Isothermal vapour-liquid equilibria and excess molar enthalpies of hex-2-yne + methyl butyl ether and hex-3-yne + dibutyl ether mixtures (original) (raw)
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Journal of Chemical & Engineering Data, 2000
Experimental data are reported at 298.15 K of excess molar volumes V E and of excess molar enthalpies H E for binary and ternary mixtures of an alkanol (1-propanol or 1-butanol), an ether (diisopropyl ether or dibutyl ether), and an alkane (heptane). A vibrating-tube densitometer was used to determine V E. H E was measured using a quasi-isothermal flow calorimeter. The experimental results are used to test the applicability of the modified UNIFAC model for correlating H E and of the ERAS model for describing both V E and H E of binary mixtures as well as for predicting the excess properties of ternary mixtures containing an alkanol, an ether, and an alkane. For all investigated binary systems, a better description of the experimental data was achieved with the ERAS model in comparison with the modified UNIFAC model.
Journal of Chemical & Engineering Data, 2009
Experimental excess enthalpies of the ternary system dibutyl ether (DBE) + cyclohexane + 1-butanol and the corresponding binary systems at 298.15 K are reported. A quasi-isothermal flow calorimeter has been built and tested to make the measurements. All the binary and the ternary systems show endothermic character. The experimental data have been fitted using a polynomial equation for the binary and ternary systems. The values of the standard deviation indicate good agreement between the experimental results and those calculated from the equation. † Part of the special section "2008 European Conference on Thermophysical Properties".
Thermodynamics of n-octane+hexynes binary mixtures
Fluid Phase Equilibria, 2000
The vapor pressures of binary mixtures of n-octaneq hex-2-yne, or hex-3-yne and of the three pure components were measured by means of a static device at temperatures between 263 and 343 K. Molar excess Gibbs energies G E were calculated for several constant temperatures, taking into account the vapor phase imperfection in terms of the second molar virial coefficients, and were fitted to the Redlich-Kister equation. Calorimetric excess enthalpy H E measurements for n-octaneq hex-2-yne, qhex-3-yne, or qhex-1-yne are also reported at 303.15 K. These data, along with previous vapor-liquid equilibrum data for the n-octaneq hex-1-yne mixture, are examined on the basis of DISQUAC, an extended quasichemical group-contribution model. In terms of DISQUAC, the mixtures studied were characterized by only one type of contact: aliphaticralkyne. The interchange coefficients are not available in the literature, and are estimated in this work. The model consistently describes the excess functions G E and H E of the investigated n-octaneq alkynes mixtures.
Journal of Chemical & Engineering Data, 2012
In this work, the measurements of the isobaric vapor−liquid equilibrium (VLE) data at 101.32 kPa and the excess molar volumes (v E ), obtained at 10 K intervals of temperature in the range (288.15 to 328.15) K, for four binary systems comprised of methyl or ethyl butanoate with two alkanes (heptane and nonane) are presented. The v E are positive for the four mixtures, and their variation with temperature presents a thermal coefficient (∂v E /∂T) p > 0, and the behavior of these systems is interpreted. Experimental VLE data (p,T,x,y), obtained in a small capacity ebulliometer, present a positive consistency according to the method of Fredenslund. The methyl butanoate + heptane system presents a minimum boiling-temperature azeotrope with the following coordinates at the working pressure: (x 1,az = 0.404; T az = 367.65 K). Measurements of (T,p i o ) are also shown for all of the compounds and were determined using the same equilibrium equipment. Experimental data are correlated with an appropriate polynomial model proposed by the authors. A simultaneous correlation is performed for the characteristic VLE properties and the h E values taken from the literature. For the correlation of properties of methyl butanoate + heptane system, values of c p E from the literature were included in the correlation process. In all cases the multiproperty goodness of fit is acceptable. Another correlation procedure by successive steps in the order (x,c p E )→(x,h E )→(x,g E ) is also applied when the experimental data exist for the binaries studied; the results obtained with both procedures are similar. The universal functional activity coefficient (UNIFAC) method is applied to estimate the VLE values, h E and c p E , with different results. The VLE prediction is acceptable in all cases except for the methyl butanoate + heptane mixture, although the estimation of the other thermodynamic quantities is not adequate. a Uncertainties u are: u(T) = ± 0.02 K, u(n) = ± 0.0002, and u(ρ) = ± 0.02 kg·m −
Journal of Chemical & Engineering Data, 2005
This work shows the experimental values of excess properties H m E and V m E at two temperatures and the isobaric vapor-liquid equilibria at 101.32 kPa for binary systems composed of the first four butyl alkanoates with tert-butyl alcohol. None of the mixtures presented azeotropes, and all of the experimental data p-T-x-y were checked with a point-to-point test, proving to be thermodynamically consistent. The correlation of vapor-liquid equilibria and excess enthalpies was done simultaneously using different expressions with temperature-dependent coefficients. The model that gave the most acceptable correlation for the four mixtures was the polynomial expression proposed in this work. The NRTL model gave acceptable estimations of H m E , and the UNIQUAC, of equilibrium data. Two versions of the UNIFAC model were used: the original one with parameters by Hansen et al. and the version modified by Gmehling et al., which predicts the equilibrium data as the mixing enthalpies. This last version estimated H m E with differences of around 20% for the four mixtures at different temperatures. The predictions made for equilibria are considered to be acceptable for the mixtures (butyl propanoate or butanoate + tert-butanol). The estimations made using the original version by Hansen et al. were not good.
Journal of Chemical & Engineering Data, 2007
In this work, we report the experimental values of the excess quantities H m E and V m E and the isobaric equilibrium data (VLE) at 101.32 kPa for the four mixtures of alkyl methanoates (methyl to butyl) and hexane. The results indicate that for these four mixtures (∂H m E /∂T) p > 0 and(∂V m E /∂T) p > 0. VLE data were found to be thermodynamically consistent with the Fredenslund method. All the binary mixtures presented here, except for the system (butyl methanoate + hexane), present a minimum-boiling temperature azeotrope with coordinates (x az , T az /K), (0.832, 302.62) for (methyl methanoate + hexane), (0.703, 323.32) for (ethyl methanoate + hexane), and (0.283, 339.10) for (propyl methanoate + hexane). Simultaneous correlations performed with the VLE data and excess enthalpies using a simple polynomial model, with temperature-dependent coefficients, produced acceptable estimations. Application of the UNIFAC model in the versions of Hansen et al. (Ind.