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As there is an azeotropic point between methanol and ethyl formate, they cannot be completely separated by ordinary distillation. In this paper, extractive distillation was applied and dimethyl sul...

Methanol and methylal form a minimum boiling point azeotrope and cannot be separated by conventional distillation. In this paper, the azeotrope was separated by extractive distillation with cyclohe...

Ethyl propionate is usually produced from esterification of propionic acid and ethanol in the industry. However, the purification of ethyl propionate remains a challenge because the unreacted ethan...

Ionic liquids (ILs) have shown remarkable potential for applications in separation, such as extractive distillation and liquid–liquid extraction. Crucial to these applications is the estimation of ...

The mixture of water, methanol, and ethanol is frequently produced in the pharmaceutical industry. To separate the mixture by extractive distillation, the selection of entrainer is a crucial step. ...

Natural deep eutectic solvents (NADESs) are designer green solvents which share many properties with ionic liquids. The uncommon intermolecular adjustment in a NADES matrix shows exceptional solubilizing and stabilizing properties. These properties make them suitable to be used as an entrainer for extractive distillation. The present work investigates the synthesis of choline chloride-based NADES and its viability as an entrainer for separation of acetonitrile (ACN) + water mixture by extractive distillation. A NADES was prepared by employing two natural and biodegradable compounds, dl-malic acid and choline chloride in a 1:1 molar ratio (MC1:1). The vapor–liquid equilibria at isobaric condition were measured for pseudo-binary mixtures (water + MC1:1 and ACN + MC1:1) using an improved Othmer recirculation still at 101.3 kPa. Other than these, the vapor–liquid equilibrium data for ACN + water + MC1:1 pseudo-ternary mixture were also measured at different NADES concentrations. From the results, MC1:1 could ...

An organic salt choline chloride (ChCl) was introduced in ethylene glycol (EG) for improving the entrainer performance for ethanol dehydration by extractive distillation. The mixed solvent EG + ChC...

2,3-Pentanedione, acetaldehyde, and acetone are by-products found downstream in the sugar manufacturing process. 2,3-Pentanedione has various food and industrial-related uses, making it a product of interest. It can be recovered using extractive distillation recovery processes, whereby chemicals of similar boiling points are separated. Vapor–liquid equilibrium (VLE) measurements were conducted isobarically for the systems 2,3-pentanedione + {acetaldehyde or acetone} at 100, 150, and 200 kPa. Measurements were undertaken using a moderate pressure recirculating VLE still, capable of withstanding pressures up to 350 kPa. The measured VLE data were regressed using the gamma–phi (γ–φ) approach and the nonrandom two-liquid activity coefficient model, which displayed satisfactory representation of the system behavior. None of the binary systems exhibit azeotropic behavior. All the binary systems displayed a positive deviation from Raoult’s law.

For separation of the azeotrope (methanol + methyl acetate), extractive distillation is applied and isobutyl acetate, isopentyl acetate, and p-xylene are chosen as the entrainers. To obtain the binary interaction parameters of thermodynamic models for design of the extractive distillation process, the isobaric vapor–liquid equilibrium (VLE) data for the three binary systems of (methyl acetate + isobutyl acetate), (methyl acetate + isopentyl acetate), and (methyl acetate + p-xylene) were determined at the pressure of 101.3 kPa. The thermodynamic consistency for the VLE experimental data of the three mixtures were tested by the Herington and van Ness methods. The NRTL, UNIQUAC, and Wilson thermodynamic models were adopted to correlate the VLE experimental data, and the binary interaction parameters of the three models were regressed.

Low transition temperature mixtures (LTTMs) are versatile alternatives to ILs. They share many properties with ILs, so they become a suitable choice for entrainers in extractive distillation processes. In this study, glycolic acid and choline chloride in a 3:1 molar ratio (GC3:1) were synthesized and explored as entrainers for separation of acetonitrile + water azeotropic mixtures. Isobaric vapor–liquid equilibrium data for the pseudobinary mixtures of ACN + GC3:1 and water + GC3:1 were measured at atmospheric pressure (101.32 kPa). For the pseudoternary system ACN + water + GC3:1, also VLE data were measured at different GC3:1 mole fractions of 0.05, 0.1, and 0.15. The thermodynamic modeling of these systems was performed using the nonrandom two-liquid (NRTL) model. Furthermore, a study was conducted for synthesized GC3:1 recoverability. A good agreement were found between experimental data and predicted values for these systems. Results showed that LTTM (GC3:1) eliminated the acetonitrile + water azeotr...

The mixed solvent of ethylene glycol (EG) and choline chloride (ChCl) was tested as an entrainer for 2-propanol dehydration by extractive distillation. Isobaric vapor–liquid equilibrium (VLE) data were measured at 101.3 kPa for the quaternary system water + 2-propanol + EG + ChCl. The NRTL equation was used for the modeling of the quaternary VLE. Mean absolute deviations were 0.26 K and 0.0036 for equilibrium temperature and vapor mole fraction of 2-propanol, respectively. As compared with EG alone, the existence of ChCl in the solvent significantly decreases the activity coefficient of water and increases the activity coefficient of 2-propanol, both enhancing the relative volatility of 2-propanol to water. The azeotrope of water +2-propanol can be removed with the addition of the deep eutectic mixture EG + ChCl 2:1 at a solvent mass fraction of 0.157. The mixed solvent may be readily applied in extractive distillation of 2-propanol and water, replacing the frequently used mixed solvent of ethylene glycol...

In this work, ionic liquids (ILs) were selected as extractive distillation entrainers to separate the 2-butanone + ethanol binary azeotropic mixture because of their remarkable molecular designability, high selectivity, low volatility, and other excellent characteristics. The isobaric vapor–liquid equilibrium (VLE) data for the ternary systems of 2-butanone + ethanol + acetate-based ILs (1-ethyl-3-methylimidazolium acetate [EMIM][OAC], 1-butyl-3-methylimidazolium acetate [BMIM][OAC], and 1-hexyl-3-methylimidazolium acetate [HMIM][OAC]) were measured at 101.3 kPa in an all-glass dynamic recirculating still. The addition of ILs can significantly enhance relative volatility of 2-butanone to ethanol, and the azeotropy of the 2-butanone + ethanol binary mixture is eventually eliminated by increasing the IL content to a certain value. The separation efficiency of the three ILs follows the order [EMIM][OAC] > [BMIM][OAC] > [HMIM][OAC]. Additionally, the binary and ternary VLE data are well-correlated with the no...

Ethyl lactate, which is an expected renewable solvent, was tested as an entrainer candidate for the separation of the binary methanol + dimethyl carbonate (DMC) azeotropic system by extractive distillation. Isobaric vapor–liquid equilibria (VLE) for two binary constituent systems, that is, methanol + DMC and DMC + ethyl lactate of the methanol + DMC + ethyl lactate ternary system, were determined by an ebulliometric method at pressures of (40.00 to 101.3) kPa. The experimental VLE data were fitted by the nonrandom two-liquid (NRTL) model. Predictions of the binary systems were also performed by the NIST-modified universal functional activity coefficient (UNIFAC) group contribution model. The separation effects of ethyl lactate were examined by two methods: residue curve map and relative volality α12 using the binary NRTL parameters. Both sets of calculated results indicated that ethyl lactate can be used as entrainer. Compared to other entrainers reported in the previous works, ethyl lactate would be a mo...

Diethyl carbonate and methyl isobutyl ketone are tested as possible entrainers for separating 1-hexene and n-hexane by extractive distillation. For this purpose, isobaric vapor–liquid equilibrium (VLE) data at 100 kPa have been obtained for the two ternary systems formed by the two hydrocarbons and one of the selected solvents: 1-hexene + n-hexane + diethyl carbonate and 1-hexene + n-hexane + methyl isobutyl ketone. VLE data for the following constituent binary systems have also been determined: 1-hexene + diethyl carbonate, n-hexane + diethyl carbonate, 1-hexene + methyl isobutyl ketone, and finally n-hexane + methyl isobutyl ketone. All binary systems present moderate positive deviations from Raoult’s law, and neither binary systems nor ternary systems show an azeotrope. The local composition models Wilson, UNIQUAC, and NRTL have been used for correlating VLE data and evaluating solvent effects.

An important problem in the chemical industry is the separation of azeotropes. Their separation by simple distillation is basically impossible, and extractive distillation consumes much more energy than liquid–liquid extraction, so this alternative could be interesting. Recently, researchers have started to explore these option using ionic liquids as the solvent. The remarkable properties of ionic liquids have made them sustainable alternatives to conventional solvents. This work is a continuation of a study developed by our research group on the use of ionic liquids as extractant solvents of alcohol + water mixtures which form azeotropes, using in this case 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide ([bmp][Tf2N]) as an ionic liquid. The effect of temperature on the liquid–liquid equilibrium for the water + 1-propanol + [bmp][Tf2N] system was studied by determining the tie lines at different temperatures (283.2, 303.2, and 323.2 K) and atmospheric pressure. The NRTL and UNIQUAC models...

The reaction for hydrogenation of benzene has been paid much attention as the demand for synthesis of nylon rapid developa. Usually, byproducts of cyclohexane and unreacted benzene unavoidably exist in the production of cyclohexene through the hydrogenation of benzene route. To obtain cyclohexene with high purity, extractive distillation is used to separate cyclohexene mixture. However, the process simulation for extractive distillation is necessary for industry design and production, which requires the relevant vapor–liquid equilibrium (VLE) data to simulate accurately. The VLE data for the binary systems of extractant N,N-dimethylacetamide (DMAC) with cyclohexene, cyclohexane, and benzene at atmospheric pressure was measured using a PH-I-type VLE kettle. In addition, a thermodynamic consistency check has been done on the obtained data, indicating that the experimental data satisfy the examination of the thermodynamic consistencies. Moreover, the results are significantly close when NRTL and Wilson equat...

Isobaric vapor–liquid equilibrium (VLE) data for the tert-butyl alcohol (t-BuOH) + water + triethanolamine (TEA), t-BuOH + water + triethanolamine formic acid ([TEA][Fc]), t-BuOH + water + triethanolamine acetic acid ([TEA][Ac]), and t-BuOH + water + triethanolamine lactic acid ([TEA][Lc]) ternary systems were measured at 101.3 kPa. The results indicated that all the three ILs produced a more obvious effect on the VLE behavior of t-BuOH + water system than TEA, and eliminated the azeotropic point in the whole concentration range. [TEA][Lc] was the best solvent for the separation of the t-BuOH + water system by extractive distillation among the three ILs investigated. The experimental VLE data for the ternary systems were correlated with the NRTL model equation, and good correlations were obtained with an average relative deviation of 2.4 %.

The present work aims at establishing reliable activity coefficient model for vapor–liquid equilibrium (VLE) of the system water + ethanol + glycerol, with an emphasis on the application in ethanol dehydration by extractive distillation. New experimental data were reported for ternary VLE at 100 kPa, boiling temperature of water + glycerol at 101.33 kPa, and infinite dilution activity coefficient of water and ethanol, respectively, in glycerol at five temperatures of 313.15 K to 393.15 K. The NRTL equation was used for the modeling. For extending the composition and temperature range of data source, literature data of binary VLE of water + ethanol, infinite dilution activity coefficients of water + ethanol, and excess enthalpies of water + glycerol were also used for optimization of the NRTL parameters. The correlation showed that the azeotrope of water + ethanol can be removed at a glycerol mass fraction of 0.0902. The experimental results were compared graphically with those of calculations, showing goo...

Isobaric vapor–liquid equilibrium (VLE) data for the ternary system water + 2-propanol + glycerol are reported at 100 kPa. The ternary VLE data, together with literature values of binary VLE and activity coefficients at infinite dilution for water + 2-propanol, were correlated by the NRTL activity coefficient model. The correlation appears to be satisfactory for all the data. The experimental results were compared graphically with those of calculations, showing good agreement. With the addition of glycerol, the azeotrope of water + 2-propanol can be removed at a glycerol mass fraction of 0.229. Glycerol is a potentially effective entrainer for dehydration of 2-propanol by extractive distillation.

The unusual properties of 1-methyl-2-pyrrolidone or N-methyl-2-pyrrolidone (NMP) make it a solvent of interest in industrial extractive distillation processes. To augment available data, vapor–liquid equilibrium (VLE) measurements were made for NMP + 1-hexene at (313.15, 335.15, and 363.15) K, for NMP + water at (343.15, 363.15, and 380.15) K, and for NMP + 1-butanol at (10, 25, and 50) kPa using a dynamic recirculating apparatus. Limiting activity coefficients are reported for water and n-hexene as solutes in NMP. Activity coefficient minima were found for 1-butanol as solvent in NMP in the very dilute regions at (10 and 25) kPa. All systems were modeled satisfactorily with the nonrandom two-liquid (NRTL) equation for the Gibbs excess energy with a variable alpha parameter. Thermodynamic consistency testing of the isothermal data with the Van Ness (Van Ness, H. C. Pure Appl. Chem. 1995, 67, 859–872) direct test is discussed.

The removal and recycling of acetic acid from aqueous solutions is important for environmental protection and resource utilization. In this work, ionic liquid (IL) 1-ethyl-3-methylimidazolium diethylphosphate ([EMIM][DEP]) as an entrainer for the extractive distillation of the system water + acetic acid was investigated. Isobaric vapor–liquid equilibrium (VLE) data of the systems acetic acid + water, water + [EMIM][DEP], acetic acid + [EMIM][DEP], and water + acetic acid + [EMIM][DEP] have been measured at 101.32 kPa by using an improved Rose–Williams equilibrium still. The addition of [EMIM][DEP] showed a remarkable entrainer performance for the separation of acetic acid from its aqueous solution. The boiling point difference of the water + acetic acid system increased from 17.88 K (0 wt % IL) to 42.41 K (about 50 wt % IL), and the relative volatility (x1′ = 0.9) increased from 1.60 (0 wt % IL) to 5.28 (about 50 wt % IL). On the basis of the chemical theory and the Hayden–O’Connell (HOC) method, the para...

Vapor–liquid equilibrium (VLE) data for the system formed by acetonitrile, water, and dimethyl sulfoxide (DMSO) at 101.3 kPa are measured in this paper. The data have been correlated by the classical thermodynamic models: Wilson, universal quasichemical activity coefficient (UNIQUAC), and nonrandom two-liquid (NRTL). The results indicate that all of the models can correlate the VLE data successfully and Wilson model performances the best. The effects of DMSO with various contents on the acetonitrile + water system are explored. From the results, the azeotrope is eliminated by DMSO by the means of improving their relative volatility. Hence, DMSO is an effective solvent for separating the acetonitrile + water binary azeotropic system.

In this paper, 2-methoxyethanol (commercially known as methyl cellosolve) is proposed as a potential entrainer for extractive distillation processes involving water–alcohol mixtures. The two alcohols studied in this work are ethanol and 1-propanol. Thereby, isobaric vapor–liquid equilibrium (VLE) data at atmospheric pressure have been measured for the ternary systems ethanol + water + 2-methoxyethanol and 1-propanol + water + 2-methoxyethanol. Moreover, data of the binary systems formed by the 2-methoxyethanol and each of the other chemicals used (ethanol, water, 1-propanol) have been obtained. The well-known local composition models Wilson, UNIQUAC, and NRTL have been used to correlate binary VLE data. The model parameters obtained after correlation have been employed later to estimate the ternary VLE data and to discuss the suitability to employ 2-methoxyethanol as entrainer. According to the obtained results, 2-methoxyethanol is able to break the azeotrope formed in either of the two studied systems.

Isobaric vapor–liquid equilibrium (VLE) at 100 ± 0.1 kPa for the binary and ternary systems with 2-ethoxyethanol + ethylbenzene + dimethyl sulfoxide (DMSO) was determined with a modified Othmer still. All of the binary VLE data passed the Herington test and the Wisniak test. It was determined that 2-ethoxyethanol and ethylbenzene form a binary azeotrope at 127.4 °C, 48.5 mol % 2-ethoxyethanol at 100 ± 0.1 kPa. By adding DMSO as a solvent at 0.50 mass fraction, the binary azeotrope of 2-ethoxyethanol and ethylbenzene was broken successfully. The binary VLE data were correlated with Wilson, nonrandom two-liquid (NRTL), and universal quasichemical activity coefficient (UNIQUAC) models with minor deviations. The correlated binary interaction parameters were then used to predict the ternary VLE behavior, which fit well with the experimental data. These results provide a theoretical basis for the separation of a 2-ethoxyethanol and ethylbenzene mixture with DMSO as a promising solvent in extractive distillation.

In order to study the separation of 1-hexene and n-hexane, two solvents, 2-pentanol and ethyl-butyrate, are tested as possible entrainers for an extractive distillation. In this way, isobaric vapor–liquid equilibrium (VLE) data at 100 kPa have been measured for the two ternary systems formed by the initial mixture and one of the mentioned solvents: 1-hexene + n-hexane + ethyl butyrate and 1-hexene + n-hexane + 2-pentanol. VLE data for the four constituent binary systems have also been measured. These systems are 1-hexene + ethyl butyrate, n-hexane + ethyl butyrate, 1-hexene + 2-pentanol, and finally n-hexane + 2-pentanol. All binary systems show moderate positive deviations from the ideal behavior and do not form an azeotrope. The well-known local composition models Wilson, UNIQUAC, and NRTL have been used for correlating VLE data. Prediction with the UNIFAC method has been also obtained.

Isobaric vapor–liquid equilibrium (VLE) data for the ethanol (1) + water (2) system containing the ionic liquid (IL) 2-aminoethanol tetrafluoroborate ([MEA]+[BF4]−) (3) at atmospheric pressure (101.3 kPa) were measured with a modified Othmer still. The results showed that the azeotropic point can be broken at a specific IL mole fraction, indicating a significant salting-out effect following the order of x3 = 0.15 > x3 = 0.10 > x3 = 0.05. The IL [MEA]+[BF4]− may be a promising entrainer for the separation of ethanol and water with extractive distillation because it exhibits the highest separation ability when compared with other entrainers previously reported. The commonly used nonrandom two-liquid (NRTL) model was used for correlating the measured ternary VLE data.

Isobaric vapor–liquid equilibrium data for {methanol (1) + dimethyl carbonate (2) + 1-octyl-3-methylimidazolium (3)} where 3 is an ionic liquid ([OMIM]+[BF4]−) were obtained at 101.32 kPa using a modified Othmer still. The results indicated that [OMIM]+[BF4]− can transfer the azeotropic point and totally eliminate the azeotropic phenomena when its mole fraction is up to x3 = 0.20. This shows that [OMIM]+[BF4]− could be used as a alternative entrainer in the extractive distillation for methanol (1) + dimethyl carbonate (2) system. The measured ternary vapor–liquid equilibrium data were fitted with the NRTL.

Isobaric vapor–liquid equilibria (VLE) for the ternary system acetone + methanol +1-ethyl-3-methylimidazolium dicyanamide ([emim][DCA]) as well as the two solvent + IL binary systems have been obtained at 100 kPa using a recirculating still. The addition of [emim][DCA] to the solvent mixture produced a salting-out effect greater than that produced by other ionic liquids, showing that this ionic liquid is, until now, the best IL tested as an entrainer for the extractive distillation of the acetone + methanol mixtures, causing the azeotrope to disappear for an ionic liquid mole fraction as low as 0.031, at 100 kPa. This behavior can be explained on the basis of the influence of the IL concentration on the activity coefficient of each solvent in the binary mixtures. The electrolyte nonrandom two-liquid (NRTL) model was used for fitting successfully the experimental data.

Isobaric vapor–liquid equilibria were measured for the ternary system ethanol + water + ethylene glycol and its three constituent binary mixtures at 101.3 kPa using a modified Rogalski–Malanoski equilibrium still. The thermodynamic consistency of experimental binary data was checked using the point and area tests. The experimental binary data were then correlated by the Wilson, nonrandom two-liquid (NRTL), and universal quasichemical activity coefficient (UNIQUAC) equations. The ternary vapor–liquid equilibria data were predicted using the binary parameters for the three equations with good accuracy. The selectivity of ethylene glycol as entrainer for the separation of the azeotropic system ethanol + water by extractive distillation was discussed using the NRTL parameters.

Isobaric vapor–liquid equilibrium (VLE) data at 100 kPa have been measured for the ternary system cyclohexane + cyclohexene + diethyl carbonate and two constituent binary systems: cyclohexane + diethyl carbonate and cyclohexene + diethyl carbonate. Both binary systems show moderate positive deviations from ideal behavior and do not present an azeotrope. The VLE data have been correlated by the Wilson, universal quasichemical activity coefficient (UNIQUAC), and nonrandom two-liquid (NRTL) equations. The ternary system does not present an azeotrope and is well-estimated from binary interaction parameters. A prediction with the universal functional activity coefficient (UNIFAC)-Dortmund method has been also obtained.

Isobaric vapor–liquid equilibria (VLE) for the binary systems ethanol + 1-ethyl-3-methylimidazolium dicyanamide ([emim][DCA]) and water + [emim][DCA] as well as the VLE for the ternary system ethanol + water + [emim][DCA] have been obtained at 100 kPa using a recirculating still. The effect of [emim][DCA] on the ethanol + water system has been compared with that produced by another ionic liquid reported in the literature on the basis of the variation of solvent activity coefficients in ionic liquid (IL) + molecular solvent binary systems. From the results, [emim][DCA] appears as one of the best entrainers for the extractive distillation of the ethanol + water mixtures, causing the azeotrope to disappear at 100 kPa for ionic liquid mole fractions as low as 0.019. The experimental data were fitted with the Mock's electrolyte nonrandom two-liquid (NRTL) model, with a good agreement.

The selection of the most suitable selective solvent for separation processes such as extraction or extractive distillation plays an important role in the economical design. Since the largest deviation from ideality is observed at infinite dilution, limiting activity coefficients (γ∞) provide a useful tool for the optimal choice of the selective solvent. Therefore, activity coefficients at infinite dilution have been measured for 22 solutes (paraffins, olefins, chloroparaffins, aromatics, ketones, ethers, alcohols, and acetates) in fatty alcohols: octadecanol and eicosanol as a solvent. The measurements were carried out with the help of gas−liquid chromatography (GLC) at five and four temperatures, respectively. Furthermore, the observed temperature dependence of limiting activity coefficients is confirmed using excess enthalpy data. To determine the different interactions between the solutes and the solvents, the linear solvation energy relationship (LSER) or “Abraham method” is applied. To verify the ap...

Extractive distillation processes with and without salt have been proposed to produce anhydrous ethanol. For the feasible use of anhydrous ethanol for blending in gasoline, the energy required to produce anhydrous ethanol must be less than the energy generated by its combustion. The energy required to produce anhydrous ethanol by extractive distillation with ethylene glycol is approximately 19 MJ·kg−1, whereas it lies in the range of (5.02 to 9.27) MJ·kg−1 for extractive distillation with salt. Thus, the energy requirement in extractive distillation with salt is reduced. However, the use of nonvolatile salts involves problems encountered in its dissolution and subsequent crystallization. It is desired to make efforts to explore organic compounds to be used as an extracting agent in the production of anhydrous ethanol that could be consumed within the process or could be recovered with least capital/energy inputs. In view of the above, diaminomethanal (commonly known as urea) has been identified, and its e...

Isobaric vapor−liquid equilibria (VLE) for the ethanol + water + [emim][triflate] ternary system have been obtained at 100 kPa using a recirculating still. The ethanol + water binary system was also obtained. Furthermore, data were simulated with the Mock’s electrolyte nonrandom two-liquid (NRTL) model, using the solvent−solvent interaction parameters obtained from VLE data of the ethanol + water system and taking the solvent−ionic liquid (IL) interaction parameters for the other binary systems from previous works. The agreement between experimental and calculated data is very good, showing the predictive capacity of the model. The addition of [emim][triflate] produces the disappearance of the ethanol + water azeotrope when the mole fraction of ionic liquid in the liquid phase is greater than 0.023 at 100 kPa. The effect of [emim][triflate] on the ethanol + water system has been compared with that produced by other ionic liquids reported in the literature.

Isobaric vapor−liquid equilibrium (VLE) data for {propan-2-ol (1) + water (2) + 1-butyl-3-methylimidazolium tetrafluoroborate(3)} where 3 is an ionic liquid ([BMIM]+[BF4]−) at atmospheric pressure (101.32 kPa) were measured with a modified Othmer still. The results showed that the ionic liquid studied can transfer the azeotropic point and eliminate the azeotropic phenomena when its concentration is up to x3 = 0.20. This means that [BMIM]+[BF4]− can be used as a promising entrainer in the application of extractive distillation. However, the comparison of the salting-out effect of [BMIM]+[BF4]− with that of 1-ethyl-3-methylimidazolium tetrafluoroborate ([EMIM]+[BF4]−) was conducted. The measured ternary data were correlated using the NRTL equation.

The relative volatility αHfCl4/ZrCl4 in molten potassium chloroaluminate, KAlCl4, has been determined using equilibrium Rayleigh vaporization from mixtures containing a 36 % mass fraction of ZrCl4 + 1.4 % HfCl4. At these component concentrations and at a temperature near 450 °C, the ZrCl4 + HfCl4 vapor pressure over the melt is close to atmospheric pressure. According to preliminary results, αHfCl4/ZrCl4 ≈ 1.29 ± 0.04. The ZrCl4−KAlCl4 and HfCl4−KAlCl4 systems have been studied by visual thermal analysis. The results confirm that they are simple binary eutectic systems. According to our data, the eutectic temperature in the ZrCl4−KAlCl4 system is 519 K, and the eutectic is located at a ZrCl4 mole fraction of 0.08. The HfCl4−KAlCl4 system has a eutectic at an HfCl4 mole fraction of 0.171 with a melting point of 507.5 K.

Consistent vapor−liquid equilibrium data for the binary and ternary systems diisopropyl ether (1) + 2-propyl alcohol (2) + 3-methyl-1-butanol (3) are reported at 101.3 kPa. The diisopropyl ether (1) + 3-methyl-1-butanol (3) system shows positive deviations from ideal behavior, and the 2-propyl alcohol (2) + 3-methyl-1-butanol (3) system exhibits slight deviations from ideal behavior. The activity coefficients and the boiling points were correlated with their compositions by the Wilson, NRTL, UNIQUAC, and Wisniak−Tamir equations. It is shown that these models allow a very good prediction of the phase equilibria of the ternary system using the pertinent parameters of the binary systems. 3-Methyl-1-butanol eliminates the diisopropyl ether (1) + 2-propyl alcohol (2) binary azeotrope. The change of phase equilibria behavior is significant; therefore, this solvent seems to be an effective agent for the separation of the azeotropic mixture by extractive distillation.

Activity coefficients at infinite dilution are reported for ten solutes (heptane, octane, nonane, decane, benzene, toluene, ethylbenzene, o-xylene, m-xylene, and p-xylene) in sulfolane at temperatures T = (333.15 to 373.15) K. These data were measured with the help of gas−liquid chromatography (GC) in which sulfolane was used as the stationary phase. The results show good agreement with the activity coefficients at infinite dilution obtained from various methods in the literature. The temperature dependence of the activity coefficients found in the GC experiments could be confirmed using the excess enthalpy data. The present data can be used to determine and compare the selective effect caused by the addition of sulfolane to a given binary mixture in the separation processes such as extractive distillation and solvent extraction. The calculated selectivity suggests that both sulfolane and ionic liquid [HMIM+][BF4-] can act as a good solvent in separating aromatic and aliphatic compounds.

Consistent vapor−liquid equilibrium data for the binary and ternary systems dipropyl ether (1) + 1-propyl alcohol (2) + N,N-dimethylformamide (3) are reported at 101.3 kPa. The results indicate that dipropyl ether (1) + N,N-dimethylformamide (3) system exhibits a positive deviation from ideal behavior and that 1-propyl alcohol (2) + N,N-dimethylformamide (3) system deviates negatively from ideality. The activity coefficients of the solutions were correlated by the Wilson, NRTL, and UNIQUAC models. It is shown that these models allow a very good prediction of the phase equilibrium of the ternary system using the pertinent parameters of the binary systems. In addition, the Wisniak−Tamir relations were used for correlating bubble-point temperatures.