Alcohol synthesis by catalytic hydrogenation of CO2 over Rh-Co/SiO2

The effect of the cobalt additive on Rh/SiO2 catalysts prepared by co-impre gnation was examined to improve the reactivity in CO2 hydrogenation. The CO 2 conversion increased significantly with the amount of cobalt added. Altho ugh the methanol selectivity was very low over nonpromoted Rh/SiO2 catalyst , more than 10% selectivity to methanol was obtained over the catalysts wit h cobalt added in the range of Co/Rh=0.1-1 (atomic ratio). The methanol yie ld over Rh-Co/SiO2 catalyst was higher than the sum of the yields of Rh/SiO 2 and Co/SiO2 catalysts, Physically mixed Rh/SiO2 and Co/SiO2 catalysts did not promote methanol formation. Based on the results of X-ray diffraction and. Xray photoelectron spectroscopy, it was suggested that Ph-Co alloy was formed on the catalyst surface to change the electronic states of rhodium, resulting in promotion of methanol formation. Copyright (C) 2000 John Wile y & Sons, Ltd.