Enhanced low-temperature performance of CO2 methanation over mesoporous Ni/Al2O3-ZrO2 catalysts

Abstract Converting carbon dioxide to value-added chemicals has been attracted much attention, whereas direct hydrogenation of CO 2 to synthetic natural gas (SNG) at a lower temperature remains a big challenge. Mesoporous Al 2 O 3 -ZrO 2 modified Ni catalysts were prepared via a single-step epoxide-driven sol-gel method for CO 2 methanation. Almost 100% selectivity of CH 4 with 77% CO 2 conversion were obtained at a lower temperature of 300 °C, and no catalyst deactivation was observed in 100 h. Different characterization methods including N 2 adsorption-desorption, H 2 -TPR, H 2 -TPD, XRD, XPS, and TEM were combined together to explore the interaction of Ni-ZrO 2 and Al 2 O 3 -ZrO 2 . Incorporation of ZrO 2 into Ni/Al 2 O 3 weakened the Ni-Al 2 O 3 interaction via the combination of Al 2 O 3 -ZrO 2 solid solution, promoting the reduction and dispersion of NiO phase. The adding of higher Zr loading increased the amount of active metallic nickel sites and oxygen vacancies on the composite support, improving obviously the lower temperature catalytic activity and CH 4 selectivity. Higher Ni species loading further resulted in the formation of active Ni sites and improved the low-temperature CO 2 methanation performance. Moreover, the enhanced stability of the Al 2 O 3 -ZrO 2 support and oxygen vacancies provided by the ZrO 2 promoter could help to promote the catalytic stability.