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The objective of this work was to study the behavior of the azeotropic points of the methanol + DMC system under elevated pressures. We obtained isothermal vapor–liquid equilibria (VLE) data for this system at 383.15, 403.15, and 413.15 K by a static method. The azeotropic points were determined from the experimental VLE data. The temperature and pressure dependencies of the determined azeotropic points are discussed and compared with ones measured at reduced pressure. The experimental VLE data were represented by two activity coefficient models (non-random two-liquid and Wilson models). We also tested the modified UNIFAC (Dortmund) model for prediction of the VLE and azeotropic points. The azeotropic points of this system could be obtained over the pressure range from reduced pressures to elevated ones.

Isothermal P–x vapor–liquid equilibrium and excess enthalpy (HE) data were experimentally determined for the 10 binary systems hexane, heptane, 1-octene, benzene, toluene, ethanol, methanol, ethyl acetate, dibutyl ether, and dichloromethane with N,N- dimethylacetamide using the static synthetic method and isothermal flow calorimetry, respectively. The experimental data from this work together with data taken from literature were used for the extension of the group contribution method Modified UNIFAC (Dortmund).

For process development and simulation, the group contribution concept can be successfully applied for the estimation of the missing pure component and mixture properties. This concept has the great advantage that only a limited number of group interaction parameters is required. With the support of a company consortium founded 1996 at the University of Oldenburg, the group contribution model modified UNIFAC (Dortmund) for the prediction of phase equilibria and excess properties has been continuously revised and extended. Within the consortium the number of available group interaction parameters has been doubled. At the same time, the reliability of the results was greatly improved, and the range of applicability was extended to ionic liquids, polyethers, and so forth, and systems for which no experimental data are available, e.g., reactive systems. In this paper the group interaction parameters for the sulfur groups sulfones, sulfides, and disulfides are given. Furthermore, the current status of the cons...

Liquid–liquid equilibria (LLE) of water + acetic acid + dimethyl carbonate were experimentally specified at (298.2, 308.2, and 318.2) K. Each diagram was obtained through specifying binodal curves and tie-lines. The reliability of the experimental tie-line data was calculated by the Othmer–Tobias correlation. The nonrandom two-liquid (NRTL) and unified quasichemical activity coefficient (UNIQUAC) models were used to obtain the binary interaction parameters of the experimental tie-line data. However, universal functional (UNIFAC) and modified UNIFAC methods were used as well to predict the phase equilibrium in the system specified from experimental data using the interaction parameters between CH3, OCOO, COOH, and H2O functional groups. Distribution coefficients and separation factors were assessed for the immiscibility region.

The objective of this study is the selection of a suitable entrainer for the separation of the binary azeotropic mixture, namely methanol + dimethyl carbonate (DMC) by extractive distillation. In this study, 2-ethoxyethanol and 4-methyl-2-pentanone were considered as entrainer candidates for the separation of methanol and DMC. Isobaric vapor–liquid equilibria (VLE) were measured for the ternary mixtures methanol + DMC + 2-ethoxyethanol and methanol + DMC + 4-methyl-2-pentanone, and for their constituent binary mixtures, under reduced pressures of 66.66 kPa and 93.32 kPa. Experimental VLE data for the constituent binary mixtures were represented by the Wilson and the NRTL model. The VLE predictions for two ternary mixtures were compared with the experimental VLE data on the basis of the Wilson or NRTL parameters obtained from the constituent binary VLE data. The modified UNIFAC (Dortmund) model was also used for the prediction of the binary and ternary mixtures. The solvent effects of the two entrainer candidates investigated are discussed using the predicted results for the ternary mixtures and both 2-ethoxyethanol and 4-methyl-2-pentanone were found to be suitable entrainers for the separation of methanol and DMC. When the selectivity of 2-ethoxyethanol and 4-methyl-2-pentanone are compared, it could be concluded from the separation factors that 4-methyl-2-pentanone shows a higher selectivity.

This article presents a comparative study about the predictive capability of COSMO-SAC and COSMO-RS(Ol) models with respect to excess enthalpies of various binary systems. Results of the group cont...

Reliable azeotropic data have been measured for the binary systems ethanol+diethoxymethane, diethoxymethane+1-propanol, diethoxymethane+heptane, and cyclohexane+diethoxymethane with the help of a wire band column. Additionally molar excess enthalpies (HE) for the binary mixtures of diethoxymethane with hexane, 1-octene, methanol and ethanol at 363.15 K have been determined with an isothermal flow calorimeter. The experimental data were compared with the results using the available “ether” main group of the group contribution method Modified UNIFAC (Dortmund), which is a well-known model for the prediction of phase equilibria and excess properties. For the description of the HE data a Redlich–Kister polynomial was also used. The aim of this work is to supplement the available data base for acetal systems required for the introduction of a new “acetal” group in the Modified UNIFAC (Dortmund) model.

Solid−liquid equilibria (SLE) for the following seven systems have been measured by the visual technique: benzene, toluene, cyclohexane, 1-propanol, methanol, water, and 2-pentanone with e-caprolactone. For the description of the SLE data the NRTL model and the group contribution method Modified UNIFAC (Dortmund) were used.

Predictions of vapor–liquid equilibria at high temperatures and pressures were obtained by applying a modified procedure using the Huron–Vidal mixing rule based on available activity coefficients at infinite dilution and low pressures. These activity coefficients were calculated with so-called conductor-like screening model for real solvents (COSMO-RS) and with a variation of this model, known as segment activity coefficient (COSMO-SAC) model. In this work, the performances of the mixing rule (HVID model) coupled with the SRK equation of state and a reduced UNIQUAC model are presented for six binary systems and a ternary system, whose VLE data are available over a large temperature and pressure range.