Synthesis of SiO2-stabilized FeMn catalysts for catalytic production of liquid fuels: effect of SiO2 position over bimetallic catalysts

Fischer-Tropsch synthesis (FTS) is a non-petroleum-based alternative route for direct production of liquid fuels. Promoters are required to attain optimum catalytic performance; however, the strong metal-promoter interaction limits the catalytic activity. To optimize the selectivity-promoting property, two different SiO2-stabilized core-shell catalysts were designed via tuning the position of SiO2 shell. Clearly, the research on SiO2-stabilized and Mn-promoted core-shell catalyst is still insufficient. It demonstrates that the C5+ yield over SiO2-incorporated FeMnSi (13.7 × 10−4 gHCgFe−1s−1) and FeSiMn (20.8 × 10−4 gHCgFe−1s−1) is higher than that of unstabilized FeMn catalyst (2.85 × 10−4 gHCgFe−1s−1). Interestingly, the CO conversion over the three catalysts obeys the following role: FeSiMn > FeMnSi > FeMn. The better C5+ production with high catalytic activity over FeSiMn is correlated with the critical role of Mn-improved spillover effect. This is because the formed MnFe2O4 over FeMnSi and FeMn catalyst limits the initial catalytic performance, and that can gradually suppress CO dissociation and hinder chain growth. Controlling the metal-promoter interaction in FT synthesis can better understanding and rational design of a catalyst with enhanced catalytic performance.