Effect of SiO 2 content on iron-based catalysts for slurry Fischer–Tropsch synthesis

Abstract

A study has been carried out to investigate the effects of binder SiO 2 content on catalytic behavior of spray-dried precipitated Fe/Cu/K/SiO 2 catalysts for Fischer–Tropsch synthesis (FTS). The catalysts were characterized by means of N 2 physisorption, H 2 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 SiO 2 content stabilizes Fe 3O 4 phase and suppresses the further reduction and carburization of the catalysts in syngas. Long time on stream FTS performances showed that the catalyst with SiO 2 improves its reaction stability. The selectivities to light hydrocarbons (methane, C 2–C 4, C 5–C 11) are enhanced whereas those to heavy hydrocarbons (C 12 +) are suppressed with increasing SiO 2 content. The results were explained to the interactions of Fe–SiO 2 and K–SiO 2. From the present study, it is found that a catalyst with composition of 100Fe/5Cu/4.2K/25SiO 2 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.