Development of a Universal Group Contribution Equation of State III. Prediction of Vapor−Liquid Equilibria, Excess Enthalpies, and Activity Coefficients at Infinite Dilution with the VTPR Model

Abstract

The well-accepted PSRK prediction method is a suitable tool for industrial applications, especially if no reliable experimental data are available. Because this model still contains a few weaknesses, a more powerful group contribution equation of state called VTPR was developed to replace the PSRK model. A volume-translated Peng−Robinson (PR) equation of state (EOS), connected with the residual part of the group contribution method UNIFAC by means of a simple gE mixing rule, provides reliable predictions of vapor−liquid equilibria over wide temperature and pressure ranges. Furthermore, in combination with a nonlinear quadratic b mixing rule, this group contribution equation of state (GCEOS) provides very good predictions of asymmetric systems. The use of a volume-translated Peng−Robinson EOS significantly improves the description of liquid densities of pure compounds and mixtures in comparison to that obtained with the Soave−Redlich−Kwong EOS, which is used in the PSRK model. In this part of our development of the VTPR approach, group interaction parameters are given that are fitted simultaneously to experimental vapor−liquid equilibria data, activity coefficients at infinite dilution, and excess enthalpy data, which are stored in the Dortmund Data Bank (DDB). Furthermore, results for compounds with main groups alkanes, nonalkylated aromatics, ketones, CO2, and CH4 are compared with the results obtained using the PSRK model.