Phase Behavior Modeling of Mixtures Containing N-, S-, and O-Heterocyclic Compounds Using PC-SAFT Equation of State

Abstract

In this study, thermodynamic modeling of mixtures including heterocyclic compounds using the perturbed chain statistical associating fluid theory (PC-SAFT) equation of state (EoS) is studied. The oxygen-, nitrogen-, or sulfur-containing heterocyclic molecules are modeled as nonassociating components. For some more aggregative associating compounds with −OH (furfuryl alcohol, tetrahydrofurfuryl alcohol, 2-thiophenemethanol, and 5-hydroxymethylfurfural) or −NH (azetidine, aziridine, pyrrole, pyrazole, pyrrolidine, pyrrolidone, piperidine, morpholine, imidazole, piperazine, and n-methylpiperazine) groups, two association sites are considered for each molecule. The pure component parameters of the PC-SAFT EoS are adjusted to vapor pressure and liquid density experimental data with average absolute relative deviation of 0.88 and 0.77%, respectively. Using the obtained parameters, the isobaric and isothermal phase behavior of binary systems is studied over a wide range of thermodynamic conditions. The average deviations between model calculations and experimental data for heterocycle + aromatics, heterocycle + cycloalkane, heterocycle + haloalkanes, heterocycle + alcohol, heterocycle + heterocycle, heterocycle + organic solvents, and heterocycle + hydrocarbon systems are about 1.79, 2.15, 1.03, 1.68, 2.81, 1.24, and 1.81% respectively. Furthermore, the solid–liquid equilibria of heterocycle mixtures have been predicted by estimation of melting and eutectic points over a wide range of compositions. The second-order-derivative thermodynamic properties of heterocyclic compounds including speed of sound (us) and heat capacity (Cp) have been also predicted. The obtained results are in good agreement with the experimental data.