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