(88e) A Reactive Distillation Column with Two Reaction Zones for the Cyclohexanol Production from Cyclohexene

Reactive distillation columns can render great advantages in capital investment and operating cost over the conventional reactor/separator/recycle systems for some simple reaction operation and separation operation. In the case of the separations of some complicated reacting mixtures including multiple step reactions, a train of reactive distillation columns is frequently needed. Although such kind of systems can still present superior performance in comparison with their conventional counterparts, it is likely to go further in seeking the potential of process intensification. It is noted that In addition to multiple condensers and reboilers, outlet and inlet streams, and possible recycle streams, each reactive distillation column involved carries out only one reaction operation and separation operation. These points remind us of arranging multiple reaction and separation operations in a single reactive distillation column and this leads to a reactive distillation column with multiple reaction zones. Steyer et al (2008) mentioned the possibility for the indirect hydration of cyclohexene to cyclohexanol with formic acid as a reactive entrainer. However, they did not report further outcomes on process synthesis, design and operation. Katariya et al. (2009) simulated a coupled reactive distillation column for the cyclohexanol production from cyclohexene and gave its optimum process design.

In terms of thermodynamic characteristics of reaction operation and separation operation involved, a reactive distillation column with two reaction zones is proposed for the production of cyclohexanol by indirect hydration of cyclohexene. The arrangement of two separate reaction zones not only allows the careful coordination of the two reaction operations involved, but also provides additional degrees of freedom for the reinforcement of internal mass integration and/or internal energy integration between the reaction operations and the separation operation involved. Through intensive comparison between the reactive distillation column with two reaction zones and the coupled reactive distillation columns, it is demonstrated that the former could lead to reduced total annual cost in comparison with the latter. The reactive distillation column with two reaction zones should therefore be considered as a competitive alternative to the coupled reactive distillation columns for the production of cyclohexanol by indirect hydration of cyclohexene.

References

Steyer F., Freund H., Sundmacher K., 2008, A novel reactive distillation process for the indirect hydration of cyclohexene to cyclohexanol using a reactive entrainer, Ind. Eng. Chem. Res. 47, 9581-9587.

Katariya A., Freund H., Sundmacher K., 2009, Two-step reactive distillation process for cyclohexanol production from cyclohexene, Ind. Eng. Chem. Res. 48, 9534-9545.