(118o) Application of the GC-Saft-Vr Equation to Predict Fluid Phase Behavior

SAFT-VR is a widely used molecular-based equation of state
that has been successfully applied to study a wide range of fluid systems.  It provides a framework in which the
effects of molecular shape and interactions on the thermodynamics and phase
behavior of fluids can be separated and quantified.  In the original SAFT-VR approach, molecules were modeled as
chains composed of identical segments [1].  Hence the heterogeneity of molecules was described
implicitly through effective parameters. 
In a recent work, the GC-SAFT-VR [2] approach was developed to account
explicitly for the effects of molecular structure and composition. This
approach provides an excellent description of phase behavior of pure
non-associating fluids and mixtures, where the parameters for different key
functional groups (CH₃, CH₂, CH, CH₂=CH, C=O,
C₆H₅, CH₃O and CH₂O esters groups)
were obtained. In this work, we apply the CG-SAFT-VR approach to study the
phase behavior of associating systems such as alcohols, amines, aldehydes, and
acids, and their mixtures. New functional groups (OH, NH₂, CH=O,
COOH) are defined and their molecular parameters are characterized by fitting
to experimental vapor pressure and saturated liquid density data for selected
small molecules of different chemical families. Transferability of the
parameters is tested by comparing the theoretical predictions with experimental
data for pure fluids and binary mixtures not included in the fitting process.

1.   
Gil-Villegas, A., et al., Statistical associating fluid theory for chain
molecules with attractive potentials of variable range. Journal Of Chemical
Physics, 1997. 106,
4168-4186.

2. Peng, Y.; Goff, K. D.; dos Ramos, M. C.; McCabe, C. Submitted
to Fluid Phase Equilibria 2008