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

27 October 2021, Version 1
This content is a preprint and has not undergone peer review at the time of posting.

Abstract

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 tradeoff between these efficiency metrics, and propose a new metric, the combined efficiency, that can be used to further explore this tradeoff 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.

Keywords

Electrochemical
Carbon capture
Redox-active capture molecule
Thermodynamics

Supplementary materials

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Title
Thermodynamic Modeling of CO2 Separation Systems with Soluble, Redox-Active Capture Species
Description
Supporting Information (SI) for the main text. The SI discusses the derivation and application of governing equations and provides thermodynamic modeling results for various scenarios.
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