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 Co-0 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 Co-0 species crystallinity and the formation of Co-2 SiO4 and/or CosbndOsbndSi species which are unfavorable to the form Co-0 species. The RT400 catalyst exhibits the highest Co-0 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 degrees C, the CO2 reaction rate (CO2 conversion) of the RT400 catalyst can reach 2.98 x 10(-5) mol/g(cat)/s (40%), the CH4 and CO selectivity are 86.7% and 13.3%, respectively.