Simultaneous Removal of Soot and NOx Over Silver and Ruthenium-Based Catalysts

Silver- and ruthenium-based materials are herein investigated for the simultaneous removal of particulate matter (soot) and NOx and their behaviour is compared with that of a model Pt–Ba/Al2O3 catalyst. The catalytic activity for diesel soot combustion, in loose contact conditions, is studied by means of TPO (temperature programmed oxidation) while NOx removal is investigated through NOx Storage-Reduction cycles (SRC), performed both in the presence and in the absence of soot. Both the Ag- and Ru-based formulations result active in the soot oxidation, more than the traditional Pt-containing DPNR catalyst. Also, the Ru-based sample shows remarkable performances in the DeNOx-DeSoot activity, although its activity in the reduction step of the stored NOx still needs further improvements.