Patent ID: 6293096
Filing Date: 2001-09-25
Classification: B01D,F01N,Y02A,Y02T

Abstract:
A multiple stage aftertreatment system for reducing the amount of NO.sub.x and carbonaceous particulate matter in engine exhaust gases, comprising:a platinum oxidation catalyst positioned to receive exhaust gas discharged from an internal combustion engine and adapted to oxidize at least a portion the NO.sub.x compounds in said exhaust gas to nitrogen dioxide;a lean NO.sub.x trap adapted to store nitrogen dioxide in said exhaust gas discharged from said NO.sub.x oxidation catalyst and reduce the nitrogen dioxide to nitrogen and water in a gaseous state in the presence of at least a portion of the carbonaceous particulate matter in the engine exhaust gas in cooperation with supplemental hydrocarbon fuel whereby at least portions of said carbonaceous particulate matter and said hydrocarbon fuel are oxidized to carbon dioxide;a carbon trap adapted to oxidize other portions of the carbonaceous particulate matter in said exhaust gas to carbon dioxide; anda hydrocarbon fuel injector disposed downstream the platinum oxidation catalyst and upstream the lean NO.sub.x trap at a position adapted to controllably inject selected amounts of hydrocarbon fuel into a said exhaust gas prior to entry into said lean NO.sub.x trap and thereby provide said supplemental hydrocarbon fuel to said lean NO.sub.x trap.