Large-scale production of polyethylene in industry requires efficient elimination of the trace amount of acetylene impurity. Currently, zeolite adsorption or the conversion of acetylene to ethylene via selective semi-hydrogenation on Pd catalysts is the commonly used method. In this work, we investigate the reaction mechanisms of acetylene hydrogenation on defective graphene (DG) supported single-atom catalysts (SACs), M₁/SV-G and M₁/DV-G (M=Ni, Pd and Pt) using density functional theory (DFT), where SV-G and DV-G represent DG with single and double vacancies, respectively. It is shown that the metal single-atoms (SAs) as well as their different coordination numbers both affect the activity and selectivity of the hydrogenation process. M₁/DV-G provides better H₂ dissociation ability than M₁/SV-G, which accounts for the poor acetylene hydrogenation activity of M₁/SV-G. Based on the reaction barriers, Pt₁/DV-G and Ni₁/DV-G are better catalysts than other systems considered here, with Ni₁/DV-G exhibiting high selectivity for the semi-hydrogenation product of acetylene. These results provide insights for the design of highly selective and noble-metal-free SACs for acetylene hydrogenation on carbon materials.

工业上聚乙烯的大规模生产需要有效消除痕量的乙炔杂质。当前，在Pd催化剂上沸石吸附或通过选择性半氢化将乙炔转化成乙烯是常用的方法。在这项工作中，我们使用以下方法研究乙炔在有缺陷的石墨烯（DG）负载的单原子催化剂（SAC），M ₁ / SV-G和M ₁ / DV-G（M = Ni，Pd和Pt）上的反应机理。密度泛函理论（DFT），其中SV-G和DV-G分别表示具有单空位和双空位的DG。结果表明，金属单原子（SAs）及其不同的配位数均会影响氢化过程的活性和选择性。中号₁/ DV-G比M ₁ / SV -G提供更好的H ₂解离能力，这说明了M ₁ / SV-G的乙炔氢化活性差。基于反应障碍，Pt ₁ / DV-G和Ni ₁ / DV-G是比此处考虑的其他体系更好的催化剂，其中Ni ₁ / DV-G对乙炔的半加氢产物表现出高选择性。这些结果为设计用于碳材料上的乙炔加氢的高选择性，不含贵金属的SAC提供了见识。