Chapter 9 Aspects of catalyst development for mobile urea-SCR systems — From Vanadia-Titania catalysts to metal-exchanged zeolites

Abstract Today, urea-SCR is the most efficient process to reduce the nitrogen oxide emissions of diesel vehicles. However, a variety of difficulties had to be overcome in order to adopt the established ammonia-SCR process for the reduction of NO x from stationary power plants, which is characterized by simple steady-state conditions, sufficiently high temperatures and rather low space velocities to diesel vehicles with its highly dynamic operating conditions and space restrictions, requiring a broadening of the operational window of the process as well as improvements of the low-temperature activity, the high-temperature stability and the volumetric activity of the catalysts. The main challenges on this stony way are addressed, stressing the development of suitable catalysts, which are compatible with these demanding operation conditions.

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