Highly active Co/SiC catalysts with controllable dispersion and reducibility for Fischer–Tropsch synthesis

Silicon carbide (SiC) supported Co catalysts (20 wt.% Co/SiC) were examined for Fischer–Tropsch synthesis in a fixed-bed reactor. It exhibited higher CO conversion and lower CH4 selectivity (75.3%, 8.2%) under the conditions of T = 493 K, P = 2 MPa, H2/CO = 2, compared with that of Co/SiO2 (61.5%, 10.5%) and Co/Al2O3 (37.3%, 12.1%) even though SiC has much lower surface area (60 m2/g) than SiO2 (154 m2/g) and Al2O3 (240 m2/g). The use of Co acetate as precursor instead of Co nitrate could not only improve Co dispersion but also obtain high reducibility of Co. Decrease of the reducibility is milder with decreasing Co crystal size on SiC. Characterization results indicate that Co sintering is one of the main reasons for the catalyst deactivation due to the weak Co–SiC interaction. ZrO2 addition can greatly improve the stability of Co/SiC catalyst, which is ascribed to suppressing the carbon deposition on Co and alleviating Co sintering.