Article
Chemistry, Physical
Han Zhao, Hongcheng Li, Yuanlong Tan, Tianzhi Liu, Huifeng Zhang, Qingde Zhang, Hangrong Chen, Yunkun Zhao, Xiao Yan Liu
Summary: The mixing-calcination-aging strategy can enhance the catalytic performance and oxygen storage capacity of three-way catalysts, but it leads to a transient drop in conversion rate, which is caused by the reduction of PdO.
APPLIED CATALYSIS A-GENERAL
(2022)
Article
Engineering, Environmental
Han Zhao, Hongcheng Li, Huifeng Zhang, Depeng Zhao, Zengzan Zhu, Yunkun Zhao
Summary: Careful NH3 or urea treatment can improve the catalytic activity of Pd catalysts, while the newly designed CO-TPR method is closely related to catalyst reducibility and total oxygen storage capacity. When using the most effective Urea-PP technology during monolith converter preparation, an outer layer is needed to protect the inner layer.
CHEMICAL ENGINEERING JOURNAL
(2021)
Article
Chemistry, Applied
Yuan Jing, Gang Wang, Zen Maeno, Shuhei Nagaoka, Ken-ichi Shimizu, Takashi Toyao
Summary: This study investigates the promotional effect of La in the Pd/La/Al2O3 catalyst for catalytic NO reduction. Spectroscopic methods were used to further explore the mechanism. The results indicate that the promotional effect of La is related to the efficient generation and reactivity of nitrite species. Additionally, the high-loading Pd/La/Al2O3 catalyst is superior in the TWC process and exhibits good stability even after aging at 800°C.
Article
Chemistry, Physical
Wallace T. Figueiredo, Ravi Prakash, Clovis G. Vieira, Dirlleia S. Lima, Vagner E. Carvalho, Edmar A. Soares, Silvio Buchner, Hannes Raschke, Oscar W. Perez-Lopez, Daniel L. Baptista, Roland Hergenroder, Maximiliano Segala, Fabiano Bernardi
Summary: This study utilized NAP-XPS, UPS, and DFT calculations to investigate the electronic factor of the SMSI effect in Pd/TiO2 nanoparticles, revealing charge transfer from Pd nanoparticles to TiO2 support through Pd-O-Ti entities at the Pd-TiO2 interface during reduction treatment at 300 degrees C.
APPLIED SURFACE SCIENCE
(2022)
Article
Chemistry, Multidisciplinary
Valery Muravev, Jerome F. M. Simons, Alexander Parastaev, Marcel A. Verheijen, Job J. C. Struijs, Nikolay Kosinov, Emiel J. M. Hensen
Summary: This study unveiled the rich structural dynamics of a conventional catalyst during CO oxidation, confirming the presence of different active intermediates at different temperatures. The results highlight the importance of establishing structure-activity relationships for technical catalysts.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2022)
Article
Chemistry, Physical
Verena Pramhaas, Matteo Roiaz, Noemi Bosio, Manuel Corva, Christoph Rameshan, Erik Vesselli, Henrik Gronbeck, Guenther Rupprechter
Summary: Pt/ZrO2 model catalysts were prepared using ALD and studied through a combination of experimental techniques and theoretical calculations to understand CO adsorption and reaction processes. The researchers found that the onset of CO reaction depends on a delicate balance between CO disproportionation and oxidation, with initial CO oxidation being influenced by the removal of carbon deposits under current conditions.
Article
Chemistry, Multidisciplinary
[Anonymous]
Summary: The dynamic behavior of ceria-supported Pd single atoms, clusters, and nanoparticles during CO oxidation was investigated using operando spectroscopy. The catalytic role of different Pd species was elucidated through a combination of in situ spectroscopy with transient and steady-state kinetic analysis, revealing that highly dispersed Pd-oxo species and interfacial Pd sites catalyze low-temperature CO oxidation, while metallic Pd contributes to the activity at elevated temperature.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2022)
Article
Materials Science, Multidisciplinary
Yulin Wei, Guopu Shi, Jun Ji, Fuxin Liang, Deli Ma, Xinyu Li, Zhe Pang, Honglei Wang, Zhi Wang, Qinggang Li
Summary: Inexpensive and effective palladium catalysts using alpha-alumina are crucial for pollution remediation and drug synthesis. The addition of a thin coating of gamma-alumina containing Ce and P elements on the a-alumina foam ceramics significantly improved the catalyst's properties. The interaction between Ce and P elements enhanced the oxygen storage capacity and weakened the binding strength, resulting in a mixed state of Pd-0, PdO, and Pd2+ in the catalyst.
JOURNAL OF MATERIALS SCIENCE
(2023)
Article
Chemistry, Applied
Marie D. Stromsheim, Ingeborg-Helene Svenum, Mehdi Mahmoodinia, Virginia Boix, Jan Knudsen, Hilde J. Venvik
Summary: The study observed that the CO2 formation profile during CO oxidation on a Pd75%Ag25%(100) single crystal is influenced by the history of the sample and previous heating conditions. The NAP-XPS data confirmed a dynamic segregation behavior of Pd in the surface region during temperature cycling. However, the relative area assessment of the Pd 3d(5/2) core level was not able to capture all the surface dynamics due to probing depth limitations.
Article
Chemistry, Multidisciplinary
Andrey V. Bukhtiyarov, Igor P. Prosvirin, Maxim A. Panafidin, Alexey Yu. Fedorov, Alexander Yu. Klyushin, Axel Knop-Gericke, Yan V. Zubavichus, Valery I. Bukhtiyarov
Summary: This study investigated the catalytic activity of HOPG-supported bimetallic Pd-Au catalysts towards CO oxidation by varying the Pd/Au atomic ratio. The results showed distinct differences in ignition temperatures and activity between catalysts with different initial Pd/Au atomic ratios.
Article
Chemistry, Multidisciplinary
Linjun Qi, Ming Dong, Jinlong Qian, Shuling Yu, Xiaofeng Tong
Summary: In this study, the combination of an H-bonding donor [PyH][BE4] and AgNO3 additive under a toluene/H2O biphasic system was found to enable the reductive elimination of alkyl-Pd-II-O, forming alkyl nitrate. The Pd-0-catalyzed asymmetric carbonitration of (Z)-1-iodo-1,6-dienes using (R)-BINAP as the chiral ligand provided alkyl nitrates with up to 96% ee. Mechanistic studies revealed that the reaction involves oxidative addition, anion ligand exchange, alkene insertion, and S(N)2-type reductive elimination of alkyl-Pd-II-ONO2.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Physical
Jingjun Huang, Matthew Isaac, Ryan Watt, Joseph Becica, Emma Dennis, Makhsud Saidaminov, William A. Sabbers, David C. Leitch
Summary: The study introduces an easily prepared and stable mononuclear Pd(0) source that is effective for catalytic reactions and has good solubility properties.
Article
Chemistry, Physical
Donato Decarolis, Adam H. Clark, Tommaso Pellegrinelli, Maarten Nachtegaal, Evan W. Lynch, C. Richard A. Catlow, Emma K. Gibson, Alexandre Goguet, Peter P. Wells
Summary: This study utilized operando spectroscopy to spatially profile a Pd/Al2O3 catalyst during NH3 oxidation, revealing insights into structure-activity relationships in catalysis. The results showed a direct correlation between the presence of PdNx and selectivity toward N-2, and proposed two simultaneous reaction pathways at high temperatures. These findings highlight the structural and catalytic diversity during catalysis, emphasizing the importance of understanding for improving emission control technologies like selective catalytic oxidation of NH3.
Article
Chemistry, Physical
Shreya Nandi, Jiang Xiang Wu, Pardis Simon, Nicolas Nuns, Martine Trentesaux, Asma Tougerti, Emiliano Fonda, Jean-Sebastien Girardon, Jean-Francois Paul, Anne-Sophie Mamede, Elise Berrier
Summary: This study investigates the redox behavior of Cu- or Mn-doped LaFeO3-based perovskite powders under TWC conditions, revealing fundamentally different structures. Cu-dLFO demonstrates the expulsion of Cu2+ cations as segregated CuO phase, while Mn-dLFO stabilizes most Mn3+ cations within the perovskite solid solution, with additional iron exsolution. Both catalysts show redox activity during CO oxidation/NO reduction, with varying operating modes based on their different structures.
APPLIED CATALYSIS B-ENVIRONMENTAL
(2021)
Article
Chemistry, Inorganic & Nuclear
Han Zhao, Longchun Bian, Junchen Du, Yunkun Zhao
Summary: This study found that moderate doping of Pd into CeO2 and less intimate CeO2-Al2O3 interaction can enhance the catalytic activity of three-way catalysts. Catalysts prepared by co-precipitation method have higher Pd dispersion and specific surface area, resulting in better catalytic performance.
DALTON TRANSACTIONS
(2022)
Article
Chemistry, Applied
Yuan Jing, Gang Wang, Zen Maeno, Shuhei Nagaoka, Ken-ichi Shimizu, Takashi Toyao
Summary: This study investigates the promotional effect of La in the Pd/La/Al2O3 catalyst for catalytic NO reduction. Spectroscopic methods were used to further explore the mechanism. The results indicate that the promotional effect of La is related to the efficient generation and reactivity of nitrite species. Additionally, the high-loading Pd/La/Al2O3 catalyst is superior in the TWC process and exhibits good stability even after aging at 800°C.
Article
Energy & Fuels
Shinta Miyazaki, Zirui Li, Lingcong Li, Takashi Toyao, Yuta Nakasaka, Yasushi Nakajima, Ken-ichi Shimizu, Zen Maeno
Summary: In this study, Ni-modified tungstate zirconia (Ni/WO3/ZrO2) was developed as an effective material for chemical looping dry reforming of methane (CL-DRM) under isothermal conditions. The performance of Ni/WO3/ZrO2 was strongly influenced by the loading amount of WO3, with the optimal amount being 10.0 wt%. Increasing the loading amount to 30.0 wt% resulted in the formation of crystalline WO3 species and diminished the CL-DRM performance. Comprehensive characterization studies revealed that surface dispersed tungstate species were reduced by CH4 and reoxidized by CO2, leading to efficient CL-DRM.
Article
Chemistry, Inorganic & Nuclear
Kosuke Shimoda, Satoshi Ishikawa, Mai Miyasawa, Ken-ichi Shimizu, Wataru Ueda
Summary: In this study, a new class of high-dimensionally structured molybdenum oxide (HDS-MoO(x)) was reported, which was constructed by the random assembly of {Mo6O21}(6-) pentagonal units (PUs). HDS-MoO(x) could generate a substantial amount of lattice oxygen defects without causing crystal structure changes. It showed higher oxidation ability compared to typical molybdenum oxide.
INORGANIC CHEMISTRY
(2023)
Article
Chemistry, Physical
Meilin Tao, Satoshi Ishikawa, Takuji Ikeda, Shunsaku Yasumura, Kosuke Shimoda, Ryota Osuga, Yuan Jing, Takashi Toyao, Ken-ichi Shimizu, Hiromi Matsuhashi, Wataru Ueda
Summary: In this study, the crystal structure and acid properties of Zr3SO9 were investigated. It was found that Zr3SO9 exhibited excellent catalytic activity for acid reactions, surpassing typical acid catalysts. The introduction of H2O transformed the acid sites of Zr3SO9, resulting in a shift from Lewis to Bronsted acid sites.
Article
Chemistry, Physical
Ningqiang Zhang, Shinta Miyazaki, Yucheng Qian, Yuan Jing, Takashi Toyao, Ken-ichi Shimizu
Summary: Kinetic analyses of Ce4+ <-> Ce3+ redox and CO2/H-2 formation for the unsteady-state water-gas shift (WGS) reaction are carried out on Cu/CeO2 catalysts under periodic CO <-> H2O feeds at 350 degrees C. The results provide quantitative evidence of the redox-based mechanism of the reaction and suggest that Ce3+- reoxidation by H2O has a lower barrier than Ce4+-O reduction. The number of interfacial sites between CeO2 and Cu species affects the turnover frequencies for the redox reaction and CO2/H-2 formation. An associative redox mechanism based on the redox reaction between Cu2+-OH and Ce4+-OH/Ce4+ and Cu+--Ce3+ is proposed as the main catalytic cycle of the reaction.
Article
Engineering, Environmental
Ningqiang Zhang, Jiahuan Tong, Shinta Miyazaki, Shirun Zhao, Hiroe Kubota, Yuan Jing, Shinya Mine, Takashi Toyao, Ken-ichi Shimizu
Summary: This study investigates the active sites and reaction mechanism for the selective catalytic reduction of NO by NH3 over phosphate-loaded ceria catalysts. The results reveal the presence of H3PO4 and H2P2O6 species on the catalysts, which interact with Ce4+(OH-) species and undergo reduction/oxidation half-cycles to produce N2, H2O, and Ce3+ species.
ENVIRONMENTAL SCIENCE & TECHNOLOGY
(2023)
Article
Multidisciplinary Sciences
Shunsaku Yasumura, Kenichiro Saita, Takumi Miyakage, Ken Nagai, Kenichi Kon, Takashi Toyao, Zen Maeno, Tetsuya Taketsugu, Ken-ichi Shimizu
Summary: Automated reaction route mapping is used to design catalysts for low-temperature CH4 combustion with ozone. A suitable proton-type zeolite catalyst with Bronsted acid sites was predicted and shown to have superior performance in CH4 combustion.
NATURE COMMUNICATIONS
(2023)
Article
Chemistry, Physical
Nat Phongprueksathat, Kah Wei Ting, Shinya Mine, Yuan Jing, Ryo Toyoshima, Hiroshi Kondoh, Ken-ichi Shimizu, Takashi Toyao, Atsushi Urakawa
Summary: Low temperature and high pressure are advantageous conditions for achieving high conversion and selectivity in CO2 hydrogenation. Re/TiO2 has been identified as a promising catalyst with higher activity than the industrial Cu/ZnO/Al2O3 catalyst at high pressure and low temperature. The study provides insights into the nature of active sites and active species, demonstrating the active role of cationic Re species in CO2 activation and formate intermediate formation.
Article
Chemistry, Physical
Hiroe Kubota, Yuan Jing, Li Wan, Jiahuan Tong, Ningqiang Zhang, Shinya Mine, Takashi Toyao, Ryo Toyoshima, Hiroshi Kondoh, Davide Ferri, Ken-ichi Shimizu
Summary: In this study, operando spectroscopies were used to investigate the selective catalytic reduction of NO with NH3 over WO(3)-loaded CeO2. The reduction/oxidation half-cycles were elucidated through in situ Ce and W L-3-edge X-ray absorption near-edge structure, UV-vis, and infrared spectroscopies. The Ce4+ species were reduced by NO + NH3 to yield N-2 and Ce3+ species in the reduction half-cycle, which were then reoxidized by O-2 in the oxidation half-cycle. The oxidation state of the W(6+) species remained unchanged under redox conditions. IR and theoretical results suggested that the reduction half-cycle started with the reaction of W6+-OH and adjacent Ce(4+)-O with NO to afford Ce3+ species and gaseous HONO, which was then converted to NO+ species on the catalyst. The NO+ species reacted with NH3 to generate N-2.
Article
Chemistry, Physical
Mengwen Huang, Tetsuya Kinjo, Shunsaku Yasumura, Takashi Toyao, Daiju Matsumura, Hiroyuki Saitoh, Ken-ichi Shimizu, Norikazu Namiki, Zen Maeno
Summary: This study investigates the catalytic performance of Ga-exchanged zeolites at actual operating temperatures using in situ analysis. The results show that Ga-exchanged zeolites exhibit higher absorption peak intensity under hydrogen and ethane atmospheres, indicating the importance of hydride species in their catalytic activity.
CATALYSIS SCIENCE & TECHNOLOGY
(2023)
Article
Chemistry, Physical
Mengwen Huang, Yosuke Tomimuro, Shinta Miyazaki, Shinya Mine, Takashi Toyao, Yoyo Hinuma, Yasuharu Kanda, Masaaki Kitano, Ken-ichi Shimizu, Zen Maeno
Summary: This study investigated propane metathesis reactions over group 2-5 metal hydrides, with TiH2 showing the highest butane formation. Fully-hydrogenated TiH2 was found to be more active than dehydrogenated TiH and Ti metal. Surface low-valent Ti species on TiH2 were involved in the propane metathesis reaction. This study represents the first example of carbon-carbon bond cleavage and catalytic formation over bulk metal hydrides.
CATALYSIS SCIENCE & TECHNOLOGY
(2023)
