Enhancing selectivity for semi-hydrogenation of Ni by periodic isolation in the MM′X structure

Abstract

Semi-hydrogenation of acetylene is of great importance but presents a significant challenge in maintaining high ethylene selectivity for complete conversion of acetylene. Herein, we report that the over-hydrogenation on Ni could be suppressed by forming NiMnGe, a typical MM′X (M, M′ – transition metals and X – p-block element) intermetallic compound. A high ethylene selectivity (91.8–98.4%) for the complete conversion of acetylene is achieved over a wide temperature window. Further hydrogenation of ethylene is ceased on the intermetallic catalysts by easy desorption of ethylene and a high energy barrier for further reaction, ensured by Ni isolation in the MM′X lattice. The unique electronic structure induced by the substitution of Mn with Fe decreases the coverage of acetylene on the surface, thereby significantly suppressing the polymerization of acetylene. Our work highlights the potential of using intermetallic compounds as a platform to design heterogeneous catalysts.