| abstract |
The invention relates to a catalytically active material for reacting nitrogen oxides with ammonia in the presence of hydrocarbons. The material consists of an inner core ( 1 ) made of a zeolite exchanged with one or more transition metals or a zeolite-like compound exchanged with one or more transition metals. The core of the catalytically active material is encased by a shell ( 2 ), which is made of one or more oxides selected from silicon dioxide, germanium dioxide, aluminum oxide, titanium oxide, tin oxide, cerium oxide, zirconium dioxide, and mixed oxides thereof. |