DENOX system

Thus, special converters and advanced engine control techniques are necessary to meet the upcoming stringent NOx emission limits. Two types of catalytic deNOx systems for mobile applications—NSRC using periodic lean/rich operation and the SCR of NOx by NH3 (urea-SCR)—are discussed in Sections VI and VII, respectively. 

SDS (2) [Shell Denox System] An alternative name for DENOX. 

Current prototype DeNOx systems are demonstrating 30-40 % reduction in NOx levels [8]. Research and development are now concentrating on widening the operating temperature "window" at which this conversion can be achieved and improving the thermal durability of the catalyst systems. 

Ammonia-type reductants, which include ammonia, urea, cyanuric acid and different ammonium salts, have been applied so far mainly for stationary sources. The apparent preference for a hydrocarbon reductant for a mobile deNOx system is mainly based on the following reasons (i) Hydrocarbons are always present in a combustion exhaust (ii) Equipping mobile sources witli an ammonia tank is considered unsafe (iii) Ammonia-type reductants require a stringent injection control to prevent ammonia slip (< 5 ppm required [12]) (iv) Ammonia is found to be converted to NO and N2O at liiglier temperatures (> 400 °C) over various SCR catalysts like V2O5 [12 - 14], WO3 [13] and CrjOs [15] (v) SO2 present in a combustion exhaust is often converted to SO3 to produce acidic particulates [13]. 

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. 

Birkhold F et al (2007) Modeling and simulation of the injection of urea-water-solution for automotive SCR DeNOx-systems, Applied Catalysis B Environmental, 70 119-127... 

Koebel M (1999) Comparative Study on the Use of Various Selective Reducing Agents in Automotive DeNOx Systems. 

Felix Birkhold, Ulrich Meingast, Peter Wassermann, and Olaf Deutschmann. Modeling and simulation of the injection of urea-water-solution for automotive scr denox-systems. Applied Catalysis B Environmental, 70(14) 119-127, 2007. Papers presented at the 4th International Conference on Environmental Catalysis (4th ICEC)Heidelberg, Germany, June 05 08, 2005. 

F. Birkhold, U. Meingast, P. Wassermann, and O. Deutschmann. Analysis of the injection of urea-water-solution for automotive scr denox-systems Modeling of two-phase flow and spray/wall-interaction. SAE Technical Papers, 2006. cited By (since 1996)24. 

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