Fanshu Ding

Effect of SiO2-coating of FeK/Al2O3 catalysts on their activity and selectivity for CO2 hydrogenation to hydrocarbons

SiO2-coated FeK/Al2O3 catalysts with different silica content were prepared and examined for the synthesis of hydrocarbons from CO2 hydrogenation. It was found that SiO2 coating affects both the activity for CO2 conversion and the selectivity to higher hydrocarbons, depending on the loading level. The catalyst with 9 wt% SiO2 coating showed both high CO2 conversion (63%) and high selectivity toward C2+ hydrocarbons (74%), while further higher coating led to suppression of catalyst activity. The analytical characterization of SiO2-coated catalysts confirmed the interactions of SiO2–Fe and SiO2–Al2O3, which largely reduced the metal–support interaction and decreased the reduction temperature of iron oxide. In addition, an increase of adsorption capacity for CO was observed with desired SiO2 coating. It is likely that SiO2-coating improved the catalyst hydrophobic property, thereby reducing the negative impact of water by-product and facilitating the reverse water gas shift reaction and subsequent hydrogenation towards higher CO2 conversion to higher hydrocarbons.