Studies On the La2O3-Doped Al2O3 Supported Cobalt Catalyst for Fischer-Tropsch Synthesis

Alumina was doped with lanthana, La2O3, by either impregnation or co-precipitation. The doped and undoped alumina were then used as supports for the preparation of cobalt catalysts by incipient wetness impregnation. The catalysts prepared were characterized by nitrogen adsorption-desorption, powder X-ray diffraction, hydrogen temperature programmed reduction, hydrogen temperature programmed desorption, O2-titration and diffuse reflectance infrared Fourier transform spectroscopy, and the catalytic properties for Fischer-Tropsch synthesis (FTS) has been evaluated. The results showed that La2O3 dopping affected the catalytic performance significantly. The catalyst with the La2O3-doped support prepared by co-precipitation showed better reducibility, activity and product selectivities. The higher ratio of the octahedral to tetrahedral cobalt species of the co-precipitated catalyst than the catalyst doped by impregnation might have caused the enhanced performance. The activity for adsorption of CO on the catalysts with different supports was consistent with the CO conversion for FTS. The presence of the hydrocarbonyl species, distinguished by its vibration feature, are directly related to the CO conversion and chain-growth.