Revisiting the treatment of cross-association interactions in oxygenate mixtures with the polar PC-SAFT equation of state

In this work a new approach to the cross-association of non-self-associating (NSA) oxygenates with carbonyl oxygens within polar PC-SAFT is developed. Aldehydes, esters and ketones fall into this class of NSA molecules. The challenge in developing such an approach is that predictability of phase behavior of NSA species with alcohols is desired, while at the same time, there is the requirement that the approach must be able to reproduce the phase behavior in aqueous systems. To meet these two criteria, the hydrogen bonding parameters of the NSA oxygenate are adjusted to accurately reproduce the phase behavior with water. With the hydrogen bonding parameters fixed, binary interaction parameters between NSA oxygenates and alcohols must be adjusted to achieve accurate phase behavior. However, as shown in this work, these binary interaction parameters are predictable solely on the basis of alcohol and NSA oxygenate molecular weights. A simple correlation of the binary interaction parameter between these two classes is developed, allowing for accurate representation of the phase behavior with alcohols in absence of phase behavior data to tune the model.