Investigation of CO₂ Reduction to Formate in an Industrial-Scale Electrochemical Cell through Transient Numerical Modeling

Gas diffusion electrodes (GDEs) are promising for scaling up industrial CO2 electrochemical reduction cells. This study introduces a transient numerical model representing an industrial electrolyzer. The model incorporates electrochemical kinetics, homogeneous reaction kinetics, and transport phenomena within the cathode compartment. By integrating a global mass balance over the entire electrolyte, it analyzes time-dependent performance variations such as Faradaic efficiency (FE). This allows us to simulate formate production and understand mass transport limitations within the GDE. Our results demonstrated a 4% increase in FE when the electrolyte flow rate was increased from 120 to 360 mL/min. However, further increasing the flow rate to 830 mL/min showed diminishing returns. Additionally, increasing the KOH concentration in the catholyte from 0.5 to 1 M resulted in a 7–10% increase in FE. A slight further increase was observed when increasing from 3 to 4 M. This analysis provides valuable insights into optimizing electrochemical reduction processes at an industrial scale.