Hydrogenation of carbon monoxide and carbon dioxide over supported rhodium catalysts

Abstract

The formation of hydrocarbons in the reactions of CO + H 2 and CO 2 + H 2 was studied over rhodium catalysts supported on Nb 2O 2, ZrO 2, Al 2O 3, SiO 2 and MgO. Among these catalysts, Rh on Nb 2O 5 was most active in the reaction of CO + H 2 and RhMgO was least active. In the hydrogenation of CO 2, RhZrO 2 was more reactive than RhNb 2O 5 and showed measurable activity even at 50°C, in contrast to the inactivity at temperatures up to 130°C in the CO + H 2 reaction. The inverse kinetic isotope effect was observed in both reactions of Co + H 2(D 2) and CO 2 + H 2(D 2) over RhNb 2−O 5 and RhZrO 2. However, the isotope effect was not observed in the CO 2 reaction over RhAl 2O 3, whose effect in the CO reaction was still inverse. The mechanisms of the above reactions are correlated to the IR study of the adsorbed species.