Abstract
Energy conversion, energy efficiency and the study of producing liquid fuels from other carbon resources are getting an increasing attention, as the continue depletion of oil. In this paper, SiO2-encapsulated Fe@Mn catalysts were prepared by Stöber method and applied for the production of olefins-riched liquid fuels from syngas. With the thickening of SiO2 shell, the selectivity for liquid hydrocarbons (C5+) presents a volcanic trend, which is the result of the balancing effect between hydrogen enrichment and spatial restriction of SiO2 shell. The promotional effect of SiO2 shell on the formation of C5+ can be attributed to the confinement effect of SiO2 shell, which prolongs the residence time of light hydrocarbons formed on Fe@Mn, enhancing the polymerization reaction for producing more C5+ hydrocarbons. The C5+ selectivity can reach 72% with 78% olefins in it, at CO conversion of 67%. However, the continued increase in the thickness of SiO2 shell may lead to the enrichment of H2 and increase the local H2/CO ratio in the vicinity of the active metal, enhancing the hydrogenation reaction and suppressing the formation of C5+ hydrocarbons.
Keywords Energy Conversion, Liquid Fuels, Olefins, Sio2 Shell, Fischer-Tropsch Synthesis
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