Molecular mechanism and process of efficient separation of benzene and cyclohexane using a low-cost deep eutectic solvent

Abstract

In this work, we propose a deep eutectic solvent (DES) extractant for the separation of benzene (BEN) and cyclohexane (CYH) with a lower price and higher separation performance. First, 50 hydrogen bond acceptors (HBAs) and 31 hydrogen bond donors (HBDs) were screened using the COSMO-RS model. We selected NH4SCN:Sulfolane (1:3) for its physical properties and predicted eutectic points, and prepared it as the extractant. To further explore the structure–activity relationship, we analyzed the separation mechanism between DESs and BEN at the atomic scale, by quantum chemistry and molecular dynamic simulation. In addition, the liquid–liquid equilibrium data of the ternary system BEN-CYH-NH4SCN:Sulfolane were experimentally determined and used to fit the parameters of the NRTL model. Based on the NRTL model, the extraction combined extractive distillation process was simulated. We show that compared with the traditional process, the energy consumption and TAC of this process show great advantages to existing approaches.