Recently, the research group led by Prof. DENG Dehui from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Scientists (CAS) reported a direct electrocatalytic process for highly selective ethylene production from CO reduction with water over Cu catalysts at room temperature and ambient pressure. This work was published in Angew. Chem. Int. Ed.

Performance of CO electroreduction over Cu-Ps loaded on hydrophobic carbon papers and schematic illustration for CORTE process on Cu catalysts with the assistant of the hydrophobic micro-porous layer to improve the CO diffusion. (Image by CHEN Ruixue and GAO Hehua)

Ethylene (C₂H₄) is an important building block for chemical industry and usually produced by steam cracking of naphtha feedstocks at 800-900 ^oC. However, considering the utilization of the nonpetroleum carbon resources, converting CO from syngas (CO + H₂) to C₂H₄ is also regarded as one of the key processes.

Fischer-Tropsch synthesis (FTS) is usually conducted under high temperature (200-450 ^oC) and high pressure (5-50 bar). The products from FTS process are often limited by the Anderson-Schulz-Flory distribution, which leads to 30% selectivity of C₂ hydrocarbons at most.

Through rational optimization of polytetrafluoroethylene content to increase CO concentration at the surface of electrode and Cu particle catalysts to enhance the C-C bond coupling, the researchers realized highly selective production of ethylene process from electrocatalytic CO reduction with water at room temperature and ambient pressure.

This electrocatalytic CORTE process could achieve an unprecedentedly high ethylene FE of 52.7%. Moreover, the selectivity based on CO conversion to ethylene was around 70%, exceeding the 30% selectivity limitation from CO to C₂ hydrocarbons in traditional FTS process, which always delivers uncontrollable mixture of C₁-C₄ hydrocarbons and massive CO₂.

The researchers studied the reaction active sites and mechanism by DFT calculations and found that Cu(100) was the most preferred plane for C₂H₄ formation via considering all possible products.

"This electrocatalytic CORTE process provides a highly selective, energy-efficient and eco-friendly way to convert the abundantly industrial CO to C₂H₄ in comparison with the Fischer-Tropsch synthesis process," said Prof. DENG.

The study was supported by the Ministry of Science and Technology of China, the National Natural Science Foundation of China, Key Research Program of Frontier Sciences of the Chinese Academy of Sciences, the DNL Cooperation Fund and National Postdoctoral Program for Innovative Talents, and Collaborative Innovation Center of Chemistry for Energy Materials (2011. iChEM).