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Say goodbye to nitrogen oxides!

​Nitrogen oxides, produced mainly when diesel fuel is burned, are harmful pollutants. Liten, a CEA Tech institute, recently modified automotive cabin air filters to effectively filter out nitrogen oxides at ambient temperature, improving air quality for drivers and passengers.

Published on 14 May 2020

​The regulatory limits on nitrogen oxides are frequently exceeded, and half of these harmful pollutants come from motor vehicles. While there are filters—like those on automotive catalytic converters—they are only effective at high temperatures. Researchers at Liten developed a filter that works at ambient temperature and at atmospheric pressure.

They took a conventional mechanical particle filter and covered its surface with an active material designed to trap gaseous pollutants. In this case, the active material added to the fibrous filters (similar to the material used to make FFP2 masks) was a deep eutectic blend. The blend is made up of one substance known for its capacity to trap nitrous oxides and another that improves the first substance's trapping capacity fourfold. Before the enhanced filter can make its way into automotive cabins, it must first be tweaked to further improve its performance and tested to confirm its stability. Ultimately it could filter between 50% and 80% of nitrogen oxides between vehicle inspections, or for around 30,000 km.

A patent on the blend is pending and Liten researchers are now working on expanding the filter's capabilities to NO by transforming it into NO2 before it reaches the filter. The innovation could also be used in building air filtration systems and in domestic air purifiers, for example.

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