Integrated PM Filter and SCR Catalyst for Lean Burn Engine

Abstract

A wall-flow exhaust gas emissions aftertreatment device for simultaneously reducing the particulate matter and NOx content of the exhaust. The device comprises a number of longitudinal inlet channels and outlet channels, the inlet channels being plugged at the exit face, and the outlet channels being plugged at the entry face. The interiors of the inlet channels are coated with a particulate matter catalyst coating, and the interiors of the outlet channels are coated with a selective catalyst reduction catalyst coating.

1 . A wall-flow exhaust gas emissions aftertreatment device for simultaneously reducing the particulate matter and NOx content of the exhaust, comprising:
 a wall-flow substrate having an entry face and an exit face and a plurality of longitudinal and parallel walls between the entry face and the exit face, the walls defining inlet channels and outlet channels;   the substrate being made from a particulate matter filter material;   the inlet channels being plugged at the exit face, and the outlet channels being plugged at the entry face;   wherein the interiors of the inlet channels are coated with a particulate matter catalyst coating; and   wherein the interiors of the outlet channels are coated with a selective catalyst reduction catalyst coating.   
     
     
         2 . The device of  claim 1 , wherein the substrate is made from one of the following materials: cordierite, silicon carbine, aluminum titanate, or metal fiber. 
     
     
         3 . The device of  claim 1 , wherein the PM catalyst is made from one or more of the following materials: platinum, palladium, rhodium, cerium, zirconium, cobalt, or iron. 
     
     
         4 . The device of  claim 1 , wherein the SCR catalyst is a zeolite-based catalyst. 
     
     
         5 . The device of  claim 1 , wherein the SCR catalyst is made from one of the following materials: Cu-zeolite SCR, Fe-zeolite SCR, or vanadium-based SCR. 
     
     
         6 . The device of  claim 1 , wherein the number of inlet channels and the number of outlet channels are substantially equal. 
     
     
         7 . The device of  claim 1 , wherein the respective ends of the inlet channels and outlet channels are plugged in an alternating pattern, such that the entry and exit faces form a checkerboard pattern. 
     
     
         8 . An exhaust gas aftertreatment method for simultaneously reducing the particulate matter and NOx content of the exhaust gas, comprising:
 directing the exhaust gas to a PM-SCR catalyst having a wall-flow substrate, the substrate having an entry face and an exit face and a plurality of longitudinal and parallel walls between the entry face and the exit face, the walls defining inlet channels and outlet channels;   the substrate being made from a particulate matter filter material;   the inlet channels being plugged at the exit face, and the outlet channels being plugged at the entry face;   wherein the interiors of the inlet channels are coated with a particulate matter catalyst coating;   wherein the interiors of the outlet channels are coated with a selective catalyst reduction catalyst coating; and   
     
     
         8 . An exhaust gas aftertreatment method for simultaneously reducing the particulate matter and NOx content of the exhaust gas, comprising:
 directing the exhaust gas to a PM-SCR catalyst having a wall-flow substrate, the substrate having an entry face and an exit face and a plurality of longitudinal and parallel walls between the entry face and the exit face, the walls defining inlet channels and outlet channels;   the substrate being made from a particulate matter filter material;   the inlet channels being plugged at the exit face, and the outlet channels being plugged at the entry face;   wherein the interiors of the inlet channels are coated with a particulate matter catalyst coating;   wherein the interiors of the outlet channels are coated with a selective catalyst reduction catalyst coating; and   passing the gas into the entry face such that it travels into the inlet channels, through the coated walls of the inlet channels into the outlet channels, and out of the device via the exit face.   
     
     
         9 . The method of  claim 8 , further comprising the step of directing the exhaust gas through an oxidation catalyst before directing the exhaust gas to the PM-SCR catalyst. 
     
     
         10 . The method of  claim 8 , wherein the substrate is made from one of the following materials: cordierite, silicon carbine, aluminum titanate, or metal fiber. 
     
     
         11 . The method of  claim 8 , wherein the PM catalyst is made from one or more of the following materials: platinum, palladium, rhodium, cerium, zirconium, cobalt, or iron. 
     
     
         12 . The method of  claim 8 , wherein the SCR catalyst is a zeolite-based catalyst. 
     
     
         13 . The method of  claim 8 , wherein the SCR catalyst is made from one of the following materials: Cu-zeolite SCR, Fe-zeolite SCR, or vanadium-based SCR. 
     
     
         14 . The method of  claim 8 , wherein the number of inlet channels and the number of outlet channels are substantially equal. 
     
     
         15 . The method of  claim 8 , wherein the respective ends of the inlet channels and outlet channels are plugged in an alternating pattern, such that the entry and exit faces form a checkerboard pattern.