Measurement and prediction of isothermal vapor–liquid equilibrium of a-pinene+camphene/longifolene+abietic acid+palustric acid+neoabietic acid systems

The vapor–liquid equilibrium(VLE)data of a-pinene+camphene+[abietic acid+palustric acid+neoabietic acid]and a-pinene+longifolene+[abietic acid+palustric acid+neoabietic acid]systems at 313.15 K,333.15 K and 358.15 K were measured by headspace gas chromatography(HSGC).These data was compared with the predictions value by conductor-like screening model for realistic solvation(COSMO-RS).Moreover,the calculated data of COSMO-RS and Non-Random Two-Liquids(NRTL)models showed good agreement with the experimental data.It was found that the three resin acids inhibited the volatility of a-pinene,camphene and longifolene and resulted in the decrease of total pressure.Moreover,HE(HB)contributes the most to the excess enthalpy and the hydrogen bonding interaction is the dominant intermolecular force of a-pinene,camphene and longifolene with the three resin acids.In addition,the geometric structures optimization and binding energy were obtained by the DFT to further illustrate the hydrogen bonding interaction and the effects of the addition of the three resin acids on the isothermal VLE.

Liquid-Liquid Equilibrium for 1-Butanol-Water-KF and 1-Butanol-Water-K_2CO_3 Systems

KF or K2CO3 was added into the 1-butanol-water system and two phases were formed： water-rich phase （water phase） and 1-butanol-rich phase （1-butanol phase）. The liquid liquid equilibrium （LLE） data for 1-butanol-water-KF and 1-butanol-water-K2CO3 systems were measured at 25℃ and showed that 1-butanol phase contained negligible salt and water phase contained negligible 1-butanol when the concentrations of KF and K2CO3 in the water phase were equal to or higher than 27.11% and 31.68% , respectively. Thus water could be separated efficiently from 1-butanol-water by adding KF or K2CO3 into the system. A theoretical calculation of LLE data was calculated by using the Pitzer theory to get water activity in the water phase, and by the models, such as the Wilson, NRTL or the UNIQUAC for the 1-butanol phase. For 1-hutanol-water-KF system, the experimental data were found in good agreement with the calculated results by using Pitzer theory and Wilson equa tion, while for 1-butanol-water-K2CO3 system, the experimental data were found in good agreement with the calculated results by using Pitzer theory and UNIQUAC eauation.

Solid-Liquid Equilibrium of Terephthalic Acid in Several Solvents

Terephthalic acid(PTA) is practically one of the main materials of polyester. Its corresponding solid-liquid equilibrium data will provide essential support for industry design and further theoretical studies. In this work,solid-liquid equilibriums of terephthalic acid in four solvents, N,N-dimethylformamide, N,N-dimethylacetamide,dimethylsulphoxide and N-methyl-2-ketopyrrolidene, were determined in the temperature range from 293.15 K to 364.6 K by dynamic method. All these data were regressed by λh model, Wilson model and NRTL model, average absolute relative deviations of which are 1.25%, 15.02% and 7.22% respectively. It indicates that λh model is mostsuitable for description of the solid-liquid equilibrium containing PTA.

Isobaric Vapor-Liquid Equilibrium for Methyldichlorosi-lane+Methylvinyldichlorosilane+Toluene and Constituent Binary Systems

Vapor-liquid euilibrium (VLE) for a ternary system of Methyldichlorosilane+methylvinyldichlorosilane+toluene and constituent binary systems were measured at 101.3kPa using a new type of magnetical pump-ebulliometer,The equilibrium conpositions of the vapor phase of binary systems were calculated indirectly from the total pressure-temperature-liquid composition(pTx).The experimental data were correlated with the Wilson and NRTL(non-random two liquid )equations.The parameters of the Wilson moldel were employed to predict the ternary VLE data .The calculated boiling points were in good agreement with the experimental ones.

Effect of methylimidazolium-based ionic liquids on vapor–liquid equilibrium behavior of tert-butyl alcohol + water azeotropic mixture at 101.3 kPa

Three ionic liquids(ILs),1-ethyl-3-methylimidazolium bromine([EMIM]Br),1-butyl-3-methylimidazolium bromine([BMIM]Br),and 1-hexyl-3-methylimidazolium bromine([HMIM]Br),were used as the solvent for separation of {tert-butyl alcohol(TBA)+ water} azeotrope.Vapor–liquid equilibrium(VLE)data for {TBA + water + IL}ternary systems were measured at 101.3 k Pa.The results indicate that all the three ILs produce an obvious effect on the VLE behavior of {TBA + water} system and eliminate the azeotropy in the whole concentration range.[EMIM]Br is the best solvent for the separation of {TBA + water} system by extractive distillation among the three ILs.The experimental VLE data for the ternary systems are correlated with the NRTL model equation with good correlations.Explanations are given with activity coefficients of water and TBA,and the experimental VLE-temperature data for {TBA or water + IL} binary systems.

Isobaric Vapor-Liquid Equilibrium of Binary Systems： p-Xylene ＋ （Acetic Acid, Methyl Acetate and n-Propyl Acetate） and Methyl Acetate ＋ n-Propyl Acetate in an Acetic Acid Dehydration Process

The vapor-liquid equilibrium data of four binary systems (acetic acid +p-xylene, methyl acetate +n-propyl acetate, n-propyl acetate +p-xylene and methyl acetate +p-xylene) are measured at 101.33 kPa with Ellis equilibrium still, and then both the NRTL and UNIQUAC models are used in combination with the HOC model for correlating and estimating the vapor-liquid equilibrium of these four binary systems. The estimated binary VLE results using correlated parameters agree well with the measured data except the methyl acetate +p-xylene system which easily causes bumping and liquid rushing out of the sampling tap due to their dramatically different boiling points. The correlation results by NRTL and UNIQUAC models have little difference on the average absolute deviations of temperature and composition of vapor phase, and the results by NRTL model are slightly better than those by UNIQUAC model except for the methyl acetate +n-propyl acetate system, for which the latter gives more accurate correlations.

Vapour-Liquid Equilibrium with a New Ebulliometer：Ester＋Alcohol System at 0.5 MPa

A new dynamic ebulliometer is used to determine vapor-liquid equilibrium(VLE) data experimentally. In the equipment,both phases are recirculated. Its operation is a consequence of the Cotrell pump effect produced when the mixture is heated in a double-walled inverted vessel. The reliability of the apparatus is tested with the mixtures studied previously by various authors. VLE data for the binary systems of methyl acetate + methanol and the methyl acetate + ethanol at 0.5 MPa are determined. The experimental data are confirmed with the point-to-point test of van Ness,applying the Fortran program of Frendslund et al. In addition,the experimental results are com-pared with the UNIFAC(including different versions) and ASOG prediction models.

Vapor-Liquid Equilibrium Measurements and Modeling for Ternary System Water ＋ Ethanol ＋ 1-Butyl-3-methylimidazolium Acetate

Vapor-liquid equilibrium(VLE) data were measured for ternary system water + ethanol + 1-butyl-3methylimidazolium acetate([bmim][OAc]),in a relatively wide range of ionic liquid(IL) mass fractions up to 0.8.Six sets of complete T-x-y data were obtained,in which the mole fraction of ethanol on IL-free basis was fixed separately at 0.1,0.2,0.4,0.6,0.8,and approximate 0.98.The non-random-two-liquid(NRTL) and electrolyte non-random-two-liquid(eNRTL) equations were used for correlation,showing similar deviations.The ternary VLE was also modeled with the correlation from two data sets,with the mole fractions of ethanol on IL-free basis being 0.1 and approximate 0.98.The VLE data were also reproduced satisfactorily.With the eNRTL model,the root-mean-square deviation for temperature is 0.79 K and that for vapor-phase mole fraction is 0.0094.The calculations are in good agreement with experimental data.The effect of the IL on the VLE behavior of the volatile components is also illustrated.

Isobaric vapor–liquid equilibrium for ternary system of ethanol, ethyl propionate and para-xylene at 101.3 kPa

Isobaric vapor–liquid equilibrium(VLE) data for the binary system ethyl propionate(2) + para-xylene(3) and ternary system ethanol(1) + ethyl propionate(2) + para-xylene(2) at atmospheric pressure(101.3 k Pa)were obtained by a VLE modified othmer still. All the experimental data passed a point to point consistency test of Van Ness method, which verified the data reliability. The Wilson and UNIQUAC activity coefficient models were employed to correlate the binary VLE data to obtain binary interaction parameters. Based on binary interaction parameters, ternary VLE data of ethanol(1) + ethyl propionate(2) + para-xylene(3) were predicted by Wilson and UNIQUAC models, which proved that predicted values are consistent with the experimental data.Furthermore, azeotropic phenomenon between ethanol and ethyl propionate disappears when the mole ratio of para-xylene and binary system of ethanol and ethyl propionate is 1:1. Therefore, this paper convinced that para-xylene is a proper extractive additive that could be used in extractive distillation to separate the binary azeotropic system of ethanol and ethyl propionate.

Correlation and Prediction of Salt Effect on Vapor Liquid Equilibrium for the System of 2-Propanol/Water

Binary vapor liquid equilibrium (VLE) data were measured for the systems of 2-propanol/ ethanediol and ethanediol/potassium acetate (KAc). VLE data for the system of propanol/ethanediol was tested using thermodynamic consistency test. The average values of Δy1 and Δ P were 0.0776 and 0.1542 kPa, respectively. The above two sets of VLE data were correlated with the NRTL model. Ternary VLE data for the system of 2-propanol/water/KAc was used to obtain the more suitable parameters of NRTL model for binary systems of 2-propanol/KAc and water/KAc (called TDCM). For multicomponent systems, ternary and quaternary, the VLE values predicted by the NRTL model agreed well with the litera-ture data. Influence of KAc, ethanediol, and the mixture of KAc and ethanediol on volatility between 2-propanol and water was investigated respectively. The results showed that the above-mentioned materials and mixture had different influence on volatility between 2-propanol and water. The method for correla-tion and prediction of salt-containing VLE is simple and effective for the said system.

Prediction of Vapor-Liquid Equilibrium Data from C—H Band Shift of IR Spectra in Some Binary Systems

Prediction of vapor-liquid equilibrium (VLE) is extremely necessary to separate liquid mixture in chemical production, especially when the required experimental data are difficult to measure, or the measurement is not economical. The infinite dilution activities can be used to predict VLE. However, it needs both the ends of the activities that are difficult to obtain for many systems. In the present study, a new model is proposed for correlating the frequency shift of C H stretching band of IR spectra over the whole concentration. Investigated mixtures in-clude water/2-propanol, water/N, N-dimethylformamide (DMF), water/methanol, water/ethanol, water/1, 4-dioxane, and water/dimethylsulfoxide (DMSO) systems. Simultaneous correlations of C H frequency shift and VLE data are made. Furthermore, the VLE data were predicted with satisfactory results by the parameters obtained from IR spectra coupled with one of the infinite dilution activity coefficients.

Isobaric Vapor-Liquid Equilibrium of Binary System 2-Cyclohexen-l-one and 1,2-Epoxycyclohexane

Green oxidation of cyclohexene using dioxygen as oxidizing agent is highly desirable because of its environmental compatibility and economic impact.Separation of its oxidation products depends on the reliable vaporliquid equilibrium(VLE) data of relevant components,which are still lacking.The VLE data of binary system 1,2-epoxycyclohexane and 2-cyclohexen-1-one under ambient pressure were obtained using an improved VLE equipment EC-2 still in this work.The results showed that this binary system has no azeotropic point.Furthermore,the experimental VLE data were correlated with the Wilson thermodynamic model and the corresponding binary interaction parameters of the model were obtained.The results showed that the VLE data agreed well with the model and passed the thermodynamic consistency test of Herrington.

ISOBARIC VAPOR-LIQUID EQUILIBRIUMS OF OCTANE-ETHYL ACETATE AND OCTANE-ISOPROPYL ACETATE SYSTEMS

The isobaric vapor-liquid equilibrium data of systems of ethyl acetate（1）-n-octane（2） andisopropyl acetate（1）-n-octane（2） were determined at 0.0709 MPa and 0.1013 MPa by using a modifiedRose-Williams still.The experimental data were tested for thermodynamical consistency and correlatedsatisfactorily with p-T equation of state and Wilson equation.

Salt Effect on the Liquid-Liquid Equilibrium of （Water ＋ Propionic Acid ＋ Cyclohexanol） System at T=（298.2,303.2,and 308.2） K

Effects of salt and temperature on the liquid phase equilibrium of the(water + propionic acid + cyclohexanol) system were investigated.The liquid-liquid equilibrium data in the presence of KCl for various salt ionic strength of 0.5,1.0,1.5,2.0,and 2.5 mol·dm3 and in absence of the salt at T=(298.2,303.2,and 308.2)K were determined.The experimental results were correlated based on the Othmer-Tobias equation and Pitzer ion-interaction model.Thermodynamic properties such as distribution coefficients and activity coefficients of propionic acid in water + cyclohexanol were determined.In addition,the separation factor,S,of the chosen solvent was obtained for the investigated system.

Salt effect on the liquid–liquid equilibrium of the ternary (water + phenol + methyl isobutyl ketone) system: Experimental data and correlation

The effects of NaCl, KCl and Na_2SO_4 on the liquid–liquid equilibrium(LLE) data for the ternary system, water+ phenol + methyl isobutyl ketone, were determined at 0.101 MPa and 333.15 K and 343.15 K.The nonrandom two-liquid(NRTL) model was used to correlate the experimental data and to yield corresponding binary interaction parameters for these salt containing systems.The Hand and Othmer–Tobias equations were used to confirm the dependability of the determined LLE data in this work.Distribution coefficient and selectivity were used to evaluate the extraction performance of methyl isobutyl ketone with the existence of salt.The magnitude of salt effect on the water + phenol + methyl isobutyl ketone(MIBK) system is in the following order: Na_2SO_4>NaCl>KCl.

Isobaric vapor–liquid equilibrium for binary system of aniline+methyl-N-phenyl carbamate

In this study,the quasi-static ebulliometric method was used to measure both of the vapor pressures of methyl N-phenyl carbamate(MPC),and the isobaric vapor–liquid equilibrium(VLE) data of the aniline and MPC binary system.The measured vapor pressure data of MPC,at different temperature ranging from 369.60 to 389.54 K,fitted well with the Antoine equation.The VLE data for the aniline and MPC system at(2.00,4.00,6.00,7.00 and 8.00) k Pa were correlated by both of nonrandom two-liquid(NRTL) and Wilson models.The parameters of the two models were obtained by regressing the experimental data,with the absolute temperature deviations of 0.54 K and 0.53 K,respectively.The relative volatility of the binary system calculated was all far more than 1,which gives the conclusion that the high purity MPC can be separated from aniline and MPC binary system by rectification or distillation technology.

Measurements and correlation of liquid–liquid equilibrium data for the ternary(methyl tert-butyl ketone + o, m, p-benzenediol + water)system at(333.2, 343.2 and 353.2) K

In this work, liquid–liquid equilibria(LLE) data for the ternary system methyl tert-butyl ketone(MTBK)+ o, m,p-benzenediol + water were investigated at 333.2 K, 343.2 K and 353.2 K under 101.3 kPa. The performance of MTBK to extract o, m, p-benzenediol from wastewaters was estimated by partition coefficients and separation factors. The Hand and Bachman equations were both applied to check the reliability of the experimental LLE data. Furthermore, the Non-Random Two-Liquid(NRTL) and Universal Quasi Chemical(UNIQUAC) models were applied to correlate the measured LLE data. The results showed a good agreement with the determined ternary LLE data with the root-mean-square error(RMSE) values below 0.71%. MTBK was proved to be a promising extracting agent in extracting benzenediols from effluents.

Vapor-Liquid Equilibrium of Toluene-Polycyclic Aromatic Hydrocarbon System in Sub- and Supercritical State

The phase behaviors of toluene/polycyclic aromatic hydrocarbon mixture systems were investigated with a continuous-flow type apparatus at 573.2, 598.2, 623.2 and 648.2 K, while the pressure changed from 1 to 5MPa. The pseudo-binary phase behaviors were predicted with the Peng-Robinson equation of state with interaction parameters between toluene and pseudo-components considered. The phase diagrams of the system have been classified following the category of phase boundary diagram models. The extraction selectivity and efficiency of tolu-ene as a solvent was discussed by comparing with that of hexane. The prediction model for selectivity was also suggested.

Salt-Containing Extractive Distillation of 1-Propanol/Water System 1.Prediction of Salt Effect on Vapor Liquid Equilibrium

This paper has studied the vapor-liquid equilibrium (VLE) for the salt-containing extractive distillation of the 1-propanol/water system. Binary VLE data were measured for the systems of 1-propanol (1)/KAc (4), ethanediol (3)/KAc (4), and 1-propanol (1)/ethanediol (3), with the VLE data correlated with the NRTL model in order to obtain the model parameters of these binary systems. The binary VLE data cited in technical literature were correlated to obtain the model parameters for other binary systems. VLE data of ternary and quaternary systems predicted by the NRTL model agreed well with the literature data. The influence of KAc, ethanediol, and the KAc/ethanediol mixture on volatility between 1-propanol and water was investigated respectively. Test results showed that the above-mentioned materials (KAc, ethanediol) and their mixture (KAc and ethanediol) have different influence on the volatility. When x3=0.5, and x4=0.05, the azeotropic point can be eliminated. The NRTL model method of salt-containing VLE is simple and effective for the prediction of the system's VLE data.