NRTL Activity Coefficient Model Research Articles

Separation of azeotrope (allyl alcohol + water): Isobaric vapour-liquid phase equilibrium measurements and extractive distillation

Abstract To separate the azeotrope of (allyl alcohol + water) by extractive distillation, N-methyl-2-pyrrolidone, N-methyl formamide and ethylene glycol were selected as extractive agents, and the isobaric VLE data for the binary systems of (allyl alcohol + N-methyl-2-pyrrolidone), (allyl alcohol + N-methyl formamide) and (allyl alcohol + ethylene glycol) were determined at 101.3 kPa by a modified Rose type recirculating still. The thermodynamic consistency of the experimental data was checked by the Herington, van Ness, infinite dilution, and pure component consistency method. Meanwhile, the experimental data were correlated by the NRTL, UNIQUAC and Wilson activity coefficient models, and the binary interaction parameters of the three models were regressed. All the correlated results by the NRTL, UNIQUAC, and Wilson models agreed well with the experimental data. Furthermore, the extractive distillation processes with the extractive agents were presented to separate the azeotrope of (allyl alcohol + water).

Isobaric Vapor–Liquid Equilibrium for Binary System of Tetrahydrofuran + 1,4-Butanediol and gamma-Butyrolactone at 50.0 and 70.0 kPa

Isobaric vapor–liquid equilibrium (VLE) data for two binary systems, tetrahydrofuran (THF) + 1,4–butanediol (BDO) and THF + gamma-butyrolactone (GBL), were measured at pressures of 50.0 and 70.0 kPa. The experiment data were regressed using maximum likelihood method, and binary interaction parameters were estimated for Wilson, NRTL, and UNIQUAC activity coefficient models by Aspen Plus V9.0. All of the models match well with the experimental data. All the experimental data passed the thermodynamic consistency test by Redlich–Kister area test and Van Ness test. The two binary systems both exhibit positive deviations from ideality.

Phase equilibria of clathrate hydrates in CO2/CH4 + (1-propanol/2-propanol) + water systems: Experimental measurements and thermodynamic modeling

Hydrate equilibrium/dissociation conditions of methane/carbon dioxide in the presence of aqueous solutions of 1-propanol/2-propanol have been studied in this communication. The hydrate dissociation conditions of water + CO2 and water + CO2 + 2-propanol systems have been measured in concentration range of 0, 0.02, 0.05, 0.10, 0.15 and 0.25 mass fractions in 274.5–283.1 K and 1.93–4.54 MPa, temperature and pressure ranges using an isochoric pressure-search method. A thermodynamic model has been developed to estimate the hydrate dissociation conditions for the systems of water + CH4/CO2 + 1-propanol/2-propanol based on combinations of van der Waals and Platteeuw model, Peng-Robinson equation of state (PR EOS), and NRTL and Wilson activity coefficient models. The parameters of Langmuir constants have been obtained by fitting experimental data while structural, and interaction parameters of activity coefficient models have been taken from literature. Based on our experimental data, 2-propanol likely acts as thermodynamic inhibitor for CO2 hydrate. The results of the model are in satisfactory agreement with the experimental data.

Study on the Solubilities of Mononitro-Substituted Products of Nitration of m-Toluic Acid in Several Solvents at Temperatures between 297.65 and 351.75 K

Mononitro-substituted products derived from the nitration of m-toluic acid are 3-methyl-4-nitrobenzoic acid, 3-methyl-2-nitrobenzoic acid, and 5-methyl-2-nitrobenzoic acid, which are all crucial intermediates of pesticides and medicines. The solubilities of 3-methyl-4-nitrobenzoic acid, 3-methyl-2-nitrobenzoic acid, and 5-methyl-2-nitrobenzoic acid in water, methanol, ethanol, n-propanol, formic acid, acetic acid, and propanoic acid were measured at different temperatures (297.65–351.75 K) and under atmospheric pressure. As expected, the same solute has different solubilities in different solvents, and the dissolved amounts of these three solutes are also diverse in the same solvent. Subsequently the experimental solubility data of three mononitro-substituted products of m-toluic acid nitration in several solvents were correlated with the modified Apelblat equation and the NRTL activity coefficient model, and the calculated values are in excellent agreement with known experimental data in the temperature ...

Extraction of o-, m- and p-cresol from aqueous solution with methyl isopropyl ketone: Equilibrium, correlations, and COSMO-RS predictions

In this work, methyl isopropyl ketone (MIPK) was studied to extract o-, m-, p-cresol from water at 333.2 and 343.2K. The liquid–liquid equilibrium (LLE) data for the ternary systems, MIPK+o-, m-, p-cresol+water, were determined at 101.3kPa. The extraction performance of MIPK for cresols was evaluated by the distribution coefficient and selectivity. High distribution coefficients and selectivity values indicate MIPK is a promising extractant to separate cresols from wastewater. The experimental LLE data were accurately correlated by using the NRTL and UNIQUAC activity coefficient models, with root mean square deviation (RMSD) values below 1%. The conductor-like screening model for real solvent (COSMO-RS) model was used to predict the phase diagrams of the studied systems, and the RMSD from the experimental data are ∼5% (o-cresol), ∼3% (m-cresol), ∼2.5% (p-cresol) respectively. Furthermore, molecular dynamics (MD) simulations were employed to study the effect of temperature on the hydrogen bonds in the studied systems. The results were used to adjust the hydrogen-bonding parameter of the COSMO-RS model, yielding phase diagram closer to the experiments.

Isobaric Vapor–Liquid Equilibrium Data for the Binary Systems of Dimethyl Carbonate with Xylene Isomers at 93.13 kPa

Isobaric binary vapor–liquid equilibrium (VLE) data for dimethyl carbonate with xylene isomers (p-xylene, m-xylene, o-xylene, and ethylbenzene) were measured at the local atmospheric pressure of 93.13 kPa by using a dynamic recirculation still. The experimental VLE data were tested and found to be thermodynamically consistent by Herington and Van Ness consistency test. The experimental VLE data were correlated using the Wilson, NRTL, and UNIQUAC activity coefficient models and binary interactions parameters were estimated using a suitable objective function. The absolute mean deviation between the experimental and the model predicted values of vapor phase composition and total pressure was well within acceptable limits. No azeotrope was observed in any of the binary pairs and appeared to be easy for separation using conventional distillation method.

Can a Cubic Equation of State Model Bitumen–Solvent Phase Behavior?

Cubic equations of state (CEoS), such as the advanced Peng–Robinson (APR) EoS, are convenient for use in commercial simulators and have successfully fit saturation pressures and asphaltene onset points for bitumen–solvent systems using simple quadratic mixing rules. However, this approach does not accurately predict asphaltene precipitation yields. In this study, the APR EoS with several sets of asymmetric mixing rules is evaluated against saturation pressure and asphaltene yield data for n-pentane diluted bitumen. The asymmetric van der Waals, Sandoval et al., and two forms of Huron–Vidal mixing rules with an NRTL (non-random liquid theory) activity coefficient model are considered. The use of asymmetric mixing rules significantly improves the match to asphaltene yield data; however, the yields are still underpredicted at high solvent contents, and the tuning parameters that give the best match for asphaltene yield data are not predictive or easily correlated for other solvents. The APR EoS with symmetri...

Separation of azeotrope (2,2,3,3-tetrafluoro-1-propanol + water): Isobaric vapour-liquid phase equilibrium measurements and azeotropic distillation

In this work, chloroform and p-xylene were selected as azeotropic agents to separate the azeotrope of {2,2,3,3-tetrafluoro-1-propanol (TFP)+water} by azeotropic distillation. The isobaric vapour-liquid equilibrium data for the binary systems of (TFP+water), (TFP+chloroform), and (TFP+p-xylene) were determined at 101.3kPa by a modified Rose type recirculating still. The thermodynamic consistency of the experimental data was checked by the Herington, van Ness, infinite dilution, and pure component consistency method. The experimental results were correlated by the NRTL, UNIQUAC and Wilson activity coefficient models, and the binary interaction parameters of the three models were regressed. All the correlated results by the NRTL, UNIQUAC, and Wilson models show good agreement with the experimental data. Furthermore, the distillation synthesis ternary maps for the systems (TFP+water+chloroform) and the (TFP+water+p-xylene) were obtained with the regressed interaction parameters of the NRTL model, and two distillation processes were presented to separate the azeotrope of (TFP+water).

Techno-economic study of enhanced absorber–regenerator configurations for improving an industrial Sulfinol-M-based acid gas removal processes

Abstract In this study, the rigorous simulation and design of an industrial Sulfinol-M-based acid gas removal (AGR) process was developed. All simulations were performed using Aspen HYSYS with extended NRTL activity coefficient model for the liquid phase and the Peng–Robinson state equation for the vapor fugacity coefficients. The simulation results from VMGSim and Aspen HYSYS were compared with design data from an integrated gasification combined cycle power plant. Several enhanced absorber–regenerator configurations were presented to improve AGR process efficiency. Sustainability analysis was conducted to assess these process alternatives in terms of energy requirements, costs, and environmental impacts. The results showed that the proposed self-heat recuperation configuration could reduce the energy requirements, total annual costs, carbon footprint by 74.7%, 40.1%, and 48.9%, respectively, compared with the conventional configuration.

Vapor–liquid equilibrium in the ternary system isobutyl alcohol + isobutyl acetate + N, N-dimethyl acetamide and the binary systems isobutyl alcohol + N, N-dimethyl acetamide, isobutyl acetate + N, N-dimethyl acetamide at 101.3 kPa

The isobaric Vapor-Liquid Equilibrium (VLE) data at 101.3 kPa were measured for the binary systems isobutyl alcohol + N, N-dimethyl acetamide (DMAC), isobutyl acetate + N, N-dimethyl acetamide and the ternary system isobutyl alcohol + isobutyl acetate + N, N-dimethyl acetamide using an all glass dynamics recirculating still. The isobutyl alcohol + DMAC system exhibits negative deviation from Raoult's law and isobutyl acetate + DMAC system deviates positively from ideal solution. The thermodynamic consistency of the binary VLE data was checked by Herington method and Wisniak point-to-point method. The NRTL, UNIQUAC and Wilson activity coefficient models were used to correlate the binary VLE data in order to obtain the binary interaction parameters which were used to predict ternary VLE data. The predicted results agree well with the experimental data. The results indicate that the solvent DMAC can greatly enhance the relative volatility of isobutyl acetate to isobutyl alcohol, and azeotrope of isobutyl acetate and isobutyl alcohol will be broken if the mole fraction of DMAC is greater than 0.361. The effects of the solvents 1-hexanol, butyl propionate (BUP), N, N-dimethyl formamide (DMF) and N, N-dimethyl acetamide (DMAC) were compared, and the selectivity of DMAC was the largest. The solvent DMAC is a promising extractive agent for the separation of mixtures of isobutyl alcohol and isobutyl acetate by extractive distillation.

Liquid–Liquid Equilibrium for the Ternary Systems Methyl tert-Butyl Ketone + o-, m-, p-Cresol + Water at (298.2, 313.2, and 323.2) K

Liquid–liquid equilibrium (LLE) for the methyl tert-butyl ketone (MTBK) + o-, m-, and p-cresol + water ternary systems, at temperatures of (298.2, 313.2, and 323.2) K and 101 kPa, were determined in this work. High distribution coefficient and selectivity values were calculated from the LLE data, which indicated that MTBK extracted cresols from wastewater with high efficiency. MTBK also has good physical properties (e.g., low solubility in water, suitable boiling point). The experimental results were regressed and correlated by the NRTL and UNIQUAC activity coefficient models, which both predicted LLE data in close agreement with experiments with RMSD below 3.5%. The corresponding binary interaction parameters were also regressed by these two models, which would be useful for separation process designing or optimizing.

Vapor–Liquid Equilibrium for Methyl Isobutyl Ketone (MIBK) + (1-Propanol or 2-Propanol) Binary Mixtures

Isothermal vapor–liquid equilibrium (VLE) data for 1-propanol + methyl isobutyl ketone at 338.15, 353.15, and 368.15 K and 2-propanol + methyl isobutyl ketone were measured at 323.15, 338.15, and 353.15 K. All the measurements were undertaken on a recirculating VLE glass still operated at isothermal conditions. The experimental VLE data for all the measured binary systems were correlated with the Wilson and NRTL activity coefficient models using the gamma–phi approach (γ–Φ) with the Hayden and O’Connell correlation employed for calculating the second virial coefficients that are used in accounting for nonidealities in the vapor phase. The models provided satisfactory correlation of the measured alcohol–ketone-binary mixtures at all the temperatures reported. The thermodynamic consistency of the data was checked using the point test method of Van Ness et al. (Van Ness, H. C., Byer, S. M., and Gibbs, R. E. AIChE J. 1973, 19, 238−244) as well as the more rigorous direct test of Van Ness (Van Ness, H. C. Pure...

Measurement and Modeling of Phase Equilibrium, Volumetric Properties and Molar Refractivity of 2-Methylpropan-2-ol + Ethane-1,2-diol

2-Methylpropan-2-ol, an important fine chemical, may be dehydrated during extractive distillation with glycols as entrainer. Experimental isobaric phase equilibrium studies were carried out on binary mixtures of 2-methylpropan-2-ol with ethane-1,2-diol, as an entrainer, at the local atmospheric pressure of 94.99 kPa and at sub-atmospheric pressures of 19.99, 39.99, 59.99, 78.79 kPa using a Sweitoslawski-type ebulliometer. The Wilson and NRTL activity coefficient models were used to correlate the experimental results and the binary interaction parameters were obtained using the Generalized Reduced Gradient optimization technique. UNIFAC was also used to predict the deviations in bubble temperatures. Moreover, the variation in density, refractive index values and other derived properties (excess molar volumes, partial molar volumes and deviations in molar refractivity) were explored at 303.15, 313.15, 323.15 and 333.15 K to understand the shift of equilibrium with the variation in the mixture composition for the conformational state of the molecules. The Redlich–Kister polynomial equation was used to correlate the excess molar volumes and deviations from molar refractivity. Different theoretical mixing rules (Lorentz–Lorenz, Wiener, Heller, Gladstone–Dale and Arago–Biot) are investigated and reported in terms of average percentage deviation. Furthermore, the Prigogine–Flory–Patterson theory was used to predict the trend of the dependence of excess molar volumes on composition for the present system.

Measurements and Thermodynamic Models for the Separation of 2-Methoxyethanol and Water Azeotropic Mixtures via Different Solvents

This work reveals experimental liquid–liquid equilibria (LLE) for ternary systems of (2-methoxyethanol + water + solvents) with methyl tert-butyl ether, ethyl acetate, and trichloromethane at 313.15 K and dichloromethane as solvent at 298.15 K under 101 kPa. The extraction capacity of the aforementioned solvents has been tested when it comes to the distribution ratio and separation factor according to the experimental data. The calculation results demonstrate that trichloromethane is an available solvent for extraction applications. Simultaneously, the reliability of the experimental LLE data was checked by Othmer–Tobias and Hand correlations, and all of the linear correlation coefficients were greater than 0.98. The experimental LLE values were regressed to obtain binary interaction parameters with both NRTL and UNIQUAC activity coefficient models. Both models shows satisfactory agreement with all of the root-mean square deviation values below 0.50.

Experimental solubility data for prednisolone and hydrocortisone in various solvents between (293.2 and 328.2) K by employing combined DTA/TGA

Solubility measurements were performed for the systems (11β)-11,17,21-trihydroxypregna-1,4-diene-3,20-dione (prednisolone) and (11β)-11,17,21-trihydroxypregn-4-ene-3,20-dione (hydrocortisone) in 10 solvents at atmospheric pressure within the temperature range, T=(293.2 to 328.2)K by employing combined digital thermal analysis and thermal gravimetric analysis (DTA/TGA) to determine liquid phase compositions at saturation. The maximum solubility for prednisolone and hydrocortisone was in N,N dimethylformamide at 328.2K with x1=0.0141 and x1=0.0142 respectively. The lowest solubility was found to be prednisolone and hydrocortisone in water at 293.2K with x1=0.0000105 and x1=0.0000115 respectively. The composition data was modelled using the Tsuboka-Katayma modified Wilson and NRTL activity coefficient models. There is satisfactory agreement between the experimental results and the models chosen. Furthermore, melting points and enthalpies of fusion of prednisolone and hydrocortisone were determined by combined DTA/TGA. The enthalpy of fusion and melting point of prednisolone and hydrocortisone was found to be 36,145J·mol−1 and 514.5K and 33,900J·mol−1 and 486.1K respectively.

Measurement and Prediction of Vapor–Liquid(−Liquid) Equilibria in Ternary Systems Containing Water, an Organic Component, and Cyclohexanol

The isothermal vapor–liquid(−liquid) equilibria for the water + cyclohexane + cyclohexanol, water + toluene + cyclohexanol, and water + cyclohexylamine + cyclohexanol ternary systems are presented. The experimental data were determined by the dynamic method in a modified Röck and Sieg circulation still between 333.15 and 363.15 K at 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).

Liquid–liquid equilibria in the ternary systems {water + cyclopentanone + benzene or toluene} at different temperatures: Experimental data and correlation

The liquid–liquid equilibrium (LLE) data of the ternary systems (water +cyclopentanone +benzene or toluene) were determined at T=303.2, 313.2, and 323.2K, under 101kPa. The reliability of the experimental tie-line data was sufficiently checked by the empirical Hand and Bachman equations. The distribution coefficient and separation factor were used to investigate the distribution of cyclopentanone between water and solvents. The results show that the separation factor decreases with increasing cyclopentanone amounts in organic phase and the influence of temperature is light in the study. The experimental tie-line data were correlated well with the NRTL and UNIQUAC activity coefficient models with a root mean square deviation (RMSD) as low as 0.81 and 0.50.

Liquid-liquid separation of hex-1-ene from hexane and cyclohexene from cyclohexane with ionic liquids

The objective of this work was to explore the feasibility of extraction of hex-1-ene from hexane and cyclohexene from cyclohexane with different ionic liquids (ILs). The liquid-liquid equilibrium (LLE) was studied in various binary and ternary mixtures of {IL (1)+hex-1-ene (2)+hexane (3)} and {IL (1)+cyclohexene (2)+cyclohexane (3)} at T=298.15K and p=0.1MPa. The ILs studied are as follows: 1-butyl-3-methylimidazolium dicyanamide, [BMIM][DCA], 1-butyl-3-methylimidazolium tricyanomethanide, [BMIM][TCM] and 1-butyl-4-cyanopyridinium bis{(trifluoromethyl)sulfonyl}imide, [BCN4PY][NTf2]. The results, obtained by us from the limiting activity coefficients results showed the excellent selectivity by using the ILs with (CN) groups and large solute distribution ratio by using the bis{(trifluoromethyl)sulfonyl}imide-based ILs. The chromatography analysis results indicated that the ILs used as a separation solvents were not present in the hydrocarbon-rich layer, which is convenient, because this eliminates the step needed for the separation of the solvent. The results showed that [BMIM][DCA] revealed large selectivity of extraction and acceptable solute distribution ratio in separation of hex-1-ene/hexane and cyclohexene/cyclohexane compounds. The NRTL activity coefficient model was used to correlate the LLE results.

Isothermal vapor-liquid equilibria, excess molar volume and the deviation of refractive indices for binary mixtures of 1-butanol, 1-hexanol, 3-methyl-1-butanol and butyl acetate

Experimental vapor-liquid equilibrium (VLE) data and mixture properties are reported toward developing a process for the separation of the traditional ABE (acetone + butanol + ethanol) fermentation. Isothermal VLE measurements at 343.2 K were performed by using headspace gas chromatography (HSGC) for binary systems {1-butanol + 3-methyl-1-butanol}, {1-butanol + 1-hexanol}, {butyl acetate + 3-methyl-1-butanol}, {butyl acetate + 1-hexanol} and {3-methyl-1-butanol + 1-hexanol}. The experimental VLE binary data were correlated using the Wilson, NRTL and UNIQUAC activity coefficient model equation. In addition, a digital vibrating tube densimeter and precision digital refractometer were used to determine the excess molar volume (VE) and the deviation of the refractive indices (ΔR) for the same binary systems at 298.2 K. The Redlich-Kister equation was employed to show that the determined VE and ΔR data were well correlated.

Measurement and prediction of liquid-liquid equilibria in ternary systems containing water, an organic component, and cyclohexanol

The liquid-liquid equilibria of the four ternary mixtures water + heptane + cyclohexanol, water + toluene + cyclohexanol, water + cyclohexane + cyclohexanol, and water + cyclohexylamine + cyclohexanol were measured at 298.15 K and 323.15 K at atmospheric pressure. The binodal curves were determined by photometric turbidity titration.Our experimental data are compared with the prediction results from both UNIQUAC and NRTL activity coefficient models and the equation of state proposed by Elliott, Suresh, and Donohue (ESD EOS). For this purpose, interaction parameters were determined using binary phase equilibrium data. Due to the sparse amount of binary equilibrium data in literature, the vapour-liquid equilibrium in the binary toluene + cyclohexanol system was determined at 333.15 K and 363.15 K at reduced pressure. When predicting the experimental LLE behaviour of the considered systems, ESD EOS seems to be superior to the UNIQUAC and NRTL approach.