Alumina Grafted to SBA-15 in Supercritical CO2 as a Support of Cobalt for Fischer–Tropsch Synthesis

Abstract

The impact of acidity and pore size on the activity and product selectivity of the Fischer–Tropsch (FT) synthesis was comparatively investigated over cobalt supported on a series of alumina-grafted siliceous SBA-15 (Al-SBA-15) via the post-synthesis method in the medium of supercritical CO2. X-ray diffraction (XRD) results indicate that the ordered mesoporous structure of SBA-15 is preserved after grafting different amounts of alumina. However, both the Brunauer–Emmett–Teller (BET) surface area and the pore volume of Al-SAB-15 are decreased with an increasing content of alumina. Ammonia temperature-programmed desorption (NH3-TPD) results indicate that the acidity of Al-SBA-15, which is dominantly contributed by weak acidic sites, increases continuously with an increasing content of alumina. The 20 wt % Co-supported catalysts prepared by the incipient impregnation method were evaluated for FT synthesis in a fixed-bed reactor under the conditions of 1.0 MPa, 235 °C, H2/CO = 2, and W/F = 5.02 g h mol–1. Sign...