A systematic investigation of microwave-assisted reactive distillation: Influence of microwaves on separation and reaction

• Microwave-assisted evaporation leads to superheating of liquids.
• Microwaves do not enhance the separation efficiency in distillation.
• The performance of reactive distillation could not be improved by microwaves.

Reactive distillation is the integration of reaction and distillation into one apparatus enabled by a matching operating window. New ways of altering operating windows of both reaction and distillation could expand the application of reactive distillation in industry. Recent research results indicate that microwave irradiation might affect the thermal separation of molecules and accelerate chemical reactions. These two effects on improving the performance of reactive distillation for the homogeneously catalyzed transesterification of dimethyl carbonate with ethanol are investigated in this paper. Preliminary experiments on microwave-assisted evaporation of the pure components were conducted, in which relatively small superheating of the liquid phase is observed. Subsequently, conventional and microwave-assisted distillation of binary mixtures were compared. The experimental results indicate that there is no evidence for the influence of the applied microwave field on the separation of the investigated binary mixtures, since no enhancement of separation efficiency at the macroscopic distillation scale was observed. To study whether the performance of the reactive distillation process could be influenced by the reaction rate acceleration, due to the superheating of liquid phase observed in the experiments, a model-based process analysis was performed. The simulation results show neither significantly enhanced conversion nor selectivity.