Vapor-liquid equilibrium in selected aromatic binary systems: m-xylene-hydrogen sulfide and mesitylene-hydrogen sulfide

Huang, S.S.-S. and Robinson, D.B., 1984. Vapor—liquid equilibrium in selected aromatic binary systems: m-xylene—hydrogen sulfide and mesitylene—hydrogen sulfide. Fluid Phase Equilibria, 17: 373–382.Vapor and liquid equilibrium phase compositions have been determined for the m-xylene-hydrogen sulfide and mesitylene—hydrogen sulfide binary systems at temperatures of 310.9, 352.6, 394.3 and 477.6 K and at several pressures from the vapor pressure of the less volatile component to the vapor pressure of hydrogen sulfide or to the critical pressure for the system, whichever was higher. The data have been used to calculate equilibrium ratios for each of the components in the binary systems. The results of Eakin and DeVaney (1974) for the mesitylene—hydrogen sulfide system at 310.9 and 477.6 K are also included for comparison.The data presented are useful in evaluating the properties of condensate reservoir fluids containing hydrogen sulfide and aromatic compounds.     

Study on volatility and flash point of the pseudo binary mixtures of sunflower-based biodiesel + methylcyclohexane

The transesterification of sunflower seed oil was carried out in supercritical ethanol without using any catalyst to produce biodiesel. In the present work, methylcyclohexane was added to enhance the vapor pressure of biodiesel. The vapor pressures of mixtures of biodiesel + methylcyclohexane as a function of temperature were measured by comparative ebulliometry with an inclined ebulliometer. The vapor pressures versus composition at different temperatures were obtained. Experimental data of vapor pressures and equilibrium temperatures were correlated by the Antoine equation. A mathematical model was used to predict the flash point of the pseudo binary mixtures. With the regular solution theory, the predictive flash point displays agreement with the experimental data obtained by closed cup test.     

The prediction of isobaric phase equilibria for non-ideal multicomponent mixtures from heat of mixing data

A method for predicting isobaric binary and ternary vapor—liquid equilibrium data using only isothermal binary heat of mixing data and pure component vapor pressure data is presented. Three binary and two ternary hydrocarbon liquid mixtures were studied. The method consists of evaluating the parameters of the NRTL equation from isothermal heat of mixing data for the constituent binary pairs. These parameters are then used in the multicomponent NRTL equation to compute isobaric vapor—liquid equilibrium data for the ternary mixture. No ternary or higher order interaction terms are needed in the ternary calculations because of the nature of the NRTL equation. NRTL parameters derived from heat of mixing data at one temperature can be used to predict vapor—liquid equilibrium data at other temperatures up to the boiling temperature of the liquid mixture.For the systems studied this method predicted the composition of the vapor phase with a standard deviation ranging from 1–8% for the binary systems and from 4–12% for the ternary systems.     

Vapor—liquid equilibria for the binary system 2-methylbutene-2 and 2-methyl-1,3-butadiene at 310.93, 316.48 and 322.04 K

Total pressure, vapor—liquid equilibrium data for the binary system 2-methyl-1,3-butadiene and 2-methylbutene-2 are reported at 310.93, 316.48 and 322.04 K. The experimental uncertainties in measured variables, expressed as standard deviations, are 0.0005 mole fraction, 0.01 K and 0.2% of measured pressure. The coefficients for a modified Wilson solution model are also reported. These coefficients were determined from the experimental data using a general non-linear least-squares technique which accounts for experimental uncertainties in independent and dependent variables. The standard deviations of prediction for temperature-independent coefficients are 0.17% for pressure, 0.001 K for temperature and 0.00001 for mole fraction.     

Vapor—liquid equilibria of the ternary system CF4CHF3CClF3 at 199.80 K and 3.447 and 6.895 bars

The vapor and liquid phase equilibrium compositions of the ternary system CF₄CHF₃CClF₃ were measured under isothermal and isobaric conditions of 199.80 K and 3.447 and 6.895 bars, respectively, using a vapor-recirculation apparatus. In accordance with the vapor phase being described by a modified Redlich—Kwong equation of state, liquid-phase activity coefficients were calculated and compared with the values predicted by the Wilson equation from available parameters for the three binary systems. Good agreement was found. The correlation developed allows calculation of the equilibrium compositions at 199.80 K and any pressure between 1.544 and 15.272 bars.     

Vapor-liquid equilibria for the nitrogen-isobutane system

Vapor-liquid equilibria have been investigated experimentally for the nitrogen-isobutane system at temperatures from 120 K to 220 K and at pressures up to 150 bar. Below 126.5 K, two liquid phases were observed as pressure was increased to near the vapor pressure of pure nitrogen. The equilibrium ratio of nitrogen in the binary system and the Henry’s law constants for nitrogen in isobutane were determined from experimental data. The experimental phase equilibrium data were correlated by means of the Peng-Robinson equation of state.     

Vapor–liquid equilibrium data and critical points for the system H2S+COS. Extension of the PSRK group contribution equation of state

Isothermal vapor–liquid equilibrium data for the binary system hydrogen sulfide+carbonyl sulfide were measured in the temperature range from 232 to 293 K using the static-synthetic technique. From the isothermal P−x data, the azeotropic conditions were derived. The critical line of this system was visually detected in a flow apparatus. Interaction parameters for this binary system were fitted simultaneously to all the experimental VLE and critical data for the Predictive Soave–Redlich–Kwong group contribution equation of state.     

Ternary liquid—liquid equilibria for acetonitrile—ethanol—cyclohexane and acetonitrile—2-propanol—cyclohexane

Liquid—liquid equilibrium data were obtained for two ternary systems: acetonitrile— ethanol—cyclohexane at 40°C, and acetonitrile—2-propanol—cyclohexane at 50°C. Binary vapor—Liquid equilibrium data were measured for acetonitrile—2-propanol at 50°C. The binary parameters of the Zeta and effective Zeta equations were evaluated from equilibrium data for binary pairs. The parameters obtained were used to predict the ternary liquid—liquid equilibrium data for six systems involving the present systems and the ternary vapor—liquid equilibrium data for one completely miscible system and two partially miscible systems without adding any ternary parameter. A heterogeneous area calculated by the Zeta equation is in general too large and does not decrease appreciably with increasing values of the third parameter ζ of the Zeta equation. However, the effective Zeta equation works much better than the original Zeta equation in data reduction.     

Development of a new apparatus for gas mixture adsorption measurements coupling gravimetric and chromatographic techniques

An experimental apparatus which allows to measure adsorption isotherms for binary, ternary or quaternary mixtures for pressures between vacuum and 5.0 MPa and temperatures between 263 K and 373 K is presented. This system couples gravimetric and chromatographic techniques. The use of a mass spectrometer as gas analyzer allows to investigate a large variety of gases (such as carbon dioxide, hydrogen sulfide, mercaptans). In this paper, we measure the binary adsorption of hydrogen sulfide in a methane matrix on a commercial activated carbon at 1.0 MPa and at 298 K. Molar ratio in hydrogen sulfide is between 10 mol. ppm and 3 mol.%. Experimental results are then compared to simulated ones. The model which is tested is the classical Ideal Adsorbed Solution theory. This simulation step requires the pure gas equilibrium data obtained and fitted with the Langmuir’s law, which are also presented here.     

The prediction of isothermal phase equilibria for non-ideal multicomponent mixtures from heats of mixing

A method is presented for predicting both vapor—liquid and liquid—liquid equilibria for multicomponent mixtures using heat of mixing data for the constituent binary pairs together with pure component vapor pressures. Its application to two highly non-ideal hydrocarbon ternary systems is discussed. The parameters of the hybrid local composition model of Renon and Prausnitz, known as the NRTL equation, were evaluated from heat of mixing data for the three binary pairs in each of the two ternary systems. The parameters thus obtained were used in the multicomponent form of the NRTL equation to predict the ternary vapor—liquid equilibrium data for the completely miscible system cyclohexane(1)—n-heptane(2)—touluene(3) and for the partially miscible system acetonitrile(1)—benzene(2)—n-heptane(3) without the need for any ternary or higher order parameters.This method predicted compositions of the single phase region of the partially miscible ternary system with a standard deviation of 10%. It also predicted compositions for the fully miscible system with a standard deviation of 4.6%. Total pressure curves for the partially miscible and miscible ternaries were predicted with standard deviations of 6.6% and 4.5% respectively. Poor predictions of the binodal curve for the partially miscible region were obtained. The method offers a means of predicting the whole range of ternary phase equilibria for miscible systems.     

Vapor—liquid equilibrium in ternary mixtures of hydrogen + carbon dioxide + 1-methylnaphthalene

Compositions of saturated vapor and liquid phases at equilibrium were measured for hydrogen + carbon dioxide + 1-methylnaphthalene mixtures at 543 and 704 K over a pressure range of 50–250 atm. Measurements were made at three relative concentrations of hydrogen to carbon dioxide at each condition of temperature and pressure. A significant variation of the K-value of 1-methylnaphthalene with gas composition was observed in the high pressure region.     

氯仿－苯－正丁醇三元体系加压相平衡研究

本文根据氯仿、苯、正丁醇有关二元体系实测数据统一关联所得的能量参数关联式，用Ｗｉｌｓｏｎ方程对氯仿－苯－正丁醇三元体系在１０１～３０３ｋＰａ压力下的汽液平衡作了预测，并与本工作的实测数据比较，二者符合良好。实验结果表明，这三元体系与氯仿－苯－乙醇体系的汽液相平衡行为具有相似的规律。     

Effect of hydrogen bonding on the intramolecular charge transfer fluorescence of 6-dodecanoyl-2-dimethylaminonaphtalene

The effect of hydrogen bonding on the intramolecular charge transfer (ICT) of 6-dodecanoyl-2-dimethylaminonaphtalene (laurdan) in neat and binary solvent mixtures has been investigated by using steady-state and time-resolved spectroscopic techniques. The different features of ICT emission of laurdan in methylcyclohexane–tetrahydrofuran and methylcyclohexane–ethanol are explained by the absence and presence of hydrogen bonded ICT. The presence of isosbestic point in absorption spectra of laurdan in methylcyclohexane–ethanol confirms the formation of 1:1 complex between laurdan and ethanol. The obtained data were used to determine the stoichiometric equilibrium constants. In protic rigid (77 K) the fluorescence spectra of laurdan show excitation wavelength dependence (the red-edge effect). Moreover, we reported the decay characteristics of laurdan molecule in locally excited (LE) and ICT state in methylcyclohexane–ethanol.     

Frequency response study of the dynamics of the platinum catalyzed interconversion of methylcyclohexane, toluene, and hydrogen near equilibrium

The dynamics of the platinum catalyzed interconversion of methylcyclohexane, toluene, and hydrogen near equilibrium were investigated in a closed reactor system by a frequency response method at temperatures in the range of 433 to 473 K and at total pressures in the vicinity of 80 to 110 Torr. The gas phase in contact with the platinum catalyst was always hydrogen-rich, with hydrogen to hydrocarbon mole ratios maintained in the range of 3.2 to 4.6. The frequency response method utilized small perturbations (lower than 1%) of the volume of the system, with measurements of the total pressure being used to determine the response of the system. The range of perturbation frequencies investigated was approximately 0.002 to 3 Hz (0.013 to 19 rad s(-1)). The experiments revealed two characteristic relaxation frequencies that are associated with the dynamics of the interconversion. The dynamics of the system are interpreted in terms of a simple two-step interconversion sequence with the aid of a phenomenological frequency response theory formulated in terms of relaxation frequencies of the steps and equilibrium properties of the system. It is concluded that one of the steps, a toluene adsorption-desorption step, is much slower than the other, a step involving the interconversion of the gas-phase methylcyclohexane and chemisorbed toluene that releases or consumes hydrogen in the process.     

Vapor-phase chemical equilibrium for the hydrogenation of benzene to cyclohexane from reaction-ensemble molecular simulation

The reaction-ensemble Monte-Carlo (REMC) molecular simulation method was used to study the vapor-phase chemical equilibrium for the reaction of hydrogenation of benzene to cyclohexane. A one-center modified Buckingham exponential-6 (1CMBE6) effective pair potential model (that had already been used to predict thermodynamic properties and liquid–liquid equilibria of helium+hydrogen mixtures) was used for hydrogen. Six-center modified Buckingham exponential-6 (6CMBE6) effective pair potential models (that had already been used to reproduce the saturated liquid and vapor densities, vapor pressures, second virial coefficients, and critical parameters of the six-membered ring molecules), were used for benzene and cyclohexane. No binary adjustable parameters were needed to compute the unlike-pair Buckingham exponential-6 interactions in the ternary system. Simulation results were obtained for the effect of some operating variables such as temperature (from 500 to 650 K), pressure (from 1 to 30 bar), and hydrogen to benzene feed mole ratio (from 1.5:1 to 6:1) on the reaction conversion, molar composition, and mass density of the ternary system at equilibrium. These results were found to be in excellent agreement with calculations using the predictive Soave–Redlich–Kwong (PSRK) group contribution equation of state.     

Isothermal vapor—liquid equilibrium of ternary mixtures formed by 1-propanol,acetonitrile and benzene

Vapor—liquid equilibrium data are presented for the ternary system 1-propanol-acetonitrile-benzene, at 45°C. The experimental vapor—liquid equilibrium results of the three constituent binary systems are well reproduced with the UNIQUAC associated-solution model and the ternary results are compared with those calculated from the model with binary parameters alone. Ternary prediction of liquid—liquid equilibria is given for the 1-propanol-acetonitrile-n-hexane and 1-propanol—acetonitrile-n-heptane systems at 25°C.     

氯仿,乙醇,苯有关二元体系加压相平衡研究

氯仿、乙醇、苯有关二元体系加压相平衡研究马忠明，陈庚华，王琦，严新焕，韩世钧，余淑娴（浙江大学化学系，杭州，３１００２７）（江西大学化学系）关键词加压汽液平衡，醇烃体系，氯仿，乙醇，苯醇是极性分子，烃是非极性或弱极性分子，醇与醇、烃与烃分子及醇与烃分...     

Vapor pressures and flash points for binary mixtures of tricyclo [5.2.1.0] decane and dimethyl carbonate

Bubble-point vapor pressures, equilibrium temperatures and flash points for binary mixtures of a high energy density hydrocarbon fuel, tricyclo [5.2.1.0^2.6] decane (JP-10), and dimethyl carbonate (DMC) were measured. Correlation between vapor pressures and equilibrium temperatures for each mixture was given by the Antoine equation. The binary system of JP-10 and DMC appears with very large positive deviations of vapor pressure from the Raoult's law. The experimental vapor pressures are correlated and the flash points are then predicted using Scatchard-Hildeband, Van Laar and Wilson models of liquid phase activity coefficients with satisfactory results.     

Liquid—vapor equilibrium in the system H2Ar at temperatures from 83 to 141 K and pressures to 52 MPa

Calado, J.C.G. and Streett, W.B., 1979. Liquid—vapor equilibrium in the system H₂Ar at temperatures from 83 to 141 K and pressures to 52 MPa. Fluid Phase Equilibria, 2: 275–282.Experimental measurements of liquid—vapor phase equilibria in the system H₂Ar are reported for thirteen temperatures in the range 83.09 to 141.42 K, and pressures to 52 MPa. The mixture critical line and the pressure—temperature trace of the three-phase line solid—liquid—gas have been located. These lines intersect at T = 84.0 K and P = 52.5 MPa to form an upper critical end point. The pressure—temperature trace of the three-phase line has a temperature minimum at T ? 82.5 K, P ? 20 MPa.