Enhancing aromatics extraction by double salt ionic liquids: rational screening-validation and mechanistic insights

Despite offering remarkable advantages as solvents, double salt ionic liquids (DSILs) have been scarcely studied for extractive dearomatization from hydrocarbons as well as many other applications, thus urging a theoretical guidance method. In this work, a systematic framework combining the rational screening-validation and mechanistic analysis is proposed for tailoring DSILs for the o-xylene/n-octane separation. From an initial pool of commercially available ionic liquids (ILs), key thermodynamic properties of paired DSILs are predicted by COSMO-RS while their important physical properties are estimated from those of corresponding parent ILs (retrieved from experimental database or predicted by a deep learning model). Promising DSILs are tested by liquid-liquid equilibrium experiments, wherein the ion ratio-effect is also evaluated. The mechanism underlying the tunability of DSIL thermodynamic properties is disclosed by means of quantum chemistry calculation and molecular dynamics simulation. This work can be a valuable reference for guiding the design of DSILs for diverse applications.