Architectural diesel oxidation catalyst for enhanced NO2 generator

A device for the purification of diesel exhaust gases, which device comprises a zoned arrangement of catalysts, in the flow direction of the exhaust gas,

• (a) as a leading catalyst a first oxidation catalyst disposed on a first carrier substrate and immediately following as a trailing catalyst, a second oxidation catalyst disposed on a second carrier substrate,
• wherein the first and second oxidation catalysts contain palladium and platinum in their catalytically active coatings, wherein said first and second carrier substrates are through flow substrates, or
• (b) as a leading catalyst a first oxidation catalyst disposed on a carrier substrate and immediately following as a trailing catalyst, a second oxidation catalyst disposed on said carrier substrate, wherein said carrier substrate is a through flow substrate,
• wherein the first and second oxidation catalysts contain palladium and platinum in their catalytically active coatings;
• and further wherein the total quantity of platinum and palladium in the leading catalyst is high relative to the trailing catalyst,
• and further wherein the ratio of platinum to palladium in the leading catalyst is relatively low, and the ratio of platinum to palladium in the trailing catalyst is relatively high,
• and further wherein the loading of Pt:Pd in the leading oxidation catalyst is from 30 to 250 g/ft3 and the loading of Pt:Pd in the trailing catalyst is from 5 to 100 g/ft3.