Measurement And Correlation Of Isobaric Vapor Liquid Equilibria Of Azeotropic Systems With Ionic Liquids

Ionic liquids, as one kind of "green solvents", play an important role in the separation of azeotrope. This study main to comprehend the isobaric vapor-liquid equilibria of ethyl acetate-acetonitrile, methanol-THF and methanol-DMC with ionic liquids, based on the achievement in azeotrope separation situation at home and abroad. Then ?[CnMIM][NTf₂]: n=2?4?6?was chosen to separate the mixtures.The VLE for related binary and ternary containing ILs system was measured using the Modified Othmer still by designing the experiment scheme and improving measurement method. Furthermore, we pay attention to the effect that the ILs influence on the phase equilibrium composition, the relative volatility, activity coefficient, and the equilibrium temperature changes. After that, we determine the most appropriate ILs as extractant to separate the azeotropic mixtures.The experimental VLE data were associated with a variety of thermodynamic model and the theoretical value and experimental value has a good consistency. The long-range forces because of the electrostatic force between particles was corrected into the scope of activity coefficient based on Wilson model, then we suggest the Wilson-PDH model and study the factors that influence the long-range forces with ionic liquid and compared the results with other models. Conceptual design and Aspen Plus simulation on extractive distillation process with ionic liquids as extractant.1) Selection of appropriate ionic liquids: According to molecular structure characteristics of the ethyl acetate-acetonitrile, methanol-THF and methanol-DMC system, ?[CnMIM][NTf₂]: n=2?4?6? was chosen as suitable extractant for the extraction separation.2) Ethyl acetate-acetonitrile-ILs system: Measure the VLE data of ethyl acetate-acetonitrile, ethyl acetate-acetonitrile-[EMIM][NTf₂]/[BMIM][NTf₂]/[HMIM][NTf₂]. The minimum mole fraction to break azeotrope is that[EMIM][NTf₂]0.035, [BMIM][NTf₂]0.0270, and [HMIM][NTf₂]0.021 according to e-NRTL model.3) Methanol-THF-ILs system: Measure the VLE data of methanol-THF,methanol-THF-[EMIM][NTf₂]/[BMIM][NTf₂]/[HMIM][NTf₂]. The minimum mole fraction of ILs to break the azeotrope is that [EMIM][NTf₂]0.219,[BMIM][NTf₂]0.173,. and [HMIM][NTf₂]0.128 according to the e-NRTL model.4) Methanol-DMC-ILs system: Measure the VLE data of methanol-DMC and methanol-DMC-[HMIM][NTf₂]. The minimum mole fraction of ILs to break the azeotrope is 0.042 according to e-NRTL model.5) Correlated VLE data with thermodynamic model: Wilson, NRTL,e-NRTL and UNIQUAC associate the binary and ternary containing ionic liquid experimental VLE data and the related model parameters are obtained through the regression. For ethyl acetate-acetonitrile-ILs system, Wilson,NRTL, e-NRTL and UNIQUAC models have very good consistency with experimental value.6) Wilson-PDH model: Wilson-PDH is established to study the factors that influence the long-range forces on the contribution to the component activity coefficients. We focus on the effect of solvent dielectric constant,molar concentration and dissociation degree of ILs.7) Conceptual design and Aspen Plus simulation: Conceptual design on the extraction process that [HMIM][NTf₂] separate methanol-THF. Then simulate the process of extractive distillation separation system to study the reflux ratio, feed location, extraction solvent flow of ILs and withdrawl overhead product.