Laboratory studies of soot oxidation and volatilisation by nitrogen oxides under realistic diesel engine exhaust gas conditions

摘要

Since the particulate soot in the exhaust of diesel engines is still subject to increasing criticism as being a serious threat to air quality and a potential risk to public health the current particulate standard will be tightened in 2005 for heavy duty engines in the EU particulate matter (PM) emission limit of 20/30 mg/kWh in European Stationary and Transient Cycles (ESC/ETC) compared to 100/160 mg/kWh (ESC/ETC) since 2000.Engine manufactures have started timely and intensively to develop new low-emission engines and novel after treatment systems together with catalyst manufactures.One of this new developed after treatment systems is the so called PM-KAT~R (Jacob et al.,2001).This filter free PM catalyst system consist of a platinum oxidation catalyst and metallic substrates with open channels especially designed for temporary storage and oxidation of soot.The significant advantages of the PM-KAT~R compared to standard particulate filters are caused by the open channel structure and characterized by a relative low level back pressure,selective separation of soot (EC) and penetrability for engine lubrication oil incineration ash.Many studies investigate the catalyzed soot NO_2 reaction and some the non catalyzed reaction under laboratory conditions (Neeft et al.,1997;Stanmore et al.,2001) but only little is known about the soot-NO_2 reaction deposited and oxidized under realistic conditions.So the aim of this study is the investigation of the soot NO_2 reaction under exhaust gas conditions of modern diesel engines.