Design methodology for mass transfer-enhanced large-scale electrochemical reactor for CO₂ reduction

The electrochemical conversion of CO₂ using a continuous flow membrane reactor is a promising technology. This is because the membrane reactor can achieve high productivity and selectivity by enhancing the mass transfer of CO₂. In an industrial-scale reactor, the extrinsic properties that facilitate the mass transfer rate are crucial because the uniform flow distribution and high production rate can only be achieved when the interface and flow patterns are properly designed. Herein, we experimentally measured the production rate of CO in a large-scale electrochemical CO₂ reduction reactor by varying the pH, interface, and flow pattern. The result indicated that optimization of the flow pattern alone can improve the production rate of CO by 28% indicating that a high convection rate through gas diffusion electrode (GDE) results in a high production rate. A three-dimensional computational fluid dynamic model was developed to quantify the effect of the new flow pattern on the mass transfer. From the model, the Peclet number increased by 28%, which is consistent with the CO partial current increment. This result indicates that the convective mass transfer improves the production rate. Additionally, we proposed a general guideline for the flow pattern design for a large-scale electrochemical CO₂ reduction reactor that maximizes convective mass transfer through a GDE.