CO2 hydrogenation to methane over mesoporous Co/SiO2 catalysts: Effect of structure

The mesoporous Co/SiO2 catalysts with 10 wt.% Co loading were prepared by grind-impregnation method for CO2 hydrogenation, and the mesoporous SiO2 materials with different structures were used as the supports. The physicochemical properties of the Co/SiO2 catalysts were characterized by TEM, BET, H2-TPR, XRD, and CO2-TPD. The results indicate that the pore size, specific surface area, and the Co° species crystallinity of the Co/SiO2 catalyst increase with increasing crystallization temperature of preparing SiO2 support. The Co/SiO2 catalyst has the best CO2 adsorption property when SiO2 support is prepared at the crystallization temperature of 100 °C. The CO2 reaction rate (CO2 conversion) of the Co/SiO2 catalysts is as follows: CK100 > CK080 > CK120 > CK060 > CK140 > CK040, and the CH4 selectivity follows the order: CK100 > CK080 > CK120 > CK140 > CK060 > CK040, accompanied by a certain amount of by-product CO molecules. At 360 °C, the CO2 reaction rate (CO2 conversion) of the CK100 catalyst is up to 3.29 × 10−5 mol/gcat/s (44.3%), the CH4 and CO selectivity are 86.5% and 13.5%, respectively.