Identification of Copper as an Ideal Catalyst for Electrochemical Alkyne Semi-hydrogenation

Selective removal of ∼1% acetylene impurity from ethylene is an essential process to prevent the poisoning of the Ziegler–Natta catalyst in polyethylene production. Developing an earth-abundant catalyst to replace Pd and a new approach to reduce energy consumption represents an immense challenge in this field. Herein, we present an atomic understanding of the trend in electrocatalytic acetylene semi-hydrogenation over 12 transition metals with systematic density functional theory calculations and the computational hydrogen electrode model. Copper stands out and is theoretically identified as the ideal metal for electrocatalytic acetylene conversion to ethylene with a suppressed hydrogen evolution reaction. Our theoretically predicted Cu catalyst has been successfully synthesized and tested to be superior for selective alkyne semi-hydrogenation experimentally, which greatly validates our computational framework for the rational design of the catalyst. This work not only illustrates the key factors determining the activity and selectivity but also provides new suggestions for further optimization of this environmentally benign and economically feasible route for ambient alkyne semi-hydrogenation.