Influence of gold promoter on Fischer Tropsch synthesis over Co/Al ₂O₃ catalysts

In order to enhance the catalytic activity of Alumina supported cobalt catalyst (Co/Al₂O₃) for Fischer Tropsch synthesis, 1.5 and 2.5 wt% Au promoted 10% Co/Al₂O₃ is synthesized by coprecipitation and impregnation methods. The synthesized catalysts are characterized using XRD, TPR, TGA and BET techniques while fixed bed micro reactor is used to evaluate the activity and selectivity of prepared catalysts. The results confirm that 1.5 wt% Au loading shows higher CO conversion and C₅₊ hydrocarbons selectivity along with decreased selectivity towards methane and lower hydrocarbons. It is proposed through TPR studies that Au addition enhances the reduction of cobalt oxide thereby increasing the number of active sites and hence catalytic efficiency. Additionally, an increase in pressure and reduced feed flow rate led to excessive hydrocarbons production and subsequent conversion of syngas, possibly due to extended contact time between catalyst and reactants.