Environ. Sci. Technol. 2007, 41, 5789-5794
Secondary Effects of Catalytic Diesel Particulate Filters: Copper-Induced Formation of PCDD/Fs N O R B E R T V . H E E B , * ,† MARKUS ZENNEGG,‡ ERIKA GUJER,‡ PETER HONEGGER,§ KERSTIN ZEYER,§ URS GFELLER,† ADRIAN WICHSER,‡ MARTIN KOHLER,‡ PETER SCHMID,‡ LUKAS EMMENEGGER,§ ANDREA ULRICH,‡ DANIELA WENGER,‡ JEAN-LUC PETERMANN,⊥ JAN CZERWINSKI,⊥ THOMAS MOSIMANN,| MARKUS KASPER,| AND ANDREAS MAYER# Empa, Swiss Federal Laboratories for Materials Testing and Research (EMPA), Laboratory for Solid State Chemistry and Catalysis, Laboratory for Analytical Chemistry, Laboratory for Air Pollution/Environmental Technology U ¨ berlandstrasse 129, CH-8600 Du ¨ bendorf, Switzerland, UASB, Laboratory for Exhaust Emission Control, University of Applied Sciences Biel, Gwerdtstrasse 5, CH-2560 Nidau, Switzerland, Matter Engineering AG, Bremgarterstrasse 62, CH-5610 Wohlen, Switzerland, and Technik Thermischer Maschinen (TTM), Fohrho¨lzlistr. 14b, CH-5443 Niederrohrdorf, Switzerland
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 eightstage 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
