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

Keiichi Tomishige, Kiyotaka Asakura, Yasuhiro Iwasawa

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64 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 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.

Original languageEnglish
Pages (from-to)70-80
Number of pages11
JournalJournal of Catalysis
Volume149
Issue number1
DOIs
Publication statusPublished - 1994 Jan 1
Externally publishedYes

ASJC Scopus subject areas

  • Catalysis
  • Physical and Theoretical Chemistry

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