Patent ID: 7562522
Filing Date: 2009-07-21
Classification: B01D,F01N,Y02A,Y02T

Abstract:
1. A diesel engine exhaust aftertreatment system, comprising: a lean NOx trap comprising an effective amount of NO an ammonia-SCR catalyst configured to receive gases released from the lean NOx trap and functional to catalyze a reaction with ammonia that can reduce NOx in a lean environment; and an additional catalyst, configured between the lean NOx trap and the ammonia-SCR catalyst, the additional catalyst comprising: wherein the lean NOx trap is functional to generate ammonia under rich exhaust conditions and the ammonia-SCR catalyst is functional to adsorb most of the ammonia so generated; the ammonia-SCR catalyst is functional to reduce NOx passing the lean NOx trap by catalyzing a reaction of NOx with the adsorbed ammonia; and the additional catalyst is functional to mitigate poisoning of the ammonia-SCR catalyst by hydrocarbons.