Methanation of Carbon Monoxide with Water over Supported Rhodium Catalysts.

The formation of methane in the reaction of CO and H2O over Rh supported on ZrO2, Al2O3, TiO2, SiO2 and MgO was examined. The high activity was achieved over Rh/ZrO2 and Rh/TiO2 at 300°C and CO dissociation ability of the catalyst was concluded to be an important factor to obtain high activity. At low temperature (c. 200°C), CO was not hydrogenated effectively but CO2 formed by the water gas shift reaction was hydrogenated after the conversion of CO into CO2 was completed. The formation of CH4 appears to occur through the water gas shift reaction, followed by the hydrogenation of carbonaceous species formed by the dissociation of CO or CO2.