Materials Science

En Route to Cleaner Exhaust

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Science  25 Aug 2000:
Vol. 289, Issue 5483, pp. 1257-1259
DOI: 10.1126/science.289.5483.1257e

The emission of nitrogen oxides, or NOx, is the major source of pollution from modern transport vehicles powered by fossil fuels. To reduce emissions, basic oxides are used as adsorbents for NOx, but these adsorbents suffer from deactivation due to the deposition of sulfur oxides, a process called poisoning. If NOx could be eliminated more efficiently from the exhaust, this would in turn make it possible to control better particulate carbon emissions. Sultana et al. have discovered that certain zeolites can trap nitrogen oxides efficiently. The authors flowed representative mixtures of oxidized exhaust gas over a sodium-exchanged Faujasite-type zeolite. The NOx was trapped in the form of dinitrogen trioxide and could be released through changes in pressure; no sulfur poisoning was observed. This system for the temporary storage of NOx may become incorporated into improved emission control devices. - JU

Angew. Chem. Int. Ed.39, 2934 (2000).

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