Wang, K.; Minceva, M.; Peng, D. Predicting liquid–liquid equilibria of deep eutectic solvent systems with UNIFAC: Application to aromatics extraction from pyrolysis gasoline. Chemical Engineering Science 2026, 322, 123130. doi.org/10.1016/j.ces.2025.123130

Abstract

Deep eutectic solvents (DESs), especially those based on choline chloride (ChCl), have emerged as greener and safer alternatives to conventional solvents in the liquid–liquid extraction process. However, the development of tailored DESs for specific extraction applications remains challenging due to the limited accuracy of current liquid–liquid equilibrium (LLE) prediction methods. To address this limitation, we applied the original UNIFAC model to 36 non-salt DES systems and extended group interaction parameters to include ChCl using experimental LLE data in 120 ChCl-based DES systems. The UNIFAC model showed good agreement with experimental data and significantly outperformed the COSMO-RS model (TZVPD-FINE parameter set) in predicting LLE for 156 DES systems. Notably, for 33 systems involving alkanes and aromatics, the UNIFAC model showed an accurate prediction, which is promising to be applied to screen suitable DESs for aromatics extraction from pyrolysis gasoline. Based on separation performance metrics (distribution constant, selectivity, extraction efficiency, and performance index) and physical property (melting point, viscosity, thermal stability, and greenness) constraints, ChCl:Sulfolane (1:3 mol:mol) was identified as the best solvent among 86 DES candidates. Process simulation and techno-economic analysis showed that the DES-based process provided high mass recovery (97.59 %) and purity (99 %) of aromatics, and a 50.86 % reduction in total annual cost compared to the conventional extraction process with sulfolane as solvent.

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