| abstract |
A NOx trap comprises components comprising at least one platinum group metal, at least one NOx storage material and bulk ceria or a bulk cerium-containing mixed oxide deposited uniformly in a first layer on a honeycombed substrate monolith, the uniformly deposited components in the first layer having a first, upstream, zone having increased activity relative to a second, downstream zone for oxidising hydrocarbons and carbon monoxide, and a second, downstream, zone having increased activity to generate heat during a desulphation event, relative to the first, upstream, zone, wherein the second, downstream, zone comprises a dispersion of rare earth oxide, wherein the rare earth oxide loading in the second, downstream zone is greater than the rare earth oxide loading in the first, upstream zone. An exhaust system for a lean burn internal combustion engine, a vehicle comprising a lean burn internal combustion engine and the exhaust system and methods of making the NOx trap according to the invention are also claimed. |