Unsupported Ni-Co alloy as efficient catalysts for CO2 methanation

Abstract

The development of efficient catalysts for the hydrogenation of abundant but inert CO 2 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 (Ni 1 Co 2 -C and Ni 3 Co 2 -C) comprised Ni-Co alloy, derived from spinel Ni x Co y O, while the Ni 1 -Co 2 -M catalyst (Ni and Co mixture, physical mixing ahead of H 2 reduction) didn’t contain it. The subsequent activity evaluation for CO 2 hydrogenation uncovered a profound synergistic effect between Ni and Co in Ni-Co alloy from composite catalysts, which played a significantly effect on their CO 2 hydrogenation activity, CH 4 selectivity, and stability. • The formation of spinel Ni x Co y O is readily reduced by H 2 to afford Ni-Co alloy. • Synergistic effect between Ni and Co in Ni-Co composite catalysts is disclosed. • The Ni-Co alloy accounts for the high performance of Ni-Co composite catalysts. • Ni-Co composite catalysts represents a potential catalyst for CO 2 methanation.