Fischer-Tropsch Synthesis on SiC-Supported Cobalt Catalysts

摘要

Seven SiC supports provided by SICAT with different surface areas and pore volumes were impregnated with 12,5 wt% Co. H2-chemisorption, N2-adsorption, temperature programmed reduction and Fischer-Tropsch synthesis in a fixed-bed reactor at 483 K, 20 bar and H2/CO = 2.1 were performed in order to characterize and test the samples. The performances were compared with well characterized Co/Al2O3 and Co-Re/Al2O3 reference catalysts. The selectivity towards heavier hydrocarbons (C_(5+)) was found to be moderately higher for the SiC supported catalysts while the site-time yields was 20 to 66 % lower than the Co-Re/Al2O3 catalyst. Elemental analysis showed the presence of several impurities in the SiC material. Alkali and alkaline earth elements, such as Na, K and Ca, are all known to lower the catalytic activity and also to influence the selectivity. It is proposed that these impurities in addition to sulfur and phosphorus known to be present in SiC, are responsible for the significantly lower catalytic activity of the SiC supported catalysts.