Integration of Enzymatic Catalysts in a Reactive Distillation Column with Structured Packings

Abstract

The integrated process setup of reaction and separation in reactive distillation can be favorable for enzyme-catalyzed reactions that are often equilibrium-limited and/or inhibited by the product of the reaction. However, until now, no appropriate way has described the implementation of the enzymes into distillation columns. In this work, a special type of biocatalytic coating for commercially available structured packings was developed to enable enzymatic reactions in reactive distillation columns. Lipase CALB was immobilized within the silica-gel based coating and showed high long-term stability, i.e., the coatings can be stored for at least 50 days at room temperature without any significant loss of enzyme activity. In addition, the silica-gel coatings were stable in organic media and at increased temperatures. Reactive distillation experiments were carried out in a batch reactive distillation setup comprising of structured A3-500 packings from Montz (Hilden, Germany) coated with the catalytic silica gel. Stepwise removal of the low boiling point product from the distillate shifted the equilibrium to the product side and increased the conversion of the reactants from 60% to 98%, in comparison with the corresponding setup in a standard batch reactor. The stability of the silica-gel coating and loss of the enzyme was investigated during the distillation runs. Overall, the integration of an enzymatic reaction into a reactive distillation column offers new possibilities for the application of biocatalysts in organic synthesis.