Extractive distillation of the benzene and acetonitrile mixture using an ionic liquid as the entrainer

The benzene and acetonitrile azeotropic mixture was proposed to be separated by extractive distillation using an ionic liquid (IL) as the entrainer. The suitable IL was selected by the COSMO-RS model, and 1-ethyl-3-methylimidazolium tetrafluoroborate ([EMIM][BF4]) was considered as the suitable entrainer mainly due to its high selectivity, low viscosity, and low price. The experimental vapor pressure data of the IL-containing systems (benzene + [EMIM][BF4] and acetonitrile + [EMIM][BF4]) were measured in the full concentration range. The results show that acetonitrile has a stronger interaction with IL than benzene, and the low deviations between the experimental and UNIFAC predicted values show the reliability of the UNFIAC model. The UNIFAC predicted vapor–liquid equilibrium data of the benzene + acetonitrile + dimethyl sulfoxide (DMSO)/[EMIM][BF4] system show that the relative volatility of benzene to acetonitrile is higher when the entrainer is [EMIM][BF4]. The process simulation results show that [EMIM][BF4] can reduce the material and energy consumptions compared with DMSO.