Secondary effects of catalytic diesel particulate filters: copper-induced formation of PCDD/Fs

Environ Sci Technol. 2007 Aug 15;41(16):5789-94. doi: 10.1021/es062962x.


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).

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Benzofurans / chemical synthesis*
  • Benzofurans / chemistry
  • Catalysis
  • Copper / chemistry*
  • Filtration
  • Gases / analysis
  • Gasoline*
  • Motor Vehicles
  • Particulate Matter / chemistry*
  • Polychlorinated Dibenzodioxins / analogs & derivatives*
  • Polychlorinated Dibenzodioxins / chemical synthesis
  • Polychlorinated Dibenzodioxins / chemistry
  • Vehicle Emissions / analysis


  • Benzofurans
  • Gases
  • Gasoline
  • Particulate Matter
  • Polychlorinated Dibenzodioxins
  • Vehicle Emissions
  • Copper