Predicting the phase equilibria of CO 2 + hydrocarbon systems with the PPR78 model (PR EOS and kij calculated through a group contribution method)

Abstract

In 2004, we started to develop a group contribution method aimed at estimating the temperature dependent binary interaction parameters ( k ij ( T)) for the widely used Peng–Robinson equation of state (EOS). Because our model relies on the Peng–Robinson EOS as published by Peng and Robinson in 1978 and because the addition of a group contribution method to estimate the k ij makes it predictive, this model was called PPR78 (predictive 1978, Peng Robinson EOS). In our previous papers eleven groups were defined: CH 3, CH 2, CH, C, CH 4 (methane), C 2H 6 (ethane), CH aro, C aro, C fused aromatic rings, CH 2,cyclic and CH cyclic C cyclic. It was thus possible to estimate the k ij for any mixture containing alkanes, aromatics and naphthenes at any temperature. In this study, the PPR78 model is extended to systems containing carbon dioxide. To do so, the group CO 2 was added. The results obtained in this study are in many cases accurate.