Abstract
Efforts to reduce atmospheric CO(2) levels focus on minimizing fossil fuel consumption, integrating renewable energy systems, and implementing CO(2) 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 CO(2) capture. This study adopts a multiscale approach to investigate the CO(2) gas absorption in phosphonium-based ionic liquids (ILs) with eight anions. The trihexyltetradecylphosphonium cation [P(666,14)](+) was paired with various anions due to their known CO(2) 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 CO(2) diffusion coefficient, ultimately proposing the [P(666,14)]-[Ac] and [P(666,14)]-[bis-(2,4,4-TMPP)] ILs as the most promising solvents. This study validates soft-SAFT as a reliable screening tool for CO(2) capture solvents and process modeling.