Modeling of phase separation solvent for CO₂ capture using COSMO-SAC model

Background: Phase separation solvents are proposed to replace conventional solvents for CO₂ capture due to a significant reduction of absorbent regeneration heat. A predictive approach based on COSMO-SAC is developed to model the CO₂ capture process using the phase separation solvent of 2-(ethylamino)ethanol (EAE) + water + diethylene glycol diethyl ether (DEGDEE). Methods: In this approach, liquid phase compositions, including CO₂ solubility, are determined from vapor-liquid-liquid equilibrium calculation with a chemisorption reaction in both liquid phases. The behavior of phase separation after CO₂ capture and CO₂ solubility in both CO₂-lean and CO₂-rich phases at 313 and 353 K can be well described by the proposed approach. Significant findings: The overall root-mean-square-deviation (RMSD) in predicting compositions (128 data points) of all components in both liquid phases is 0.064, which is slightly better than a previous study on the accuracy of COSMO-SAC in LLE prediction (RMSD = 0.105). The phase separation behavior of solvent can be realized with the hydrophilic product upon CO₂ absorption from the σ-profile analysis. The proposed framework is expected to be a useful tool for the development of a new phase separation solvent.