The effect of syngas composition on the Fischer Tropsch synthesis over three-dimensionally ordered macro-porous iron based catalyst

Abstract

Three-Dimensionally Ordered Macro-porous (3DOM) Fe based catalysts were synthesized via a facile “glyoxylate route” poly (methyl methacrylate) (PMMA) colloidal crystal template (CCT) method. Fischer Tropsch Synthesis (FT) using different biosyngasses over the 3DOM Fe based catalyst for producing the liquid hydrocarbon was studied. The morphology, structure and microstructures of 3DOM Fe based catalysts were characterized by SEM, BET, TPR, HRTEM, XRD, XPS and DRIFTS. The experimental results demonstrated that the hydrogen lean syngas decreased the partial pressure of H2/CO, which caused the decrease of the CO conversion rate during FT reaction. Moreover, the addition of CO2 and CH4 in the hydrogen lean syngas could well preserve the iron carbide phase in the catalyst, and the CO conversion rate was improved. Lower H2/CO ratio syngas would shift the liquid hydrocarbon distribution to higher molecular weight hydrocarbons, and the addition of CO2 and CH4 into the syngas further facilitated the shift. Meanwhile, it was also found that the CO conversion rate and C5+ selectivity were 68.23% and 70.44% respectively during the simulated biosyngas from biomass gasification (the hydrogen lean syngas contained CO2 and CH4) FT over the 3DOM Fe based catalyst, and CO2 and CH4 selectivity were 12–26% and 2.67–5.5% respectively.