Katalysator til nitrogenoxid-formindskelse i udstødsgassen fra en forbrændingsmotor

In the denitrification of exhaust gas from internal combustion engines, in particular from diesel engines, there is always the problem, if the process of selective catalytic reduction is used, that it is desired to set high degrees of separation for the nitrogen oxides and only a very low ammonia slip on the catalyst for all load states of the internal combustion engine. For this purpose, the invention provides a catalyst (8) which comprises a catalyst support (26,28) and a catalytically active layer (34) and in which the storable quantity of reducing agent, in most cases ammonia, increases per unit length in the direction of flow of the exhaust gas (30). The result of this is that the catalyst (8), with respect to its response behaviour and its capacity for storing ammonia, rapidly follows, alternating operating states of the internal combustion engine along its flow path without significant slip of ammonia and nitrogen oxides. The invention can be used in principle in all internal combustion engines which run with excess air.