Modelling (vapour + liquid) and (vapour + liquid + liquid) equilibria of {water (H2O) + methanol (MeOH) + dimethyl ether (DME) + carbon dioxide (CO2)} quaternary system using the Peng–Robinson EoS with Wong–Sandler mixing rule

The (vapour + liquid) equilibria (VLE) and (vapour + liquid + liquid) equilibria (VLLE) binary data from literature were correlated using the Peng–Robinson (PR) equation of state (EoS) with the Wong–Sandler mixing rule (WS). Two group contribution activity models were used in the PRWS: UNIFAC–PSRK and UNIFAC–Lby. The systems were successfully extrapolated from the binary systems to ternary and quaternary systems. Results indicate that the PRWS–UNIFAC–PSRK generally displays a better performance than the PRWS–UNIFAC–Lby.     

Solubility of thiophene in carbon dioxide and carbon dioxide + 1-propanol mixtures at temperatures from 313 to 363 K

Solubility measurements of sulfur compounds in supercritical fluids are required in order to determine the feasibility of supercritical extraction for removing them from gasoline and diesel fuel. In this work, solubility of thiophene in CO₂ and in CO₂ + 1-propanol mixtures were measured from 313 to 363 K using an apparatus based on the static–analytical method. Vapor–liquid equilibria (VLE) data of binary mixtures were fitted to the Peng–Robinson equation of state (EoS) with classical mixing rules. The binary interaction parameters (k_ij) obtained were used to predict the VLE data of ternary systems. The calculated values given by this simple model agree well to the experimental data.     

High-pressure vapor–liquid and vapor–liquid–liquid equilibria in the carbon dioxide + 1-heptanol system

Vapor–liquid equilibria (VLE) and vapor–liquid–liquid equilibria (VLLE) data for the carbon dioxide + 1-heptanol system were measured at 293.15, 303.15, 313.15, 333.15 and 353.15 K. Phase behavior measurements were made in a high-pressure visual cell with variable volume, based on the static-analytic method. The pressure range under investigation was between 0.58 and 14.02 MPa. The Soave–Redlich–Kwong (SRK)-EOS coupled with Huron–Vidal (HV) mixing rules and a reduced UNIQUAC model, was used in a semi-predictive approach, in order to represent the complex phase behavior (critical curve, LLV line, isothermal VLE, LLE, and VLLE) of the system. The topology of phase behavior is qualitatively correct predicted.     

Phase equilibria experiments and calculations for carbon dioxide + methanol binary system

Vapor-liquid equilibria (VLE) data for the carbon dioxide + methanol system was measured at 293.15, 298.15, 310.15, and 323.15 K. Phase behavior measurements were made in a high-pressure visual cell with variable volume, based on the static-analytic method. The pressure range under investigation was between 4.8 and 95.1 bar. The Soave-Redlich-Kwong (SRK)-EOS coupled with Huron-Vidal (HV) mixing rules and a reduced UNIQUAC model, was used in a semi-predictive approach, in order to represent the phase behavior (critical curve, isothermal VLE) of the system. The topology of the phase behavior of the carbon dioxide + methanol system is satisfactory predicted with the SRK/HV-residual UNIQUAC model.      

High-pressure vapor–liquid equilibria for CO2 + alkanol systems and densities of n-dodecane and n-tridecane

An apparatus based on the static-analytic method was used to measure the vapor–liquid equilibria (VLE) for CO₂ + alkanol systems. Equilibrium measurements for the CO₂ + 1-propanol system were performed from 344 to 426 K. For the case of the CO₂ + 2-propanol system, measurements were made from 334 to 443 K, and for the CO₂ + 1-butanol were obtained from 354 to 430 K. VLE data were correlated with the Peng–Robinson equation of state using the classical and the Wong–Sandler mixing rules. Moreover, compressed liquid densities for the n-dodecane and n-tridecane were obtained via a vibrating tube densitometer at temperatures from 313 to 363 K and pressures up to 25 MPa. The Starling and Han (BWRS), and The five-parameter Modified Toscani-Swarcz (MTS) equations were used to correlate them. The experimental density data were compared with those from literature, and with the calculated values obtained from available equations for these n-alkanes.     

PVTx measurements for N2O + CH3F, N2O + CH2F2, and N2O + CHF3 binary systems

Isochoric PVTx measurements have been performed for the binary system of nitrous oxide + CH₃F (R41), +CH₂F₂ (R32), and +CHF₃ (R23) using a new experimental set-up. The experiments covered both the two-phase region and the superheated vapor region and were performed within the temperature range 214–358 K and within a pressure range from 270 to 5600 kPa. Data have been collected for not less than four compositions for each system. The vapor–liquid equilibrium data were derived correlating the experimental data by means of the Carnahan–Starling–De Santis equation of state. The studied systems show a positive deviation from the Raoult's law. The results obtained were compared with the Burnett PVTx data. The two methods showed a mutual consistency within an acceptable margin of error. No other experimental PVTx data were found in the literature for these binary systems.     

New high-pressures vapor-liquid equilibrium data for the carbon dioxide + 2-methyl-1-propanol (isobutanol) binary system

New vapor-liquid equilibria (VLE) data at 333.15, 343.15, and 353.15 K and pressures up to 130.0 bar are reported for the carbon dioxide + 2-methyl-1-propanol (isobutanol) system. The experimental method used in this work was a static analytical method with liquid and vapor phases sampling using a rapid online sampler injector (ROLSITM) coupled to a gas chromatograph (GC) for analysis. Measured VLE data and literature data for carbon dioxide + 2-methyl-1-propanol system were modeled with the Soave-Redlich-Kwong (SRK) cubic equation of state with classical van der Waals (two-parameter conventional mixing rule, 2PCMR) mixing rules. A single set of interaction parameters that lead to a correct phase behavior was used in this work to model the new VLE data and critical points of the mixtures in a wide range of temperature and pressure. The SRK prediction results were compared to the new data measured in this study and to available literature data.

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High pressure phase equilibrium properties for ethane+1-butanol system at 313.15 K

Phase equilibria and saturated densities for ethane+1-butanol system at high pressures were measured using a static-circulation apparatus at 313.15 K. The experimental apparatus equipped with three Anton Paar DMA 512S vibrating tube density meters was previously developed for measuring vapor–liquid–liquid equilibrium (VLLE) at high pressures. Co-existing phase composition and saturated density of each phase can be measured by means of the apparatus with a maximum temperature and pressure of 400 K and 20 MPa, respectively. The present experimental results include vapor–liquid equilibria (VLE), liquid–liquid equilibria (LLE), and VLLE. The equilibrium composition and density of each phase were determined by gas chromatography and density measurements, respectively. The experimental data were correlated with various equations of state.     

New p–ρ–T measurements up to 70 MPa for the system CO2 + propane between 298 and 343 K at near critical compositions

The vibrating tube densimeter method along with the Forced Path Mechanical Calibration model, is used to measure the high pressure isothermal p–ρ behavior of the CO₂+propane system along 17 isotherms between 293 and 343 K, at pressures up to 70 MPa. The compositions cover the range of mole fractions from x_CO2=0.45 to 1.0. The uncertainty in temperatures is ±0.015 K. The uncertainties in pressures are ±0.0013 MPa from 0.1 to 15.0 MPa and ±0.010 MPa from 5.0 to 70.0 MPa. The precision of the density measurements is ±0.014 kg m⁻³. The minimum global uncertainty is ±0.204 kg m⁻³, based on the calibration of the densimeter with pure water. A generalized Helmholtz energy model for mixtures is used to check the consistency of the new data with respect to previous p–ρ–T studies of this mixture. The average absolute deviation of our data with respect to the model is 0.64% which is fully consistent with the assessed accuracy.     

High-pressure phase equilibrium in the {carbon dioxide (1) + 1-chloropropane (2)} binary system

The current study reports original vapour-liquid equilibrium (VLE) for the system {CO₂ (1) + 1-chloropropane (2)}. The measurements have been performed over the entire pressure-composition range for the T = (303.15, 313.15 and 328.15) K isotherms. The values obtained have been used for comparison of four predictive approaches, namely the equation of state (EoS) of Peng and Robinson (PR), the Soave modification of Benedict–Webb–Rubin (SBWR) EoS, the Critical Point-based Revised Perturbed-Chain Association Fluid Theory (CP-PC-SAFT) EoS, and the Conductor-like Screening Model for Real Solvents (COSMO-RS). It has been demonstrated that the three EoS under consideration yield similar and qualitatively accurate predictions of VLE, which is not the case for the COSMO-RS model examined. Although CP-PC-SAFT EoS exhibits only minor superiority in comparison with PR and SBWR EoS in predicting VLE in the system under consideration, its relative complexity can be justified when taking into account the entire thermodynamic phase space and, in particular, considering the liquid densities and sound velocities over a wider pressure-volume-temperature range.     

New high-pressures vapor-liquid equilibrium data for the carbon dioxide + 2-methyl-2-propanol binary system

New vapor-liquid equilibria (VLE) data at 323.15, 333.15, 343.15, and 353.15 K and pressures up to 112.9 bar are reported for the carbon dioxide + 2-methyl-2-propanol system. The experimental method used in this work was a static analytical method with liquid and vapor phases sampling using a rapid online sampler injector (ROLSI?) coupled to a gas chromatograph (GC) for analysis. Measured VLE data and literature data for carbon dioxide + 2-methyl-2-propanol system were modeled with the Soave-Redlich-Kwong (SRK) cubic equation of state with classical van der Waals (two-parameter conventional mixing rule, 2PCMR) mixing rules. A single set of interaction parameters that lead to a correct phase behavior was used in this work to model the new VLE data and critical points of the mixtures in a wide range of temperature and pressure. The SRK prediction results were compared to the new data measured in this study and to available literature data.

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Vapor–liquid equilibria and excess molar volumes of diethylamine(1) + acetone(2) and diethylamine(1) + acetonitrile(2) binary systems

Isothermal vapor–liquid equilibrium (VLE) data for diethylamine(1)+acetone(2) and diethylamine(1)+acetonitrile(2) binary systems were obtained at 323.15 K by dynamic method. Excess molar volumes at 298.15 K for these systems were measured by a dilution dilatometer. VLE data have been checked for thermodynamic consistency and correlated by Wilson, NRTL and UNIQUAC equations. UNIFAC group interaction parameters for CH₂NH---CH₃CO and CH₂NH---CH₃CN pairs are also obtained from the experimental VLE data.     

Vapor-liquid equilibria for benzyl alcohol with carbon dioxide, ethane, or nitrogen at elevated pressures

Vapor-liquid equilibrium (VLE) phase compositions were measured for the binary systems of benzyl alcohol with carbon dioxide, ethane, or nitrogen at temperatures from 333.15 K to 453.15 K and pressures up to 19 MPa. Henry's constants were calculated from the isothermal equilibrium data. The new VLE data were correlated by the Patel-Teja equations of state with three different types of mixing rules. In general, using the one-fluid, two-parameter van der Waals mixing rule yielded the best representation for the investigated systems. The validity of a generalized Soave model was also tested with the equilibrium data of carbon dioxide + benzyl alcohol.     

Isothermal vapor–liquid equilibria and excess molar volumes for 2-methyl pyrazine (2MP) containing binary mixtures

2-Methyl pyrazine (2MP) has led to significant interest for its industrial and pharmaceutical uses. The new vapor–liquid equilibria (VLE) at 353.15 K and excess molar volumes (V^E) at 298.15 K over the whole mole fraction range for seven binaries (water, n-hexane, cyclohexane, n-heptane, methylcyclopentane (MCP), methylcyclohexane (MCH) and ethyl acetate (EA) with 2MP) have been measured. VLE were measured by using headspace gas chromatography and V^E were determined using precision density meter. The water+2MP system has only the minimum boiling azeotrope. The experimental VLE and V^E data were well correlated in terms of common g^E models and Redlich–Kister equation, respectively.     

Vapour–liquid equilibria, azeotropic data, excess enthalpies, activity coefficients at infinite dilution and solid–liquid equilibria for binary alcohol–ketone systems

Isothermal vapour–liquid equilibria (VLE), solid–liquid equilibria and excess enthalpies have been measured for the systems cyclohexanone + cyclohexanol and 2-octanone + 1-hexanol. Additionally in this paper binary azeotropic data at different pressures for 1-pentanol + 2-heptanone and 1-hexanol + 2-octanone have been determined with the help of a wire band column. Furthermore activity coefficients at infinite dilution for methanol, ethanol, 1-butanol and 1-propanol in 2-octanone at different temperatures have been measured with the help of the dilutor technique. These data together with literature data for alcohol–ketone systems were used to fit temperature-dependent group interaction parameters for the group contribution method modified UNIFAC (Dortmund) and the group contribution equation of state VTPR.     

Isobaric vapour–liquid equilibria data for the binary system 1-propanol+1-pentanol and isobaric vapour–liquid–liquid equilibria data for the ternary system water+1-propanol+1-pentanol at 101.3 kPa

Consistent vapour–liquid equilibrium (VLE) data for the binary system 1-propanol+1-pentanol and for the ternary system water+1-propanol+1-pentanol are reported at 101.3 kPa. An instrument using ultrasound to promote the emulsification of the partly miscible liquid phases have been used in the determination of the vapour–liquid–liquid equilibrium (VLLE). The VLE and VLLE data were correlated using UNIQUAC.     

New analytic apparatus for experimental determination of vapor–liquid equilibria and saturation densities

A new experimental apparatus for performing simultaneous determination of high-pressure vapor–liquid equilibria (VLE) and saturated densities was developed in this work. The experimental methodology was verified by measuring these properties for the carbon dioxide + 1-propanol and carbon dioxide + 2-propanol systems from 313 to 363 K. The apparatus is based on the static-analytic method for VLE determinations and was slightly modified by coupling a vibrating U-tube densitometer to obtain saturated densities for both vapor and liquid phases. VLE measurements agreed with previous literature data and were correlated with the Peng–Robinson equation of state coupled to the Wong–Sandler mixing rules. Saturation densities at temperatures above 313 K have not been published up to now.     

Thermodynamic properties of the system NH4NO3 + (NH4)2SO4 + H2O at 298.15 K

In this investigation, the mixed aqueous electrolyte system of nitrate and sulfate with common ammonium cation has been studied with the hygrometric method at the temperature 298.15 K. The water activities of the system [yNH₄NO₃ + (1 − y)(NH₄)₂SO₄](aq) are measured at total molalities from 0.4 mol kg⁻¹ up to saturation for different ionic-strength fractions y of NH₄NO₃ with y = 0.2, 0.5 and 0.8. The obtained data allow the deduction of osmotic coefficients. The experimental results are compared with the predictions of the Zdanovskii–Stokes–Robinson (ZSR), Leitzke and Stoughton (LSII), Kusik and Meissner (KM), and Pitzer models. From these measurements, new Pitzer mixing ionic parameters are determined and used to predict the solute activity coefficients in the mixture. The obtained results are used to calculate the excess Gibbs energy at total molalities for different ionic-strength fractions y.