In situ Fourier-transform infrared studies of CO–H2 reactions over Ru–Rh/SiO2 catalysts at high pressure and temperature

Abstract

Infrared spectra of Ru–Rh/SiO₂ catalyst in situ in CO–H₂ mixtures (ratios 1 : 14, 1 : 2 and 14 : 1) at high pressure (0.3, 1.5 and 3 MN m^–2) and temperature (473, 503, 553 K) are compared with corresponding results for Rh/SiO₂ and Ru/SiO₂. The mixed metal catalyst gave results suggesting that the surfaces of the metallic particles contained primarily Rh rather than Ru atoms, a conclusion which was substantiated by data for the adsorption of CO and methanol or ethanol. Particles possibly consisted of a monoatomic sheath of Rh surrounding a core of Ru. The nature of the precursor metal salts probably has a strong influence on the structures of individual metal particles after reduction.