Ethylene Production from Carbonate Using a Bipolar Membrane Electrolysis System

Abstract

High Resolution Image Download MS PowerPoint Slide Electrochemical CO 2 reduction has attracted significant interest as a pathway for achieving a carbon-neutral society. However, conventional gas-phase CO 2 electrolysis cell configurations often face challenges like low CO 2 utilization efficiency due to carbonate crossover, and costly integration with carbon capture systems. The membrane electrode assembly (MEA) electrolysis cell configuration involving a bipolar membrane (BPM) has been recently spotlighted as this system can directly release CO 2 stored in carbonate solutions using a pH swing process driven by water dissociation within the BPM. Here, we assess the reactor’s capacity to liberate CO 2 and facilitate its conversion into ethylene (C 2 H 4 ), using Cu–Ag catalysts and carbon capture solutions such as potassium carbonate (K 2 CO 3 ). Bench-top flow cell system testing using an optimized Cu–Ag electrocatalyst demonstrates that the conversion of CO 2 to C 2 H 4 reaches 10% Faradaic efficiency, corresponding to a partial current density of 10 mA/cm 2 . During all tests, the BPM-MEA electrolysis cell also maintained approximately 0% CO 2 concentration in the outlet over 24 h. Operating at elevated temperatures, such as 50 °C, has shown promising results in our exploration, demonstrating improved C 2 H 4 Faradaic efficiency and current densities. Lastly, we examine the feasibility of this combined CO 2 generation and conversion reactor architecture and estimate the potential energy and process efficiencies achievable using the BPM-MEA system. While the BPM-MEA system offers innovative solutions for carbon capture and conversion, continued research and optimization are imperative to fully harness its potential for a sustainable future.

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