Catalyzed scr filter and emission treatment system

Abstract

Provided is a catalyst article for simultaneously remediating the nitrogen oxides (NOx), particulate matter, and gaseous hydrocarbons present in diesel engine exhaust streams. The catalyst article has a soot filter coated with a material effective in the Selective Catalytic Reduction (SCR) of NOx by a reductant, e.g., ammonia.

1 . A catalyst article consisting essentially of a wall flow monolith and a catalytic material, wherein the wall flow monolith has a plurality of longitudinally extending passages fatined by longitudinally extending walls bounding and defining said passages, wherein the passages comprise inlet passages having an open inlet end and a closed outlet end, and outlet passages having a closed inlet end and an open outlet end, the wall flow monolith has a porosity of from 50% to 60% and an average pore size of from 10 to 25 microns, and the wall flow monolith contains the catalytic material;
 wherein the catalytic material comprises an SCR catalyst composition including a slurry-loaded washcoat of a zeolite and base metal selected from one or more of a copper and iron component, the washcoat permeating the walls at a loading up to 2.4 g/in 3 , the wall flow monolith having integrated, NOx and particulate removal efficiency in which presence of the catalytic material in the wall flow monolith catalyzes the oxidation of soot.   
     
     
         2 . The catalyst article of  claim 1 , wherein the SCR catalyst composition permeates the walls of the monolith at a concentration of at least 1.3 g/in 3 . 
     
     
         3 . The catalyst article of  claim 2 , wherein there is from 1.6 to 2.4 g/in 3  of SCR catalyst composition disposed on the wall flow monolith. 
     
     
         4 . The catalyst article of  claim 1 , wherein the SCR catalyst composition is effective to catalyze the reduction of NOx at a temperature below about 600° C. and is able to aid in regeneration of the wall flow monolith by lowering the temperature at which soot captured by the wall flow monolith is combusted. 
     
     
         5 . The catalyst article of  claim 1 , wherein the SCR catalyst composition has a thermal resistance to degradation at temperatures greater than 650° C. 
     
     
         6 . The catalyst article of  claim 5 , wherein the SCR catalyst composition is effective to resist degradation upon exposure to sulfur components. 
     
     
         7 . The catalyst article of  claim 1 , wherein the SCR catalyst composition promotes the oxidation of excess NH 3  with 02. 
     
     
         8 . The catalyst article of  claim 1 , wherein the base metal component is a copper component and the zeolite of the SCR catalyst composition has a silica to alumina ratio of at least about 10. 
     
     
         9 . The catalyst article of  claim 8 , wherein the zeolite of the SCR catalyst composition is selected from beta zeolite, USY and ZSM-20. 
     
     
         10 . The catalyst article of  claim 8 , wherein the zeolite of the SCR catalyst composition is a beta zeolite. 
     
     
         11 . The catalyst article of  claim 8 , wherein the zeolite of the SCR catalyst composition has pores with a pore diameter of at least about 7 Angstroms and are connected in three dimensions. 
     
     
         12 . The catalyst article of  claim 1 , wherein the SCR catalyst composition contains one or both of an iron and a copper promoter present in an amount of from about 0.1 to 30 percent by weight of the total weight of promoter plus zeolite. 
     
     
         13 . The catalyst article of  claim 1 , wherein the SCR catalyst composition contains one or both of an iron and a copper promoter present in an amount of from about 1 to 5 percent by weight of the total weight of promoter plus zeolite. 
     
     
         14 . The catalyst article of  claim 1 , wherein the wall flow monolith has a wall porosity of from 55% to 60% with an average pore size of from 10 to 25 microns. 
     
     
         15 . The catalyst article of  claim 1 , wherein the longitudinally extending walls have an inlet side and an opposing outlet side and SCR catalyst is coated on both the inlet and outlet sides of the walls. 
     
     
         16 . A catalyst article consisting essentially of a wall flow monolith and a catalytic material, wherein the wall flow monolith has a plurality of longitudinally extending passages formed by longitudinally extending walls bounding and defining said passages, wherein the passages comprise inlet passages having an open inlet end and a closed outlet end, and outlet passages having a closed inlet end and an open outlet end, the wall flow monolith has a porosity of from
 50% to 60% and an average pore size of from 10 to 25 microns, and the wall flow monolith contains the catalytic material   wherein the catalytic material comprises an SCR catalyst composition including a slurry-loaded washcoat of a zeolite and base metal selected from one or more of a copper and iron component, the washcoat permeating the walls at a loading up to 1.3 g/in 3 , the wall flow monolith having integrated, NOx and particulate removal efficiency in which presence of the catalytic material in the wall flow monolith catalyzes the oxidation of soot.   
     
     
         17 . The catalyst article of  claim 16 , wherein there is from 1.6 to 2.4 g/in 3  of SCR catalyst composition disposed on the wall flow monolith. 
     
     
         18 . The catalyst article of  claim 16 , wherein the SCR catalyst composition contains one or both of an iron and a copper promoter present in an amount of from about 0.1 to 30 percent by weight of the total weight of promoter plus zeolite. 
     
     
         19 . The catalyst article of  claim 16 , wherein the SCR catalyst composition has a thermal resistance to degradation at temperatures greater than 650° C. 
     
     
         20 . The catalyst article of  claim 19 , wherein the SCR catalyst composition in effective to resist degradation upon exposure to sulfur components. 
     
     
         21 - 27 . (canceled)