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We have recently received reports that some of our customers are being told catalyst can be regenerated to last for several years. Advice being received by some customers is causing them to believe that drying out catalyst on a regular basis will increase its lifespan. This is not true and customers may be putting their samples at risk if following that advice.
The facts
Strict anaerobic growth conditions are maintained within anaerobic workstations when a catalytic reaction takes place between any oxygen in the workstation atmosphere and hydrogen contained within the anaerobic gas mixture. Water is produced as the by-product of catalytic activity and a reasonable level of humidity in the workstation atmosphere is useful. However, catalyst performance is adversely affected if moisture is allowed to form on the catalyst.
Wet catalyst can be dried out in a warm oven but this will not extend the life of the catalyst indefinitely. This drying process will remove excess moisture and may provide some short-term revitalisation of catalyst performance.
Catalyst life depends upon many factors. Drying a catalyst cannot prevent irreversible poisoning of the catalyst due to sulphur and chlorine compounds, oil, unsaturated hydrocarbons and the vapours of some organic solvents. Catalyst poisons also include the products of metabolism of some anaerobes.
Our recommendations
If you have a Whitley Workstation there are several safeguards already in place to help optimise the life of your catalyst:
- Sachets of Anotox™ (exclusive to Don Whitley Scientific) are used in conjunction with the catalyst to reduce the quantity of volatile fatty acids and hydrogen sulphide present in the workstation atmosphere. These substances are the product of metabolism of some anaerobes and not only contribute to catalyst poisoning but can have an adverse effect on the growth of some anaerobes.
- Catalyst and Anotox™ are positioned inside every Whitley Workstation in locations that enable warm internal atmosphere to pass over them continuously, virtually eliminating any risk that catalyst will get damp.
- The Whitley Automatic Dehumidifier is fitted as standard to all Whitley Workstations and automatically removes any water vapour surplus to requirements. This device also helps prevent the catalyst getting damp in the first place.
- Whitley Anaerobic Conditions Monitor. This optional feature, available for some Whitley Workstations, indicates whether suitable anaerobic conditions exist and provides an early warning if conditions begin to vary.
- When you have a Whitley service contract, both the catalyst and Anotox™ are changed every 6 months to ensure you continue to achieve stable, reliable anaerobic conditions.
Don Whitley Scientific recommends replacing catalyst annually and, if you have a Whitley Workstation, at the same time as replacing the Anotox™ compound.
In summary
It is not possible to prolong the life of catalyst indefinitely by simply drying it out. Drying cannot reverse the effects of natural catalyst poisoning. If you replace your catalyst on a regular basis you will ensure strict anaerobic conditions are maintained and reduce the risk of adversely affecting your samples.
If you have any further questions about catalyst life or the use of Anotox™ please give us a call on 01274 595728 or email sales@dwscientific.co.uk
Anotox™ is a trademark of Don Whitley Scientific Limited.
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