Effect of reduction on the performance of CoFe/SBA-15 catalysts for Fischer-Tropsch synthesis

CoFe/SBA-15 catalysts for Fischer-Tropsch synthesis were treated in different reduction atmosphere. It was found that the reduction in H₂ favored the formation of hexagonal cobalt, and then their catalytic activities were determined by the reduction of cobalt oxide. The presence of Fe₃O₄ promoted the water gas shift reaction, thus CO₂ selectivity increased with the increase of iron content. Compared with the catalysts reduced in H₂, the pretreatment in CO led to carbon deposition on cobalt active sites and lowered catalytic activities, but it facilitated the reduction of iron catalysts and led to the increase of olefin to paraffin ratio for C_2～4 hydrocarbons. Among them, 20Fe/SBA-15 catalyst showed high activity due to the formation of iron carbides.