Study of Iron-Based Catalysts Performance in Fischer–Tropsch Synthesis: Temperature and Promoter Effect

Abstract

The iron-based catalysts were prepared via wet-impregnation method. The composition of the final iron catalysts, regarding to the weight ratio is as follow 14%Fe/γ-Al₂O₃, 14%Fe/3%Cu/γ-Al₂O₃, 14%Fe/3%Sn/γ-Al₂O₃ and 14%Fe/3%Cu/1%Sn/γ-Al₂O_3. The catalysts were characterized using XRD, ICP, BET, H₂-TPR, FE-SEM and EDX techniques. The catalytic activity was evaluated in a fixed bed reactor under 2.0 MPa of pressure, H₂ : CO = 1 : 1, GHSV = 2 L h^–1 \({\text{g}}_{{{\text{cat}}}}^{{-1}}\), in the temperature range of 270–300°C. Then, the effect of temperature and promoters (Cu and Sn) on the catalyst performance was investigated. CO conversion and product selectivity were also calculated using the results of GC. The results showed that the Cu and Sn promoters increased the reduction rate of Fe₂O₃ by providing H₂ dissociation sites. Higher temperatures were also shown to change the CO conversion and product selectivity. The selectivity of both methane and C₂–C₄ hydrocarbons decreased while the selectivity of C₅₊ increased because of simultaneous use of Cu and Sn for promoting iron catalyst. Sn promoter increased FT and WGS activities.