Characterizing the Potential of Phosphonium-Based Ionic Liquids for CO₂ Capture via Multiscale Modeling

Area of Science:

• Chemical Engineering
• Materials Science
• Computational Chemistry

Background:

• Reducing atmospheric CO₂ is critical, with point-source capture prioritized for industrial sustainability.
• Screening and selecting effective CO₂ capture solvents requires robust thermophysical characterization models.
• Ionic liquids (ILs) show potential for CO₂ absorption, but efficient solvent design is challenging.

Purpose of the Study:

• To develop and validate multiscale molecular models for predicting CO₂ absorption in phosphonium-based ionic liquids.
• To screen various phosphonium-based ILs for their suitability as CO₂ capture solvents.
• To identify key thermophysical properties influencing CO₂ capture performance.

Main Methods:

• A multiscale approach combining soft-SAFT equation, coarse-grain models, and density functional theory calculations.
• Development of new molecular models for ILs, including charge distribution analysis using Turbomole-COSMO.
• Validation of models against experimental data and predictive evaluation of IL thermophysical properties.

Main Results:

• Successfully developed and validated soft-SAFT models for phosphonium-based ILs.
• Predicted key process indicators like cyclic working capacity, enthalpy of desorption, and CO₂ diffusion coefficient.
• Identified [P_666,14]-[Ac] and [P_666,14]-[bis-(2,4,4-TMPP)] ILs as highly promising solvents for CO₂ capture.

Conclusions:

• Soft-SAFT is a reliable tool for screening CO₂ capture solvents and process modeling.
• The developed models provide a pathway for efficient design of next-generation CO₂ capture materials.
• This research contributes to advancing sustainable carbon capture technologies.