Fischer–Tropsch synthesis of liquid hydrocarbons over mesoporous SBA-15 supported cobalt catalysts

Abstract

The influence of cobalt loading (10–30 wt% Co) and pore size of SBA-15 support on the physico-chemical and catalytic performance of mesoporous Co/SBA-15 catalysts for the Fischer–Tropsch synthesis (FTS) reaction (T = 245 °C, P = 290 psig, H₂/CO = 2, and GHSV = 2000 h⁻¹) has been investigated. Catalysts were characterized by N₂ adsorption–desorption, X-ray diffraction (XRD), electron microscopy, and temperature-programmed reduction (TPR). The dispersion of Co/SBA-15 decreased and the extent of cobalt reduction increased with increasing either the cobalt loading or pore size of SBA-15. A maximum CO conversion was found for the sample with 20 wt% Co loading. More methane and less C₅₊ hydrocarbons were produced over less reducible 10 wt% Co loaded sample. The 20Co/SBA-15 catalysts with larger pores led to larger cobalt crystallite size, lower dispersion and higher reducibility. CO conversion increased with the increase of pore size in the range studied. The 20Co/SBA-15 catalysts with larger cobalt crystallite size showed higher C₅₊ selectivity for the FTS. Finally, at comparable Co loading, CO conversion of Co/SBA-15 catalysts were to be about 2 times greater than a Co/SiO₂ sample, with only a minor difference in product selectivity.