Prediction of the phase behavior of alkene-containing binary systems with the PPR78 model

The study of the phase equilibria of alkene-containing mixtures is fundamental to the petroleum and chemical industries. Therefore, the development of a predictive model for these systems is a necessary and challenging task. The PPR78 (predictive 1978, Peng–Robinson EoS) model is a predictive thermodynamic model that combines the widely used Peng–Robinson equation of state and a group contribution method aimed at estimating the temperature-dependent binary interaction parameters, kij(T), involved in the Van der Waals one-fluid mixing rules. In our previous papers, sixteen groups were defined: CH3, CH2, CH, C, CH4 (methane), C2H6 (ethane), CHaro, Caro, Cfused aromatic rings, CH2,cyclic, CHcyclic ⇔ Ccyclic, CO2, N2, H2S, SH and H2. It was thus possible to estimate kij for any mixture containing alkanes, aromatics, naphthenes, CO2, N2, H2S, mercaptans and hydrogen regardless of the temperature. In this work, four alkene groups are added in order to accurately predict not only the mutual solubility of petroleum components and alkenes but also the critical loci of binary alkene-containing systems.