Thermodynamic Modeling of CO2 Separation Systems with Soluble, Redox-Active Capture Species

• Published in: Industrial & engineering chemistry research Vol. 61; no. 29; pp. 10531 - 10546
• Main Authors: Clarke, Lauren E., Leonard, McLain E., Hatton, T. Alan, Brushett, Fikile R.
• Format: Journal Article
• Language: English
• Published: American Chemical Society 27.07.2022
• Subjects: Separations
• ISSN: 0888-5885; 1520-5045
• DOI: 10.1021/acs.iecr.1c04185

Electrochemical approaches hold promise for energy-efficient and modular carbon dioxide (CO2) separation systems that can make direct use of renewably generated electricity. Here, we employ a thermodynamic modeling approach to estimate the upper performance bounds of CO2 separation processes that use soluble, redox-active capture species. We contemplate the impact of tunable molecular and electrolyte properties on the thermodynamic and faradaic efficiencies of four characteristic system configurations. We find a trade-off between these efficiency metrics and propose a new metric, the combined efficiency, that can be used to further explore this trade-off and identify desirable property sets that balance energy and materials requirements. Subsequently, we determine effective CO2 binding affinities of redox-active capture molecules and demonstrate how these values are dependent upon molecular properties, system format, and operating conditions. Overall, this analytical framework can help guide molecular discovery and electrolyte engineering in this emerging field by providing insight into target material properties.