Modeling of Polar Systems with the Perturbed-Chain SAFT Equation of State. Investigation of the Performance of Two Polar Terms

Abstract

The Perturbed-Chain SAFT (PC-SAFT) equation of state is applied to model phase equilibria and the thermodynamic properties of ethers and esters. A systematic study of these two homologous series is conducted, and the performance of two different approaches for including the dipolar interactions in the equation of state is evaluated. Although both Polar PC-SAFT [dipolar contribution due to Jog and Chapman, Mol. Phys. 1999, 97, 307-319] and PC-SAFT + Fischer [dipolar contribution by Saager and Fischer, Mol. Simul. 1991, 6, 27-49] yield similar results for the considered systems, the parameters of Polar PC-SAFT are more physically meaningful than those of PC-SAFT + Fischer. Consequently, Polar PC-SAFT is considered to be more suitable for extrapolations, and for application to components that have multiple polar groups in the chain.

Application of GC-SAFT EOS to polar systems using a segment approach

“…As shown by earlier studies [1][2][3][4][5][6][7][8], polar and/or associative interactions to be taken into account to reproduce satisfactorily the shape of the phase diagrams.…”

“…Furthermore, a more predictive model (k ij = l ij = 0) may be thus obtained as demonstrated by Dominik et al [6] and Tumakaka et al [22]. Indeed, Jog et al [1] argued that, if the multipolar terms are neglected in the EOS, the polar interactions are effectively included in the van der Waals attractions, leading to overestimations of the energy parameter ε ij values.…”

“…Finally, in order to treat the dipolar interactions, we followed Chapman and co-workers [2,6] and introduced the fraction of dipolar segment in the chain of 1-alkanol as follows:…”

“…Steps forward into that direction have been done using polar versions of the SAFT EOS [1][2][3][4][5][6][7][8], but rarely in a predictive manner e.g. using a group contributions (in references [9,10] one founds the first attempts to develop such a method in SAFT EOS).…”

Prediction of binary intermolecular potential parameters for use in modelling fluid mixtures

“…By contrast, many workers e.g., Refs. [16,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52] have adopted the explicit approach, i.e., a polar contribution is explicitly included in the free-energy expression. Explicit incorporation of the polar interactions in the theoretical description may be viewed as more rigorous and there are a number of further advantages associated with this approach.…”