Promoting Effects of Zr on CO2 Hydrogenation over Porous Co/CexZr1-xO2-δ Catalyst.

The porous Co/CexZr1-xO2-δ catalysts were prepared by using a template agent-impregnation method. The physicochemical properties of the prepared catalysts were studied by using the XRD, BET, H2-TPR, and H2-TPD. The effects of the catalyst structure and Zr dosage on CO2 hydrogenation performances were also investigated. The porous CexZr1-xO2 support prepared by the hard-template method has a large specific surface area and developed pore structure. With the increment of Zr dosage, the crystal phase structure of the prepared porous CexZr1-xO2 support transforms from cubic phase to tetragonal phase. The Co-Ce-O-Zr solid solution was formed in the corresponding catalyst by introducing an appropriate amount of Zr and significantly improved the reducibility of the Co3O4/CexZr1-xO2 precursors, by which the interaction between the active Co0 and support was enhanced. At the same time, it is conducive to the formation of oxygen vacancies and highly dispersed Co0 to promote the hydrogenation active sites to be formed in the corresponding catalyst, and thus promoting the CO2 hydrogenation. The porous CoCe0.99Zr0.01 catalyst with the Zr content of 1.0 mol% has the best catalytic performances. At 400 °C and atmospheric pressure, the CO2 hydrogenation conversion and CH4 selectivity on the CoCe0.99Zr0.01 catalyst reached 59.8% and 94.7%, respectively.