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

Identifier:  imarina:9465603

Handle: https://hdl.handle.net/20.500.11797/imarina9465603

Authors:  Rodriguez-Reartes, SB; Llovell, F

Abstract:
Efforts to reduce atmospheric CO2 levels focus on minimizing fossil fuel consumption, integrating renewable energy systems, and implementing CO2 capture, storage, and utilization. While carbon removal from atmosphere technologies shows promising, industrial efforts prioritize point-source capture for sustainability. A key challenge in solvent design is screening candidates and defining selection criteria. Robust models are needed to characterize their thermophysical behavior for CO2 capture. This study adopts a multiscale approach to investigate the CO2 gas absorption in phosphonium-based ionic liquids (ILs) with eight anions. The trihexyltetradecylphosphonium cation [P666,14]+ was paired with various anions due to their known CO2 absorption capacity. New molecular models are developed using the soft-SAFT equation, leveraging existing coarse-grain models, analyzing molecule charge distribution through Turbomole-COSMO software for new ILs, and approximating association parameters via density functional theory calculations. Once the models are validated against experimental data, soft-SAFT is used predictively to evaluate the thermophysical properties of these ILs in a wide range of conditions. The analysis encompasses estimations of key process indicators, including the cyclic working capacity, enthalpy of desorption, and CO2 diffusion coefficient, ultimately proposing the [P666,14][Ac] and [P666,14][bis(2,4,4-TMPP)] ILs as the most promising solvents. This study validates soft-SAFT as a reliable screening tool for CO2 capture solvents and process modeling.