Comparison of SAFT-VR-Mie and CP-PC-SAFT in predicting phase behavior of associating systems IV. Methanol–aliphatic hydrocarbons

This study compares the predictions of CP-PC-SAFT and SAFT-VR-Mie for the binary systems of methanol with aliphatic hydrocarbons in a wide range of conditions. For each of the models, a universal value of the binary adjustable parameter k₁₂ was fitted to just one experimental datum; namely, the UCEP of n-butane(1) – methanol(2). The resulting model-specific values were implemented for predicting the entire available LLE data in other homologues until n-decane, the critical loci from methane and till n-hexatriacontane, along with the relevant VLE. With these methodologies, 3 association kernels of SAFT-VR-Mie attached by 8 sets of pure compound parameters yielded particularly poor estimations of the LL critical loci in the n-alkane–methanol series of systems. The same can be concluded in the cases of some additional SAFT-VR versions, SAFT-HR, and soft-SAFT. Unlike these, the relevant results of PC-SAFT approaches in general are reasonably good, while those of CP-PC-SAFT are surprisingly accurate. In addition, the rigorous obeying of the pure compound T_c and P_c makes CP-PC-SAFT advantageous in predicting the VL critical loci and phase equilibria in the asymmetric systems of methanol. However, its performance in estimating VLE of the more symmetric systems becomes comparable to SAFT-VR-Mie. In addition, CP-PC-SAFT is superior in estimating the excess enthalpies.