Non-thermal catalysis

Long-lasting, effective technology

Non-thermal catalysis technology is the result of combining three technologies:

  • Trapping contaminants using specific adsorbents.
  • Destruction by a light-activated catalyst.
  • Treatment completed by a catalyst which is active at ambient temperature.

The catalysts regenerate thus ensuring long-lasting air handling efficiency.

Our technology is also energy-efficient.

 

Focus on non-thermal catalysis: the heart of our technology.

Non-thermal catalysis is a technology developed by our laboratory which traps and destroys microbiological and chemical contaminants. The technique is based on a synergetic combination of three components (an adsorbent and two catalysts) on the same material.

Firstly, the adsorbent acts as a “sponge”, capturing and retaining the contaminants on its surface.

They are then naturally transferred to the catalysts which destroy them by redox reactions. The catalysts are of two types, on the one hand a catalysts which is active at ambient temperature, and on the other a light-activated catalyst. Their action is different but complementary.

The light-activated catalyst very effectively destroys micro-organisms (fungi, spores, bacteria, viruses) and gases such as odours and volatile organic compounds (VOC).
The catalyst active at ambient temperature completes the process by guaranteeing the destruction of the contaminants until they are completely broken down into infinitesimal amounts of water vapour, water and carbon dioxide (CO2).

Materials used:
There are different sorts of adsorbent. The best-known and most commonly used for air treatment are active carbon and zeolites. Zeolites (natural or synthetic) offer the particular advantage of being highly selective with regard to the contaminants. This is why we opted for this material. Hydrophilic zeolites are useful in that they have a particular affinity for microbial cell membranes and also for chemical pollutants often present in indoor air.

Some zeolites even go beyond simply being adsorbent and are also toxic to micro-organisms. This is the case of some type A synthetic zeolites, impregnated or doped zeolites.

In addition to their composition, the size of zeolites is also important. While numerous publications focus on very small sized materials (nanoparticles), the latter are increasingly heavily criticised due to their dangerous nature and the strong suspicion that they are carcinogenic. On the contrary, in the case of zeolites with an affinity for micro-organisms, some studies tend to prove that the most effective ones are between 0.5 and 2.5 microns in size, which is at least five times larger than the size below which a particle is considered to be nanometric (0.1 microns). This is option chosen by Calistair in developing its materials.

Like zeolites, there are different types of light-activated catalysts. The most effective are activated by lamps emitting radiation having wavelengths less than 365 nm (ultra-violet spectrum). These are generally metal oxides such as zinc, titanium, tungsten or zirconium oxides, etc.

The principle of destruction of contaminants by redox reaction is always the same. Once activated, the catalyst creates electron pairs / holes on its surface. These react with the oxygen and water naturally present in air and also with the pollutants to form free radicals. These free radicals have an extremely short lifetime (a few picoseconds) as they are very reactive with their environment. For this reason, the slightest organic contaminant in contact with the surface of the catalyst is immediately destroyed by a radical reaction, with regeneration of the catalyst. Calistair has opted to use UV-C lamps which, in addition to activating the catalyst, have a germicide effect on most biological contaminants. All the equipment we design is equipped with safety systems to prevent any UV radiation escaping from our machines.

The non-thermal catalyst is probably the most important element of this assembly. Its role is to complete the treatment and ensure that no toxin can be liberated when the micro-organisms are destroyed (e.g. endotoxins).
It also traps and destroys certain toxic chemical contaminants. Its activity particularly targets small aldehyde, acid or alcohol molecules. There are different sorts of non-thermal catalysts depending on the pollutants to be treated and the ambient activation temperatures. The most studied are based on manganese oxide, MnO. Although these catalysts are active at ambient temperature, some thermal input is necessary to activate them. Thus, the lamps used in our equipment also have a role to provide sufficient energy to activate the catalyst.

R&D is part of our DNA.
It drives our development

We are constantly working to develop and optimise the materials, technology and embedded intelligence we use in order to reduce energy consumption still further whilst at the same time improving the intrinsic performance of our solutions, whether this be the flow, microbiological decontamination, chemical decontamination, particulate filtration, compactness or reduced noise level of our mobile air handling units