VLE predictions with the Peng–Robinson equation of state and temperature dependent kij calculated through a group contribution method

A group contribution method allowing the estimation of the temperature dependent binary interaction parameters (kij(T)) for the widely used Peng–Robinson equation of state (EOS) is proposed. A key point in our approach is that the kij between two components i and j is a function of temperature (T) and of the pure components critical temperatures (TCi and TCj), critical pressures (PCi, PCj) and acentric factors (ωi, ωj). This means that no additional properties besides those required by the EOS itself (TC, PC, ω) are required. 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 kij makes it predictive, we decided to call this new model PPR78 (predictive 1978, Peng–Robinson EOS). s paper six groups are defined: CH3, CH2, CH, C, CH4 (methane), and C2H6 (ethane) which means that it is possible to estimate the kij for any mixture of saturated hydrocarbons (n-alkanes and branched alkanes), whatever the temperature. sults obtained in this study are in many cases very accurate and often better than those obtained with the best EOS/gE models. In particular, it is shown that asymmetric systems can be accurately predicted with our model. Some comparisons are given with the LCVM model.