Recycling of immobilized enzymes using rotating bed reactor technology

Widespread industrial usage of enzymes has been hampered by a number of challenges relating to the separation of the enzyme from the batch. By immobilizing the enzyme onto a solid carrier material, separation is simplified and the stability enhanced. However, when used in traditional stirred tank reactors (STR) or fixed bed reactors (FBR), other problems consequentially arise:

• STR: Catalyst activity is lost between batches due to mechanical damage to the particles
• FBR: Substrates (e.g. with high viscosity) are difficult to pump through fixed bed reactors at sufficient rates

The solution to reusing the catalyst for many batches, and still keeping the productivity high, is spelled ‘rotating bed reactor’, or RBR for short. With an RBR, the separation of the solids from the product is intrinsic to the reaction and no additional unit operation is required to capture the catalysts. Additionally, the RBR is very robust to high viscosity, practically handling all relevant substrates.

Plot of relative amount of substrate (grey) and product (blue) during 4h batch cycles with the same immobilized enzyme (Purolite CalB immo Plus lipase

This poster, presenting data from several laboratories, looks at three esterification and transesterification reactions. Considerable increases in reaction rate were accomplished by using the rotating bed reactor at a higher rotational speed. The tests also showed that no attrition or grinding occurred and that no filtration was necessary between reaction cycles. The production capacity was estimated to 50,000 grams of product per gram of catalyst, thanks to the high catalyst stability.

• Fast reaction rates
• Excellent catalyst stability
• High production capacity

The combination of high catalyst stability and streamlined recycling enables automated semi-continuous processes with greatly improved production economy.

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