Module 4 Lesson 3 Flashcards
About commercial value of enzymes is associated to its enormous applications as biocatalysts
80%
are vessel employed to carry out the desired conversion of raw materials using enzymes
Enzyme reactors
Batch processes with the enzymes, commonly Blank, dissolved in an aqueous reaction medium have several disadvantages
hydrolases
In the Blank, the enzymes are poorly stable and hard to recover in such systems and it leads to low productivity.
batch process
is usually the limiting factor in any enzyme process.
Poor stability
is the most relevant strategy for enzyme stabilization
Enzyme immobilization
Why industry has been reluctant to adopt it?
Because of the costs associated to process control and yield losses during immobilization and mass transfer limitations during operation have prevented a more extended use of immobilized enzymes as process biocatalysts.
What are the Basic design of Enzyme Reactors under Ideal conditions?
Batch Enzyme Reactor
Continuous Packed Bed Reactor
Continuous Stirred-tank Reactor
This enzyme reactor is discontinuous.
The reactor is filled with the reaction medium containing the substrates and operating conditions is adjusted.
The enzyme is added and the reaction is left to proceed until the desired conversion has been obtained
Large agitated tanks in which enzyme and substrate are placed.
This is suitable for cheap enzymes
Risk of enzyme destruction during recovery process.
Batch Enzyme Reactor
This operation is continuous with a constant flowrate of reaction medium fed to the reactor where the biocatalyst is packed forming a submerged bed.
Continuous Packed Bed Reactor
Continuous Packed Bed Reactor can be fed from the blank or the blank
Bottom or Top
At laboratory scale it is often ideal to use Blank for easy maintenance of the liquid level above the biocatalyst bed
bottom feeding
At large scale Blank is frequently used to reduce the energy requirements for pumping.
Bed compaction can be regulated in this case
top feeding
This is a continuous operation with a constant flowrate of reaction medium fed to the reactor where the enzyme is suspended in an agitated vessel.
If well mixed, any element of fluid within the reactor has the same composition, corresponding to reactor outlet.
All enzyme in this case, are in contact with the same, corresponding to its outlet value, which is quite different than in CPBR (continuous packed bed reactor).
Continuous Stirred-Tank Reactor
Compare and contrast the Continuous packed bed reactor and the Continuous stirred-tank reactor
The Continuous Stirred-Tank Reactor (CSTR) operates with a constant flow rate and uses an agitated vessel to suspend enzymes, ensuring uniform mixing. All enzyme contact occurs with a composition matching the reactor outlet, which differs significantly from the composition gradient in a Continuous Packed Bed Reactor (CPBR). In contrast, the CPBR uses a packed bed of biocatalyst with constant flow, fed from the bottom at the lab scale to prevent bed compaction or from the top at larger scales to reduce pumping energy. Flow reversal in CPBR aids in cleaning and compaction regulation. While CSTR ensures uniformity, CPBR achieves steady-state after several residence times and is better suited for continuous, steady operations.
