Catalytic Nano-structured Materials for Next Generation Diesel Particulate Filters

The increasing need for controlled diesel engine emissions and the strict regulations in the abatement of diesel exhaust products lead to an ever increasing use of Diesel Particulate Filters (DPFs) in OEM applications. The periodic regeneration of DPFs (oxidation of soot particles) demands temperatures that rarely appear during engine operation. It is therefore necessary to employ direct or indirect catalytic measures. In the present work, the development and synthesis via aerosol-based routes, of nanostructured base metal oxides for direct soot oxidation, along with their characterization and their evaluation in engine exhaust is described. The synthesized powders were characterized with respect to their phase composition and morphology. XRD, SEM and TEM analysis have shown the nanostructured character of the powders, while Raman spectroscopy was employed for the preliminary characterization of the materials surface chemistry. The catalytic activity of the materials on soot oxidation was evaluated via thermogravimetric analysis (TGA). It was found that they have increased soot oxidation activity at lower temperatures than materials synthesized through a liquid phase route (Liquid Phase Self-propagating High temperature Synthesis, LPSHS). Powders with best catalytic activities were deposited on porous filter structures and were subsequently tested on an engine bench for the evaluation of their catalytic activity under realistic conditions.