Design and optimization of batch reactive distillation processes with off-cut

• We find optimal operating policies for batch reactive distillation with off-cut.
• Incorporating off-cut can significantly improve process performance.
• Process design depends on normal boiling point ranking of reactants and products.
• Off-cut is more desirable when process operation is more difficult.

Although off-cut is commonly applied in non-reactive batch distillation, reports of the application of off-cut for batch reactive distillation (BREAD) are quite rare. In order to systematically investigate the use of off-cut in BREAD systems, we develop the optimal BREAD process design with and without off-cut for a canonical set of hypothetical reaction systems and a process for the hydration of methyl lactate. The results show that using off-cut can significantly improve performance, especially when both reactants have boiling points between those of the two products (for a quaternary system), when the product purity specification is high, and when the reaction equilibrium constant is low. The optimal batch recipe including off-cut can also be understood based on the normal boiling point ranking of the reactants and products.