研究者詳細 - 沢邊　恭一

論文 - 沢邊　恭一

分割表示 66 件中 21 - 40 件目／全件表示 >>

Effects of carbon number and bond saturation on hydrocarbon combustion over a diesel oxidation catalyst

Tsuchiya, A; Masaoka, S; Ohyama, J; Sawabe, K; Satsuma, A

CATALYSIS SCIENCE & TECHNOLOGY 10 巻 ( 12 ) 頁： 3868 - 3874 2020年6月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Catalysis Science and Technology

One of the problems in a diesel oxidation catalyst is its insufficient activity for injected diesel fuel at low temperatures caused by strong adsorption of hydrocarbons. This study systematically clarified the poisoning effect of various hydrocarbons having carbon numbers from 3 to 16. As the carbon number in alkanes increased, the light-off temperature over a Pt-Pd/Al2O3 catalyst gradually shifted to a lower temperature. While alkenes and aromatics showed an opposite trend, the light-off shifted to a higher temperature as the carbon number increased. In situ FTIR spectra indicated that the amount of adsorbed hydrocarbons on the metal surface increased with the increase in the carbon number of alkanes and alkenes. Kinetic analysis showed that the reaction orders with respect to O2 were below zero in light alkane combustion, while those with respect to hydrocarbons were zero or lower in alkene and aromatic combustion. The shift of the light-off temperatures was rationalized by competitive adsorption of hydrocarbons and oxygen. This journal is

DOI： 10.1039/d0cy00017e

Web of Science

Scopus

Selective Hydrogenation of Cinnamaldehyde over the Stepped and Plane Surface of Pd Nanoparticles with Controlled Morphologies by CO Chemisorption

Murata, K; Ogura, K; Ohyama, J; Sawabe, K; Yamamoto, Y; Arai, S; Satsuma, A

ACS APPLIED MATERIALS & INTERFACES 12 巻 ( 23 ) 頁： 26002 - 26012 2020年6月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ACS Applied Materials and Interfaces

Carbon monoxide (CO) molecules are attracting attention as capping agents that control the structure of metal nanoparticles. In this study, we aimed to control the shape and surface structure of Pd particles by reducing the supported Pd precursor with CO. The reduction of Pd nanoparticles with CO promoted the exposure of step sites and generated spherical and concave-tetrahedral Pd particles on carbon and SiO2 supports. On the other hand, conventional H2-reduced Pd particles show a flattened shape. The preferential exposure of the step sites by the adsorbed CO molecules was supported by the density functional theory-calculated surface energy and the Wulff construction. Morphology- and surface-controlled Pd nanoparticles were used to study the surface structure and morphology effects of Pd nanoparticles on cinnamaldehyde (CAL) hydrogenation. With an increase in the fraction of step sites on Pd nanoparticles, the hydrogenation activity and selectivity of hydrocinnamaldehyde (HCAL) increased. On step sites, the adsorption of the C-C bond of CAL proceeded preferentially, and HCAL was efficiently and selectively generated.

DOI： 10.1021/acsami.0c05938

Web of Science

Scopus

PubMed

Structure-Activity Relationship of Iron Oxides for NO Reduction in the Presence of C3H6, CO, and O2

Ueda, K; Ohyama, J; Sawabe, K; Satsuma, A

CHEMISTRY-A EUROPEAN JOURNAL 25 巻 ( 61 ) 頁： 13964 - 13971 2019年11月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Chemistry - A European Journal

Spinel-type NiFe2O4 exhibited the highest NO reduction activity among base-metal oxides under simulated exhaust of a gasoline-powered vehicle. The structure–activity relationship of iron oxides has been investigated through both experimental and computational studies. Spinel iron oxide (γ-Fe2O3) exhibited a much higher NO reduction activity than that of iron oxide with other structures (α-Fe2O3 and LaFeO3). Operando IR measurements clarified that the spinel structure facilitated the reaction between NOx and adsorbed oxidized hydrocarbon or cyanide species. The high reactivity of the spinel structure was ascribed to the high adsorption energy of NO, as elucidated by DFT calculations. Furthermore, molecular orbital calculations demonstrated that the local coordination structure of the spinel iron oxide induced the involvement of not only σ but also π orbitals during NO adsorption on Fe atoms. This work clarified the origin of the structure-dependent activity of metal oxides, with a focus on their local coordination structures.

DOI： 10.1002/chem.201902994

Web of Science

Scopus

PubMed

金属酸化物とバイメタルで開拓する非貴金属自動車触媒招待有り

植田格弥,馬原優治,大山順也,沢邊恭一,薩摩篤

ファインケミカル 48 巻 ( 4 ) 頁： 31-37 2019年4月

Synthesis of Supported Bimetal Catalysts using Galvanic Deposition Method

Mahara, Y; Ohyama, J; Sawabe, K; Satsuma, A

CHEMICAL RECORD 18 巻 ( 9 ) 頁： 1306 - 1313 2018年9月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Chemical Record

Supported bimetallic catalysts have been studied because of their enhanced catalytic properties due to metal-metal interactions compared with monometallic catalysts. We focused on galvanic deposition (GD) as a bimetallization method, which achieves well-defined metal-metal interfaces by exchanging heterogeneous metals with different ionisation tendencies. We have developed Ni@Ag/SiO2 catalysts for CO oxidation, Co@Ru/Al2O3 catalysts for automotive three-way reactions and Pd−Co/Al2O3 catalysts for methane combustion by using the GD method. In all cases, the catalysts prepared by the GD method showed higher catalytic activity than the corresponding monometallic and bimetallic catalysts prepared by the conventional co-impregnation method. The GD method provides contact between noble and base metals to improve the electronic state, surface structure and reducibility of noble metals.

DOI： 10.1002/tcr.201700084

Web of Science

Scopus

PubMed

A Theoretical Insight into Enhanced Catalytic Activity of Au by Multiple Twin Nanoparticles 招待有り査読有り

Kyoichi Sawabe, Taiki Koketsu, Junya Ohyama and Atsushi Satsuma

Catalysts 7 巻頁： 191 2017年6月

A Theoretical Insight into Enhanced Catalytic Activity of Au by Multiple Twin Nanoparticles 査読有り Open Access

Sawabe, K; Koketsu, T; Ohyama, J; Satsuma, A

CATALYSTS 7 巻 ( 6 ) 2017年6月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Catalysts

Recently, it has been reported that the morphology of Au nanoparticles (NPs) affects the catalytic activity of CO oxidation; twin crystal NPs show higher activity for CO oxidation than single-crystal NPs. In this study, density functional calculations have been carried out to investigate the morphology effect of Au NPs using CO as a probe molecule. In the case of Au NPs with a size of more than 2 nm, CO adsorption energy on the Au NPs is mainly determined by a coordination number (CN) of adsorption sites. CO binding to a multiple twin NP with a size of about 1 nm is stronger than that on a single-crystal NP with the same size. A simple CN explanation cannot be applied to the enhancement of CO binding to the small multiple twin NP. This enhancement is related to a deformation of the NP structure before and after CO adsorption. It is suggested that the multiple twin NP with a size of less than 1 nm, which shows the deformation upon CO adsorption, contributes to the higher activity for CO oxidation.

DOI： 10.3390/catal7060191

Open Access

Web of Science

Scopus

Ag-M (M: Ni, Co, Cu, Fe) bimetal catalysts prepared by galvanic deposition method for CO oxidation 査読有り

Yuji Mahara, Hiroyuki Ishikawa1, Junya Ohyama, Kyoichi Sawabe, Atsushi Satsuma

Catalysis Today 265 巻頁： 2-6 2016年

Substrate-Specific Heterogeneous Catalysis of CeO2 by Entropic Effects via Multiple Interactions 査読有り

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

ACS Catal. 5 巻頁： 20-26 2015年

Enhanced CO Oxidation Activity of Ni@Ag Core Shell Nanoparticles 査読有り

Yuji Mahara,Hiroyuki Ishikawa, Junya Ohyama,Kyoichi Sawabe,Yuta Yamamoto,Shigeo Arai,,Atsushi Satsuma

Chem. Lett. 43 巻頁： 910-912 2014年

Density-Functional Theoretical Study on the Role of Lewis and Brønsted Acid Sites on CeO2(110) Surfaces for Nitrile Hydration 査読有り

Kyoichi Sawabe , Yukio Yoshikawa, Atsushi Satsuma

Top. Catal. 57 巻頁： 1094-1102 2014年

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）

Hydration of cyanopyridine on CeO2(110) surfaces was studied using periodic DFT+U calculations.One of two adsorption modes of 2-cyanopyridine occurs with two-point interaction which causes substrate specificity. A catalytic cycle for the hydration of 2-cyanopyridine was proposed. Cooperativity of Lewis and Brønsted acid sites was found to stabilize the intermediates for the hydration.

DOI： 10.1007/s11244-014-0274-8

自動車排ガス浄化用Aｇクラスター触媒の開発と作用機構研究査読有り

清水研一，沢邊恭一，薩摩篤

触媒 54 巻頁： 228-234 2012年

自動車排ガス浄化用時の再生型Agナノクラスター触媒査読有り

清水研一，沢邊恭一，薩摩篤

化学工業 63 巻頁： 213-218 2012年

Hydration of nitriles to amides in water by SiO2-supported Ag catalysts promoted by adsorbed oxygen atom 査読有り

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

Appl. Catal. 421/422 巻頁： 114-120 2012年

Unique catalytic features of Ag nanoclusters for selective NOx reduction and green chemical reactions 招待有り査読有り

Ken-ichi Shimizu, Kyoichi Sawabe, Atsushi Satsuma

Catal. Sci. Technol. 1 巻頁： 331-341 2011年

Self-Regenerative Silver Nanocluster Catalyst for CO Oxidation 査読有り

Ken-ichi Shimizu, Kyoichi Sawabe, and Atsushi Satsuma

ChemCatChem 3 巻頁： 1290-1293 2011年

Density functional theory calculation on the promotion effect of H2 in the selective catalytic reduction of NOx over Ag-MFI zeolite 査読有り

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

153 巻頁： 90-94 2010年

Oxidant-Free Dehydrogenation of Alcohols Heterogeneously Catalyzed by Cooperation of Silver Clusters and Acid–Base Sites on Alumina 査読有り

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

Chem. Eur. J. 15 巻頁： 2341-2351 2009年

Mechanism of Helix Induction in Poly(4-carboxyphenyl isocyanide) with Chiral Amines and Memory of the Macromolecular Helicity and Its Helical Structures 査読有り

Yoko Hase, Kanji Nagai, Hiroki Iida, Katsuhiro Maeda, Noriaki Ochi, Kyoichi Sawabe, Koichi Sakajiri, Kento Okoshi, and Eiji Yashima

J. Am. Chem. Soc. 131 巻頁： 10719-10732 2009年

*Adsorption structure of thiophene on Si(100)-2x1 studied by scanning tunneling microscopy and densitity functional theory 査読有り

Naoki Isobe, Tsutomu Shibayama, Yuichiro Mori, Kosuke Shobatake, Kyoichi Sawabe

Chem. Phys. Lett. 443 巻頁： 347-351 2007年

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