Multi-Physics Modeling of Electrochemical Conversion of Carbon Dioxide to Formic Acid

Electrochemical conversion of CO₂, a common greenhouse gas to formic acid, methanol, ethylene, and syngas is being increasingly pursued as a means for CO₂ recycle to value added products employing renewable energy and also for energy storage.  The authors have been actively involved in advancement of the technology for selective conversion of CO₂ to formic acid. Special emphasis of this research is on process modifications for techno-economic feasibility which is imperative for future commercialization. Hence, multi-scale modeling is pursued to aid the experimental design. The reactor design, the catalyst and electrode structure for efficient, scale up of this process requires a comprehensive formulation of the multi-scale and multi-physics process phenomena, including aqueous transportation, membrane transportation, multiphase flow, dispersion, ion migration and surface reactions. This work presents a modeling and numerical simulation approach for understanding the CO₂ conversion process to formic acid and model validation. A phenomenological process model of the CO₂ conversion process is developed to simulate the process behavior under steady state and transient operating conditions, allowing to study the complex system phenomena and estimate scale-up performance. An approach for calibrating the model input data for such systems from the experimental data is illustrated. This type of calibrating approach could also be applicable to other similar electrochemical systems.