Photocatalytic Semi-Hydrogenation of Acetylene to Ethylene in Water Powered by a Copper-functionalized Hydrogen-Bonded Organic Framework

Abstract

Light-driven approaches for the selective semi-hydrogenation of acetylene to ethylene are emerging as sustainable alternatives to conventional thermochemical purification methods. The realization of a highly selective, robust, and recyclable photocatalyst that avoids noble metals, operates under visible light, and uses water as the proton source remains a major challenge. Here, we report the first demonstration of a supramolecular crystalline material as photocatalyst for the visible-light powered conversion of acetylene to ethylene. The catalyst is a copper-loaded hydrogen-bonded organic framework 1,3,6,8-tetrakis(p-benzoic acid) pyrene (Cu@HOF), which integrates light-harvesting and catalytic function within a single material and uses water as the proton source. Under a pure acetylene atmosphere, Cu@HOF achieves an overall ethylene production of 3.01 mol per gram of Cu with ≥99.9% selectivity after 16 h of irradiation. Under the industrially relevant conditions with a mixed acetylene/ethylene atmosphere, Cu@HOF enables near 100% acetylene conversion within only 75 minutes and without over-hydrogenation of ethane. The heterogeneous nature of the catalyst allows straightforward recovery and reusability, retaining catalytic activity under industrial mixture conditions over at least four consecutive cycles.