Secondary Effects of Catalytic Diesel Particulate Filters:  Copper-Induced Formation of PCDD/Fs

Abstract

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).

An Overview of PCDD/F Inventories and Emission Factors from Stationary and Mobile Sources: What We Know and What is Missing

“…Many factors, such as fuels, engine types, test modes, after treatment technologies that can affect PCDD/F emissions from vehicles have been discussed in previous study and review articles (Heeb et al, 2007;Chuang et al, 2010Chuang et al, , 2011Chang et al, 2014b;Rey et al, 2014;Mwangi et al, 2015). Here we aim to focus on how to conduct vehicular exhaust samplings to obtain better quality data to estimate PCDD/F emission factors from mobile sources.…”

The Influences of Diesel Particulate Filter Installation on Air Pollutant Emissions for Used Vehicles

“…Heeb et al (2007) assessed 2 kinds of DPFs installed on a heavy-duty diesel engine. Their results show THC emissions decreased by about 40% when deploying DPFs.…”

Levels, profiles and gas–particle distribution of atmospheric PCDD/Fs in vehicle parking lots of a South China metropolitan area

“…Formation of PCDD/Fs in vehicle engines requires both incomplete combustion process and presence of chlorine (UNEP, 2003), which may arise from Cl À in airborne particulates (Deng et al, 2011). Furthermore Cu, a catalyst for PCDD/F formation (Heeb et al, 2007), was also found in residue formed in the fuel supply system of LPG-vehicles for the usage of copper pipeline (Gao et al, 2007). Our data suggested that PCDD/ Fs emitted from LPG-buses might be lower than HDDVs, but higher than gasoline-powered cars.…”

“…Summarizing published data, PCDD/F emission factors are typically in the range of 0.36-9500 pg I-TEQ km À1 (7.0-27440 pg I-TEQ L À1 ) ) and are correlated with engine type, load and age, fuel type and quality, driving mode, etc. Ryan, 1997, 2002;Miyabara et al, 1999;Kim et al, 2003;Heeb et al, 2007). Low load rates and idle conditions reportedly greatly increase dioxin emission from diesel-vehicles (Kim et al, 2003;Chang et al, 2004).…”