Patent ID: 8568678
Filing Date: 2013-10-29
Classification: B01D,B01J,F01N,Y02A,Y02T

Abstract:
1. A structured SCR catalyst for an SCR reaction for the reduction of nitrogen oxides in the lean exhaust gas from internal combustion engines using ammonia or a compound which can be decomposed into ammonia as reducing agent, which comprises a plurality of SCR catalytically active material zone layers which are layered on a support body and are contacted in succession by the exhaust gas, wherein the SCR material zone layers are layered on top of one another, wherein the SCR material zone layers are distinguished by different conversion profiles of the SCR reaction and wherein the SCR material zone layer which is contacted first by exhaust gas to be purified is the upper layer, wherein the conversion profile of the upper layer lies at higher temperatures than the conversion profile of the material zone layer which is contacted subsequently by the exhaust gas to be purified, wherein the upper layer comprises iron-exchanged zeolites, and wherein the SCR material zone layer which is subsequently contacted by the exhaust gas to be purified comprises copper-exchanged zeolites.