Fischer–Tropsch synthesis over the Fe–Mn/Al2O3 catalyst: modeling and optimization of light olefins using the RSM method

Abstract

Fe–Mn/Al₂O₃ catalysts were prepared via a co-precipitation procedure and used for light olefin production via a CO hydrogenation reaction. The effect of preparation parameters including the precipitation ageing time, pH and temperature on the catalytic performance has been investigated. The ageing time was changed from 60 to 300 min, the precipitation pH was changed from 6.5 to 10.5 and the precipitation temperature was investigated in the range of 40–80 °C. Modeling and optimization processes were performed using response surface methodology (RSM). Polynomial equations for each response were successfully fitted to the experimental data. According to the optimization results the best preparation conditions were found to be aageing time = 160 min, pH = 8.78 and precipitation temperature = 74.16 °C. At these optimized conditions the maximum selectivity toward (C₂–C₄) light olefins and CO conversion% and minimum selectivity toward methane were achieved. The effect of the preparation parameters was also investigated on the various surface reaction rates. Catalyst characterization was performed using XRD, BET, TGA, DSC and SEM.