Effect of lanthanum doping on the lifetime of Co/γ-Al2O3 catalysts in Fischer-Tropsch synthesis

Abstract

Cobalt-based catalysts were prepared on gamma alumina supports, and their behaviour for different Fischer-Tropsch synthesis (FTS) conditions was assessed. Although Co/γ-Al2O3 is a well-known FTS catalyst, its durability ought to be improved to make the industrial process economically feasible. The effect of lanthanum doping on the catalyst lifetime was examined utilising reactor tests and catalyst characterization techniques including TPR, ICP and N2 porosimetry. Reactor test results revealed that an optimum amount of lanthanum improved catalyst activity and selectivity. Increasing amounts of lanthanum doping up to about 1.1wt% seemed to modify the chemical composition of the support resulting in improved catalyst selectivity and lifetime. Further increase in lanthanum doping up to 2.7wt% only marginally enhanced the catalyst selectivity and lifetime. TPR results revealed that the high temperature peak due to cobalt aluminate phase shifted to lower temperatures with increasing amount of doped lanthanum possibly due to the formation of lanthanum/aluminium mixed oxides.