Study of Co/SB A-15 catalysts prepared by microwave and conventional heating methods and application in Fischer-Tropsch synthesis

摘要

The aim of this work was to produce a 20% (w/w) cobalt catalyst supported in SBA-15 molecular sieve, analyze it and evaluate its use in Fischer-Tropsch (FT) reaction. Two synthesis methods for the SBA-15 molecular sieves were evaluated: microwave (Co/SBA15-MW) and conventional heating (Co/SBA15-CH). The Co/SBA-15 catalysts were prepared by humidity impregnation and were characterized by X-ray diffraction, X-ray energy dispersion spectrophotometer, N2 adsorption-desorption, temperature-programmed reduction, and transmission electron microscopy. Fischer-Tropsch synthesis was carried out to evaluate the activity of the catalyst. The synthesis was carried out in a slurry reactor operating at 513 K, 20atm, and 1:1 CO:H2 molar ratio. X-ray diffraction showed that the calcined cobalt catalyst did not modify the structure of SBA-15 and that Co was present under the form of Co3O4 in the precursor. The addition of cobalt in the SBA-15 decreased the specific surface area of the molecular sieve. Fischer-Tropsch synthesis activity and C_(5+) hydrocarbon selectivity increased with the Co/SBA15-MW. The increase in activity and selectivity were attributed to the increased number of active sites as a result of the higher reducibility. The Co/SBA-15 catalysts showed moderate conversion (40%) and high selectivity towards the production of C5+ (79%, w/w).