Development of catalysts based on pyrovanadates for diesel soot combustion

Pyrovanadates of potassium and cesium were prepared and tested as catalysts for low-temperature combustion of carbon. Their catalytic activity was investigated by both temperature-programmed oxidation and thermogravimetric analysis and compared with that displayed by the metavanadates of the same elements, previously proposed as promising catalysts for soot combustion in diesel emissions. Pyrovanadates show an intrinsic catalytic activity noticeably higher than that of the corresponding metavanadates. In particular, cesium pyrovanadate is capable of lowering the ignition temperature of carbon down to 255 degrees C and to provide a high combustion rate already at about 300 degrees C. Such quite interesting results were confirmed in a pilot plant study on the performance of alpha-Al(2)O(3) ceramic foam traps whose pore walls had been lined with catalysts based on either Cs meta- or pyro-vanadates, so as to enable trap self-regeneration by catalytic combustion of the filtered particulate. (C)1999 Elsevier Science B.V. All rights reserved.