Effect of vacuum impregnation on the performance of Co/SiO 2 Fischer-Tropsch catalyst

Abstract

Two silica-supported cobalt catalysts were prepared by incipient wetness impregnation under atmospheric and vacuum conditions. N 2 physisorption, H 2 chemisorption, XRD, SEM, TEM, XPS and H 2-TPR were used to characterize the catalysts. The results showed that the impregnation methods had an effect on the size, dispersion and reducibility of cobalt particles. Under vacuum conditions, cobalt-containing steeping liquor could penetrate into the inner pores of silica support and more bivalent cobalt oxides were formed in the Co 3O 4 crystallites. Furthermore, cobalt precursors were rarely inclined to agglomerate and the smaller cobalt particles were uniform on the support, which led to the higher activity of the Co/SiO 2 (B) catalyst than the normal one under the reaction conditions of 483-523 K, 1-2 MPa, gas hourly space velocity of 500-1000 h −1 and molar ratio of H 2/CO = 0.5-2.0.