Jie Wang,Yi Zhang,Ao Li,Jun Gao,Dongmei Xu,Lianzheng Zhang,Yinglong Wang
Extractive distillation with propyl propionate, butyl propionate and butyl butyrate as extractive solvents is adopted to separate the binary azeotrope isopropyl alcohol + isopropyl acetate. Through the relative volatility and x - y diagrams, the influence of the three entrainers on the vapour-liquid equilibrium (VLE) behaviour is also explored. The isobaric VLE data for the binary systems of isopropyl acetate + propyl propionate/ butyl propionate/butyl butyrate are determined at 101.3 kPa with a modified Rose type recirculating still, and the determined VLE data of the three systems containing isopropyl acetate are checked to be thermodynamically consistent according to the Herington and van Ness test. Finally, the NRTL, UNIQUAC and Wilson activity coefficient models are employed to correlate the measured data. After that, the corresponding binary interaction parameters for the investigated systems are obtained, which can provide a basis for the simulation and optimization of the extractive distillation process.
Qing Zhao,Mengjin Zhou,Haiyang Cheng,Jiuxu Ruan,Yangyang Wang,Zhaoyou Zhu,Peizhe Cui,Yinglong Wang,Jingwei Yang
Efficient recovery of isopropyl acetate and isopropanol from wastewater during esterification is important. An efficient separation process using ionic liquid mixed solvent extractive distillation (MSED) to separate azeotropic mixtures was proposed. The selectivity of 169 ionic liquids was calculated based on the COSMO–segment activity coefficient model for prescreening ionic liquids. The influence of the structure of the ionic liquids on the separation performance was further explored through molecular dynamics to determine 1-ethyl-3-methylimidazole acetate ([EMIM][AC]) as the best solvent. The vapor–liquid equilibrium of the system under the influence of [EMIM][AC] was measured to verify the model used for the calculation. A multi-objective genetic algorithm was used for optimizing the process parameters with the total annual cost (TAC) and gas emission as objective functions. An energy-saving heat-pump-assisted heat-integrated extractive distillation (HPHIED) process was proposed to realize heat recovery in MSED. The results showed that the TAC and gas emissions of MSED were 26.83% and 25.32%, respectively, lower than those of the single-organic solvent extractive distillation process. The TAC and gas emissions of HPHIED process were 11.02% and 35.83%, respectively, lower than those of MSED.
This study investigates the phase equilibrium behavior of the isopropyl acetate (IAC)-isopropanol (IPA) azeotrope system at 101.3 kPa in the presence of three different imidazolium-based ionic liquids (ILs) as entrainers, 1-butyl-3-methylimidazolium acetate ([BMIM][Ac]), 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([BMIM][NTf2]), and 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([HMIM][NTf2]). First, according to the measured vapor–liquid equilibrium (VLE) data of the binary system IAC(1)-IPA(2) and the ternary system IAC(1)-IPA(2)-ILs(3), [BMIM][Ac] in the ternary system produces a strong salting-in effect on IPA, while [BMIM][NTf2] and [HMIM][NTf2] produces a salting-in effect on IAC, and the effect of [BMIM][Ac] is much stronger than [BMIM][NTf2] and [HMIM][NTf2]. This work uses the nonrandom (local) two-liquid equation to correlate the VLE data. The mole fractions of [BMIM][Ac], [BMIM][NTf2], and [HMIM][NTf2] required to exactly eliminate the azeotropic point of the IAC-IPA system are 0.035, 0.144, and 0.206, respectively.
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