Secondary effects of catalytic diesel particulate filters: copper-induced formation of PCDD/Fs.
Potential risks of a secondary formation of polychlorinated dibenzodioxins/furans (PCDD/Fs) were assessed for two cordierite-based, wall-through diesel particulate filters (DPFs) for which soot combustion was either catalyzed with an iron- or a copper-based fuel additive. A heavy duty diesel engine was used as test platform, applying the eight-stage ISO 8178/4 C1 cycle. DPF applications neither affected the engine performance, nor did they increase NO, NO2, CO, and CO2 emissions. The latter is a metric for fuel consumption. THC emissions decreased by about 40% when deploying DPFs. PCDD/F emissions, with a focus on tetra- to octachlorinated congeners, were compared under standard and worst case conditions (enhanced chlorine uptake). The iron-catalyzed DPF neither increased PCDD/F emissions, nor did it change the congener pattern, even when traces of chlorine became available. In case of copper, PCDD/F emissions increased by up to 3 orders of magnitude from 22 to 200 to 12 700 pg I-TEQ/L with fuels of < 2, 14, and 110 microg/g chlorine, respectively. Mainly lower chlorinated DD/Fs were formed. Based on these substantial effects on PCDD/F emissions, the copper-catalyzed DPF system was not approved for workplace applications, whereas the iron system fulfilled all the specifications of the Swiss procedures for DPF approval (VERT).
Heeb
Norbert V
NV
Empa, Swiss Federal Laboratories for Materials Testing and Research (EMPA), Laboratory for Solid State Chemistry and Catalysis, Uberlandstrasse 129, CH-8600 Dübendorf, Switzerland. norbert.heeb@empa.ch
Zennegg
Markus
M
Gujer
Erika
E
Honegger
Peter
P
Zeyer
Kerstin
K
Gfeller
Urs
U
Wichser
Adrian
A
Kohler
Martin
M
Schmid
Peter
P
Emmenegger
Lukas
L
Ulrich
Andrea
A
Wenger
Daniela
D
Petermann
Jean-Luc
JL
Czerwinski
Jan
J
Mosimann
Thomas
T
Kasper
Markus
M
Mayer
Andreas
A
D001572:Benzofurans / Q000138:chemical synthesis* / Q000737:chemistry; D002384:Catalysis; D003300:Copper / Q000737:chemistry*; D005374:Filtration; D005740:Gases / Q000032:analysis; D005742:Gasoline; D018986:Motor Vehicles; D052638:Particulate Matter / Q000737:chemistry*; D000072317:Polychlorinated Dibenzodioxins / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000737:chemistry; D001335:Vehicle Emissions / Q000032:analysis
D001572:Benzofurans; D005740:Gases; D005742:Gasoline; D052638:Particulate Matter; D000072317:Polychlorinated Dibenzodioxins; D001335:Vehicle Emissions; D003300:Copper