Nitrogen oxides storage reduction

Examples of multi-disciplinary innovation can also be found in the field of environmental catalysis such as a newly developed catalyst system for exhaust emission control in lean burn automobiles. Japanese workers [17] have successfully merged the disciplines of catalysis, adsorption and process control to develop a so-called NOx-Storage-Reduction (NSR) lean burn emission control system. This NSR catalyst employs barium oxide as an adsorbent which stores NOx as a nitrate under lean burn conditions. The adsorbent is regenerated in a very short fuel rich cycle during which the released NOx is reduced to nitrogen over a conventional three-way catalyst. A process control system ensures for the correct cycle times and minimizes the effect on motor performance. 

Matsumoto, S. (2000) Catalytic Reduction of Nitrogen Oxides in Automotive Exhaust Containing Excess Oxygen by NOx Storage-Reduction Catalyst, Cat. Tech., 4, 102. 

The nitrogen oxide enters the NO reduction reactor where it is contacted with sulfuric acid, a catalyst, and hydrogen. The product is hydroxylamine sulfate. Catalyst is removed from the product, purified, and recycled. The hydroxylamine sulfate solution is then sent to intermediate storage. The chemistry of this step is shown as follows ... 

Matsumoto S, (2000) Catalytic reduction of nitrogen oxides in automotive exhaust containing excess oxygen by NOx storage-reduction catalyst. Cattech 4 102-109... 

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