CO2 hydrogenation to methane over Co/KIT-6 catalyst: Effect of reduction temperature

The mesoporous Co/KIT-6 catalysts with 10 wt% Co loading were prepared at different reduction temperatures. The physicochemical properties of the Co/KIT-6 catalysts were characterized by TEM, BET, XRD, XPS, and CO2-TPD, and the effect of reduction temperature on CO2 hydrogenation catalytic performance of Co/KIT-6 catalysts was studied. The results show that reduction temperature has a significant impact on the specific surface area, crystallinity and content of Co0 species, and CO2 adsorption performance of the prepared Co/KIT-6 catalysts. The low reduction temperature is not conduct to the reduction of CoOx, while the high reduction temperature lead to the increase of Co0 species crystallinity and the formation of Co2SiO4 and/or CosbndOsbndSi species which are unfavorable to the form Co0 species. The RT400 catalyst exhibits the highest Co0 species content and the best CO2 adsorption performance. Both the CO2 hydrogenation catalytic activity and CH4 selectivity of the Co/KIT-6 catalysts follow the order: RT400 > RT350 > RT450 > RT500 > RT550, with a small amount of by-product CO. At the reaction temperature of 340 °C, the CO2 reaction rate (CO2 conversion) of the RT400 catalyst can reach 2.98 × 10−5 mol/gcat/s (40%), the CH4 and CO selectivity are 86.7% and 13.3%, respectively.