Constructing efficient hcp-Co active sites for Fischer-Tropsch reaction on an activated carbon supported cobalt catalyst via multistep activation processes

摘要

A highly efficient activated carbon supported cobalt based catalyst for Fischer-Tropsch synthesis was constructed. The catalyst was prepared by incipient wetness co-impregnation. The obtained catalyst was activated by multistep activation processes, which was composed of reduction of calcined sample in H2, syngas treatment, carburization in CO, and re-reduction in H2 successively. The multistep activation processes derived catalyst (CoZr/AC-RSCR) demonstrated far higher CO conversion and lower CH4 selectivity than those of conventional H2 reduction derived catalyst (CoZr/AC-R). The excellent performance of CoZr/AC-RSCR catalyst resulted from its higher amount of exposed active sites and the dominant hexagonal closed-packed (hcp) metallic cobalt phases. Furthermore, the catalytic performance could be further improved by tuning the content of hcp metallic cobalt phase stacking using the proper and effective treatment conditions of the multistep activation method. Finally, extremely high productivity of the mixture of alcohols and hydrocarbons with carbon number larger than 5 (194.6 g/h?kg-cat.) was acquired over CoZr/AC catalyst.