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Combined Soot Combustion and NOx Removal

The widespread use of Diesel engine and the severe emission limits imposed by law led in recent years to focus the attention on new technologies able to reduce the main pollutants emission from these engines, i.e. particulate matter (soot) and NOx. A new promising integrated after-treatment system known as DPNR (Diesel Particulate NOx Reduction) has been recently developed by the Toyota group. This system consists of both a new catalytic filter and a new diesel combustion technology; as a result, it can reduce both particulate and NOx. The particulate filter is coated with a LNT catalytic material (e.g. Pt-Ba/Al2O3); such catalyst works under cycling conditions: NOx are trapped under lean conditions - with simultaneous soot oxidation - while reduction of the stored NOx to N2 is accomplished during a short period under rich conditions. Many aspects of the catalytic performances, of the reaction mechanism and of the role of the different components have not been completely clarified yet. The final target of the activity research is to understand the mechanism of DPNR catalytic system (i.e. identification of active species in the reaction and the rationalization of their role in the used catalytic materials). Indeed, the detailed knowledge of the catalytic materials, the better comprehension of the key parameters that govern the catalytic processes could represent a real opportunity to develop new catalytic systems to reduce NOx and soot emissions.

Faculties involved in the project are: Lidia Castoldi, Pio Forzatti, Luca Lietti, Roberto Matarrese.