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N 2 O Formation and Mitigation in Diesel Aftertreatment Systems

Journal Article
2012-01-1085
ISSN: 1946-3936, e-ISSN: 1946-3944
Published April 16, 2012 by SAE International in United States
N
<sub>2</sub>
O Formation and Mitigation in Diesel Aftertreatment Systems
Sector:
Citation: Kamasamudram, K., Henry, C., Currier, N., and Yezerets, A., "N2O Formation and Mitigation in Diesel Aftertreatment Systems," SAE Int. J. Engines 5(2):688-698, 2012, https://doi.org/10.4271/2012-01-1085.
Language: English

Abstract:

The high global warming potential of nitrous oxide (N₂O) led to its recent inclusion in the list of regulated pollutants under the emerging greenhouse gas regulations. While N₂O can be present in small quantities among the combustion products, it can also be generated as a minor byproduct in various types of aftertreatment systems. In this work, a systematic review of sources of N₂O is presented, along with the potential mechanisms of formation in a typical selective-catalytic-reduction-based diesel exhaust aftertreatment system. It is demonstrated that diesel oxidation catalysts (DOC), selective catalytic reduction (SCR) catalyst, and ammonia slip catalyst (ASC) can all potentially contribute to N₂O formation, depending on the catalyst material and exhaust gas conditions, as well as aftertreatment operation strategies. Furthermore, catalysts used in SCR aftertreatment system are also shown to decompose and/or reduce N₂O to N₂ under select conditions. However, the temperature windows of N₂O formation and decomposition/reduction do not overlap. This requires that N₂O control be focused on reducing its formation by means of optimizing catalyst formulation, system architecture, and operation strategies.