CO2 HYDROGENATION OVER BASIC OXIDE-MODIFIED Al2O3 SUPPORTED COBALT CATALYSTS

Abstract

Basic oxides including MgO, CaO and La2O3 oxides were used to modify the properties of Al2O3 supported cobalt catalysts (15 wt% Co) in this study. The catalysts were prepared by the incipient wetness impregnation method of cobalt precursor onto the alumina supports. The catalysts were characterized by several techniques including XRD, BET, SEM, TEM, NH3-TPD, H2-TPR and H2-chemisorption. It was found that the reduction behaviors of cobalt species on the alumina supports were altered by the basic oxide modification. The TPR results showed that the addition of MgAl and La promoters could suppress the strong interaction between cobalt metal and the alumina support leading to the improvement of reducibility of the cobalt catalysts hence higher catalytic activity in CO2 hydrogenation were obtained. However, the addition of excessive amount of Mg with high calcination temperature of the magnesium modified alumina support brought about the formation of magnesium aluminate spinel (MgAl2O4), which resulted in lower reducibility and lower catalytic activity in the CO2 hydrogenation.