Removal of residual CO from CO_2-rich hydrogenous gas via thermally differential methanation: principle and entailed challenge

摘要

Fischer-Tropsch synthesis (FTS) is a promising way to convert coal and natural gas to clean fuels and chemicals via syngas. Cobalt-based catalysts attract most of current attention in FTS because of their high activity, high selectivity for long chain paraffins, and low water gas shift activity. For cobalt based catalysts, the chemical and texture properties of the support influence the catalytic activity and product selectivity, via their modifications on the reducibility and dispersion of cobalt or the formation of well-fined phases. Synthesis of highly dispersed Co catalysts requires strong interaction between the support and the Co precursor, but in turn such strong interactions generally lower the reducibility of such precursors. To solve this problem, introduction of metal oxide to modify cobalt-support interaction of cobalt-based catalyst was studied. ZrO_2 addition to cobalt/silica was found to enhance the FTS activity significantly [1, 2]. Here we report that Al_2O_3 as well as TiO_2 also improved cobalt/silica FTS catalyst remarkably, acting as promoters.