Here, a group contribution statistical associating fluid theory equation of state (SAFT EOS) (GC-SAFT) proposed earlier by our group (Tamouza et al., Fluid Phase Equilib. 2004, 222-223, 67-76) is extended to some asymmetric systems, using a method for correlating the k ij binary parameters, using only pure compound parameters. The method is inspired by London's theory of dispersive interactions and correlates the k ij values to the "pseudo-ionization energies" of compounds i and j (denoted as J i and J j , respectively). A group contribution for the latter parameters is also proposed, in view of obtaining a more-predictive model. Correlation tests of phase equilibria are conducted on some CO 2 + n-alkane systems. Using the parameters thus obtained, the phase envelopes of other CO 2 + n-alkane systems, as well as methane + n-alkane and ethane + n-alkane systems, were fully predicted. Correlation and predictions are qualitatively and quantitatively satisfactory. The deviations are within 4%-5% (i.e., comparable to those obtained on previously investigated systems).

The present paper proposes to use the group contribution (GC) polar perturbed-chain-statistical associating fluid theory (GC-PPC-SAFT) equation of state (EoS), that has already been used with success on various organic mixtures, and extend it to model simultaneously the liquidÀliquid equilibrium (LLE) and vaporÀliquid equilibrium (VLE) of hydrocarbons þ water systems, in wide ranges of pressure and temperature. Mixtures of water with aliphatics, aromatics, alcohols, carbon dioxide, and hydrogen sulfide have been investigated. Pure water is assumed associative (according to the 4C association scheme) and dipolar; the aromatic compounds are quadrupolar. Alcohols are autoassociative with a 3B association scheme. A cross-association between water and alcohols or H 2 S is taken into account. Cross association between water and other polar molecules (CO 2 or aromatic molecules) was also taken into account explicitly. Only one set of cross association parameters ε cross /k and k cross values were used for all the water þ aromatic mixtures considered here. ε cross /k was adjusted on experimental data, whereas k cross is set to the value found for pure water. For each system, the same binary interaction parameter k ij was used for simultaneous modeling LLE and VLE. This parameter was correlated to pseudo-ionization energy parameters for pure compounds through London's dispersion force theory, and reused from previous works [

A group-contribution statistical associating fluid theory equation of state (GC-SAFT EOS) that was proposed by Tamouza et al. [Tamouza et al. Fluid Phase Equilib. 2004, 222−223, 67−76], which was extended in the first part in this series of papers to the asymmetric systems CO2 + n-alkane, methane + n-alkane, and ethane + n-alkane, is further tested here on binary mixtures that contain aromatic hydrocarbons, n-alkanes, CO2, N2, and H2S. The method for correlating the binary interaction parameters (k ij ), which is inspired by Londonʼs theory of dispersive interactions, uses only pure compound adjustable parameters (“pseudo-ionization energies” of compounds i and j, denoted as J i and J j ). A group contribution for the latter parameters also is used for n-alkane and alkyl benzene series. Numerous prediction tests on the aforementioned cited systems were performed in a systematic and comprehensive way. Predictions are both qualitatively and quantitatively satisfactory, within deviations (4%−5%) that are comparable to those obtained on previously investigated systems (n-alkane + n-alkane, n-alkane + aromatic, n-alkane + n-alkanol).

This study examines an accuracy of CP‐PC‐SAFT attached by the 4C cross‐association scheme and zero values of binary parameters in predicting the high temperature‐high pressure phase behavior in aqueous systems of aromatic compounds containing one and two benzoic rings, CO2 and cis‐decalin. In spite of the noteworthy complexity of these systems and the entirely predictive nature of the current approach, it correctly predicts the topology of phase behavior and typically yields the quantitatively accurate estimations of critical loci and the hydrocarbon–rich liquid phases in wide range of conditions. The available single phase volumetric data are also predicted accurately. Unfortunately, it is not a case of the water–rich phases exhibiting very small hydrocarbon concentrations. Nevertheless, the model is still capable of capturing the solubility minima characteristic for these phases around the room temperature. Predictions of the recent version of Simplified PC‐SAFT proposed by Liang et al. (2014) are also discussed. © 2017 American Institute of Chemical Engineers AIChE J, 63: 4124–4135, 2017

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This investigation continues a series of studies evaluating the capability of the recently proposed CP‐PC‐SAFT and sPC‐SAFT of Liang et al. to estimate the thermodynamic properties of aqueous systems in the entirely predictive manner. Similarly to the previously considered systems, CP‐PC‐SAFT remains a realistic estimator of the available data on critical loci, high pressure‐high temperature phase equilibria and volumetric properties also in the cases of non‐polar gases and non‐aromatic hydrocarbons from argon and nitrogen till n‐eicosane and squalene while keeping zero values of binary parameters. Nevertheless, such application of the model poses certain unavoidable compromises on its accuracy. Inter alia, CP‐PC‐SAFT is a particularly inaccurate estimator of the water‐rich liquid phases away from the critical points. sPC‐SAFT predicts these data in a more reliable manner. Moreover, its predictive capability goes beyond the liquid phases and it exhibits a remarkable accuracy in forecasting various phase equilibria below the critical point of water. © 2017 American Institute of Chemical Engineers AIChE J, 2017

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