Application of CP-PC-SAFT and PC-SAFT for Simultaneous Prediction of LLE and High-Pressure VLE with Universal k₁₂ Values: II. Systems of Gases and Aliphatic Hydrocarbons with O-, S-, and N-Heterocyclic Compounds

This work continues a series of studies examining the reliability of critical point-based perturbed-chain statistical association fluid theory (CP-PC-SAFT) and PC-SAFT EoS models with universal k₁₂ values (0.023 and 0.017, respectively) for predicting vapor-liquid equilibrium (VLE) and liquid-liquid equilibrium (LLE) in systems of gases and aliphatic hydrocarbons with substituted aromatics and heterocyclic compounds. This time, systems of pyrrole, furan, tetrahydrofuran, thiophene, 1,4-dioxane, tetrahydrothiophene, γ-valerolactone, 2,3-benzofuran, and sulfolane are considered. It is found that PC-SAFT is usually more accurate than CP-PC-SAFT in modeling vapor pressures but inferior in estimating densities and sound velocities. The relation of the latter result to the additional fictitious critical point predicted by PC-SAFT is discussed. PC-SAFT is typically less accurate than CP-PC-SAFT in predicting the high-pressure VLE in the systems of gases. Due to rigorous obedience of pure compounds' T_c and P_c, CP-PC-SAFT has an obvious advantage in predicting the critical VL data. At the same time, PC-SAFT is somewhat more accurate in estimating VLE in butane and butene isomer systems. The CP-PC-SAFT predictions for LLE in systems of n-alkanes with pyrrole and γ-valerolactone continue the patterns found in the previously discussed cases. In particular, it accurately estimates upper critical solution temperatures (UCSTs) and compositions of heterocyclic compound-rich phases but deviates from the data of n-alkane-rich ones. PC-SAFT underestimates UCSTs and yields poorer results for both LLE phases. The considered models comparably predict binary LLE in n-alkane-sulfolane systems. CP-PC-SAFT is generally superior to PC-SAFT in evaluating LLE in the considered aliphatic-aromatic-heterocyclic ternary systems. Based on the findings of this study, it can be concluded that both models with the universal k₁₂ values can be used for preliminary evaluation of inaccessible data on phase equilibria in a large number of systems including gases and aliphatic hydrocarbons with heterocyclic compounds. CP-PC-SAFT may be more reliable in estimating LLE and high-pressure VLE, while PC-SAFT may be more accurate in predicting low-pressure VLE data.