Nitrous oxide emissions from a medium–duty diesel truck exhaust system

Starting in 2010, medium–duty diesel trucks in the USA were introduced with aftertreatment systems that contained precious metal oxidation catalysts, soot filters, and selective catalytic reduction (SCR) systems for control of nitrogen oxides (NO, NO₂). While modern diesel aftertreatment systems have high performance for meeting hydrocarbons, carbon monoxide (CO), NOx, and particulate matter, there is some concern over emission of nitrous oxide (N₂O) that can be formed within the exhaust system. N₂O has an atmospheric lifetime of approximately 114 years and is 298 times more effective than CO₂ at trapping heat in the atmosphere. In this study, the sources of N₂O were compared in the laboratory flow reactor and at the system level on diesel trucks. The interactions of HC with NOx on the DOC and NOx with NH₃ within the SCR catalyst were the predominant mechanisms for N₂O formation. The composite N₂O mass emission was calculated to be approximately 43 mg/mi, resulting in an equivalent CO₂ penalty of about 2%, similar to the 1% to 3% penalty estimated for the global light–duty vehicle fleet.


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  • Accession Number: 01523008
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Mar 27 2014 4:33PM