binding sites for the adsorbates.
• Thermally Induced Transformation of Sb-Containing Trigonal Mo3VOx to Orthorhombic Mo3VOx and Its Effect on the Catalytic Ammoxidation of Propane

  Shoma Inukai, Satoshi Ishikawa, Toyokazu Tanabe, Yuan Jing, Takashi Toyao, Ken-Ichi Shimizu, Wataru Ueda

  Chemistry of Materials 32 4 1506 - 1516 2020年02月25日
• Formation and Reactions of NH4NO3 during Transient and Steady-State NH3-SCR of NOx over H-AFX Zeolites: Spectroscopic and Theoretical Studies

  Hiroe Kubota, Chong Liu, Takashi Toyao, Zen Maeno, Masaru Ogura, Naoto Nakazawa, Satoshi Inagaki, Yoshihiro Kubota, Ken-ichi Shimizu

  ACS Catalysis 10 3 2334 - 2344 2020年02月07日
• Machine Learning for Catalysis Informatics: Recent Applications and Prospects

  Takashi Toyao, Zen Maeno, Satoru Takakusagi, Takashi Kamachi, Ichigaku Takigawa, Ken-ichi Shimizu

  ACS CATALYSIS 10 3 2260 - 2297 2020年02月 

  The discovery and development of catalysts and catalytic processes are essential components to maintaining an ecological balance in the future. Recent revolutions made in data science could have a great impact on traditional catalysis research in both industry and academia and could accelerate the development of catalysts. Machine learning (ML), a subfield of data science, can play a central role in this paradigm shift away from the use of traditional approaches. In this review, we present a user's guide for ML that we believe will be helpful for scientists performing research in the field of catalysis and summarize recent progress that has been made in utilizing ML to create homogeneous and heterogeneous catalysts. The focus of the review is on the design, synthesis, and characterization of catalytic materials/compounds as well as their applications to catalyzed processes. The ML technique not only enhances ways to discover catalysts but also serves as a powerful tool to establish a deeper understanding of relationships between the properties of materials/compounds and their catalytic activities, selectivities, and stabilities. This knowledge facilitates the establishment of principles employed to design catalysts and to enhance their efficiencies. Despite such advantages of ML, it is noteworthly that the current ML-assisted development of real catalysts remains in its infancy, mainly because of the complexity of catalysis associated with the fact that catalysis is a time dependent dynamic event. In this review, we discuss how seamless integration of experiment, theory, and data science can be used to accelerate catalyst development and to guide future studies aimed at applications that will impact society's need to produce energy, materials, and chemicals. Moreover, the limitations and difficulties of ML in catalysis research originating from the complex nature of catalysis are discussed in order to make the catalysis community aware of challenges that need to be addressed for effective and practical use of ML in the field.
• Promotional Effect of La in the Three-Way Catalysis of La-Loaded Al2O3-Supported Pd Catalysts (Pd/La/Al2O3)

  Yuan Jing, Zhengxu Cai, Chong Liu, Takashi Toyao, Zen Maeno, Hiroyuki Asakura, Satoru Hiwasa, Shuhei Nagaoka, Hiroshi Kondoh, Ken-ichi Shimizu

  ACS Catalysis 10 2 1010 - 1023 2020年01月17日
• Mechanistic insights into the oxidation of copper(i) species during NH3-SCR over Cu-CHA zeolites: a DFT study

  Chong Liu, Hiroe Kubota, Takashi Toyao, Zen Maeno, Ken-ichi Shimizu

  Catalysis Science & Technology 10 11 3586 - 3593 2020年
• Machine Learning Predictions of Adsorption Energies of CH4-Related Species

  Takashi Toyao, Ichigaku Takigawa, Ken-ichi Shimizu

  Direct Hydroxylation of Methane 135 - 149 2020年
• In situ/operando spectroscopic studies on NH3–SCR reactions catalyzed by a phosphorus-modified Cu-CHA zeolite

  Hiroe Kubota, Chong Liu, Takehiro Amada, Kenichi Kon, Takashi Toyao, Zen Maeno, Kakuya Ueda, Atsushi Satsuma, Nao Tsunoji, Tsuneji Sano, Kenichi Shimizu

  Catalysis Today 376 73 - 80 2020年 

  The modification of Cu-exchanged zeolites with phosphorus represents a promising method to enhance their hydrothermal stability, which is of pivotal importance for catalysts that promote the selective catalytic reduction of NO with ammonia (NH –SCR). In this study, we investigated the reaction mechanism of NH –SCR catalyzed by a phosphorus-modified CHA zeolite that contains active Cu species (Cu-P-CHA), and assessed the effect of the phosphorus modification on the hydrothermal stability of the catalyst by employing in situ/operando spectroscopic methods. In their entirety, the combined results from in situ/operando IR, UV–vis, and XANES experiments revealed that the NH –SCR process over Cu-P-CHA proceeds via the reduction of Cu(II) to Cu(I) followed by a reoxidation of Cu(I) to Cu(II). In addition, we found that the phosphorus modification improved the hydrothermal durability of the catalyst by retaining a higher amount of the redox-active Cu species and the zeolite framework. 3 3 3
• Highly active and noble-metal-alternative hydrogenation catalysts prepared by dealloying Ni-Si intermetallic compounds.

  Wiyanti F Simanullang, Hiroshi Itahara, Naoko Takahashi, Satoru Kosaka, Ken-Ichi Shimizu, Shinya Furukawa

  Chemical communications (Cambridge, England) 55 93 13999 - 14002 2019年12月04日 

  Noble-metal-alternative Ni-Si catalysts more active than Pd in the hydrogen storage reaction were developed using a unique procedure, i.e., surface dealloying with hydrofluoric acid treatment. The combination of the structural analysis and the DFT calculation revealed a specific active site structure, a Ni cluster embedded in a SiO2 matrix, and its unprecedented role in the molecular conversion.
• Acetalization of glycerol with ketones and aldehydes catalyzed by high silica H beta zeolite

  Sharmin Sultana Poly, Md A. R. Jamil, Abeda S. Touchy, Shunsaku Yasumura, S. M. A. Hakim Siddiki, Takashi Toyao, Zen Maeno, Ken-ichi Shimizu

  MOLECULAR CATALYSIS 479 176 - 181 2019年12月 

  In this work, proton-exchanged *BEA zeolite with a high Si/Al ratio of 75 (H beta-75), was demonstrated as an effective catalyst for the acetalization of glycerol with carbonyl compounds. This catalyst system was applicable to various substrates and reusable for at least 4 times with slight decrease in activity. The turnover frequency, based on acid site concentration, increased as a function of H beta Si/Al ratio, indicating the importance of the zeolite hydrophobic surface properties. The origin of the high efficiency exhibited by H beta-75 is quantitatively discussed based on kinetic studies, hydrophobicity, and acid site concentration.
• Mechanistic study of the selective hydrogenation of carboxylic acid derivatives over supported rhenium catalysts Electronic supplementary information (ESI) available. See DOI: 10.1039/c9cy01404g

  Takashi Toyao, Kah Wei Ting, S. M. A. Hakim Siddiki, Abeda S. Touchy, Wataru Onodera, Zen Maeno, Hiroko Ariga-Miwa, Yasuharu Kanda, Kiyotaka Asakura, Ken-ichi Shimizu

  CATALYSIS SCIENCE & TECHNOLOGY 9 19 5413 - 5424 2019年10月 

  The structure and performance of TiO2-supported Re (Re/TiO2) catalysts for selective hydrogenation of carboxylic acid derivatives have been investigated. Re/TiO2 promotes selective hydrogenation reactions of carboxylic acids and esters that form the corresponding alcohols, and of amides that generate the corresponding amines. These processes are not accompanied by reduction of aromatic moieties. A Re loading amount of 5 wt% and a catalyst pretreatment with H-2 at 500 degrees C were identified as being optimal to obtain the highest catalytic activity for the hydrogenation processes. The results of studies using various characterization methods, including X-ray diffraction (XRD), X-ray absorption fine structure (XAFS), X-ray photoelectron spectroscopy (XPS), and scanning transmission electron microscopy (STEM), indicate that the Re species responsible for the catalytic hydrogenation processes have sub-nanometer to a few nanometer sizes and average oxidation states higher than 0 and below +4. The presence of either a carboxylic acid and/or its corresponding alcohol is critical for preventing the Re/TiO2 catalyst from promoting production of dearomatized byproducts. Although Re/TiO2 is intrinsically capable of hydrogenating aromatic rings, carboxylic acids, alcohols, amides, and amines strongly adsorb on the Re species, which leads to suppression of this process. Moreover, the developed catalytic system was applied to selective hydrogenation of triglycerides that form the corresponding alcohols.
• Bulk Vanadium Oxide versus Conventional V2O5/TiO2: NH3-SCR Catalysts Working at a Low Temperature Below 150 degrees C

  Yusuke Inomata, Shinichi Hata, Makoto Mino, Eiji Kiyonaga, Keiichiro Morita, Kenji Hikino, Kazuhiro Yoshida, Hiroe Kubota, Takashi Toyao, Ken-ichi Shimizu, Masatake Haruta, Toru Murayama

  ACS CATALYSIS 9 10 9327 - 9331 2019年10月 [査読有り][通常論文]
   

  Practical catalysts that work at a low temperature for selective catalytic reduction of NOx using NH3 (NH3-SCR) have been required to treat NOx at the outlet temperature in boiler systems (100-150 degrees C). In this paper, we report bulk vanadium oxide catalysts that show NH3-SCR activity at a low temperature below 150 degrees C. Defective bulk vanadium oxide (V(V)+V(IV)) catalysts were synthesized by the calcination of vanadium(IV)-oxalate at 270 degrees C (1-4 h). The reaction rate per mol of surface vanadium atom of the catalyst calcined at 270 degrees C for 2 h (V 270-2, 6.4 x 10(-2) mol(NO) molV(-1) s(-1)) was 10-14 times faster than those of conventional 1-9 wt % V2O5/TiO2 (4.5 x 10(-3)-6.1 x 10-3 mol(NO) mol(V)(-1) s(-1)), indicating that bulk vanadium oxide is more favorable for NH3-SCR and V(IV) species enhance the activity. The NH3-SCR of V 270-2 is driven by the Lewis acid mechanism, which proceeds faster than the Bronsted acid mechanism.
• A Cu-Pd single-atom alloy catalyst for highly efficient NO reduction.

  Feilong Xing, Jaewan Jeon, Takashi Toyao, Ken-Ichi Shimizu, Shinya Furukawa

  Chemical science 10 36 8292 - 8298 2019年09月28日 [査読有り][通常論文]
   

  A series of Cu-Pd alloy nanoparticles supported on Al2O3 were prepared and tested as catalysts for deNO x reactions. XRD, HAADF-STEM, XAFS, and FT-IR analyses revealed that a single-atom alloy structure was formed when the Cu/Pd ratio was 5, where Pd atoms were well isolated by Cu atoms. Compared with Pd/Al2O3, Cu5Pd/Al2O3 exhibited outstanding catalytic activity and N2 selectivity in the reduction of NO by CO: for the first time, the complete conversion of NO to N2 was achieved even at 175 °C, with long-term stability for at least 30 h. High catalytic performance was also obtained in the presence of O2 and C3H6 (model exhaust gas), where a 90% decrease in Pd use was achieved with minimum evolution of N2O. Kinetic and DFT studies demonstrated that N-O bond breaking of the (NO)2 dimer was the rate-determining step and was kinetically promoted by the isolated Pd.
• Statistical Analysis and Discovery of Heterogeneous Catalysts Based on Machine Learning from Diverse Published Data

  Suzuki Keisuke, Toyao Takashi, Maeno Zen, Takakusagi Satoru, Shimizu Ken-ichi, Takigawa Ichigaku

  CHEMCATCHEM 11 18 4537 - 4547 2019年09月19日 [査読有り][通常論文]
   

  The literature provides insights for catalyst design and discovery. Effective analysis of reported data using machine learning (ML) methods offers the ability to gain valuable information. However, utilizing the literature in this way has obstacles such as lack of compositional overlaps, bias from prior published data, and low sample counts for many elements. The present study describes an ML approach that considers elemental features as input representations instead of inputting catalyst compositions directly. This ML method has the potential for catalyst discovery, including catalytic reactions with limited catalyst composition overlap in the available data. Oxidative coupling of methane (OCM), water gas shift (WGS), and CO oxidation reactions were chosen to confirm the effectiveness of the proposed method by analysis using several state-of-the-art ML methods. Among the ML methods tested, gradient boosting regression with XGBoost (XGB) provided the best results, and prediction accuracy was improved by the proposed approach for all three reaction types. In addition, a quantitative value of "feature importance score" was calculated to evaluate the most influential input variables on catalyst performance. Finally, catalyst optimization was explored using ML as a "surrogate" model, and the top 20 promising candidate catalysts were identified for the OCM reaction based on the optimization. The advantages of ML in catalysis analysis as well as the difficulties and limitations originating from the complexity of heterogeneous catalysis were explored.
• Statistical Analysis and Discovery of Heterogeneous Catalysts Based on Machine Learning from Diverse Published Data

  Suzuki Keisuke, Toyao Takashi, Maeno Zen, Takakusagi Satoru, Shimizu Ken-ichi, Takigawa Ichigaku

  CHEMCATCHEM 11 18 4443 - 4443 2019年09月12日 [査読有り][通常論文]
   

  The front cover artwork for Issue 18/2019 is provided by the groups Ken-ichi Shimizu group at Hokkaido University (Japan) and Ichigaku Takigawa at RIKEN (Japan). The image shows future catalysis research using artificial intelligence (AI). See the Full Paper itself at https://doi.org/10.1002/cctc.201900971.
• Heterogeneous Pt and MoOx Co-Loaded TiO2 Catalysts for Low-Temperature CO2 Hydrogenation To Form CH3OH

  Takashi Toyao, Shingo Kayamori, Zen Maeno, S. M. A. Hakim Siddiki, Ken-ichi Shimizu

  ACS CATALYSIS 9 9 8187 - 8196 2019年09月 [査読有り][通常論文]
   

  Efficient conversion of CO2 into useful chemicals, exemplified by the development of methods for low-temperature hydrogenation of CO2 to form methanol (CH3OH), is a highly attractive research target. Herein, we report that Pt nanoparticles, loaded on MoOx/TiO2 as a support (Pt(3)/MoOx(30)TiO2; Pt 3 wt %, MoO3 30 wt %), promote selective hydrogenation of CO2 to produce CH3OH in 73% yield under mild conditions (T = 150 degrees C; t = 48 h; P-CO2 = 1 MPa; P-H2 = 5 MPa). It is significant that the observed yield is almost the equilibrium yield of CH3OH expected under the current reaction conditions. In terms of both the yield and selectivity for CH3OH production, the performance of Pt(3)/MoOx(30)/TiO2 is better than that of other metal catalysts supported on MoOx (30)/TiO2 and of Pt catalysts on other supports. Moreover, the results of an investigation of the reaction mechanism using in situ X-ray absorption fine structure (XAFS) suggest that reduced MoOx species are responsible for the progress of this efficient reaction.
• Front Cover: Direct Phenolysis Reactions of Unactivated Amides into Phenolic Esters Promoted by a Heterogeneous CeO2 Catalyst (Chem. Eur. J. 45/2019)

  Md. Nurnobi Rashed, S. M. A. Hakim Siddiki, Abeda Sultana Touchy, Md. A. R. Jamil, Sharmin Sultana Poly, Takashi Toyao, Zen Maeno, Ken‐ichi Shimizu

  Chemistry – A European Journal 2019年08月09日
• Direct Phenolysis Reactions of Unactivated Amides into Phenolic Esters Promoted by a Heterogeneous CeO2 Catalyst.

  Md Nurnobi Rashed, S M A Hakim Siddiki, Abeda Sultana Touchy, Md A R Jamil, Sharmin Sultana Poly, Takashi Toyao, Zen Maeno, Ken-Ichi Shimizu

  Chemistry (Weinheim an der Bergstrasse, Germany) 25 45 10594 - 10605 2019年08月09日 [査読有り][通常論文]
   

  The direct catalytic esterification of amides that leads to the construction of C-O bonds through the cleavage of amide C-N bonds is a highly attractive strategy in organic synthesis. While aliphatic and aromatic alcohols can be readily used for the alcoholysis of activated and unactivated amides, the introduction of phenols is more challenging due to their lower nucleophilicity in the phenolysis of unactivated amides. Herein, we demonstrate that phenols can be used for the phenolysis of unactivated amides into the corresponding phenolic esters using a simple heterogenous catalytic system based on CeO2 under additive-free reaction conditions. The method tolerates a broad variety of functional groups (>50 examples) in the substrates. Results of kinetic studies afforded mechanistic insights into the principles governing this reaction, suggesting that the cooperative effects of the acid-base functions of catalysts would be of paramount importance for the efficient progression of the C-N bond breaking process, and consequently, CeO2 showed the best catalytic performance among the catalysts explored.
• Linear Correlations between Adsorption Energies and HOMO Levels for the Adsorption of Small Molecules on TiO2 Surfaces

  Takashi Kamachi, Toshinobu Tatsumi, Takashi Toyao, Yoyo Hinuma, Zen Maeno, Satoru Takakusagi, Shinya Furukawa, Ichigaku Takigawa, Ken-ichi Shimizu

  JOURNAL OF PHYSICAL CHEMISTRY C 123 34 20988 - 20997 2019年08月 [査読有り][通常論文]
   

  Adsorption is a fundamental step in catalysis on a solid surface, and therefore, its understanding is important for explaining its behavior. This work investigated the adsorption of various small molecules, including H-2, N-2, CO, CO2, CH4, NH3, H2O, H2S, dimethyl sulfoxide, alkanes, alkenes, alkynes, aromatic compounds, alcohols, aldehydes, ketones, nitriles, carboxylic acids, amides, and amines, on the anatase (101) and rutile (110) surfaces of TiO2, using periodic density functional theory calculations and statistical methods. Adsorption energies were computed at the same level of theory to obtain a clean and consistent data set. A linear relationship was observed between the adsorption energies of these molecules and their highest occupied molecular orbital (HOMO) levels, whereas no obvious correlation was evident for the lowest unoccupied molecular orbital levels. Improved correlations between the adsorption energies and HOMO levels were generated by dividing these, molecules into two subgroups: hydrocarbons and heteroatom- containing compounds. Interactions between frontier molecular orbitals and the surfaces were considered, to gain a better understanding of the significant correlations that were identified. The data show that these relationships can be primarily ascribed to the interactions between the HOMO of the small molecule and conduction state of the TiO2 surface. The statistical analysis using machine learning demonstrated that the HOMO and dipole moment are the first and second most important properties, respectively, in terms of rationalizing and predicting the adsorption energies.
• Micropore diffusivities of NO and NH3 in Cu-ZSM-5 and their effect on NH3-SCR

  Nakasaka Yuta, Kanda Takumi, Shimizu Ken-ichi, Kon Kenichi, Shibata Gen, Masuda Takao

  CATALYSIS TODAY 332 64 - 68 2019年07月15日 [査読有り][通常論文]
  
• NH3-SCR by monolithic Cu-ZSM-5 and Cu-AFX catalysts: Kinetic modeling and engine bench tests

  Shibata Gen, Eijima Wataru, Koiwai Ryutaro, Shimizu Ken-ichi, Nakasaka Yuta, Kobashi Yoshimitsu, Kubota Yoshihiro, Ogura Masaru, Kusaka Jin

  CATALYSIS TODAY 332 59 - 63 2019年07月15日 [査読有り][通常論文]
  
• Cover Feature: Selective Transformations of Triglycerides into Fatty Amines, Amides, and Nitriles by using Heterogeneous Catalysis (ChemSusChem 13/2019)

  Md. A. R. Jamil, S. M. A. Hakim Siddiki, Abeda Sultana Touchy, Md. Nurnobi Rashed, Sharmin Sultana Poly, Yuan Jing, Kah Wei Ting, Takashi Toyao, Zen Maeno, Ken‐ichi Shimizu

  ChemSusChem 12 13 2831 - 2831 2019年07月05日
• Selective Transformations of Triglycerides into Fatty Amines, Amides, and Nitriles by using Heterogeneous Catalysis.

  Md A R Jamil, S M A Hakim Siddiki, Abeda Sultana Touchy, Md Nurnobi Rashed, Sharmin Sultana Poly, Yuan Jing, Kah Wei Ting, Takashi Toyao, Zen Maeno, Ken-Ichi Shimizu

  ChemSusChem 12 13 3115 - 3125 2019年07月05日 [査読有り][通常論文]
   

  The use of triglycerides as an important class of biomass is an effective strategy to realize a more sustainable society. Herein, three heterogeneous catalytic methods are reported for the selective one-pot transformation of triglycerides into value-added chemicals: i) the reductive amination of triglycerides into fatty amines with aqueous NH3 under H2 promoted by ZrO2 -supported Pt clusters; ii) the amidation of triglycerides under gaseous NH3 catalyzed by high-silica H-beta (Hβ) zeolite at 180 °C; iii) the Hβ-promoted synthesis of nitriles from triglycerides and gaseous NH3 at 220 °C. These methods are widely applicable to the transformation of various triglycerides (C4 -C18 skeletons) into the corresponding amines, amides, and nitriles.
• Experimental and theoretical study of multinuclear indium-oxo clusters in CHA zeolite for CH4 activation at room temperature.

  Zen Maeno, Shunsaku Yasumura, Chong Liu, Takashi Toyao, Kenichi Kon, Akira Nakayama, Jun-Ya Hasegawa, Ken-Ichi Shimizu

  Physical chemistry chemical physics : PCCP 21 25 13415 - 13427 2019年06月26日 [査読有り][通常論文]
   

  We have carried out an experimental and theoretical study of CHA-zeolite supported indium (In)-oxo clusters that promote CH4 activation at room temperature. X-ray absorption fine structure (XAFS) measurements indicate the formation of multinuclear In-oxo clusters by the O2 activation of the In(i)-exchanged CHA zeolite prepared through reductive solid-state ion exchange (RSSIE). The structure of the In-oxo clusters and their locations were investigated in detail using ab initio thermodynamic analysis. The redox properties of the In species during RSSIE and the formation of the In-oxo clusters were also studied by temperature programmed reaction and in situ XAFS measurements. The reaction of CH4 on the O2-activated In-CHA zeolite was monitored using IR spectroscopy where adsorbed formic acid was generated at room temperature. The adsorption and C-H activation of CH4 on our plausible model of the In-oxo clusters were theoretically investigated using density functional theory calculations. We found that CH4 is likely to adsorb and react more easily on dinuclear In-oxo ions than on monomeric In-oxo ions and that the C-H bond cleavage reaction occurs via a heterolytic pathway rather than a homolytic pathway. This study reveals the potential of multinuclear In-oxo clusters as active sites for the transformation of CH4 to oxygenates under mild reaction conditions.
• Heterogeneous Additive-Free Hydroboration of Alkenes Using Cu-Ni/Al2O3: Concerted Catalysis Assisted by Acid- Base Properties and Alloying Effects

  Furukawa Shinya, Ieda Mayuko, Shimizu Ken-ichi

  ACS CATALYSIS 9 6 5096 - 5103 2019年06月 [査読有り][通常論文]
   

  This study describes our development of a Cu-based heterogeneous catalytic system for additive-free hydroboration of alkenes. Surveying monometallic Cu supported on various oxides revealed that Al2O3 provided the best catalytic support with respect to this reaction. A typical volcano-type relationship between the TOF and isoelectric point of the support was observed, which suggests that both acidic and basic properties were necessary to promote this reaction. The catalytic activity of Cu/Al2O3 was further enhanced by the addition of Ni, whereas the selectivity decreased as Ni content increased. The combination of X-ray diffraction, high-angle annular dark-field scanning transmission electron microscopy energy-dispersive system, and extended X-ray absorption fine structure analyses demonstrated the homogeneous formation of a Cu-Ni solid-solution alloy on Al2O3. The optimized Cu5Ni/Al2O3 catalyst exhibited high catalytic performance for styrene hydroboration (98% yield at 25 degrees C for 6 h). A mechanistic study revealed that (1) ethanol adsorbed on a Lewis acid site of Al2O3 released a proton to the alkene, generating a carbocation intermediate, (2) diboron was activated by a basic site in the Al2O3 structure, which was followed by a nucleophilic attack on the carbocation to form the final product, and (3) Ni acted as an efficient adsorption site for alkene, which facilitated the protonation of alkene as the rate-determining step. The catalysis was assisted by acid-base properties and an alloying effect, which resulted in a unique reaction mechanism and an efficient catalytic system for hydroboration.
• Catalytic Activity of Rhodium Phosphide for Selective Hydrodeoxygenation of Phenol

  Kanda Yasuharu, Chiba Taiyo, Aranai Ryusei, Yasuzawa Toshiya, Ueno Ren, Toyao Takashi, Kato Kazuo, Obora Yasushi, Shimizu Ken-ichi, Uemichi Yoshio

  CHEMISTRY LETTERS 48 5 471 - 474 2019年05月 [査読有り][通常論文]
  
• Design of Pd-based pseudo-binary alloy catalysts for highly active and selective NO reduction.

  Jaewan Jeon, Ken-Ichi Kon, Takashi Toyao, Ken-Ichi Shimizu, Shinya Furukawa

  Chemical science 10 15 4148 - 4162 2019年04月21日 [査読有り][通常論文]
   

  The development of Pd-based alloy catalysts for highly active and selective reduction of NO by CO was investigated. A survey of Pd-based bimetallic catalysts (PdM/Al2O3: M = Cu, In, Pb, Sn, and Zn) revealed that the PdIn/Al2O3 catalyst displayed excellent N2 selectivity even at low temperatures (100% at 200 °C). The catalytic activity of PdIn was further improved by substituting a part of In with Cu, where a Pd(In1-x Cu x ) pseudo-binary alloy structure was formed. The optimized catalyst, namely, Pd(In0.33Cu0.67)/Al2O3, facilitated the complete conversion of NO to N2 (100% yield) even at 200 °C and higher, which has never been achieved using metallic catalysts. The formation of the pseudo-binary alloy structure was confirmed by the combination of HAADF-STEM-EDS, EXAFS, and CO-FT-IR analyses. A detailed mechanistic study based on kinetic analysis, operando XAFS, and DFT calculations revealed the roles of In and Cu in the significant enhancement of catalytic performance: (1) N2O adsorption and decomposition (N2O → N2 + O) were drastically enhanced by In, thus resulting in high N2 selectivity; (2) CO oxidation was promoted by In, thus leading to enhanced low-temperature activity; and (3) Cu substitution improved NO adsorption and dissociation (NO → N + O), thus resulting in the promotion of high-temperature activity.
• Low-Temperature Hydrogenation of CO2 to Methanol over Heterogeneous TiO2-Supported Re Catalysts

  Kah Wei Ting, Takashi Toyao, S. M. A. Hakim Siddiki, Ken-ichi Shimizu

  ACS CATALYSIS 9 4 3685 - 3693 2019年04月 [査読有り][通常論文]
   

  Hydrogenation of carbon dioxide (CO2) to methanol (MeOH) is an effective strategy for CO2 utilization. Because of a low equilibrium conversion of CO2 to MeOH at high temperature, development of efficient catalytic CO2 hydrogenation processes that operate under low reaction temperature is of extreme importance. Herein, we report that TiO2 -supported Re (Re(1)/TiO2 ; Re = 1 wt %) promotes the selective hydrogenation of CO2 to MeOH (total TON based on Re = 44, MeOH selectivity = 82%) under mild conditions (p(CO2)= 1 MPa; P-H2 = 5 MPa; T = 150 degrees C). Both in terms of TON and methanol selectivity, the performance of Re(1)/TiO2 is superior to that of TiO2 catalysts loaded with other metals and to Re catalysts on other support materials. In addition, our investigations include the reaction mechanism and structure-activity relationship for the catalytic system used in this study, suggesting that relatively reduced Re species (oxidation state: 0-4) of subnanometer size serve as the catalytically active site for the formation of MeOH.
• アンモニアSCR用Cu-ZSM-5触媒の定常反応モデルの構築

  永島渉, 小祝隆太郎, 柴田元, 小橋好充, 小川英之, 清水研一, 草鹿仁

  自動車技術会論文集 50 2 323 - 327 2019年03月 [査読有り][通常論文]
  
• N-Methylation of amines and nitroarenes with methanol using heterogeneous platinum catalysts

  Jamil Md. A. R, Touchy Abeda S, Rashed Md. Nurnobi, Ting Kah Wei, Siddiki S, M. A. Hakim, Toyao Takashi, Maeno Zen, Shimizu Ken-ichi

  JOURNAL OF CATALYSIS 371 47 - 56 2019年03月 [査読有り][通常論文]
  
• Combined Automated Reaction Pathway Searches and Sparse Modeling Analysis for Catalytic Properties of Lowest Energy Twins of Cu13.

  Takeshi Iwasa, Takaaki Sato, Makito Takagi, Min Gao, Andrey Lyalin, Masato Kobayashi, Ken-Ichi Shimizu, Satoshi Maeda, Tetsuya Taketsugu

  The journal of physical chemistry. A 123 1 210 - 217 2019年01月10日 [査読有り][通常論文]
   

  In nanocatalysis, growing attention has recently been given to investigation of energetically low-lying structural isomers of atomic clusters, because some isomers can demonstrate better catalytic activity than the most stable structures. In this study, we present a comparative investigation of catalytic activity for NO dissociation of a pair of the energetically degenerated isomers of Cu13 cluster having C2 and C s symmetries. It is shown that although these isomers have similar structural, electronic, and optical properties, they can possess very different catalytic activities. The effect of isomerization between cluster isomers is considered using state-of-the-art automated reaction pathway search techniques such as an artificial force induced reaction (AFIR) method as a part of a global reaction route mapping (GRRM) strategy. This method allows effectively to locate a large number of possible reaction pathways and transition states (TSs). In total, 12 TSs for NO dissociation were obtained for Cu13, of C2, C s, as well as I h isomers. Sparse modeling analysis shows that LUMO is strongly negatively correlated with total energy of TSs. For most TSs, LUMO has the antibonding character of NO, consisting of the interaction between π* of NO and SOMO of Cu13. Therefore, an increase in the strength of interaction between NO molecule and Cu13 cluster causes the rise in energy of the LUMO, resulting in lowering of the TS energy for NO dissociation. The combination of the automated reaction pathway search technique and sparse modeling represents a powerful tool for analysis and prediction of the physicochemical properties of atomic clusters, especially in the regime of structural fluxionality, where traditional methods based on random geometry search analyses are difficult.
• Lewis Acid Catalysis of Nb2O5 for Reactions of Carboxylic Acid Derivatives in the Presence of Basic Inhibitors

  Siddiki S, M, A. Hakim, Rashed Md. Nurnobi, Ali Md. Ayub, Toyao Takashi, Hirunsit Pussana, Ehara Masahiro, Shimizu Ken-ichi

  CHEMCATCHEM 11 1 383 - 396 2019年01月09日 [査読有り][通常論文]
  
• 4価バナジウムを含んだバルク酸化バナジウム触媒の低温(150^oC以下)におけるNH₃-SCR活性

  猪股 雄介, 清永 英嗣, 盛田 啓一郎, 吉田 和広, 窪田 博愛, 鳥屋尾 隆, 清水 研一, 春田 正毅, 村山 徹

  石油学会 年会・秋季大会講演要旨集 2019 0 175 - 175 公益社団法人 石油学会 2019年 [査読有り][通常論文]
   

  150^oC以下での低温脱硝を目指し、バルク酸化バナジウムをベースとしたNH₃-SCR触媒を検討した。前駆体にバナジウムシュウ酸錯体を用い、焼成温度を270^oC、焼成時間を1-4hとすることで4価および5価バナジウム成分が共存した酸化バナジウム触媒を合成した。この触媒のNH₃-SCR活性を測定したところ、酸化チタン担持酸化バナジウム触媒および5価バナジウムのみからなるV₂O₅触媒と比較し、NO転化率および反応速度の増大が確認された。4価バナジウム成分が存在することによる活性化エネルギーの低下に起因することが示唆された。

• Kinetic Modeling of Ammonia-SCR and Experimental Studies over Monolithic Cu-ZSM-5 Catalyst

  Wataru Eijima, Gen Shibata, Yoshimitsu Kobashi, Ryutaro Koiwai, Hideyuki Ogawa, Kenichi Shimizu, Jin Kusaka

  SAE Technical Paper 2019-01-0024 2019年01月 [査読有り][通常論文]
  
• Esterification of Tertiary Amides by Alcohols Through C-N Bond Cleavage over CeO2

  Takashi Toyao, Md Nurnobi Rashed, Yoshitsugu Morita, Takashi Kamachi, S. M. A. Hakim Siddiki, Md A. Ali, A. S. Touchy, Kenichi Kon, Zen Maeno, Kazunari Yoshizawa, Ken-ichi Shimizu

  CHEMCATCHEM 11 1 449 - 456 2019年01月 [査読有り][通常論文]
   

  CeO2 has been found to promote ester forming alcoholysis reactions of tertiary amides. The present catalytic system is operationally simple, recyclable, and it does not require additives. The esterification process displays a wide substrate scope (>45 examples; up to 93% isolated yield). Results of a density functional theory (DFT) study combined with insitu FT-IR observations indicate that the process proceeds through rate limiting addition of a CeO2 lattice oxygen to the carbonyl group of the adsorbed acetamide species with energy barrier of 17.0kcal/mol. This value matches well with experimental value (17.9kcal/mol) obtained from analysis of the Arrhenius plot. Further studies by insitu FT-IR and temperature programmed desorption using probe molecules demonstrate that both acidic and basic properties are important, and consequently, CeO2 showed the best performance for the C-N bond cleavage reaction.
• Extraordinarily large kinetic isotope effect on alkene hydrogenation over Rh-based intermetallic compounds.

  Shinya Furukawa, Pingping Yi, Yuji Kunisada, Ken-Ichi Shimizu

  Science and technology of advanced materials 20 1 805 - 812 2019年 [査読有り][通常論文]
   

  A series of Rh-based intermetallic compounds supported on silica was prepared and tested in alkene hydrogenation at room temperature. H2 and D2 were used as the hydrogen sources and the kinetic isotope effect (KIE) in hydrogenation was studied. In styrene hydrogenation, the KIE values differed strongly depending on the intermetallic phase, and some intermetallic compounds with Sb and Pb exhibited remarkably high KIE values (>28). An extraordinarily high KIE value of 91, which has never been reported in catalytic reactions at room temperature, was observed particularly for RhPb2/SiO2. RhPb2/SiO2 also showed high KIE values in the hydrogenation of other unsaturated hydrocarbons such as phenylacetylene and cyclohexene. The density functional theory calculation focused on the surface diffusion of hydrogen suggested no contribution of the quantum tunneling effect to the high KIE values observed. A kinetic study revealed that the dissociative adsorption of H2 (D2) was the rate-determining step in the styrene hydrogenation over RhPb2/SiO2. We propose that the large KIE originates from the quantum tunneling occurring at the hydrogen adsorption process with the aid of the specific surface structure of the intermetallic compound and adsorbate alkene.
• High-silica H beta zeolites for catalytic hydration of hydrophobic epoxides and alkynes in water

  Poly Sharmin Sultana, Siddiki S, M. A. Hakim, Touchy Abeda S, Yasumura Shunsaku, Toyao Takashi, Maeno Zen, Shimizu Ken-ichi

  JOURNAL OF CATALYSIS 368 145 - 154 2018年12月 [査読有り][通常論文]
   

  We investigated the hydration of hydrophobic epoxides and alkynes in water using 24 types of heterogeneous and homogeneous catalysts and found that Hbeta (H beta) zeolite with a relatively high Si/Al ratio (Si/Al = 75), H beta-75, is an effective catalyst. H beta-75 showed wide substrate scope, good reusability, and applicability in gram-scale synthesis for both types of reactions. The effects of hydrophobicity, acidity, and the size of zeolite pores were also comprehensively studied through the hydration of hydrophilic and hydrophobic epoxides and alkynes with different molecular sizes using two types of zeolite (H beta and HZSM5). The high yields obtained using the H beta-75 catalyst in the hydration of hydrophobic epoxides and alkynes are attributed to the hydrophobic interaction between zeolite pores with the substrates, as well as the relatively large pore size. (C) 2018 Elsevier Inc. All rights reserved.
• Acceptorless Dehydrogenative Synthesis of Pyrimidines from Alcohols and Amidines Catalyzed by Supported Platinum Nanoparticles

  Poly Sharmin Sultana, Siddiki S, M. A. Hakim, Touchy Abeda S, Ting Kah Wei, Toyao Takashi, Maeno Zen, Kanda Yasuharu, Shimizu Ken-ichi

  ACS CATALYSIS 8 12 11330 - 11341 2018年12月 [査読有り][通常論文]
   

  A one-pot, acceptorless dehydrogenative method, using a carbon-supported Pt catalyst (Pt/C) along with KOtBu, has been developed for the synthesis of 2,4,6-trisubstituted pyrimidines from secondary and primary alcohols, and amidines. The reaction takes place efficiently using a wide range of substrate scopes (32 examples with isolated yields up to 92%). The Pt/C catalyst that promotes this process is reusable and has a higher turnover number (TON) than those employed in previously reported methods. The results of mechanistic studies suggest that the process takes place through a pathway that begins with Pt-catalyzed acceptorless dehydrogenation of the alcohol substrate, which is followed by sequential condensation, cyclization, and dehydrogenation. Measurements of the turnover frequency combined with the results of density functional theory calculations on different metal surfaces suggest that the adsorption energy of H on the Pt surface is optimal for the acceptorless dehydrogenation process, which cause the higher catalytic activity of Pt over those of other metals.
• Density Functional Theory Calculations of Oxygen Vacancy Formation and Subsequent Molecular Adsorption on Oxide Surfaces

  Yoyo Hinuma, Takashi Toyao, Takashi Kamachi, Zen Maeno, Satoru Takakusagi, Shinya Furukawa, Ichigaku Takigawa, Ken-ichi Shimizu

  JOURNAL OF PHYSICAL CHEMISTRY C 122 51 29435 - 29444 2018年12月 [査読有り][通常論文]
   

  The surface oxygen vacancy formation energy (E-Ovac) is an important parameter in determining the catalytic activity of metal oxides. Estimating these energies can therefore lead to data-driven design of promising catalyst candidates. In the present study, we determine E-Ovac for various insulating and semiconducting oxides. Statistical investigations indicate that the band gap, bulk formation energy, and electron affinity are factors that strongly influence E-Ovac. Electrons enter defect states after O desorption, and these states can be in the valence band, mid-gap, or in the conduction band. Subsequent adsorption of O-2, NO, CO,CO2, and H-2 molecules on an O-deficient surface is also investigated. These molecules become preferentially adsorbed at the defect sites, and E-Ovac is identified as the dominant factor that determines the adsorption mode as well as a descriptor that shows good correlation with the adsorption energy.
• Origin of Nb2O5 Lewis Acid Catalysis for Activation of Carboxylic Acids in the Presence of a Hard Base

  Pussana Hirunsit, Takashi Toyao, S. M. A. Hakim Siddiki, Kenichi Shimizu, Masahiro Ehara

  ChemPhysChem 19 21 2848  2018年11月05日 [査読有り][通常論文]
  
• Front Cover: Origin of Nb2 O5 Lewis Acid Catalysis for Activation of Carboxylic Acids in the Presence of a Hard Base (ChemPhysChem 21/2018)

  Pussana Hirunsit, Takashi Toyao, S. M, A, Hakim Siddiki, Kenichi Shimizu, Masahiro Ehara

  ChemPhysChem 19 21 2804  Wiley 2018年11月 [査読有り][通常論文]
  
• The Catalytic Reduction of Carboxylic Acid Derivatives and CO2 by Metal Nanoparticles on Lewis-Acidic Supports.

  Takashi Toyao, S M A Hakim Siddiki, Kenichi Kon, Ken-Ichi Shimizu

  Chemical record (New York, N.Y.) 18 10 1374 - 1393 2018年10月 [査読有り][通常論文]
   

  The development of heterogeneous catalysts for green chemical synthesis is currently a growing area in catalysis and sustainable chemistry. Especially the use of renewable carbon resources such as carbon dioxide (CO2 ) and biomass-derived compounds (e. g. carboxylic acids, esters, and amides) represent highly attractive research targets. As these substances reside in a high oxidation state, efficient reduction processes are required in order to convert these substrates into useful and value-added chemicals. Moreover, in the interest of mass production, these substrates should be reduced by molecular H2 and a heterogeneous catalyst. In this context, our group has developed advanced catalysts and established design guidelines for catalysts that promote the reductive transformations of carboxylic acid derivatives and CO2 . Our studies show that cooperative catalysis between Lewis-acidic sites on the catalyst support and supported metal nanoparticles are crucial for the success of these challenging hydrogenations. In this review, we summarize the results of our recent studies on the direct synthesis of value-added chemicals from CO2 and carboxylic acid derivatives using supported transition-metal catalysts, and we propose a design concept for heterogeneous catalysts that promote these processes.
• Design of Interfacial Sites between Cu and Amorphous ZrO2 Dedicated to CO2-to-Methanol Hydrogenation

  Tada Shohei, Kayamori Shingo, Honma Tetsuo, Kamei Hiromu, Nariyuki Akane, Kon Kenichi, Toyao Takashi, Shimizu Ken-ichi, Satokawa Shigeo

  ACS CATALYSIS 8 9 7809 - 7819 2018年09月 [査読有り][通常論文]
   

  © 2018 American Chemical Society. We examined the formation mechanism of active sites on Cu/ZrO2 specific toward CO2-to-methanol hydrogenation. The active sites on Cu/a-ZrO2 (a-: amorphous) were more suitable for CO2-to-methanol hydrogenation than those on Cu/t-ZrO2 (t-: tetragonal) and Cu/m-ZrO2 (m-: monoclinic). When a-ZrO2 was impregnated with a Cu(NO3)2·3H2O solution and then calcined under air, most of the Cu species entered a-ZrO2, leading to the formation of a Cu-Zr mixed oxide (CuaZr1-aOb). The H2 reduction of the thus-formed CuaZr1-aOb led to the formation of Cu nanoparticles on a-ZrO2, which can be dedicated to CO2-to-methanol hydrogenation. We concluded that the selective synthesis of CuaZr1-aOb, especially amorphous CuaZr1-aOb, is a key feature of the catalyst preparation. The preparation conditions of the amorphous CuaZr1-aOb specific toward CO2-to-methanol hydrogenation is as follows: (i) Cu(NO3)2·3H2O/a-ZrO2 is calcined at low temperature (350 °C in this study) and (ii) the Cu loading is low (6 and 8 wt % in this study). Via these preparation conditions, the characteristics of a-ZrO2 for the catalysts remained unchanged during the reaction at 230 °C. The latter preparation condition is related to the solubility limit of Cu species in a-ZrO2. Accordingly, we obtained the amorphous CuaZr1-aOb without forming crystalline CuO particles.
• Catalytic NO-CO Reactions over La-Al2O3 Supported Pd: Promotion Effect of La

  Takashi Toyao, Yuan Jing, Kenichi Kon, Tomoharu Hayama, Shuhei Nagaoka, Ken-ichi Shimizu

  CHEMISTRY LETTERS 47 8 1036 - 1039 2018年08月 [査読有り][通常論文]
   

  Studies were carried out to explore catalytic NO-CO reactions promoted by La-loaded and unloaded Al2O3 supported Pd in both powder and cordierite monolithic honeycomb forms. La introduction significantly enhanced catalytic activity toward the NO-CO reaction. The results of in situ FT-IR studies suggest that the promotion effect of La is a consequence of efficient formation of surface nitrite species and their reactivity upon introduction of CO as a reactant.
• Acceptorless dehydrogenative coupling reactions with alcohols over heterogeneous catalysts

  Siddiki S, M. A. Hakim, Toyao Takashi, Shimizu Ken-ichi

  GREEN CHEMISTRY 20 13 2933 - 2952 2018年07月07日 [査読有り][通常論文]
  
• Solution Synthesis of N,N-Dimethylformamide-Stabilized Iron-Oxide Nanoparticles as an Efficient and Recyclable Catalyst for Alkene Hydrosilylation

  Azuma, Ryusei, Nakamichi, Seiya, Kimura, Jungo, Yano, Hiroki, Kawasaki, Hideya, Suzuki, Takeyuki, Kondo, Ryota, Kanda, Yasuharu, Shimizu, Ken-ichi, Kato, Kazuo, Obora, Yasushi

  CHEMCATCHEM 10 11 2378 - 2382 2018年06月 [査読有り][通常論文]
   

  Highly activated, monodispersed N,N-dimethylformamide (DMF)-stabilized iron-oxide nanoparticles (Fe2O3 NPs) were synthesized by using iron(III) acetylacetonate as a precursor under open-air conditions. The resulting Fe2O3 NPs were characterized by various techniques (e.g., transmission electron microscopy, dynamic light scattering, X-ray diffraction, X-ray photoelectron spectroscopy, FTIR spectroscopy, and X-ray adsorption near-edge structure). The Fe2O3 NPs exhibited efficient catalytic activity for the hydrosilylation of alkenes without the need for further additives. An effective recycling process of the colloidal catalyst by extraction with a hexane/DMF system was developed, and recycling of the catalyst over five cycles did not result in any significant loss in catalytic activity.
• Combined theoretical and experimental study on alcoholysis of amides on CeO2 surface: A catalytic interplay between Lewis acid and base sites

  Takashi Kamachi, S.M.A. Hakim Siddiki, Yoshitsugu Morita, Md. Nurnobi Rashed, Kenichi Kon, Takashi Toyao, Ken-ichi Shimizu, Kazunari Yoshizawa

  Catalysis Today 303 256 - 262 2018年04月01日 [査読有り][通常論文]
   

  Alcoholysis of amides on the CeO2 surface is investigated from density functional theory (DFT) computations, in situ FT-IR spectroscopy, and catalytic studies. The thermodynamically stable amide bonds are effectively activated by the CeO2 catalyst under mild conditions in contrast to other metal oxide catalysts. DFT calculations demonstrated that acetamide adsorbed on the CeO2 surface is attacked by lattice oxygen to give a tetrahedral intermediate in the rate-determining step of the most favorable pathway. This is consistent with the experimental finding that the activity of metal oxide catalysts increases with an increase of the base strength of the catalyst. The strong base sites of CeO2 are the most important factor for the high reactivity. Interestingly, the nucleophilic attack of lattice oxygen is further assisted by the moderately strong Ce4+ Lewis acid sites. Our computational results show that the high reactivity is ascribed to a catalytic interplay between the Lewis base and acid pair sites on the CeO2 surface.
• Toward Effective Utilization of Methane: Machine Learning Prediction of Adsorption Energies on Metal Alloys

  Takashi Toyao, Keisuke Suzuki, Shona Kikuchi, Satoru Takakusagi, Ken-ichi Shimizu, Ichigaku Takigawa

  JOURNAL OF PHYSICAL CHEMISTRY C 122 15 8315 - 8326 2018年04月 [査読有り][通常論文]
   

  The process employed to discover new materials for specific applications typically utilizes screening of large compound libraries. In this approach, the performance of a compound is correlated to the properties of elements referred to as descriptors. In the effort described below, we developed a simple and efficient machine learning (ML) model for predicting adsorption energies of CH4 related species, namely, CH3, CH2, CH, C, and H on the Cu-based alloys. The developed ML model predicted the DFT-calculated adsorption energies with 12 descriptors, which are readily available values for the selected elements. The predictive accuracy of four regression methods (ordinary linear regression by least-squares (OLR), random forest regression (RFR), gradient boosting regression (GBR), and extra tree regression (ETR)) with different numbers of descriptors and different test-set/training-set ratios was quantitatively evaluated using statistical cross validations. Among four types of regression methods, we have found that ETR gave the best performance in predicting the adsorption energies with the average root mean squared errors (RMSEs) below 0.3 eV. Strikingly, despite its simplicity and low computational cost, this model can predict the adsorption energies on a range of Cu-based alloy models (46 in total number) as calculated by using DFT. In addition, we show the ML prediction for the differences in the adsorption energies of CH3 and CH2 on the same surface. This would be of great importance especially when designing the selective catalytic reaction processes to suppress the undesired over-reactions. The accuracy and simplicity of the developed system suggest that adsorption energies can be readily predicted without time-consuming DFT calculations, and eventually, this would allow us to predict the catalytic performances of the solid catalysts.
• C-Methylation of Alcohols, Ketones, and Indoles with Methanol Using Heterogeneous Platinum Catalysts

  Siddiki S, M. A. Hakim, Touchy Abeda S, Jamil Md. A. R, Toyao Takashi, Shimizu Ken-ichi

  ACS CATALYSIS 8 4 3091 - 3103 2018年04月 [査読有り][通常論文]
  
• Machine learning predictions of factors affecting the activity of heterogeneous metal catalysts

  Takigawa Ichigaku, Shimizu Ken-ichi, Tsuda Koji, Takakusagi Satoru

  ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY 255 2018年03月18日 [査読有り][通常論文]
  
• Direct Synthesis of Lactams from Keto Acids, Nitriles, and H2 by Heterogeneous Pt Catalysts

  S. M.A.H. Siddiki, Abeda S. Touchy, Ashvini Bhosale, Takashi Toyao, Yuji Mahara, Junya Ohyama, Atsushi Satsuma, Ken-Ichi Shimizu

  ChemCatChem 10 4 789 - 795 2018年02月21日 [査読有り][通常論文]
   

  We report herein the first general catalytic system for the direct synthesis of N-substituted γ- and δ-lactams by reductive amination/cyclization of keto acids (including levulinic acid) with nitriles and H2 under mild conditions (7 bar H2, 110 °C, solvent free). The most effective catalyst, Pt and MoOx co-loaded TiO2 (Pt-MoOx/TiO2), shows a wide substrate scope, high turnover number (TON), and good reusability.
• NH₃-SCR用ゼオライト触媒開発の次の展開

  小倉 賢, 江原 正博, 窪田 好浩, 清水 研一, 津野地 直, 横井 俊之

  石油学会 年会・秋季大会講演要旨集 2018f 40  公益社団法人 石油学会 2018年 

  自動車用内燃機関技術研究組合AICEの旗印の下、日本のゼオライト研究者が集結して新しいゼオライトを自動車後処理技術に適用することを目的として研究をスタートさせた。AICE第2期に入り、第1期で見出されたゼオライトをどのような形で実効性の高いものへ近づけるかの研究をスタートさせたので、これを一部紹介したい。
• Rhenium-Loaded TiO2 : A Highly Versatile and Chemoselective Catalyst for the Hydrogenation of Carboxylic Acid Derivatives and the N-Methylation of Amines Using H2 and CO2.

  Takashi Toyao, S M A H Siddiki, Yoshitsugu Morita, Takashi Kamachi, Abeda S Touchy, Wataru Onodera, Kenichi Kon, Shinya Furukawa, Hiroko Ariga, Kiyotaka Asakura, Kazunari Yoshizawa, Ken-Ichi Shimizu

  Chemistry (Weinheim an der Bergstrasse, Germany) 23 59 14848 - 14859 2017年10月20日 [査読有り][通常論文]
   

  Herein, we report a heterogeneous TiO2 -supported Re catalyst (Re/TiO2 ) that promotes various selective hydrogenation reactions, which includes the hydrogenation of esters to alcohols, the hydrogenation of amides to amines, and the N-methylation of amines, by using H2 and CO2 . Initially, Re/TiO2 was evaluated in the context of the selective hydrogenation of 3-phenylpropionic acid methyl ester to afford 3-phenylpropanol (pH2 =5 MPa, T=180 °C), which revealed a superior performance over other catalysts that we tested in this study. In contrast to other typical heterogeneous catalysts, hydrogenation reactions with Re/TiO2 did not produce dearomatized byproducts. DFT studies suggested that the high selectivity for the formation of alcohols in favor of the hydrogenation of aromatic rings is ascribed to the higher affinity of Re towards the COOCH3 group than to the benzene ring. Moreover, Re/TiO2 showed a wide substrate scope for the hydrogenation reaction (19 examples). Subsequently, this Re/TiO2 catalyst was applied to the hydrogenation of amides, the N-methylation of amines, and the N-alkylation of amines with carboxylic acids or esters.
• Hydrodeoxygenation of Fatty Acids, Triglycerides, and Ketones to Liquid Alkanes by a Pt-MoOx/TiO2 Catalyst

  Kenichi Kon, Takashi Toyao, Wataru Onodera, S. M. A. H. Siddiki, Ken-ichi Shimizu

  CHEMCATCHEM 9 14 2822 - 2827 2017年07月 [査読有り][通常論文]
   

  Various supported metal catalysts are screened for hydrogenation of lauric acid and 2-octanone as model reactions for the transformation of biomass-derived oxygenates to liquid alkanes (biofuels) in a batch reactor under solvent-free conditions. Among the catalysts tested, Pt and MoOx co-loaded on TiO2 (Pt-MoOx/TiO2) shows the highest yields of n-alkanes for both of the reactions. Pt-MoOx/TiO2 selectively catalyzes the hydrodeoxygenation of various fatty acids and triglycerides to n-alkanes without C-C bond cleavage under 50 bar H-2 and shows higher turnover numbers than the catalysts in the literature. Pt-MoOx/TiO2 is effective also for the hydrodeoxygenation of various ketones to the corresponding alkanes. In situ IR study of the reaction of adsorbed acetone under H-2 suggests that the high activity of Pt-MoOx/TiO2 is attributed to the cooperation between Pt and Lewis acid sites of the MoOx/TiO2 support.
• Oxidant-free Dehydrogenation of Glycerol to Lactic Acid by Heterogeneous Platinum Catalysts

  S. M. A. Hakim Siddiki, Abeda S. Touchy, Kenichi Kon, Takashi Toyao, Ken-ichi Shimizu

  CHEMCATCHEM 9 14 2816 - 2821 2017年07月 [査読有り][通常論文]
   

  Among various supported metal nanoparticle catalysts, Pt-loaded carbon (Pt/C) catalysts, including a commercial one, showed the highest yield for selective dehydrogenation of glycerol to lactic acid under oxidant-free, solvent-free, and alkaline conditions. For the reaction with Pt/C, the effects of conditions (type of basic additives, the amount of water, atmosphere, reactor) on the catalytic activity and selectivity were studied. Combined with a reaction pathway in the literature and our result of control reactions, we proposed a strategy for decreasing the selectivity of by products. The optimized conditions gave a high turnover number of 69000. To clarify the structural factors affecting the catalytic activity, we show the effect of electronic states of various transition metals on the activity as well as the effect of Pt particle size on the turnover frequency per surface Pt atom.
• Heterogeneous catalysts for the cyclization of dicarboxylic acids to cyclic anhydrides as monomers for bioplastic production

  Md N. Rashed, S. M. A. H. Siddiki, Md A. Ali, Sondomoyee K. Moromi, Abeda S. Touchy, Kenichi Kon, Takashi Toyao, Ken-ichi Shimizu

  GREEN CHEMISTRY 19 14 3238 - 3242 2017年07月 [査読有り][通常論文]
   

  Cyclic anhydrides, key intermediates of carbon-neutral and biodegradable polyesters, are currently produced from biomass-derived dicarboxylic acids by a high-cost multistep process. We present a new high-yielding process for the direct intramolecular dehydration of dicarboxylic acids using a reusable heterogeneous Lewis acid catalyst, Nb2O5 center dot nH(2)O. Various dicarboxylic acids, which can be produced by a biorefinery process, are transformed into the corresponding cyclic anhydrides as monomers for polyester production. This method is suitable for the production of renewable polyesters in a biorefinery process.
• Promotional Effect of Water on Direct Dimethyl Ether Synthesis from Carbon Monoxide and Hydrogen Catalyzed by Cu-Zn/Al2O3

  Kaoru Takeishi, Yutaro Wagatsurna, Hiroko Ariga, Kenichi Kon, Ken-ichi Shimizu

  ACS SUSTAINABLE CHEMISTRY & ENGINEERING 5 5 3675 - 3680 2017年05月 [査読有り][通常論文]
   

  Cu-Zn/Al2O3 was prepared by using the sol gel method and employed for the direct synthesis of dimethyl ether (DME) from synthesis gas (syngas) in a continuous-flow reactor. We studied the effect of water concentration in the feed on the formation rates of various products. With an increase in the amount of water, the formation rate of DME initially increased and then decreased. Co-feeding of 0.09% water was co-fed resulting in the highest formation rate of DME, 486 mu mol g(cat)(-1) h(-1) (8.0% yield of DME), at 220 degrees C under 0.9 MPaG. Structural studies by XANES, EXAFS, XPS, and infrared spectroscopies showed that the treatment of the catalyst with 0.66% water at 240 C under atmospheric pressure resulted in oxidation of the metallic copper species and increased the number of surface Cu+ sites. Combined with the catalytic results, we conclude that the increase in the surface Cu+ sites is responsible for the promotion effect of steam on the DME production.
• Acceptorless dehydrogenation of N-heterocycles by supported Pt catalysts

  Sondomoyee K. Moromi, S. M. A. H. Siddiki, Kenichi Kon, Takashi Toyao, Ken-ichi Shimizu

  CATALYSIS TODAY 281 507 - 511 2017年03月 [査読有り][通常論文]
   

  Pt metal nanoparticles loaded on various supports and carbon-supported various metal catalysts are tested for dehydrogenation of 6-methyl-1,2,3,4- tetrahydroquinoline to 6-methyl-quinoline under oxidant-free conditions. In the 20 types of the catalysts screened, carbon-supported Pt catalyst (Pt/C) shows the highest activity. Pt/C is reusable after the reaction and is effective for dehydrogenation of various N-heterocycles (tetrahydroquinolines and indoline). Pt/C is also effective for hydrogenation of quinoline under 3 bar H-2. The results demonstrate that this catalytic method may be useful for an organic hidride-based hydrogen storage system. (C) 2016 Elsevier B.V. All rights reserved.
• Interface Effects in Hydrogen Elimination Reaction from Isopropanol by Ni-13 Cluster on theta-Al2O3(010) Surface

  Andrey Lyalin, Ken-ichi Shimizu, Tetsuya Taketsugut

  JOURNAL OF PHYSICAL CHEMISTRY C 121 6 3488 - 3495 2017年02月 [査読有り][通常論文]
   

  We present results of theoretical investigation on catalytic hydrogen elimination from isopropanol (C3H8O) by free and (theta-Al2O3(010)-supported Ni-13 cluster. The specific role played by the perimeter interface between the nickel cluster and alumina support is discussed. It is demonstrated that dehydrogenation of C3H8O on the free Ni-13 cluster is a two-step process with the first hydrogen elimination from the alcohol hydroxyl group, followed by C-H bond cleavage. Our calculations show that H elimination from OH group of C3H8O to Ni-13 cluster is the rate-determining step with the barrier of 0.95 eV, while the C-H bond cleavage requires overcoming the barrier of 0.41 eV. In the case of Ni-13 cluster supported on (theta-Al2O3(010) the isopropanol molecule adsorbs on top of the surface Al atom in the close vicinity of the nickel cluster, which results in considerable decrease in barrier for H elimination due to formation of the complementary adsorption sites at the metal/support interface. It is demonstrated that intermediate formation of the Ni-C bond considerably promotes C-H bond cleavage. The described mechanism provides fundamental understanding of the process of the oxidant-free catalytic hydrogen elimination from alcohols on supported nickel clusters and can serve as a tool for rational design of novel type of nanocatalysts based on abundant noble-metal-free materials.
• TiO2 -Supported Re as a General and Chemoselective Heterogeneous Catalyst for Hydrogenation of Carboxylic Acids to Alcohols.

  Takashi Toyao, S M A Hakim Siddiki, Abeda S Touchy, Wataru Onodera, Kenichi Kon, Yoshitsugu Morita, Takashi Kamachi, Kazunari Yoshizawa, Ken-Ichi Shimizu

  Chemistry (Weinheim an der Bergstrasse, Germany) 23 5 1001 - 1006 2017年01月23日 [査読有り][通常論文]
   

  TiO2 -supported Re, Re/TiO2 , was found to promote selective hydrogenation of carboxylic acids having aromatic and aliphatic moieties to the corresponding alcohols. Re/TiO2 showed superior results compared to other transition-metal-loaded TiO2 and supported Re catalysts for selective hydrogenation of 3-phenylpropionic acid. 3-phenylpropanol was produced in 97 % yield under mild conditions (5 MPa H2 at 140 °C). Contrary to typical heterogeneous catalysts, Re/TiO2 does not lead to the formation of dearomatized byproducts. The catalyst is recyclable and shows a wide substrate scope in the synthesis of alcohols (22 examples; up to 97 % isolated yield).
• TiO2-Supported Re as a General and Chemoselective Heterogeneous Catalyst for Hydrogenation of Carboxylic Acids to Alcohols

  Kenichi Kon, Ken-ichi Shimizu, Takashi Toyao, S. M. A. Hakim Siddiki, Abeda S. Touchy, Wataru Onodera

  CHEMISTRY-A EUROPEAN JOURNAL 23 5 980 - 980 2017年01月 [査読有り][通常論文]
  
• Heterogeneous Platinum Catalysts for Direct Synthesis of Trimethylamine by N-Methylation of Ammonia and Its Surrogates with CO2/H-2

  Takashi Toyao, S. M. A. Hakim Siddiki, Keisuke Ishihara, Kenichi Kon, Wataru Onodera, Ken-ichi Shimizu

  CHEMISTRY LETTERS 46 1 68 - 70 2017年01月 [査読有り][通常論文]
   

  Direct synthesis of trimethylamine through N-methylation of NH3 or its surrogate (NH4HCO3) with both CO2 and H-2 has been achieved by employing Pt and MoOx coloaded TiO2 (Pt-MoOx/TiO2). Pt-MoOx/TiO2 was found to be superior to other supported Pt and transition-metal-loaded MoOx/TiO2 catalysts for the trimethylamine synthesis process.
• NH3-efficient ammoxidation of toluene by hydrothermally synthesized layered tungsten-vanadium complex metal oxides

  Yoshinori Goto, Ken-ichi Shimizu, Kenichi Kon, Takashi Toyao, Toru Murayama, Wataru Ueda

  JOURNAL OF CATALYSIS 344 346 - 353 2016年12月 [査読有り][通常論文]
   

  Hydrothermally synthesized W-V-O layered metal oxides (W-V-O) are studied for the vapor phase ammoxidation of toluene to benzonitrile (PhCN). Under similar conversion levels at 400 degrees C, W-V-O shows higher selectivity (based on toluene) to PhCN and lower selectivity to COx than conventional V-based catalysts (V2O5 and VOx/TiO2). Under the conditions of high contact time, W-V-O shows 99.7% conversion of toluene and 93.5% selectivity to PhCN. Another important feature of W-V-O is high NH3-utilization efficiency in ammoxidation, which originates from the lower activity of W-V-O for NH3 oxidation than that of V2O5. In situ infrared (IR) study shows that toluene is oxidized by the surface oxygen species of W83V17 to yield benzaldehyde which undergoes the reaction with adsorbed NH3 to give benzonitrile. Model reaction studies with W-V-O suggest that the rate of NH3 conversion to PhCN in the benzaldehyde + NH3 + O-2 reaction is 3 times higher than the rate of NH3 oxidation to N-2 in the NH3 + 02 reaction. It is shown that the high NH3-efficiency of W-V-O is caused by the preferential reaction of NH3 in PhCHO + NH3 + O-2 over NH3+O-2 reaction. (C) 2016 Elsevier Inc. All rights reserved.
• Catalytic hydrolysis of hydrophobic esters on/in water by high-silica large pore zeolites

  S. M. A. H. Siddiki, Takashi Toyao, Kenichi Kon, Abeda S. Touchy, Ken-ichi Shimizu

  JOURNAL OF CATALYSIS 344 741 - 748 2016年12月 [査読有り][通常論文]
   

  Hydrolysis of water-insoluble esters is an industrially important but challenging reaction, because the esters are mostly present in oil droplets on water during the reaction. On the basis of the screening results for hydrolysis of a water-insoluble ester, 3-phenylpropionate, on/in water by 25 types of heterogeneous and homogenous catalysts, we have found that H beta zeolite with a moderate Si/Al ratio (Si/Al = 75), H beta-75, is an effective and reusable catalyst for hydrolysis of hydrophobic esters. The hydrolysis of esters with different sizes is studied by H beta and HZSM5 zeolites with different Si/Al ratios, and the results show the hydrophobicity, pore size and number of Bronsted acid sites are critical factors affecting the catalytic activity for this system. Kinetic and adsorption studies show that the high yields by H beta-75 are due to preferential interaction of the hydrophobic zeolite pore with hydrophobic esters over polar molecules (carboxylic acids, water, alcohols) and transfer of the carboxylic acids to the oil droplets on water, both of which inhibit the reverse reaction (esterification of the carboxylic acids). (C) 2016 Elsevier Inc. All rights reserved.
• Atomic-Resolution HAADF-STEM Study of Ag/Al2O3 Catalysts for Borrowing-Hydrogen and Acceptorless Dehydrogenative Coupling Reactions of Alcohols

  Kenta Yoshida, Kenichi Kon, Ken-ichi Shimizu

  TOPICS IN CATALYSIS 59 19-20 1740 - 1747 2016年12月 [査読有り][通常論文]
   

  We study HAADF-STEM analysis of Ag/Al2O3 samples (as-calcined and reduced at 25, 300, 500 and 900 degrees C). Ag atoms are classified into subnanoclusters (0.3-1 nm), nanoclusters (1-3 nm), nanoparticles (3-10 nm) and polycrystals ([10 nm). The size of Ag increases with the reduction temperature, which is supported by EXAFS analysis. The effect of Ag size on the activity for borrowing-hydrogen and acceptorless dehydrogenative couplings of alcohols is discussed.
• Direct Olefination of Alcohols with Sulfones by Using Heterogeneous Platinum Catalysts.

  S M A Hakim Siddiki, Abeda Sultana Touchy, Kenichi Kon, Ken-Ichi Shimizu

  Chemistry (Weinheim an der Bergstrasse, Germany) 22 17 6111 - 9 2016年04月18日 [査読有り][通常論文]
   

  Carbon-supported Pt nanoparticles (Pt/C) were found to be effective heterogeneous catalysts for the direct Julia olefination of alcohols in the presence of sulfones and KOtBu under oxidant-free conditions. Primary alcohols, including aryl, aliphatic, allyl, and heterocyclic alcohols, underwent olefination with dimethyl sulfone and aryl alkyl sulfones to give terminal and internal olefins, respectively. Secondary alcohols underwent methylenation with dimethyl sulfone. Under 2.5 bar H2, the same reaction system was effective for the transformation of alcohol OH groups to alkyl groups. Structural and mechanistic studies of the terminal olefination system suggested that Pt(0) sites on the Pt metal particles are responsible for the rate-limiting dehydrogenation of alcohols and that KOtBu may deprotonate the sulfone reagent. The Pt/C catalyst was reusable after the olefination, and this method showed a higher turnover number (TON) and a wider substrate scope than previously reported methods, which demonstrates the high catalytic efficiency of the present method.
• Direct Synthesis of Cyclic Imides from Carboxylic Anhydrides and Amines by Nb2O5 as a Water-Tolerant Lewis Acid Catalyst

  Md. A. Ali, Sondomoyee K. Moromi, Abeda S. Touchy, Ken-ichi Shimizu

  CHEMCATCHEM 8 5 891 - 894 2016年03月 [査読有り][通常論文]
   

  In the 20 types of heterogeneous and homogenous catalysts screened, Nb2O5 showed the highest activity for the synthesis of N-phenylsuccinimide by dehydrative condensation of succinic anhydride and aniline. Nb2O5 was used in the direct imidation of a wide range of carboxylic anhydrides with NH3 or amines with various functional groups and could be reused. Kinetic studies showed that the Lewis acid Nb2O5 catalyst was more water tolerant than both the Lewis acidic oxide TiO2 and the homogeneous Lewis acid ZrCl4, which resulted in higher yields of imides through the use of Nb2O5.
• 担持白金触媒上でのスルホンとアルコールからのアルケン・アルキンの合成

  清水 研一, Siddiki S. M. A. Hakim, 今 健一

  石油学会 年会・秋季大会講演要旨集 2016 26 - 26 公益社団法人 石油学会 2016年 

  種々の担持白金触媒によるスルホンとアルコールからのアルケン合成を検討したところ、Pt/Cが最も高活性を示した。Pt/Cは種々のアルコールとスルホンからの末端・内部アルケンの合成に有効であった。反応条件を変更すると、同一触媒系からアルキンを選択的に合成することも可能であった。
• Synthesis of 2,5-disubstituted pyrroles via dehydrogenative condensation of secondary alcohols and 1,2-amino alcohols by supported platinum catalysts

  S. M. A. H. Siddiki, Abeda S. Touchy, Chandan Chaudhari, Kenichi Kon, Takashi Toyao, Ken-ichi Shimizu

  ORGANIC CHEMISTRY FRONTIERS 3 7 846 - 851 2016年 [査読有り][通常論文]
   

  Direct synthesis of 2,5-disubstituted pyrroles has been achieved via acceptorless dehydrogenative heterocyclization of 1,2-aminoalcohols and secondary alcohols by utilizing a heterogeneous carbon-supported Pt catalyst (Pt/C). The optimized method gave 92% yield of 2-ethyl-5-phenyl-1H-pyrrole as a desired product from 2-amino-1-butanol and 1-phenylethanol in the presence of 0.1 mol% of Pt/C and 1.1 equiv. of KOtBu. It has been revealed that Pt/C demonstrates superior catalytic activity to a number of catalysts tested in this study including other transition metal-loaded carbon and various metal-oxide-supported Pt catalysts. In addition, the turnover number (TON) obtained in the present system was found to be higher than those obtained in previously-reported catalytic systems. It is significant that the Pt/C catalyst could be recycled as a heterogeneous catalyst without significant loss in the activity and showed a wide substrate scope for the 2,5-disubstituted pyrrole forming process.
• Supported rhenium nanoparticle catalysts for acceptorless dehydrogenation of alcohols: structure-activity relationship and mechanistic studies

  Kenichi Kon, Wataru Onodera, Takashi Toyao, Ken-ichi Shimizu

  CATALYSIS SCIENCE & TECHNOLOGY 6 15 5864 - 5870 2016年 [査読有り][通常論文]
   

  Al2O3-supported Re with different oxidation states and Re-0 metal nanoparticles on various supports are prepared, characterized and tested for the dehydrogenation of 2-octanol. The activity of Re/Al2O3 increases with the fraction of metallic Re. The activity of metallic Re depends on the support oxides, and the support with moderate electronegativity (Al2O3) gives the highest turnover frequency (TOF) per surface Re-0 site. Re/Al2O3 is effective for acceptorless dehydrogenation of various aliphatic secondary alcohols to ketones. The kinetic isotope effects on the dehydrogenation of 2-propanol show that dissociation of the alpha-C-H bond of 2-propanol is the rate-limiting step. The IR study of the reaction of gas phase 2-propanol over the Re/Al2O3 surface shows that the acid-base pair site of Al2O3 is responsible for the O-H dissociation of 2-propanol. The structural requirements are discussed on the basis of the mechanistic results.
• Machine-learning prediction of the d-band center for metals and bimetals

  Ichigaku Takigawa, Ken-ichi Shimizu, Koji Tsuda, Satoru Takakusagi

  RSC ADVANCES 6 58 52587 - 52595 2016年 [査読有り][通常論文]
   

  The d-band center for metals has been widely used in order to understand activity trends in metal-surface-catalyzed reactions in terms of the linear Bronsted-Evans-Polanyi relation and Hammer-Norskov d-band model. In this paper, the d-band centers for eleven metals (Fe, Co, Ni, Cu, Ru, Rh, Pd, Ag, Ir, Pt, Au) and their pairwise bimetals for two different structures (1% metal doped- or overlayer-covered metal surfaces) are statistically predicted using machine learning methods from readily available values as descriptors for the target metals (such as the density and the enthalpy of fusion of each metal). The predictive accuracy of four regression methods with different numbers of descriptors and different test-set/training-set ratios are quantitatively evaluated using statistical cross validations. It is shown that the d-band centers are reasonably well predicted by the gradient boosting regression (GBR) method with only six descriptors, even when we predict 75% of the data from only 25% given for training (average root mean square error (RMSE) < 0.5 eV). This demonstrates a potential use of machine learning methods for predicting the activity trends of metal surfaces with a negligible CPU time compared to first-principles methods.
• Hydrothermal synthesis of microporous W-V-O as an efficient catalyst for ammoxidation of 3-picoline

  Yoshinori Goto, Ken-ichi Shimizu, Toru Murayama, Wataru Ueda

  APPLIED CATALYSIS A-GENERAL 509 118 - 122 2016年01月 [査読有り][通常論文]
   

  W-V complex metal oxide (W-V-O) was prepared by hydrothermal synthesis method. Characterization by XRD, XPS, ICP-AES, N-2 adsorption, and STEM showed that W-V-O had a layered structure with micropore. W-V-O was tested for the vapor phase ammoxidation of 3-picoline (PIC) to 3-cyanopyridine (CP) and compared with VOx/WO3 catalyst prepared by impregnation method and other V-based catalysts which were reported to be efficient for this reaction. W-added vanadium oxides, W-V-O and VOx/WO3, showed higher CP selectivity than conventional catalysts such as VOx/TiO2. The W-V-O catalyst showed the highest CP selectivity of 99.5% at full PIC conversion. Kinetic studies showed that CP was the primary product and small amount of pyridine and CO2 were produced from CP. The reaction by W-V-O in low NH3 concentration condition or without co-feeding of water was also studied to evaluate the catalytic performance of W-V-O in industrially relevant conditions. (C) 2015 Elsevier B.V. All rights reserved.
• Hydrosilane-Assisted Formation of Metal Nanoparticles on Graphene Oxide

  Akinori Saito, Hiroshi Kinoshita, Ken-ichi Shimizu, Yuta Nishina

  BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 89 1 67 - 73 2016年01月 [査読有り][通常論文]
   

  Metal nanoparticles were formed on graphene oxide by a deposition process with hydrosilane, giving thin layer metal graphene oxide (metal/GO) composites. The particle size and catalytic activity could be controlled by varying the hydrosilane amount. Hydrosilane prevented the aggregation of GO layers by surface functionalization via silane coupling reaction. The metal/GO composites were evaluated as catalysts in hydrosilane oxidation.
• Hydrodeoxygenation of sulfoxides to sulfides by a Pt and MoOx co-loaded TiO2 catalyst

  Abeda Sultana Touchy, S. M. A. Hakim Siddiki, Wataru Onodera, Kenichi Kona, Ken-ichi Shimizu

  GREEN CHEMISTRY 18 8 2554 - 2560 2016年 [査読有り][通常論文]
   

  Supported metal nanoparticle catalysts were studied for the hydrodeoxygenation of sulfoxides to sulfides under solvent-free and mild conditions (50-155 degrees C, 1 or 7 atm H-2). The catalytic activity for the model reaction of diphenyl sulfoxide depended on the type of metals, support materials and co-loaded oxides of transition metals (V, Nb, Mo, W, Re). Pt and MoOx co-loaded TiO2 (Pt-MoOx/TiO2) showed the highest activity. Pt-MoOx/TiO2 was reusable after the reaction and was effective for the reduction of various sulfoxides and showed a higher turnover number (TON) than previously reported catalysts. Using Pt-MoOx/TiO2, benzylphenylsulfone was reduced by H-2 to give phenylbenzyl sulfide via benzylphenyl sulfoxides, which represented the first example of catalytic conversion of a sulfone to a sulfide by H-2. Characterization studies of Pt-MoOx/TiO2 show that the surface of TiO2 is covered by small (or thin layer) Mo oxide species with exposed Mo cations as Lewis acid sites, and 4-5 nm sized Pt metal nanoparticles are supported on the Mo oxide-covered TiO2.
• Low temperature combustion over supported Pd catalysts - Strategy for catalyst design

  Atsushi Satsuma, Kaoru Osaki, Masatoshi Yanagihara, Junya Ohyama, Kenichi Shimizu

  CATALYSIS TODAY 258 83 - 89 2015年12月 [査読有り][通常論文]
   

  Supported Pd is an essential component for automobile three-way catalyst (TWC). Recent improvement of fuel economy in automobiles requires promotion of catalytic activity of TWC at lower temperatures, especially for combustion of CO and unburned hydrocarbons. In order to obtain a strategy for catalyst design of supported Pd catalysts for low temperature combustion, the essential factors in catalytic activity affected by supports and oxidation states of Pd are summarized in this short review. The following factors are discussed: oxidation states of Pd, effect of substrates and reaction temperature, Pd dispersion, and oxygen storage-release property of supports. The reducibility of Pd species and oxygen storage-release property of supports are emphasized as essential factors for low temperature combustion over supported Pd catalysts. (C) 2015 Elsevier B.V. All rights reserved.
• Amidation of Carboxylic Acids with Amines by Nb2O5 as a Reusable Lewis Acid Catalyst

  Md. A. Ali, S. M. A. H. Siddiki, Wataru Onodera, Kenichi Kon, Ken-ichi Shimizu

  ChemCatChem 7 21 3555 - 3561 2015年11月 [査読有り][通常論文]
   

  Among 28 types of heterogeneous and homogenous catalysts tested, Nb2O5 shows the highest yield for direct amidation of n-dodecanoic acid with a less reactive amine (aniline). The catalytic amidation by Nb2O5 is applicable to a wide range of carboxylic acids and amines with various functional groups, and the catalyst is reusable. A comparison of the results of the catalytic study and an infrared study of the acetic acid adsorbed on the catalyst suggests that activation of the carbonyl group of the carboxylic acid by Lewis acid sites on Nb2O5 is responsible for the high activity of the Nb2O5 catalyst. Kinetic studies show that Lewis acid sites on Nb2O5 are more water-tolerant than conventional Lewis acidic oxides (Al2O3, TiO2). In comparison with the state-of-the-art homogeneous Lewis acid catalyst for amidation (ZrCl4), Nb2O5 undergoes fewer negative effects from basic additives in the solution, which indicates that Nb2O5 is a more base-tolerant Lewis acid catalyst than the homogeneous Lewis acid catalyst.
• A Heterogeneous Niobium(V) Oxide Catalyst for the Direct Amidation of Esters

  Md. Ayub Ali, S. M. A. Hakim Siddiki, Kenichi Kon, Ken-ichi Shimizu

  CHEMCATCHEM 7 17 2705 - 2710 2015年09月 [査読有り][通常論文]
   

  This study reports the first example of a heterogeneous catalytic system for the direct amidation of various esters with amines. Of 25 types of catalyst, Nb2O5 shows the highest activity in the amidation of methyl benzoate with aniline. Nb2O5 gives high yields in the amidation of various esters and amines under solvent-free conditions, is reusable, and shows higher turnover numbers than previously reported homogeneous catalysts such as La(OTf)(3). IR spectroscopic studies of ethyl acetate adsorbed on the catalysts show a strong acid-base interaction between the Nb5+ Lewis acid site and carbonyl oxygen, which can result in high reactivity of the ester with a nucleophile (amine) and, thus, high activity of Nb2O5. Kinetic results show that the activity of Nb2O5 does not markedly decrease with increasing aniline concentration, in contrast to reference catalysts TiO2 and La(OTf)(3). The relatively low negative impact of basic molecules on the Lewis acid catalysis of Nb2O5 also enables its high activity.
• Acceptorless dehydrogenative synthesis of benzothiazoles and benzimidazoles from alcohols or aldehydes by heterogeneous Pt catalysts under neutral conditions

  Chandan Chaudhari, S. M. A. Hakim Siddiki, Ken-ichi Shimizu

  TETRAHEDRON LETTERS 56 34 4885 - 4888 2015年08月 [査読有り][通常論文]
   

  Pt/Al2O3 and Pt/TiO2 were effective catalysts for the synthesis of 2-substituted benzimidazoles from 2-aminothiophenol and 1,2-phenylenediamine with alcohols acceptor-free and additive-free conditions. (C) 2015 Elsevier Ltd benzothiazoles and or aldehydes under. All rights reserved.
• Highly durable platelet carbon nanofiber-supported platinum catalysts for the oxygen reduction reaction

  Etsushi Tsuji, Takenori Yamasaki, Yoshitaka Aoki, Soo-Gil Park, Ken-ichi Shimizu, Hiroki Habazaki

  CARBON 87 1 - 9 2015年06月 [査読有り][通常論文]
   

  We report the preparation and characterization of highly durable platinum catalysts supported on platelet-structure carbon nanofibers (Pt/p-CNFs) for the oxygen reduction reaction. The p-CNFs were prepared by liquid phase carbonization of polyvinyl chloride using a porous anodic alumina template at 600 degrees C; their degree of graphitization was increased by the subsequent heat treatment at higher temperatures of up to 1400 degrees C. The platinum nanoparticles with similar to 3 nm diameter were deposited more uniformly on the p-CNFs compared with those on the commercial Ketjen black (KB). The catalytic activity and durability of the Pt/p-CNFs for the oxygen reduction reaction (ORR) in H2SO4 solution were improved by increasing the heat-treatment temperature of p-CNFs. The durability of the Pt/p-CNFs was much higher than that of Pt/KB; in particular, a loss of less than 10% was observed in the ORR activity of Pt/p-CNF heat-treated at 1400 degrees C after potential cycling from 0.5 to 1.5 V vs. RHE for 200 cycles in an argon-saturated H2SO4 aqueous solution. (C) 2015 Elsevier Ltd. All rights reserved.
• Unprecedented Reductive Esterification of Carboxylic Acids under Hydrogen by Reusable Heterogeneous Platinum Catalysts

  Abeda S. Touchy, Kenichi Kon, Wataru Onodera, Ken-ichi Shimizu

  ADVANCED SYNTHESIS & CATALYSIS 357 7 1499 - 1506 2015年05月 [査読有り][通常論文]
   

  Supported metal catalysts have been tested for an unprecedented reductive dimerization of carboxylic acids to esters under 8 bar hydrogen in solvent-free conditions. Among various metal-loaded tin oxide catalysts, platinum-loaded tin dioxide (Pt/SnO2) shows the highest ester yield for the reaction of dodecanoic acid. Among Pt catalysts on various supports, Lewis acidic oxides, especially SnO2, show high activity. The most active catalyst, 5 wt% Pt/SnO2 reduced at 100 degrees C, is effective for the reductive esterification of various carboxylic acids, and the catalyst is reusable for nine cycles, demonstrating the first successful example for the title reaction. Infrared (IR) studies of a model compound (formic acid) on some metal oxides indicate a strong Lewis acid-base interaction between SnO2 and the carbonyl oxygen. For Pt/SnO2 catalysts with different Pt particle sizes, the activity increases with decreasing size of Pt metal. A cooperative catalysis of the Pt metal nanoparticles and the Sn4+ Lewis acid sites is proposed.
• Selective Synthesis of Primary Amines by Reductive Amination of Ketones with Ammonia over Supported Pt catalysts

  Yoichi Nakamura, Kenichi Kon, Abeda Sultana Touchy, Ken-ichi Shimizu, Wataru Ueda

  CHEMCATCHEM 7 6 921 - 924 2015年03月 [査読有り][通常論文]
   

  Supported platinum catalysts are studied for the reductive amination of ketones under ammonia and hydrogen. For a model reaction with 2-adamantanone, Pt-loaded MoOx/TiO2 (Pt-MoOx/TiO2) shows the highest yield of primary amine. The catalyst is effective for the selective transformation of various aliphatic and aromatic ketones to the corresponding primary amines, which demonstrates the first example of the selective synthesis of primary amines by this reaction. The yield of the amine increases with increase in the negative shift of the CO stretching band in the infrared spectra of adsorbed acetone on the catalysts, suggesting that Lewis acid sites on the support material play an important role in this catalytic system.
• Selective Synthesis of Primary Amines by Reductive Amination of Ketones with Ammonia over Supported Pt catalysts

  Yoichi Nakamura, Kenichi Kon, Abeda Sultana Touchy, Ken-ichi Shimizu, Wataru Ueda

  CHEMCATCHEM 7 6 921 - 924 2015年03月 [査読有り][通常論文]
   

  Supported platinum catalysts are studied for the reductive amination of ketones under ammonia and hydrogen. For a model reaction with 2-adamantanone, Pt-loaded MoOx/TiO2 (Pt-MoOx/TiO2) shows the highest yield of primary amine. The catalyst is effective for the selective transformation of various aliphatic and aromatic ketones to the corresponding primary amines, which demonstrates the first example of the selective synthesis of primary amines by this reaction. The yield of the amine increases with increase in the negative shift of the CO stretching band in the infrared spectra of adsorbed acetone on the catalysts, suggesting that Lewis acid sites on the support material play an important role in this catalytic system.
• Heterogeneous catalysis for the direct synthesis of chemicals by borrowing hydrogen methodology

  Ken-ichi Shimizu

  CATALYSIS SCIENCE & TECHNOLOGY 5 3 1412 - 1427 2015年03月 [査読有り][通常論文]
   

  The development of heterogeneous catalysts for green chemical synthesis is a growing area in catalysis and green-sustainable chemistry. This review summarizes recent examples of hydrogen transfer-type reactions using supported transition metal catalysts with special emphasis on the direct synthesis of chemicals by borrowing hydrogen methodology. The highlighted reactions are: (1) transfer hydrogenation of carbonyl compounds, (2) transfer dehydrogenation of alcohols, (3) N-alkylation of amines or NH3 with alcohols, (4) alkylation of acidic CH2 or CH3 group with alcohols, (5) self-and cross-alkylation of alcohols, (6) N- or C3-alkylation of indoles with alcohols, (7) synthesis of quinolines from nitroarenes and alcohols, (8) synthesis of thioethers from thiols and alcohols, and (9) cross-alkylation of amines with different amines. These catalytic reactions have a common mechanistic feature: a domino dehydrogenation-condensation-hydrogenation sequence of alcohols (or amines) and nucleophiles. A key concept in the catalyst design in some of the systems is the multifunctionality of metal-loaded acidic and/or basic metal oxides, in which the acid and/or base sites selectively catalyze the condensation reactions, and the metal site catalyzes the transfer dehydrogenation of alcohol (or amines) and transfer hydrogenation of the condensation products as intermediates. In comparison with the recent examples of organometallic catalysis with borrowing hydrogen methodology, the advantages of heterogeneous catalysis are discussed in terms of catalytic efficiency and sustainability.
• Selective Synthesis of Primary Amines by Reductive Amination of Ketones with Ammonia over Supported Pt catalysts

  Yoichi Nakamura, Kenichi Kon, Abeda Sultana Touchy, Ken-ichi Shimizu, Wataru Ueda

  CHEMCATCHEM 7 6 921 - 924 2015年03月 [査読有り][通常論文]
   

  Supported platinum catalysts are studied for the reductive amination of ketones under ammonia and hydrogen. For a model reaction with 2-adamantanone, Pt-loaded MoOx/TiO2 (Pt-MoOx/TiO2) shows the highest yield of primary amine. The catalyst is effective for the selective transformation of various aliphatic and aromatic ketones to the corresponding primary amines, which demonstrates the first example of the selective synthesis of primary amines by this reaction. The yield of the amine increases with increase in the negative shift of the CO stretching band in the infrared spectra of adsorbed acetone on the catalysts, suggesting that Lewis acid sites on the support material play an important role in this catalytic system.
• V₂O₃およびMoO₂触媒を用いた分子内水素移行反応によるジオール類転換反応

  中村 陽一, 村山 徹, 清水 研一, 上田 渉

  石油学会 年会・秋季大会講演要旨集 2015 51 - 51 公益社団法人 石油学会 2015年 

  V₂O₃およびMoO₂触媒を用いたジオール転換反応について検討した。V₂O₃およびMoO₂触媒によるプロピレングリコールの転換反応では主生成物としてアセトンが観測され、副生成物としてプロピオンアルデヒドとプロピレンが同程度の選択率で生成した。V₂O₃およびMoO₂触媒によるプロピオンアルデヒドの生成は触媒表面に存在する酸サイトにて進行したと考えられる。本反応メカニズムの詳細を検討したところ、V₂O₃およびMoO₂触媒におけるアセトン生成は、水素移行脱水反応がプロピレングリコールの分子内にて進行すると提案した。
• 担持白金触媒によるアルコールとスルホンからのアルケン・アルキンの直接合成

  Siddiki S. M. A. Hakim, 清水 研一

  石油学会 年会・秋季大会講演要旨集 2015 112 - 112 公益社団法人 石油学会 2015年 

  アルコールとスルフォンからのアルケン及びアルキンの直接合成に有効な担持白金触媒を開発した。種々の担体に担持した白金触媒のなかで、活性炭担持白金触媒が最も有効であった。
• Synthesis of indoles via dehydrogenative N-heterocyclization by supported platinum catalysts

  Sondomoyee Konika Moromi, Abeda Sultana Touchy, S. M. A. Hakim Siddiki, Md. Ayub Ali, Ken-ichi Shimizu

  RSC ADVANCES 5 2 1059 - 1062 2015年 [査読有り][通常論文]
   

  We found the first heterogeneous Pt catalysts (Pt/Nb2O5 and Pt/HBEA) for the synthesis of indoles via acceptorless dehydrogenative cyclization of 2-(2-aminophenyl) ethanol, showing higher turnover number (TON) than previously reported catalysts.
• Substrate-Specific Heterogeneous Catalysis of CeO2 by Entropic Effects via Multiple Interactions

  Masazumi Tamura, Kyoichi Sawabe, Keiichi Tomishige, Atsushi Satsuma, Ken-ichi Shimizu

  ACS CATALYSIS 5 1 20 - 26 2015年01月 [査読有り][通常論文]
   

  Achieving complete substrate specificity through multiple interactions like an enzyme is one of the ultimate goals in catalytic studies. Herein, we demonstrate that multiple interactions between the CeO2 surface and substrates are the origin of substrate-specific hydration of nitriles in water by CeO2, which is exclusively applicable to the nitriles with a heteroatom (N or O) adjacent to the alpha-carbon of the CN group but is not applicable to the other nitriles. Kinetic studies reveal that CeO2 reduces the entropic barrier (T Delta S double dagger) for the reaction of the former reactive substrate, leading to 10(7)-fold rate enhancement compared with the latter substrate. Density functional theory (DFT) calculations confirmed multiple interaction of the reactive substrate with CeO2, as well as preferable approximation and alignment of the nitrile group of the substrate to the active OH group on CeO2 surface. This can lead to the reduction of the entropic barrier. This is the first example of an entropy-driven substrate-specific catalysis of a nonporous metal oxide surface, which will provide a new design strategy for enzyme-inspired synthetic catalysts.
• Selective N-alkylation of indoles with primary alcohols using a Pt/HBEA catalyst

  S. M. A. Hakim Siddiki, Kenichi Kon, Ken-ichi Shimizu

  GREEN CHEMISTRY 17 1 173 - 177 2015年 [査読有り][通常論文]
   

  Pt-loaded HBEA (H+-exchanged BEA zeolite) is found to be an effective and reusable heterogeneous catalyst for regioselective N-alkylation of indoles with primary aliphatic and benzylic alcohols under additive-free conditions driven by the borrowing-hydrogen methodology. Structural and mechanistic studies suggest a cooperative mechanism of the Pt-0 site on Pt metal clusters and the Bronsted acid site of the zeolite, in which the Pt-0 site is responsible for dehydrogenation/hydrogenation steps and the Bronsted acid site is responsible for the regioselective condensation of indoles with aldehydes to the enamine intermediate.
• Acceptorless dehydrogenative lactonization of diols by Pt-loaded SnO2 catalysts

  Abeda Sultana Touchy, Ken-ichi Shimizu

  RSC ADVANCES 5 37 29072 - 29075 2015年 [査読有り][通常論文]
   

  We report herein a new heterogeneous catalytic system for dehydrogenative lactonization of various diols under solvent-free and acceptor-free conditions using 1 mol% of Pt-loaded SnO2, providing the first successful example of acceptorless lactonization of 1,6-hexanediol to epsilon-caprolactone by a heterogeneous catalyst.
• Highly durable carbon-supported Pt catalysts prepared by hydrosilane-assisted nanoparticle deposition and surface functionalization

  Akinori Saito, Hiromi Tsuji, Iwao Shimoyama, Ken-ichi Shimizu, Yuta Nishina

  CHEMICAL COMMUNICATIONS 51 27 5883 - 5886 2015年 [査読有り][通常論文]
   

  Hydrosilane enabled the formation of Pt nanoparticles and the silane functionalization of a carbon support material in one pot. The metal/Si-modified carbon composites are highly durable during catalytic methane oxidation.
• Selective N-alkylation of indoles with primary alcohols using a Pt/HBEA catalyst

  S. M. A. Hakim Siddiki, Kenichi Kon, Ken-ichi Shimizu

  GREEN CHEMISTRY 17 1 173 - 177 2015年 [査読無し][通常論文]
   

  Pt-loaded HBEA (H+-exchanged BEA zeolite) is found to be an effective and reusable heterogeneous catalyst for regioselective N-alkylation of indoles with primary aliphatic and benzylic alcohols under additive-free conditions driven by the borrowing-hydrogen methodology. Structural and mechanistic studies suggest a cooperative mechanism of the Pt-0 site on Pt metal clusters and the Bronsted acid site of the zeolite, in which the Pt-0 site is responsible for dehydrogenation/hydrogenation steps and the Bronsted acid site is responsible for the regioselective condensation of indoles with aldehydes to the enamine intermediate.
• Electrodeposition Study on a Single-crystal Titanium Dioxide Electrode: Platinum on a Niobium-doped Titanium Dioxide(110) Electrode

  Satoru Takakusagi, Takafumi Ogawa, Hiromitsu Uehara, Hiroko Ariga, Ken-ichi Shimizu, Kiyotaka Asakura

  CHEMISTRY LETTERS 43 11 1797 - 1799 2014年11月 [査読有り][通常論文]
   

  Pt was successfully electrodeposited on a Nb-doped TiO2(110) electrode from a solution of 1 mM K-2[PtCl4] and 50 mM H2SO4 using single-pulse chronoamperometry. The morphology of the deposited Pt nanoparticles was sensitive to the deposition potential and holding time. A novel method for the preparation of metal particles on a single-crystal TiO2 surface in a controlled manner has been proposed.
• Versatile and sustainable synthesis of cyclic imides from dicarboxylic acids and amines by Nb2O5 as a base-tolerant heterogeneous Lewis acid catalyst.

  Md Ayub Ali, S M A Hakim Siddiki, Kenichi Kon, Junya Hasegawa, Ken-Ichi Shimizu

  Chemistry (Weinheim an der Bergstrasse, Germany) 20 44 14256 - 60 2014年10月27日 [査読有り][通常論文]
   

  Catalytic condensation of dicarboxylics acid and amines without excess amount of activating reagents is the most atom-efficient but unprecedented synthetic method of cyclic imides. Here we present the first general catalytic method, proceeding selectively and efficiently in the presence of a commercial Nb2 O5 as a reusable and base-tolerant heterogeneous Lewis acid catalyst. The method is effective for the direct synthesis of pharmaceutically or industrially important cyclic imides, such as phensuximide, N-hydroxyphthalimide (NHPI), and unsubstituted cyclic imides from dicarboxylic acid or anhydrides with amines, hydroxylamine, or ammonia.
• Effect of Metal Oxide Promoters on Low Temperature CO Oxidation over Water-Pretreated Pt/Alumina Catalysts

  Atsuko Tomita, Ken-ichi Shimizu, Yutaka Tai

  CATALYSIS LETTERS 144 10 1689 - 1695 2014年10月 [査読有り][通常論文]
   

  Addition of oxides of transition metals such as Mn, Fe, Co, Ni, Cu, and Ce to Pt/Al2O3 catalysts followed by water-pretreatment enhanced its CO oxidation activity. Iron oxide was the most effective promoter between -40 and 150 degrees C among those examined. Below 120 degrees C, CO conversion was maximized at the Fe to Pt molar ratio of 1, whereas above 120 degrees C conversion increased monotonically with Fe content. Pt L-III extended X-ray absorption fine structure analyses suggested that the formation of Pt-Fe alloy enhanced CO oxidation activity at high temperatures but reduced it at low temperatures.
• Heterogeneous Pt Catalysts for Reductive Amination of Levulinic Acid to Pyrrolidones

  Abeda Sultana Touchy, S. M. A. Hakim Siddiki, Kenichi Kon, Ken-ichi Shimizu

  ACS CATALYSIS 4 9 3045 - 3050 2014年09月 [査読有り][通常論文]
   

  Supported platinum catalysts have been studied for the reductive amination of levulinic acid (LA) by H-2 to N-alkyl-5-methyl-2-pyrrolidones under solvent-free conditions. The activity depends on the type of metal (Pt, Re, Pd, Rh, Ru, Cu, Ni), support material, and coloaded oxides of transition metals (V, Cr, Mo, W, Re). In 24 kinds of catalyst tested, Pt and MoOx (molybdenum oxide) coloaded TiO2 (Pt-MoOx/TiO2) shows the highest activity. Pt-MoOx/TiO2 is effective for reductive amination of LA with wide varieties of amines under mild conditions (3 bar of H-2, 100 degrees C, solvent-free) to give high isolated yield of pyrrolidinones and shows higher turnover number (TON) than previously reported catalysts for reductive amination of LA with an aliphatic amine. The catalyst can be separated from the reaction mixture by filtration, and the recovered catalyst can be reused. This is the first general and reusable heterogeneous catalytic system for the reductive amination of LA. On the basis of mechanistic studies, high activity of Pt-MoOx/TiO2 can be attributed to acid-base interaction between the add sites of Pt-MoOx/TiO2 and carboxyl groups in LA and an intermediate.
• N-alkylation of ammonia and amines with alcohols catalyzed by Ni-loaded CaSiO3

  Ken-ichi Shimizu, Shota Kanno, Kenichi Kon, S. M. A. Hakim Siddiki, Hideyuki Tanaka, Yoshihisa Sakata

  CATALYSIS TODAY 232 134 - 138 2014年09月 [査読有り][通常論文]
   

  Nickel nanoparticles loaded onto calcium silicate (Ni/CaSiO3) have been prepared by ion-exchange method followed by in situ H2-reduction of the calcined precursor. Ni/CaSiO3 was found to be effective for the catalytic direct synthesis of primary amines from alcohols and NH3 under relatively mild conditions. Various aliphatic alcohols are tolerated, and the turnover number (TON) was higher than those of Ru-based homogeneous catalysts. The catalyst was recoverable and was reused. Effects of the surface oxidation states and particle size of Ni on the catalytic activity were studied by infrared (IR) investigation of the states of adsorbed CO and transmission electron microscopy (TEM). It is clarified that the surface Ni sites on small (3 nm) sized Ni nanoparticles are the catalytically active species. Ni/CaSiO3 was also effective for the alkylation of anilines and aliphatic amines with various alcohols (benzyl and aliphatic alcohols) under additive free conditions; primary amines were converted into secondary amines and secondary amines into tertiary amines. C) 2013 Elsevier B.V. All rights reserved.
• Hydrogenation of levulinic acid to gamma-valerolactone by Ni and MoOx co-loaded carbon catalysts

  Ken-ichi Shimizu, Shota Kanno, Kenichi Kon

  GREEN CHEMISTRY 16 8 3899 - 3903 2014年08月 [査読有り][通常論文]
   

  To develop a noble metal-free heterogeneous catalyst for liquid phase hydrogenation of levulinic acid to gamma-valerolactone under H-2, we tested a series of base-metal (Ni, Co, Cu, and Fe) and metal oxides (Mo, V. and W oxides) co-loaded carbon (C) and Ni-loaded metal oxides for the reaction. Ni-MoOx/C prereduced at 500 degrees C showed the highest activity and showed more than 300 times higher turnover number (TON) than previously reported noble metal-free catalysts. A structure-activity relationship study showed that the co-presence of metallic Ni-0 species and partially reduced MoO2 could be responsible for the high activity.
• Hydrogenation of levulinic acid to gamma-valerolactone by Ni and MoOx co-loaded carbon catalysts

  Ken-ichi Shimizu, Shota Kanno, Kenichi Kon

  GREEN CHEMISTRY 16 8 3899 - 3903 2014年08月 [査読無し][通常論文]
   

  To develop a noble metal-free heterogeneous catalyst for liquid phase hydrogenation of levulinic acid to gamma-valerolactone under H-2, we tested a series of base-metal (Ni, Co, Cu, and Fe) and metal oxides (Mo, V. and W oxides) co-loaded carbon (C) and Ni-loaded metal oxides for the reaction. Ni-MoOx/C prereduced at 500 degrees C showed the highest activity and showed more than 300 times higher turnover number (TON) than previously reported noble metal-free catalysts. A structure-activity relationship study showed that the co-presence of metallic Ni-0 species and partially reduced MoO2 could be responsible for the high activity.
• Self-Coupling of Secondary Alcohols and alpha-Alkylation of Methyl Ketones with Secondary Alcohols by Pt/CeO2 Catalyst

  Chandan Chaudhari, S. M. A. Hakim Siddiki, Ken-ichi Shimizu

  TOPICS IN CATALYSIS 57 10-13 1042 - 1048 2014年06月 [査読有り][通常論文]
   

  Transition metal-loaded metal oxides are tested for C-C self-coupling of 2-octanol to a higher ketone at 140 degrees C. Among various catalysts, Pt/CeO2 shows the highest activity and shows good reusability. Pt/CeO2 is effective for the self-coupling of various aliphatic secondary alcohols and alpha-alkylation of methyl ketones with aliphatic secondary alcohols. A possible reaction mechanism is discussed.
• Sustainable heterogeneous platinum catalyst for direct methylation of secondary amines by carbon dioxide and hydrogen.

  Kenichi Kon, S M A Hakim Siddiki, Wataru Onodera, Ken-ichi Shimizu

  Chemistry (Weinheim an der Bergstrasse, Germany) 20 21 6264 - 7 2014年05月19日 [査読有り][通常論文]
   

  Pt and MoO(x) co-loaded TiO2 is found to be highly effective for direct methylation of aliphatic and aromatic secondary amines by CO2 and H2 under solvent-free conditions. This is the first additive-free and reusable heterogeneous catalytic system with acceptable turnover number.
• Cooperative H-2 Activation at Ag Cluster/theta-Al2O3(110) Dual Perimeter Sites: A Density Functional Theory Study

  Pussana Hirunsit, Ken-ichi Shimizu, Ryoichi Fukuda, Supawadee Namuangruk, Yoshitada Morikawa, Masahiro Ehara

  JOURNAL OF PHYSICAL CHEMISTRY C 118 15 7996 - 8006 2014年04月 [査読有り][通常論文]
   

  H-2 dissociation by Ag clusters supported on the theta-Al2O3(110) surface has been investigated using density functional theory calculations. The crucial role of the dual perimeter site of Ag cluster and the surface oxygen (0) site of the alumina support is demonstrated with three theoretical models: anchored cluster, isolated cluster, and anchored cluster on hydroxylated alumina. The heterolytic cleavage of H-2 at the silver-alumina interface, yielding Ag-H-delta- and O-H delta+, is thermodynamically and kinetically preferred compared with H-2 cleavage at two Ag atomic sites on top of the Al2O3-supported Ag cluster and the homolytic cleavage of H-2 on the isolated Ag cluster. The hydroxylation at the O site of the alumina reduces the H-2 dissociation activity, which indicates that the interfacial bare O site is indispensible. It is concluded that the interfacial cooperative mechanism between the Ag cluster and Lewis acid-base pair site (bare Al-O site) is essentially relevant for the H-2 activation over Ag-loaded, Al2O3 catalysts.
• Fe3+-exchanged clay catalyzed transamidation of amides with amines under solvent-free condition

  Md. Ayub Ali, S. M. A. Hakim Siddiki, Kenichi Kon, Ken-ichi Shimizu

  TETRAHEDRON LETTERS 55 7 1316 - 1319 2014年02月 [査読有り][通常論文]
   

  Fe3+-exchanged montmorillonite is shown to be an effective and reusable heterogeneous catalyst for the transamidation of various amides and amines under solvent-free condition. The catalyst shows high yields and wide substrate scope. (C) 2014 Elsevier Ltd. All rights reserved.
• Versatile and sustainable alcoholysis of amides by a reusable CeO2 catalyst

  S. M. A. Hakim Siddiki, Abeda Sultana Touchy, Masazumi Tamura, Ken-ichi Shimizu

  RSC ADVANCES 4 67 35803 - 35807 2014年 [査読有り][通常論文]
   

  CeO2 catalyzed the esterification between an equivalent molar ratio of primary amides and alcohols under neutral conditions, which provides the first versatile reusable catalytic system for direct alcoholysis of amides to esters with wider scope and 67 times higher turnover number (TON) than previous catalytic systems.
• Selective hydrogenation of levulinic acid to valeric acid and valeric biofuels by a Pt/HMFI catalyst

  Kenichi Kon, Wataru Onodera, Ken-ichi Shimizu

  CATALYSIS SCIENCE & TECHNOLOGY 4 9 3227 - 3234 2014年 [査読有り][通常論文]
   

  We describe one-pot high-yield catalytic pathways for the conversion of levulinic acid (LA) to valeric acid (VA) or valeric acid esters (so-called valeric biofuels) under relatively mild conditions (2 or 8 bar H-2, 200 degrees C). A thorough screening study reveals that a HMFI zeolite-supported Pt metal cluster (Pt/HMFI) with an average cluster size of 1.9 nm shows the highest yield of VA (99%) under solvent-free conditions. The use of ethanol or methanol as solvent changes the selectivity, resulting in 81-84% yields of ethyl valerate (EV) or methyl valerate (MV). Pt/HMFI is also effective for selective formation of valeric acid esters from gamma VL in alcohols under H-2. Kinetics, in situ infrared (IR), and acidity-activity relationship studies show a cooperative mechanism of Pt and Bronsted acid sites of HMFI. VA formation from LA can be driven by Pt-catalyzed hydrogenation of LA to gamma VL, which undergoes proton-assisted ring-opening by HMFI, followed by Pt-catalyzed hydrogenation. Valeric ester formation from LA is driven by esterification of LA to levulinic ester, which is hydrogenated by Pt.
• Hydrodeoxygenation of fatty acids and triglycerides by Pt-loaded Nb2O5 catalysts

  Kenichi Kon, Wataru Onodera, Satoru Takakusagi, Ken-ichi Shimizu

  CATALYSIS SCIENCE & TECHNOLOGY 4 10 3705 - 3712 2014年 [査読有り][通常論文]
   

  Platinum nanoparticles loaded onto various supports have been studied for the selective hydrogenation of lauric acid to n-dodecane. The activity depends on the support material and pre-reduction temperature. Pt/Nb2O5 reduced at 300 degrees C gives the highest activity. Pt/Nb2O5 shows higher activity than various Nb2O5-supported transition metals (Ir, Re, Ru, Pd, Cu, Ni). Under solvent-free conditions Pt/Nb2O5 is effective for the hydrodeoxygenation of lauric, capric, palmitic, myristic, oleic, and stearic acids under 8 bar H-2 at 180-250 degrees C, which gives high yields (88-100%) of linear alkanes with the same chain length as the starting compound. Tristearin is also converted to give 93% yield of n-octadecane. Pt/Nb2O5 shows more than 60 times higher turnover number (TON) than the previously reported catalysts for the hydrogenation of stearic acid to n-octadecane. Mechanistic study shows a consecutive reaction pathway in which lauric acid is hydrogenated to 1-dodecanol, which undergoes esterification with lauric acid as well as hydrogenation to n-dodecane. The ester undergoes hydrogenolysis to give the alcohol, which is hydrogenated to the alkane. Infrared (IR) study of acetic acid adsorption on Nb2O5 indicates that Lewis acid-base interaction of Nb cation and carbonyl oxygen, which suggests a possible role of Nb2O5 as an activation site of carbonyl groups during hydrodeoxygenation.
• Direct synthesis of quinazolinones by acceptorless dehydrogenative coupling of o-aminobenzamide and alcohols by heterogeneous Pt catalysts

  S. M. A. Hakim Siddiki, Kenichi Kon, Abeda Sultana Touchy, Ken-ichi Shimizu

  CATALYSIS SCIENCE & TECHNOLOGY 4 6 1716 - 1719 2014年 [査読有り][通常論文]
   

  HBEA zeolite-supported Pt metal nanoclusters (Pt/HBEA) effectively catalyze direct dehydrogenative synthesis of quinazolinones from o-aminobenzamide and alcohols under promoter-free conditions. This is the first heterogeneous catalytic system for this reaction, which has a turnover number (TON) more than 25 times higher than previous homogeneous catalysts as well as wide scope for aliphatic and aromatic alcohols.
• C-3 alkylation of oxindole with alcohols by Pt/CeO2 catalyst in additive-free conditions

  Chandan Chaudhari, S. M. A. Hakim Siddiki, Kenichi Kon, Atsuko Tomita, Yutaka Tai, Ken-ichi Shimizu

  CATALYSIS SCIENCE & TECHNOLOGY 4 4 1064 - 1069 2014年 [査読有り][通常論文]
   

  In a series of transition metal-loaded CeO2 catalysts and Pt-loaded catalysts on various supports, Pt-loaded CeO2 shows the highest activity for the selective C-3 alkylation of oxindole with octanol. The catalyst is effective for alkylation of oxindole and N-substituted oxindole with a series of substituted benzyl, linear, hetero-aryl alcohols under additive-free conditions and is recyclable. Our results demonstrate the first additive-free catalytic system for this reaction. Mechanistic studies show that this system is driven by the borrowing-hydrogen pathway. Structure-activity relationship studies show that co-presence of surface Pt-0 species on Pt metal clusters and basic support is indispensable for this catalytic system.
• Acceptorless dehydrogenative synthesis of 2-substituted quinazolines from 2-aminobenzylamine with primary alcohols or aldehydes by heterogeneous Pt catalysts

  Chandan Chaudhari, S. M. A. Hakim Siddiki, Masazumi Tamura, Ken-ichi Shimizu

  RSC ADVANCES 4 95 53374 - 53379 2014年 [査読有り][通常論文]
   

  CeO2-supported Pt nanoparticle catalysts enabled the acceptorless dehydrogenative synthesis of 2-substituted quinazolines from 2-aminobenzylamine with aliphatic and benzyl primary alcohols or aldehydes with low catalyst loading, wide substrate scope and good catalyst reusability, demonstrating the first acceptor-free and additive-free catalytic system for this reaction.
• Acceptorless dehydrogenative coupling of primary alcohols to esters by heterogeneous Pt catalysts

  Sondomoyee Konika Moromi, S. M. A. Hakim Siddiki, Md. Ayub Ali, Kenichi Kon, Ken-ichi Shimizu

  CATALYSIS SCIENCE & TECHNOLOGY 4 10 3631 - 3635 2014年 [査読有り][通常論文]
   

  Supported platinum catalysts have been studied for the acceptor-free dehydrogenative coupling of primary alcohols to esters in the liquid phase under solvent-free conditions in N-2 at 180 degrees C. The activity depends on the support material, and Pt-loaded SnO2 (Pt/SnO2) gives the highest activity. Pt/SnO2 shows higher activity than various transition metals (Ir, Re, Ru, Rh, Pd, Ag, Co, Ni, Cu) loaded on SnO2. The Pt/SnO2 catalyst (1 mol%) selectively converted various primary alcohols to their corresponding esters in moderate to high isolated yield (53-91%). This is the first example of reusable heterogeneous catalysts for the acceptor-free dehydrogenative coupling of primary alcohols to esters under additive-free and solvent-free conditions. Mechanistic and infrared (IR) studies are also shown to discuss the reaction pathway and a possible role of the SnO2 support as Lewis acid sites that activate carbonyl groups of adsorbed aldehyde intermediates.
• Oxygen reduction reaction over silver particles with various morphologies and surface chemical states

  Junya Ohyama, Yui Okata, Noriyuki Watabe, Makoto Katagiri, Ayaka Nakamura, Hidekazu Arikawa, Ken-ichi Shimizu, Tatsuya Takeguchi, Wataru Ueda, Atsushi Satsuma

  JOURNAL OF POWER SOURCES 245 998 - 1004 2014年01月 [査読有り][通常論文]
   

  The oxygen reduction reaction (ORR) in an alkaline solution was carried out using Ag powders having various particle morphologies and surface chemical states (Size: ca. 40-110 nm in crystalline size. Shape: spherical, worm like, and angular. Surface: smooth with easily reduced AgOx, defective with AgOx, and Ag2CO3 surface layer). The various Ag powders were well characterized by X-ray diffraction, X-ray photoelectron spectroscopy, N-2 adsorption, scanning electron microscopy, Raman spectroscopy, cyclic voltammetry, and stripping voltammetry of underpotential-deposited lead. Defective and oxidized surfaces enhanced the Ag active surface area during the ORR. The ORR activity was affected by the morphology and surface chemical state: Ag particles with defective and angular surfaces showed smaller electron exchange number between three and four but showed higher specific activity compared to Ag particles with smooth surfaces. (C) 2013 Elsevier B.V. All rights reserved.
• Oxidation of silanes to silanols on Pd nanoparticles: H2 desorption accelerated by surface oxygen atom

  Takashi Kamachi, Ken-Ichi Shimizu, Daisuke Yoshihiro, Kazunobu Igawa, Katsuhiko Tomooka, Kazunari Yoshizawa

  Journal of Physical Chemistry C 117 44 22967 - 22973 2013年11月07日 [査読有り][通常論文]
   

  The oxidation of silane to silanol on the clean and oxygen-covered Pd(111) surface is investigated with periodic density functional theory calculations to gain a better understanding of the effect of surface oxygen atom on Pd nanoparticle catalysts. The calculations confirmed that this catalytic reaction is initiated by the dissociative adsorption of silane on the Pd surface. The resultant silyl group is attacked by a water molecule to form silanol and an H atom on the Pd surface with inversion of configuration at the Si center. An activation energy of 11.3 kcal/mol is required for the water addition, and the transition state for this step is energetically highest in the entire reaction profile. These computational results are in good agreement with our stereochemical and kinetic studies. The H atoms on the Pd surface inhibit further reaction, and therefore, they should be removed to achieve the catalytic activity experimentally. We found that the role of the surface oxygen atom is to facilitate the desorption of H2 from the Pd surface without the formation of OH and H2O. The introduction of surface oxygen atoms can enhance the catalytic ability of metal nanoparticles for green organic reactions. © 2013 American Chemical Society.
• Alkylation of 2-methylquinoline with alcohols under additive-free conditions by Al2O3-supported Pt catalyst

  Chandan Chaudhari, S. M. A. Hakim Siddiki, Ken-ichi Shimizu

  TETRAHEDRON LETTERS 54 48 6490 - 6493 2013年11月 [査読有り][通常論文]
   

  Supported metal nanoparticle catalysts are studied for alkylation of 2-methylquinoline with benzyl alcohol under additive-free conditions in N-2 atmosphere. Among various metal-loaded Al2O3 catalysts and supported Pt catalysts, Pt metal nanocluster loaded-Al2O3 pre-reduced in H-2 at 500 degrees C shows highest yield (82%) of the product (2-phenethyl-quinoline). The catalyst is reusable, shows higher turnover number than a previous homogeneous catalyst, and shows good to moderate yield for alkylation of 2-methylquinoline with various alcohols. The reaction is driven by the borrowing-hydrogen pathway, in which aldehyde formed by dehydrogenation of alcohol undergoes aldol condensation with 2-methylquinoline to give the alkene intermediate which is finally hydrogenated by Pt-H species. (C) 2013 Elsevier Ltd. All rights reserved.
• General and selective C-3 alkylation of indoles with primary alcohols by a reusable Pt nanocluster catalyst

  S. M. A. Hakim Siddiki, Kenichi Kon, Ken-Ichi Shimizu

  Chemistry - A European Journal 19 43 14416 - 14419 2013年10月18日 [査読有り][通常論文]
   

  The platinum rule: Heterogeneous, additive-free C-3 selective alkylation of indoles by aliphatic and aromatic alcohols proceeded under transfer hydrogenation conditions with the reusable Pt/θ-Al2O 3 catalyst (see scheme TON=turnover number). Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
• Formal Synthesis of (+)-Madindoline A, a Potent IL-6 Inhibitor, Utilizing Enzymatic Discrimination of Quaternary Carbon

  Ken-ichi Shimizu, Mina Tomita, Ken-ichi Fuhshuku, Takeshi Sugai, Mitsuru Shoji

  NATURAL PRODUCT COMMUNICATIONS 8 7 897 - 901 2013年07月 [査読有り][通常論文]
   

  A formal synthesis of (+)-madindoline A was achieved. The Sunazuka's key intermediate, (4R,5S)-(-)-3-butyl-4-(tert-butyldimethylsiloxy)-5-methoxycarbonyl-2,5-dimethyl-2-cyclopentenone, was synthesized from easily available (2S,38)-3-acetoxy-2-ethenyl-2-methylcyclopentanone. The starting material was reliably supplied by a chemo-enzymatic procedure in enantiomerically pure form. The synthesis was performed by straightforward transformations involving enone formation and regioselective introduction of the two alkyl side chains.
• ものづくりライセンス技術の実用化 担持Niナノ粒子触媒を用いた環境調和型有機合成

  清水研一

  ケミカルエンジニヤリング 58 7 494 - 498 化学工業社 2013年07月01日 [査読無し][通常論文]
  
• Self-coupling of secondary alcohols by Ni/CeO2 catalyst

  Katsuya Shimura, Kenichi Kon, S. M. A. Hakim Siddiki, Ken-ichi Shimizu

  APPLIED CATALYSIS A-GENERAL 462 137 - 142 2013年07月 [査読有り][通常論文]
   

  Supported nickel catalysts are studied for the liquid phase C-C self-coupling of aliphatic secondary alcohols under additive free conditions in N-2 atmosphere. Among various Ni catalysts, 1 or 3 wt% Ni/CeO2 catalysts pre-reduced in H-2 shows highest yield (94%) of a dimer product (a higher ketone) for the self-coupling of 1-octanol at 130 degrees C, and the catalyst is reused. The catalysts are also effective for self-coupling of various secondary alcohols, providing the first heterogeneous catalytic system for the self-coupling of secondary alcohols under mild conditions. Effects of support material and oxidation state of Ni on the activity are studied and it is found that both CeO2 and metallic Ni are indispensable for the reaction. A possible reaction mechanism is proposed, in which ketones, formed by dehydrogenation of alcohol, undergone Aldol condensation to give alpha,beta-unsaturated ketone which is finally hydrogenated by in situ formed Ni-H species. (C) 2013 Elsevier B.V. All rights reserved.
• Heterogeneous Ni Catalysts for N-Alkylation of Amines with Alcohols

  Ken-ichi Shimizu, Naomichi Imaiida, Kenichi Kon, S. M. A. Hakim Siddiki, Atsushi Satsuma

  ACS CATALYSIS 3 5 998 - 1005 2013年05月 [査読有り][通常論文]
   

  Nickel nanoparticles loaded onto various supports (Ni/MOx) have been prepared and studied for the N-alkylation of amines with alcohols. Among the catalysts, Ni/theta-Al2O3 prepared by in situ H-2-reduction of Ni/theta-Al2O3 shows the highest activity, and it acts as reusable heterogeneous catalyst for the alkylation of anilines and aliphatic amines with Various alcohols (benzyl and aliphatic alcohols) under additive free conditions. Primary amines are converted into secondary amines and secondary amines into tertiary amines. For the reaction of with, an aliphatic alcohol the catalyst shows higher turnover number (TON) than precious metal-based state-of-the-art catalysts. Mechanistic studies suggest that the reaction proceeds through hydrogen-borrowing mechanism. The activity of Ni catalysts depends on the nature of support materials; acid-base bifunctional supports give higher activity than basic or acidic supports, indicating that acid-base sites on supports are necessary. The presence of basic (pyridine) or acidic (acetic acid) additive in the solution decreased the activity of Ni/theta-Al2O3, which suggests the cooperation of the acid base site of theta-Al2O3. For a series of Ni/theta-Al2O3 catalysis with different particle size, the turnover frequency, (TOF) per surface Ni increases with decreasing Ni mean particle size, inclicating that low-coordinated Ni species and/or metal-support interface are active sites. From these results, we propose that the site for this reaction is metal-support interface, where low-coordinated. atoms adjacent to the acid-base sites of alumina.
• Acceptor-free dehydrogenation of secondary alcohols by heterogeneous cooperative catalysis between Ni nanoparticles and acid-base sites of alumina supports

  Ken-ichi Shimizu, Kenichi Kon, Katsuya Shimura, Siddiki S. M. A. Hakim

  JOURNAL OF CATALYSIS 300 242 - 250 2013年04月 [査読有り][通常論文]
   

  Nickel-nanoparticle-loaded theta-Al2O3 (Ni/theta-Al2O3), prepared by H-2-reduction of NiO/theta-Al2O3, acts as an effective and reusable heterogeneous catalyst for acceptor-free dehydrogenation of alcohols in a liquid phase. Among various supports, amphoteric supports (such as theta-Al2O3), having both acidic and basic sites, gave higher activity than acidic or basic supports. Among Ni/theta-Al2O3 catalysts with different Ni particle sizes, turnover frequency (TOF) per surface Ni increases with decreasing Ni particle size. These results suggest that low-coordinated Ni-0 sites and metal/support interfaces play important roles in the catalytic cycle. The reaction mechanism is investigated by in situ IR study combined with kinetic analysis (kinetic isotope effect), and the following mechanism is proposed: (1) reaction of an alcohol with Lewis acid (Al delta+)-base (Al-O delta-) pair site of alumina yields an alkoxide on the Al delta+ site and a proton on the Al-O delta- site, (2) C-H dissociation of the alkoxide by Ni-0 site to form Ni-H and a ketone, and (3) protolysis of Ni-H by a neighboring proton to release H-2 gas. The proposed mechanism provides fundamental reasons for the higher activity of Ni on the acid-base bifunctional support (Al2O3) than on basic and acidic ones. (C) 2013 Elsevier Inc. All rights reserved.
• Oxidation of CO over Ru/Ceria prepared by self-dispersion of Ru metal powder into nano-sized particle

  Atsushi Satsuma, Masatoshi Yanagihara, Junya Ohyama, Kenichi Shimizu

  CATALYSIS TODAY 201 62 - 67 2013年03月 [査読有り][通常論文]
   

  The oxidation of CO was performed using physical mixture of Ru metal powder and various metal oxide supports after calcination in air and reduction in H-2. Among various supports (CeO2, ZrO2, MgO, Al2O3, TiO2, SnO2,and SiO2), only Ru + CeO2 showed very high catalytic activity for CO oxidation with the light-off temperature below 100 degrees C, which was comparable to Ru/CeO2 prepared by a conventional impregnation method. The optimum conditions for the preparation were loading amount of 2 wt%, calcination at 700 degrees C in air followed by reduction at 400 degrees C in 5% H-2. It was revealed that the high catalytic activity for Ru + CeO2 is attributed to the high dispersion of Ru on CeO2. The original Ru metal powder having diameter of 36 nm was dispersed during the calcination leading into small Ru particles having diameter around 2 nm. Raman spectra indicated that the formation of Ru-O-Ce bond after the calcination is one of the key for the Ru dispersion. The self-dispersion of Ru was not achieved by the calcination in N-2. It was proposed that the self-dispersion of Ru into nano-particles was caused by oxidation of Ru metal into Ru oxide in air, then dispersion of nano-sized Ru oxide by forming Ru-O-Ce bond, and finally conversion of Ru oxide particles into nano-sized Ru metal particles in a flow of H-2. (C) 2012 Elsevier B. V. All rights reserved.
• Activity controlling factors for low-temperature oxidation of CO over supported Pd catalysts

  Atsushi Satsuma, Kaoru Osaki, Masatoshi Yanagihara, Junya Ohyama, Kenichi Shimizu

  APPLIED CATALYSIS B-ENVIRONMENTAL 132 511 - 518 2013年03月 [査読有り][通常論文]
   

  The effect of supports (ceO(2), TiO2, Al2O3, ZrO2, and SiO2) on CO oxidation over Pd catalysts at low temperatures was investigated, and activity-controlling factors were discussed. The light-off temperature was in the order of Pd/CeO2 < Pd/TiO2 < Pd/Al2O3 < Pd/ZrO2 < Pd/SiO2 which was fairly in agreement with the reduction temperature of supported Pd to metallic species in CO-Temperature programmed reduction (CO-TPR) profile. The result indicates that higher reducibility of supported Pd to metallic species is one of the activity-controlling factors for the oxidation activity. The activation of oxygen on metal oxide support is suggested to be another factor for the low temperature oxidation. Actually, in situ IR measurement revealed that the oxidation of CO proceeds on Pd/CeO2 and Pd/TiO2 even under nearly 100% coverage of CO over Pd, though Pd/Al2O3 showed CO oxidation activity below 50% coverage of CO. The supports having oxygen storage property, CeO2 and TiO2, contribute to the oxygen activation to proceed CO oxidation irrespective of self-poisoning of metallic Pd surface by adsorbed CO. It was concluded that both of the following two factors are essential for CO oxidation at low temperature: (1) formation of metallic Pd and (2) oxygen storage property of metal oxide support. (C) 2012 Elsevier B.V. All rights reserved.
• Observation of the orientation of membrane protein crystals grown in high magnetic force fields

  Nobutaka Numoto, Ken-ichi Shimizu, Kazuya Matsumoto, Kunio Miki, Akiko Kita

  JOURNAL OF CRYSTAL GROWTH 367 53 - 56 2013年03月 [査読有り][通常論文]
   

  Crystallization of membrane proteins in magnetic fields is thought to reveal the magnetic orientations of crystals, and is expected to enhance crystal quality for X-ray crystallographic analysis. The light-harvesting complex 2 (LH2) from a photosynthetic bacterium, Thermochromatium tepidum was crystallized in steep-gradient magnetic fields. The rod-shaped crystals of LH2 grown in the magnetic fields were oriented parallel to the magnetic field direction. An X-ray diffraction experiment indicated that the overall R value and crystal mosaicity are improved for the magnetically oriented crystal, and the helix bundles of LH2 were located parallel to the magnetic field direction in the crystal packing. (C) 2013 Elsevier B.V. All rights reserved.
• Heterogeneous Ni Catalyst for Direct Synthesis of Primary Amines from Alcohols and Ammonia

  Ken-ichi Shimizu, Kenichi Kon, Wataru Onodera, Hiroshi Yamazaki, Junko N. Kondo

  ACS CATALYSIS 3 1 112 - 117 2013年01月 [査読有り][通常論文]
   

  This paper reports the synthesis of primary amines from alcohols and NH3 by an Al2O3-supported Ni nanoparticle catalyst as the first example of heterogeneous and noble-metal-free catalytic system for this reaction without additional hydrogen sources under relatively mild conditions. Various aliphatic alcohols are tolerated, and turnover numbers were higher than those of Ru-based homogeneous catalysts. The catalyst was recoverable and was reused. The effects of the Ni oxidation states and the acid-base nature of support oxides on the catalytic activity are studied. It is clarified that the surface metallic Ni sites are the catalytically active species, and the copresence of acidic and basic sites on the support surface is also indispensable for this catalytic system.
• Mechanism of Low-Temperature CO Oxidation on Pt/Fe-Containing Alumina Catalysts Pretreated with Water

  Atsuko Tomita, Ken-ichi Shimizu, Kazuo Kato, Tomoki Akita, Yutaka Tai

  JOURNAL OF PHYSICAL CHEMISTRY C 117 3 1268 - 1277 2013年01月 [査読有り][通常論文]
   

  In a previous article (Catal. Commun. 2012, 17, 194), we reported that Pt/Fe-containing alumina catalysts pretreated with water could catalyze CO oxidation even below room temperature. To clarify the effect of the water pretreatment and the reaction mechanism of the novel catalytic system, in situ Fourier transform infrared (FT-IR), and X-ray absorption fine structure (XAFS) measurements during CO oxidation were conducted. From FT-IR measurements, it was revealed that the Pt surface of the catalyst was covered with CO and that the adsorbed CO molecules did not desorb easily, as in the case of conventional Pt/Al2O3 catalyst. Pt L-III XAFS results also suggested the presence of CO on the Pt surface during CO oxidation. Thresholds of Fe K X-ray absorption near-edge structure shifted with the change between oxidative (0.5% O-2/He) and reductive (1% CO/He) atmospheres, indicating that the Fe redox change Fe2+ <-> Fe3+ can participate in the reaction. From the degree of the shifts and average Pt diameters derived from high-angle annular dark-field scanning transmission electron microscopy and metal dispersion measurements, it was concluded that PtNP/FeOx boundaries were efficiently formed upon the water pretreatment. The enhanced reactivity of the water-pretreated catalyst can be attributed to the increased number of boundaries and Pt diameter.
• Heterogeneous cobalt catalysts for the acceptorless dehydrogenation of alcohols

  Ken-Ichi Shimizu, Kenichi Kon, Mayumi Seto, Katsuya Shimura, Hiroshi Yamazaki, Junko N. Kondo

  Green Chemistry 15 2 418 - 424 2013年 [査読有り][通常論文]
   

  A series of transition metal(M)-loaded TiO< inf> 2< /inf> catalysts (M/TiO< inf> 2< /inf> ) and Co-loaded catalysts on various support materials were prepared by an impregnation method, followed by in situ H< inf> 2< /inf> -reduction at 400 °C, and tested for the acceptor-free oxidation of cyclododecanol in the liquid phase. Among the catalysts including noble metal catalysts, Co/TiO< inf> 2< /inf> showed the highest activity. In the presence of Co/TiO < inf> 2< /inf> (0.1-3 mol%) the dehydrogenation of various aliphatic secondary alcohols proceeded to afford the corresponding ketones. The catalyst was recoverable and was reused after the H< inf> 2< /inf> -reduction treatment. Based on the spectroscopic characterization of the catalyst combined with the studies on the effect of the Co oxidation states on the catalytic activity, it is clarified that the surface metallic Co sites with electron deficiency are the catalytically active species. © 2013 The Royal Society of Chemistry.
• CeO2-catalyzed nitrile hydration to amide: reaction mechanism and active sites

  Masazumi Tamura, Atsushi Satsuma, Ken-ichi Shimizu

  CATALYSIS SCIENCE & TECHNOLOGY 3 5 1386 - 1393 2013年 [査読有り][通常論文]
   

  CeO2 acted as a reusable and effective catalyst for the hydration of various nitriles to amides in water, under neutral conditions at low temperature (30-100 degrees C). To identify the active site, we examined the relationship between activity and the amount of the pair site of a low-coordinated Ce site (Ce-LC) (oxygen defect site) and adjacent Lewis base (exposed oxygen), determined by methanol adsorption on FTIR. It is revealed that the Ce-LC-O site is the active site for the reaction. To clarify the reaction mechanism, we carried out in situ FTIR studies on the reaction of acetonitrile with surface Ce-OH groups and kinetic studies such as H2O/D2O kinetic isotope effect and Hammett plot. The results give the following catalytic cycle: (1) dissociation of H2O on the Ce-LC-O site (oxygen defect site) to give OH delta- and H delta+ species on the site, (2) formation of an adsorption complex between nitrile and CeO2, (3) addition of OH delta- to the carbon atom of the cyano group of the complex and (4) desorption of the amide from the CeO2 surface, accompanying a regeneration of the Ce-LC-O site. On the basis of the above fundamental information, we found a simple method for activity increase; preheating of CeO2 at 600 degrees C resulted in desorption of surface carbonate, and the exposed Ce-LC-O site thus prepared showed one order of magnitude higher activity for the hydration of various nitriles than untreated CeO2.
• レアメタル代替・低減に関する技術開発 銀クラスター触媒による環境調和型有機合成

  清水研一

  ペトロテック 36 1 12-16,48  2013年01月01日 [査読無し][通常論文]
  
• CeO2 as a versatile and reusable catalyst for transesterification of esters with alcohols under solvent-free conditions

  Masazumi Tamura, S. M. A. Hakim Siddiki, Ken-ichi Shimizu

  GREEN CHEMISTRY 15 6 1641 - 1646 2013年 [査読有り][通常論文]
   

  CeO2 acted as an efficient and reusable heterogeneous catalyst for transesterification of esters with alcohols under the solvent-free conditions at 160 degrees C. Among the 11 kinds of metal oxides, CeO2 is the most suitable catalyst in terms of catalytic activity, leaching-resistance and reusability. This catalytic system tolerates various esters and alcohols, and valuable esters such as heteroaromatic esters and benzyl benzoates are produced, demonstrating a practical utility of the system. On the basis of kinetic analysis and in situ IR studies of adsorbed species, a reaction mechanism is proposed, in which proton abstraction of alcohol by a Lewis base site of CeO2 to yield alkoxide species is the rate-limiting step.
• Size- and support-dependent Pt nanocluster catalysis for oxidant-free dehydrogenation of alcohols

  Kenichi Kon, S. M A Hakim Siddiki, Ken-Ichi Shimizu

  Journal of Catalysis 304 63 - 71 2013年 [査読有り][通常論文]
   

  Pt nanocluster-loaded metal oxides, in situ pre-reduced under H2 at 500 C, were tested for the dehydrogenation of aliphatic secondary alcohols in the liquid phase. The activity for dehydrogenation of 2-octanol depended strongly on the acid-base character of the support oxide, and amphoteric oxides, especially γ-Al2O3, gave high activity. For a series of Pt/Al2O3 catalysts with different Pt particle size, the turnover frequency (TOF) per surface Pt increases with decreasing Pt particle size, suggesting that low-coordinated Pt sites and metal/support interface play important roles in the catalytic cycle. The most active catalyst, Pt/Al2O3 with Pt particle size of 1.4 nm, acted as reusable heterogeneous catalyst for dehydrogenation of aliphatic secondary alcohols to afford corresponding ketones. Pt/Al2O3 showed higher activity than other M/Al2O3 (Co, Ni, Cu, Ru, Rh, Pd, Ag, Re, Ir, Au) catalysts and showed two orders of magnitude higher turnover number (TON) than previously reported Pt catalysts for alcohol oxidation. On the basis of the mechanistic studies by in situ infrared (IR) and kinetic experiments, the following cooperative mechanism is proposed: (1) reaction of an alcohol with Lewis acid (Alδ+)-base (AlOδ-) pair site of alumina yields an alkoxide on the Alδ+ site and a proton on the AlOδ- site, (2) CH dissociation of the alkoxide by Pt0 site to form PtH and a ketone, (3) protolysis of PtH by a neighboring proton to release H2 gas. The mechanism provides fundamental reasons for the higher activity of Pt on the acid-base bifunctional support (Al2O3) than those on basic and acidic one. © 2013 Elsevier Inc. All rights reserved.
• Heterogeneous nickel catalyst for selective hydration of silanes to silanols

  Ken-ichi Shimizu, Katsuya Shimura, Naomichi Imaiida, Atsushi Satsuma

  JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL 365 50 - 54 2012年12月 [査読有り][通常論文]
   

  Selective catalytic hydration of silanes to silanols is studied by Ni metal nanoparticles (NPs) on activated carbon (Ni/C) prepared by in situ H-2-reduction of NiO-loaded activated carbon (NiO/C). The catalytic activity of Ni/C increases with decrease in the average Ni particle size. Ni/C with the smallest size (7.6 nm) exhibits a high selectivity for silanols, high turnover number (TON) of 9300, and excellent reusability. Studies on the structure-activity relationship show that metallic Ni species on the surface of small Ni metal particles are catalytically active species. Based on mechanistic studies, a catalytic cycle involving the activation of Et3SiH as the rate limiting step is proposed. (C) 2012 Elsevier B.V. All rights reserved.
• Surface Oxygen Atom as a Cooperative Ligand in Pd Nanoparticle Catalysis for Selective Hydration of Nitriles to Amides in Water: Experimental and Theoretical Studies

  Ken-ichi Shimizu, Takahiro Kubo, Atsushi Satsuma, Takashi Kamachi, Kazunari Yoshizawa

  ACS CATALYSIS 2 12 2467 - 2474 2012年12月 [査読有り][通常論文]
   

  On the basis of an insight in surface science that Pd surfaces partially covered with oxygen adatoms (O-ad) show higher reactivity for water dissociation than clean Pd surfaces, we studied the effect of O-ad on the activity of carbon-supported palladium metal nanoparticle catalysts (Pd/C) for the selective hydration of nitriles to amides in water. A series of Pd/C with the same Pd loading (5 wt %) and a similar particle size (5.3-6.5 nm) but with different surface coverage of O-ad were prepared and characterized by various spectroscopic methods. The freshly H-2-reduced Pd/C shows no catalytic activity for hydration of acetonitrile, indicating that clean Pd metal surfaces are inactive. Air exposure of this catalyst under ambient conditions results in the formation of Pd metal NPs partially covered with O-ad, which act as effective and recyclable heterogeneous catalysts for selective hydration of various nitriles to the corresponding amides. Theoretical studies based on density functional theory calculations clarified a cooperative mechanism between metallic Pd and O-ad, in which O-ad as a Bronsted base site plays an important role in the dissociation of water via hydrogen bonding, and the mechanism is verified by kinetic results (activation energy, H2O/D2O kinetic isotope effect, Hammett slope). The mechanistic finding demonstrates a new design strategy of metal nanoparticle catalysts based on a molecular-level understanding of catalysis on oxygen-adsorbed metal surfaces.
• CeO2-catalyzed Transformations of Nitriles and Amides

  Masazumi Tamura, Ken-ichi Shimizu, Atsushi Satsuma

  CHEMISTRY LETTERS 41 11 1397 - 1405 2012年11月 [査読有り][招待有り]
   

  Recently, cerium oxides have been extensively used as heterogeneous catalysts for green organic reactions. This review describes recent progress in such reactions, with a focus on our studies on pure CeO2-catalyzed reactions of nitrites and amides with nucleophiles (H2O, alcohols, and amines). Hydration of nitrites to amides in water, one-pot ester synthesis from nitrites and alcohols, one-pot synthesis of N-alkylamides from nitrites with amines, and synthesis of N-alkylamides from amides and amines (transamidation) are selectively catalyzed by CeO2 under aqueous or solvent-free conditions. Mechanistic studies suggest that a cooperation of Lewis acid site (Ce4+ cation) and acid-base (Ce-O) pair site plays essential roles in the catalytic reactions.
• Volcano-Curves for Dehydrogenation of 2-Propanol and Hydrogenation of Nitrobenzene by SiO2-Supported Metal Nanoparticles Catalysts As Described in Terms of a d-Band Model

  Masazumi Tamura, Kenichi Kon, Atsushi Satsuma, Ken-ichi Shimizu

  ACS CATALYSIS 2 9 1904 - 1909 2012年09月 [査読有り][通常論文]
   

  To confirm whether the activity trends in multistep organic reactions can be understood in terms of the Hammer-Norskov d-band model in combination with the linear energy relations, we studied correlations between the reaction rates for dehydrogenation and hydrogenation reactions and the position of the d-band center (epsilon(d)) relative to the Fermi energy (E-F), the epsilon(d) - E-F value, of various metal catalysts. SiO2-supported metal (M = Ag, Cu, Pt, Ir, Pd, Rh, Ru, Ni, and Co) catalysts with the same metal loading (5 wt %) and similar metal particle size (8.9-11.7 nm) were prepared. The dehydrogenation of adsorbed 2-propanol in a flow of He and the hydrogenation of adsorbed nitrobenzene in a flow of H-2 were tested as model reactions of organic reactions on the metal surface. As a test reaction of H-2 dissociation on the surface, SiOH/SiOD exchange on the M/SiO2 catalysts in a flow of D-2 is carried out. The liquid phase hydrogenation of nitrobenzene under 3.0 MPa of H-2 is adopted as an organic reaction under realistic conditions. Generally, the activities show volcano-type dependences on the epsilon(d) - E-F value, indicating that the epsilon(d) - E-F value is useful as a qualitative activity descriptor in heterogeneous catalysis of metal nanoparticles for multistep organic reactions.
• Comprehensive IR study on acid/base properties of metal oxides

  Masazumi Tamura, Ken-ichi Shimizu, Atsushi Satsuma

  APPLIED CATALYSIS A-GENERAL 433 135 - 145 2012年08月 [査読有り][通常論文]
   

  Acid/base properties (type, strength, number) of a wide range of metal oxides were studied by IR (infrared) spectroscopy. Ammonia, pyridine and CD3CN were used as probe molecules for acidity measurement. CO2, CHCl3, benzaldehyde and nitrobenzene were used for basicity measurement. Pyridine for the nature and number of acid sites. CD3CN for the strength of acid sites, CHCl3 for the strength of basic sites and nitrobenzene for the number of basic sites were found to be suitable probes. The absorption coefficients of pyridine for acidic sites and nitrobenzene for basic sites, estimated for various metal oxides by IR coupled with mass spectrometry, were within +/- 10% of the average value, which indicates that the integrated molar extinction coefficients could be used for semi-quantification of acid/base sites of various oxides samples. The comprehensive IR results in this study will be available to characterize properties of Lewis and Bronsted acid sites and basic sites on metal oxides by a simple IR experiment. (C) 2012 Elsevier B.V. All rights reserved.
• Structural features of isomerizable aspartyl residues in human alpha-crystallins

  Ken-ichi Shimizu, Akiko Kita, Noriko Fujii, Kunio Miki

  MOLECULAR VISION 18 187-90 1823 - 1827 2012年07月 [査読有り][通常論文]
   

  Purpose: The aspartyl (Asp) residues 58 and 151 in alpha A-crystallin, and Asp36 and Asp62 in alpha B-crystallin in human lenses are known to be highly isomerized with aging. We investigate structural environments of these isomerizable aspartyl residues in alpha-crystallins of human lenses. Methods: To perform limited proteolysis experiments of purified human alpha A-and alpha B-crystallins, endoproteinase Asp-N (EC 3.4.24.33), which selectively cleaves the peptide bonds at the amino side of aspartyl and cysteic acid residues, was employed. By proteolysis approach coupled with the time-of-flight mass spectrometry (TOF-MS) method, we determined the cleavage points along protein sequences. Results: Proteolysis by endoproteinase Asp-N occurred preferentially at the site of isomerizable aspartyl residues in alpha A- and alpha B-crystallins. Conclusions: It is found that isomerizable aspartyl residues in alpha-crystallins in human lenses were located not only in the solvent accessible area but also at regions displaying inherent conformational flexibility.
• Unique effect of surface area of support on propene combustion over Pd/ceria

  Atsushi Satsuma, Ryota Sato, Kaoru Osaki, Kenichi Shimizu

  CATALYSIS TODAY 185 1 61 - 65 2012年05月 [査読有り][通常論文]
   

  The effects of calcination temperature and surface area of ceria support on the propene oxidation over Pd/ceria were investigated. Very unique dependence of the oxidation activity of Pd/ceria on surface area was observed, i.e. lower surface area of ceria is more preferable for the higher catalytic activity depending on the pretreatment conditions. The structure of supported Pd species was characterized by Pd K-edge EXAFS. Isolated Pd ions were stable on ceria with high surface area after the propene oxidation, which was caused by the easy oxidation of Pd species and formation of Pd-O-Ce bond. On the other hand, moderately dispersed Pd metal particles were abundant on ceria with low surface area. It was suggested that the weaker interaction with sintered ceria is suggested to be preferable for the formation of active Pd metal particles by the reduction at low temperatures. (C) 2011 Elsevier B.V. All rights reserved.
• Hydration of nitriles to amides in water by SiO2-supported Ag catalysts promoted by adsorbed oxygen atoms

  Ken-ichi Shimizu, Naomichi Imaiida, Kyoichi Sawabe, Atsushi Satsuma

  APPLIED CATALYSIS A-GENERAL 421 114 - 120 2012年04月 [査読有り][通常論文]
   

  A series of silica-supported silver catalysts with similar Ag loading (5 or 7 wt%) but with different preparation methods (calcination in air and reduction by H-2 or NaBH4) were prepared, and their structure was characterized by microscopy (STEM), X-ray absorption fine structure (XAFS). and CO-titration of surface oxygen atom. Ag is present as metal nanoparticle with a size range of 17-30 nm. Their surface was partially covered with oxygen atoms, and the surface coverage of the oxygen depends on the preparation condition. For hydration of 2-cyanopyridine as a test reaction, turnover frequency (TOF) per surface Ag species is estimated. TOF does not show a good correlation with Ag particle size, but it linearly increases with the coverage of the surface oxygen atoms on Ag particles. The Ag/SiO2 catalyst prepared by H-2 reduction at 700 degrees C shows the highest TOF and it acts as effective and recyclable heterogeneous catalyst for selective hydration of various nitriles to the corresponding amides. Kinetic and Raman spectroscopic studies suggest that the surface oxygen atom adjacent to Ag-0 sites plays an important role in the dissociation of H2O. (C) 2012 Elsevier B.V. All rights reserved.
• 金属酸化物修飾Au電極を用いた混成電位式アンモニアセンサ

  菅谷聡, 柿元志郎, 中埜吉博, 小島多喜男, 清水研一, 薩摩篤

  Chem Sens 28 Supplement A 139 - 141 電気化学会化学センサ研究会 2012年03月29日 [査読無し][通常論文]
  
• Kinetic analysis of reduction process of supported Rh/Al2O3 catalysts by time resolved in-situ UV-vis spectroscopy

  Qiang Lin, Ken-ichi Shimizu, Atsushi Satsuma

  APPLIED CATALYSIS A-GENERAL 419 142 - 147 2012年03月 [査読有り][通常論文]
   

  Kinetic analysis of reduction of Rh/Al2O3 with low Rh-loadings (0.01-0.1 wt%) has been carried out by time resolved in-situ UV-vis spectroscopy. Based on XAFS and UV-vis spectra, it was indicated that Rh was present as surface isolated Rh3+ on catalyst calcined at 773 K in air. The rate of reduction of Rh3+ to metallic Rh was determined by in-situ UV-vis measurements under a flow of 1%H-2/He at 523-823 K. The reduction rate increased with Rh-loading but decreased as the calcination temperature elevated. The decrease of metallic Rh-0 formation with the calcination temperature was in harmony with the reaction rate of CO oxidation. The apparent activation energy (E-a) for the reduction of Rh3+ to Rh-0 was found to be constant around 60-62 kJ mol(-1) and independent of the calcination temperature and the Rh-loading, indicating the equivalent intrinsic activity of supported Rh species on Rh/Al2O3 with the low Rh-loadings. (C) 2012 Elsevier B.V. All rights reserved.
• ナノ界面の世界と次世代機能 自動車排ガス浄化用自己再生型Agナノクラスター触媒

  清水研一, 沢邊恭一, 薩摩篤

  化学工業 63 3 213 - 218 化学工業社 2012年03月01日 [査読無し][通常論文]
  
• Surface oxygen-assisted Pd nanoparticle catalysis for selective oxidation of silanes to silanols.

  Ken-ichi Shimizu, Takahiro Kubo, Atsushi Satsuma

  Chemistry (Weinheim an der Bergstrasse, Germany) 18 8 2226 - 9 2012年02月20日 [査読有り][通常論文]
   

  Just add O(2): Based on the fact that an oxygen-adsorbed Pd metal surface shows higher reactivity for water dissociation than a clean Pd surface, carbon-supported Pd nanoparticles (NPs) with surface oxygen atoms were developed as a highly effective and reusable heterogeneous catalyst for selective oxidation of silanes to silanols with water as a green oxidant (see figure).
• Electronic effect of Na promotion for selective mono-N-alkylation of aniline with di-iso-propylamine by Pt/SiO2 catalysts

  Ken-ichi Shimizu, Katsuya Shimura, Kazuo Kato, Naoko Tamagawa, Masazumi Tamura, Atsushi Satsuma

  JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL 353 171 - 177 2012年02月 [査読有り][通常論文]
   

  Sodium promoted 5 wt.% Pt/SiO2 catalysts with similar Pt particle size (2.9-3.5 nm) but with different Na loadings (Na/Pt ratio of 0-10) were prepared by a sequential impregnation method. The catalysts were well characterized by Pt L-3-edge XAFS (X-ray absorption fine structure), X-ray photoelectron spectroscopy (XPS), infrared (IR) study of CO adsorption. Their catalytic activity for mono-N-alkylation of aniline with iPr(2)NH, as a test reaction for cross-coupling reaction of different amines, showed a volcano type dependence on the Na/Pt ratio. The catalyst with Na/Pt ratio of 2 showed the highest intrinsic activity. The Na/Pt ratio also affected the electronic states of the support oxide and Pt: the electron densities of Pt and surface oxygen atoms of support oxides increased with the Na/Pt ratio. From the structure-activity relationship, it is shown that the moderate electron densities of Pt and support oxygen atoms lead to the high catalytic activity. Kinetic studies suggest that the present reaction proceeds through a hydrogen-borrowing mechanism that begins with dehydrogenation of iPr(2)NH as the rate-limiting step. Based on the mechanistic and structural results, origin of the promotional effect of Na on the catalytic activity of Pt/SiO2 is discussed. (C) 2011 Elsevier B.V. All rights reserved.
• Sulfur promoted Pt/SiO2 catalyzed cross-coupling of anilines and amines

  Ken-ichi Shimizu, Katsuya Shimura, Naoko Tamagawa, Masazumi Tamura, Atsushi Satsuma

  APPLIED CATALYSIS A-GENERAL 417 37 - 42 2012年02月 [査読有り][通常論文]
   

  Pt/SiO2 (Pt = 5 wt%) catalysts with average Pt particle size of 3.3 and 6.8 nm and sulfur-loaded Pt/SiO2 (S/Pt ratio = 0.1 and 0.13; Pt size = 5.2 and 5.5 nm), prepared by adding ammonium sulfate on Pt/SiO2 followed by H-2-reduction at 500 degrees C, are tested for mono-N-alkylation of aniline with di-iso-propylamine. The turnover frequency (TOF), defined as the reaction rate per number of surface Pt species, increases with sulfur loading. The catalyst with S/Pt ratio of 0.13 shows more than 5 times higher TOF than unmodified catalysts, and it acts as effective and recyclable catalyst for cross-coupling of various anilines and amines. Combined with kinetic results and characterizations, XAFS (X-ray absorption fine structure), TEM, and CO adsorption IR, a possible reason for the promotion effect of sulfur species (probably sulfidic species) is discussed. (C) 2011 Elsevier B.V. All rights reserved.
• CeO2-catalyzed one-pot selective synthesis of N-alkyl amides from nitriles, amines and water

  Masazumi Tamura, Takuya Tonomura, Ken-ichi Shimizu, Atsushi Satsuma

  APPLIED CATALYSIS A-GENERAL 417 6 - 12 2012年02月 [査読有り][通常論文]
   

  Among 13 kinds of metal oxides, ceria (CeO2) shows the highest catalytic activity for one-pot selective synthesis of the secondary amide from 2-cyanopyridine and n-octylamine as a test reaction. CeO2 acts as a reusable heterogeneous catalyst, and it is effective for the secondary amide formation from various nitriles and amines in high yields (73% to >99%). Pharmacologically important products such as heteroaromatic N-alky amides and morpholine amide are effectively synthesized, indicating that CeO2 can be a practically useful catalyst. A proposed mechanism includes (1) hydration of nitrile to the primary amide and (2) transamidation of the primary amide with amine as the rate-limiting step. This reaction mechanism provides a reason why the present catalytic system gives high selectivity. (C) 2011 Elsevier B.V. All rights reserved.
• Pt/Fe-containing alumina catalysts prepared and treated with water under moderate conditions exhibit low-temperature CO oxidation activity

  Atsuko Tomita, Ken-ichi Shimizu, Kazuo Kato, Yutaka Tai

  CATALYSIS COMMUNICATIONS 17 194 - 199 2012年01月 [査読有り][通常論文]
   

  Pt/Fe-containing alumina catalysts were prepared and treated with water under moderate conditions. From transmission electron microscopy and Pt L-m extended X-ray absorption fine structure measurement, it was concluded that Pt nanoparticles and iron oxides formed efficient contacts in the catalysts probably because of the enhanced mobility of Pt species. Surprisingly, these catalysts could catalyze CO oxidation at low temperatures-even below 0 degrees C with very low apparent activation energy (9.2 kl/mol). The concept of interface fabrication demonstrated in this paper has the potential to be applied widely to various heterogeneous Pt-promoter catalytic systems. (C) 2011 Elsevier B.V. All rights reserved.
• Quantitative determination of average rhodium oxidation state by a simple XANES analysis

  Ken-ichi Shimizu, Tomonori Oda, Yoshinori Sakamoto, Yuichi Kamiya, Hisao Yoshida, Atsushi Satsuma

  APPLIED CATALYSIS B-ENVIRONMENTAL 111 509 - 514 2012年01月 [査読有り][通常論文]
   

  Quantitative determination of average rhodium oxidation state for supported rhodium catalyst was examined by using Rh L-3-edge XANES (X-ray absorption near-edge structure) spectra. A series of Rh-loaded SiO2 catalysts (Rh2Ox/SiO2) containing different amount of Rh metal and Rh2O3 phases were prepared, and the average oxidation number (x) was determined by the amount of CO2 formed during CO reduction treatment as the final step of catalyst preparation. L-3-edge XANES spectra of these samples were recorded, and the white line area intensity of the spectra was evaluated. A good linear relationship was confirmed between the white line area intensity and the average oxidation number (x), indicating that the oxidation state of Rh species in structurally unknown Rh samples could be quantitatively determined by a simple L-3-edge XANES analysis. The effect of the oxidation number (x) on the Rh2O/SiO2-catalysed CO oxidation was discussed, in order to demonstrate a utility of this method in a catalytic study. (C) 2011 Elsevier B.V. All rights reserved.
• The average Pd oxidation state in Pd/SiO2 quantified by L-3-edge XANES analysis and its effects on catalytic activity for CO oxidation

  Ken-ichi Shimizu, Yuichi Kamiya, Kaoru Osaki, Hisao Yoshida, Atsushi Satsuma

  CATALYSIS SCIENCE & TECHNOLOGY 2 4 767 - 772 2012年 [査読有り][通常論文]
   

  The palladium oxidation state of an SiO2-supported palladium catalyst was quantitatively determined by Pd L-3-edge XANES (X-ray absorption near-edge structure) analysis. By changing the time of CO-reduction pre-treatment at 673 K, a series of 5 wt% Pd-loaded SiO2 catalysts (PdOx/2/SiO2) containing different amounts of the Pd metal and PdO phases were prepared, and the average oxidation number (x) was estimated from the number of CO2 molecules formed during the CO-reduction treatment. L-3-edge XANES spectra of these samples and a reference sample (Pd powder) were recorded, and the white line area of the spectra was evaluated. A good linear relationship was confirmed between the white line area intensity and the average oxidation number (x), indicating that the oxidation state of Pd in structurally unknown Pd samples could be quantitatively determined by a simple XANES analysis. To demonstrate the utility of this method in a catalytic study, the effect of the oxidation number (x) on the CO oxidation activity of PdOx/2/SiO2 was also examined, and metallic Pd-0 sites in PdOx/2/SiO2 were shown to be active species.
• 担持Pd触媒上での低温CO酸化反応における活性制御因子

  薩摩 篤, 大崎 薫, 大山 順也, 清水 研一

  石油学会 年会・秋季大会講演要旨集 2012 39 - 39 公益社団法人 石油学会 2012年 

  CeO2, TiO2, Al2O3, ZrO2の担体にPdを担持した触媒を用いてCO酸化反応及びCO-TPRを行い比較検討した。CO酸化反応における着火温度はCeO2, TiO2担体上で100℃以下であったのに対して Al2O3, ZrO2では50℃以上高温で着火した。このような低温での活性の違いは、(1)Pdが反応中に還元しやすいかどうかと、(2)金属表面がCOで被毒された場合でも担体での酸素の活性化の2つの因子で説明できることを、CO-TPR, in-situ FT/IR, 速度論により示す。
• Transamidation of amides with amines under solvent-free conditions using a CeO2 catalyst

  Masazumi Tamura, Takuya Tonomura, Ken-ichi Shimizu, Atsushi Satsuma

  GREEN CHEMISTRY 14 3 717 - 724 2012年 [査読有り][通常論文]
   

  Among various metal oxides, cerium oxide (CeO2) shows the highest catalytic activity for transamidation of picolinamide with n-octylamine. CeO2 acts as a reusable and effective heterogeneous catalyst for transamidation under solvent-free conditions. Transamidation of a variety of amides and amines produced the corresponding N-alkyl amides in high yields. This method provides the first example of a heterogeneous catalyst for transamidation using aliphatic amines as substrates. Characterization of acid base properties and kinetic studies suggest that the cooperation of the weak Lewis acid sites and adjacent strong base sites play important roles in the transamidation reaction.
• Size- and support-dependent selective amine cross-coupling with platinum nanocluster catalysts

  Ken-ichi Shimizu, Keiichiro Ohshima, Yutaka Tai, Masazumi Tamura, Atsushi Satsuma

  CATALYSIS SCIENCE & TECHNOLOGY 2 4 730 - 738 2012年 [査読有り][通常論文]
   

  gamma-Alumina-supported Pt nanoclusters with an average particle size of 0.8 nm, Pt/Al2O3-0.8, act as an effective heterogeneous catalyst for mono-N-alkylation of amines with different amines. To establish a catalyst design concept, systematic studies on the structure-activity relationship are carried out, combined with characterization by Pt L-3-edge XAFS (X-ray absorption fine structure), X-ray photoelectron spectroscopy (XPS), and infrared (IR) study of CO adsorption. By changing the particle size of Pt over the size range of 0.8-24 nm, it is demonstrated that the present reaction is a structure-sensitive reaction, demanding coordinatively unsaturated Pt atoms on metallic nanoclusters. The support also affects the activity and electronic state of Pt. The electron density of Pt increases with basicity of the support oxide, and the support with moderate basicity (Al2O3) gives the highest activity probably due to a moderate electron density of Pt. Kinetic studies suggest that the present reaction proceeds through a "hydrogen-borrowing" mechanism.
• CeO2-catalysed one-pot selective synthesis of esters from nitriles and alcohols

  Masazumi Tamura, Takuya Tonomura, Ken-ichi Shimizu, Atsushi Satsuma

  GREEN CHEMISTRY 14 4 984 - 991 2012年 [査読有り][通常論文]
   

  Thirteen kinds of metal oxides were tested for one-pot selective synthesis of esters from nitriles and alcohols. Ceria (CeO2) showed more than two orders of magnitude higher activity than the other oxides. CeO2 acted as a reusable and effective catalyst for the ester synthesis from various nitriles and alcohols under neutral and solvent-free conditions at 160 degrees C. This method provides a rare example for the synthesis of heteroaromatic esters, which have been difficult to synthesize by conventional catalytic esterification methods. Valuable esters such as picolinic acid alkyl esters and niacin benzyl esters were synthesized, demonstrating a practical aspect of the present method. Kinetic studies suggested the following reaction mechanism: (1) H2O and ROH dissociate on CeO2, (2) nucleophilic attack of hydroxyl species (OH delta-) to the adsorbed nitrile on CeO2, leading to the formation of the primary amide, (3) nucleophilic attack of alkoxide species (OR delta-) to the amide as the rate-limiting step.
• Transfer hydrogenation of ketones by ceria-supported Ni catalysts

  Katsuya Shimura, Ken-ichi Shimizu

  GREEN CHEMISTRY 14 11 2983 - 2985 2012年 [査読有り][通常論文]
   

  Ni-loaded CeO2, prepared by H-2-reduction of NiO-loaded CeO2, was found to be an effective and recyclable catalyst for the transfer hydrogenation of aliphatic and aromatic ketones by 2-propanol to the corresponding alcohols under base free conditions with low catalyst loading (1-3 mol%).
• Direct Synthesis of N-Substituted Anilines from Nitroaromatics and Alcohols under H2 by Alumina-Supported Silver Cluster Catalysts

  Kenichi Shimizu, Katsuya Shimura, Masanari Nishimura, Atsushi Satsuma

  CHEMCATCHEM 3 11 1755 - 1758 2011年11月 [査読有り][通常論文]
  
• Silver Cluster Catalysts for Green Organic Synthesis

  Ken-ichi Shimizu, Atsushi Satsuma

  JOURNAL OF THE JAPAN PETROLEUM INSTITUTE 54 6 347 - 360 2011年11月 [査読有り][招待有り]
   

  Development of platinum-group-metal (PGM)-free catalysts for green chemical synthesis is an important topic in synthetic catalysis, because PGM will soon be in short supply in the near future. Our group has paid attention to the catalytic functions of Ag clusters. Here, we summarize our recent work on size- and support-specific catalysis of Ag clusters for green organic synthesis. Ag clusters supported on Al2O3 act as effective heterogeneous catalysts for (I) oxidant-free dehydrogenation of alcohols to carbonyl compounds, (2) coupling of alcohols with amines to form amides and H-2, (3) N-alkylation of anilines with alcohols, (4) C-C cross-coupling reaction of alcohols, (5) selective hydrogenation of nitroaromatics, and (6) direct synthesis of N-substituted anilines from nitroaromatics and alcohols. To establish a catalyst design concept, effects of Ag particle size and acid-base character of support oxides are investigated. The structure-activity relationships for all reactions show similar tendencies; metallic Ag clusters with smaller size and acid-base bifunctional nature of the support oxide are preferable. We propose that cooperation between coordinatively unsaturated Ag sites of Ag clusters and acid-base pair sites at the metal-support interface is a key concept for the design of Ag cluster catalysts for the above reactions.
• Direct Synthesis of N-Substituted Anilines from Nitroaromatics and Alcohols under H2 by Alumina-Supported Silver Cluster Catalysts

  Kenichi Shimizu, Katsuya Shimura, Masanari Nishimura, Atsushi Satsuma

  CHEMCATCHEM 3 11 1755 - 1758 2011年11月 [査読有り][通常論文]
  
• Sintering-resistant and self-regenerative properties of Ag/SnO2 catalyst for soot oxidation

  Ken-ichi Shimizu, Makoto Katagiri, Shigeo Satokawa, Atsushi Satsuma

  APPLIED CATALYSIS B-ENVIRONMENTAL 108 1-2 39 - 46 2011年10月 [査読有り][通常論文]
   

  Key factors controlling the thermal and redox-cycle stability of Ag/SnO2 catalyst were investigated to establish the design concept of "self-regenerative" soot oxidation catalysts. The effect of thermal aging (in air at 1000 degrees C) on the soot oxidation activity was tested for Ag catalysts supported on SnO2, CeO2, ZrO2, TiO2, and MgO and SnO2-supported Cu, Pd, Rh, Ru, and Pt. Ag/SnO2 is found to be the most effective catalysts in terms of both activity and thermal stability. XRD and EXAFS results showed that particle growth of metal or metal oxide by the thermal aging was the main reason of the decreased soot oxidation activity, and the supported Ag species on Ag/SnO2 showed high sintering-resistance owing to the Ag-O-Sn bonds at metal-support interface. The effect of redox aging at 800 degrees C on the soot oxidation activity and structure of Ag/SnO2 was also studied. H-2-reduction of Ag/SnO2 lead to the formation of the large (20 nm) particles of Ag3Sn, which were then redispersed by the reoxidation treatment to small Ag nanoparticles. This self-regenerative property lead to no catalyst deactivation of Ag/SnO2 after successive redox treatments. It is concluded that the strong chemical interaction between silver and tin species (metallic and oxidic Sn) under both reductive and oxidative environments at high-temperature enables the design of highly sintering resistant Ag-based oxidation catalysts. (C) 2011 Elsevier B.V. All rights reserved.
• Efficient and Substrate-Specific Hydration of Nitriles to Amides in Water by Using a CeO2 Catalyst

  Masazumi Tamura, Hiroko Wakasugi, Ken-ichi Shimizu, Atsushi Satsuma

  CHEMISTRY-A EUROPEAN JOURNAL 17 41 11428 - 11431 2011年10月 [査読有り][通常論文]
  
• Carbon oxidation with Ag/ceria prepared by self-dispersion of Ag powder into nano-particles

  Ken-ichi Shimizu, Hiroshi Kawachi, Shin-ichi Komai, Kaname Yoshida, Yukichi Sasaki, Atsushi Satsuma

  CATALYSIS TODAY 175 1 93 - 99 2011年10月 [査読有り][通常論文]
   

  This study reports a unique and novel method of preparation of Ag/CeO2 catalyst for carbon oxidation. A calcination of physical mixture of Ag metal powder and CeO2 at 500 degrees C results in self-dispersion of Ag into nano-particles on CeO2. From TEM images, the average diameter of Ag particles in Ag power before calcination was around 66 nm, while the particle size of Ag became smaller around 8 nm with very narrow distribution. Oxygen vacancy on CeO2 surface is suggested to play an important role in the self-dispersion of Ag. The obtained catalyst showed high activity for soot oxidation comparable to Ag/CeO2 prepared by impregnation method. The promotion effect of CeO2 was not observed in physical mixtures with Cu, Au and Pt. Mechanical mixtures of Ag and various metal oxide supports were also examined. The addition of Ag to CeO2, SnO2, ZrO2, ZnO, TiO2, and Nb2O5 significantly lowered the temperature of carbon oxidation than those of supports, while that to Co3O4, CaO, La2O3, NiO, SiO2, Al2O3 and MgO did not. (C) 2011 Elsevier B.V. All rights reserved.
• Toward a rational control of solid acid catalysis for green synthesis and biomass conversion

  Ken-ichi Shimizu, Atsushi Satsuma

  ENERGY & ENVIRONMENTAL SCIENCE 4 9 3140 - 3153 2011年09月 [査読有り][招待有り]
   

  Design of solid acid catalysts is one of the key technologies to establish environmental friendly catalytic processes. Featuring cation-exchanged clay and metal salts of heteropolyacids as model solid acid catalysts, a strategy for design of active catalysts for green chemical and biomass conversion processes is discussed. The important role of solid Lewis acids was suggested in acetylation of alcohols with acetic anhydride by cation-exchanged clay, Friedel-Crafts acylation and alkylation of aromatic compounds with metal salts of heteropolyacids, and hydrolysis of cellulose into saccharides. The significant influence of reactor design and reaction conditions on dehydration of saccharides into 5-hydroxymethylfurfural (HMF) is also discussed.
• Self-Regenerative Silver Nanocluster Catalyst for CO Oxidation

  Ken-ichi Shimizu, Kyoichi Sawabe, Atsushi Satsuma

  CHEMCATCHEM 3 8 1290 - 1293 2011年08月 [査読有り][通常論文]
  
• Selective hydrogenation of nitrocyclohexane to cyclohexanone oxime by alumina-supported gold cluster catalysts

  Ken-ichi Shimizu, Takumi Yamamoto, Yutaka Tai, Atsushi Satsuma

  JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL 345 1-2 54 - 59 2011年07月 [査読有り][通常論文]
   

  Metal oxides (Al2O3, SiO2, MgO)-supported Au cluster catalysts prepared by colloid deposition method and well established Au/TiO2 prepared by deposition-precipitation method were tested for the selective reduction of nitrocyclohexane into cyclohexanone oxime. The activity and selectivity depended strongly on the size of Au and support material. Au/Al2O3 with smaller Au particle size (2.5 nm) was the most effective catalyst, exhibiting a high cyclohexanone oxime yield (86%) under mild condition (0.6 MPa H-2, 100 degrees C). To study the origin of support and size effects, in situ FTIR experiments for OH/D-2 exchange reaction and nitrobenzene adsorption combined with poisoning experiments using pyridine and acetic acid were carried out. It is suggested that cooperation of coordinatively unsaturated Au atoms and the acid-base pair site (Al delta+-O delta- site) plays an important role in H-2 dissociation step. Al delta+-O delta- site also acts as the adsorption site of the nitro group. (C) 2011 Elsevier B.V. All rights reserved.
• Addition of olefins to acetylacetone catalyzed by cooperation of Bronsted acid site of zeolite and gold cluster

  Ken-ichi Shimizu, Takumi Yamamoto, Yutaka Tai, Kazu Okumura, Atsushi Satsuma

  APPLIED CATALYSIS A-GENERAL 400 1-2 171 - 175 2011年06月 [査読有り][通常論文]
   

  HY zeolite-supported Au clusters ((AuHY)-H-0) prepared by deposition-precipitation method, well characterized by XANES. EXAFS, and NH3- and acetyl acetone-adsorption IR, were tested for addition of acetyl acetone to alkenes. (AuHY)-H-0 showed higher selectivity to the addition product than HY zeolite-supported Au(OH)(3) and Au clusters supported on NH4+-exchanged Y zeolite, Al2O3, MgO, SiO2, and TiO2. Studies on the effect of Au oxidation state, Au cluster size and Bronsted acidity of zeolite on the catalytic showed that co-presence of metallic Au with smaller cluster size and the acidic OH groups of the zeolite was necessary to the selective formation of the addition product. Cooperation mechanism of the Bronsted acid sites of the zeolite and Au clusters is proposed. (C) 2011 Elsevier B.V. All rights reserved.
• Effect of acidity and pore diameter of zeolites on detection of base molecules by zeolite thick film sensor

  Atsushi Satsuma, Daojin Yang, Ken-ichi Shimizu

  MICROPOROUS AND MESOPOROUS MATERIALS 141 1-3 20 - 25 2011年05月 [査読有り][通常論文]
   

  In order to investigate molecular recognition by zeolite thick film gas sensors, the effect of zeolite acidity and pore diameter of zeolites on the detection of base molecules (water, acetonitrile, ammonia, benzonitrile, pyridine, aniline, and triethylamine) was investigated. The impedance spectra of the thick film sensors of H-type zeolites (MFI, MOR and BEA) showed a semicircle attributable to an RC parallel equivalent circuit from 4 Hz to 1 MHz, and resistance R decreased in the presence of 300 ppm of base molecules at 673 K. For smaller molecules having molecular diameter of less than 0.4 nm (water, acetonitrile, and ammonia), a good correlation was observed between the response magnitude of R and the proton affinity of base molecules. It was indicated that acid-base interaction is the major factor when molecular diameter is smaller enough than zeolite pore diameter. As for larger molecules (benzonitrile, pyridine, aniline, and triethylamine) of which the molecular diameter is nearly the pore diameter of zeolites, the response magnitudes were lower than those of smaller molecules. Quantification of adsorbed species by in situ FT/IR revealed that the response magnitude for larger molecules significantly depends on the mobility of migrating species controlled by relative size of molecules to zeolite pore diameter. (C) 2009 Elsevier Inc. All rights reserved.
• Effects of Calcination Temperature and Acid-Base Properties on Mixed Potential Ammonia Sensors Modified by Metal Oxides

  Atsushi Satsuma, Makoto Katagiri, Shiro Kakimoto, Satoshi Sugaya, Kenichi Shimizu

  SENSORS 11 2 2155 - 2165 2011年02月 [査読有り][通常論文]
   

  Mixed potential sensors were fabriated using yttria-stabilized zirconia (YSZ) as a solid electrolyte and a mixture of Au and various metal oxides as a sensing electrode. The effects of calcination temperature ranging from 600 to 1,000 degrees C and acid-base properties of the metal oxides on the sensing properties were examined. The selective sensing of ammonia was achieved by modification of the sensing electrode using MoO3, Bi2O3 and V2O5, while the use of WO3, Nb2O5 and MgO was not effective. The melting points of the former group were below 820 degrees C, while those of the latter group were higher than 1,000 degrees C. Among the former group, the selective sensing of ammonia was strongly dependent on the calcination temperature, which was optimum around melting point of the corresponding metal oxides. The good spreading of the metal oxides on the electrode is suggested to be one of the important factors. In the former group, the relative response of ammonia to propene was in the order of MoO3 > Bi2O3 > V2O5, which agreed well with the acidity of the metal oxides. The importance of the acidic properties of metal oxides for ammonia sensing was clarified.
• Effects of Calcination Temperature and Acid-Base Properties on Mixed Potential Ammonia Sensors Modified by Metal Oxides

  Atsushi Satsuma, Makoto Katagiri, Shiro Kakimoto, Satoshi Sugaya, Kenichi Shimizu

  SENSORS 11 2 2155 - 2165 2011年02月 [査読有り][通常論文]
   

  Mixed potential sensors were fabriated using yttria-stabilized zirconia (YSZ) as a solid electrolyte and a mixture of Au and various metal oxides as a sensing electrode. The effects of calcination temperature ranging from 600 to 1,000 degrees C and acid-base properties of the metal oxides on the sensing properties were examined. The selective sensing of ammonia was achieved by modification of the sensing electrode using MoO3, Bi2O3 and V2O5, while the use of WO3, Nb2O5 and MgO was not effective. The melting points of the former group were below 820 degrees C, while those of the latter group were higher than 1,000 degrees C. Among the former group, the selective sensing of ammonia was strongly dependent on the calcination temperature, which was optimum around melting point of the corresponding metal oxides. The good spreading of the metal oxides on the electrode is suggested to be one of the important factors. In the former group, the relative response of ammonia to propene was in the order of MoO3 > Bi2O3 > V2O5, which agreed well with the acidity of the metal oxides. The importance of the acidic properties of metal oxides for ammonia sensing was clarified.
• Redox tunable reversible molecular sieves: orthorhombic molybdenum vanadium oxide

  Masahiro Sadakane, Shunpei Ohmura, Katsunori Kodato, Takumi Fujisawa, Kazuo Kato, Ken-ichi Shimidzu, Toru Murayama, Wataru Ueda

  CHEMICAL COMMUNICATIONS 47 38 10812 - 10814 2011年 [査読有り][通常論文]
   

  We demonstrated that the sorption behavior of orthorhombic Mo-V oxide (Mo(29)V(11)O(112-x)) is continually and reversibly tunable by redox treatment.
• Silver cluster-promoted heterogeneous copper catalyst for N-alkylation of amines with alcohols

  Ken-ichi Shimizu, Katsuya Shimura, Masanari Nishimura, Atsushi Satsuma

  RSC ADVANCES 1 7 1310 - 1317 2011年 [査読有り][通常論文]
   

  A series of metal(M)-loaded Al2O3 catalysts (M/Al2O3) and bimetallic catalysts, CuxAg1-x/Al2O3 with different compositions, Cu0.95Ag0.05/MOx with different supports (MOx), and Cu0.95M'(0.05)/Al2O3 with different promoter (M'), were prepared by an impregnation method, followed by H-2-reduction at 600 degrees C. For the N-alkylation of amines with alcohols, Al2O3-supported copper-silver bimetallic catalysts with a Cu/Ag molar ratio of 95/5 (Cu0.95Ag0.05/Al2O3) was found to be the most effective heterogeneous catalyst. The alkylation of anilines and aliphatic amines with various alcohols (benzyl and aliphatic alcohols) was achieved with a small amount of the catalyst (1 mol%). Mechanistic studies show that the reaction proceeds through a hydrogen-borrowing mechanism initiated by alcohol dehydrogenation as the rate-limiting step. Structural studies indicate that small Ag nanoclusters are supported on Cu nanoparticles possibly through Ag-O-Cu bonds at the silver-copper boundary. This bimetallic structure can be crucial to an effective promotion of the alcohol dehydrogenation and hydride transfer to the imines.
• Unique catalytic features of Ag nanoclusters for selective NOx reduction and green chemical reactions

  Kenichi Shimizu, Kyoichi Sawabe, Atsushi Satsuma

  CATALYSIS SCIENCE & TECHNOLOGY 1 3 331 - 341 2011年 [査読有り][通常論文]
   

  The size control of Ag into nanoclusters generates unique catalytic features of Ag on automotive emission control and environmentally friendly organic reactions. Hydrogen-assisted selective catalytic reduction of NO by hydrocarbons (H-2-HC-SCR), which is one of the promising technologies for removal of NO in the diesel engine exhausts, results in the formation of Ag clusters on alumina or zeolites and enhancement of the conversion of NO into N-2. A mechanistic study using in situ UV-Vis, EXAFS, and FT/IR revealed that the promotion of partial oxidation of hydrocarbons by active oxygen species is the essential role of Ag clusters. Hydrogen is suggested to be indispensable for the formation of the Ag cluster and the active oxygen. The important role of hydride on the formation of H2O2-like active chemical species on Ag clusters was confirmed by density functional theory (DFT) calculation. Knowing the high activity of Ag nanoclusters for the formation of Ag-hydride, supported Ag clusters were applied for various organic reactions. Supported Ag clusters on appropriate metal oxide, especially Al2O3, are recyclable and show very high activity and selectivity for atom-economic reactions, i.e., alcohol dehydrogenation, C-C coupling reaction of alcohols, direct amide synthesis from alcohols and amines, N-benzylation of anilines with alcohols, and selective hydrogenation of nitroaromatics.
• Selective cross-coupling of amines by alumina-supported palladium nanocluster catalysts

  Ken-ichi Shimizu, Katsuya Shimura, Keiichiro Ohshima, Masazumi Tamura, Atsushi Satsuma

  GREEN CHEMISTRY 13 11 3096 - 3100 2011年 [査読有り][通常論文]
   

  Al2O3-supported Pd nanoclusters with an average particle size of 1.8 nm act as a reusable catalyst for the selective cross-coupling of amines. The reaction is a structure-sensitive reaction, demanding coordinatively unsaturated Pd atoms on a metallic nanocluster. The support also affects the activity, an amphoteric oxide (Al2O3) is most effective.
• Hydrogenation of pyrene using Pd catalysts supported on tungstated metal oxides

  Qiang Lin, Ken-ichi Shimizu, Atsushi Satsuma

  APPLIED CATALYSIS A-GENERAL 387 1-2 166 - 172 2010年10月 [査読有り][通常論文]
   

  A series of Pd catalyst supported on tungstated metal oxides (Pd/W-MOx) were prepared and applied for pyrene hydrogenation, and the role of acid sites of supports was investigated. Among Pd/W-MOx catalysts, Pd/W-TiO2 showed the highest activity which was comparable to those of Pd/BEA. Pd/Y and Pd/SiO2-Al2O3. As for the Pd catalysts supported on metal oxides without tungstate (Pd/MOx), the hydrogenation activity became higher with the increase in the acid amount of supports measured by calorimetric measurement of ammonia adsorption. The important role of acid sites on hydrogenation activity was demonstrated. On the other hand, the hydrogenation activity of Pd/W-MOx catalysts was not correlated to the acid amount of supports measured by ammonia adsorption. On-site generation of protonic acid on tungstated metal oxide supports was estimated from kinetic analysis of reduced W species in the presence of hydrogen by in situ UV-visible measurement. From a good correlation between the kinetic parameters of on-site protonic acid formation and the hydrogenation activity, the important role of protonic acid formation on tungstated metal oxide supports was clarified. (C) 2010 Elsevier B.V. All rights reserved.
• 銀クラスター触媒による脱硝および環境調和型有機合成に関する研究

  清水研一

  触媒 52 6 379 - 380 2010年09月04日 [査読無し][通常論文]
  
• The scope and limitation of the regio- and enantioselective hydrolysis of aliphatic epoxides using Bacillus subtilis epoxide hydrolase, and exploration toward chirally differentiated tris(hydroxymethyl)methanol

  Ken-ichi Shimizu, Maki Sakamoto, Manabu Hamada, Toshinori Higashi, Takeshi Sugai, Mitsuru Shoji

  TETRAHEDRON-ASYMMETRY 21 16 2043 - 2049 2010年08月 [査読有り][通常論文]
   

  The substrate specificity of an engineered Bacillus subtilis epoxide hydrolase, which so far had shown high activity and enantioselectivity with 1-benzyloxymethyl-1 -methyloxirane, has been studied by altering the methyl substituent into hydrogen, oxygen-containing functionalities, and unsaturated homologs. High enantioselectivity (E = 44) was observed with 1-benzyloxymethyl-1-vinyloxirane with a proper catalytic activity. The elaboration of the reaction conditions and work-up procedures enabled a preparative-scale kinetic resolution, to give (R)-2-benzyloxymethyl-3-butene-1,2-diol and its antipodal (R)-epoxide in high ees. (C) 2010 Elsevier Ltd. All rights reserved.
• Density functional theory calculation on the promotion effect of H-2 in the selective catalytic reduction of NOx over Ag-MFI zeolite

  Kyoichi Sawabe, Taisuke Hiro, Ken-ichi Shimizu, Atsushi Satsuma

  CATALYSIS TODAY 153 3-4 90 - 94 2010年08月 [査読有り][通常論文]
   

  Density functional theory (DFT) calculation was used to study the hydrogen promotion effect for the selective catalytic reduction (HC-SCR) of NO over Ag-MFI zeolite The nature of the bond between an Ag atom and MFI is ionic One of the roles of hydrogen addition is to neutralize the cationic Ag atom by forming an AgH molecule We propose that the formation of a Ag-4 cluster is achieved by the AgH diffusion as follows 2AgH+Ag-Z-Ag -> HAg4H-Z -> Ag-4-Z+H-2 With the presence of oxygen, the HAg4H cluster prefers the formation of HOO- adsorbate to the desorption of H-2 O-2 is physisorbed on the Ag-4 cluster. Thus, the HAg4H cluster is important for the activation of oxygen Another role of hydrogen addition is to reproduce the HAg4H cluster from the Ag4 cluster which is generated by the SCR reaction from HOOAg4H species Since time dependent DFT (TD-DFT) calculation shows that the UV absorption bands of the HAg4H cluster are weak, UV-vis measurements are not adequate for the study of the reaction mechanisms of HC-SCR (C) 2010 Elsevier B V All rights reserved
• Effect of Pt and Ba content on NO (x) Storage and Reduction Over Pt/Ba/Al2O3

  Yoshinori Saito, Kenichi Shimizu, Takeshi Nobukawa, Atsuhshi Satsuma

  TOPICS IN CATALYSIS 53 7-10 584 - 590 2010年06月 [査読有り][通常論文]
   

  Effects of Pt and Ba content of Pt/Ba/Al2O3 on NO (x) storage reduction (NSR) catalyst were investigated by means of kinetic analysis of surface nitrates using in situ FT/IR. Turnover frequencies of both storage and reduction of nitrate were significantly enhanced at higher Ba content, while those were higher at lower Pt content below 0.2 wt%.
• Design of active centers for bisphenol-A synthesis by organic-inorganic dual modification of heteropolyacid

  Kenichi Shimizu, Soichiro Kontani, Soichiro Yamada, Go Takahashi, Takahito Nishiyama, Atsushi Satsuma

  APPLIED CATALYSIS A-GENERAL 380 1-2 33 - 39 2010年05月 [査読有り][通常論文]
   

  An effective design of solid acid catalysts for synthesis of bisphenol-A was investigated using organic-inorganic dual modification of heteropolyacids. Among various solid acids, partially Cs-ion exchanged tungstophosphate (Cs2.5H0.5PW12O40) showed the highest turnover frequency, i.e., the initial reaction rate per acid site. The acid strengths estimated by differential heat of ammonia adsorption showed that relatively moderate acid strength is optimum for the intrinsic activity of acid sites. Cs2.5H0.5PW12O40 was further modified by immobilization of mercapto compounds. The addition of 2-diethylamino-ethanethiol (DEAT) to Cs2.5H0.5PW12O40 significantly enhanced both activity and selectivity. When the ratio of DEAT and protonic acid site was unity, the designed catalyst showed comparable bisphenol-A yield and higher turnover number and frequency than those of a conventional ion-exchange resin. The high catalytic activity of the dual modified heteropolyacid is attributed to the microscopically designed active center composed of inorganic protonic acid coupled with immobilized organic thiol group. (C) 2010 Elsevier B.V. All rights reserved.
• Study of active sites and mechanism for soot oxidation by silver-loaded ceria catalyst

  Ken-ichi Shimizu, Hiroshi Kawachi, Atsushi Satsuma

  APPLIED CATALYSIS B-ENVIRONMENTAL 96 1-2 169 - 175 2010年04月 [査読有り][通常論文]
   

  The catalytic behaviors of metal oxides and Ag-loaded CeO2 have been studied for soot oxidation by O-2 in tight contact condition. Ag2O, as the most active oxide among 30 kinds of metal oxides tested, showed high activity even under inert atmosphere. However, Ag2O completely deactivated after the first catalytic run because of its conversion to Ag metal particle, indicating that Ag2O does not act as a catalyst but as a strong oxidant for soot combustion. Ag(20 wt%)-loaded CeO2 (Ag20Ce). consisted of silver metal nanoparticles on CeO2, showed higher activity than CeO2, and the catalyst showed high durability. Kinetic studies for soot oxidation under O-2 and He showed that the activation energy changed in the order CeO2 >Ag2O approximate to Ag20Ce, and activation energy under O-2 was close to those under He, indicating that surface oxygen plays an important role in catalytic soot oxidation in the presence of O-2 and active oxygen species of Ag20Ce and Ag2O have similar nature. Time-resolved UV-vis analysis of Ce4+/Ce3+ redox kinetics under reducing (H-2) and oxidizing (O-2) atmosphere showed that the presence of Ag on CeO2 enhanced the reduction of Ce4+ to Ce3+ but did not enhance the re-oxidation of Ce3+. It is concluded that a strong interaction between supported silver nanoparticle and CeO2 surface results in the formation of highly reducible surface oxygen at silver-ceria interface, whose reactivity for soot oxidation is similar to the surface oxygen of Ag2O. (c) 2010 Elsevier B.V. All rights reserved.
• Depletion of CO oxidation activity of supported Au catalysts prepared from thiol-capped Au nanoparticles by sulfates formed at Au-titania boundaries: Effects of heat treatment conditions on catalytic activity

  Yutaka Tai, Wataru Yamaguchi, Masahisa Okada, Fumihiko Ohashi, Ken-ichi Shimizu, Atsushi Satsuma, Koji Tajiri, Hiroyuki Kageyama

  JOURNAL OF CATALYSIS 270 2 234 - 241 2010年04月 [査読有り][通常論文]
   

  We have investigated the effects of heat treatment in air and H-2/Ar on Au/titania-coated silica aerogel catalysts prepared through adsorption of thiol-capped Au nanoparticles (AuNPs). Sulfur atoms remained on the support surfaces in the form of sulfates upon calcination at temperatures below 773 K. X-ray absorption fine structure and in situ infrared absorption measurements of the catalysts suggested that some of the sulfates affected the catalytic properties of the AuNPs through the interactions between AuNPs and sulfates. The turnover frequency for CO oxidation reaction of the catalysts was enhanced by a factor of 3-5 upon the removal of the sulfates through calcination at 873 K or H-2/Ar treatment at 673 K after calcination at 673 K. These results reveal the importance of the contribution of Au-support interfaces to the CO oxidation efficiency on Au/TiO2 catalyst systems. (C) 2009 Elsevier Inc. All rights reserved.
• Size- and support-dependent silver cluster catalysis for chemoselective hydrogenation of nitroaromatics

  Ken-ichi Shimizu, Yuji Miyamoto, Atsushi Satsuma

  JOURNAL OF CATALYSIS 270 1 86 - 94 2010年03月 [査読有り][通常論文]
   

  Silver clusters on theta-Al2O3 support catalyze highly chemoselective reduction of a nitro group for the reduction of substituted nitroaromatics such as nitrostyrene. These catalysts show higher selectivity than conventional platinum-group metal-based heterogeneous catalysts. Systematic studies on the influence of the metal particle size and support oxides show that the intrinsic activity increases with decrease in the silver particle size, and acid-base bifunctional supports such as Al2O3 give higher activity than acidic or basic supports. Kinetic and in situ infrared studies provide a reaction mechanism which explains fundamental reasons of these tendencies. Cooperation of the acid-base pair site on Al2O3 and the coordinatively unsaturated Ag sites on the silver cluster is responsible for the rate-limiting H-2 dissociation to yield a H+/H- pair at metal/support interface, while the basic site on oxides acts as an adsorption site of nitroaromatics. High chemoselectivity could be attributed to a preferential transfer of the H+/H- pair to the polar bonds in the nitro group. (C) 2009 Elsevier Inc. All rights reserved.
• その場観察(第12回)UV‐vis

  清水研一

  ペトロテック 33 3 219 - 222 石油学会 2010年03月01日 [査読無し][通常論文]
  
• Suitable operational strategy for power interchange operation using multiple residential SOFC (solid oxide fuel cell) cogeneration systems

  Tetsuya Wakui, Ryohei Yokoyama, Ken-ichi Shimizu

  ENERGY 35 2 740 - 750 2010年02月 [査読有り][通常論文]
   

  A suitable operational strategy for a power interchange operation using multiple residential solid oxide fuel cell (SOFC) cogeneration systems for saving energy is investigated by an optimization approach based on mixed-integer linear programming. In this power interchange operation, electricity generated by residential SOFC cogeneration systems is shared among households in a housing complex without allowing a reverse power flow to a commercial electric power system in order to increase electric load factors of the system. For an SOFC cogeneration system operated continuously with the minimum output, two types of operational strategies for the power interchange operation are adopted: an operation to meet the total demand for electricity in intended households by the electricity output of SOFC cogeneration systems and an operation to meet the demand for hot water in each household by the hot water output of the SCFC cogeneration system. To clarify a theoretical limit of the energy-saving effects of the two strategies, this study numerically analyzes optimal operation patterns for 20 households on three representative days. The results show that the former operational strategy, which takes advantage of the high electricity generating efficiency of the SOFC, is more suitable for saving energy as compared to the latter strategy. (C) 2009 Elsevier Ltd. All rights reserved.
• Silica-Supported Silver Nanoparticles with Surface Oxygen Species as a Reusable Catalyst for Alkylation of Arenes

  Ken-ichi Shimizu, Yuji Miyamoto, Atsushi Satsuma

  CHEMCATCHEM 2 1 84 - 91 2010年01月 [査読有り][通常論文]
   

  A series of silica-supported silver catalysts with various Ag loading (3-30wt%) and different treatment (oxidation and subsequent reduction by H-2) were prepared, and their local structures were characterized by extended X-ray absorption fine structure (EXAFS) analysis. In oxidized catalysts, silver were mainly present as small nanoparticles with surface oxygen atoms, and the number of surface oxygen atoms decreased with increased silver loading. The H, reduction of these samples resulted in a removal of the surface oxygen atoms. The structure-activity relationship was studied for the alkyla-tion of anisole with benzyl alcohol and styrene. Ag-I oxide, Ag-I ion, bulk silver metal, and silica-supported silver nanoparticles were non-active species. In contrast, silica-supported silver nanoparticles with the surface oxygen atoms acted as an effective heterogeneous catalyst for the alkylation of arenes with alcohols and styrenes. Kinetic studies in alkylation of anisole with alcohols showed that the cleavage of the alpha-C-H bond of alcohol was the rate-limiting step. It is proposed that the surface oxygen adjacent to the silver surface atoms plays 1 an important role in the dissociation of the alpha-C-H. bond.
• セリア触媒を用いたニトリル化合物のアルキルアミド化

  殿村 拓也, 田村 正純, 清水 研一, 薩摩 篤

  石油学会 年会・秋季大会講演要旨集 2010 11 - 11 公益社団法人 石油学会 2010年 

  当研究室では酸化セリウム触媒(CeO2 )を用いることにより、水溶媒中でのニトリルの水和によるアミド合成反応が効率的に進行することを見出ている。そこで今回、CeO2触媒を用い、ニトリルにアミンと水を反応させることでone-potでのアルキルアミド化反応を試みた。その結果、CeO2 触媒での高活性かつ高選択的なニトリルのアルキルアミド化に世界で初めて成功した。
• アルミナ担持金触媒を用いたニトロスチレンの選択的水素化

  清水 研一, 宮本 裕士, 薩摩 篤, 多井 豊

  石油学会 年会・秋季大会講演要旨集 2010 26 - 26 公益社団法人 石油学会 2010年 

  基礎化学品、ファインケミカルズの製造過程において芳香族ニトロ化合物の選択的水素化反応は重要である。C=C結合を含む官能基が存在する場合、白金族系触媒による接触水素化ではニトロ基の選択的水素化は困難であり、本系に有効な触媒の報告例は極めて少ない。本研究では、アルミナ担持金触媒が表題反応に高い活性、選択性を示すことを見出した。
• 触媒燃焼用Rh/セリアにおける高温エージングの効果

  小田 智徳, 清水 研一, 薩摩 篤

  石油学会 年会・秋季大会講演要旨集 2010 52 - 52 公益社団法人 石油学会 2010年 

  各種金属担持CeO2触媒を用いたCOおよびHCの燃焼反応においてRh/CeO2が特異的挙動を示した。CeO2担体にRhを0.1 wt%担持した触媒は1000℃の高温エージングでも低温(500℃)焼成と同程度の高い燃焼活性を示した。高温エージング後のRh/CeO2の活性は、燃焼触媒として代表的なPt/Al2O3より遙かに高かった。EXAFS測定から、触媒上のRhはイオンとして分散し本系における活性種はRh-O-Ceであると示唆された。
• 担持Pdクラスター触媒を用いたアミンの選択的クロスカップリング反応

  大島 啓一郎, 清水 研一, 薩摩 篤

  石油学会 年会・秋季大会講演要旨集 2010 4 - 4 公益社団法人 石油学会 2010年 

  アルミナ上にPdクラスターを担持したPd/アルミナ触媒が、アミンの選択的クロスカップリング反応に高い触媒活性を示すことを見出した。本系は固体触媒を用いて反応が効率的に進行する初めての報告例である。Pdの粒子径、酸化状態、担体が反応の活性・選択性に与える影響に関しても報告する。
• Cu-Ag合金ナノ粒子を用いた水素添加反応における組成比の影響

  西村 雅翔, 清水 研一, 薩摩 篤

  石油学会 年会・秋季大会講演要旨集 2010 39 - 39 公益社団法人 石油学会 2010年 

  液相還元法により調製したCu‐Ag合金ナノ粒子を用いることで、水素添加反応がCuやAgのみの単一金属触媒と比べ高収率、高選択的に進行することを見出した。また、本反応は担体、粒子径に依存するとともに組成比にも大きく依存し、合金の組成比が反応の選択性を大きく支配していることを明らかにした。
• 酸化セリウムを触媒としたニトリル化合物からのエステルone-pot合成

  田村 正純, 殿村 拓也, 清水 研一, 薩摩 篤

  石油学会 年会・秋季大会講演要旨集 2010 12 - 12 公益社団法人 石油学会 2010年 

  当研究室では、酸化セリウムがニトリルの水和反応を促進すること及び、その触媒活性が酸化セリウムの酸素空孔量に依存していることを見出している。そこで本研究では、酸化セリウムの酸素空孔に吸着することが知られているアルコールを用いたアルコリシス反応及びone-potエステル化反応について検討を行った。その結果、高活性かつ高収率でのone-potエステル化反応に成功した。
• Silica-Supported Silver Nanoparticles with Surface Oxygen Species as a Reusable Catalyst for Alkylation of Arenes

  Ken-ichi Shimizu, Yuji Miyamoto, Atsushi Satsuma

  CHEMCATCHEM 2 1 84 - 91 2010年01月 [査読有り][通常論文]
   

  A series of silica-supported silver catalysts with various Ag loading (3-30wt%) and different treatment (oxidation and subsequent reduction by H-2) were prepared, and their local structures were characterized by extended X-ray absorption fine structure (EXAFS) analysis. In oxidized catalysts, silver were mainly present as small nanoparticles with surface oxygen atoms, and the number of surface oxygen atoms decreased with increased silver loading. The H, reduction of these samples resulted in a removal of the surface oxygen atoms. The structure-activity relationship was studied for the alkyla-tion of anisole with benzyl alcohol and styrene. Ag-I oxide, Ag-I ion, bulk silver metal, and silica-supported silver nanoparticles were non-active species. In contrast, silica-supported silver nanoparticles with the surface oxygen atoms acted as an effective heterogeneous catalyst for the alkylation of arenes with alcohols and styrenes. Kinetic studies in alkylation of anisole with alcohols showed that the cleavage of the alpha-C-H bond of alcohol was the rate-limiting step. It is proposed that the surface oxygen adjacent to the silver surface atoms plays 1 an important role in the dissociation of the alpha-C-H. bond.
• gamma-Alumina-Supported Silver Cluster for N-Benzylation of Anilines with Alcohols

  Kenichi Shimizu, Masanari Nishimura, Atsushi Satsuma

  CHEMCATCHEM 1 4 497 - 503 2009年12月 [査読有り][通常論文]
   

  An alumina-supported silver cluster with a Lewis acidic cocatalyst (polyvalent metal salts, such as FeCl3 center dot 6H(2)O) acts as a heterogeneouos and recyclable catalyst for the direct N-alkylation of anilines with benzyl alcohols, which is driven by the borrowing hydrogen mechanism. Systematic studies on the effects of metal (Pt, Pd, Au, and Ag), silver particle size/support oxides (CeO2, ZrO2, Al2O3, SiO2), and Lewis acidic additives show four important factors required to achieve selective N-alkylation of anilines: 1) metal with a weak metal-hydrogen bond energy (ie., Ag), 2) smaller size of the silver cluster, 3) the support having both acidic and basic sites (ie., Al2O3), and 4) additives with high Lewis acidity (ie., Fe salt). Fundamental information will be useful for the rational design of platinum-group metal-free heterogeneous catalyts for environmentally benign C-N bond forming reactions.
• Dynamic Behavior of Active Ag Species in NOx Reduction on Ag/Al2O3

  Atsushi Satsuma, Ken-Ichi Shimizu

  Molecular Nano Dynamics: Vol. I: Spectroscopic Methods and Nanostructures / Vol. II: Active Surfaces, Single Crystals and Single Biocells 2 401 - 425 2009年11月27日 [査読有り][通常論文]
  
• Chemoselective Hydrogenation of Nitroaromatics by Supported Gold Catalysts: Mechanistic Reasons of Size- and Support-Dependent Activity and Selectivity

  Shimizu, Ken-ichi, Miyamoto, Yuji, Kawasaki, Tadahiro, Tanji, Takayoshi, Tai, Yutaka, Satsuma, Atsushi

  Journal of Physical Chemistry C 113 41 17803 - 17810 2009年10月15日
• Direct Dehydrogenative Amide Synthesis from Alcohols and Amines Catalyzed by γ-Alumina Supported Silver Cluster

  Ken-ichi Shimizu, Keiichiro Ohshima, Atsushi Satsuma

  Chem. Eur. J. 15 39 9977 - 9980 2009年 [査読有り][通常論文]
  
• Redox property of tungstated-zirconia analyzed by time resolved in situ UV-vis spectroscopy

  Lin, Qiang, Shimizu, Ken-ichi, Satsuma, Atsushi

  Applied Catalysis a-General 365 1 2009年
• Oxidant-Free Dehydrogenation of Alcohols Heterogeneously Catalyzed by Cooperation of Silver Clusters and Acid-Base Sites on Alumina

  Shimizu, Ken-ichi, Sugino, Kenji, Sawabe, Kyoichi, Satsuma, Atsushi

  Chemistry-a European Journal 15 10 2009年
• Enhanced production of hydroxymethylfurfural from fructose with solid acid catalysts by simple water removal methods

  Shimizu, Ken-ichi, Uozumi, Rie, Satsuma, Atsushi

  Catalysis Communications 10 14 2009年
• Doped-vanadium oxides as sensing materials for high temperature operative selective ammonia gas sensors

  Shimizu, Ken-ichi, Chinzei, Isao, Nishiyama, Hiroyuki, Kakimoto, Shiro, Sugaya, Satoshi, Matsutani, Wataru, Satsuma, Atsushi

  Sensors and Actuators B-Chemical 141 2 2009年
• Direct C-C Cross-Coupling of Secondary and Primary Alcohols Catalyzed by a gamma-Alumina-Supported Silver Subnanocluster

  Shimizu, Ken-ichi, Sato, Ryosuke, Satsuma, Atsushi

  Angewandte Chemie-International Edition 48 22 2009年
• Characterization of sulfated zirconia prepared using reference catalysts and application to several model reactions

  Matsuhashi, Hiromi, Nakamura, Hideo, Ishihara, Tatsumi, Iwamoto, Shinji, Kamiya, Yuichi, Kobayashi, Junya, Kubota, Yoshihiro, Yamada, Takashi, Matsuda, Takeshi, Matsushita, Koichi, Nakai, Kazuyuki, Nishiguchi, Hiroyasu, Ogura, Masaru, Okazaki, Noriyasu, Sato, Satoshi, Shimizu, Ken-ichi, Shishido, Tetsuya, Yamazoe, Seiji, Takeguchi, Tatsuya, Tomishige, Keiichi, Yamashita, Hiromi, Niwa, Miki, Katada, Naonobu

  Applied Catalysis a-General 360 1 2009年
• Pd担持タングステン酸触媒上での多環芳香族水素化反応における担体効果

  林 強, 清水 研一, 薩摩 篤

  石油学会 年会・秋季大会講演要旨集 2009 93 - 93 公益社団法人 石油学会 2009年 

  担持Pd触媒を用いて、加熱加圧条件で代表的な多環芳香族であるピレンの水素化反応を行った。Pd/WO3/TiO2は既報の高活性触媒に匹敵する活性を示す。担体酸量当たりの活性であるTON(Turnover Number)を比較した。酸量の増加によりTONが増える傾向が見られ、この反応に対する固体酸の関与を示している。発表では、ゼオライト担体のミクロ細孔による拡散阻害、Pd担持タングステン酸触媒の担体効果、また反応活性への制御因子を議論したい。
• 金クラスターと固体酸塩基の協奏的触媒作用によるオキシムの選択合成

  山本 拓実, 清水 研一, 薩摩 篤

  石油学会 年会・秋季大会講演要旨集 2009 133 - 133 公益社団法人 石油学会 2009年 

  金はナノレベルに微小化すると高い触媒活性を発現する事が発見され大きな注目を受けている。さらに最近塩基を助触媒として用いる事で新たな触媒能を発現する事が報告された。本研究では新たな触媒能を開発するために金クラスターと固体酸の協奏効果を利用した不均一系触媒の開発を目的とする。研究の結果、金クラスターを固体酸塩基性が有るアルミナに担持させた触媒でα、β―不飽和ニトロ化合物を選択的に還元しオキシムを合成する事に成功した。
• へテロポリ酸系触媒を用いたセルロース/セロビオースの加水分解－Lewis酸と共役塩基の効果－

  古川 容竹, 清水 研一, 薩摩 篤

  石油学会 年会・秋季大会講演要旨集 2009 149 - 149 公益社団法人 石油学会 2009年 

  バイオマス利用ためのセルロース分解方法として、硫酸を触媒として用いた酸加水分解による方法が代表的であるが、反応容器の腐食、廃触媒処理など問題も多く、新規触媒系の開発が望まれている。本研究ではセルロース分解反応のための触媒設計における基礎的知見を得るため、ヘテロポリ酸を中心としたセルロースおよび二糖であるセロビオース加水分解における構造活性相関を調べた。ヘテロポリ酸触媒はTurnover numberで硫酸を上回り、金属イオン交換により、活性がさらに向上した。金属カチオンのLewis酸としての役割が示唆された。また、種々の均一酸における活性は脱プロトン化エンタルピーと相関が見られ、共役塩基の役割が示唆された。
• Effects of Bronsted and Lewis acidities on activity and selectivity of heteropolyacid-based catalysts for hydrolysis of cellobiose and cellulose

  Ken-ichi Shimizu, Hirotake Furukawa, Nobusuke Kobayashi, Yoshinori Itaya, Atsushi Satsuma

  GREEN CHEMISTRY 11 10 1627 - 1632 2009年 [査読有り][通常論文]
   

  Heteropolyacids (H3PW12O40, H4SiW12O40) and salts of metal cations (Mn+) and PW12O403-M3/nPW12O40) act as effective homogeneous catalysts for selective hydrolysis of cellobiose and cellulose to glucose and total reducing sugars (TRS), respectively, in an aqueous phase. For Bronsted acid catalysts, including mineral acid and heteropolyacids, the activity for both reactions increases with a decrease in the deprotonation enthalpies (DPE), indicating that stronger Bronsted acidity is more favorable. For M3/nPW12O40 of 11 kinds of metal ions (Ag+, Ca2+, Co2+, Y3+, Sn4+, Sc3+, Ru3+, Fe3+, Hf4+, Ga3+ and Al3+), the rate of cellulose hydrolysis increases with Lewis acidity of the cation, while the TRS selectivity was highest for cations with moderate Lewis acidity, such as Sn4+ and Ru3+. For the hydrolysis of cellobiose, cellulose and lignocellulose, H3PW12O40 and Sn0.75PW12O40 showed higher TRS yield than H2SO4.
• Electrical and optical properties of copper-based chalcogenide thin films deposited by pulsed laser deposition at room temperature: Toward p-channel thin film transistor fabricable at room temperature

  Hidenori Hiramatsu, Hiroshi Yanagi, Toshio Kamiya, Masahiro Hirano, Noriaki Matsunami, Ken-ichi Shimizu, Hideo Hosono

  PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE 205 8 2007 - 2012 2008年08月 [査読有り][通常論文]
   

  Copper-based chalcogenide thin films deposited at room temperature were examined for exploring an active layer material for a p-channel thin film transistor (TFT) fabricable at room temperature. The electrical conductivities of chalcopyrite and simple copper chalcogenide thin films were controlled by introducing hydrogen sulfide and oxygen gases, respectively, during the film deposition. However, no current modulation by gate bias was observed in fabricated TFTs. Optical absorption spectra showed intense subgap absorptions, and these subgap states are thought to pin the Fermi levels. Although these copper-based chalcogenides did not work as TFT channels, we found that simple copper chalcogenides deposited under a high vacuum showed p-type degenerate conduction with a high conductivity up to 7.3 x 10(3) S/cm and a reasonably large work function of similar to 4.7 eV. These properties are rather favorable for a hole injection layer of flexible electronic devices and suggest a promising application as an anode layer in organic light emitting devices. 0 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
• Polyvalent-metal salts of heteropolyacid as efficient heterogeneous catalysts for Friedel-Crafts acylation of arenes with carboxylic acids

  Shimizu, Ken-ichi, Niimi, Kenjiro, Satsuma, Atsushi

  Catalysis Communications 9 6 2008年
• Polyvalent-metal salts of heteropolyacid as catalyst for Friedel-Crafts alkylation reactions

  Shimizu, Ken-ichi, Niimi, Kenjiro, Satsuma, Atsushi

  Applied Catalysis a-General 349 1-2 2008年
• Influence of hydrothermal aging on the catalytic activity of sulfated zirconia

  Busto, Mariana, Shimizu, Kiyoyuki, Vera, Carlos R., Grau, Javier M., Pieck, Carlos L., D'amato, Miguel A., Causa, M. T., Tovar, M.

  Applied Catalysis a-General 348 2 2008年
• Impedancemetric gas sensor based on Pt and WO(3) co-loaded TiO(2) and ZrO(2) as total NO(x) sensing materials

  Shimizu, Ken-ichi, Kashiwagi, Kohichi, Nishiyama, Hiroyuki, Kakimoto, Shiro, Sugaya, Satoshi, Yokoi, Hitoshi, Satsuma, Atsushi

  Sensors and Actuators B-Chemical 130 2 2008年
• Hydrogen sensor based on WO3 subnano-clusters and Pt co-loaded on ZrO2

  Shimizu, Ken-ichi, Chinzei, Isao, Nishiyama, Hiroyuki, Kakimoto, Shiro, Sugaya, Satoshi, Yokoi, Hitoshi, Satsuma, Atsushi

  Sensors and Actuators B-Chemical 134 2 2008年
• Effect of supports on formation and reduction rate of stored nitrates on NSR catalysts as investigated by in situ FT/IR

  Shimizu, Ken-ichi, Saito, Yoshinori, Nobukawa, Takeshi, Miyoshi, Naoto, Satsuma, Atsushi

  Catalysis Today 139 1-2 2008年
• Characterization of Lewis acidity of cation-exchanged montmorillonite K-10 clay as effective heterogeneous catalyst for acetylation of alcohol

  Shimizu, Ken-Ichi, Higuchi, Tomoya, Takasugi, Emi, Hatamachi, Tsuyoshi, Kodamab, Tatsuya, Satsuma, Atsushi

  Journal of Molecular Catalysis a-Chemical 284 1-2 2008年
• Agアルミナ触媒を用いた1級アルコールによる2級アルコールのβアルキル化

  佐藤 涼佑, 清水 研一, 薩摩 篤

  石油学会 年会・秋季大会講演要旨集 2008 30 - 30 公益社団法人 石油学会 2008年 

  アルキル化反応は通常、ハロゲン化アルキルを均一系の強塩基存在下で処理する量論反応で行われる。本研究では、不均一系触媒である銀アルミナが、1級アルコールによる2級アルコールのβアルキル化を効率的に進行させることを見いだした。本系は、アルコールの脱水素により生成するアルデヒドとケトンとのアルドール縮合と、縮合物の水素化がワンポットで進行し、βアルキル化生成物を収率96%で与える。
• スルホン酸樹脂を用いた単糖類の脱水によるHMF合成

  清水 研一, 魚住 梨江, 薩摩 篤

  石油学会 年会・秋季大会講演要旨集 2008 31 - 31 公益社団法人 石油学会 2008年 

  バイオマスの化学原料への変換の観点から、単糖類の脱水反応による5-ヒドロキシメチル-2-フルアルデヒド（HMF）合成が注目されているが、選択率の向上が課題である。本研究ではスルホン酸樹脂を触媒に用いて、フルクトースからHMFへの脱水反応の検討を行ったところ、HMFが100%収率で得られることを見いだした。さらに、スルホン酸樹脂と固体塩基を共存させることによりグルコースからHMFへの転換が効率的に進行することを見いだした。
• Formation and redispersion of silver clusters in Ag-MFI zeolite as investigated by time-resolved QXAFS and UV-vis

  Shimizu, Ken-ichi, Sugino, Kenji, Kato, Kazuo, Yokota, Shigeru, Okumura, Kazu, Satsuma, Atsushi

  Journal of Physical Chemistry C 111 4 1683 - 1688 2007年02月01日 [査読有り][通常論文]
  
• Reductive activation of O-2 with H-2-reduced silver clusters as a key step in the H-2-promoted selective catalytic reduction of NO with C3H8 over Ag/Al2O3

  Shimizu, Ken-ichi, Tsuzuki, Masao, Kato, Kazuo, Yokota, Shigeru, Okumura, Kazu, Satsuma, Atsushi

  Journal of Physical Chemistry C 111 2 2007年
• Reaction mechanism of H-2-promoted selective catalytic reduction of NO with NH3 over Ag/Al2O3

  Shimizu, Ken-ichi, Satsuma, Atsushi

  Journal of Physical Chemistry C 111 5 2007年
• Reaction mechanism of H-2-promoted selective catalytic reduction of NO with C3H8 over Ag-MFI zeolite

  Shimizu, Ken-ichi, Sugino, Kenji, Kato, Kazuo, Yokota, Shigeru, Okumura, Kazu, Satsuma, Atsushi

  Journal of Physical Chemistry C 111 17 2007年
• Promotion effect of hydrogen on lean NO, reduction by hydrocarbons over Ag/Al(2)O(3)catalyst

  Satokawa, Shigeo, Shibata, Junji, Shimizu, Ken-Ichi, Satsuma, Atsushi, Hattori, Tadashi, Kojima, Toshinori

  Chemical Engineering Science 62 18-20 2007年
• Polytungstate clusters on zirconia as a sensing material for a selective ammonia gas sensor

  Satsuma, Atsushi, Shimizu, Ken-ichi, Hattori, Tadashi, Nishiyama, Hiroyuki, Kakimoto, Shiro, Sugaya, Satoshi, Yokoi, Hitoshi

  Sensors and Actuators B-Chemical 123 2 2007年
• O-2-bridged multicopper(II) complex in zeolite for catalytic direct photo-oxidation of benzene to diphenols

  Shimizu, Ken-ichi, Maruyama, Rei, Hatamachi, Tsuyoshi, Kodama, Tatsuya

  Journal of Physical Chemistry C 111 17 2007年
• Mechanism of adsorptive removal of tert-butanethiol under ambient conditions with silver nitrate supported on silica and silica-alumina

  Shimizu, Ken-ichi, Komai, Shin-ichi, Kojima, Toshinori, Satokawa, Shigeo, Satsuma, Atsushi

  Journal of Physical Chemistry C 111 8 2007年
• Effects of hydrogen and oxygenated hydrocarbons on the activity and SO2-tolerance of Ag/Al2O3 for selective reduction of NO

  Shimizu, Ken-Ichi, Tsuzuki, Masao, Satsuma, Atsushi

  Applied Catalysis B-Environmental 71 1-2 2007年
• Effect of modified-alumina supports on propane-hydrogen-SCR over Ag/alumina

  Shimizu, K., Hashimoto, M., Shibata, J., Hattori, T., Satsuma, A.

  Catalysis Today 126 3-4 2007年
• Dicopper(II)-dioxygen complexes in Y zeolite for selective catalytic oxidation of cyclohexane under photoirradiation

  Shimizu, Ken-ichi, Murata, Yoshiaki, Satsuma, Atsushi

  Journal of Physical Chemistry C 111 51 2007年
• Artificial model of photosynthetic oxygen evolving complex: Catalytic O-2 production from water by di-mu-oxo manganese dimers supported by clay compounds

  Yagi, Masayuki, Narita, Komei, Maruyama, Syou, Sone, Koji, Kuwabara, Takayuki, Shimizu, Ken-ichi

  Biochimica Et Biophysica Acta-Bioenergetics 1767 6 2007年
• Ammonia sensing mechanism of tungstated-zirconia thick film sensor

  Satsuma, Atsushi, Shimizu, Ken-Ichi, Kashiwagi, Koichi, Endo, Tadanori, Nishiyama, Hiroyuki, Kakimoto, Shiro, Sugaya, Satoshi, Yokoi, Hitoshi

  Journal of Physical Chemistry C 111 32 2007年
• 銀/シリカアルミナ上でのチオールの吸着・脱硫機構

  清水 研一, 薩摩 篤

  石油学会 年会・秋季大会講演要旨集 2007 82 - 82 公益社団法人 石油学会 2007年 

  シリカアルミナ担持硝酸銀が常温でのt-ブチルメルカプタン(TBM)の吸着脱硫に有効であることを見いだした。反応中の吸着種、Ag種の挙動を、時間分解UV-vis、in situ IR、XAFSにより検討した。本系における常温脱硫は、銀イオンがメルカプタンと速やかに反応し、イソブテンとAg2Sクラスターを形成することにより進行することがわかった。
• 減圧下におけるイオン交換樹脂を用いたフルクトースの脱水反応

  魚住 梨江, 清水 研一, 薩摩 篤

  石油学会 年会・秋季大会講演要旨集 2007 189 - 189 公益社団法人 石油学会 2007年 

  フルクトースは再生可能資源として有用な化学原料である。先に我々は、フルクトースから5-ヒドロキシメチル-2-フルアルデヒド（HMF）への脱水反応が減圧下で行うことにより平衡論的に有利に進行することを見出した。DMSO溶媒中においてNafionを用いた時HMF収率97％が得られた。
• Ag触媒によるセルロースの分解反応

  古川 容竹, 清水 研一, 薩摩 篤

  石油学会 年会・秋季大会講演要旨集 2007 147 - 147 公益社団法人 石油学会 2007年 

  再生可能であるバイオマスを資源として利用するのは、地球温暖化防止に役立つとともに，持続的発展可能な循環型社会を形成していく上で重要な項目の一つである。バイオマスとしてはデンプンとセルロースがあり、植物の主成分であるセルロースは自然界に最も多く存在する化合物である。バイオマスとしてセルロースを利用できれば食料との競合を防ぐことも出来る。本研究ではAg触媒を用いて、セルロースの分解反応を行った。そして0.2MPaという低圧下において、セルロースの分解生成物が得られた。
• 銀イオン交換ゼオライトによる常温吸着脱硫

  里川 重夫, 清水 研一, 薩摩 篤

  ゼオライト 24 2 60 - 66 ゼオライト学会 2007年 [査読無し][通常論文]
  
• Selective catalytic reduction of NO over supported silver catalysts - practical and mechanistic aspects

  Shimizu, K, Satsuma, A

  Physical Chemistry Chemical Physics 8 23 2006年
• Pillaring of high charge density synthetic micas (Na-4-mica and Na-3-mica) by intercalation of oxides nanoparticles

  Shimizu, Ken-ichi, Nakamuro, Yumiko, Yamanaka, Ryoji, Hatamachi, Tsuyoshi, Kodama, Tatsuya

  Microporous and Mesoporous Materials 95 1-3 2006年
• Mechanistic study on adsorptive removal of tert-butanethiol on Ag-Y zeolite under ambient conditions

  Shimizu, Ken-ichi, Kobayashi, Nobumitsu, Satsuma, Atsushi, Kojima, Toshinori, Satokawa, Shigeo

  Journal of Physical Chemistry B 110 45 2006年
• Kinetic and in situ infrared studies on SCR of NO with propane by silver-alumina catalyst: Role of H-2 on O-2 activation and retardation of nitrate poisoning

  Shimizu, K, Shibata, J, Satsuma, A

  Journal of Catalysis 239 2 2006年
• Effect of hydrogen addition on SO2 tolerance of silver-alumina for SCR of NO with propane

  Shimizu, K, Higashimata, T, Tsuzuki, M, Satsuma, A

  Journal of Catalysis 239 1 2006年
• Characterization and activity analysis of catalytic water oxidation induced by hybridization of [(OH2)(terpy)Mn(mu-O)(2)Mn(terpy)(OH2)](3+) and clay compounds

  Narita, Komei, Kuwabara, Takayuki, Sone, Koji, Shimizu, Ken-ichi, Yagi, Masayuki

  Journal of Physical Chemistry B 110 46 2006年
• Pillaring of Ruddlesden-Popper perovskite tantalates, H(2)ATa(2)O(7) (A = Sr or La-2/3), with n-alkylamines and oxide nanoparticles

  KI Shimizu, S Itoh, T Hatamachi, Y Kitayama, T Kodama

  JOURNAL OF MATERIALS CHEMISTRY 16 8 773 - 779 2006年 [査読有り][通常論文]
   

  The Ruddlesden-Popper-type layered perovskite tantalates, H(2)ATa(2)O(7) (A = Sr or La-2/3), were pillared with n-alkylamines and oxide nanoparticles for the first time. H2SrTa2O7 can accommodate n-alkylamines (carbon numbers = 4, 8, 12, 16) to form intercalation compounds. A linear relationship is observed between the interlayer distance and the number of carbon atoms in n-alkyl chains, indicating the formation of a bilayer of the n-alkylamines. Porous metal oxides were synthesized by pillaring the n-octylamine intercalated H(2)ATa(2)O(7) perovskites with Fe2O3 or Fe-Si mixed oxide (FeSi). These materials were well characterized by XRD, TEM, N-2 adsorption, and Fe K-edge XAFS (XANES and EXAFS). FeSi pillared H2SrTa2O7 and H2La2/3Ta2O7 have a high surface area (52 and 130 m(2) g(-1)) and microporosity. Fe2O3 pillared H2SrTa2O7 has a macroporous structure with a relatively low surface area (14 m(2) g(-1)). XAFS analysis reveals that the Fe species in FeSi pillared perovskites are tetrahedral Fe3+ species incorporated in a silica matrix or highly dispersed on silica particles, while those in the Fe2O3 pillared one are alpha-Fe2O3 nanoparticles. The acidic property is tested by temperature programmed desorption (TPD) of ammonia, and the result shows that pillaring increases the number of acid sites in perovskites.
• ディーゼルNOx還元触媒として注目されるAgアルミナ触媒

  清水 研一, Shimizu Kenichi, 薩摩 篤, Satsuma Atsushi

  化学 61 5 64 - 65 化学同人 2006年 [査読無し][通常論文]
  
• 固体酸を感応層とする抵抗型アンモニアセンサ

  触媒 48 544  2006年 [査読無し][通常論文]
  
• Photocatalytic water splitting on Ni-intercalated Ruddlesden-Popper tantalate H2La2/3Ta2O7

  Shimizu, K, Itoh, S, Hatamachi, T, Kodama, T, Sato, M, Toda, K

  Chemistry of Materials 17 20 2005年
• Michael reaction of beta-ketoesters with vinyl ketones by iron(III)-exchanged fluorotetrasilicic mica: catalytic and spectroscopic studies

  Shimizu, K, Miyagi, M, Toshiki, K, Hatamachi, T, Kodama, T, Kitayama, Y

  Journal of Catalysis 229 2 2005年
• Degradation of hydrophobic organic pollutants by titania pillared fluorine mica as a substrate specific photocatalyst

  Shimizu, K, Murayama, H, Nagai, A, Shimada, A, Hatamachi, T, Kodama, T, Kitayama, Y

  Applied Catalysis B-Environmental 55 2 2005年
• Ag clusters as active species for HC-SCR over Ag-zeolites

  Satsuma, A, Shibata, J, Shimizu, K, Hattori, T

  Catalysis Surveys From Asia 9 2 2005年
• Acidic properties of sulfonic acid-functionalized FSM-16 mesoporous silica and its catalytic efficiency for acetalization of carbonyl compounds

  Shimizu, K, Hayashi, E, Hatamachi, T, Kodama, T, Higuchi, T, Satsuma, A, Kitayama, Y

  Journal of Catalysis 231 1 2005年
• Sustainable transesterification of beta-ketoesters catalyzed by amine grafted on silica gel

  H Hagiwara, A Koseki, K Isobe, K Shimizu, T Hoshi, T Suzuki

  SYNLETT 12 2188 - 2190 2004年10月 [査読有り][通常論文]
   

  Transesterification of beta-ketoesters with various alcohols has been effected by N,N-diethylaminopropylated silica gel (NDEAP) as a catalyst in refluxing xylene. Generality of the reaction was demonstrated by successful transesterification of olefinic alcohols, tertiary alcohols and alcohols having acid- or base-sensitive substituents. The catalyst has been efficiently recycled more than five times without any re-activation.
• Ni/ceramic/molten-salt composite catalyst with high-temperature thermal storage for use in solar reforming processes

  T Kodama, Y Isobe, Y Kondoh, S Yamaguchi, KI Shimizu

  ENERGY 29 5-6 895 - 903 2004年04月 [査読有り][通常論文]
   

  Composite materials of catalytically activated porous ceramics with molten salts were proposed for use in solar thermochemical reforming processes of methane as catalyst with high-temperature thermal storage. The high heat capacity and large latent heat (heat of solidification) of the composite molten salt at high temperatures are expected to circumvent the rapid temperature change of the catalyst bed under fluctuation of insolation. The composite catalysts of Ni-activated porous ceramics (mm-sized alumina or zirconia balls) with an alkali-metal chloride or carbonate (NaCl or Na2CO3) were prepared and examined for the activity and stability for CO2 reforming of methane. (C) 2003 Elsevier Ltd. All rights reserved.
• Ultrafine na-4-mica: Uptake of alkali and alkaline earth metal cations by ion exchange

  Kodama, T, Ueda, M, Nakamuro, Y, Shimizu, K, Komarneni, S

  Langmuir 20 12 2004年
• Structure of active Ag clusters in Ag zeolites for SCR of NO by propane in the presence of hydrogen

  Shibata, J, Shimizu, K, Takada, Y, Shichia, A, Yoshida, H, Satokawa, S, Satsuma, A, Hattori, T

  Journal of Catalysis 227 2 2004年
• Structural investigations of functionalized mesoporous silica-supported palladium catalyst for Heck and Suzuki coupling reactions

  Shimizu, K, Koizumi, S, Hatamachi, T, Yoshida, H, Komai, S, Kodama, T, Kitayama, Y

  Journal of Catalysis 228 1 2004年
• SO3H-functionalized silica for acetalization of carbonyl compounds with methanol and tetrahydropyranylation of alcohols

  Shimizu, K, Hayashi, E, Hatamachi, T, Kodama, T, Kitayama, Y

  Tetrahedron Letters 45 26 2004年
• Selective photo-oxidation of benzene over transition metal-exchanged BEA zeolite

  Shimizu, K, Akahane, H, Kodama, T, Kitayama, Y

  Applied Catalysis a-General 269 1-2 2004年
• Photocatalytic water splitting on hydrated layered perovskite tantalate A(2)SrTa(2)O(7)center dot nH(2)O ( A = H, K, and Rb)

  Shimizu, K, Tsuji, Y, Hatamachi, T, Toda, K, Kodama, T, Sato, M, Kitayama, Y

  Physical Chemistry Chemical Physics 6 5 2004年
• Pd-sepiolite catalyst for Suzuki coupling reaction in water: Structural and catalytic investigations

  Shimizu, K, Maruyama, R, Komai, S, Kodama, T, Kitayama, Y

  Journal of Catalysis 227 1 2004年
• Factors controlling activity and selectivity for SCR of NO by hydrogen over supported platinum catalysts

  Shibata, J, Hashimoto, M, Shimizu, K, Yoshida, H, Hattori, T, Satsuma, A

  Journal of Physical Chemistry B 108 47 2004年
• Alkaline earth cation exchange with novel Na-3-mica: kinetics and thermodynamic selectivities

  Shimizu, K, Hasegawa, K, Nakamuro, Y, Kodama, T, Komarneni, S

  Journal of Materials Chemistry 14 6 2004年
• Promotion of HC-SCR Activity of Ag/Alumina Catalyst by Controlling Reaction Field

  Satsuma Atsushi, Shibata Junji, Shimizu Ken-ichi, Yoshida Hisao, Hattori Tadashi

  アジア・太平洋化学工学会議発表論文要旨集 2004 121 - 121 公益社団法人 化学工学会 2004年 

  This paper reports promotion effect of HC-SCR activity of Ag/Al₂O₃ catalyst by the control of reaction atmospheres, i.e., (1) the use of higher hydrocarbons as reductants, (2) co-feeding of water vapour, and (3) co-feeding of small amount of hydrogen. Although Ag/Al₂O₃ was not active for propane-SCR below 623 K, the conversions of NO to N₂ were above 65 % when n-octane was used. Co-feeding of water vapour resulted in nearly 100 % NO conversion in the SCR by n-octane, which may be because of the suppression of the poisoning by carbonaceous deposits. In the case of SCR by lower alkanes at lower temperatures, it was clarified that the co-feeding of small amount of hydrogen is effective. The promotion effect of hydrogen is caused by the modification of Ag species on alumina, i.e., Ag⁺ species was reduced and agglomerated by hydrogen into Ag cluster, which is active for the SCR reaction. These effects of reaction atmospheres are discussed from a point of view of surface reaction pathway and dynamics of active species measured by in-situ FT/IR and in-situ UV-Vis spectra.
• NO選択還元反応における飛躍的な性能向上―銀系触媒における水素の添加効果―

  清水 研一, 柴田 順二, 里川 重夫

  表面 42 9 12 - 275 広信社 2004年 [査読無し][通常論文]
  
• Sustainable self-aldol condensation of unmodified aldehyde: A combination of ionic liquid and heterogeneous secondary-amine grafted on silica

  Hamaya, J, Suzuki, T, Hoshi, T, Shimizu, K, Kitayama, Y, Hagiwara, H

  Synlett 6 2003年
• Stepwise production of CO-rich syngas and hydrogen via methane reforming by a WO3-redox catalyst

  Kodama, T, Shimizu, T, Satoh, T, Shimizu, KI

  Energy 28 11 2003年
• Seasonal change of persistent organic pollutant concentrations in air at Niigata area, Japan

  Murayama, H, Takase, Y, Mitobe, H, Mukai, H, Ohzeki, T, Shimizu, K, Kitayama, Y

  Chemosphere 52 4 2003年
• Promotion effect of hydrogen on surface steps in SCR of NO by propane over alumina-based silver catalyst as examined by transient FT-IR

  Shibata, J, Shimizu, K, Satokawa, S, Satsuma, A, Hattori, T

  Physical Chemistry Chemical Physics 5 10 2003年
• Promotion effect of H-2 on the low temperature activity of the selective reduction of NO by light hydrocarbons over Ag/Al2O3

  Satokawa, S, Shibata, J, Shimizu, K, Atsushi, S, Hattori, T

  Applied Catalysis B-Environmental 42 2 2003年
• Persistent organic pollutants in rain at Niigata, Japan

  Takase, Y, Murayama, H, Mitobe, H, Aoki, T, Yagoh, H, Shibuya, N, Shimizu, K, Kitayama, Y

  Atmospheric Environment 37 29 2003年
• Novel Na-3-mica: Alkaline earth cation exchange and immobilization

  Kodama, T, Hasegawa, K, Shimizu, K, Komarneni, S

  Separation Science and Technology 38 3 2003年
• Ni-Mg-O catalyst driven by direct light irradiation for catalytically-activated foam absorber in a solar reforming receiver-reactor

  Kodama, T, Kiyama, A, Moriyama, T, Yokoyama, T, Shimizu, KI, Andou, H, Satou, N

  Energy & Fuels 17 4 2003年
• In situ FT/IR study of selective catalytic reduction of NO over alumina-based catalysts

  Satsuma, A, Shimizu, K

  Progress in Energy and Combustion Science 29 1 2003年
• Fe3+-exchanged fluorotetrasilicic mica as an active and reusable catalyst for Michael reaction

  Shimizu, K, Miyagi, M, Kan-no, T, Kodama, T, Kitayama, Y

  Tetrahedron Letters 44 40 2003年
• Evaluation of activated carbon fiber filter for sampling of organochlorine pesticides in environmental water samples

  Murayama, H, Moriyama, N, Mitobe, H, Mukai, H, Takase, Y, Shimizu, KI, Kitayama, Y

  Chemosphere 52 5 2003年
• Catalytically activated metal foam absorber for light-to-chemical energy conversion via solar reforming of methane

  Kodama, T, Kiyama, A, Shimizu, KI

  Energy & Fuels 17 1 2003年
• 7-5.吸熱触媒反応による高温太陽熱/水素エネルギー転換((2)太陽エネルギー,Session 7 新エネルギー)

  児玉 竜也, 清水 研一

  日本エネルギー学会大会講演要旨集 12 324 - 325 一般社団法人日本エネルギー学会 2003年
• Catalytic direct 1,4-conjugate addition of aldehydes to vinylketones on N-methyl-3-Aminopropylated FSM-16

  K Shimizu, H Suzuki, T Kodama, H Hagiwara, Y Kitayama

  SCIENCE AND TECHNOLOGY IN CATALYSIS 2002 145 145 - 148 2003年 [査読有り][通常論文]
   

  Direct 1,4-conjugate addition of naked aldehydes to vinylketones is catalysed effectively by N-metlyl-3-aminopropylated FSM-16 mesoporous silica. This reaction is regarded as a novel heterogeneous catalysis for a practical and environmentally friendly C-C bond formation reaction.
• Kinetics of metal oxide-catalyzed CO2 gasification of coal in a fluidized-bed reactor for solar thermochemical process. (vol 15, pg 1200, 2001)

  T Kodama, A Funatoh, K Shimizu, Y Kitayama

  ENERGY & FUELS 16 3 802 - 802 2002年05月 [査読有り][通常論文]
  
• Synthesis of novel Na-rich mica and selective strontium ion exchange and fixation

  Kodama, T, Nagai, S, Hasegawa, K, Shimizu, K, Komarneni, S

  Separation Science and Technology 37 8 2002年
• Suzuki cross-coupling reaction catalyzed by palladium-supported sepiolite

  Shimizu, K, Kan-no, T, Kodama, T, Hagiwara, H, Kitayama, Y

  Tetrahedron Letters 43 32 2002年
• Stereoselective hydrogenation of linoleic acid over Ir/FSM-16 catalyst

  Shimizu, K, Kan-no, T, Hatamachi, T, Komai, S, Kodama, T, Kitayama, Y

  Applied Catalysis a-General 228 1-2 2002年
• Stepwise production of CO-RICH syngas and hydrogen via solar methane reforming by using a Ni(II)-ferrite redox system

  Kodama, T, Shimizu, T, Satoh, T, Nakata, M, Shimizu, KI

  Solar Energy 73 5 2002年
• Self-aldol condensation of unmodified aldehydes secondary-amine immobilised in FSM-16 catalysed by silica

  Shimizu, K, Hayashi, E, Inokuchi, T, Kodama, T, Hagiwara, H, Kitayama, Y

  Tetrahedron Letters 43 50 2002年
• Selective oxidation of liquid hydrocarbons over photoirradiated TiO2 pillared clays

  Shimizu, KI, Kaneko, T, Fujishima, T, Kodama, T, Yoshida, H, Kitayama, Y

  Applied Catalysis a-General 225 1-2 2002年
• Photocatalytic water splitting over spontaneously hydrated layered tantalate A(2)SrTa(2)O(7)center dot nH(2)O (A=H,K,Rb)

  Shimizu, K, Tsuji, Y, Kawakami, M, Toda, K, Kodama, T, Sato, M, Kitayama, Y

  Chemistry Letters 11 2002年
• Photocatalytic degradation of hexachlorocyclohexane (HCH) by TiO2-pillared fluorine mica

  Murayama, F, Shimizu, K, Tsukada, N, Shimada, A, Kodama, T, Kitayama, Y

  Chemical Communications 22 2002年
• Nickel catalyst driven by direct light irradiation for solar CO2-reforming of methane

  Kodama, T, Ohtake, H, Shimizu, KI, Kitayama, Y

  Energy & Fuels 16 5 2002年
• Influence of hydrocarbon structure on selective catalytic reduction of NO by hydrocarbons over Cu-Al2O3

  Shibata, J, Shimizu, K, Satsuma, A, Hattori, T

  Applied Catalysis B-Environmental 37 3 2002年
• Fluidized bed coal gasification with CO2 under direct irradiation with concentrated visible light

  Kodama, T, Kondoh, Y, Tamagawa, T, Funatoh, A, Shimizu, KI, Kitayama, Y

  Energy & Fuels 16 5 2002年
• Conjugate addition of unmodified aldehydes: recycle of heterogeneous amine catalyst and ionic liquid

  Hagiwara, H, Sayuri, T, Okabe, T, Hoshi, T, Suzuki, T, Suzuki, H, Shimizu, K, Kitayama, Y

  Green Chemistry 4 5 2002年
• Catalytic direct 1,4-conjugate addition of aldehydes to vinylketones on secondary-amines immobilised in FSM-16 silica

  Shimizu, K, Suzuki, H, Hayashi, E, Kodama, T, Tsuchiya, Y, Hagiwara, H, Kitayama, Y

  Chemical Communications 10 2002年
• シンプルな有機分子触媒によるシンプルかつクリーンな炭素－炭素結合生成反応

  清水 研一

  触媒 44 8 601 - 603 触媒学会 2002年 [査読無し][通常論文]
  
• Thermochemical methane reforming using WO3 as an oxidant below 1173 K by a solar furnace simulator

  Shimizu, T, Shimizu, K, Kitayama, Y, Kodama, T

  Solar Energy 71 5 2001年
• Synthesis of Na-2-mica from metakaolin and its cation exchange properties

  Kodama, T, Higuchi, T, Shimizu, T, Shimizu, K, Komarneni, S, Hoffbauer, W, Schneider, H

  Journal of Materials Chemistry 11 8 2001年
• Sol-gel prepared Sn-Al2O3 catalysts for the selective reduction of NO with propene

  Haneda, M, Ohzu, S, Kintaichi, Y, Shimizu, K, Shibata, J, Yoshida, H, Hamada, H

  Bulletin of the Chemical Society of Japan 74 11 2001年
• Silver-alumina catalysts for selective reduction of NO by higher hydrocarbons: structure of active sites and reaction mechanism

  Shimizu, K, Shibata, J, Yoshida, H, Satsuma, A, Hattori, T

  Applied Catalysis B-Environmental 30 1-2 2001年
• Selective exchange and fixation of strontium ions with ultrafine Na-4-mica

  Kodama, T, Harada, Y, Ueda, M, Shimizu, K, Shuto, K, Komarneni, S

  Langmuir 17 16 2001年
• Quantification of aluminium coordinations in alumina and silica-alumina by AlK-edge XANES

  Kato, Y, Shimizu, K, Matsushita, N, Yoshida, T, Yoshida, H, Satsuma, A, Hattori, T

  Physical Chemistry Chemical Physics 3 10 2001年
• Mechanistic causes of the hydrocarbon effect on the activity of Ag-Al2O3 catalyst for the selective reduction of NO

  Shimizu, K, Shibata, J, Satsuma, A, Hattori, T

  Physical Chemistry Chemical Physics 3 5 2001年
• Ligand field effect on the chemical shift in XANES spectra of Cu(II) compounds

  Shimizu, K, Maeshima, H, Yoshida, H, Satsuma, A, Hattori, T

  Physical Chemistry Chemical Physics 3 5 2001年
• Kinetics of metal oxide-catalyzed CO2 gasification of coal in a fluidized-bed reactor for solar thermochemical process

  Kodama, T, Funatoh, A, Shimizu, K, Kitayama, Y

  Energy & Fuels 15 5 2001年
• Crystal-size control and characterization of Na-4-mica prepared from kaolinite

  Kodama, T, Harada, Y, Ueda, M, Shimizu, K, Shuto, K, Komarneni, S, Hoffbauer, W, Schneider, H

  Journal of Materials Chemistry 11 4 2001年
• Intermediates in the selective reduction of NO by propene over Cu-Al2O3 catalysts: Transient in-situ FTIR study

  K Shimizu, H Kawabata, H Maeshima, A Satsuma, T Hattori

  JOURNAL OF PHYSICAL CHEMISTRY B 104 13 2885 - 2893 2000年04月 [査読有り][通常論文]
   

  The mechanism of the selective catalytic reduction (SCR) of NO by C3H6 On CU-Al2O3 catalysts, which consist of highly dispersed Cu2+ ions in the surface aluminate phase, are investigated by in-situ FTIR spectroscopy. During NO + C3H6 + O-2 reaction, the acetate is produced via the partial oxidation of C3H6 and becomes the predominant adspecies in the steady-state condition at 473-623 K. The acetate, which is stable in NO, is quite reactive with NO + O-2, leading to the formation of isocyanate species (Cu-NCO) on the surface and N-2 and CO2 in the gas phase. The rate of acetate reaction in NO + O-2 is close to the steady-state fate of NO reduction over wide range of temperature, indicating that the acetate is an intermediate in the SCR and takes part in the rate-determining stage. A mechanism is proposed; the acetate and nitrates, formed by NO + O-2, react to generate the Cu-NCO species, then Cu-NCO reacts with nitrates or NO to produce N-2 and CO2. This mechanism explains the role of oxygen in facilitating SCR. Cu2+ ion is the principal active component in Cu-Al2O3 catalysts; it plays crucial roles in all the important steps, including the reaction of the acetate with nitrates.
• Crystal field effect on the chemical shift in Cu L-III XANES spectra of Cu(II) compounds

  K Shimizu, H Maeshima, H Yoshid, A Satsuma, T Hattori

  CHEMISTRY LETTERS 3 210 - 211 2000年03月 [査読有り][通常論文]
   

  Chemical shifts of the 2p(3/2) --> 3d peaks in the Cu L-III XANES spectra of copper(II) compounds were correlated with the crystal field parameter, 10Dq, and were understood in terms of the simple crystal field concept.
• Spectroscopic characterisation of Cu-Al2O3 catalysts for selective catalytic reduction of NO with propene

  Shimizu, K, Maeshima, H, Yoshida, H, Satsuma, A, Hattori, T

  Physical Chemistry Chemical Physics 2 10 2000年
• Mechanism of NO reduction by CH4 in the presence of O-2 over Pd-H-mordenite

  Shimizu, K, Okada, F, Nakamura, Y, Satsuma, A, Hattori, T

  Journal of Catalysis 195 1 2000年
• Catalytic performance of Ag-Al2O3 catalyst for the selective catalytic reduction of NO by higher hydrocarbons

  Shimizu, K, Satsuma, A, Hattori, T

  Applied Catalysis B-Environmental 25 4 2000年
• Molecular basis for the design of transition-metal oxide catalysts for selective catalytic reduction of NO by hydrocarbons

  K. Shimizu, H. Maeshima, H. Kawabata, H. Yoshida, A. Satsuma, T. Hattori

  Stud. Surf. Sci. Catal. 130 1403 - 1408 2000年 [査読有り][通常論文]
  
• Metal oxide catalysts for selective reduction of NOx by hydrocarbons: toward molecular basis for catalyst design

  K Shimizu, A Satsuma, T Hattori

  CATALYSIS SURVEYS FROM JAPAN 4 2 115 - 123 2000年 [査読有り][通常論文]
   

  Metal oxides are stable and highly durable catalysts for the selective catalytic reduction (SCR) of NO by hydrocarbons and potential candidates for practical use. This review focuses on the development as well as the fundamental understanding of metal oxide based catalysts for selective reduction of NO by hydrocarbons. Our studies on the SCR-deNOx properties of Ga2O3/Al2O3, Cu-Al2O3, and Ag-Al2O3 catalysts are presented and it is attempted to demonstrate the advantages of this type of catalysts. On the basis of several spectroscopic characterizations, the effect of important factors, such as dispersion, coordination, and the electronic states of the metal cation, on the intrinsic catalytic activity are quite well clarified. From the in situ FTIR results, the reaction mechanism is understood in terms of formation and reaction of surface molecules. The structural and kinetic information obtained at the molecular level provides a useful strategy for designing better deNOx catalysts using metal oxides.
• Role of acetate and nitrates in the selective catalytic reduction of NO by propene over alumina catalyst as investigated by FTIR

  K Shimizu, H Kawabata, A Satsuma, T Hattori

  JOURNAL OF PHYSICAL CHEMISTRY B 103 25 5240 - 5245 1999年06月 [査読有り][通常論文]
   

  The mechanism of the selective catalytic reduction (SCR) of NO by C3H6 On Al2O3 was investigated using in situ IR spectroscopy. Attention was focused on the reactivity of the adsorbed acetate and nitrates on the Al2O3 surface. IR spectra showed that the reaction starts with the nitrates formation from NO + O-2 followed by its reaction with C3H6 to form acetate, which becomes the predominant surface species in the steady-state condition. The acetate band, which was stable in He or NO, significantly decreased when the flowing gas was switched to NO + O-2 A complementary set of experiments monitoring gas composition showed that N-2 and COx were produced by the reaction of acetate with NO + Oz. The rate of acetate consumption in NO + O-2 exhibited the same order of magnitude as the NO reduction rate, indicating that the acetate is active as a reductant and takes part in the N-2 formation. Nitrates can oxidize both C3H6 and acetate, and are mostly reduced to N-2. A proposed reaction scheme explains the role of O-2 in facilitating SCR of NO.
• Alumina-supported gallium oxide catalysts for NO selective reduction: Influence of the local structure of surface gallium oxide species on the catalytic activity

  K Shimizu, M Takamatsu, K Nishi, H Yoshida, A Satsuma, T Tanaka, S Yoshida, T Hattori

  JOURNAL OF PHYSICAL CHEMISTRY B 103 9 1542 - 1549 1999年03月 [査読有り][通常論文]
   

  The surface structure of alumina-supported gallium oxide catalysts for selective catalytic reduction of NO by CH4 was studied. The XPS results showed that Ga atoms were dispersed well over the Al2O3 surface for the samples with Ga2O3 content below monolayer coverage (27 wt %) and that Ga2O3 particles appeared at higher content. The XANES and EXAFS results revealed that, below monolayer coverage, Ga atoms were located at the surface cation sites (tetrahedral and octahedral) of Al2O3, and the fraction of tetrahedral Ga species decreased as Ga content increased. The activity per surface area of the catalysts increased with Ga2O3 content up to around the monolayer coverage and declined at higher content. Below monolayer coverage, the activity per exposed Ga atom decreased as Ga content increased, which correlated well with the change in the fraction of tetrahedral Ga species. It was concluded that the present reaction is a structure-sensitive reaction depending on the local structure of Ga atom; GaO4 tetrahedra highly dispersed in the surface spinel are responsible for the activity.
• Enhanced De-NOx performance of Ag-Al2O3 catalyst by increasing carbon number of hydrocarbon reductants

  Shimizu, K, Shibata, J, Satsuma, A, Hattori, T

  Chemistry Letters 10 1999年
• Deconvolution analysis of Cu L-edge XANES for quantification of copper (II) coordinations in copper-aluminate catalysts

  Shimizu, K, Maeshima, H, Yoshida, H, Satsuma, A, Hattori, T

  Japanese Journal of Applied Physics Part 1-Regular Papers Short Notes & Review Papers 38 1999年
• AlK-edge XANES study for the quantification of aluminium coordinations in alumina

  Shimizu, K, Kato, Y, Yoshida, T, Yoshida, H, Satsuma, A, Hattori, T

  Chemical Communications 17 1999年
• Deconvolution analysis of Ga K-edge XANES for quantification of gallium coordinations in oxide environments

  K Nishi, K Shimizu, M Takamatsu, H Yoshida, A Satsuma, T Tanaka, S Yoshida, T Hattori

  JOURNAL OF PHYSICAL CHEMISTRY B 102 50 10190 - 10195 1998年12月 [査読有り][通常論文]
   

  A quantitative analysis of gallium species (GaO4 tetrahedra and GaO6 octahedra) by means of X-ray absorption spectroscopy (XANES and EXAFS) at the Ga K-edge was performed on a series of gallium oxides with various phases and SiO2-supported ones. XANES spectra of gallium oxides showed two distinguishable peaks that were assigned to tetrahedral and octahedral gallium oxide species on the basis of a comparison with those of reference compounds. A deconvolution analysis of XANES spectra was carried out on the assumption that the absorption due to each species is expressed by a set of Gaussian and arctangent functions, and the tetrahedral/octahedral ratios were quantitatively estimated from the ratio of the peak areas. By the EXAFS curve-fitting analysis, the tetrahedral/octahedral ratios were also estimated, and they were in good agreement with those obtained by XANES analysis. It was concluded that the Ga atoms with a different coordination symmetry (tetrahedral or octahedral) can be estimated quantitatively by a deconvolution analysis of XANES.
• Transition metal-aluminate catalysts for NO reduction by C3H6

  Shimizu, K, Maeshima, H, Satsuma, A, Hattori, T

  Applied Catalysis B-Environmental 18 1-2 1998年
• Selective catalytic reduction of NO by hydrocarbons on Ga2O3/Al2O3 catalysts

  Shimizu, K, Satsuma, A, Hattori, T

  Applied Catalysis B-Environmental 16 4 1998年
• Selective catalytic reduction of nitrogen oxides with hydrocarbons over Zn-Al-Ga complex oxides

  Okimura, Y, Yokoi, H, Ohbayashi, K, Shimizu, K, Satsuma, A, Hattori, T

  Catalysis Letters 52 3-4 1998年
• Reactivity of surface nitrate species in the selective reduction of NO with propene over Na-H-mordenite as investigated by dynamic FTIR spectroscopy

  Satsuma, A, Enjoji, T, Shimizu, K, Sato, K, Yoshida, H, Hattori, T

  Journal of the Chemical Society-Faraday Transactions 94 2 1998年
• Formation and reaction of surface acetate on Al2O3 during NO reduction by C3H6

  Shimizu, K, Kawabata, H, Satsuma, A, Hattori, T

  Applied Catalysis B-Environmental 19 2 1998年
• Catalyst effectiveness factor of cobalt-exchanged mordenites for the selective catalytic reduction of NO with hydrocarbons

  Shichi, A, Satsuma, A, Iwase, M, Shimizu, K, Komai, S, Hattori, T

  Applied Catalysis B-Environmental 17 1-2 1998年
• Low-temperature selective reduction of NO with propene over alkaline-exchanged mordenites

  Satsuma, A, Yamada, K, Sato, K, Shimizu, K, Hattori, T, Murakami, Y

  Catalysis Letters 45 3-4 1997年
• Influence of local structure on the catalytic activity of gallium oxide for the selective reduction of NO by CH4

  Shimizu, K, Takamatsu, M, Nishi, K, Yoshida, H, Satsuma, A, Hattori, T

  Chemical Communications 15 1827 - 1828 1996年 [査読有り][通常論文]
  
• Unique catalytic behavior of alkaline-exchanged mordenites in reduction of NO with C3H6 at low temperature

  A Satsuma, K Yamada, K Shimizu, K Sato, T Hattori, Y Murakami

  ENVIRONMENTAL CATALYSIS 112 335 - 338 1995年 [査読有り][通常論文]
  

書籍

• データ駆動型材料開発 : オントロジーとマイニング、計測と実験装置の自動制御

  船津, 公人 
  エヌ・ティー・エス 2021年11月 (ISBN: 9784860437596) 3, 6, 244, 6, 図版26p
• 「環境触媒ハンドブック」, 岩本正和監修, 酸化物マトリックスを利用したNO選択還元触媒の設計

  エヌ・ティー・エス 2001年

講演・口頭発表等

• 計算材料設計最前線2021 理論計算とセラミックス触媒担体設計-多様な表面の特性計算-

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  セラミックス 2021年
• 理論化学・データ科学を利用した固体触媒の研究・開発を目指して

  清水研一, 日沼洋陽, 蒲池高志

  日本物理学会講演概要集(CD-ROM) 2021年
• CHAゼオライト内Inヒドリドの局所構造解析とエタン脱水素触媒作用

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  日本化学会春季年会講演予稿集(Web) 2021年
• O₂共存下におけるCO₂吸蔵・還元的有効利用反応に有用な二元機能触媒の開発

  宮崎眞太, WU Ziyang, 今健一, 鳥屋尾隆, 鳥屋尾隆, 前野禅, 清水研一, 清水研一

  触媒討論会講演予稿集(CD-ROM) 2021年
• CHAゼオライト内Pdカチオンの局所構造とNO吸着脱離特性

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• ゼオライト内Gaヒドリド種の構造制御による選択的エタン脱水素触媒の開発

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  触媒討論会講演予稿集(CD-ROM) 2021年
• W置換V₂O₅触媒による低温・水蒸気雰囲気下でのNH₃-SCRと反応機構解析

  猪股雄介, 清永英嗣, 盛田啓一郎, 吉田和広, 窪田博愛, 鳥屋尾隆, 清水研一, 春田正毅, 村山徹, 村山徹

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• H-CHA上での室温アンモニア脱硝

  清水研一, 安村駿作, LIU Chong, 鳥屋尾隆, 前野禅

  触媒討論会講演予稿集(CD-ROM) 2021年
• 金属間化合物中の孤立Ptサイトを用いた高効率プロパン脱水素

  中谷勇希, 山添誠司, 山添誠司, 山添誠司, 清水研一, 清水研一, 古川森也, 古川森也, 古川森也

  触媒討論会講演予稿集(CD-ROM) 2021年
• CHAゼオライト内Inヒドリドを触媒活性点とする選択的エタン脱水素反応

  安村駿作, WU Xiaopeng, CHONG Liu, 鳥屋尾隆, 鳥屋尾隆, 前野禅, 清水研一, 清水研一

  触媒討論会討論会A予稿集(CD-ROM) 2020年
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  触媒討論会討論会A予稿集(CD-ROM) 2020年
• Cuイオン交換ゼオライト結晶内におけるNOの拡散機構

  九嶋恵伍, 中坂佑太, 清水研一, 柴田元, 増田隆夫

  ゼオライト研究発表会講演予稿集 2020年
• 擬二元系合金の構築によるMCH脱水素触媒の高性能化

  中谷勇希, 清水研一, 清水研一, 古川森也, 古川森也, 古川森也

  触媒討論会講演予稿集(CD-ROM) 2020年
• Nb₂O₅を触媒に用いるアミドのカルボン酸への加水分解

  SIDDIKI S.M.A. Hakim, RASHED M d. Nurnobi, SULTANA Touchy Abeda, 鳥屋尾隆, 清水研一, 清水研一

  触媒討論会講演予稿集(CD-ROM) 2020年
• 150°C以下でNH₃-SCR活性を示すバルク酸化バナジウム触媒

  猪股雄介, 秦慎一, 清永英嗣, 盛田啓一郎, 吉田和広, 窪田博愛, 鳥屋尾隆, 清水研一, 春田正毅, 村山徹

  触媒討論会講演予稿集(CD-ROM) 2020年
• β-Ga₂O₃およびθ-Al₂O₃の多終端における表面酸素脱着エネルギーの第一原理計算

  日沼洋陽, 日沼洋陽, 鳥屋尾隆, 鳥屋尾隆, 蒲池高志, 蒲池高志, 濱本信次, 清水研一, 清水研一

  触媒討論会講演予稿集(CD-ROM) 2020年
• インジウム交換CHAゼオライト内で生成するヒドリド種の構造と脱水素触媒作用

  前野禅, 安村駿作, WU Xiaopeng, LIU Chong, 鳥屋尾隆, 鳥屋尾隆, 清水研一, 清水研一

  触媒討論会講演予稿集(CD-ROM) 2020年
• 機械学習を用いたメタン酸化カップリング反応の文献データ解析と新規触媒予測

  鳥屋尾隆, 鳥屋尾隆, 高尾基史, 前野禅, 高草木達, 瀧川一学, 瀧川一学, 清水研一, 清水研一

  触媒討論会講演予稿集(CD-ROM) 2020年
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  日沼洋陽, 日沼洋陽, 鳥屋尾隆, 鳥屋尾隆, 蒲池高志, 蒲池高志, 前野禅, 高草木達, 古川森也, 古川森也, 瀧川一学, 瀧川一学, 清水研一, 清水研一

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  清水 研一, 後藤 文倫, 鳥屋尾 隆, 村山 徹, 日吉 範人, 上田 渉

  石油学会要旨集 2018年 公益社団法人 石油学会
   

  水熱合成によりW-V複合酸化物触媒を合成した。各種キャラクタリゼーションにより本触媒のバルク・表面構造を決定した。本触媒はトルエンの安息香酸への選択酸化に高い収率（７０％）を示した。対照触媒との比較から活性種の局所構造を提案する。
• メタンの有効利用を目的とした機械学習による吸着エネルギー予測

  鳥屋尾隆, 鳥屋尾隆, 高草木達, 瀧川一学, 清水研一, 清水研一

  触媒討論会討論会A予稿集 2018年
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  清水研一, POLY Sharmin S., 前野禅, 鳥屋尾隆, SIDDIKI S. M. A. Hakim

  石油・石油化学討論会講演要旨 2018年
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  石油・石油化学討論会講演要旨 2018年
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  西鳥羽俊貴, 津野地直, 江原正博, 窪田好浩, 清水研一, 佐野庸治, 小倉賢, 横井俊之

  ゼオライト研究発表会講演予稿集 2018年
• Cu-ZSM-5を用いたNH₃-SCR反応の反応工学に基づく解析

  神田拓海, 中坂佑太, 清水研一, 今健一, 柴田元, 増田隆夫

  ゼオライト研究発表会講演予稿集 2018年
• NO-CO反応に高いN₂選択性を示すPd系合金触媒の開発

  全載完, 古川森也, 古川森也, 今健一, 清水研一, 清水研一

  触媒討論会討論会A予稿集 2018年
• Operando分光法によるCuゼオライト上でのNH₃-SCR機構解析

  天田雄大, 今健一, 鳥屋尾隆, 鳥屋尾隆, 植田格弥, 大山順也, 大山順也, 薩摩篤, 薩摩篤, 清水研一, 清水研一

  触媒討論会討論会A予稿集 2018年
• Cu-Ni合金触媒を用いた添加物フリーなアルケンのヒドロホウ素化

  古川森也, 家田繭子, 清水研一

  触媒討論会討論会A予稿集 2018年
• Cu-ZSM-5によるNH₃-SCRの拡散,反応速度解析

  神田拓海, 中坂佑太, 清水研一, 今健一, 柴田元, 増田隆夫

  触媒討論会討論会A予稿集 2018年
• ハイシリカゼオライト触媒を用いたエポキシド及びアルキンの高効率水和反応

  前野禅, 今健一, POLY Sharmin Sultana, TOUCHY Abeda Sultana, SIDDIKI S. M. A. Hakim, 鳥屋尾隆, 鳥屋尾隆, 清水研一, 清水研一

  触媒討論会討論会A予稿集 2018年
• Re/TiO₂を用いた二酸化炭素水素化反応によるメタノールの選択的合成

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  触媒討論会討論会A予稿集 2018年
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  触媒討論会討論会A予稿集 2018年
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  触媒討論会討論会A予稿集 2018年
• 機械学習を用いた金属表面における反応活性因子の予測  [通常講演]

  瀧川一学, 清水研一, 津田宏治, 高草木達

  表面科学学術講演会講演要旨集 2017年08月 公益社団法人 日本表面科学会
   

  金属のdバンド中心は、様々な触媒反応の活性序列を示す良い指標である。dバンド中心は第一原理計算によって求めるが、種々の金属やバイメタル系に対して網羅的に計算を行うのは、計算・時間コストが高くなる。そこで本研究では，金属の密度，イオン化エネルギー等の入手容易な物理量を記述子とし、種々の金属・合金のdバンド中心の機械学習による高速予測を検討し，その結果、妥当な精度で予測できることを実証した。
• 担持Pt触媒による2級アルコールとアミノアルコールからの2,5-二置換ピロールの合成

  清水研一, 鳥屋尾隆, 清水研一, 鳥屋尾隆, TOUCHY Abeda S., HAKIM SIDDIKI S. M. A.

  触媒討論会講演予稿集 2017年
• セリア触媒を用いた第3級アミドのアルコールによるエステル化反応

  鳥屋尾隆, 鳥屋尾隆, SIDDIKI S M A H, 森田能次, 蒲池高志, 蒲池高志, 吉澤一成, 吉澤一成, 清水研一, 清水研一

  触媒討論会講演予稿集 2017年
• 担持Pt触媒上での水素化脱酸素反応におけるLewis酸性担体の役割  [通常講演]

  今健一, 清水研一, 清水研一

  触媒討論会講演予稿集 2015年03月
• Lewis酸性酸化物担持Pt触媒による二酸化炭素・カルボン酸の還元的官能基変換  [通常講演]

  清水研一, 清水研一, SIDDIKI S, M. A. H, TOUCHY Abeda S, 今健一

  触媒討論会講演予稿集 2015年03月
• 担持Pt触媒上での二酸化炭素と水素によるアミンのメチル化  [通常講演]

  清水研一, 今健一

  石油・石油化学討論会講演要旨 2014年10月
• Pt/HZSM5触媒を用いたレブリン酸水素化によるペンタン酸・ペンタン酸エステルの合成  [通常講演]

  今健一, 清水研一

  石油・石油化学討論会講演要旨 2014年10月
• 水熱合成W‐V‐O複合酸化物触媒によるピコリンのアンモ酸化  [通常講演]

  後藤文倫, 村山徹, 清水研一, 上田渉

  石油・石油化学討論会講演要旨 2014年10月
• 担持Pt触媒による二酸化炭素と水素を用いたアミンのメチル化  [通常講演]

  今健一, 清水研一

  触媒討論会討論会A予稿集 2014年09月
• 水熱合成W‐V‐O複合酸化物触媒によるピコリンのアンモ酸化  [通常講演]

  後藤文倫, 村山徹, 清水研一, 上田渉

  触媒討論会討論会A予稿集 2014年09月
• 二酸化炭素・カルボン酸を還元的に化学品・燃料に変換する固体触媒  [通常講演]

  清水研一

  触媒討論会討論会A予稿集 2014年09月
• 種結晶添加による斜方晶MoOx酸化物の水熱合成  [通常講演]

  田代雅也, 石川理史, 坂口紀史, 村山徹, 清水研一, 上田渉

  触媒討論会討論会A予稿集 2014年09月
• Ni‐MoOx/C触媒を用いたレブリン酸水素化によるγ‐バレロラクトンの合成  [通常講演]

  清水研一, 菅野翔太, 今健一

  触媒討論会講演予稿集 2014年03月
• Pt/HZSM5触媒を用いたレブリン酸水素化によるペンタン酸合成  [通常講演]

  清水研一, 今健一

  触媒討論会講演予稿集 2014年03月
• 不定比ニッケル酸化物の高い酸素還元反応活性  [通常講演]

  大山順也, 渡部憲幸, 清水研一, 竹口竜弥, 上田渉, 薩摩篤

  電気化学秋季大会講演要旨集 2013年09月
• 金属ナノ粒子と酸化物担体の協働作用を利用した有機合成  [通常講演]

  清水研一

  触媒討論会討論会A予稿集 2013年09月
• 担持Ni触媒によるカルボン酸の還元反応  [通常講演]

  菅野翔太, 清水研一

  触媒討論会討論会A予稿集 2013年09月
• 表面を酸素修飾したPd/Cによるシランの酸化反応に関する理論的研究  [通常講演]

  蒲池高志, 清水研一, 久保隆寛, 薩摩篤, 吉澤一成

  触媒討論会討論会A予稿集 2013年09月
• 担持Pt触媒を用いたカルボン酸の水素化  [通常講演]

  清水研一, 今健一

  触媒討論会討論会A予稿集 2013年09月
• 鉄添加アルミナ担持Ptクラスター触媒上での低温CO酸化メカニズム  [通常講演]

  冨田衷子, 清水研一, 加藤和男, 秋田知樹, 多井豊

  ナノ学会大会講演予稿集 2013年06月
• Ni/CaSiO₃触媒によるアルコールとアンモニアからの選択的1級アミン合成  [通常講演]

  菅野翔太, 清水研一

  触媒討論会講演予稿集 2013年03月
• アルミナ担持白金触媒上でのアルコール脱水素反応機構  [通常講演]

  今健一, 清水研一

  触媒討論会講演予稿集 2013年03月
• アルミナ担持Ni触媒によるアルコール脱水素とアルコールとアンモニアからの1級アミン合成  [通常講演]

  清水研一, 小野寺渉, 今健一

  触媒討論会講演予稿集 2013年03月
• 珪酸カルシウム担持Ni触媒の表面状態の観測  [通常講演]

  田中英之, 酒多喜久, 今村速夫, 清水研一

  日本化学会講演予稿集 2013年03月
• クリーンディーゼル触媒開発のための放射光利用  [通常講演]

  薩摩篤, 清水研一

  日本放射光学会年会・放射光科学合同シンポジウム予稿集 2013年01月
• 酸素還元反応活性に対するカーボン担持Ag触媒のサイズと表面化学状態の効果  [通常講演]

  大山順也, 大方裕衣, 渡部憲幸, 片桐誠, 清水研一, 竹口竜弥, 薩摩篤

  触媒討論会討論会A予稿集 2012年09月
• アルカリ条件下でのニッケル酸化物触媒の酸素還元活性  [通常講演]

  渡部憲幸, 大山順也, 清水研一, 竹口竜弥, 薩摩篤

  触媒討論会討論会A予稿集 2012年09月
• 担持金属ナノ粒子触媒による脱水素・水素化活性とd‐band中心との相関  [通常講演]

  清水研一, 田村正純, 薩摩篤

  触媒討論会討論会A予稿集 2012年09月
• Ni/CeO₂触媒を用いたアルコールとアンモニアからの1級アミンの直接合成  [通常講演]

  菅野翔太, 清水研一

  触媒討論会討論会A予稿集 2012年09月
• FT‐IRによる金属酸化物の酸塩基性の包括的解析  [通常講演]

  田村正純, 清水研一, 薩摩篤

  触媒討論会討論会A予稿集 2012年09月
• 反応場・ルイス酸・ナノ粒子によるバイオマス転化反応の効率化  [通常講演]

  薩摩篤, 清水研一, 大山順也

  触媒討論会討論会A予稿集 2012年09月
• 担持Pt触媒を用いた酸化剤フリーアルコール脱水素  [通常講演]

  今健一, 清水研一

  触媒討論会討論会A予稿集 2012年09月
• 低温CO酸化活性を有する水賦活Pt‐Fe/Alumina触媒における調製条件の検討  [通常講演]

  冨田衷子, 清水研一, 多井豊

  触媒討論会討論会A予稿集 2012年09月
• 混成電位式アンモニアセンサ用検知電極の金属酸化物修飾効果  [通常講演]

  菅谷聡, 柿元志郎, 中埜吉博, 小島多喜男, 清水研一, 薩摩篤

  日本セラミックス協会秋季シンポジウム講演予稿集(CD-ROM) 2012年09月
• 貴金属代替技術の最新動向 自動車排ガス浄化用Ag触媒:高活性化とシンタリング抑制の方策  [通常講演]

  清水研一, 沢邊恭一, 薩摩篤

  触媒 2012年06月
• 担持Pd触媒上での低温CO酸化反応における活性制御因子  [通常講演]

  薩摩篤, 大崎薫, 大山順也, 清水研一

  石油学会年会講演要旨 2012年05月
• Hydration of nitriles to amides in water by SiO2-supported Ag catalysts promoted by adsorbed oxygen atoms  [通常講演]

  SHIMIZU Ken-ichi, IMAIIDA Naomichi, SAWABE Kyoichi, SATSUMA Atsushi

  Appl Catal A Gen 2012年04月
• 金属酸化物修飾Au電極を用いた混成電位式アンモニアセンサ  [通常講演]

  菅谷聡, 柿元志郎, 中埜吉博, 小島多喜男, 清水研一, 薩摩篤

  電気化学会大会講演要旨集 2012年03月
• ニトリルの水和反応におけるO/Ag,Ag₂O表面の酸素による促進効果に関する理論研究  [通常講演]

  松本望, 今飯田真道, 清水研一, 薩摩篤, 沢邊恭一

  触媒討論会討論会A予稿集 2012年03月
• 担時コバルト触媒による酸化剤非存在下でのアルコール脱水素  [通常講演]

  清水研一, 瀬戸真弓, 志村勝也

  触媒討論会討論会A予稿集 2012年03月
• In situ Raman分光法を用いたRh/CeO₂の酸化還元特性の評価  [通常講演]

  柳原将俊, 大山順也, 小田智徳, 清水研一, 薩摩篤

  触媒討論会討論会A予稿集 2012年03月
• 酸化セリウム触媒によるニトリルのone‐potエステル化反応  [通常講演]

  田村正純, 殿村拓也, 清水研一, 薩摩篤

  触媒討論会討論会A予稿集 2012年03月
• 担持Ni触媒の脱水素・水素化能を利用したOne‐pot C‐C,C‐N結合形成反応  [通常講演]

  志村勝也, 今飯田真道, 薩摩篤, 清水研一

  触媒 2012年03月
• 水賦活Pt/FeOx‐Al₂O₃触媒によるCO低温酸化の反応機構  [通常講演]

  冨田衷子, 清水研一, 加藤和男, 多井豊

  触媒討論会討論会A予稿集 2012年03月
• アニオン交換膜形燃料電池カソード用ニッケル酸化物触媒における粒子径効果  [通常講演]

  渡部憲幸, 大山順也, 清水研一, 竹口竜弥, 薩摩篤

  触媒討論会討論会A予稿集 2012年03月
• 担持Ni触媒によるアルコールのカップリング反応  [通常講演]

  志村勝也, 清水研一

  化学系学協会北海道支部冬季研究発表会講演要旨集 2012年01月
• 表面を酸素修飾したPd/Cによるニトリルおよびシランの選択水和反応  [通常講演]

  久保隆寛, 清水研一, 薩摩篤

  化学系学協会北海道支部冬季研究発表会講演要旨集 2012年01月
• 担持卑金属触媒を用いたグリーン有機合成反応  [通常講演]

  今飯田真道, 清水研一, 薩摩篤

  化学系学協会北海道支部冬季研究発表会講演要旨集 2012年01月
• CeO₂の酸・塩基特性を用いたone‐potアミド・エステル合成  [通常講演]

  殿村拓也, 田村正純, 清水研一, 薩摩篤

  化学系学協会北海道支部冬季研究発表会講演要旨集 2012年01月
• 自動車排ガス浄化用自己再生型Agナノクラスター触媒  [通常講演]

  清水研一

  表面科学学術講演会講演要旨集 2011年12月
• Agナノ粒子触媒をカソードに用いたアニオン交換膜形燃料電池  [通常講演]

  片桐誠, 清水研一, 竹口竜弥, 渡部憲幸, 薩摩篤

  触媒討論会討論会A予稿集 2011年09月
• Cu/Agバイメタル触媒を用いたアルコールによるアミンのN‐アルキル化  [通常講演]

  清水研一, 志村勝也, 西村雅翔, 薩摩篤

  触媒討論会討論会A予稿集 2011年09月
• 担持Ni触媒を用いたカルボニル化合物の水素移動型還元反応  [通常講演]

  志村勝也, 清水研一

  触媒討論会討論会A予稿集 2011年09月
• 酸化セリウムによる基質特異的ニトリル水和反応とその機構解明  [通常講演]

  田村正純, 田村正純, 若杉浩子, 殿村拓也, 吉川幸男, 清水研一, 沢邊恭一, 薩摩篤

  触媒討論会討論会A予稿集 2011年09月
• 表面を酸素で修飾したPd/C触媒によるニトリルの水和  [通常講演]

  久保隆寛, 清水研一, 薩摩篤

  触媒討論会討論会A予稿集 2011年09月
• 酸化セリウム触媒を用いたトランスアミド化  [通常講演]

  殿村拓也, 田村正純, 田村正純, 清水研一, 薩摩篤

  触媒討論会討論会A予稿集 2011年09月
• 担持Ni触媒を用いたアルコールによるアミンのN‐アルキル化  [通常講演]

  今飯田真道, 清水研一, 薩摩篤

  触媒討論会討論会A予稿集 2011年09月
• 自己分散性を利用したRu/CeO₂触媒上でのCO酸化反応  [通常講演]

  柳原将俊, 清水研一, 薩摩篤

  化学工学会秋季大会研究発表講演要旨集(CD-ROM) 2011年08月
• 鉄添加アルミナ担体上でのPtクラスターの高いCO酸化活性  [通常講演]

  冨田衷子, 清水研一, 多井豊

  ナノ学会大会講演予稿集 2011年06月
• 時間分解in‐situ UV‐VisによるRh/アルミナ触媒における還元過程の速度解析  [通常講演]

  林強, 清水研一, 薩摩篤

  石油学会年会講演要旨 2011年05月
• セリア触媒上でのニトリルからの直接エステル合成における反応機構  [通常講演]

  殿村拓也, 田村正純, 清水研一, 薩摩篤

  触媒討論会討論会A予稿集 2011年03月
• CeO₂(111)上でのシアノピリジンのアミド化反応機構の理論計算による解明  [通常講演]

  吉川幸男, 田村正純, 清水研一, 薩摩篤, 沢邊恭一

  触媒討論会討論会A予稿集 2011年03月
• 水で賦活処理したPt‐Fe/Al₂O₃触媒によるCO低温酸化  [通常講演]

  冨田衷子, 秋田知樹, 清水研一, 多井豊

  触媒討論会討論会A予稿集 2011年03月
• アルミナ上へのAgの自発的分散化現象を利用した自己再生型酸化触媒の開発  [通常講演]

  清水研一, 沢邊恭一, 薩摩篤

  触媒 2011年03月
• 酸化セリウムを触媒としたアミド合成  [通常講演]

  田村正純, 若杉浩子, 殿村拓也, 清水研一, 薩摩篤

  触媒 2011年03月
• 担持Pdクラスター触媒を用いたアミンの選択的クロスカップリング反応  [通常講演]

  大島啓一郎, 清水研一, 薩摩篤

  石油・石油化学討論会講演要旨 2010年11月
• セリア触媒を用いたニトリル化合物のアルキルアミド化  [通常講演]

  殿村拓也, 田村正純, 清水研一, 薩摩篤

  石油・石油化学討論会講演要旨 2010年11月
• 酸化セリウムを触媒としたニトリル化合物からのエステルone‐pot合成  [通常講演]

  田村正純, 殿村拓也, 清水研一, 薩摩篤

  石油・石油化学討論会講演要旨 2010年11月
• Cu‐Ag合金ナノ粒子を用いた水素添加反応における組成比の影響  [通常講演]

  西村雅翔, 清水研一, 薩摩篤

  石油・石油化学討論会講演要旨 2010年11月
• Agナノ粒子触媒上でのニトリルの水和反応における表面酸素原子の影響  [通常講演]

  今飯田真道, 清水研一, 薩摩篤

  触媒討論会討論会A予稿集 2010年09月
• 担持Pd触媒を用いたCO及び炭化水素燃焼反応におけるPdの酸化状態の影響  [通常講演]

  大崎薫, 清水研一, 薩摩篤

  触媒討論会討論会A予稿集 2010年09月
• Ag/Al₂O₃触媒を用いたアルコールとニトロベンゼンからのone potアミン合成  [通常講演]

  西村雅翔, 清水研一, 薩摩篤

  触媒討論会討論会A予稿集 2010年09月
• 金属酸化物上でのアルドール縮合反応における活性因子の計算化学的検討  [通常講演]

  志村直隆, 清水研一, 沢邊恭一, 薩摩篤

  触媒討論会討論会A予稿集 2010年09月
• アルミナ上に担持したサブナノ白金粒子によるCO低温酸化  [通常講演]

  冨田衷子, 白石愛, 蔭山博之, 清水研一, 薩摩篤, 多井豊

  触媒討論会討論会A予稿集 2010年09月
• 担持Ptクラスター触媒を用いたアミンの選択的クロスカップリング反応  [通常講演]

  大島啓一郎, 清水研一, 薩摩篤, 富田衷子, 多井豊

  触媒討論会討論会A予稿集 2010年09月
• 自己再生型Ag/SnO₂触媒によるカーボン燃焼  [通常講演]

  片桐誠, 川地浩史, 清水研一, 薩摩篤

  触媒討論会討論会A予稿集 2010年09月
• 担持Pd触媒を用いたシランの水和反応における活性種  [通常講演]

  久保隆寛, 清水研一, 薩摩篤

  触媒討論会討論会A予稿集 2010年09月
• 触媒燃焼用Rh/セリアにおける高温エージングの効果  [通常講演]

  小田智徳, 清水研一, 薩摩篤

  石油学会年会講演要旨 2010年05月
• アルミナ担持金触媒を用いたニトロスチレンの選択的水素化  [通常講演]

  清水研一, 宮本裕士, 薩摩篤, 多井豊

  石油学会年会講演要旨 2010年05月
• 液相還元法により作製した金コア‐白金シェルナノ粒子のPEFCカソード触媒特性  [通常講演]

  山口渡, 清水研一, 薩摩篤, 多井豊

  電気化学会大会講演要旨集 2010年03月
• Rh L₃‐edge XANESを用いた担持Rh触媒のキャラクタリゼーション  [通常講演]

  清水研一, 小田智徳, 薩摩篤

  触媒討論会討論会A予稿集 2010年03月
• 銀粉‐酸化スズ混合触媒によるカーボン燃焼  [通常講演]

  清水研一, 川地浩史, 薩摩篤

  触媒討論会討論会A予稿集 2010年03月
• 各種酸化物によるニトリルの水和反応  [通常講演]

  田村正純, 若杉浩子, 清水研一, 薩摩篤

  触媒討論会討論会A予稿集 2010年03月
• アルミナ担持金・銀触媒を用いた芳香族ニトロ化合物の選択的水素化  [通常講演]

  清水研一, 山本拓実, 宮本裕士, 多井豊, 薩摩篤

  触媒 2010年03月
• Pd担持タングステン酸触媒上での多環芳香族水素化反応における担体効果  [通常講演]

  林強, 清水研一, 薩摩篤

  石油・石油化学討論会講演要旨 2009年10月
• ヘテロポリ酸系触媒を用いたセルロース/セロビオースの加水分解―Lewis酸と共役塩基の効果―  [通常講演]

  古川容竹, 清水研一, 薩摩篤

  石油・石油化学討論会講演要旨 2009年10月
• 金クラスターと固体酸塩基の協奏効果によるオキシムの選択合成  [通常講演]

  山本拓実, 清水研一, 薩摩篤

  石油・石油化学討論会講演要旨 2009年10月
• C₃H₆酸化反応用Pd/CeO₂触媒における高熱負荷の影響  [通常講演]

  佐藤亮太, 清水研一, 薩摩篤

  触媒討論会討論会A予稿集 2009年09月
• Ag/Al₂O₃触媒を用いたアルコールによるアミンのN‐アルキル化における活性制御因子  [通常講演]

  西村雅翔, 清水研一, 薩摩篤

  触媒討論会討論会A予稿集 2009年09月
• ヘテロポリ酸触媒によるセルロース・セロビオースの糖化  [通常講演]

  清水研一, 古川容竹, 薩摩篤

  触媒討論会討論会A予稿集 2009年09月
• 銀クラスターとアルミナの酸塩基点の共同作用を利用した合成反応  [通常講演]

  清水研一

  触媒討論会討論会A予稿集 2009年09月
• 排ガスモニタリング用混成電位式アンモニアセンサの金属酸化物修飾効果  [通常講演]

  片桐誠, 清水研一, 柿元志郎, 菅谷聡, 松谷渉, 薩摩篤

  触媒討論会討論会A予稿集 2009年09月

作品等

• 低温燃焼用銀ナノクラスター触媒の開発と機構解明

  2009年 -2009年
• 修飾ポリ酸触媒による高効率セルロース糖化反応

  2008年 -2008年
• イオン交換ヘテロポリ酸による高効率固体ルイス酸触媒の開発

  2007年 -2007年
• 尿素脱硝用銀クラスター触媒の開発と作用機構解析

  2007年
• ディーゼル脱硝用金属酸化物触媒の分子設計

  2000年 -2002年
• 灯油の超深度脱硫技術の開発

  2001年 -2001年
• ディーゼル脱硝用金属酸化物系触媒の分子設計

  2000年 -2000年
• 金属酸化物系ディーゼル脱硝触媒の開発

  2000年 -2000年

その他活動・業績

• 機械学習により見出された逆水性ガスシフト反応に有効な多元素触媒の作用機構研究

  峯真也, 陳鐸天, 王剛, 鳥屋尾隆, 瀧川一学, 瀧川一学, 松下康一, 清水研一 触媒討論会討論会A予稿集(CD-ROM) 130th 2022年
• TiO₂表面上の分子吸着に関するフロンティア軌道理論

  蒲池高志, 蒲池高志, 濱本信次, 巽俊暢, 高尾基史, 鳥屋尾隆, 鳥屋尾隆, 日沼洋陽, 前野禅, 高草木達, 古川森也, 古川森也, 瀧川一学, 清水研一, 清水研一 日本化学会春季年会講演予稿集(Web) 102nd 2022年
• 機械学習を利用した逆水性ガスシフト反応に有効な多元素触媒の開発

  峯真也, 陳鐸天, 王剛, 鳥屋尾隆, 鳥屋尾隆, 前野禅, 瀧川一学, 瀧川一学, 松下康一, 真崎仁詩, 清水研一, 清水研一 触媒討論会講演予稿集(CD-ROM) 129th 2022年
• Understanding and controlling the formation of surface anion vacancies for catalytic applications

  Shinya Mine, Takashi Toyao, Yoyo Hinuma, Ken Ichi Shimizu Catalysis Science and Technology 12 (8) 2398 -2410 2022年 

  Defects are important as they often govern the chemical and physical properties of solid materials. Surface defect sites, such as anion vacancies, most commonly oxygen vacancies for oxides, are well-known reaction sites in heterogeneous catalysis. Although the importance of defects at catalyst surfaces is well recognized and commonly accepted by the catalysis community, details of their atomic and electronic structures are lacking, which is largely because identifying surface defects is challenging and mostly beyond the resolution of currently available experimental techniques. Moreover, the complexities of the geometrical and electronic structures of surfaces make computational investigations difficult. Presently, studying an individual material requires substantial amounts of experimental and calculation time/cost; hence, few comprehensive studies have been performed. In this Perspective, we summarize our recent systematic computational efforts using density functional theory to calculate surface anion vacancy formation energies (Evac) as important descriptors of catalytic performance. The systems explored include binary oxides, complex oxides, carbides, nitrides, sulfides, hydrides, and oxides with supported metals. Exotic surfaces with high-index orientations were also considered. In addition, we studied relationships between physicochemical properties and surface anion Evac values in order to rationalize the properties of compounds/surfaces and the support metals and to provide a predictive tool. The definitive goal of our work was to gain fundamental knowledge of the factors determining surface defect formation and ultimately catalytic activity/selectivity so that ideal catalytic materials/surfaces can be designed and manipulated in a highly precise manner.
• インジウム交換ゼオライト触媒による選択的エタン脱水素反応

  前野禅, 安村駿作, 鳥屋尾隆, 鳥屋尾隆, 清水研一, 清水研一 触媒討論会討論会A予稿集(CD-ROM) 128th 2021年
• ZrO₂担持Rh触媒を用いたO₂共存下での触媒的N₂O分解

  竹歳昂一郎, 鳥屋尾隆, 鳥屋尾隆, 前野禅, 大堀鉄平, 石川直也, 清水研一, 清水研一 触媒討論会討論会A予稿集(CD-ROM) 128th 2021年
• Electron scavenger効果による活性化が見込める触媒担体のスクリーニング

  日沼洋陽, 日沼洋陽, 濱本信次, 前野禅, 鳥屋尾隆, 蒲池高志, 清水研一 触媒討論会討論会A予稿集(CD-ROM) 128th 2021年
• CuCHA上のFast SCR反応機構

  清水研一, LIU Chong, 鳥屋尾隆, 前野禅 触媒討論会討論会A予稿集(CD-ROM) 128th 2021年
• In situ分光・電子顕微鏡を用いた銀アルミナ触媒上のアンカーサイトの研究

  窪田博愛, 峯真也, 鳥屋尾隆, 鳥屋尾隆, 前野禅, 清水研一, 清水研一 触媒討論会討論会A予稿集(CD-ROM) 128th 2021年
• CO₂吸蔵・水素化による選択的CO生成反応に有効な固定化Pt触媒の開発

  宮崎眞太, 鳥屋尾隆, 鳥屋尾隆, 前野禅, 清水研一, 清水研一 触媒討論会討論会A予稿集(CD-ROM) 128th 2021年
• 機械学習を用いたCO₂/H₂混合ガスによる芳香族化合物のメチル化反応用触媒の最適化

  陳家偉, 鎌倉春花, 鳥谷尾隆, 前野禅, 松下康一, 清水研一 触媒討論会討論会A予稿集(CD-ROM) 128th 2021年
• Rich/Leanサイクル条件下におけるRh-MORの低温deNOx活性と反応機構解析

  加藤大雪, 錢宇澄, 安村駿作, 鳥屋尾隆, 鳥屋尾隆, 前野禅, 清水研一, 清水研一 触媒討論会討論会A予稿集(CD-ROM) 128th 2021年
• TiO₂表面上の分子吸着に関するフロンティア軌道理論

  濱本信次, 巽俊暢, 高尾基史, 鳥屋尾隆, 鳥屋尾隆, 日沼洋陽, 前野禅, 高草木達, 古川森也, 古川森也, 瀧川一学, 清水研一, 清水研一, 蒲池高志, 蒲池高志 分子科学討論会講演プログラム&要旨(Web) 15th 2021年
• 外挿的探索を可能にする機械学習モデルを用いた新規触媒探索

  向山拓実, 峯真也, 鳥屋尾隆, 鳥屋尾隆, 前野禅, 高草木達, 瀧川一学, 瀧川一学, 清水研一, 清水研一 触媒討論会討論会A予稿集(CD-ROM) 128th 2021年
• 外挿的探索が可能な機械学習手法を用いた水性ガスシフト反応触媒の文献データ解析と新規触媒予測

  峯真也, 鳥屋尾隆, 鳥屋尾隆, 前野禅, 瀧川一学, 瀧川一学, 清水研一, 清水研一 触媒討論会討論会A予稿集(CD-ROM) 128th 2021年
• 計算材料設計最前線2021 理論計算とセラミックス触媒担体設計-多様な表面の特性計算-

  日沼洋陽, 清水研一, 蒲池高志 セラミックス 56 (10) 2021年
• Cu-AFXゼオライト上でのアンモニア脱硝メカニズム

  窪田博愛, 鳥屋尾隆, 清水研一 ゼオライト 38 (1) 2021年
• 水蒸気存在下での低温脱硝を目指したタングステン添加酸化バナジウム触媒

  猪股雄介, 清永英嗣, 盛田啓一郎, 吉田和広, 窪田博愛, 鳥屋尾隆, 清水研一, 春田正毅, 村山徹, 村山徹 石油・石油化学討論会講演要旨 50th (Web) 2020年
• 先端材料開発や化学プロセスに応用されるマテリアルズ・インフォマティクス 機械学習・計算化学を併用した固体触媒研究

  鳥屋尾隆, 清水研一, 瀧川一学, 瀧川一学 分離技術 50 (1) 2020年
• CO₂とH₂からの低温メタノール合成

  鳥屋尾隆, 清水研一 水素エネルギーシステム 45 (1) 2020年
• 触媒インフォマティクスの動向

  鳥屋尾隆, 清水研一, 瀧川一学 科学と工業 94 (7) 2020年
• 機械学習を併用した触媒・反応探索:最近の動向

  鳥屋尾隆, 清水研一 CICSJ Bulletin (Web) 38 (1) 2020年
• 固体触媒による含窒素有機化合物変換の最前線 固体表面の酸化還元・酸塩基機能を利用した含窒素有機化合物の合成

  清水研一, 鳥屋尾隆, SIDDIKI S.M.A.Hakim 触媒 61 (5) 2019年
• トルエンの安息香酸への選択酸化に高活性なW-V複合酸化物触媒の活性種構造

  清水研一, 後藤文倫, 鳥屋尾隆, 村山徹, 日吉範人, 上田渉 石油学会年会講演要旨 61st 2018年
• 金属/酸化物界面の協働触媒作用に基づくサステナブルな化学品合成

  清水研一 触媒 60 (4) 2018年
• 機械学習を用いた金属表面における反応活性因子の予測

  瀧川一学, 清水研一, 津田宏治, 高草木達 表面科学学術講演会講演要旨集 37th 2017年
• 組成情報と要素特徴量の統合に基づく化学反応量の予測

  鈴木慶介, 瀧川一学, 瀧川一学, 清水研一, 高草木達 人工知能学会全国大会論文集(CD-ROM) 31st 2017年
• 自動車排ガス浄化用Ag触媒 : 高活性化とシンタリング抑制の方策

  清水 研一, 沢邊 恭一, 薩摩 篤 觸媒 = Catalyst 54 (4) 228 -234 2012年06月10日
• 担持Ni触媒の脱水素・水素化能を利用した One-pot C-C, C-N 結合形成反応

  志村 勝也, 今飯田 真道, 薩摩 篤, 清水 研一 觸媒 = Catalyst 54 (2) 132 -134 2012年03月10日
• 酸化セリウムを触媒としたアミド合成

  田村 正純, 若杉 浩子, 殿村 拓也, 清水 研一, 薩摩 篤 觸媒 = Catalyst 53 (2) 123 -125 2011年03月10日
• アルミナ上へのAgの自発的分散化現象を利用した自己再生型酸化触媒の開発

  清水 研一, 沢邊 恭一, 薩摩 篤 觸媒 = Catalyst 53 (2) 107 -109 2011年03月10日
• アルミナ担持金・銀触媒を用いた芳香族ニトロ化合物の選択的水素化

  清水 研一, 山本 拓実, 宮本 裕士, 多井 豊, 薩摩 篤 觸媒 = Catalyst 52 (2) 107 -109 2010年03月10日
• NOx還元過程におけるNSR触媒の活性制御因子

  齊藤 良典, 清水 研一, 信川 健, 薩摩 篤 觸媒 = Catalyst 51 (2) 73 -75 2009年03月10日
• In-situ 分光法による自動車触媒の反応機構解析

  薩摩 篤, 清水 研一 表面科学 : hyomen kagaku = Journal of the Surface Science Society of Japan 30 (2) 98 -103 2009年02月10日
• NOx吸蔵還元触媒の反応機構と性能制御因子

  清水 研一, 齊藤 良典, 薩摩 篤 觸媒 = Catalyst 51 (1) 57 -62 2009年01月15日
• ゼオライト細孔内に固定化した二核銅錯体の構造と酸化触媒作用

  清水 研一 ゼオライト 26 (3) 108 -114 2009年
• 希薄燃焼エンジン排ガスのためのNOx還元触媒 (特集 環境触媒--期待される21世紀の兵たち)

  薩摩 篤, 清水 研一 マテリアルインテグレ-ション 22 (1) 13 -18 2009年01月
• 銀アルミナ触媒による酸化剤を用いないアルコール脱水素反応

  清水 研一, 杉野 賢治, 薩摩 篤 觸媒 = Catalyst 50 (6) 523 -525 2008年09月10日
• Hydrogen assisted urea-SCR and NH3-SCR with silver-alumina as highly active and SO2-tolerant de-NOx catalysis

  Ken-ichi Shimizu, Atsushi Satsuma APPLIED CATALYSIS B-ENVIRONMENTAL 77 (1-2) 202 -205 2007年11月 [査読有り][通常論文]
   

  Addition of 0.5% H-2 in the selective catalytic reduction of NO by urea (urea-SCR) caused a drastic improvement of NO reduction activity of Ag/Al2O3. Among various silver-based catalysts Ag/Al2O3 showed highest activity for H-2 assisted urea-SCR, and high NO conversion (above 84%) and no formation of N2O were achieved over wide temperature range (200-500 degrees C) at GHSV of 75,000 h(-1). After H-2 assisted urea-SCR at 250 degrees C with 10% H2O and 50 ppm SO2 under GHSV of 380,000 h(-1) for 24 h, NO conversion over Ag/Al2O3 decreased from 48 to 30%, though original activity was recovered when the deactivated catalyst was heated at 500 degrees C in the urea-SCR condition for 1 h. The catalyst also showed high SO2-tolerance in H-2 assisted NH3-SCR at 200 degrees C. (C) 2007 Elsevier B.V. All rights reserved.
• 水素添加による銀アルミナ触媒の尿素・アンモニア脱硝活性の向上と作用機構

  清水 研一, 薩摩 篤 触媒 = Catalysts & Catalysis 49 (2) 114 -116 2007年03月10日
• 酸素分子の還元的活性化を利用したNO選択還元用銀アルミナ触媒の飛躍的活性向上

  清水 研一, 都築 正雄, 薩摩 篤 触媒 = Catalysts & Catalysis 48 (6) 377 -379 2006年09月10日
• Pt担持タングステン酸ジルコニアを感応層とする水素センサ

  鎮西 勇夫, 清水 研一, 薩摩 篤 Proceedings of the Chemical Sensor Symposium 42 160 -162 2006年09月
• WO3/ZrO2を感応層とするアンモニアセンサの特性と検知機構 (第96回触媒討論会B講演予稿)

  清水 研一, 遠藤 忠嗣, 柏木 幸一 触媒 47 (6) 427 -429 2005年09月
• BEAゼオライト内に固定化したペルオキソ二核銅錯体によるベンゼンから二価フェノールへの選択光酸化反応

  清水 研一, 丸山 怜, 赤羽 広也, 児玉 竜也, 北山 淑江 触媒 = Catalysts & Catalysis 47 (2) 75 -77 2005年03月01日
• FSM-16固定化Pd触媒によるクロスカップリング反応

  清水 研一, 小泉 壮一, 児玉 竜也, 北山 淑江 触媒 = Catalysts & Catalysis 46 (6) 533 -535 2004年09月10日
• FSM-16固定化二級アミン触媒上でのアルデヒドの直接的求核付加反応

  清水 研一, 林 永大, 濱谷 潤, 児玉 竜也, 萩原 久大, 北山 淑江 触媒 = Catalysts & Catalysis 45 (6) 525 -527 2003年09月10日
• シリカ固定化不斉触媒による炭素-炭素結合生成反応

  清水 研一 触媒 = Catalysts & Catalysis 45 (1) 51 -51 2003年01月15日
• Ag/Al_2O_3 上での NO 選択還元反応における H_2添加効果

  里川 重夫, 清水 研一, 柴田 順二, 薩摩 篤, 服部 忠 触媒 42 (6) 407 -409 2000年09月10日
• Deconvolution Analysis of Cu L-edge XANES for Quantification of Copper(2)Coordinations in Copper-aluminate Catalysts (Proceedings of the Second International Conference on SRMS(Synchrotron Radiation in Materials Science)(2))

  Shimizu Ken-ichi, Maeshima Hajime, Yoshida Hisao Japanese Journal of Applied Physics Pt. 1 Regular Papers, Short Notes & Review Papers 38 (1) 44 -46 1999年06月
• 遷移金属-アルミネート触媒上でのNO選択還元反応機構

  清水 研一, 川端 久也, 前嶋 肇, 吉田 寿雄, 薩摩 篤, 服部 忠 触媒 41 (2) 93 -95 1999年03月10日
• プロパン脱水素反応に対する酸化ガリウム触媒構造の影響

  西 宏二, 高松 幹生, 清水 研一, 駒井 慎一, 吉田 寿雄, 薩摩 篤, 服部 忠 触媒 39 (2) 78 -81 1997年03月10日
• Na-H-モルデナイト上でのNO-C_3H_6-O_2反応機構

  薩摩 篤, 圓城寺 隆之, 清水 研一, 吉田 寿雄, 服部 忠 触媒 38 (6) 442 -445 1996年09月10日

特許

• 液体炭化水素燃料の脱硫方法

  特開2003-049172
• エステル化触媒、エステル製造方法、アシル化触媒及びアシル化物製造方法

  特開2006-110539
• 水素ガスセンサ

  特開2007-218814
• NOx浄化システム及びNOx浄化方法

  特開2007-332885
• ビスフェノール類の製造方法

  特開2008-031139
• ビスフェノール類の製造方法

  特開2008-120791
• 排気ガス浄化用触媒及びその製造方法

  特開2001-300320

受賞

• 2024年03月 日本化学会第41回学術賞
  
• 2023年02月 北海道大学教育研究総長表彰
  
• 2015年03月 北海道大学 研究総長賞 奨励賞
   

  受賞者: 清水 研一
• 2014年03月 北海道大学 研究総長賞
   

  受賞者: 清水 研一
• 2010年05月 第45回東海化学工業会賞(学術賞)
   

  受賞者: 清水 研一
• 2010年03月 触媒学会 奨励賞
   

  受賞者: 清水 研一
• 2007年05月 石油学会 奨励賞
   

  受賞者: 清水 研一
• 2006年 Elsevier Applied Catalysis B: Environmental, Most Cited Author 2001-2005
   

  受賞者: 清水 研一
• 2000年07月 12th International Congress on Catalysis 触媒会議賞（第12回国際触媒会議）
   

  受賞者: 清水 研一

共同研究・競争的資金等の研究課題

• ヒドロキシ基含有鋳型によるゼオライトナノシートの新規合成と触媒開発

  日本学術振興会：科学研究費助成事業

  研究期間 : 2022年04月 -2026年03月 

  代表者 : 津野地 直, 清水 研一, 池田 拓史, 日吉 範人
• オペランド分光による活性種の動的挙動解析を基盤とする非定常・連続触媒反応の開拓

  日本学術振興会：科学研究費助成事業 基盤研究(A)

  研究期間 : 2021年04月 -2026年03月 

  代表者 : 清水 研一

   

  本研究では、非定常条件（Modulation Excitation、過渡応答法）でのOperando分光（赤外、紫外可視、X線吸収）により過渡的に観測される活性種を特定し、その活性種の濃度・反応性を最大化する条件を意図的に設定することで、従来の定常反応研究では未探索の触媒現象を発見することを目的とする。具体的には、３種のターゲット系（①室温脱硝、②メタンのドライリフォーミング、③劣化触媒の自己再生）を非定常操作の繰り返しにより連続的に達成する固体触媒系の開発を目的とする。また、触媒毒や微粒子の凝集等、定常反応では不可避の問題点を過渡的な条件変動により回避し、表面の潜在力を最大化する。基礎研究（表面科学）と応用研究（触媒プロセス）の両分野の手法を融合し、反応研究における未踏領域を開拓する。 ２０２１年度は、赤外分光（IR）、紫外可視分光（UV-vis）、X線吸収分光（XAFS）の試料セル（反応温度に加熱）に各種反応ガスを流し、出口のガスを質量分析器(MS)または赤外分光（ガスセル）にて連続分析する装置を作成した。各装置のガス供給部に高速での周期的流通ガス供給・切り替え装置を設置し、Operando ME分光測定が可能な装置が完成した。本装置を用いて、雰囲気制御による凝集金属の可逆的自己再生現象を発見した。担体に高分散担持された触媒は高温での連続使用の最中に徐々にシンタリングするため、触媒性能は徐々に低下する。ディーゼル脱硝用に車載されているAg/Al2O3触媒の活性成分であるAgの融点(962℃)は白金(1769℃)に比べて低いため、従来型のPt触媒に比べてAg微粒子が凝集しやすい。本研究では、高温水素処理で加速劣化させたAg/Al2O3上の巨大Ag粒子（粒径50 nm）を典型的なディーゼル排ガス（500ppmNO+10%O2）に曝すと、もとの高活性ナノ構造（原子状に分散したAg）に戻ることを見出した。
• 外挿的探索が可能な機械学習手法を用いた多元素触媒の開発

  日本学術振興会：科学研究費助成事業

  研究期間 : 2022年04月 -2024年03月 

  代表者 : 清水 研一, LI LINGCONG
• バルク・ナノ金属の高分散化現象の機構解明と単原子触媒の設計開発への展開

  日本学術振興会：科学研究費助成事業 特別研究員奨励費

  研究期間 : 2021年11月 -2024年03月 

  代表者 : 清水 研一

   

  γ-Al2O3担持Ag(Ag/Al2O3)触媒はディーゼル脱硝に用いられる工業触媒である．原子レベルで分散したAg+種が本系の必須要素であるが，触媒の劣化・再生やAg+種のアンカーサイトの構造に関しては検討の余地がある．本研究ではH2中でのAg+種の還元凝集と酸化雰囲気(NO＋O2)におけるAg+種の再生(再分散)を各種分光法により追跡した.Ag3/Al2O3(Ag = 3 wt.%)はベーマイトに硝酸銀水溶液を含浸後, 600 ℃で焼成して調製した.各測定の前に再度600 ℃でO2 (10%)処理を行った.反応は常圧流通反応装置にて行った(0.5% H2; 0.1% NO; 0.1%NH3; 10% O2)．HAADF-STEM測定より，焼成後(fresh)のAg3/Al2O3の主なAg種は単原子状Ag+であった．H2中，800 ℃で処理した試料(sintered)では，原子状Ag+種は消失し粒子径10-52 nmの凝集したAg NPsが観察された．XRDではAg(111)に帰属できる強い回折線が観測され，XAS でも金属Ag NPが主なAg種であることがわかった．H2処理後の試料をNO+O2中, 400℃で処理した試料(re-oxidized)では，単原子状Ag+の再生，Ag NPの回折線強度の減少，金属AgのEXAFSピークの消失とAg-O結合の再生が確認された。SCR反応における活性は還元処理により減少するが，再酸化後にfreshと同様の活性を回復した．以上の結果はNO+O2中でAg NPsが原子状のAg+種に再分散(活性種が再生)することで触媒活性が回復することを示す．
• 二酸化炭素水素化による低温メタノール合成に有効な高機能触媒系の開発

  日本学術振興会：科学研究費助成事業 特別研究員奨励費

  研究期間 : 2020年11月 -2023年03月 

  代表者 : 清水 研一, WANG GANG

   

  理論と実験を組み合わせた手法を用いて、温和な条件でのCO2水素化反応によるメタノール合成に有効な触媒開発を目指している。CO2から温和な条件でメタノールを製造する触媒プロセスは持続可能社会実現のためのコア技術であるが、反応の難度が高く、現在の触媒技術では十分な生成物収率が得られない。革新的な触媒設計が必要である。我々がこれまでに培ってきた理論計算に関する知見と、in situ/operando分光を組み合わせることでCO2有効利用触媒技術の開発・触媒設計指針の確立を行う本研究は非常に意義深いと考えている。 研究開始初期は、触媒スクリーニングを行った。具体的には、これまでの研究で用いてきた、すでに調製・構造解析済みの50種類ほどの担持触媒を用いて低温でのメタノール合成反応を行った。さらに、In situ/Operando分光や速度論解析を用いて、有望な触媒の構造・電子状態を決定し、活性・選択性との相関から性能制御因子を決定した。その際、情報科学を利用した"触媒インフォマティクス"に関する知見も積極的に利用した。 今後、実験・理論・データ科学を組み合わせた新しい研究アプローチを用いて、CO2水素化反応によるメタノール合成の学理を築いていく。固体触媒の設計理論は体系化されていない部分が多く、触媒探索の方法論は「絨毯爆撃的なスクリーニング」から脱却できていない。苦労の末開発した新触媒も1つの成功例で終わってしまう。開発した新規触媒を単なる1成功例に終わらせることなく、その高性能要因を抽出し一般化することで、さらなる高活性触媒開発の礎とする。
• その場観察分光法を用いた二酸化炭素水素化触媒の活性点構造の研究

  日本学術振興会：科学研究費助成事業 特別研究員奨励費

  研究期間 : 2019年11月 -2021年03月 

  代表者 : 清水 研一, MALTA GRAZIA

   

  逆水性ガスシフト(RWGS)反応は, 工業的な合成ガス製造法である．本反応に有効な触媒開発における課題は, 低温域におけるCO生成速度の向上と副生成物としてのCH4の生成抑制である．我々の研究グループでは，TiO2担持MoOx担体にPtを担持した触媒(Pt/MoOx/TiO2)が様々な水素化反応に有効であることを報告してきた．本研究ではこのPt/MoOx/TiO2触媒がRWGS反応にも有効であることを見出した． 担体であるMoO3(10)/TiO2 (Mo = 10 wt%)は，(NH4)6Mo7O24・4H2O 及びTiO2を前駆体として含浸法により調製した．Ptの担持は，Pt(NH3)2(NO3)2硝酸水溶液を用いてPt担持量が3 wt%となるように含浸法で行った．石英反応管に触媒50 mgを充填し，前処理をH2雰囲気下300 °Cで0.5 h行った．反応ガス組成は (H2/CO2/He/N2 = 40/10/40/5 mL/min)とし，反応温度250 °Cで活性測定を行った．生成物はTCD-GCを用いて分析した． MoO3(10)/TiO2とPt(3)/MoOx(10)/TiO2のHAADF-STEM観察から，MoOx種は粒子を形成せず, TiO2上に高分散に分布していることが明らかになった．Ptは，MoO3種に被覆された担体上に平均粒子径2.6 nmのナノ粒子として担持されていた．RWGS反応の活性試験を行った結果，Pt/MoOx(10)/TiO2触媒が最も活性が高いことが分かった．In situ Mo K殻 XANES測定によりMoOx種の酸化還元を研究中である. 予備実験より、Pt(3)/MoOx(10)/TiO2触媒にCO2を導入すると，XANESは高エネルギー側へシフトした．これは, MoOx種がCO2により酸化されることを示している.
• 実験と理論の協働によるメタン多量化反応の機構解明と触媒設計

  日本学術振興会：科学研究費助成事業 特別研究員奨励費

  研究期間 : 2019年04月 -2021年03月 

  代表者 : 清水 研一, LIU CHONG

   

  Non-oxidative dehydrogenation of C2H6 is an attractive chemical process to obtain C2H4 as an essential raw material for the chemical industry accompanied with H2 production. Our group found that the In-exchanged CHA zeolite (In-CHA) catalyzed the dehydrogenation of C2H6 in high selective manner without co-feeding gas. In-CHA maintained its activity and selectivity for at least 90 h. The active In species and the reaction mechanism were also investigated based on spectroscopic and theoretical studies. DFT calculations were performed by the Vienna ab-initio simulation package (VASP) with the periodic boundary condition.The FT-IR spectrum after C2H6 treatment exhibited the band with maxima at 1720 cm-1 derived from of In－H vibrations. The frequency calculation of several In-hydride models revealed that In－H vibrations of [InH2]+ ions are in good agreement with the results of FT-IR measurements. The TS calculation of C2H6 dehydrogenation via concerted mechanism on [InH2]+ ions shows that the activation barrier (Ea) for C－H cleavage of C2H6 is estimated to be 237.5 kJ/mol. This value is similar to Ea based on kinetic studies (244 kJ/mol) and is much lower than that in the TS calculation of dehydrogenation on In+ cations (430.8 kJ/mol). From the result of FT-IR measurement and TS calculations, [InH2]+ ions are likely to be catalytically active sites rather than In+ cations for the C2H6 dehydrogenation using In-CHA.
• 二酸化炭素・バイオマスの還元的化学資源化に資する金属/酸化物界面反応場設計

  日本学術振興会：科学研究費助成事業 基盤研究(A)

  研究期間 : 2017年04月 -2021年03月 

  代表者 : 清水 研一, 古川 森也, Siddiki Hakim, 鳥屋尾 隆

   

  天然物から直接入手できる炭素資源および，CO2から製造可能な炭素源を入手容易な軽分子と反応させて，化学品を選択的に合成する下記反応(1)～(8)の構築を目的として研究を継続した。(1) カルボン酸水素化によるアルコール合成。(2) カルボン酸（油脂）水素化によるアルカン合成。(3) メタノールをメチル化剤に用いたサステナブルなC-C結合形成。(4) レブリン酸とニトリルからのラクタム合成。(5) 油脂、NH3からのアミド合成。(6) 油脂、NH3からのニトリル合成。(7) 油脂、NH3、水素からのアミン合成。(8) CO2水素化によるメタノール合成。2017年度には，(2),(4),(3)に有効な触媒を発見し論文報告した。2018年度は，反応(1)，(3),(5)，(6)，(7)，(8)に有効な触媒に関する成果を論文発表した。2019年度は，反応(8)に有効な触媒を発見するとともに、反応(1),(7),(8)に関して反応機構と構造活性相関の研究を行い、その成果を論文にて報告した。具体的には， CO2水素化によるメタノール合成に有効な２つの触媒（Pt-MoOx/TiO2とRe/TiO2）を発見した。いずれの触媒系も１５０℃の低温で選択的にCO2をメタノールに変換する点が新規である。なかでもPt-MoOx/TiO2は最も活性が高く、１５０℃での平衡転化率に近いメタノール収率（７３％）を示した。水素還元により低原子価状態となったMo酸化物上の酸素欠陥がCO2の活性化に重要な役割を担うことが示唆された。Re/TiO2の水素加圧下でのカルボン酸の水素化においては、金属状態のReナノ粒子と４価のRe酸化物の共存状態が重要であることと、TiO2担体はReの粒子径を小さくすることとReを上記の酸化状態に保つために重要な役割を担うことを明らかにした。ゼオライト触媒のトリグリセリド変換に対して、触媒の疎水性と強酸量の両方が重要な活性支配因子であることを明確化した。
• 規整ナノ反応場の構築と新しい触媒機能の創出

  日本学術振興会：科学研究費助成事業 新学術領域研究(研究領域提案型)

  研究期間 : 2013年06月 -2018年03月 

  代表者 : 高草木 達, 原 賢二, 清水 研一, 松本 祐司, 瀧川 一学

   

  本研究では、表面金属ナノクラスター触媒（酸化物担持金属触媒）と固定化金属錯体触媒を用いた環境浄化及びグリーン有機合成反応をターゲットとし、単結晶モデル表面を始めとした規整ナノ反応場の原子レベル構造評価と実触媒の開発を並行して行った。担持金属触媒では、特に金属/酸化物界面に形成される特異なナノ構造による分子活性化に着目し、固定化金属錯体触媒では錯体の空間的配列や配向などの局所構造が触媒活性に与える影響を検討した。また、情報学的手法を用いた新規触媒物質の高速かつ高精度探索法の開拓を行った。
• サステナブル炭素資源からの化学品合成に有効な卑金属ナノクラスター触媒の開発

  日本学術振興会：科学研究費助成事業 基盤研究(B)

  研究期間 : 2014年04月 -2017年03月 

  代表者 : 清水 研一

   

  サステナブルな炭素源(CO2,カルボン酸類)を一段階で還元的に化学品へ変換する固体触媒法を探索した。カルボン酸をエステル，アルコール，アルカンに変換する3種の触媒系、レブリン酸をピロリドン類，γバレロラクトン，ペンタン酸に変換する3種の触媒系に加え、CO2+H2下でのアミンのメチル化、アミド水素化、スルホキシド・スルホンの水素化脱酸素に有効な触媒系も見出した．各触媒は再利用可能な不均一系触媒として作用し、幅広い基質に対して高い収率で目的物を与えた。反応機構・触媒構造に関する検討により、Lewis酸性担体によるC=O結合の活性化と隣接金属ナノ粒子上での水素解離を基盤とする触媒設計指針を提案した。
• ユニットネットワーク固体の構築工学展開による新機能触媒物質群形成

  日本学術振興会：科学研究費助成事業 基盤研究(A)

  研究期間 : 2011年04月 -2014年03月 

  代表者 : 上田 渉, 竹口 竜弥, 清水 研一, 村山 徹, 定金 正洋, 神谷 裕一

   

  ユニットが平面性および球状のポリ酸を合成系中で発生させ、水熱条件下でそれぞれ2次元平面ネットワーク構造、３次元立体ネットワーク構造を構築した。前者は６族、５族、４族のほとんどの元素の組み合わせが可能となり、ナノレベルで5員環状ポリ酸ユニットのネットワーク化を達成し、合成を一般化した。後者の３次元構造形成では、ε型ケギンユニットと金属酸素八面体リンカーが三次元的にネットワーク化した新しいゼオライト様の結晶物質の合成に成功し、構造の確定、対象元素の拡張、ミクロ細孔特性の解析を進めた。二酸化炭素やエタンに対する特異的な親和性を示した。得られた物質の非対称性ミクロ細孔場は新しい触媒機能を示した。
• 自己分散型クラスター・ナノ粒子による高耐久低温燃焼触媒の設計

  日本学術振興会：科学研究費助成事業 基盤研究(B)

  研究期間 : 2011年04月 -2014年03月 

  代表者 : 薩摩 篤, 清水 研一, 大山 順也, 沢邊 恭一

   

  本研究の目的は金属ナノ粒子・ナノクラスターの自己組織化を制御し、長寿命・低温活性触媒設計のための戦略を提案することである。成果として、(1) CeO2担体上のPd, Ag, Ruが加熱条件でナノサイズの粒子に再分散する挙動とその機構を明らかにし、(2)動作温度域を下げるためには金属の還元促進と酸素吸蔵放出能が鍵であり、(3)この知見から既存のPd/Al2O3触媒に比べてCO酸化反応温度域が約100℃低温化したPd/TiO2/CeO2を開発した。
• グリーン有機合成・自動車排ガス浄化用新規Ag触媒の設計

  日本学術振興会：科学研究費助成事業 若手研究(A)

  研究期間 : 2010年 -2012年 

  代表者 : 清水 研一

   

  環境調和型有機合成反応に対して白金族錯体を上回る性能を示す不均一系Ag触媒を開発した。また,白金属系固体触媒よりも高い活性とシンタリング耐性を示す自動車排ガス処理用Ag触媒を開発した。機構論・構造論的検討により,金属ナノクラスターと酸化物界面の協働効果を鍵とする設計指針を構築した。
• ナノクラスター化による銀触媒の新規機能発現

  日本学術振興会：科学研究費助成事業 基盤研究(B)

  研究期間 : 2008年 -2010年 

  代表者 : 薩摩 篤, 清水 研一, 沢邊 恭一

   

  本研究では銀のナノクラスター、ナノ粒子の新たな触媒機能を明らかにし、次にかかげる新規触媒反応系を開拓した。(1)ディーゼルパーティキュレートの低温燃焼、(2)アルコールの選択的脱水素反応、(3)原子効率の高いワンポットC-C,C-N結合形成反応、(4)ニトロ化合物の選択水素化。
• 尿素脱硝用銀クラスター触媒の開発と作用機構解析

  日本学術振興会：科学研究費助成事業 若手研究(B)

  研究期間 : 2007年 -2009年 

  代表者 : 清水 研一

   

  尿素脱硝法はディーゼル自動車排ガスからの窒素酸化物(NOx)除去に有効であるが、更なる触媒活性向上が求められている。本研究では尿素によるNOx還元に対する銀アルミナ触媒の活性が水素添加により飛躍的に向上することを見出した.速度論解析,各種分光法により,本系における反応機構,活性種の構造を検討し,水素添加により生成する銀クラスターを活性種とする促進機構を提案した.
• 熱-光ハイブリット活性セラミックによる低温水分解反応の開発

  日本学術振興会：科学研究費助成事業 萌芽研究

  研究期間 : 2006年 -2007年 

  代表者 : 児玉 竜也, 清水 研一

   

  本研究では,高温(1400℃)で進行する反応性セラミックによる2段階水熱分解サイクル反応を,半導体の光化学的効果を他金属ドープで反応性セラミックに添加するという手法で低温化する試みを行った。これを研究代表者が見出した水熱分解性セラミック「Fe^<2+>-Fe^<3+>含有型立方晶ジルコニア」で検討した。すなわち,反応性セラミックを反応デバイス化し,これに擬似太陽集光を直接照射して行う活性試験と,反応性セラミックの固体化学的・光触媒化学的な構造解析によるアプローチを併用して,低温水分解性セラミックの開発を行った。19年度は下記の研究成果を得た。 (1)1400℃における水素発生量増大化の検討:デバイスへの反応性セラミック担持量を増大することを目的に,スピンコート法へ担持法を変更した。担持プロセスを大幅に簡便化でき,鉄酸化物を約10wt%担持量するために数十回を要していた繰り返し担持を数回で到達できるようになり,担持量を増大させることが容易になった。1100-1400℃の水分解試験の結果,反応性セラミック粉末試料の熱活性のみの場合と比較して1.2倍に水分解活性が向上することが見出された。粉末試料の方が反応デバイスと比較して反応表面積が大きく,高活性が得られるはずであるが,逆の結果が得られたことは,期待通りに光触媒効果が関与して活性を向上させていることを示唆している。 (2)低温化の検討:担持量を増大させたデバイスでは水素発生量は増大したが,焼結が起きやすくなり反応温度は1200-1500℃とむしろ増大した。一方,鉄酸化物の粉末試料ではあるが,予めNiとMnをドープすると1400℃の反応活性が増大することが見出され,この手法で1400℃以下の反応活性も向上できると考えられる。
• 銀ナノクラスターの触媒作用機構解明とディーゼル脱硝への展開

  日本学術振興会：科学研究費助成事業 基盤研究(B)

  研究期間 : 2005年 -2007年 

  代表者 : 薩摩 篤, 清水 研一, 沢辺 恭一

   

  [1.Agクラスターの反応性と機構解明]水素還元によってAgをクラスター化すると酸素との接触によりスーパーオキサイドを形成することをESRにより見いだした。Agクラスターの役割の本質が酸素の活性化にあることを示した。またAgクラスターのみならず表面にスピルオーバーした水素が活性促進に関与していることを見いだした。 [2.量子化学計算による検証]本研究費で購入したワークステーションを用いてゼオライト担体の場合をモデルとした量子化学計算によりAgクラスター形成の機構を検証した。Agの4核クラスター(Ag_4^<2+>)がゼオライト細孔内で最も安定であり、これは実験結果と一致した。水素化したAgクラスター(HH-Ag_4^<2+>)に酸素を接触させると過酸化水素状の吸着種の形成が確かめられた。この化学種は炭化水素部分酸化及びNOのNO_2への酸化に有効であり、実験事実が合理的であることを証明した。 [3.Agクラスター触媒の耐SOx性の検討]還元剤の種類、濃度、温度、水素添加の条件を最適化することで、Agクラスター触媒はSOx共存下でも触媒劣化を抑えることができることを明らかにした。さらに水素や炭化水素還元剤がAg表面の吸着SOxを気相、あるいは担体上に移動させることが高い耐SOx性の要因であることを明らかにした。
• 多価カチオン導入ヘテロポリ酸による新規固体酸触媒の開発

  日本学術振興会：科学研究費助成事業 萌芽研究

  研究期間 : 2005年 -2007年 

  代表者 : 薩摩 篤, 清水 研一

   

  酸触媒反応は化学工業に不可欠な反応であるが、逼常は再使用不可能な均一系触媒(AlCl_3,硫酸など)が用いられるため、廃棄物削減の観点から有効な固体酸触媒の開発が望まれている。これまで固体触媒による液相有機合成は、ゼオライト、メソポーラスシリカ、粘土等のシリケートによる検討が中心であり、新たな可能性が求められている。一昨年度、昨年度において多価カチオン交換ヘテロポリ酸触媒がFriedel-Craftsアシル化およびアルキル化に極めて高い活性を示すことを見いだした。本年度はこの触媒の(1)ビスフェノールAの合成、(2)フルクトース脱水反応への展開を試みた。ビスフェノールA合成には部分的なCsイオン交換と助触媒成分であるアミノチオールによる無機有機ハイブリッド修飾が有効であることを見いだした。これにはCsによる酸強度の調整とチオールによる基質の活性化促進が協奏して有効に作用していることを見いだした。最終的には94%と現在工業的に使用されるイオン交換樹脂系触媒に匹敵する無機固体酸触媒を設計することに成功した。またフルクトース脱水反応においてはFeイオン修飾したヘテロポリ酸触媒を用いた。この反応ではバイオマス由理原料から化成品原料となりうる5-ヒドロキシメチル-2-フルアルデヒド(HMF)が得られる。既報におけるHMFの最高収率は87%であるが、反応を排気条件下で行うことにより平行論的に有利な反応場となり97%の高収率が得られることを見いだした。
• 担持銀触媒上でのHC-SCRにおける表面ダイナミクス

  日本学術振興会：科学研究費助成事業 特定領域研究

  研究期間 : 2005年 -2006年 

  代表者 : 薩摩 篤, 沢辺 恭一, 清水 研一

   

  ディーゼルエンジンから発生する窒素酸化物(NOx)の除去法開発の取り組みが世界的に行われている。炭化水素による触媒選択還元法は有望な方式であり、担持Ag触媒は最有力候補の一つである。我々はAg触媒の特徴的な挙動として、表面Agが反応場に応じて可逆的に凝集・分散し、その際に生じるAgクラスターが極めて高い触媒活性を示すことを明らかにしている。本研究では表面Agクラスターの表面ダイナミクスと触媒反応活性の関係を検討する。本年度は班内での共同研究を含めて次の成果を得ることができた。 [1.In-situ EXAFSによるダイナミクス解析] これまでAgクラスターはin-situ UV-Visのみで観察していたが、今回鳥取大学奥村先生との共同研究によりQXAFS(SPring-8)によるin-situダイナミクス解析を試みた。酸素含有条件を基本とし、水素の添加によるAg種の構造変化を観察したところ、可逆的にAg-O結合とAg-Ag結合の配位数が変化した。すなわちAg^+イオンと平均原子数4個のAgクラスターが可逆的に形成していることをQXAFSによって確かめることができた。 [2.Agゼオライト上での反応中間体] In-situ FT/IRによりAgゼオライト上での反応機構の検討を行った。基本的にAg/Al_2O_3と同様にアセテートとナイトレートを経由してNOの窒素までの還元が進むが、新たな反応中間体としてCH_3NO_2を観察することが出来、後段のNCO種,NH3種を含む反応経路を明らかにすることができた。
• 高温太陽熱水分解のための反応性セラミックデバイスの開発

  日本学術振興会：科学研究費助成事業 基盤研究(B)

  研究期間 : 2005年 -2006年 

  代表者 : 児玉 竜也, 郷右近 展之, 清水 研一

   

  サンベルトで得られる高温太陽熱を利用し、水の熱分解で水素を製造する二段階水分解サイクルに必要とされる反応性セラミックデバイスの開発を行い、下記の研究成果を得た。 1.高反応性セラミック微粉体の開発 反応性セラミックとして研究代表者が開発したフェライト/ジルコニア担持体について他金属ドープ効果を比較し、高活性のNi_<1.0>Fe_<2.0>O_4/ZrO_4を見出した。一方、研究代表者は、担体を単斜晶ジルコニアから、イットリウム含有量が8mol%以上の立方晶安定化ジルコニア(YSZ)に替えると、熱還元反応においてFe^<2+>含有立方晶ジルコニアが生成し、低温水分解反応ではこれが水蒸気と反応して水素を生成しフェライトではなくFe^<3+>含有立方晶ジルコニアを生成するという新しいサイクル反応機構を見出した。 2.反応デバイスの合成と反応試験 Ni_<1.0>Fe_<2.0>O_4/ZrOとFe_3O_4/YSZの2つの微粉末反応体をそれぞれジルコニア発泡体に担持したデバイスを作製し、反応性を検討した結果、熱還元温度1400℃、水分解温度1100℃の2段階サイクル反応で13-30サイクル以上の水素発生が観測された。しかし、次第にデバイスの亀裂が起こった。そこで熱耐久性の高いSiC発泡体をマトリックスとすることとした。 3.SiC発泡体のジルコニア被覆と太陽光照射耐久試験による性能評価 熱力学計算からSiC発泡体をFe_3O_4に対して不活性のジルコニアで被覆することが必要であることが見出されたため、スピンコート法によりこれを検討し、良好なジルコニア被覆をすることができた。一方、SiC発泡体マトリックスについては、太陽炉による太陽光照射下試験で良好な熱耐久性を有することが確認された。
• 構造規則性無機有機複合触媒による環境調和型炭素-炭素結合形成反応

  日本学術振興会：科学研究費助成事業 若手研究(B)

  研究期間 : 2004年 -2006年 

  代表者 : 清水 研一

   

  ファインケミカル製品、中間体化学製品のような付加価値の高い物質の製造プロセスにおける多量の廃棄物の生成がグリーンケミストリーの観点から問題となっている。これは、これらの製造過程の多くが化学量論量の反応促進剤を用いた多段階の合成経路を経ることに起因する。触媒的にファインケミカルズを合成する方法も開発されてきたが、高価な金属錯体触媒の再利用が困難であることから、経済性、環境調和性に問題が残る。本研究は、有機分子を構造規則性無機担体に複合化した触媒による環境調和型触媒プロセスの構築を目的として研究を行ってきた。 平成17年度は、スルホン酸、メルカプト基等の有機分子を構造規則性無機担体に複合化した各種触媒の触媒性能を検討し、メソポーラスシリカと有機分子を複合化した材料が環境調和型の有機合成反応に有効な新規触媒系であることを示した。 平成18年度は、メソポーラスシリカ以外の機能性無機化合物と有機分子の複合化を試みたところ、層間水和能を示す新規層状タンタル酸塩の層間に各種アミンをインターカレーションさせることによる新規無機有機複合物質の合成に成功した。本物質は、タンタル酸化物ナノレイヤーの表面上に固体酸性を有し、挿入されたアミンには塩基点が存在することから、酸-塩基共同作用による新規触媒作用が期待できる。 以上の研究成果は、構造規則性無機有機複合触媒が環境調和型の有機合成反応に有効な新規触媒系であることを示している。
• 高/中温での太陽集熱による水素製造触媒デバイスの開発

  日本学術振興会：科学研究費助成事業 基盤研究(B)

  研究期間 : 2003年 -2004年 

  代表者 : 児玉 竜也, 清水 研一, 安藤 秀征, 佐藤 信博, 水野 修

   

  中・高温の太陽集熱を水素に転換する下記の2つの反応プロセスについて新規触媒デバイスの開発を行った。 1.高温(1000〜1500℃)用の反応性セラミックによる水の熱分解サイクル M_xO_y=M_xO_+δ/2O_2(高温酸素放出反応) M_xO_+δH_20=M_xO_y+δH_2(低温水分解反応) 高活性微粉体で発泡構造体に担持可能な反応性セラミックの開発を行い、さらに、微粉体をセラミック発泡構造体に担持し触媒デバイス化を行った。 1)高活性反応セラミックとしてフェライト/単斜晶ジルコニア担持体を見出しており、Fe_3O_4⇔FeOの相転移が担体上で起こり水分解が進行する。活性を向上させるドープ種を検討し、Niドープで高い反応効率(70%)が達成できた。 (2)フェライト/立方結晶ジルコニア担持体では、FeO固溶型ジルコニアが生成し、これが水分解に寄与するという新しい反応機構が発見された。この機構により鉄酸化物の融解・焼結による失活が回避され、サイクル反応性が向上することが見出された。 (3)反応性セラミックをSiC、及びZrO_2発泡構造体に20wt%以上担持した触媒デバイスを作製することができた。今後は本研究の成果を踏まえ、デバイスの反応試験を行う。 2.中温(500〜1000℃)用の天然ガス(メタン)の吸熱改質反応による水素製造 CH_4+2H_2O=3H_2+CO_2(吸熱メタン改質触媒反応) Ru/Al_2O_3担持Ni-Cr-Al合金発泡体触媒デバイスを高活性化する合成条件を見出した。さらに14cm径に大型化し、大型太陽炉で集光照射し、デバイスの熱的な特性評価を行った。従来のセラミック発泡体によるものと比較し、より高い熱伝導性を持つことからデバイス中心のオーバーヒートが回避され、全体に渡ってより均一な温度分布が達成されることが見出された。これは反応・エネルギー効率向上に大きく寄与する。
• 層状化合物を前駆体とする複合酸化物触媒合成法の開発

  日本学術振興会：科学研究費助成事業 萌芽研究

  研究期間 : 2003年 -2004年 

  代表者 : 薩摩 篤, 吉田 寿雄, 清水 研一, 服部 忠

   

  リン酸バナジウム((VO)_2P_2O_7)触媒はブタンの選択酸化による無水マレイン酸(MA)の製造に用いられるが,更なる生産性向上のために高ブタン分圧条件下での反応が検討されている.昨年度は新規助触媒添加法として,VP層状化合物であるvanadyl benzylphosphate前駆体の層間修飾による助触媒添加法を提案し,本法が高ブタン分圧条件への触媒の最適化に有効であることを示した。今年度は前駆体であるvanadyl benzylphosphateの精密な構造制御を目的として、調製条件を検討した。調製時における水の添加が層状化合物の層間隔と層間アルコール量を制御することを見いだしたので以下に報告する。 調製時の含水率を変えたところ、水添加量を上げていくにつれXRDの(001)回折線は低角側にシフトし,層間隔が広がっていた。一方,層方向に平行な(130)の回折位置は水添加量に依存せず,VP無機層の規則性には変化がなかった。層間は水添加量の増加に伴い1.37nm,1.90nm,2.25nmと増加した.化学組成およびIRより水添加により層間アルコールの含有量が低下していることが示された。また、SEMより板状結晶が剥離している状態が観察された。以上の結果から、VBP調製を無水条件で行った場合、層間のbenzyl alcoholのほとんどがリン酸エステルとしてVP無機層と結合し,層間はベンゼン環が密な状態充填される。これに対して水を添加した試料ではリン酸の結合が一部水酸基としてterminateされるため,層間のアルコールが減少し,結合力が弱くなった結果として,層間距離の増加と層剥離が起こったと考えられた。
• 光-熱ハイブリット活性型水分解性セラミックの開発

  日本学術振興会：科学研究費助成事業 萌芽研究

  研究期間 : 2003年 -2004年 

  代表者 : 児玉 竜也, 清水 研一

   

  本研究は従来の反応性セラミックによる1500℃付近における2段階水分解熱化学サイクル, M_xO_y=M_xO_+δ/2O_2 (高温酸素放出反応) M_xO_+δH_2O=M_xO_y+δH_2 (低温水分解反応) の反応系に、紫外-可視光応答性のある光半導体を導入して反応温度を低温化させる新しい「光-熱ハイブリット活性型反応性セラミック」を開発することを目的とする。本年度は下記の成果を得た。 1.反応試験用試料として反応性セラミックをディスク状のセラミック発泡体に担持した反応デバイスの作製を行った。光半導体で高温安定なSiCとZrO_2の発泡体を作製し、これにNiFe_2O_4/ZrO_2微粉体の反応性セラミックを担持した。石英窓付き反応器に設置し、模擬太陽集光を直接照射して1400℃に加熱し、光-熱ハイブリットによる活性化を試みた。この反応デバイスによる反応器は大型化も可能な設計であり、従来にない独特な方式と評価できる。 2.反応デバイスの構造変化を追跡し、ZrO_2発泡体のデバイスでは1400℃の活性化によりNiFe_2O_4を活性相のNi_<1/3>Fe_<2/3>Oへ還元できることを確認した。1000℃で水分解反応を行うと、水素を発生してNi_<1/3>Fe_<2/3>OがNiFe_2O_4へ再酸化され、サイクル反応が可能であることが見出された。 3.熱でのみ活性化を行った場合の反応効率を上回る結果は見られなかったが、これは、模擬太陽光照射下ではデバイスの温度分布が大きいため熱活性を十分に引き出せず、また光照射面積が十分でないことから光活性も十分に発現されてないことが要因と推察した。 4.今後は、本研究の成果を踏まえ、光照射が反応性セラミック粒子全体にいき渡る粉体流動層系で、光-熱ハイブリット活性化を検討することとし、試験用の石英窓を備えた流動層反応器を作製した。
• 反応場制御によるNOx選択還元触媒の高活性化

  日本学術振興会：科学研究費助成事業

  研究期間 : 2002年 -2004年 

  代表者 : 薩摩 篤, 吉田 寿雄, 清水 研一, 服部 忠

   

  環境保全の観点から、燃焼排ガスからの窒素酸化物(NOx)排出抑制技術の開発が急務となっている。本研究では触媒の反応場による制御に着目し、反応雰囲気制御を含めた触媒設計法を構築することを目的とした。昨年度までの成果として、Ag/alumina触媒上でのプロパンによるNO還元反応において、微量の共存水素がNO還元活性を著しく向上させ、その原因がAg ionic clusterの形成であることを見いだした。本年度は活性種であるAg ionic clusterを制御するための知見を得るため、Agゼオライトをモデル触媒としてAg ionic cluster形成に対する担体の効果を明らかにした。MFI, BEAでは反応ガスに少量の水素を添加することによりNO還元活性が飛躍的に向上したが、1%を頂点に徐々に活性は低下した。MORでは少量の水素添加では活性に変化は見られなかったが、高濃度の水素を添加すると活性は向上した。Yについては水素濃度に関わらずほとんど変化は見られなかった。同じ水素分圧で反応した後の触媒のUV-visスペクトルから、MOR上にはAg ion, MFI, BEA上にはAg ionic cluster,そしてY型ゼオライト上にはAg metallic clusterが形成していることが分かった。すなわち、Agの分散度はMOR>MFI>BEA>Yの序列であった。この序列は酸強度のそれと一致し、Ag種の分散-凝集度は担体ゼオライトの酸強度に依存していることが示された。Ag-MFIにおいて水素共存下での高いNO還元活性が得られるのは適度な担体酸強度により凝集度が中程度のAg ionic clusterが形成される為であり、活性の制御は気相の水素分圧と同時に担体酸強度が重要であることが明らかとなった。
• ディーゼル脱硝用金属酸化物触媒の分子設計

  文部科学省：科学研究費補助金(奨励研究(A), 若手研究(B))

  研究期間 : 2001年 -2002年 

  代表者 : 清水 研一

   

  炭化水素によるNO選択還元反応が、酸素過剰雰囲気下での新しいNOx除去プロセスを目指した触媒反応として注目されている。これまで主に検討されてきた金属イオン交換ゼオライトは、本反応に高い活性を示すものの、実用化においては耐久性の問題が指摘されている。一方、金属酸化物触媒も本反応に活性を示すことが早くから知られているが、活性の点ではゼオライト系触媒には及ばないとされてきた。本研究では、昨年度に引き続き、高い耐久性を持つ酸化物触媒のディーゼル排ガス模擬条件での脱硝特性を検討するとともに、活性支配因子に関する表面化学的検討を行った。種々の触媒上でのNO選択還元特性における炭化水素の種類を検討し、その結果を金属交換ゼオライト触媒での結果と比較考察した。その結果、どちらの系も炭素鎖長の長い炭化水素を還元剤として用いた方が高い脱硝性能を示すものの、活性向上率はアルミネート系の触媒においてより著しいことが示された。一方、X線吸収スペクトル,UV-VISにより、触媒の局所構造解析を行い、高沸点炭化水素、SO_x存在下でも高い性能を示す触媒の構造的特性を明らかにした。X線吸収スペクトルを中心とした触媒の局所構造の解析を行い、触媒活性成分の担体上への高分散化、配位数の制御がディーゼル脱硝特性に影響することを明らかにした。本結果により触媒の構造最適化への的確な指針を得た。また、反応前後の触媒構造解析により、触媒の耐久性向上の方策を提案した。上記検討から得られる指針をもとに、ディーゼル脱硝に高性能を示す新規触媒システムを提案した。
• 脱硝触媒 グリーン触媒

  研究期間 : 1996年
• De-NOx catalysis Green catalysis

  研究期間 : 1996年

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