Ethylene oxide (EO) is a highly versatile chemical intermediate widely used in the production of polymers, solvents, and other industrial chemicals. Currently, EO is produced industrially via the epoxidation of ethylene with oxygen over silver-based catalysts at 230–270 °C and 1–3 MPa. However, this process suffers from limited ethylene conversion and EO selectivity, as well as substantial energy consumption and CO2 emission.
Electrocatalytic ethylene epoxidation driven by renewable electricity, using water as the sole oxidant, offers a green and low-carbon alternative. However, the efficiency of this reaction is limited by the trade-off between ethylene conversion and EO selectivity.
In a study published inJournal of the American Chemical Society, a research team led by Profs. BAO Xinhe and GAO Dunfeng from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences (CAS), in collaboration with Prof. WANG Guoxiong from Fudan University, has developed an efficient strategy for direct electrocatalytic ethylene epoxidation. By stabilizing superoxo species with platinum (Pt) single atoms, the team enhanced EO production.
Single atom Pt-stabilized superoxo species for direct electrocatalytic ethylene epoxidation (Image by WANG Hanyu)
Researchers designed a catalyst comprising Pt single atoms supported on PdO, which facilitates the formation of superoxo species as reactive oxygen species (ROS) and accelerates the selective oxidation of ethylene. This catalyst enables efficient EO production in a zero-gap anion exchange membrane-based membrane electrode assembly (MEA) electrolyzer, achieving a Faradaic efficiency of 74% and a partial current density of 71 mA cm–2.
In addition, a scale-up demonstration using a 100-cm2 electrolyzer achieves an EO production rate of 6.4 g h–1 at a total current of 15 A, highlighting the practical potential of this catalyst design for electrochemical ethylene valorization.
Furthermore, researchers revealed that Pt single atoms, in synergy with perchlorate anion in the electrolyte, promote the formation of abundant superoxo species and accelerate the epoxidation of ethylene activated on the PdO support.
“Our study underscores the importance of generating and stabilizing specific ROS for selective oxidation of organic molecules,” said Prof. GAO.
Article Link：https://pubs.acs.org/doi/10.1021/jacs.6c01386