CO2 reforming of methane over vanadia-promoted Rh/SiO2 catalysts

Abstract

The reforming of methane with carbon dioxide over rhodium dispersed on silica, Rh/SiO2, and vanadia-promoted silica, Rh/VOx/SiO2, was studied by kinetic test reactions under differential conditions in a temperature range from 723 to 773 K. Transmission infrared spectroscopy was applied to observe the interaction of CO2 with the catalysts and the formation of surface intermediates during the CO2–CH4 reforming reaction. To analyze carbon deposition XP spectroscopy and TPO was carried out. It has been shown that the promotion of Rh/SiO2 catalysts with vanadium oxide enhances the catalytic activity for CO2 reforming of methane and decreases the deactivation by carbon deposition. This is attributed to the formation of a partial VOx overlayer on the Rh surface, which reduces the size of accessible ensembles of Rh atoms required for coke formation and creates new sites at the Rh–VOx interfacial region that are considered to be active sites for the activation/dissociation of carbon dioxide.