Systematic Method for Screening Ionic Liquids as Extraction Solvents Exemplified by an Extractive Desulfurization Process

For the selection of industrially suitable ionic liquids (ILs) as extraction solvents, a systematic method combining phase equilibrium calculation, physical property prediction, and process simulation is presented. The conductor-like screening model for real solvents is used to predict the liquid–liquid equilibria of the systems composed of the target mixture to be separated and different ILs at the specific global composition of interest, thereby prescreening ILs with higher mass-based distribution coefficient and selectivity as well as lower solvent loss. Group contribution methods are then employed to estimate the key physical properties of the prescreened ILs and further suggest candidates meeting certain physical property constraints. Afterward, the performance of the top IL candidates in a continuous process is analyzed by Aspen Plus to identify finally process-based optimal solvents. The proposed method is illustrated with an extractive desulfurization case study and two most promising ILs for this process are consequently determined.