Ethane hydrogenolysis on silica-supported RhAg catalysts

Abstract

Several series of silica-supported RhAg catalysts have been characterized by nitrogen adsorption (BET), hydrogen and carbon monoxide chemisorption, X-ray diffraction line-broadening analysis, and X-ray photoelectron spectroscopy (XPS). The two metals are shown to interact and, based on the chemisorption and XPS results, the catalysts are modeled as small crystallites of Rh with Ag deposited on the surface in a thin layer, perhaps only one atom thick. While chemisorption of hydrogen and carbon monoxide decreases as the Ag/Rh ratio increases, the rate of specific ethane hydrogenolysis is nearly constant. This is interpreted in terms of the manner in which Ag is deposited on the Rh crystallites, i.e., it forms islands of complete coverage and leaves patches of bare Rh.