The Research On The Separation Of Azeotrope System With Ionic Liquids

The feasibility of using ionic liquids(ILs) as entrainers for the separationof the azeotropic mixtures of water and 2-propanol/1-propanol by extractivedistillation is researched in this study.In this study, a ebulliometer is established, based on this, a process ofexperimental measurement of vapor-liquid equilibria of ionic liauidscontaining systems in a way of vapor composition is obtained by sampling andanalysis, while the liquid composition is obtained on the basis of continuoussynthesis is proposed.T, x, y data were measured for four ternary systems containing water,1-propanol/2-propanol, [bmim][BF₄]/[emim][BF₄] at P=100 kPa and atseveral constant IL mass fractions. And boiling temperature data were alsomeasured at 100 kPa for the six binary systems containing1-propanol/2-propanol/water, [bmim][BF₄]/[emim][BF₄] six binary systems.From the experimental data, relative volatility and activity coefficients of thevolatile components were obtained. Results showed that [emim]⁺ enhancesrelative volatility of the volatile components favourably, but the ionic liquidswith [BF₄]^- are not fine enough in general. The experimental data werecorrelated by the NRTL model. And the ternary VLE data were alsocalculated by binary NRTL parameters, which were obtained fromcorrelations of the binary boiling temperature data.T, x, y data were measured for ternary systems containing water(1)-2-propanol(2)-IL(3) at 100 kPa, While the mole fraction of2-propanol calculated on the IL-free basis, x₂^′=0.95, activity coefficients ofthe volatile components as well as the relative volatility were obtained fromthe experimental data. Seven ILs were investigated, cation including [emim]⁺,[bmim]⁺; anion including [BF₄]^-, [N(CN)₂]^-, [OAc]^-, [Cl]^-. Results showedthat the activity coefficients are mainly decided by the anions; the interactionsof the anions with water and 2-propanol are in the order of [Cl]^-≈[OAc]^-＞[N(CN)₂]^-＞[BF₄]^-. The similar order cancels the effect of ILs in some extent.The interactions of the cations with water and 2-propanol are in the reversed:for water, [emim]⁺＞[bmim]⁺; for 2-propanol, [emim]⁺＜[bmim]⁺; this is infavor of enhancing the relative volatility of the volatile components. Amongthe systems investigated, the ILs with [OAc]^- or [Cl]^- as the anion, and[emim]⁺ as the cation, have the best separation effect. The VLE data werecorrelated by the NRTL model, from the correlation parameters, prediction ofVLE was obtained for the ternary system at different water concentrations.