Fully Exposed Nickel Clusters for Semihydrogenation of Acetylene

Abstract

Semihydrogenation of acetylene to ethylene is a key process for ethylene purification in the chemical industry. The pursuit of an effective non-noble metal acetylene selective hydrogenation catalyst with low cost, high efficiency, and ultrastability is extremely urgent, especially for industrial applications. However, achieving high ethylene selectivity at full conversion under a low reaction temperature remains challenging due to the imbalance of the H2 splitting ability and intermediate (ethylene) hydrogenation. Herein, we designed atomically dispersed and fully exposed Ni clusters on a nanodiamond@graphene support. H2–D2 exchange experiments and density functional theory calculations reveal that acetylene and hydrogen can be efficiently activated on fully exposed Ni cluster sites due to the enhanced catalytic hydrogenation catalytic ability. Furthermore, the desorption of ethylene on fully exposed Ni cluster sites is much more favored compared to further dissociation of H2, leading to the high selectivity of ethylene. Thereby, the fully exposed Ni cluster catalyst delivered an ethylene selectivity of 85% at full conversion for semihydrogenation of acetylene at 190 °C with a specific activity of 667 mLC2H2·gNi–1·min–1, exceeding the catalytic efficiency of most supported Ni catalysts. The implementation of the fully exposed Ni cluster catalyst provides an effective strategy for improving the catalytic efficiency of non-noble metal acetylene selective hydrogenation catalysts while obtaining high ethylene selectivity. The precise regulation of metal active sites at the subnanometer scale has a significant effect on the rational design of high catalytic performance atomically dispersed non-noble metal catalysts.