Structure-based Generalized Models for Pure-fluid Saturation Properties and Activity Coefficients

Abstract

Structure-based generalized models were developed for a priori predictions of pure-fluid saturation properties, and for vapor-liquid equilibrium (VLE) of binary mixtures. Specifically, Quantitative Structure-Property Relationships (QSPR) modeling was used to provide structure-based parameters for (a) the Scaled-Variable-Reduced-Coordinate (SVRC) saturation property model, and (b) the Non-Random Two-Liquid (NRTL) and the Universal Quasi-Chemical (UNIQUAC) activity coefficient models. A representative database comprised of diverse molecular species was utilized for these generalizations. The SVRC-QSPR model generalizations for vapor pressure and saturated phase densities yielded predictions with absolute average deviation (AAD) of 1%. Similarly, the NRTL-QSPR and UNIQUAC-QSPR activity coefficient models produced VLE predictions within twice the AAD of the data regressions. The results of this preliminary study demonstrate the efficacy of using theory-framed QSPR modeling for generalizing saturation property and phase equilibrium models.