Promoter Effect on the Physico-Chemical Properties of Cobalt Based Catalyst for CO Hydrogenation

摘要

The effects of modification with promoters (Ru, Zr, Mn and K) on the properties of cobalt-based catalyst in CO hydrogenation were investigated by TPSR technique. The catalysts prepared by sol-gel method were characterized by BET, TPR and H2-TPD. The effect of promoters was observed to have a profound impact on the physicochemical and catalytic properties of catalysts. Addition of Ru, K and Zr promoters to 30Co/MgO (30CM) facilitates the reducibility of catalyst. Mn addition improves the dispersion of metal clusters leading to a decrease in average cobalt crystallite size. Among all catalysts, 30Co-Mn/MgO (30CMM) and 30Co-Ru/MgO (30CRM) demonstrate the high reactivity and the maximum rate for methane formation. This could be attributed to the improvement of carbon monoxide chemisorption on high metal surface area of 30CMM and 30CRM catalyst. The change in physical and chemical properties of catalysts could be elaborated by the structural and electronic effects of promoter. Manganese effectively promotes cobalt supported magnesia catalyst by enhancement the C_(5+) selectivity.