Study on wax-free liquid fuels synthesis from H2-deficient syngas over Co-Mn/meso-ZSM-5 catalyst

Abstract

The rapid consumption of fossil resources and the grim environmental situation encourage the application of renewable and clean energy resources. Conversion of biomass, which is a kind of renewable, CO2 neutral as well as abundant reserves carbon containing resource, is significantly important. The production of fuels from biomass by means of gasification and Fischer-Tropsch synthesis is one of the most promising routes for industrial applications. The wax-free liquid fuels synthesis directly from H2-deficient syngas similar to bio-gas is highly advantageous for reducing investment and operating cost. Thus, the Mn-promoted meso-ZSM-5 supported cobalt catalyst was applied for the production of wax-free liquid fuels by catalytic H2-deficient syngas conversion in this study. The performance of the reaction was influenced obviously by Mn content. The cobalt dispersion increased with the addition of Mn, whereas the reduction degree decreased after Mn doping. Then, the balance between the dispersion and reduction degree led to the change in CO uptake followed a volcanic curve. The catalyst with moderate amount of Mn (1 wt%) had the suitable cobalt particle size and the maximum CO uptake. Thus, the highest CO conversion was obtained over Co-1Mn/meso-ZSM-5 catalyst thanks to its maximum exposed active sites. The appropriate amount of Mn addition also resulted in the decreasing of CH4 selectivity. The highest space time yield of liquid fuels was acquired over the Co-1Mn/meso-ZSM-5 catalyst from H2-deficient syngas conversion under the moderate conditions.