Ionic liquids/deep eutectic solvents for CO2 capture: Reviewing and evaluating

Abstract The CO2 solubilities (including CO2 Henry’s constant) in physical- and chemical-based ILs/DESs and the COSMO-RS models describing these properties were comprehensively collected and summarized. The summarized results indicate that chemical-based ILs/DESs are superior to physical-based ILs/DESs for CO2 capture, especially those ILs have functionalized cation and anion, and superbase DESs; some of the superbase DESs have higher CO2 solubilities than those of ILs; the best physical- and chemical-based ILs, as well as physical- and chemical-based DESs are [BMIM][BF4] (4.20 mol kg-1), [DETAH][Im] (11.91 mol kg-1), [L-Arg]-Gly 1:6 (4.92 mol kg-1) and TBD-EG 1:4 (12.90 mol kg-1), respectively. Besides the original COSMO-RS mainly providing qualitative predictions, six corrected COSMO-RS models have been proposed to improve the prediction performance based on the experimental data, but only one model is with universal parameters. The newly determined experimental results were further used to verify the perditions of original and corrected COSMO-RS models. The comparison indicates that the original COSMO-RS qualitatively predicts CO2 solubility for some but not all ILs/DESs, while the quantitative prediction is incapable at all. The original COSMO-RS is capable to predict CO2 Henry’s constant qualitatively for both physical-based ILs and DESs, and quantitative prediction is only available for DESs. For the corrected COSMO-RS models, only the model with universal parameters provides quantitative predictions for CO2 solubility in physical-based DESs, while other corrected models always show large deviations (>83%) compared with the experimental CO2 Henry’s constants.