Hypophosphite-Induced Structural Reconstruction Boosts Cu-Based Catalysts for Semi-Hydrogenation of Acetylene in Excess Ethylene

Selective semi-hydrogenation of acetylene to ethylene in an ethylene-rich stream is critical for polymer-grade ethylene production. Copper catalysts are cost-effective but limited by aggregation of active sites, inadequate hydrogen activation, and side reactions like C–C coupling and over-hydrogenation. We report a sodium hypophosphite-modified cuprous oxide catalyst (Cu 2 O-P) that achieves 100% acetylene conversion with 95% ethylene selectivity at 130 °C (H 2 /C 2 H 2 = 10) and maintains on-stream stability over 130 h. Hypophosphite coordination promotes acetylene adsorption and drives in situ formation of an active copper carbide (CuC x ) phase, boosting hydrogen activation and spillover. Also, it reconstructs bulk copper species into highly dispersed copper NPs (∼5 nm) on a carbon support and further isolates the copper sites at the atomic scale, effectively suppressing C–C coupling and carbon deposition. This surface modification strategy provides a simple method to improve activity, selectivity, and stability simultaneously for metal hydrogenation catalysts with low Tammann temperature.