Isothermal Vapor-liquid Equilibrium Data Research Articles

Measurements of isothermal vapor-liquid equilibrium for 2,3,3,3-tetrafluoroprop-1-ene + 1,1,1,2-tetrafluoroethane + propane system at temperatures from 283.15 to 323.15 K

Isothermal vapor liquid equilibrium (VLE) data of the alternative 2,3,3,3-tetrafluoroprop-1-ene + 1,1,1,2-tetrafluoroethane + propane ternary mixture over the temperature range of 283.15–323.15 K at 10 K intervals were measured using a circulation type apparatus. The experimental VLE data were correlated by Wilson-RK model, NRTL-RK model and PR-WS-MUNIFAC model. All of the models can well present the experimental data. The average absolute relative deviation (AARD) of pressure are within 0.60% and the maximum average absolute deviation (AAD) of vapor mass fraction is 0.0154 for the PR-WS-MUNIFAC model. Based on the UNIFAC (Dortmund) method, the two new functional groups of C2H2F and CH2F were divided and the relevant group parameters were obtained by fitting the experimental data.

Isothermal Vapor–Liquid Equilibrium for the 2-Pentanone (MPK) + 2-Methyl Propan-1-ol Binary Mixture

Isothermal vapor–liquid equilibrium (VLE) data were measured for binary mixtures of 2-pentanone + 2-methylpropan-1-ol at (343.15, 358.15, and 363.15) K. A glass dynamic recirculating still suitable for a subatmospheric to atmospheric pressure range was used for the VLE measurements. The excess thermodynamic properties, namely, the molar excess Gibbs energy (GE), heat of mixing (HE), and molar excess entropy (SE) were derived from the measured isothermal VLE data. The calculated infinite dilution activity coefficients for the system are also presented. The measured isothermal VLE data for the binary system was regressed using the gamma–phi (γ–Φ) approach. The Wilson and the nonrandom two-liquid (NRTL) activity coefficient models were employed for the data regression, while the Hayden and O’Connell correlation was used to account for the nonidealities in the vapor phase. Satisfactory results were obtained using the Wilson and NRTL models to represent the measured data. The measured VLE data were considered ...

Isothermal Vapor–Liquid Equilibrium Data for Water + Diisopropanolamine, Water + N-Methyldiethanolamine and Diisopropanolamine + N-Methyldiethanolamine Systems

Accurate modeling of thermodynamic vapor–liquid equilibrium of aqueous amines and amine mixtures is essential for the design of new CO2 capture processes. Isothermal vapor–liquid equilibrium data were measured for the binary systems of water + diisopropanolamine (DIPA), water + N-methyldiethanolamine (MDEA) and DIPA + MDEA by using headspace gas chromatography at 423 K. The DIPA + MDEA system has azeotrope. The experimental binary vapor–liquid equilibrium data of water + DIPA, water + MDEA and DIPA + MDEA binary systems were well correlated with NRTL model.

Dibutyl Citrate Synthesis, Physicochemical Characterization, and Px Data in Mixtures with Butanol

Dibutyl citrate (DBC) was synthesized via partial esterification of citric acid (CA) with n-butanol (BuOH) and characterized for the first time. Then, the monoacid diester was isolated from the reactive mixture by using a pH-controlled solvent extraction procedure. The identity of the obtained product was verified by NMR spectroscopy, finding that it corresponds to a mixture of asymmetric and symmetric isomers. The obtained product was characterized by thermogravimetric and differential scanning calorimetry analysis and by density and viscosity measurements. As per the calorimetric analysis, DBC exhibited a crystallization point below 213 K, a decomposition temperature of 541 K, and an average heat capacity of 2.461 kJ/kg K in the evaluated temperature range (320–375 K). The average liquid density and viscosity in the studied temperature interval (298–313 K) were 1.122 g/cm3 and 2.03 Pa·s, respectively. Additionally, isothermal vapor–liquid equilibrium data (P–x) in mixtures containing the obtained DBC an...

Isothermal Vapor-Liquid Equilibrium of Methanol + Glycerol and 1-Propanol + Glycerol

Isothermal vapor-liquid equilibrium (VLE) data for two binary mixtures of methanol + glycerol and 1-propanol + glycerol were determined at the temperature range from (313.15 to 363.15) K using a simple quasi-static ebulliometer. All systems showed that the vapor pressures increased with increasing alcohols (methanol or 1-propanol) concentrations at corresponding system. The Wilson, Non-Random Two-Liquid (NRTL) and Universal Quasi-Chemical (UNIQUAC) activity coefficient models were used to correlate the experimental data. Both systems showed slightly deviations from the ideal liquid phase behavior.

Isothermal vapour-liquid equilibrium data for the binary systems of CHF3 with (n-nonane, n-decane, or n-undecane) and C2F6 with (n-nonane or n-decane)

The isothermal vapour-liquid and vapour-liquid-liquid equilibria of five binary refrigerant + n-alkane systems at near ambient temperatures were measured using a static-analytic apparatus and a static-synthetic apparatus. The phase equilibrium data for the systems of trifluoromethane (R-23) + n-nonane and hexafluoroethane (R-116) + n-decane were measured using the static-analytic apparatus, whereas bubble point data were measured with the static-synthetic apparatus for the systems of R-23 + n-decane, R-23 + n-undecane and R-116 + n-nonane. The temperatures that were investigated for these systems ranged between (272.9 and 323.1) K.The experimental phase equilibrium data were modelled with the PR EOS and the MC alpha function. The WS mixing rule, incorporating either the NRTL or the UNIQUAC activity coefficient model, was used to apply the model to the mixture data. The temperature independent forms of the thermodynamic model were found to provide a more accurate representation of the experimental data than the temperature dependent forms. A single mixture critical point was determined using the indirect extended scaling laws of Ungerer et al. (2005). The calculation procedure of Heidemann and Khalil (1980) was used to estimate segments of the critical locus curves for the binary systems for which data were measured close to the critical locus curve. The van Konynenburg and Scott classification for each system was defined, based upon the characteristics of the critical locus curves within the temperature ranges that were studied.

Measurement and Prediction of Vapor–Liquid Equilibria in Ternary Systems Containing an Organic Component, Cyclohexylamine, and Cyclohexanol

The isothermal vapor–liquid equilibrium data are presented for three ternary systems: octane + cyclohexylamine + cyclohexanol, cyclohexane + cyclohexylamine + cyclohexanol, and toluene + cyclohexylamine + cyclohexanol. The experimental data were determined by the dynamic method in a modified Rock and Sieg circulation still at two different temperatures and reduced pressures. The experimental results were compared with the predictions from both UNIQUAC and NRTL activity coefficient models and the equation of state proposed by Elliott, Suresh, and Donohue (ESD EOS).

Vapor liquid equilibria for binary mixtures of difluoromethane (R32) + fluoroethane (R161) and fluoroethane (R161) + trans-1,3,3,3-tetrafluoropropene (R1234ze(E))

Abstract Developing new refrigerants with low global warming potential (GWP) is the major challenge for the refrigeration industry with the Paris Agreement going into effect on 4 November 2016. In this work, we reported the isothermal vapor liquid equilibrium (VLE) data for the low GWP binary refrigerants of difluoromethane (R32) + fluoroethane (R161) and fluoroethane (R161) + trans-1,3,3,3-tetrafluoropropene (R1234ze(E)). The measurements were carried out with a quasi-static analytical apparatus along five isotherms from (283.15 to 323.15) K. The experimental data were correlated by Peng-Robinson-Stryjek-Vera equation of state combined with the Wong and Sandler mixing rule and the non-random two-liquid activity coefficient (PRSV + WS + NRTL) model. The correlated results and the experimental data show good consistency. The average absolute deviation of pressure (AAD(p)) and average absolute deviation of vapor phase mole fraction (AAD(y)) are 0.12% and 0.0011 for R32 + R161, 0.20% and 0.0014 for R161 + R1234ze(E), respectively.

Measurement and Correlation of High Pressure Phase Equilibria for CO2 + Alkanes and CO2 + Crude Oil Systems

An analytical apparatus with improved recirculating and sampling mechanisms was presented to investigate phase behavior of binary and multicomponent systems, which effectively avoided undesirable pressure gradients across the cell and serious disturbance of equilibrium during sampling procedure. Two one-channel magnetic recirculation pumps were designed and built to provide better mass transfer between the coexisting phases. Two six-port switching valves were used for sampling, quantitative fluid injection, and online compositional analysis by gas chromatography. The apparatus was validated by means of isothermal vapor–liquid equilibrium data for CO2 + hexane, and the results were found to be in good agreement with the literature data. High pressure phase equilibria data of CO2 + n-alkanes and CO2 + crude oil + n-alkanes were measured from 353.15 to 373.15 K. Three thermodynamic models of RR, PRSV, and YQE, based on Peng–Robinson and a modified quartic equation of state coupled with various mixing rules, ...

Isothermal Vapor–Liquid Equilibrium Data for the Hexafluoroethane (R116) + n-Butane System at Temperatures from 273 to 323 K

Isothermal vapor–liquid equilibrium (VLE) data for the system of hexafluoroethane (R-116) + n-butane are reported in this paper. The measurements were undertaken at six different temperatures ranging from 273.27 to 323.19 K, with pressure ranging from 0.104 to 3.742 MPa. Two of the temperature sets were measured below, and the remaining four were measured above, the critical temperature of R116. The measurements were performed in a “static-analytic” type VLE apparatus. The sampling of the equilibrium phases was performed via pneumatic ROLSI capillary samplers (Armine’s patent). The equipment was developed in the CEP/TEP laboratory at MINES ParisTech. Combined expanded uncertainties in the measurements were estimated to be 0.02 K for temperature, 0.0006 MPa for pressure, and maximum of 0.004 for composition, based on the NIST guidelines. Each set of isothermal vapor–liquid equilibrium data was correlated with the Peng–Robinson equation of state (PR-EOS). The Mathias–Copeman alpha function, and the Wong–San...

Measurement and correlation of the isothermal VLE data for the binary mixtures of cyclopentene (CPEN)+cyclopentyl methyl ether (CPME)

The isothermal vapor-liquid equilibrium data for the binary systems of cyclopentene (1)+cyclopentyl methyl ether (2) were measured at 313.15, 323.15, 333.15, 343.15 and 353.15 K using a dynamic-type equilibrium apparatus and online gas chromatography analysis. For all the measured VLE data consistency tests were performed for the verification of data using Barker’s method and the ASPEN PLUS Area Test method. All the resulting average absolute values of residuals [δ ln (γ 1/γ 2)] for Barker’s method and D values for the ASPEN PLUS area test method were comparatively small. So, the VLE data reported in this study are considered to be acceptable. This binary system shows negative deviation from Raoult’s law and does not exhibit azeotropic behavior at whole temperature ranges studied here. The measured data were correlated with the P-R EoS using the Wong-Sandler mixing rule. The overall average relative deviation of pressure (ARD-P (%)) between experimental and calculated values was 0.078% and that of vapor phase compositions (ARD-y (%)) was 0.452%.

Isothermal vapour-liquid equilibrium data for the binary systems 2-propanone + (2-butanol or propanoic acid)

Isothermal vapour-liquid equilibrium (VLE) data were measured for 2-propanone + 2-butanol at (333.15 and 353.15) K and 2-propanone + propanoic acid at (333.15, 353.15, and 373.15) K. For the sub-atmospheric pressure measurements, a dynamic recirculating VLE glass still operated isothermally was used, whilst a novel recirculating stainless steel of similar architecture, capable of operating at pressures up to 750 kPa was used for measurements above atmospheric pressures. The experimental VLE data for the 2-propanone + 2-butanol system at (333.15 and 353.15) K were correlated to the Wilson and NRTL models using the gamma-phi approach with the Hayden and O'Connell correlation employed for calculating the second virial coefficients. For the 2-propanone + propanoic acid system, the considerably more complex iterative procedure of Prausnitz et al. [J.M. Prausnitz, T.F. Anderson, E.A. Grens, C.A. Eckert, R. Hsieh, J.P. O'Connell, Computer Calculations for Multicomponent Vapour-Liquid and Liquid-Liquid Equilibrium, Prentice- Hall, New Jersey, 1980] was utilized to account for acid dimerization in the vapour phase. In the computational procedure for finding liquid phase activity coefficients, true species vapour phase mole fractions (ηi) are solved for, with the equilibrium association constant, Ki emerging from the computations. The thermodynamic consistency of the data was verified through the point and direct test methods of Van Ness.

A comparative study of pure ionic liquids and their mixtures as potential mass agents in the separation of hydrocarbons

In this work, a study about the use of pure ionic liquids (ILs) and mixtures thereof as mass agents in the selective separation of n-heptane and toluene was carried out in order to compare the behavior of the ILs mixtures and the corresponding pure ILs. For that, the isothermal vapor-liquid equilibrium (VLE) data for {n-heptane+toluene+1-ethyl-3-methylimidazolium tricyanomethanide ([EMim][TCM])+1-ethyl-3-methylimidazolium dicyanamide ([EMim][DCA])} and {n-heptane+toluene+[EMim][TCM]} mixtures were experimentally determined at several temperatures over the whole composition range within miscibility region. The experimental VLE data obtained in this work were compared with those previously published for {n-heptane+toluene+[EMim][DCA]}. Finally, the experimental VLE data, which were obtained using a static headspace gas chromatograph (HS-GC), were adequately correlated using the non-random two liquids (NRTL) thermodynamic model.The obtained results confirm that ILs have an important effect on the VLE of systems containing n-heptane and toluene, which shows that these ionic solvents could be a promising alternative to carry out a selective separation of these hydrocarbons.

Isothermal vapour-liquid equilibrium data for the binary systems of (CHF3 or C2F6) and n-heptane

Isothermal vapour-liquid equilibrium (VLE) values for two binary systems; trifluoromethane and n-heptane at temperatures between T=(272.9 and 313.2)K, and hexafluoroethane and n-heptane at temperatures between T=(293.0 and 313.2)K were measured with a static-analytic apparatus. Bubble pressures at temperatures between T=(293.0 and 313.2)K, at several compositions, were also measured with a variable-volume static-synthetic apparatus. Vapour-liquid-liquid equilibrium (VLLE) was found to occur for certain isotherms for both of the systems. The PR EOS, with the Mathias-Copeman (MC) alpha function, combined with either the classical mixing rule or the Wong-Sandler (WS) mixing rule was used to correlate the experimental results. Either the NRTL or the UNIQUAC activity coefficient model was used within the WS mixing rule.The indirect extended scaling laws of Ungerer et al. were used to extrapolate critical loci from the experimental coexistence data, and the calculation procedure of Heidemann and Khalil was employed to calculate the mixture critical locus curves at temperatures close to the refrigerant critical temperatures. At lower temperatures on the mixture critical curve, gas-liquid critical points occurred, whereas, at higher temperatures, the critical points occurred along a liquid-liquid locus curve. The two systems were categorised according to the van Konynenburg and Scott classification.

Phase equilibrium data for binary mixtures of carbon dioxide with {1,1,2,3,3,3-hexafluoro-1-propene or 2,2,3-trifluoro-3-(trifluoromethyl)oxirane} at temperatures between (233 and 273) K

Isothermal vapour-liquid equilibrium data were measured for binary mixtures of carbon dioxide with either hexafluoropropylene or hexafluoropropylene oxide at five temperatures in the (233–273) K range. The experimental data presented in this manuscript supplement data which were previously measured at temperatures of 273 K and above. The data is required for the assessment of the operating conditions for a purification process for the production of high purity hexafluoropropylene oxide from a mixture of hexafluoropropylene and hexafluoropropylene oxide. The experimental P-x-y data were measured using an apparatus based on the “static-analytic” method. The experimental data were satisfactorily correlated using the Peng-Robinson Equation of State with the Mathias-Copeman alpha function.

Isothermal Vapor–Liquid Equilibrium Data for the Methanol + Benzene + Tetraphenylphosphonium Chloride System

Isothermal vapor–liquid equilibrium data for the system methanol + benzene + tetraphenylphosphonium chloride at four salt molalities {(0.100, 0.200, 0.300, and 0.500) mol·kg–1} have been measured with the help of headspace gas chromatography at {(308.15 and 328.15) K}. Tetraphenylphosphonium chloride can be used as an entrainer for the separation of methanol + benzene mixture. The experimental data were correlated using the electrolyte NRTL model.

Vapor-liquid equilibria for the binary mixtures of dimethyl ether (DME)+ dimethyl carbonate (DMC)

Isothermal vapor-liquid equilibrium data for the binary system of dimethyl ether (DME)+dimethyl carbonate (DMC) were measured at 303.15, 313.15, 323.15, 333.15 and 343.15 K using a circulation-type equilibrium apparatus with on-line gas chromatography analysis. The experimental data were correlated with the Peng-Robinson equation of state (PR-EoS) using the van der Waals one fluid mixing rule and the Peng-Robinson equation of state (PR-EoS) using the Wong-Sandler mixing rule combined with the NRTL excess Gibbs free energy model. This system showed negative deviation from Raoult’s law, and no azeotropic behavior was observed for all the temperature ranges studied here. Calculated results with PR-EoS using both two mixing rules showed good agreement with experimental data.

Use of selective ionic liquids and ionic liquid/salt mixtures as entrainer in a (vapor + liquid) system to separate n-heptane from toluene

During the last years, a large number of studies have evaluated the ability of ionic liquids (ILs) to separate aromatic from aliphatic hydrocarbons by liquid extraction. Nevertheless, in order to design a global process, a post-extraction step based on the aromatic recovery from the extract stream and the regeneration of the IL is required. Taking into account the negligible vapor pressure of the ILs, the use of separation units based on the difference of volatility among the components of the extract could be an appropriate way. However, that requires additional (vapor+liquid) equilibrium (VLE) data, which are scarce today. In this work, the isothermal VLE data for {n-heptane+toluene+1-ethyl-3-methylimidazolium thiocyanate ([EMim][SCN])} and {n-heptane+toluene+1-butyl-3-methylimidazolium thiocyanate ([BMim][SCN])} mixtures were experimentally measured at T=(323.2, 343.2 and 363.2)K over the whole composition range within the rich-IL miscibility region. For that, a static headspace gas chromatograph (HS-GC) was used. In addition, the non-random two liquids (NRTL) thermodynamic model was satisfactory applied to correlate the experimental VLE data.Finally, the effect of thiocyanate-based inorganic salts (AgSCN, Co(SCN)2 and CuSCN) on the phase behavior of the above mentioned mixtures were also analyzed through the experimental determination of the isothermal VLE of the pseudo-ternary systems {n-heptane+toluene+[EMim][SCN]/salt mixture}.The obtained results show that the use of pure thiocyanate-based ILs as entrainer increases the n-heptane relative volatility from toluene whereas the addition of inorganic salts has not led to an improvement of these results.

High-pressure phase equilibria data for mixtures involving ethene and perfluoro-n-octane from 293 to 353 K

Isothermal vapour–liquid equilibrium data were measured for ethene+perfluoro-n-octane mixtures at five temperatures in the 293–353K range, and pressures up to 8MPa. Experimental P–x–y data were measured using an apparatus based on the “static–analytic” method. The experimental data were correlated with a model comprising the Peng–Robinson equation of state with either the classical mixing rule or the Wong–Sandler mixing rule coupled with the Non-Random Two-Liquid activity coefficient model. The model gave good representation of the experimental data.

Phase equilibrium data for mixtures involving 1,1,2,3,3,3-hexafluoro-1-propene with either propane or n-butane between 312 and 343 K

Isothermal vapour–liquid equilibrium data are presented for binary mixtures of 1,1,2,3,3,3-hexafluoro-1-propene with either propane or n-butane in the (312–343)K temperature range. The experimental phase equilibrium data were measured using an apparatus based on the “static-analytic” method. The experimental data were correlated with a thermodynamic model comprising of the Peng–Robinson equation of state with the Mathias–Copeman alpha function, the Wong–Sandler mixing rule, and Non-Random Two-Liquid activity coefficient model. The model provided a very satisfactory correlation of the experimental data for both binary systems.