Quantitative comparison between predicted and experimental binary n-alkane + benzene phase behaviors using cubic and PC-SAFT EOS

Bubble Pressure Measurement and Prediction for n-Hexadecane and n-Eicosane + Cyclohexane, Methylcyclohexane, and Ethylcyclohexane Binary Mixtures from 303.15 to 393.15 K

“…The regressed k ij values are negative for all six mixtures, which opposes the conventional assumption of either k ij = 0 for hydrocarbon−hydrocarbon mixtures or is a small but positive value obtained from correlations 16,17 commonly used in process simulators for such mixtures. This observation is in line with our previous findings, 14 which focused on n-alkane + aromatic binary mixtures.…”

“…As discussed in detail in two previous works, 13,14 selection of the EOS binary interaction parameter (k ij ) values for asymmetric hydrocarbon mixtures (such as the ones studied in this work) can have a significant impact on the accuracy of phase behavior predictions obtained from equations of state, especially cubic EOS. k ij values for the six binary mixtures tested in this work were regressed using the bubble pressure data in Table 4.…”

“…16,17 Such conventional assumptions frequently lead to unrealistic liquid−liquid phase behavior predictions for mixtures comprising aromatics and naphthenes + alkanes (n-C 20 +) at lower temperatures and significant overprediction of mixture bubble pressures at higher temperatures. 13,14 Experimental phase equilibrium data for such asymmetric mixtures are needed to test existing correlations and/or development of new correlations for reliable estimation of k ij values.…”

“…Two of the most commonly used cubic equations of state (EOS), Peng–Robinson and Soave–Redlich–Kwong, systematically predict qualitatively and quantitatively incorrect phase behaviors for long-chain n -alkane + aromatic and naphthenic mixtures unless negative k ij values are used. , Type II vs Type I phase behavior (according to the van Konynenburg and Scott naming scheme) is predicted. Binary interaction parameters are typically obtained by fitting vapor–liquid equilibrium (VLE) data for binary mixtures.…”

“…In the absence of data, interaction parameter values are obtained from generalized correlations or are set to zero for hydrocarbon–hydrocarbon binaries. Correlations commonly used in process simulators provide small positive values for long-chain n -alkane + aromatic and naphthenic mixtures. , Such conventional assumptions frequently lead to unrealistic liquid–liquid phase behavior predictions for mixtures comprising aromatics and naphthenes + alkanes ( n -C 20 +) at lower temperatures and significant overprediction of mixture bubble pressures at higher temperatures. , Experimental phase equilibrium data for such asymmetric mixtures are needed to test existing correlations and/or development of new correlations for reliable estimation of k ij values.…”