Effects of reaction variables on Fischer-Tropsch synthesis with co-precipitated K/FeCuAlO _x catalysts

The effects of reduction temperature and reaction temperature, pressure and space velocity on iron-based K/FeCuAlO _x Fischer-Tropsch catalysts prepared by co-precipitation were investigated. The catalyst reduced at 150 °C deactivated quickly due to an abundance of unreduced iron species. With increasing reduction temperature, the iron oxide's phase transformed from hematite (α-Fe₂O₃) to magnetite (Fe ₃O₄) and finally to metallic iron (α-Fe). The induction period to reach steady-state catalytic activity was reduced at increased reduction temperatures due to in situ reduction by syngas during reaction. CO conversion increased with increasing reaction temperature, and selectivity to C₅+ decreased with increasing reaction pressure and space velocity. At reaction temperatures up to of 300 °C, CO₂ formation by the water-gas shift reaction was linearly correlated with the extent of CO conversion, and CO₂ formation was slightly suppressed at ≥350 °C by a reverse water-gas shift reaction. Graphical Abstract: The effects of reduction temperature and reaction temperature, pressure and space velocity on iron-based K/FeCuAlO_x Fischer-Tropsch catalysts prepared by co-precipitation were investigated. The catalyst reduced at 150 °C deactivated quickly due to an abundance of unreduced iron species. With increasing reduction temperature, the iron oxide's phase transformed from hematite (α-Fe₂O₃) to magnetite (Fe ₃O₄) and finally to metallic iron (α-Fe). The induction period to reach steady-state catalytic activity was reduced at increased reduction temperatures due to in situ reduction by syngas during reaction. CO conversion increased with increasing reaction temperature, and selectivity to C₅+ decreased with increasing reaction pressure and space velocity. At reaction temperatures up to of 300 °C, CO₂ formation by the water-gas shift reaction was linearly correlated with the extent of CO conversion, and CO₂ formation was slightly suppressed at ≥350 °C by a reverse water-gas shift reaction.[Figure not available: see fulltext.]