Selective Production of C4 Hydrocarbons from Syngas Using Fe-Co/ZrO2 and SO4 2–/ZrO2 Catalysts

Modified Fischer-Tropsch (MFT) syntheses were carried out to convert synthesis gas to C4 hydrocarbons over Fe-Co/ZrO2 (FT) and SO42–/ZrO2 (SZ) catalysts in a dual reactor system, keeping the FT to SZ catalysts ratio at 1:1.5. Five Fe-Co/ZrO2 catalysts with different Fe and Co loading, and SZ with 15 wt% SO42– were prepared and extensively characterized using various physico-chemical methods. The FT synthesis process was initially performed using a Fe-Co/ZrO2 catalyst in a single reactor and the effects of Fe and Co mass ratio, reaction temperature, space velocity on the production of C4 hydrocarbons and C2-C4 olefins were investigated. Results indicated that a 3.71% Fe–8.76% Co/ZrO2 mixed oxide catalyst alone at 260° C and 5 h–1 gave high selectivities of C2-C4 olefins (~26.1 wt%) and total C4 hydrocarbon product (~16.2 wt%). The MFT process 150°C gave higher C4 (~31.6 wt%), isobutane (~22.9 wt%) and C2-C4 (31.1 wt%) selectivities.