This work expands the scope of the SAFT-VR Mie framework by considering its application and that of its polar variant (SAFT-VR Mie-GV) to real phase behavior in alcohol/n-alkane and alcohol/water systems. This requires supplementing existing parameters for alcohols with parameter sets for all primary and secondary alcohols in the C1–C5 range. Parameter degeneracy is overcome using a novel variation of the discretized regression approach, by considering the average absolute deviations (AADs) for the mixture VLE resulting from each regressed parameter set in the discretized εAB /k–n p space. The resulting parameter sets exhibit excellent predictions for the alcohol/n-alkane and alcohol/water systems. The comparable results of the polar and nonpolar variants suggest that an explicit polar term is not necessary to describe the phase behavior of alcohols in the considered mixtures. The choice of association scheme is more significant, with the 2C scheme yielding excellent predictions for alcohols in mixtures with both alkanes and water.

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SAFT-VR Mie is extended to quadrupolar molecules and their mixtures by incorporating an explicit Helmholtz contribution for quadrupole−quadrupole interactions. Two quadrupolar terms are considered: the quadrupolar theory of Larsen and coworkers, and that of Gross, yielding VRM-L and VRM-G, respectively. Each model requires an additional parameter for quadrupolar molecules. The two quadrupolar models are evaluated by means of their ability to model the following binary systems: CO 2 or benzene with n-alkanes or 1-alkanols and binary mixtures of quadrupolar molecules. VRM-L and VRM-G offer significant improvements over nonpolar SAFT-VR Mie in describing the VLE of the CO 2 + n-alkane systems, while only the benzene + n-hexane system requires the additional quadrupolar term for accurate description. Cross-association in CO 2 + 1-alkanol systems is accounted for by fine-tuning the association parameters of CO 2 , resulting in an improved description of these systems using VRM-G. Less promising results are obtained with VRM-L. VRM-L and VRM-G can describe benzene + 1-alkanol systems without cross-association. The quadrupolar models can qualitatively represent the VLLE of CO 2 + n-alkane and CO 2 + 1-alkanol systems. Good predictions of the CO 2 + benzene system are obtained with both VRM-L and VRM-G when only CO 2 is modeled as quadrupolar.

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SAFT-VR Mie is an established equation of state that offers excellent holistic descriptions of fluid behavior. However, the model does not account for the long-wavelength density fluctuations encountered in the critical region and can therefore not describe this region accurately. To this end, SAFT-VR Mie is treated with renormalization corrections, yielding SAFT-VR Mie + RG. This procedure is based on the ideas of White [J. Chem. Phys.199911193529356; J. Chem. Phys.200011232363244; J. Chem. Phys.200011315801586] where the fluid structure is incorporated into the renormalization corrections. SAFT-VR Mie + RG improves the description of pure-component properties in the critical region, without losing accuracy outside the critical region. The model is extended to mixtures using the isomorphism approach and applied to binary n-alkane systems. Remarkable predictions of critical loci are obtained without binary interaction parameters. SAFT-VR Mie + RG also describes the equilibrium phase behavior of these systems outside the critical region accurately, thus achieving the overarching aim of developing a model for global fluid phase equilibria.

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