Vapor–liquid equilibrium measurement and modeling for the difluoromethane + pentafluoroethane + propane ternary mixture

Vapor–liquid equilibrium data for the difluoromethane (R32) + pentafluoroethane (R125) + propane (R290) ternary mixture were measured at 5 isotherms between 263.15 K and 323.15 K. The measurement was carried out using a circulation-type apparatus recently developed, which was validated with binary mixtures. With binary interaction parameters obtained for the three corresponding binary mixtures, VLE modeling and prediction were performed for the ternary mixture using the Peng–Robinson equation of state with the classical mixing rules and MHV1 mixing rules. Hou's group contribution model for VLE of new refrigerant mixtures was further tested with the experimental data for the ternary system. The predicted pressure and vapor phase composition were compared with experimental ones.     

Liquid–liquid equilibria for water + 1-propanol/2-propanol + potassium chloride + cesium chloride quaternary systems at 298.1 ± 0.1 K

In this paper, we present the results of our study of the phase equilibria for two quaternary systems: water + 1-propanol/2-propanol + potassium chloride (KCl) + cesium chloride (CsCl) at 298.1 ± 0.1 K. We also produced the binodal curves and tie-lines at different KCl/CsCl mass-fraction ratios, and produced integrated phase diagrams for the quaternary systems. We also discuss the solvation abilities of KCl and CsCl, and the effect of the polarity of the organic solvent on the liquid–liquid equilibrium. We compared the experimental tie-lines derived for the quaternary systems with values predicated by modifying the Eisen–Joffe equation. The model produced satisfactory results.     

Vapor–liquid equilibrium for the binary systems tetrahydrothiophene + toluene and tetrahydrothiophene + o-xylene at 368.15 K and 383.15 K

Isothermal vapor–liquid equilibrium (VLE) for tetrahydrothiophene + toluene and tetrahydrothiophene + o-xylene at 368.15 K and 383.15 K was measured with a recirculation still. Liquid- and vapor-phase compositions were determined with gas chromatography. All systems exhibit a small positive deviation from Raoult's law and show nearly ideal behavior. All VLE measurements passed the point test used. The experimental results were correlated with the Wilson model and compared with COSMO-SAC predictive models. COSMO-SAC predictions show a slight negative deviation from Raoult's law for all systems measured. Raoult's law can be used to describe all systems studied. The activity coefficients at infinite dilution are presented.     

Measurement and calculation of vapor–liquid equilibria for methanol + glycerol and ethanol + glycerol systems at 493–573 K

The vapor–liquid equilibria for methanol + glycerol and ethanol + glycerol systems were measured by a flow method at 493–573 K. The pressure conditions focused in this work were 3.03–11.02 MPa for methanol + glycerol system and 2.27–8.78 MPa for ethanol + glycerol system. The mole fractions of alcohol in vapor phase are close to unity at the pressures below 7.0 MPa for both systems. The pressures of liquid saturated lines of the liquid phase for methanol + glycerol and ethanol + glycerol systems are higher than that for the mixtures containing alcohol and biodiesel compound, methyl laurate or ethyl laurate.     

Liquid–liquid equilibrium of (water + 1-propanol + 1-pentanol) system at 298.15 and 323.15 K

Liquid–liquid equilibrium data for the ternary system water + 1-propanol + 1-pentanol have been determined experimentally at 298.15 and 323.15 K using “static–analytic” apparatus involving ROLSI™ samplers. The experimental data are correlated considering both NRTL and UNIQUAC activity coefficient models. The results obtained show the ability of both models for the determination of liquid–liquid equilibrium data of the studied system. The reliability of the experimental tie-line data is determined through the Othmer–Tobias and Bachman equations.     

Vapor–liquid equilibria and density measurement for binary mixtures of o-xylene + NMF, m-xylene + NMF and p-xylene + NMF at 333.15 K, 343.15 K and 353.15 K from 0 kPa to 101.3 kPa

Isothermal vapor–liquid equilibria at 333.15 K, 343.15 K and 353.15 K for three binary mixtures of o-xylene, m-xylene and p-xylene individually mixed with N-methylformamide (NMF), have been obtained at pressures ranged from 0 kPa to 101.3 kPa over the whole composition range. The Wilson, NRTL and UNIQUAC activity coefficient models have been employed to correlate experimental pressures and liquid mole fractions. The non-ideal behavior of the vapor phase has been considered by using the Peng–Robinson equation of state in calculating the vapor mole fraction. Liquid and vapor densities were measured by using two vibrating tube densitometers. The excess molar volumes of the liquid phase were also determined. Three systems of o-xylene + NMF, m-xylene + NMF and p-xylene + NMF mixtures present large positive deviations from the ideal solution and belong to endothermic mixings because their excess Gibbs energies are positive. Temperature dependent intermolecular parameters in the NRTL model correlation were finally obtained in this study.     

Liquid–liquid equilibrium of the ternary system water + acetic acid + sec-butyl acetate

Experimental liquid–liquid equilibrium (LLE) of the water–acetic acid–sec-butyl acetate ternary system was investigated at 298.15, 303.15, 308.15 and 313.15 K and at atmospheric pressure. Separation factors were also evaluated for the immiscibility region. The NRTL and UNIQUAC models were applied to fit the experimental data for the ternary system. The binary interaction parameters obtained from both models were found to be successfully correlated with the equilibrium compositions. The UNIFAC group contribution method was employed to predict the observed ternary LLE data. It was found that four types of the UNIFAC model (UNIFAC, UNIFAC-LL, UNIFAC-DMD, and UNIFAC-LBY) did not provide a good prediction of the LLE data for this ternary system.     

Vapor–liquid equilibrium for binary system of tetrahydrothiophene + 2,2,4-trimethylpentane and tetrahydrothiophene + 2,4,4-trimethyl-1-pentene at 358.15 and 368.15 K

Isothermal vapor–liquid equilibrium (VLE) for tetrahydrothiophene + 2,2,4-trimethylpentane and tetrahydrothiophene + 2,4,4-trimethyl-1-pentene at 358.15 and 368.15 K were measured with a circulation still. All systems studied exhibit positive deviation from Raoult's law. No azeotropic behavior was found in all systems at the measured temperatures. The experimental results were correlated with the Wilson model and compared to COSMO-SAC predictive model. Analyses of liquid and vapor phase composition were determined with gas chromatography. All VLE measurements passed the three thermodynamic consistency tests used. The activity coefficients at infinite dilution are also presented.     

Ternary liquid–liquid equilibria for (water + terpene + 1-propanol or 1-butanol) systems at the temperature 298.15 K

Liquid–liquid equilibria and tie-lines for the ternary (water + 1-propanol + α-pinene, β-pinene or limonene) and (water + 1-butanol + α-pinene, β-pinene or limonene) mixtures have been measured at T = 298.15 K. The experimental ternary liquid–liquid equilibrium data have been successfully represented using the additional ternary parameters as well as the binary parameters in terms of the extended and modified UNIQUAC models.     

Measurement and correlation of liquid–liquid equilibria for ternary systems {cyclooctane + aromatic hydrocarbon + 1-ethyl-3-methylpyridinium ethylsulfate} at T = 298.15 K and atmospheric pressure

This work reports liquid–liquid equilibrium (LLE) results for the ternary systems {cyclooctane + benzene + 1-ethyl-3-methylpyridinium ethylsulfate}, {cyclooctane + toluene + 1-ethyl-3-methylpyridinium ethylsulfate}, and {cyclooctane + ethylbenzene + 1-ethyl-3-methylpyridinium ethylsulfate} at T = 298.15 K and under atmospheric pressure. The selectivity, percent removal of aromatic, and distribution coefficient ratio, derived from the tie-line data, were calculated to determine if this ionic liquid is a good solvent for the extraction of aromatics from cyclooctane. The phase diagrams for the ternary systems are shown, and the tie-lines correlated with the NRTL model have been compared with the experimental data. The consistency of the experimental LLE data was ascertained using the Othmer–Tobias and Hand equations. No data for mixtures presented here have been found in the literature.     

Isobaric vapor–liquid equilibria for water + n-propanol + n-butanol ternary system at atmospheric pressure

Isobaric vapor–liquid equilibrium (VLE) data for water + n-propanol + n-butanol ternary system have been extensively measured at 99.2 kPa using a recirculating still. The experimental data were then correlated using the extended UNIQUAC model, in which the binary interaction energy parameters between the three components were obtained through a simplex fitting method. The results showed that the calculated data by the extended UNIQUAC model using the same interaction energy parameters agree well with both the experimental data and the literature data. It demonstrated that the experimental data are very consistent with the literature data; and the extended UNIQUAC model is reliable to predict the VLE of the ternary system using the obtained interaction energy parameters.     

Vapor–liquid equilibria and phase densities at saturation of carbon dioxide + 1-butanol and carbon dioxide + 2-butanol from 313 to 363 K

Experimental vapor–liquid equilibria for the systems carbon dioxide + 1-butanol and carbon dioxide + 2-butanol were obtained from 313 to 363 K via a static-analytic set-up. A vibrating U-tube densitometer was coupled to this apparatus to perform simultaneous measurements of both saturated densities of the vapor and liquid phases. The suitability of this apparatus was checked by comparing the experimental vapor–liquid equilibrium and saturated density results with the literature data. The experimental vapor–liquid equilibrium data were correlated using the Peng–Robinson equation of state coupled to the Wong–Sandler mixing rules with good agreement; however densities using the same model were not satisfactorily represented.     

Liquid–liquid equilibrium of ternary systems 1-octyl-3-methylimidazolium hexafluorophosphate + aromatic + aliphatic hydrocarbons

The phase behavior of six ternary systems involving an aromatic hydrocarbon (benzene, toluene or m-xylene), an aliphatic hydrocarbon (nonane or undecane), and an ionic liquid (1-octyl-3-methylimidazolium hexafluorophosphate, [omim][PF₆]) was experimentally studied at 298.15 K and atmospheric pressure, totalizing 26 tie-lines. The main goal is to determine if [omim][PF₆] is a good solvent for the separation of the aromatic and aliphatic compounds, a common operation in the processing of reformed naphtha. All the ternary diagrams are of type 1, with high and wide two-phase regions, which show that [omim][PF₆] is a good solvent for the extraction of aromatic from aliphatic hydrocarbons. The Othmer–Tobias correlation was used for evaluation of the quality of the tie-line data, with good results. The data were correlated with the NRTL model for the activity coefficient, with estimation of new interaction energy parameters by using a modified Simplex method and a composition-based objective function. The results, expressed by root mean square deviations between experimental and calculated compositions, are very satisfactory.     

Isobaric vapor–liquid equilibrium for binary mixtures of 1-hexene + n-hexane and cyclohexane + cyclohexene at 30, 60 and 101.3 kPa

Consistent vapor–liquid equilibria (VLE) data were determined for the binary systems 1-hexene + n-hexane and cyclohexane + cyclohexene at 30, 60 and 101.3 kPa, with the purpose of studying the influence of the pressure in the separation of these binary mixtures. The two systems show a small positive deviation from ideality and do not present an azeotrope. VLE data for the binary systems have been correlated by the Wilson, UNIQUAC and NRTL equations with good results and have been predicted by the UNIFAC group contribution method.     

Isobaric vapour–liquid equilibria for the binary systems 4-methyl-2-pentanone + 1-butanol and + 2-butanol at 20 and 101.3 kPa

Isobaric vapour–liquid equilibrium (VLE) measurements for the binary systems 4-methyl-2-pentanone + 1-butanol and 4-methyl-2-pentanone + 2-butanol are reported at 20 and 101.3 kPa. The system 4-methyl-2-pentanone + 1-butanol presents a minimum boiling point azeotrope at both pressures (20 and 101.3 kPa) and the system 4-methyl-2-pentanone + 2-butanol presents only a minimum boiling azeotrope at 20 kPa. In both systems, which deviate positively from ideal behaviour, the azeotropic composition is strongly dependent on pressure. The activity coefficients and boiling points of the solutions were correlated with its composition by the Wilson, UNIQUAC, and NRTL models for which the parameters are reported.     

Isobaric vapor–liquid equilibria for the n-hexane + 2-isopropoxyethanol and n-heptane + 2-isopropoxyethanol systems

Vapor–liquid equilibria (VLE) for the n-hexane + 2-isopropoxyethanol and n-heptane + 2-isopropoxyethanol (at 60, 80, and 100 kPa) systems were measured. Two systems present positive deviations from ideal behavior. And the system n-heptane + 2-isopropoxyethanol shows a minimum boiling azeotrope at all pressures. Experimented data have been correlated with the two term virial equation for vapor-phase fugacity coefficients and the three suffix Margules equation, Wilson, NRTL, and UNIQUAC equations for liquid-phase activity coefficients. Experimental VLE data show excellent agreements with models.     

Liquid–liquid equilibria for {hexane + benzene + 1-ethyl-3-methylimidazolium ethylsulfate} at (298.2, 313.2 and 328.2) K

Liquid–liquid equilibria (LLE) for the ternary system {hexane + benzene + 1-ethyl-3-methylimidazolium ethylsulfate ([emim]C₂H₅SO₄)} have been measured at the temperatures (298.2, 313.2 and 328.2) K and atmospheric pressure. The reliability of the experimental data was tested using the Othmer–Tobias correlation. For the extractive effectiveness of the solvent, the distribution ratio and separation factor curves were plotted and compared with those of sulfolane. In addition, the LLE data were also correlated with UNIQUAC and NRTL models in a satisfactory manner.     

Solid–liquid equilibria of the ternary system m-nitrobenzoic acid + p-nitrobenzoic acid + acetone

Solubility data and the density of equilibrium liquid phase for the ternary system m-nitrobenzoic acid + p-nitrobenzoic acid + acetone were determined at 283.1 K and 313.1 K, and the phase diagrams of the system were constructed. Two solid phases, pure solid m-nitrobenzoic acid and p-nitrobenzoic acid are confirmed by the Schreinemaker's wet residue method. The crystallization regions of m-nitrobenzoic acid and p-nitrobenzoic acid increase as the temperature decreases. At the same temperature, the crystallization region of p-nitrobenzoic acid is larger than that of m-nitrobenzoic acid.     

Isothermal vapor–liquid equilibrium at 333.15 K,excess molar volumes and refractive indices at 298.15 K for mixtures of tert-amyl methyl ether + ethanol + 2,2,4-trimethylpentane

Isothermal vapor–liquid equilibrium data at 333.15 K are measured for the binary system tert-amyl methyl ether + ethanol and tert-amyl methyl ether + 2,2,4-trimethylpentane and for ternary system tert-amyl methyl ether + ethanol + 2,2,4-trimethylpentane by using headspace gas chromatography. The experimental vapor–liquid equilibrium data were correlated with G^E models (Margules, van Laar, Wilson, NRTL, UNIQUAC) equations. The excess volume and deviations in molar refractivity data are also reported for the same binary and ternary systems at 298.15 K. These data were correlated with the Redlich–Kister equation for the binary systems and the Cibulka equation for the ternary system, respectively. The experimental ternary excess volume and deviations in molar refractivity data, were also compared with the estimated values from the binary contribution models of Tsao–Smith, Kohler, Rastogi and Radojkovi?.     

Liquid–liquid equilibria for ternary systems of {cyclohexane + aromatic compounds + 1-ethyl-3-methylpyridinium ethylsulfate}

Liquid–liquid equilibrium (LLE) data for the ternary systems {cyclohexane + benzene + 1-ethyl-3-methylpyridinium ethylsulfate}, {cyclohexane + toluene + 1-ethyl-3-methylpyridinium ethylsulfate}, and {cyclohexane + ethylbenzene + 1-ethyl-3-methylpyridinium ethylsulfate} were determined at T = 298.15 K and atmospheric pressure. Selectivity, percent removal of aromatic, and solute distribution ratio, derived from the equilibrium data, were used to determine if this ionic liquid can be used as a potential solvent for the separation of aromatic compounds from cyclohexane. The phase diagrams for the ternary systems are shown, and the tie-lines correlated with NRTL model have been compared with the experimental data.