Catalyzed soot filter

A number of ways was employed to make contact between soot and catalyst. It was shown tliat the contact between soot and catalyst is of prime importance for tlie reactivity of the catalyzed soot oxidation. Several catalysts were found to be unable enhancing the soot oxidation rate when the contact between soot and catalyst is poor. This explains why catalyst coated particulate filters have been found quite inactive under practical conditions. For catalytic systems wliich seem to be able to decrease soot combustion temperatures a possible explanation can be probably found in catalyst mobility. 

Lorch FL Pamio Z G, Gomm S, Gruber M (2004) Audi s DPF solution the advanced catalyzed soot filter. Proceedings of the 3. firternational Exhaust Gas and Particulate Entissions FOTum, Sinsheim, 2004... 

In order to decrease the number of bricks in the posttreatment exhaust line, some combinations can be found such as integrating catalytic treatment and filtration step. The aim of this single brick is to reduce the overall size of the posttreatment system and to reduce the cost of the final engine. One approach to achieve this goal is to coat the soot filter with a catalyst composition effective for the conversion of NO in innocuous components. With this selective catalytic reduction filtration (SCRF) concept, the catalyzed soot filter assumes two functions removal of the particulate and conversion of the NO species to N2 of the exhaust stream (Scheme 35.6). 

Another well-recognized approach for soot abatement is the use of a supported Pt oxidation pre-catalyst (upstream of the filter) aimed at producing NOg (from NO oxidation), which decreases the non-catalyzed oxidation temperature of soot by approximately 200 K (from ca. 773 to 573 K) relative to air oxidation. - - This is one of the basic concepts involved in the so-called NO -aided CRT (continuously regenerated trap), which is proposed as one of the most efficient technologies for soot abatement (Fig. 10.4). - Under... 

Soeger N, Mussmann L, Sesselmann R, Leippe G, Giezelt C, Bailey O, Hori (2005) Impact of Aging and NOx/Soot Ratios on the Performance of a Catalyzed Particulate Filter for Heavy Duty Diesel Applications. SAE Paper 2005-01-0663... 

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