The issue of solid-solid contact in catalytic soot oxidation and the benefits of catalyst nanostructuring to regeneration of catalytic diesel particulate filters

Catalytic (i.e., catalyst-coated) diesel particulate filters (DPFs) represent the best option for removing particulate matter, which is mostly composed of soot, from diesel engine exhaust. In this chapter, the main critical issue for regeneration of catalytic DPFs, i.e., the contact in the solid-solid reaction between soot and catalyst, is addressed ranging from powdered soot-catalyst mixtures to real catalytic filter. The main factors affecting the soot-catalyst contact are discussed in the light of the most important literature results, with a particular emphasis on nanostructured catalysts. The improvement in catalytic properties at the soot-catalyst interface occurring at the nanoscale is analyzed. Challenges to be addressed in the near future are also highlighted.