title: Investigation of PCDD/F emissions from mobile source diesel engines: impact of copper zeolite SCR catalysts and exhaust aftertreatment configurations.
abstract: This study investigated the impact of copper zeolite selective catalytic reduction (SCR) catalysts and exhaust aftertreatment configurations on the emissions of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) from mobile source diesel engines. Emissions of PCDD/Fs, reported as the weighted sum of 17 congeners called the toxic equivalency quotient (TEQ), were measured using a modified EPA Method 0023A in the absence and presence of exhaust aftertreatment. Engine-out emissions were measured as a reference, while aftertreatment configurations included various combinations of diesel oxidation catalyst (DOC), diesel particulate filter (DPF), Cu-zeolite SCR, Fe-zeolite SCR, ammonia oxidation catalyst (AMOX), and aqueous urea dosing. In addition, different chlorine concentrations were evaluated. Results showed that all aftertreatment configurations reduced PCDD/F emissions in comparison to the engine-out reference, consistent with reduction mechanisms such as thermal decomposition or combined trapping and hydrogenolysis reported in the literature. Similarly low PCDD/F emissions from the DOC-DPF and the DOC-DPF-SCR configurations indicated that PCDD/F reduction primarily occurred in the DOC-DPF with no noticeable contribution from either the Cu- or Fe-zeolite SCR systems. Furthermore, experiments performed with high chlorine concentration provided no evidence that chlorine content has an impact on the catalytic synthesis of PCDD/Fs for the chlorine levels investigated in this study.
authors: Cummins Inc., 1801 U.S. Highway 51, Stoughton, Wisconsin 53589, United States. jerry.z.liu@cummins.com
authors: Z Gerald
authors: ZG
authors: Liu
authors: John C
authors: JC
authors: Wall
authors: Patrick
authors: P
authors: Barge
authors: Melissa E
authors: ME
authors: Dettmann
authors: Nathan A
authors: NA
authors: Ottinger
mesh_terms: D000393:Air Pollutants / Q000032:analysis* / Q000737:chemistry; D000397:Air Pollution / Q000517:prevention & control / Q000706:statistics & numerical data; D001572:Benzofurans / Q000032:analysis* / Q000737:chemistry; D002384:Catalysis; D003300:Copper / Q000737:chemistry; D000072338:Dibenzofurans, Polychlorinated; D004784:Environmental Monitoring / Q000379:methods*; D010084:Oxidation-Reduction; D000072317:Polychlorinated Dibenzodioxins / Q000031:analogs & derivatives* / Q000032:analysis / Q000737:chemistry; D001335:Vehicle Emissions / Q000032:analysis* / Q000517:prevention & control*; D017641:Zeolites / Q000737:chemistry
chemical_list: D000393:Air Pollutants; D001572:Benzofurans; D000072338:Dibenzofurans, Polychlorinated; D000072317:Polychlorinated Dibenzodioxins; D001335:Vehicle Emissions; D017641:Zeolites; D003300:Copper