Electrochemical membrane reactors for the utilisation of carbon dioxide

Abstract

Climate change is among the greatest challenges for humankind in the 21st century. Carbon Capture and Utilisation (CCU) allows the production of value-added chemicals from CO2, reducing at the same time the undesirable effects of global warming. Among the available methods for CO2 utilisation, the electrochemical reduction appears as a promising technological solution to store intermittent renewable energy in the form of chemical bonds, leading to valuable chemicals such as formic acid, methanol or methane, which can be put back into the market. The application of electrochemical membrane reactors (ecMRs) for the valorisation of CO2 allows the separation of the catholyte and anolyte compartments, leading to an enhanced separation of reaction products and avoiding their re-oxidation. Among these membrane-based reactors, the utilisation of Membrane Electrode Assemblies (MEAs), where the cathode and anode are coupled with a conductive membrane, are gaining importance. Besides, gas diffusion electrodes (GDEs) are able to reduce mass transfer limitations and therefore, enhance efficiencies in the process of CO2 electroreduction. Thus, the aim of the present review is to compile the literature on the application of membrane reactors for CO2 electroreduction, paying special attention to the type of membrane, reactor configuration and catalytic material in electrochemical reactors. Then, a performance comparison in terms of Faradaic efficiency for different products reported to date, is carried out.