CO2 hydrogenation to methane over Co/KIT-6 catalysts: Effect of Co content.

The ordered mesoporous Co/KIT-6 catalysts with different Co loading (15–30 wt%) were prepared by impregnation method for CO 2 hydrogenation. The physicochemical properties of the catalysts were characterized by H 2 -TPR, XRD, BET, H 2 -TPD, and CO 2 -TPD. The results show that the crystal size of Co species increases with the increasing Co content and the dispersion of Co species reveals an opposite trend. The adsorption capacities of H 2 and/or CO 2 molecules achieve a maximum value at the Co loading of 25 wt%. The CO 2 reaction rate and CH 4 selectivity are in the following order: Co15 < Co20 < Co30 < Co25. With the increasing of Co loading, the CO 2 reaction rate increases from 2.21 × 10 −5  mol/g cat /s (CO 2 conversion of 29.8%) for the Co15 catalyst to 3.91 × 10 −5  mol/g cat /s (CO 2 conversion of 52.6%) for the Co25 catalyst, and the CH 4 selectivity improves from 67.0% for the Co15 catalyst to 94.5% for the Co25 catalyst at 360 °C, while the other product is CO. The catalytic performance and products distribution of the Co/KIT-6 catalysts for CO 2 hydrogenation are sensitive to the crystal size of Co species which can be adjusted by changing the Co content in Co/KIT-6 catalysts. [ABSTRACT FROM AUTHOR]