The effects of promoters of K and Zr on the mesoporous carbon supported cobalt catalysts for Fischer-Tropsch synthesis

摘要

The mesoporous carbon supported cobalt catalyst (15%Co/MC) was found to be more active and selective to C5+ than the traditionally activated carbon supported one (15%Co/AC) for the Fischer-Tropsch synthesis (FTS). The addition of small amount of K _2O and ZrO _2 significantly affected the FTS behavior of 15%Co/MC. The addition of 1% K inhibited the FTS activity dramatically, while the addition of 3% Zr increased the FTS activity significantly. The addition of K _2O decreased the surface acidity while increased the surface basicity of 15%Co/MC, resulting in the increased heat of adsorption of CO and substantially decreased heat of adsorption of H _2 on Co. In contrast, the addition of ZrO _2 increased the surface acidity and heat of adsorption of H _2 on Co. The FTS activity was found to be related to the ratio of heats for the adsorption of CO and H _2 on the catalysts 15%Co/MC, 15%Co-1%K/MC and 15%Co-3%Zr/MC. The highest FTS activity was obtained on the catalyst with the heat ratio of 1.2.