Modeling and Comparative Analysis of CO2 Absorption Columns in Electrochemical and Thermochemical Carbon Capture Systems

Abstract

Deployment of post-combustion carbon dioxide (CO₂) capture technologies is needed to reduce emissions from power and industrial sources. Comparisons between existing thermochemical CO₂ capture methods and emerging electrochemical concepts can help contextualize the promise of these new approaches. Here, we investigate the required absorber sizes for three capture systems: amine scrubbing using monoethanolamine (MEA), direct electrochemical (redox-active sorbent), and indirect electrochemical (pH swing). For the electrochemical systems, we study how column size varies as a function of molecular properties and operating conditions, finding that parameters most closely related to CO₂ uptake rates (i.e., rate constants and pK_a) have the greatest impact. Through a Monte Carlo analysis, we find that the direct process can be designed to have column sizes similar to the thermochemical process; however, the CO₂ uptake rate in the indirect process is too slow to enable smaller columns. Broadly, this work connects system input parameters to absorber performance for electrochemical CO₂ capture and provides a foundation for techno-economic and engineering analyses.