(173e) Scale-up of Electrochemical Carbon Dioxide Separation Using Membrane Electrode Assemblies

Scale-up of multi-cell membrane electrode assembly (MEA) systems require reproducible fabrication of reliable electrodes and membrane materials. Optimization of electrode support and catalyst microstructures ensures a high rate of CO₂ separation through the anion exchange membrane. Separation of CO₂ from a 5–7 mol% CO₂, high-humidity gas mixture, representative of an exhaled breath, was demonstrated by a sub-scale system. Screen-printed Pt and IrO₂ electrodes were fabricated and evaluated as single MEAs to measure baseline CO₂ removal rates and electrochemical behavior. Catalyst microstructures were characterized using scanning electron microscope (SEM) imaging. Electrode mass and charge transfer resistances were quantified using electrochemical impedance spectroscopy (EIS). The electrode efficiency and CO₂ flux were measured over a range of equivalent full-scale breathing flow rates (40 L/min–120 L/min) for 3, 7, 11, and 22 cell stacks at variable current densities. The multi-cell system displayed performance linearity and uniformity with increasing number of cells. For a full-scale flow rate of 80 L/min, the multi-cell system achieved a CO₂ flux of 1.57 L/m²Â·min with an electrode efficiency of 75%. Flow field design and cell hydrodynamics were addressed for scale‑up of the electrochemical system.