Dehydration of isopropanol by batch heteroazeotropic distillation with toluene as entrainer

The dehydration of isopropanol (B) by batch heteroazeotropic distillation (BHAD) is studied by dynamic simulation. The mixture also contains methyl ethyl ketone (A) and toluene (E) as pollutants. The water (C) content of the feed (ca. 2 mass%) is much lower than that of the B-C azeotrope. B can be obtained as residue by conventional batch distillation (BD) under a very high reflux ratio and considerable loss of B, only. The loss of B can be considerably decreased by BHAD. Toluene, already present in the mixture, can be a suitable entrainer (E), since it forms a ternary heteroazeotrope with isopropanol and water. Dehydration is feasible by Mode II, Strategy A of BHAD, that is, the two liquid phases of the condensate are separated in a decanter, and the whole amount of E-rich phase is refluxed, while that of E-lean phase is withdrawn as distillate. As the production is very slow because of the high (E-rich/E-lean) phase ratio, several operational strategies are studied in order to make it faster. These include taking a homogeneous fore-cut to remove methyl ethyl ketone, and Strategy B of Mode II, where part of the E-rich phase is also taken as distillate. © Copyright 2018, AIDIC Servizi S.r.l.