Fischer-Tropsch synthesis on cobalt/Al₂O₃-modified SiC catalysts: Effect of cobalt-alumina interactions

The effects of Al₂O₃ modification of the beta-SiC support on Fischer-Tropsch synthesis (FTS) catalysts were investigated in terms of the dispersion of cobalt particles through different metal support interactions for higher CO conversion and stability. The SiC support was previously modified using a alumina precursor with 0-15 wt% in order to increase the surface area and to enhance a dispersion of Co₃O₄ particles. The alumina-modified SiC support at an optimal amount of Al ₂O₃ showed higher catalytic performance and stability compared with the unmodified Co-SiC catalyst. The optimum concentration of alumina for higher catalytic performance is found to be around 10 wt% Al ₂O₃ on the SiC support. The observed higher CO conversion and stability are mainly attributed to the formation of adjacent cobalt-alumina complexes through an increase of cobalt dispersion and the enhanced interactions between cobalt and alumina particles. The enhanced interactions of cobalt-alumina are also responsible for a lower aggregation of metallic cobalt particles by forming smaller cobalt particles around 13 nm in size, which was confirmed using X-ray photoelectron spectroscopy, temperature-programmed reduction and TEM analyses mainly.