Isobaric (vapour + liquid) equilibria for sulfolane with toluene, ethylbenzene, and isopropylbenzene at 101.33 kPa

Isobaric (vapour + liquid) equilibrium data have been measured for the (toluene + sulfolane), (ethylbenzene + sulfolane), and (isopropylbenzene + sulfolane) binary systems with a modified Rose-Williams still at 101.33 kPa. The experimental data of binary systems were well correlated by the non-random two-liquid (NRTL) and universal quasi-chemical (UNIQUAC) activity coefficient models for the liquid phase. All the experimental results passed the thermodynamic consistency test by the Herington method. Furthermore, the model UNIFAC (Do) group contribution method was used. Sulfolane is treated as a group (TMS), the new group interaction parameters for CH₂–TMS, ACH–TMS and ACCH₂–TMS were regressed from the VLE data of (toluene + sulfolane) and (ethylbenzene + sulfolane) binary systems. Then these group interaction parameters were used to estimate phase equilibrium data of the (isopropylbenzene + sulfolane) binary system. The results showed that the estimated data were in good agreement with the experimental values. The maximum and average absolute deviations of the temperature were 4.50 K and 2.39 K, respectively. The maximum and average absolute deviations for the vapour phase compositions of isopropylbenzene were 0.0237 and 0.0137, respectively.     

Vapor–liquid equilibria and excess volumes of the binary systems ethanol + ethyl lactate, isopropanol + isopropyl lactate and n-butanol + n-butyl lactate at 101.325 kPa

Isobaric vapor–liquid equilibrium data have been experimentally determined at 101.3 kPa for the binary systems ethanol + ethyl lactate, isopropanol + isopropyl lactate and n-butanol + n-butyl lactate. No azeotrope was found in any of the systems. All the experimental data reported were thermodynamically consistent according to the point-to-point method of Fredenslund. The activity coefficients were correlated with the NRTL and UNIQUAC liquid-phase equations and the corresponding binary interaction parameters are reported. The densities and derived excess volumes for the three mixtures are also reported at 298.15 K.     

Interaction parameters for multi-component aromatic extraction with sulfolane

Aromatic extraction is an important operation in petrochemical processing. Design of an aromatic extractor requires the knowledge of multi-component liquid–liquid equilibrium (LLE) data. Such experimental LLE data are usually not available and therefore can be predicted using various activity coefficient models. These models require proper binary interaction parameters, which are not yet available for all aromatic extraction systems. Furthermore, the parameters available for most of the ternary systems are specific to that system only and cannot be used for other ternary or multi-component systems. An attempt has been made to obtain these parameters that are globally applicable. For this purpose, the parameter estimation procedure has been modified to estimate the parameters simultaneously for different systems involving common pairs. UINQUAC and UNIFAC models have been used for parameter estimation. The regressed parameters are shown to be applicable for the ternary as well as for the multi-component systems. It is observed that UNIQUAC parameters provide a better fit for ternary LLE data, whereas, as one moves towards the higher component systems (quaternary and quinary) the UNIFAC parameters, which are a measure of the group contributions, predict the LLE better. Effect of temperature on UNIQUAC binary interaction parameters has been studied and a linear dependence has been observed.     

Retention parameters of aromatic hydrocarbons with mono-substituted polar groups in binary RP-HPLC systems

Summary Capacity factor (k′) values of aromatic hydrocarbons with mono-substituted polar-groups are correlated for reversed-phase systems involving stationary phases with C₁₈ or C₄ ligands chemically bonded to silica and a binary aqueous eluent containing modifiers: methanol, acetonitrile, tetrahydrofuran, isopropanol, dioxane or dimethoxyethane. The relative retention variations of the solutes are interpreted with special consideration of their interactions with non-polar stationary phases and the molecular structure of the modifiers and solutes. Rules for retention and selectivity optimisation in RP-HPLC systems are given.     

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.     

Phase equilibria and excess properties for binary systems in reactive distillation processes Part I. Methyl acetate synthesis

Isothermal vapor–liquid equilibrium (VLE) and excess enthalpy (H^E) data were measured for binary systems required for the design of reactive distillation processes for the methyl acetate production. The isothermal P–x data were measured with the help of a computer-operated static apparatus. A commercial isothermal flow calorimeter was used for the determination of the heats of mixing. Temperature-dependent interaction parameters for the UNIQUAC model were fitted simultaneously to the experimental data from this work and other authors.     

Isobaric vapor–liquid equilibria for the system 1-pentanol–1-propanol–water at 101.3 kPa

Consistent vapor–liquid equilibrium data for the ternary system 1-pentanol–1-propanol–water is reported at 101.3 kPa at temperatures in the range of 362–393 K. The VLE data were satisfactorily correlated with UNIQUAC model.     

Liquid–liquid equilibria for quaternary mixtures of nonane + undecane + (benzene or toluene or m-xylene) + sulfolane at 298.15 and 313.15 K

Liquid–liquid equilibrium (LLE) data were measured for three quaternary systems containing sulfolane, nonane + undecane + benzene + sulfolane, nonane + undecane + toluene + sulfolane and nonane + undecane + m-xylene + sulfolane, at T = 298.15 and 313.15 K and ambient pressure. The experimental quaternary liquid–liquid equilibrium data have been satisfactorily represented by using NRTL and UNIFAC-LLE models for the activity coefficient. The calculated compositions based on the NRTL model were found to in a better agreement with the experiment than those based on the UNIFAC-LLE model.     

Revision of the volumetric method for measurements of liquid–liquid equilibria in binary systems

A theoretical analysis of the accuracy of the volumetric method for the determination of liquid–liquid equilibrium was carried out. The results show that, under certain conditions, this method can be used to investigate systems showing relatively small mutual solubilities. Relations were derived to estimate standard deviations of the equilibrium compositions determined by the volumetric method.

In the experimental part of the work, an apparatus for measurements of mutual solubilities of liquids was constructed. A procedure that enabled us to determine precisely volumes of liquid phases was developed. This procedure and apparatus present the advantage that relatively small amounts of samples are required (approximately 2 × 20 ml). Theoretical conclusions concerning the applicability of the volumetric method were checked by measuring mutual solubilities at 303.15 K in systems methylcyclohexane + N,N-dimethylformamide, 1-butanol + water and dimethyl phthalate + water. Further, the method was used to measure systematically the liquid–liquid equilibrium in systems ethyl acetate + ethylene glycol and phenyl acetate + ethylene glycol at temperatures from 293 to 323 K. Data for these systems were acquired by means of other methods as well and a good agreement was observed on comparison.     

Viscometric and volumetric behaviour of binary mixtures of sulfolane and N-methylpyrrolidone with monoethanolamine and diethanolamine in the range 303–373 K

Capillary viscometry was used to determine the kinematic viscosity of the binary systems composed of N-methylpyrrolidone + monoethanolamine and N-methylpyrrolidone + diethanolamine throughout the concentration range, at eight different temperatures in the range 303.15–373.15 K. Pure component values of viscosity were also determined in the temperature range 303.15–423.15 K. Using a rolling ball viscometer the absolute viscosity was obtained for the binary systems composed of tetramethylene sulfone (sulfolane) + monoethanolamine and tetramethylene sulfone + diethanolamine, throughout the concentration range, at three different temperatures in the range 303.15–373.15 K. Density results were obtained using a vibrating-tube densimeter for the four pure components and the four binary systems studied, in the same temperature range and the whole concentration range for the binary systems as the viscosity measurements.

The experimental viscosity results for the four pure solvents cover a broader temperature range than previously reported by other workers. The experimental results of viscosity for both pure and binary systems show a decrease with increasing temperature as expected. In the case of the binary systems the change of viscosity with concentration for the two sets of mixtures with N-methylpyrrolidone is very large in the range of 303.15–353.15 K, whereas it is small in the range 363.15–373.15 K. The observed behaviour of the change of viscosity with concentration for sulfolane with monoethanolamine is different from that shown by sulfolane with diethanolamine, at 303.15 and 323.15 K; the first system shows a minimum viscosity point in the sulfolane-rich region whereas at 373.15 K it shows values of viscosity greater than that of the pure components in the whole range of concentration; and the second system shows large variations of viscosity at low sulfolane concentration, at 303.15 and 323.15 K; whereas at 373.15 K the viscosity values change smoothly between those for the two pure components.

From the density results, molar excess volumes were derived, which were correlated using the Redlich–Kister equation; the final expression includes the functionality with both concentration and temperature.     

Isobaric vapor–liquid equilibria for acetone + methanol + lithium nitrate at 100 kPa

Isobaric vapor–liquid equilibria for the ternary system acetone + methanol + lithium nitrate have been measured at 100 kPa using a recirculating still. The addition of lithium nitrate to the solvent mixture produced an important salting-out effect and the azeotrope tended to disappear for small contents of salt. The experimental data sets were fitted with the electrolyte NRTL model and the parameters of the Mock's model were estimated. These parameters were used to predict the ternary vapor–liquid equilibrium which agreed well with the experimental one.     

Phase equilibria on five binary systems containing 1-butanethiol and 3-methylthiophene in hydrocarbons

Isothermal vapor–liquid equilibrium (VLE) of the following systems was measured with a recirculation still: 1-butanethiol + methylcyclopentane at 343.15 K, 1-butanethiol + 2,2,4-trimethylpentane at 368.15 K, 3-methylthiophene + toluene at 383.15 K, 3-methylthiophene + o-xylene at 383.15 K, and 3-methylthiophene + 1,2,4-trimethylbenzene at 383.15 K. 1-Butanethiol + methylcyclopentane and 1-butanethiol + 2,2,4-trimethylpentane systems exhibit positive deviation from Raoult's law, whereas systems containing 3-methylthiophene in aromatic hydrocarbons exhibit only slight positive deviation from Raoult's law. A maximum pressure azeotrope was found in the system 1-butanethiol + 2,2,4-trimethylpentane (x₁ = 0.548, P = 100.65 kPa, T = 368.15 K). The experimental results were correlated with the Wilson model and compared with original UNIFAC and COSMO-SAC predictive models. Raoult's law can be used to describe the behavior of 3-methylthiophene in aromatic hydrocarbons at the experimental conditions in this work. Liquid and vapor-phase composition were determined with gas chromatography. All measured data sets passed the thermodynamic consistency tests applied. The activity coefficients at infinite dilution are also presented.     

Estimation of boiling points by investigations of viscosity Arrhenius behaviours in Methyl Benzoate + n-Hexane binary liquid systems at atmospheric pressure

Calculation of excess properties in methyl benzoate + n-Hexane binary liquid mixtures at (303.15, 308.15 and 313.15) K from experimental viscosity and density values was presented in earlier work. Investigations of these experimental values to test correlation quality of different equations as well as their corresponding relative functions were also reported. Considering the quasi-equality between the enthalpy of activation of viscous flow ΔH* and the viscosity Arrhenius activation energy Ea, here we can define partial molar activation energy Ea₁ and Ea₂ for methyl benzoate with n-Hexane, respectively, along with their individual contribution separately. Correlation between Arrhenius parameters brings to light interesting Arrhenius temperature with a comparison to the temperature of vaporisation in the liquid vapour equilibrium, and the limiting corresponding partial molar properties that can permit us to predict value of the boiling points of the pure components. New empirical equations for estimating the boiling temperature are proposed.     

Solid–liquid equilibria based on an equation of state for chain fluids

Solid–liquid equilibria were studied using an equation of state previously developed for fluids containing chain-like molecules. The method was used to correlate solubilities of normal alkanes and aromatic compounds with high molecular mass in hydrocarbon solvents. With one temperature independent parameter for the interaction energy, good agreement can be obtained between calculated results and experimental data for selected systems.     

Isobaric vapour–liquid equilibria for binary systems of 2-butanone with ethanol, 1-propanol, and 2-propanol at 20 and 101.3 kPa

Consistent isobaric vapour–liquid equilibrium data have been measured for 2-butanone + ethanol, 2-butanone + 1-propanol, and 2-butanone + 2-propanol at 20 and 101.3 kPa. The binary systems 2-butanone + ethanol and 2-butanone + 2-propanol present a minimum boiling azeotrope at both pressures, and show that the azeotropic compositions is strongly dependent on pressure. The equilibrium data were correlated using the Wilson, NRTL, and UNIQUAC models for which the parameters are reported.     

Prediction of the bubble point pressure for the binary mixture of ethanol and 1,1,1,2,3,3,3-heptafluoropropane from Gibbs ensemble Monte Carlo simulations using the TraPPE force field

Configurational-bias Monte Carlo simulations in the Gibbs ensemble using the TraPPE force field were carried out to predict the pressure–composition diagrams for the binary mixture of ethanol and 1,1,1,2,3,3,3-heptafluoropropane at 283.17 and 343.13 K. A new approach is introduced that allows one to scale predictions at one temperature based on the differences in Gibbs free energies of transfer between experiment and simulation obtained at another temperature. A detailed analysis of the molecular structure and hydrogen bonding for this fluid mixture is provided.     

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.     

多环芳烃水中溶解度的理论计算

建立了计算多环芳烃水中溶解度的数学表达式，用量子化学方法计算了7个多环芳烃的水中溶解度，计算结果与实验测定结果相符合．多环芳烃处于水体内体系状态能量愈高，其溶解度愈小，多环芳烃中的碳氢基团越多，溶解度越小．此时体系中的溶质呈单分子态，而不是聚集态．     

Vapor pressure of R227ea + ethanol at 343.13 K by molecular simulation

A new molecular model for 1,1,1,2,3,3,3-heptafluoropropane (R227ea) was developed on the basis of quantum chemical calculations and optimized using experimental vapor pressure and bubble density data. In combination with an existing model for ethanol, a molecular model for the binary mixture R227ea + ethanol was defined, using the Lorentz–Berthelot combining rule. It was validated at 283.17 K, where, considering the statistical uncertainties, it agrees to the experimental vapor pressure. The vapor–liquid equilibrium, comprising both bubble line and dew line data, was predicted at 343.13 K by molecular simulation. The Peng–Robinson equation of state fails for this system.