Comparison of batch heteroazeotropic distillation operational strategies for the dehydration of isopropanol

The dehydration of isopropanol (B) from a mixture containing methyl ethyl ketone (A) and toluene (E) as pollutants by batch heteroazeotropic distillation (BHAD) is studied by dynamic simulation. The water (C) content of the feed is much lower than that of the BC azeotrope. Isopropanol can be obtained by conventional batch distillation under high reflux ratio and considerable loss. Toluene is a potential entrainer forming a ternary heteroazeotrope BCE. Dehydration is feasible by Mode II, Strategy A of BHAD, by which the whole amount of E-rich phase is refluxed, that of E-lean phase is withdrawn as distillate. Since the production is very slow due to the high (E-rich/E-lean) phase ratio, different operational strategies are studied in order to make the production faster without significant decrease in isopropanol recovery. These include taking a homogeneous fore-cut to remove methyl ethyl ketone, and Strategy B of Mode II, where one part of the E-rich phase is also withdrawn as distillate. A novel operational policy is proposed, as well, that is a combination of Strategies A and B. The application of cyclohexane (D) as entrainer and batch extractive distillation with dimethyl sulfoxide (F) are also studied.