Near 100% Conversion of Acetylene to High-purity Ethylene at Ampere-Level Current.

Abstract

Direct production of high-purity ethylene from acetylene using renewable energy through electrocatalytic semi-hydrogenation presents a promising alternative to traditional thermocatalytic processes. However, the low conversion of acetylene results in a significant amount of acetylene impurities in the product, necessitating additional purification steps. Herein, a tandem electrocatalytic system that integrates acetylene electrolyzer and zinc-acetylene battery units for high-purity ethylene production is designed. The ultrathin CuO nanoribbons with enriched oxygen vacancies (CuO_1-x NRs) as electrocatalysts achieve a remarkable 93.2% Faradaic efficiency of ethylene at an ampere-level current density of 1.0 A cm^-2 in an acetylene electrolyzer, and the power density reaches 3.8 mW cm^-2 in a zinc-acetylene battery under acetylene stream. Moreover, the tandem electrocatalysis system delivers a single-pass acetylene conversion of 99.998% and ethylene selectivity of 96.1% at a high current of 1.4 A. Experimental data and calculations demonstrate that the presence of oxygen vacancies accelerates water dissociation to produce active hydrogen atoms while preventing the over-hydrogenation of ethylene. Furthermore, techno-economic analysis reveals that the tandem system can dramatically reduce the overall ethylene production cost compared to the conventional thermocatalytic processes. A novel strategy for complete acetylene-to-ethylene conversion under mild conditions, establishing a non-petroleum route for the production of ethylene is reported.