Simulation studies on extractive distillation of BTX mixtures using DMSO and sulfolane with ASPEN HYSYS

Benzene, Toluene, and Xylene (BTX isomers) are significantly vital fundamental chemicals for petrochemical, oil, and gas industries with global production amounting to about 40 MMT per annum for Benzene and Xylene while around 20 MMT for toluene. BTX as initiators for downstream derived commodities are produced from coking and petroleum naphtha and pyrolysis gasoline by hydro-treatment and catalytic reforming processes. The present work focuses on ASPEN simulation for BTX separation via conventional distillation and extractive distillation routes. For the extractive distillation (ED) process, two different solvents – Dimethyl Sulfoxide (DMSO) and Sulfolane were employed to estimate the purity of separated components from the mixture as well as the recovery percentage of solvent for reuse potential. Extractive distillation processes are widely adopted for isolating aromatic and non-aromatic hydrocarbons. Solvents employed in ED typically aid in separation due to close boiling points and azeotropic compositions of mixtures. Maximum purity of components at 97.91 % Benzene, 98.27 %Toluene, and 96.88% o-Xylene were obtained after separation with 98.33% solvent recovery using sulfolane as solvent. Amongst various dipolar aprotic solvents like DMF, DMAC, NMP, and DMSO, sulfolane is also known to offer appreciable thermal stability. Sulfolane also possesses attractive properties such as high selectivity, high boiling point, and high dissolution capability.