Reactive distillation
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Reactive distillation is a process where the chemical reactor is also the still. Separation of the product from the reaction mixture does not need a separate distillation step, which saves energy and materials. The combination of chemical reaction with distillation in only one unit is called reactive distillation. The performance of reaction with separation in one piece of equipment offers distinct advantages over the conventional, sequential approach. Especially for equilibrium limited reactions such as esterification and ester hydrolysis reactions, conversion can be increased far beyond chemical equilibrium conversion due to the continuous removal of reaction products from the reactive zone. This may lead to an enormous reduction of capital and investment costs and may be important for sustainable development due to a lower consumption of resources.
Benefits
- Increased speed and improved efficiency
- Lower costs – reduced equipment use, energy use and handling
- Less waste and fewer byproducts
- Improved product quality– reducing opportunity for degradation because of less heat exposure.
Difficulties
However, the conditions in the reactive column are suboptimal both as a chemical reactor and as a distillation column, since the reactive column combines these. Furthermore, the interdependence of distillation and reaction makes control difficult, and the feedback is nonlinear. In practice, it is necessary to create reliable simulations.Side reactors, where a separate column feeds a reactor and vice versa, are better for some reactions, if the optimal conditions of distillation and reaction differ too much.
Setup
Typically, reactive distillation equipment comprises a reactive column, with the feed input, with directly attached stripping and enriching columns with the outputs.Applicable Processes
Reactive distillation can be used with a wide variety of chemistries, including the following:
- Acetylation
- Aldol condensation
- Alkylation
- Amination
- Dehydration
- Esterification
- Etherification
- Hydrolysis
- Isomerization
- Oligomerization
- Transesterification
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