Liquid–liquid equilibria for the ternary system (phosphonium based deep eutectic solvent–benzene–hexane) at different temperatures: A new solvent introduced

In this work we studied the applicability of one ionic liquid analogues namely phosphonium based deep eutectic solvent (DES) in the extraction of aromatic hydrocarbons from aromatic/aliphatic mixtures. Experimental data for liquid–liquid equilibria (LLE) were obtained for various mixtures of (benzene + hexane + DES) at 27, 35 and 45 °C. Some of the mixtures showed excellent results in terms of aromatic selectivity and distribution ratio compared to what is currently used in industry. Chromatography analysis showed that the ethylene glycol used in forming the deep eutectic solvent was not present in the raffinate layer. This eliminates the step needed for the separation of the solvent. A comparative study of the separation effectiveness of the DES in this work with other reported ionic liquids as well as sulfolane was performed for choosing the best solvent for the intended separation.

► Mini review for previous researches for liquid–liquid extraction for aromatics separation from naphtha is presented.
► Usage of ionic liquids as solvents in aromatics separation is highlighted.
► Ionic liquid analogue is introduced as potential replacement for ionic liquids.
► Deep eutectic solvent is used for liquid–liquid extraction of aromatics separation for the first time.
► The deep eutectic solvent presented showed a satisfactory performance for extracting aromatics.