Extension of the PPR78 model (predictive 1978, Peng–Robinson EOS with temperature dependent kij calculated through a group contribution method) to systems containing aromatic compounds

Abstract

In a previous paper [J.N. Jaubert, F. Mutelet, Fluid Phase Equilib. 224 (2004) 285–304], 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). In this approach, the k ij between two components i and j is a function of temperature ( T) and of the pure component critical temperatures ( T c i and T c j ), critical pressures ( P c i , P c j ) and acentric factors ( ω i , ω j ). 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 paper, six groups were defined: CH 3, CH 2, CH, C, CH 4 (methane) and C 2H 6 (ethane). It was thus possible to estimate the k ij for any mixture of saturated hydrocarbons ( n-alkanes and branched alkanes), whatever the temperature. In this study, the PPR78 model is extended to systems containing aromatic compounds. To do so, two new groups were added: CH aro and C aro.