NH3 CATALYST FOR GASOLINE LEAN BURN ENGINES WITH IMPROVED NH3-FORMATION ACTIVITY

摘要

The present invention relates to a catalyst comprising a substrate and a catalyst coating, wherein the catalyst coating comprises two or more layers, the layers comprising: (a) a first layer provided on the substrate, the layer comprising Pd and Rh; And (b) a second layer provided on the first layer, the second layer comprising Pt and / or Pd; The first and second layers each comprising at least one particulate support material; At least one oxygen storage component (OSC) material; And one or more elements selected from the group of alkali and / or alkaline earth metals, wherein the total amount of alkali and alkaline earth metals contained in the at least one nitric oxide storage material contained in the catalyst is In the range of 0.18 to 2.0 g / in ³ , calculated as the alkali metal oxide M ₂ O and the alkaline earth metal oxide MO, respectively. The invention also relates to a process for the preparation of the catalyst and to a process for the treatment of an exhaust gas stream produced from a gas stream, in particular an internal combustion engine.