Effect of SiO2 content on iron-based catalysts for slurry Fischer–Tropsch synthesis

A study has been carried out to investigate the effects of binder SiO2 content on catalytic behavior of spray-dried precipitated Fe/Cu/K/SiO2 catalysts for Fischer–Tropsch synthesis (FTS). The catalysts were characterized by means of N2 physisorption, H2 temperature-programmed reduction (TPR), scanning electron microscopy (SEM), and Mössbauer effect spectroscopy (MES). The Fischer–Tropsch synthesis performances (activity, selectivity and stability) of the catalysts were studied in a slurry-phase continuously stirred tank reactor (CSTR). The results indicated that the increase of SiO2 content stabilizes Fe3O4 phase and suppresses the further reduction and carburization of the catalysts in syngas. Long time on stream FTS performances showed that the catalyst with SiO2 improves its reaction stability. The selectivities to light hydrocarbons (methane, C2–C4, C5–C11) are enhanced whereas those to heavy hydrocarbons (C12+) are suppressed with increasing SiO2 content. The results were explained to the interactions of Fe–SiO2 and K–SiO2. From the present study, it is found that a catalyst with composition of 100Fe/5Cu/4.2K/25SiO2 on mass basis displays both better FTS performances and a good attrition resistance, which is suitable for the use in CSTRs or SBCRs (Slurry Bubble Column Reactors) for FTS reaction.