Cumene extraction separation from alkanes using DMSO: Influence of the alkane structure

ABSTRACT In this study, the liquid-liquid equilibrium of dimethyl sulfoxide (DMSO)-cumene-alkanes (including n-alkanes and cycloalkanes) systems are measured at 30°C under atmospheric pressure. Following NRTL/UNIQUAC activity coefficient model correlation and the Gibbs energy minimization test are conducted. Moreover, the influence of alkane structure on the extraction results is elaborated. Finally, a set of wave function analyses are enacted to visualize the intermolecular interactions and quantify the physical contribution of different intermolecular effects. These investigations show that: The distribution coefficient and overall selectivity of cumene escalate with the increase of molecular weight, for both linear and cyclic alkane homologues. Meanwhile, the entrainment of alkane in the extraction phase decreases. The aromatic selectivity coefficient β for cycloalkane systems is lower than linear n-alkane with similar carbon number, regardless of more extracted model oil, which owes to high entrainment. The aromatic distribution coefficient Kar for cycloalkanes rises faster and eventually surpasses that of n-heptane system in terms of absolute value, which is verified by UNIFAC simulation. The interactions between cumene and n-alkanes/cycloalkanes are van der Waals interaction, driven by dispersion (70.10∼71.50%) and electrostatic (23.58∼24.66%) effect. As the molecular weight of the alkane increases, the dispersion contribution decreases, while the electrostatic interaction increases.