Eco-friendly prepared iron-ore-based catalysts for Fischer-Tropsch synthesis

The iron-ore-based catalysts (IO-CAT) with catalytic properties similar to those of conventional precipitated iron-based catalysts (PFe-CAT) were successfully prepared through a combination of a wet-milling process and a wet impregnation method. This approach was much more economical and eco-friendly than a conventional precipitation technique in terms of the amounts of water and chemicals used and discharged. The IO-CAT exhibited higher surface area, a larger pore volume, and a smaller crystallite size than the unmodified iron ore samples (IO-U). In particular, the pore volume of IO-CAT was as large as that of PFe-CAT. Furthermore, the reducibility and surface basicity of IO-CAT were much higher than those of IO-U and comparable to those of PFe-CAT, which implies that a reduction promoter, Cu, and an alkali promoter, K, are used successfully to impregnate the well-developed pore structure of IO-CAT. As a result, the IO-CAT showed catalytic performance favorable for low-temperature Fischer-Tropsch synthesis (LT-FTS) using hydrogen-deficient syngas (H-2/CO = 1) in all aspects of CO conversion (75%), CO2 selectivity (43 C-mol%), and C5+ selectivity in hydrocarbons (71 wt%). The overall catalytic performance of IO-CAT was much greater than that of IO-U and comparable to that of PFe-CAT. This strongly demonstrates new potential for economical and eco-friendly preparation of iron-based catalysts for LT-FTS.