Design and characterization by EXAFS, FTIR, and TEM of Rh-Sn/SiO2 catalysts active for NO-H2 reaction

Keiichi Tomishige; Kiyotaka Asakura; Yasuhiro Iwasawa

doi:10.1006/jcat.1994.1273

Design and characterization by EXAFS, FTIR, and TEM of Rh-Sn/SiO₂ catalysts active for NO-H₂ reaction

Keiichi Tomishige, Kiyotaka Asakura, Yasuhiro Iwasawa

Research output: Contribution to journal › Article › peer-review

65 Citations (Scopus)

Abstract

Rh-Sn/SiO₂ catalysts, prepared by the selective reaction between Sn (CH₃)₄ and small Rh metallic particles supported on SiO₂, showed much higher catalytic activities for NO-H₂ reaction and NO dissociation than Rh/SiO₂ and coimpregnation Rh-Sn/SiO₂. In order to examine the important factors for the efficient catalysis of the Rh-Sn/SiO₂ catalysts, the samples were characterized by Sn K- and Rh K-edge EXAFS, FTIR, H₂ and CO adsorption, and TEM. For the Rh-Sn/SiO₂ catalysts (Sn/Rh ≥ 0.4), the surface concentration of Sn to Rh was estimated to be Sn_s/Rh_s = 3, where a Rh atom is surrounded by six Sn atoms. According to the results of the Sn K-edge EXAFS analysis, the bond distance between a Sn atom and the nearest-neighbor atom in the first layer atoms was 0.270 nn, and the bond distance between a Sn atom and a metal atom in the second layer was 0.290 nm, suggesting a relaxation of the first bimetallic layer. A surface model structure of Rh-Sn particles on SiO₂ as a catalytically active bimetallic ensemble is discussed.

Original language	English
Pages (from-to)	70-80
Number of pages	11
Journal	Journal of Catalysis
Volume	149
Issue number	1
DOIs	https://doi.org/10.1006/jcat.1994.1273
Publication status	Published - 1994
Externally published	Yes

ASJC Scopus subject areas

Catalysis
Physical and Theoretical Chemistry

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title = "Design and characterization by EXAFS, FTIR, and TEM of Rh-Sn/SiO2 catalysts active for NO-H2 reaction",

abstract = "Rh-Sn/SiO2 catalysts, prepared by the selective reaction between Sn (CH3)4 and small Rh metallic particles supported on SiO2, showed much higher catalytic activities for NO-H2 reaction and NO dissociation than Rh/SiO2 and coimpregnation Rh-Sn/SiO2. In order to examine the important factors for the efficient catalysis of the Rh-Sn/SiO2 catalysts, the samples were characterized by Sn K- and Rh K-edge EXAFS, FTIR, H2 and CO adsorption, and TEM. For the Rh-Sn/SiO2 catalysts (Sn/Rh ≥ 0.4), the surface concentration of Sn to Rh was estimated to be Sns/Rhs = 3, where a Rh atom is surrounded by six Sn atoms. According to the results of the Sn K-edge EXAFS analysis, the bond distance between a Sn atom and the nearest-neighbor atom in the first layer atoms was 0.270 nn, and the bond distance between a Sn atom and a metal atom in the second layer was 0.290 nm, suggesting a relaxation of the first bimetallic layer. A surface model structure of Rh-Sn particles on SiO2 as a catalytically active bimetallic ensemble is discussed.",

author = "Keiichi Tomishige and Kiyotaka Asakura and Yasuhiro Iwasawa",

year = "1994",

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AU - Tomishige, Keiichi

AU - Asakura, Kiyotaka

AU - Iwasawa, Yasuhiro

PY - 1994

Y1 - 1994

N2 - Rh-Sn/SiO2 catalysts, prepared by the selective reaction between Sn (CH3)4 and small Rh metallic particles supported on SiO2, showed much higher catalytic activities for NO-H2 reaction and NO dissociation than Rh/SiO2 and coimpregnation Rh-Sn/SiO2. In order to examine the important factors for the efficient catalysis of the Rh-Sn/SiO2 catalysts, the samples were characterized by Sn K- and Rh K-edge EXAFS, FTIR, H2 and CO adsorption, and TEM. For the Rh-Sn/SiO2 catalysts (Sn/Rh ≥ 0.4), the surface concentration of Sn to Rh was estimated to be Sns/Rhs = 3, where a Rh atom is surrounded by six Sn atoms. According to the results of the Sn K-edge EXAFS analysis, the bond distance between a Sn atom and the nearest-neighbor atom in the first layer atoms was 0.270 nn, and the bond distance between a Sn atom and a metal atom in the second layer was 0.290 nm, suggesting a relaxation of the first bimetallic layer. A surface model structure of Rh-Sn particles on SiO2 as a catalytically active bimetallic ensemble is discussed.

AB - Rh-Sn/SiO2 catalysts, prepared by the selective reaction between Sn (CH3)4 and small Rh metallic particles supported on SiO2, showed much higher catalytic activities for NO-H2 reaction and NO dissociation than Rh/SiO2 and coimpregnation Rh-Sn/SiO2. In order to examine the important factors for the efficient catalysis of the Rh-Sn/SiO2 catalysts, the samples were characterized by Sn K- and Rh K-edge EXAFS, FTIR, H2 and CO adsorption, and TEM. For the Rh-Sn/SiO2 catalysts (Sn/Rh ≥ 0.4), the surface concentration of Sn to Rh was estimated to be Sns/Rhs = 3, where a Rh atom is surrounded by six Sn atoms. According to the results of the Sn K-edge EXAFS analysis, the bond distance between a Sn atom and the nearest-neighbor atom in the first layer atoms was 0.270 nn, and the bond distance between a Sn atom and a metal atom in the second layer was 0.290 nm, suggesting a relaxation of the first bimetallic layer. A surface model structure of Rh-Sn particles on SiO2 as a catalytically active bimetallic ensemble is discussed.

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