A density functional theory insight towards the rational design of ionic liquids for SO2 capture

Abstract

A systematic density functional theory (DFT) analysis has been carried out to obtain information at the molecular level on the key parameters related to efficient SO₂ capture by ionic liquids (ILs). A set of 55 ILs, for which high gas solubility is expected, has been selected. SO₂ solubility of ILs was firstly predicted based on the COSMO-RS (Conductor-like Screening Model for Real Solvents) method, which provides a good prediction of gas solubility data in ILs without prior experimental knowledge of the compounds' features. Then, interactions between SO₂ and ILs were deeply analyzed through DFT simulations. This work provides valuable information about required factors at the molecular level to provide high SO₂ solubility in ILs, which is crucial for further implementation of these materials in the future. In our opinion, systematic research on ILs for SO₂ capture increases our knowledge about those factors which could be controlled at the molecular level, providing an approach for the rational design of task-specific ILs.