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

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 & PRIME;X (M, M & PRIME; - 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 & PRIME;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.

Automated summary

In this study, the formation of NiMnGe, a typical intermetallic compound of MM & PRIME;X (M, M & PRIME; - transition metals and X - p-block element), was found to suppress over-hydrogenation on Ni, leading to high ethylene selectivity for complete conversion of acetylene. The intermetallic catalysts showed a wide temperature range for complete conversion with high ethylene selectivity (91.8-98.4%), due to the easy desorption of ethylene and a high energy barrier for further reaction. The substitution of Mn with Fe in the MM & PRIME;X lattice resulted in a unique electronic structure that decreased the coverage of acetylene on the surface, preventing its polymerization. This work highlights the potential of using intermetallic compounds as a platform for designing heterogeneous catalysts.