Separation of the cyclohexane-benzene mixture by the extractive distillation process using ethylene glycol as a solvent

Abstract

The importance of cyclohexane lies in the fact that it is the main precursor for the production of Nylon 6 and Nylon 6.6, two of the most important synthetic fibers. Cyclohexane (CHX) is produced by catalytic hydrogenation of benzene (BZ), where cyclohexane with benzene is obtained as a product. Since CHX and BZ have close boiling temperatures, and similar molecular structures, their separation by conventional binary distillation is complicated. Thus, ethylene glycol (EG) was selected as a solvent in an extractive distillation (ED) process for the separation of the CHX-BZ mixture in Aspen Plus V9®; where the use of ethylene glycol as a solvent allowed us to obtain cyclohexane and benzene with purities of 99.91 mol%. In addition, compared to the extractive distillation with heat integration (EDHI) process that uses [C5(MIM)2][NTf2]2 + H2O as a mass separation agent; the use of EG as a solvent promotes an energy decrease of 41.14%, a saving of 55.07% in the Total Annual Cost (TAC), and a decrease of 72.38% in CO2 emissions. These outcomes underscore the efficacy of ethylene glycol as a suitable solvent in the purification of the cyclohexane-benzene mixture.