Unexpected increase in C5 + selectivity at temperature rise in high pressure Fischer-Tropsch synthesis over Co-Al2O3/SiO2 catalyst

Abstract

The effect of process variables on selectivity of Fischer-Tropsch synthesis (FTS) over Co/SiO2 catalyst was studied in a fixed-bed reactor operating in gas recycle mode. The unusual increase in C5+ selectivity with temperature was found in FTS at 6MPa. Whereas at a moderate pressure (2MPa) the catalyst response on temperature was typical for FTS, i.e. increase in activity concurrent with decrease of C5+ selectivity, at high pressure the C5+ selectivity grew up in parallel with catalyst activity. Selectivity to C35+ hydrocarbons was in order of magnitude greater in the FTS at 6MPa compared to 2MPa.