(600d) Electrochemical CO2 Utilization: Scalable System Operation for Formic Acid Production

In recent years, research into the electrochemical reduction of CO₂ has grown exponentially. Formic acid (FA) has become a particular value product from CO₂ due to its versatility [1], optimal atom economy [2], and thermodynamic favorability [3]. FA can be produced electrochemically via a direct two-electron transfer process involving CO₂ with a proton source, requiring less energy input and fewer reaction steps than the conventional Kemira process. However, product selectivity, electrode stability, and low Faradaic efficiency due to increased resistance under constant current, remain key issues for CO₂ reduction to FA [3].

University of Kentucky’s Center for Applied Energy Research (UK CAER) is currently investigating reactor designs to address the challenges associated with electrochemical CO₂ conversion to FA [4]. The current reactor system employs: (1) an organic-based charge carrier which shuttles charge directly to the catalyst to enable CO₂ reduction to FA; (2) novel electrode materials to mitigate large voltages and improve conductivity; and (3) a flow system which not only allows for the volumetric scale-up of both charge carrier and catalyst, but also decouples the charger carrier re-energized and FA production processes to protect the catalyst’s stability due to overpotential. Through careful adjustment of electrode, charge carrier, and electrolyte selection, cell resistances have decreased by over 15%, facilitating conduction necessary for effective CO₂ reduction to FA. The system uses a highly specific engineered catalyst, which has produced over 100 mM FA at a rate of over 10 mM FA/hour following the aforementioned electrode/charge carrier changes. System design considerations (flow rate, bulk volume) and modeling of the system will also be discussed.

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2. Spurgeon JM, Kumar B. A comparative technoeconomic analysis of pathways for commercial electrochemical CO 2 reduction to liquid products. Energy & Environmental Science. 2018;11(6):1536-51.
3. Pérez-Fortes M, Schöneberger JC, Boulamanti A, Harrison G, Tzimas E. Formic acid synthesis using CO2 as raw material: Techno-economic and environmental evaluation and market potential. international journal of hydrogen energy. 2016 Oct 5;41(37):16444-62.
4. Omosebi, A., Landon, J., Thompson, J., and Liu, K. “Process Intensification for Electrochemical Utilization of CO2.” Proceedings of AIChE 2019 Annual Meeting. 11 Nov 2019.