Isobaric Vapor Liquid Equilibrium Research Articles

Isobaric Vapor–Liquid Equilibrium of the Acetonitrile + 1-Propanol + Ionic Liquids at an Atmospheric Pressure

The mixture of acetonitrile (1) + n-propanol (2) forms a binary azeotropic mixture at atmospheric pressure, which cannot be separated by common distillation. In this paper, the ionic liquids (ILs) 1,3-dimethylimidazolium dimethylphosphate ([MMIM][DMP]) and 1-ethyl-3-methylimidazolium diethylphosphate ([EMIM][DEP]) were used as solvents for separating the binary azeotropic mixture. The ternary isobaric vapor–liquid equilibrium data of acetonitrile (1) + n-propanol (2) + ILs (3) at atmospheric pressure in three IL mole fractions of 0.048, 0.091, and 0.131 were obtained. The results showed that the addition of [MMIM][DMP] or [EMIM][DEP] could enhance the relative volatility of acetonitrile to n-propanol, and the azeotropic point of the binary azeotropic system could disappear at the mole fractions of ILs above-mentioned. The effect of separation of ILs was in the order of [EMIM][DEP] > [MMIM][DMP]. The interaction parameters were obtained by fitting the nonrandom two-liquid (NRTL) model to the binary vapor–liquid equilibrium experimental data. The predicted results obtained using the NRTL model were in good agreement with the experimental data. In addition, a quantum chemical calculation based on Gaussian 09 at the B3LYP/6-311++G** level was also conducted. The calculated results indicated that the molecules of ILs had a stronger interaction with the n-propanol molecule than with the acetonitrile one.

Vapor Liquid Equilibria of 1-Ethyl-3-methylimidazolium Triflate (C2mimTfO) and n-Alkyl Alcohol Mixtures.

The isobaric vapor liquid equilibria (VLE) of different binary mixtures of the ionic liquid (IL) 1-ethyl-3-methylimidazolium trifluoromethanesulfonate (C2mimTfO) with the n-alkyl alcohols, methanol, ethanol, propan-1-ol, and butan-1-ol, are studied at the pressures of p = 500, 700, and 1000 mbar, covering a composition range 0.25-0.35 ≤ x(solvent) ≤ 1.0. Complementarily, the experimental results are compared with calculations by the perturbed-chain statistical associating fluid theory (PC-SAFT) equation of state (EoS). For deriving suitable PC-SAFT parameters, experimental liquid densities were determined for the neat IL C2mimTfO and its longer homologues, 1-butyl-3-methylimidazolium trifluoromethanesulfonate (C4mimTfO) and 1-hexyl-3-methylimidazolium trifluoromethanesulfonate (C6mimTfO), in a temperature range of 288.15 K ≤ T ≤ 363.15 K (C2mimTfO) and 293.15 K ≤ T ≤ 363.15 K (C4mimTfO and C6mimTfO), respectively. The PC-SAFT EoS is found to be suitable for describing the VLEs under study with good accuracy (AARDVLE ≤ 0.4%).

Experimental isobaric vapour-liquid equilibrium data for the binary system (N, N-dimethyl acetamide + dimethyl sulfoxide) and the quaternary system (sec-butyl acetate + sec-butyl alcohol + N, N-dimethyl acetamide + dimethyl sulfoxide) at 101.3 kPa

Isobaric vapour-liquid equilibrium (VLE) data for the binary system of {N, N-dimethyl acetamide (DMAC) + dimethyl sulfoxide (DMSO)} and the quaternary system of {sec-butyl acetate (SBAC) + sec-butyl alcohol (SBA) + DMAC + DMSO} were measured at 101.3 kPa using a modified Othmer still. The thermodynamic consistency test for the binary experimental data was checked by Van Ness point test. The experimental VLE data of the binary system were correlated with Wilson, NRTL and UNIQUAC activity coefficient models. The binary and quaternary VLE data predicted by the binary interaction parameters agreed well with the experimental data. And the mixed solvent (DMAC + DMSO) can eliminate the pseudo-azeotrope of SBAC and SBA. Thus the mixture of (DMAC + DMSO) is a potential extractive solvent in the separation of the pseudo-azeotrope of SBAC and SBA by extractive distillation.

Salts Effect on Isobaric Vapor–Liquid Equilibrium for the Azeotropic Mixture 2-Propanol + Water

Vapor–liquid equilibrium (VLE) data for the systems 2-propanol + water + calcium chloride, 2-propanol + water + magnesium chloride, 2-propanol + water + calcium nitrate, and 2-propanol + water + magnesium nitrate were measured at the pressure of 101.3 kPa. Experimental data of all ternary systems passed the thermodynamic consistency test by modified McDermott–Ellis method. Then, the effects of salts on the vapor phase mole fraction of 2-propanol and the relative volatility of 2-propanol to water were analyzed. Results show that the azeotropic point of the system 2-propanol and water can be removed with addition of the salts, and the salting-out effects follow the order calcium nitrate > calcium chloride > magnesium nitrate > magnesium chloride. Furthermore, the LIQUAC model was adopted to correlate the VLE experimental data of the systems. The comparative results of the average relative deviation (Δz̅) and the corresponding standard deviations (σ) between the experimental and calculated values indicate that LIQUAC model is suitable for the VLE calculation for the systems of 2-propanol + water + salts.

Ammonium-based deep eutectic solvent as entrainer for separation of acetonitrile–water mixture by extractive distillation

The increasing concern about environmental issues and the requirement to reduce the negative influence of industrial processes has directed the attention of scientific community toward the development of new green solvents. Recently, Deep Eutectic Solvents (DESs), which are ILs analogues have appeared as a promising substitutes to conventional volatile organic solvents. Unlike ILs, DESs offer inexpensive and easy synthesis, less toxicity and good biodegradability. In this study, ammonium-based deep eutectic solvent was synthesized and its feasibility was assessed as extracting agent for acetonitrile dehydration using extractive distillation. Glycolic acid and tetramethylammonium chloride (TMAC) based DES was prepared in 3:1 M ratio (GTM3:1) due to its well-known advantages over ionic liquids or organic molecular solvents. Isobaric vapor–liquid equilibrium data for pseudo-binary mixtures (acetonitrile–GTM3:1 & water–GTM3:1) were determined at 101.32 kPa. The pseudo-ternary VLE data of acetonitrile–water–GTM3:1 were also determined by keeping the concentration of DES nearly constant (x3 = 0.05, 0.10, and 0.15). The experimental data for these systems, were fitted using nonrandom two-liquid (NRTL) model and good correlation between predicted values and experimental data were obtained. From the results, GTM3:1 was capable of improving the relative volatility of the studied azeotropic mixture and successfully eliminated the azeotrope. The recoverability of used GTM3:1 was also investigated and the chemical properties of recovered GTM3:1 were found stable.

Influence of binary ionic liquid mixtures of [BMIM][Cl] and [BMIM][BF4] on isobaric vapor-liquid equilibrium of acetonitrile + water at atmospheric pressure

The effects of ionic liquid mixtures on the phase behavior of azeotropic mixture of acetonitrile + water were presented through the experimental determinations of isobaric vapor-liquid equilibrium for acetonitrile + water + 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF4]) and acetonitrile + water + 1-butyl-3-methylimidazolium chloride ([Bmim][Cl]) + [BMIM][BF4] at atmospheric pressure (101.3 kPa). The mole ratios of [BMIM][Cl] to [BMIM][BF4] in the mixing ILs were fixed at 2:1, 1:1 and 1:2, respectively. The results showed that [BMIM][BF4] was ineffective in breaking the azeotropy of acetonitrile and water, which whereas could be broken when [BMIM][Cl] reached a certain concentration in the mixing ILs. VLE data of ternary and quaternary mixtures were satisfactorily correlated and predicted with NRTL model and COSMO-SAC could give a reasonable prediction of VLE for the investigated mixtures. Additionally, the analysis of interactions among different molecules showed that the interactions between [BMIM][Cl] and water are strong while ones between [BMIM][BF4] and water weak.

Separation abilities of three acetate-based ionic liquids for benzene-methanol mixture through vapor-liquid equilibrium experiment at 101.3 kPa

Three ionic liquids (ILs) with acetate anion (1-hexyl-3-methylimidazolium acetate, [HMIM][OAC]; 1-octyl-3-methylimidazolium acetate, [OMIM][OAC]; and 1-decyl-3-methylimidazolium acetate, [DMIM][OAC]) were studied as entrainers for separating the benzene-methanol binary azeotrope. Isobaric vapor-liquid equilibrium (VLE) data for the ternary systems of benzene + methanol + IL were measured at 101.3 kPa. The VLE data were well correlated by using the nonrandom two-liquid (NRTL) model. The relative volatility of benzene to methanol is enhanced with the increase in IL content. The azeotropic phenomenon of benzene-methanol mixture can be completely eliminated when IL content reaches a specific value. After the azeotropy of benzene-methanol mixture is completely eliminated, the separation ability of the three ILs follows the order [HMIM][OAC] > [OMIM][OAC] > [DMIM][OAC]. The separation abilities of the three ILs were further analyzed with the help of their σ-profiles.

Isobaric vapor-liquid equilibrium of a ternary system of ethyl acetate + propyl acetate + dimethyl sulfoxide and binary systems of ethyl acetate + dimethyl sulfoxide and propyl acetate + dimethyl sulfoxide at 101.3 kPa

Isobaric vapor-liquid equilibrium data were measured for three systems, namely, ethyl acetate + dimethyl sulfoxide, propyl acetate + dimethyl sulfoxide and ethyl acetate + propyl acetate + dimethyl sulfoxide at 101.3 kPa in this work. The experimental data were checked by the Van Ness (point-to-point test) and Herington (integral test) methods. The binary systems’ vapor-liquid equilibrium data tested by experiments were fitted well with the NRTL, UNIQUAC and Wilson models. The binary interaction parameters regressed by the three models and experimental data were accepted to predict vapor liquid equilibrium data of a ternary system. The maximum absolute deviations and mean absolute deviations between the experimental and thermodynamic model data were within a reasonable range, indicating that corrected binary interaction parameters can be used to accurately predict vapor-liquid equilibrium data of the ternary system.

The thermodynamics and separation process design for the ternary system 1,3-propanediol + 1,3-butanediol + 2,3-butanediol

ABSTRACT The isobaric vapor–liquid equilibrium (VLE) data at 101.3kPa for (1,3-propanediol(PG) + 1,3-butanediol(BD)), (1,3-PG+2,3-BD) and (1,3-BD+2,3-BD) and for the ternary system of (1,3-PG+1,3-BD+2,3-BD) have been measured. The thermodynamic properties of the non-ideal vapor phase have been considered with the EOS equation. The liquid activity coefficients have been calculated with Wilson, NRTL and UNIQUAC equations, and the binary interaction parameters were regressed by these models. The vapor composition of VLE data were calculated by the optimum parameter group and generated a good consistency to experimental values. Based on all the preceding results, a two-column distillation process was designed.

Extractive Distillation with Ionic Liquid Entrainers for the Separation of Acetonitrile and Water

Ionic liquids (ILs) of 1-ethyl-3-methylimidazolium acetate ([EMIM][OAC]), 1-ethyl-3-methylimidazolium proline ([EMIM][PRO]), and N,N,N-dimethyl-butylethanol amine glycolic acid ([N1,1,4C2OH][GAC]) are selected as entrainers for the extractive distillation to separate the mixture of acetonitrile and water based on the COSMO-RS method. The isobaric vapor–liquid equilibrium of ternary mixtures containing ILs at atmospheric pressure is determined, verifying that the used ILs can break the azeotropy of acetonitrile and water. On the basis of the thermodynamic analysis, a typical extractive distillation process is designed with Aspen Plus to evaluate the competitiveness of IL entrainers in separation performance. Significant savings of entrainer and energy, in which the solvent ratios in moles reduce from 0.94 to 0.09, 0.12, and 0.12 and the overall heat duties on the reboiler decrease 24.9, 17.5, and 15.4% for [EMIM][OAC], [EMIM][PRO], and [N1,1,4C2OH][GAC], respectively, can be achieved compared with those of...

Separation of the mixture (isopropyl alcohol + diisopropyl ether + n-propanol): Entrainer selection, interaction exploration and vapour-liquid equilibrium measurements

For separation of the mixture {isopropyl alcohol (IPA) + diisopropyl ether (DIPE) + n-propanol (NPA)} by extractive distillation, propylene glycol ethyl ether (PGEE) was used as an entrainer based on selectivity since isopropyl alcohol + diisopropyl ether can an azeotrope. To explore the interaction mechanism between the entrainer PGEE and the components in the mixture, the charge density surface (σ-profiles) and the interaction energies were calculated based on the COSMO-SAC model and Dmol3, which could provide theoretical insight into interactions at the molecular level. Then, the data of isobaric vapour-liquid equilibrium (VLE) for (IPA + PGEE), (DIPE + PGEE) and (NPA + PGEE) systems were measured at 101.3 kPa. The NRTL, UNIQUAC and Wilson equations were applied to correlate the measured VLE data, and the thermodynamic model parameters for the binary systems were obtained by fitting the VLE data, which is helpful for the simulation and optimization of the separation process.

Determination of Ternary Vapor–Liquid Equilibrium of Dimethyl Oxalate–Methanol-1,2-Butanediol under Atmosphere Pressure

Isobaric vapor–liquid equilibrium (VLE) data for the dimethyl oxalate + methanol and methanol + 1,2-butanediol binary systems, as well as the VLE for the dimethyl oxalate + methanol + 1,2-butanedio...

Isobaric vapor-liquid equilibria for tert-butanol + water with single and mixed ionic liquids as solvents at 101.3 kPa

Ionic liquid 1-ethyl-3-methylimidazolium dicyanamide ([C2mim][DCA]) and a mixture of ionic liquids [C2mim][DCA] + 1-ethyl-3-methylimidazolium acetate ([C2mim][OAc]) were used as extractive distillation solvents to separate tert-Butyl alcohol (TBA) + water. The vapor-liquid equilibria for TBA + water + [C2mim][DCA] and TBA + water + [C2mim][DCA] + [C2mim][OAc] were measured at 101.3 kPa. The NRTL model was employed to correlate the vapor-liquid equilibrium data, and the binary interaction parameters were obtained. The experimental results show that both of the solvents can improve the relative volatility of TBA to water, and completely destroy the azeotropic point of TBA-water. There is no synergistic effects between [C2mim][DCA] and [C2mim][OAc], and the selectivity of [C2mim][OAc] is higher than that of [C2mim][DCA], but the viscosity of [C2mim][DCA] is lower.

Measurement and Correlation of Isobaric Vapor–Liquid Equilibrium for Camphene, (+)-3-Carene, and (±)-Limonene Systems

Isobaric vapor–liquid equilibrium (VLE) experimental data for camphene + (±)-limonene, camphene + (+)-3-carene, (±)-limonene + (+)-3-carene, and camphene + (+)-3-carene + (±)-limonene were determin...

Isobaric vapor–liquid equilibrium of three binary systems containing dimethyl succinate, dimethyl glutarate and dimethyl adipate at 2, 5.2 and 8.3 kPa

The isobaric vapor–liquid equilibrium (VLE) data for three binary systems of dimethyl succinate (DMS) + dimethyl glutarate (DMG), dimethyl succinate + dimethyl adipate (DMA) and dimethyl glutarate + dimethyl adipate were determined at 2, 5.2 and 8.3 kPa with a dynamic recirculating apparatus and the temperature ranged from 363.39 to 422.4 K. All the experimental data were verified to be thermodynamically consistent according to the Herington method and point to point method of Van Ness test. Afterwards, the VLE data were correlated with Nonrandom two-liquid (NRTL), Wilson and UNIQUAC activity coefficient models, and the interaction parameters of thermodynamic models of these three binary systems were obtained. The results indicated that the calculated values of these three models agreed well with the experimental data, while the NRTL model and UNIQUAC model provided a slightly better result than Wilson model. The calculated root mean square deviations of NRTL model for the temperature and vapor-phase mole fraction were less than 0.13 K, and 0.0023, respectively.

Experimental Determination of Isobaric Vapor–Liquid Equilibrium and Isothermal Interfacial Tensions for the Binary Ethanol + Cyclopentyl Methyl Ether Mixture

This work describes the vapor–liquid equilibrium (VLE) data experimentally measured at three isobaric conditions 50, 75, and 94 kPa and over the temperature range from 334 to 375 K and the atmospheric interfacial tensions (IFT) measured at the isothermal of 298.15 K in the whole mole fraction range for the ethanol + cyclopentyl methyl ether binary system. In order to carry out the experimental determinations, a dynamic all-glass Guillespie type cell was used to carry out VLE measurements, whereas a maximum differential bubble pressure tensiometer was used to IFT determinations. Because few experimental data are available for cyclopentyl methyl ether, vapor pressures and interfacial tensions have also been measured over the temperature range 341–378 K and 298–353 K, respectively. According to the experimental results, the binary system ethanol + cyclopentyl methyl ether displays a positive deviation from the Raoult’s law with a minimum temperature azeotropic over the whole explored pressure range. The azeo...

Deep eutectic solvents effect on vapor-liquid phase equilibrium for separation of allyl alcohol from its aqueous solution

Allyl alcohol and water can form an azeotrope with the minimum boiling point. To separate allyl alcohol from its aqueous solution by distillation, the deep eutectic solvents (DESs) were applied to eliminate the azeotropic point. Two DESs choline chloride: glycerin (mole ratio of 1:1) and choline chloride: urea (mole ratio of 1:2) were selected. To validate the selected DESs for separation of allyl alcohol from its aqueous solution, the isobaric vapor-liquid equilibrium (VLE) data for the system of allyl alcohol + water + DESs were measured at pressure of 101.3 kPa. The relative volatility of allyl alcohol to water increased significantly by adding the DESs. With increasing the concentrations of the DESs, the azeotropic point of the system allyl alcohol + water moved and the azeotropic point was broken at last. Then, the COSMO model provides some theoretical insights into the separation mechanism. Meanwhile, the experimental VLE data were correlated by the NRTL model and the correlated results agreed with the measured data.

Vapour-liquid equilibrium measurements and extractive distillation process design for separation of azeotropic mixture (dimethyl carbonate + ethanol)

Dimethyl carbonate and ethanol can form an azeotrope with the minimum boiling point. To separate the azeotrope (dimethyl carbonate + ethanol) by extractive distillation, p-xylene, butyl propionate, and isobutyl acetate were chosen as entrainers, and the isobaric vapour-liquid equilibrium (VLE) data for the binary systems of (dimethyl carbonate + p-xylene), (dimethyl carbonate + butyl propionate), (dimethyl carbonate + isobutyl acetate) and (ethanol + isobutyl acetate) were measured at 101.3 kPa using a modified Rose type recirculating still. The thermodynamic consistency of the VLE experimental data for the four binary mixtures was tested by the Herington and van Ness methods. Furthermore, the measured VLE data were correlated by the NRTL, UNIQUAC and Wilson thermodynamic models and the binary interaction parameters of the three models were regressed. Based above, an extractive distillation process with the entrainer of p-xylene was proposed and simulated to separate the azeotrope (dimethyl carbonate + ethanol).

Measurement and Correlation of Isobaric Vapor Liquid Equilibrium Data for Cyclopentyl Methyl Ether and Cyclopentanol

Isobaric vapor–liquid equilibrium data for pure components cyclopentyl methyl ether (CPME) and cyclopentanol (CP) and their binary mixtures was generated using a modified ebulliometer. This data has been reported for five different pressures in the range of 71.50 to 101.79 kPa. Pure component boiling points were correlated using the Antoine equation and compared with the literature data. Binary vapor–liquid equilibrium data was modeled using Wilson, NRTL, and UNIQUAC models. Deviation plots for experimental and predicted temperatures are given. UNIQUAC and NRTL model predictions showed a better fit with the experimental values relative to the Wilson model.

Experimental determination of vapor liquid equilibrium for methanol + methyl propionate + 1-butyl-3-methylimidazo-lium bis(trifluoromethylsulfonyl)imide at atmospheric pressure

Ionic liquid (IL) was selected as extractive distillation entrainer to separate the binary mixture of methanol and methyl propionate with the lowest azotropic temperature. Experimental determination of isobaric vapor-liquid equilibrium for the system of methanol + methyl propionate + 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([BMIM][NTf2]) was made at atmospheric pressure with an all-glass dynamic recirculating still. The results show that the addition of [BMIM][NTf2] can produce an obvious salting-out effect and well enhances the relative volatility of methanol to methyl propionate, and the azeotropy of the investigated binary system is ultimately eliminated by increasing the concentration of IL to a certain value in liquid phase. Additionally, the experimental data were well fitted with the NRTL model and the binary parameters were obtained.