Modeling catalytic regeneration of diesel particulate filters, taking into account adsorbed hydrocarbon oxidation

Initiation of the regeneration of porous ceramic diesel particulate filters at low exhaust gas temperatures and the subsequent control of the soot oxidation rate is necessary in order to allow a wide applicability of filter systems in diesel-powered vehicles. The use of catalysts in this respect, in particular catalytic fuel additives; has been proven to be successful, leading to a minimization of the system's cost and additional fuel consumption. Better understanding and modeling of the catalytic activity at low temperatures necessitates that one takes into account the oxidation not only of dry particulate but also of the volatile hydrocarbons adsorbed on the particulate. In this paper, the oxidation of the hydrocarbons adsorbed on the particulate is modeled, to allow a better understanding of the filter regeneration behavior at very low temperatures (150-300 degrees C). A simplified reaction scheme and tunable kinetics are employed in the description of adsorbed hydrocarbon oxidation. The mechanism is incorporated in an existing mathematical model, and specific computational case studies are invoked to explain and to model regeneration at low temperatures. The results compare well with experimental evidence and indicate certain directions for further research to better understand this complex process which is essential to the successful application of diesel particulate filters.