Diesel NOx-Storage Catalyst Systems for Tier 2 BIN5 Legislation

NOx storage catalyst systems (or lean NOx trap, LNT) will most likely play an important role in meeting the future global Diesel emission standards. DaimlerChrysler introduced in 2006 the E 320 BLUETEC Diesel, which represents the first Clean Diesel car with NOx storage catalysts in North America [1]. The vast number of different applications result in a wide spectrum of different operating conditions for the LNT systems. Each of those different environments requires a fine-tuning of the catalyst's properties, particularly sulfur release properties and thermal durability. High average exhaust temperatures typical for a placement close to the engine require high thermal durability. Higher desulfation temperatures are acceptable in such a case since those temperatures are easier to achieve in such a configuration.

In cases where the LNT system is located in an underfloor position exhaust temperatures are generally lower and high desulfation temperatures are difficult to achieve and maintain. Therefore good low temperature activity is required together with fast sulfur release at moderate temperatures. Umicore has added new state of the art LNT systems to its portfolio that are designed to operate under low to medium exhaust temperature conditions. The presented data show how systematic progress has been made in improving sulfur release while maintaining good thermal stability. Umicore is therefore in a position to offer a taylor made LNT solution for most exhaust design scenarios.