Thermal modulation of reaction equilibria controls mass transfer in CO2-binding organic liquids

CO2-Binding organic liquids (CO2BOLs) are non-aqueous solvents which may reduce the parasitic energy of carbon capture processes. These solvents exhibit surprising mass transfer behavior: at fixed pressure driving force, the flux of CO2 into CO2BOLs decreases exponentially with increased temperature...

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Bibliographic Details
Published in:Energy & environmental science 2023-02, Vol.16 (2), p.484-490
Main Authors: Moore, Thomas, Varni, Anthony J, Pang, Simon H, Akhade, Sneha A, Li, Sichi, Nguyen, Du T, Stolaroff, Joshuah K
Format: Article
Language:English
Subjects:
Amines
Binding
Carbon dioxide
Carbon sequestration
Chemical reactions
Density functional theory
First principles
Fluctuations
Hexanol
Mass transfer
Organic liquids
Solvents
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Summary:CO2-Binding organic liquids (CO2BOLs) are non-aqueous solvents which may reduce the parasitic energy of carbon capture processes. These solvents exhibit surprising mass transfer behavior: at fixed pressure driving force, the flux of CO2 into CO2BOLs decreases exponentially with increased temperature, a phenomenon not observed in aqueous amines. Here, we demonstrate that this phenomenon is primarily driven by a shift in reaction equilibrium, which reduces the degree to which chemical reactions enhance the CO2 flux. First-principles surface renewal models quantitatively reproduce mass transfer data for CO2 absorption into 2-EEMPA, IPADM-2-BOL and DBU:Hexanol across a range of temperatures. Density functional theory calculations are used to identify structural modifications likely to improve the CO2 flux. These findings reveal a fundamental trade-off between CO2 flux and the energy required for solvent regeneration, and provide a theoretical foundation for rational solvent design and the development of physics-informed mass transfer models.
ISSN:1754-5692
1754-5706
DOI:10.1039/d2ee03237f