(240f) Design and Scale-up of a Distillation-Inspired Electrochemical CO2 Reduction Reactor

Electrochemical cell design is a crucial step in scaling up effective CO₂ reduction systems for decarbonization. Current CO₂ electrolyzer designs exhibit limitations when scaled up to larger electrode areas due to poor energy efficiency and reduced mass transport of gaseous reactant feed and product separation due to pressure drops.

To address these challenges, we present the e-CO₂LUMN: a novel, high-pressure CO₂ electrolyzer column that emulates distillation column principles for efficient single-pass conversion of CO₂ to ethanol. Operating up to 40 bars, with an electrode active area of 20,000 cm², a power rating of 7.2 kW and a 20-stage configuration, the e-CO₂LUMN enables enhanced transport of reactants though a vertical counter-current gas-liquid flow via a sparger-based gas distribution.

For achieving high ethanol yields, the overall reaction is split into a three-step sequential reaction of CO₂ to CO, CO to Acetaldehyde and Acetaldehyde to Ethanol, for fine-tuning the selectivity and to leverage reduced energy barriers. The design was engineered using ASME Boiler and Pressure Vessel Codes (BPVC), with mechanical calculations for key vessel components for operation under high pressure and was evaluated for safety against failure conditions.

This work details the design fundamentals required to scale a single stage in the e-CO₂LUMN from electrodes of 50 cm² electrode areas to 1,000 cm² operating at pressures of up to 40 bar and current densities of 200 mA/cm². Increased operating pressure enhances the solubility of CO₂ in the aqueous electrolyte, resulting in higher yields of CO₂ electrochemical reduction products. The results demonstrate the importance of electrochemical performance and compliant engineering design in advancing scalable and efficient production of fuels and chemicals from waste CO₂ feedstocks.