Effect of calcination temperature of support on catalytic performance of Co/ZrO2 for Fischer-Tropsch synthesis

Fischer-Tropsch (F-T) synthesis is of great importance in converting natural gas and coal to liquid fuel. One important focus in the development of this process is the improvement of catalyst activity with low CH4 selectivity. The effect of calcination temperature of ZrO2 support on the catalytic performance of Co/ZrO2 catalyst for F-T synthesis was studied in detail. ZrO2 support was prepared by coprecipitation and a series of ZrO2-supported cobalt-based catalyst samples were prepared by impregnation. The physico-chemical properties of the samples were characterized by BET, XRD, NH3-TPD and TPR. The catalytic performance of the catalyst was evaluated under the conditions of n(H-2)/n(CO) = 2.0, GHSV = 1000 h(-1), p = 2.0 MPa and theta = 210 similar to 220degreesC. The results indicated that the physico-chemical properties of the support were greatly influenced by calcination temperature. The acidity and acid amount of the support decreased with increasing calcination temperature, and the surface area decreased at the same time. Cobalt supported on strongly acidic ZrO2 support led to strong interaction between them, hence the catalyst was hard to be reduced and its catalytic activity for F-T synthesis decreased. The transformation of ZrO2 calcined at lower temperature from amorphous phase to tetragonal phase might be accelerated when cobalt was supported on, resulting in that the cobalt was well dispersed, but the catalytic activity and selectivity were poor.