Heterogeneous batch‐extractive distillation of minimum boiling azeotropic mixtures

Abstract Following previous studies on heterogeneous batch azeotropic distillation, the use of heterogeneous entrainers for the separation of binary azeotropic mixtures by extractive distillation is evaluated. This process is well suited for systems where the entrainer forms a saddle heteregeneous azeotrope with any one of the original components, such systems being unsuitable for nonextractive heterogeneous batch‐distillation processes. Process feasibility is assessed from the isovolatility curves and the volatility order diagram. It tells us whether the homogeneous original component or the heteroazeotrope is drawn at the column top and establishes the distillation tasks sequence using a batch‐rectifying column. The theoretical insights are validated via rigourous simulation for the separation of the acetonitrile–water mixture with hexylamine or butyl acetate. Finally, the same method is applied for the theoretical analysis of a reported industrial example where water is used for the separation of a binary organic mixture, leading to a complex ternary system with several binary azeotropic points and a homogenous ternary azeotrope.