Design and characterization by EXAFS, FTIR, and TEM of Rh-Sn/SiO{sub 2} catalysts active for NO-H{sub 2} reaction

Journal Article · Thu Sep 01 04:00:00 EDT 1994 · Journal of Catalysis

DOI:https://doi.org/10.1006/jcat.1994.1273· OSTI ID:110978

Tomishige, Keiichi; Asakura, Kiyotaka; Iwasawa, Yasuhiro ^[1]

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1. Univ. of Tokyo (Japan)

Rh-Sn/SiO{sub 2} catalysts, prepared by the selective reaction between Sn(CH{sub 3}){sub 4} and small Rh metallic particles supported on SiO{sub 2}, showed much higher catalytic activities for NO-H{sub 2}reaction and NO dissociation than Rh/SiO{sub 2} and coimpregnation Rh-Sn/SiO{sub 2}. In order to examine the important factors for the efficient catalysis of the Rh-Sn/SiO{sub 2} catalysts, the samples were characterized by Sn K- and Rh K-edge EXAFS, FTIR, H{sub 2} and Co adsorption, and TEM. For the Rh-Sn/SiO{sub 2} catalysts (Sn/Rh{ge}0.4), the surface concentration of Sn to Rh was estimated to be Sn{sub s}/Rh{sub 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 nm, 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 SiO{sub 2} as a catalytically active bimetallic ensemble is discussed. 34 refs., 8 figs., 4 tabs.

• OSTI ID: 110978
• Journal Information: Journal of Catalysis, Journal Name: Journal of Catalysis Journal Issue: 1 Vol. 149; ISSN 0021-9517; ISSN JCTLA5
• Country of Publication: United States
• Language: English

Related Subjects

40 CHEMISTRY
ABSORPTION SPECTROSCOPY
CATALYST SUPPORTS
CATALYSTS
CATALYTIC EFFECTS
HYDROGENATION
NITRIC OXIDE
RHODIUM
SILICA
STRUCTURAL CHEMICAL ANALYSIS
TIN
X-RAY SPECTROSCOPY