Lecture 5

Question 1

What are the main types of enzymatic reactors?

Answer 1

• Batch
• Fixed bed PFR
• Fluidised bed
• Membrane reactors

Question 2

Briefly describe each type

Answer 2

• Batch
- Simple batch = lab scale, inexpensive and rapidly deactivating biocatalysts
- Batch UF = UF (ultrafiltration) after batch if biocatalyst to be recycled
· Fixed bed PFR
- Single passage = used with enzymes immobilised on support beads that are packed to form fixed bed => undesired radial and axial gradients occur
- Recycle (loop) - conversion increased with increased no.of.passages => consumes more energy due to higher fluid velocities
· Fluidised bed
- Minimises undesired radial and axial pH/temp gradients => difficult to control compared to fixed bed
· Membrane reactors
- CSTR with dead-end filtration = membrane retains biocatalyst but allows products and substrates to pass => has size specific pores => dead-end filtration mode
- Recycle (loop) with tangential filtration = membrane retains biocatalyst but allows products and substrates to pass => has size specific pores => tangential filtration mode