The Study On Effects And Modeling Of Ionic Liquids For Two Azeotropic Systems

The special rectification method was often used to separate azeotropic systems in industrial production. In recent years, due to the rise of green chemistry, using ionic liquids as the extractant in extractive distillation technology has been developing rapidly. The vapor-liquid equilibrium (VLE) data of two azeotropic systems methanol-dimethyl carbonate (DMC) and methanol-methyl ethyl ketone have been measured at 101.3 kPa, [EMIM]OTf and [BMIM]OTf were also used as the extractant to separate them; The Wilson, NRTL, eNRTL and UNIQUAC models were adopted to correlate experimental data of the two systems, the UNIFAC model were adopeted to predict them. Specific work:1. The determination of VLE data. The VLE data of binary systems methanol-DMC and methanol-methyl ethyl ketone and the ternary systems methanol-DMC-[EMIM]OTf, methanol-DMC-[BMIM]OTf, methanol-methyl ethyl ketone-[EMIM]OTf and methanol-methyl ethyl ketone [BMIM]OTf were determined at 101.3 kPa.2. The experimental results. The ionic liquids reflected "salt effect" mechanism on azeotropic systems, the two azeotropic systems in this work reflected the "cross salt effect" of ionic liquids; the "cross salt effect" of ionic liquids on azeotropic systems increased with the increasing concentration; when [EMIM]OTf and [BMIM]OTf under the same concentration, the separation effect of them for the two azeotropic systems reflected the rules: [BMIM]OTf> [EMIM]OTf; for the two studied azeotrope in this paper, the same concentration of triflate ionic liquid of methanol-methyl ethyl ketone separation system was the most significant.3. Regression of activity coeffeicient models. The Wilson, NRTL, eNRTL and UNIQUAC four activity coeffeicient models were used to correlated the VLE data. The interaction parameters of these models were obtained, and the responding discussion was given according to the comparison with the experimental data.4. Regression and prediction of UNIFAC model. The UNIFAC model was used to correlate methanol-DMC system as well as the system containing [BMIM]OTf, the group interaction parameters of UNIFAC model were obtained, then the two systems containing [EMIM]OTf were predicted. The predicted values were close to the experimental values, which can indicate that the group parameters correlated by UNIFAC model can be used to judge whether the ionic liquid with the same group can be adopted as extractant.The VLE data containing ionic liquids was determined, also, the VLE data was correlated and predicted by thermodynamic model, the correspongding interaction parameters in model were obtained. It can provide theoretical surpport for using ionic liquids as the extractant in extractive distillation to separating methanol-DMC and methanol-methyl ethyl ketone systems.