COSMO-RS Studies: Structure–Property Relationships for CO₂ Capture by Reversible Ionic Liquids

The quantum-chemical approach COSMO-RS was used to develop structure–property relationships of reversible ionic-liquid (RevIL) solvents for CO₂ capture. Trends predicted for the thermodynamic properties of the RevILs using COSMO-RS, such as CO₂ solubility, solvent regeneration enthalpy, and solvent reversal temperature, were verified by experimental data. This method was applied to a range of structures, including silylamines with varying alkyl chain lengths attached to the silicon and amine functionality, silylamines with fluorinated alkyl chains, sterically hindered silylamines and carbon-based analogues. The energetics of CO₂ capture and release and the CO₂ capture capacities are compared to those of the conventional capture solvent monoethanolamine. The results of this study suggest that the simple COSMO-RS computational approaches reported herein can act as a guide for designing new RevILs. COSMO-RS allows for the determination of the relative thermodynamic properties of CO₂ in these and related systems