title: Mitigation of PAH and nitro-PAH emissions from nonroad diesel engines.
abstract: More stringent emission requirements for nonroad diesel engines introduced with U.S. Tier 4 Final and Euro Stage IV and V regulations have spurred the development of exhaust aftertreatment technologies. In this study, several aftertreatment configurations consisting of diesel oxidation catalysts (DOC), diesel particulate filters (DPF), Cu zeolite-, and vanadium-based selective catalytic reduction (SCR) catalysts, and ammonia oxidation (AMOX) catalysts are evaluated using both Nonroad Transient (NRTC) and Steady (8-mode NRSC) Cycles in order to understand both component and system-level effects of diesel aftertreatment on emissions of polycyclic aromatic hydrocarbons (PAH) and their nitrated derivatives (nitro-PAH). Emissions are reported for four configurations including engine-out, DOC+CuZ-SCR+AMOX, V-SCR+AMOX, and DOC+DPF+CuZ-SCR+AMOX. Mechanisms responsible for the reduction, and, in some cases, the formation of PAH and nitro-PAH compounds are discussed in detail, and suggestions are provided to minimize the formation of nitro-PAH compounds through aftertreatment design optimizations. Potency equivalency factors (PEFs) developed by the California Environmental Protection Agency are then applied to determine the impact of aftertreatment on PAH-derived exhaust toxicity. Finally, a comprehensive set of exhaust emissions including criteria pollutants, NO2, total hydrocarbons (THC), n-alkanes, branched alkanes, saturated cycloalkanes, aromatics, aldehydes, hopanes and steranes, and metals is provided, and the overall efficacy of the aftertreatment configurations is described. This detailed summary of emissions from a current nonroad diesel engine equipped with advanced aftertreatment can be used to more accurately model the impact of anthropogenic emissions on the atmosphere.
authors: Cummins Inc., 1801 U.S. Highway 51, Stoughton, Wisconsin 53589, United States.
authors: Z Gerald
authors: ZG
authors: Liu
authors: Cummins Inc., 1801 U.S. Highway 51, Stoughton, Wisconsin 53589, United States.
authors: John C
authors: JC
authors: Wall
authors: Cummins Inc., 1801 U.S. Highway 51, Stoughton, Wisconsin 53589, United States.
authors: Nathan A
authors: NA
authors: Ottinger
authors: Cummins Inc., 1801 U.S. Highway 51, Stoughton, Wisconsin 53589, United States.
authors: Dana
authors: D
authors: McGuffin
mesh_terms: D000393:Air Pollutants / Q000032:analysis; D000397:Air Pollution / Q000517:prevention & control*; D001336:Automobiles; D002140:California; D002384:Catalysis; D005742:Gasoline; D015538:Nitrosation; D011084:Polycyclic Aromatic Hydrocarbons / Q000032:analysis*; D014481:United States; D014484:United States Environmental Protection Agency; D001335:Vehicle Emissions / Q000032:analysis* / Q000517:prevention & control*
chemical_list: D000393:Air Pollutants; D005742:Gasoline; D011084:Polycyclic Aromatic Hydrocarbons; D001335:Vehicle Emissions