Efficient separation method for tert-butanol dehydration via extractive distillation

Separation of tert-butanol and water is an important task in the co-oxidation process of propylene/isobutane. These two compounds form minimum-boiling azeotrope which cannot be separated by simple distillation. In this paper, an efficient separation method for tert-butanol dehydration via extractive distillation is investigated. The heavy entrainer used is glycerol, a non-toxic byproduct in the production of biodiesel, is less expensive and more environmentally friendly than other conventional entrainers. By comparing the optimized design of this extractive distillation system with a recently published heterogeneous azeotropic design, significant reductions of 57.5% in the steam cost and 43.7% in the total annual cost can be obtained. In order to further save energy, a feed-effluent heat exchanger can be added in the proposed extractive distillation system. With this simple heat-integration design, a further 15.9% reduction in steam cost and 11.7% in total annual cost can be made as compared to the original one.