[China Science Daily] Scientists Achieve Efficient Electrochemical Synthesis of Ethylene

Recently, significant progress has been made in the research on coal-based acetylene-to-ethylene conversion by the team led by Academician Bao Xinhe and Researcher Gao Dunfeng from the Dalian Institute of Chemical Physics, Chinese Academy of Sciences. By regulating mass transfer between catalyst particles, the team enhanced the performance of the electrocatalytic semi-hydrogenation of acetylene, achieving electrochemical ethylene synthesis at ampere-level current densities. The related results have been published in Angewandte Chemie International Edition.

Ethylene is an important basic chemical raw material, currently mainly produced through the steam cracking of petroleum hydrocarbons. Given China's abundant coal resources and scarce oil reserves, coal-based acetylene-to-ethylene production has become an important non-petroleum route in recent years. The acetylene electrochemical semi-hydrogenation to ethylene process driven by renewable energy and using water as the hydrogen source offers advantages such as mild reaction conditions and low carbon emissions. However, issues such as high reaction overpotential and relatively low ethylene production rate and selectivity still exist. Current research mainly focuses on the regulation of catalytic active structures, while mass transfer effects at the mesoscopic scale are often overlooked.

The research team, through quantitative analysis, revealed the critical role of mass transfer between particles in the catalyst layer of gas diffusion electrodes. When the average inter-particle distance of copper cube electrodes increased to 265 nanometers, a Faradaic efficiency of 97.4% for ethylene and an ethylene partial current density of 1.5 amperes per square centimeter were achieved in an alkaline membrane electrode electrolyzer. Electrochemical impedance spectroscopy, operando Raman spectroscopy, and finite element simulation results indicate that increasing the inter-particle distance of copper cubes effectively promotes the mass transfer of acetylene and ethylene between particles, accelerating the acetylene adsorption and ethylene desorption processes, thereby achieving efficient electrosynthesis of ethylene.