Unsupported Ni-Co alloy as efficient catalysts for CO2 methanation

The development of efficient catalysts for the hydrogenation of abundant but inert CO2 into valued chemicals has attracted great interests. Although various cheap Ni-Co bimetallic catalysts demonstrating distinguished activity have been explored as alternatives of noble metal catalysts, the real interaction between Ni and Co in Ni-Co catalysts require to be disclosed, further promoting to design more active Ni-Co catalysts. Herein, a couple of unsupported Ni/Co catalysts were prepared by a simple sol-gel method. According to XRD, XPS and HRTEM tests, the Ni-Co composite catalysts (Ni1Co2-C and Ni3Co2-C) comprised Ni-Co alloy, derived from spinel NixCoyO, while the Ni1-Co2-M catalyst (Ni and Co mixture, physical mixing ahead of H2 reduction) didn't contain it. The subsequent activity evaluation for CO2 hydrogenation uncovered a profound synergistic effect between Ni and Co in Ni-Co alloy from composite catalysts, which played a significantly effect on their CO2 hydrogenation activity, CH4 selectivity, and stability.