DeNOx trap

The SCR of NOx by NH3 is the best control technology but a new breakthrough would be achieved in power plants by the SCR of NOx using methane as reductant. Regarding deNOx from mobile sources, new concepts are appearing, and NOx trap and plasma-assisted catalytic reduction seem promising. 

Given the failure to generate a robust and reliable HC-SCR system, other solutions were required for gasoline engine deNOx aftertreatment. The eventual system developed involved a relatively novel approach to the removal of NOx from the exhaust emissions of lean-burn gasoline engines. This was to trap NOx from the exhaust on a storage material located in the... 

The proposed deNOx cycle involves NO oxidising on the Fe redox sites to form NO and subsequently being trapped on the BaO (as Ba(N03) ). 

Although the first commercial lean deNOx system was a lean NOx trap (LNT) on the European Toyota Avensis in the early 2000s, and then on the US Dodge Ram truck (Cummins engine) in 2007, the first wide-scale use of deNOx was the implementation of SCR for heavy-duty (HD) tmck applications in Europe in 2005. The US Tier 2 and Cahfornia Low Emission Vehicle (LEVII) regulations were the first to force SCR on light-duty (LD) applications in 2007. SCR did not make its way into NR applications until 2011 in both the US and Europe. 

Currently, the major deNOx after-treatment technologies under consideration include the so-called Lean-NOx Traps (LNT), which are used with direct injection gasoline and Diesel engines, and the Selective Catalytic Reduction (urea-SCR) process. 

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