The production of polymers from ethylene requires the ethylene feed to be sufficiently purified of acetylene contaminant. Accomplishing this task by thermally hydrogenating acetylene requires a high temperature, an external feed of H₂ gas and noble-metal catalysts. It is not only expensive and energy-intensive, but also prone to overhydrogenating to ethane. Here we report a photocatalytic system that reduces acetylene to ethylene with ≥99% selectivity under both non-competitive (no ethylene co-feed) and competitive (ethylene co-feed) conditions, and near 100% conversion under the latter industrially relevant conditions. Our system uses a molecular catalyst based on earth-abundant cobalt operating under ambient conditions and sensitized by either [Ru(bpy)₃]²⁺ or an inexpensive organic semiconductor (metal-free mesoporous graphitic carbon nitride) under visible light. These features and the use of water as a proton source offer advantages over current hydrogenation technologies with respect to selectivity and sustainability.

由乙烯生产聚合物需要乙烯进料充分纯化乙炔污染物。通过热加氢乙炔完成这一任务需要高温、H ₂气体的外部进料和贵金属催化剂。它不仅昂贵且耗能，而且容易过度氢化成乙烷。在这里，我们报告了一种光催化系统，该系统在非竞争（无乙烯共进料）和竞争（乙烯共进料）条件下以≥99% 的选择性将乙炔还原为乙烯，并且在后者的工业相关条件下转化率接近 100%。我们的系统使用基于地球丰富的钴的分子催化剂，在环境条件下运行并被 [Ru(bpy) ₃ ] ^2+敏化或在可见光下廉价的有机半导体（无金属介孔石墨氮化碳）。这些特征和使用水作为质子源在选择性和可持续性方面提供了优于当前氢化技术的优势。