Multi-zone catalytic converter

Abstract

Provided is an exhaust article (catalyst) coated on a single substrate, such as a monolithic honeycomb having a plurality of channels along the axial length of the catalyst. Different washcoat compositions are deposited along the length the channel walls of the substrate beginning from either the inlet or outlet axial end of the substrate to form inlet and outlet catalyst layers, respectively. In the coating process, the channel walls are coated with catalyst washcoat compositions to lengths that are less than the substrates' axial length. The architecture of the resulting catalyst layers defines a plurality of zones along the length of the substrate. The properties of each zone of the catalyst can be optimized to address specific catalyst functions by manipulation of both the coating lengths and the catalyst washcoat compositions.

What is claimed:  
     
         1 . An exhaust gas treatment article, comprising: 
 a substrate comprising an inlet axial end, an outlet axial end, wall elements having a length extending between the inlet axial end to the outlet axial end and a plurality of axially enclosed channels defined by the wall elements;    an inlet layer deposited on the wall elements beginning at the inlet axial end and having a length extending for less than the wall elements' length, wherein the inlet layer comprises a first inlet palladium component; and    an outlet layer beginning at the outlet axial end and having a length extending for less than the wall elements' length, the outlet layer at least partially overlying the wall elements and the inlet layer, wherein the outlet layer comprises an outlet palladium component.    
     
     
         2 . The exhaust article of  claim 1 , wherein the inlet layer further comprises: 
 an inlet refractory oxide support, and    an inlet oxygen storage component; and the outlet layer further comprises an outlet refractory oxide support.    
     
     
         3 . An exhaust gas treatment article, comprising: 
 a substrate comprising an inlet axial end, an outlet axial end, wall elements having a length extending between the inlet axial end to the outlet axial end and a plurality of axially enclosed channels defined by the wall elements;    an inlet layer deposited on the wall elements beginning at the inlet axial end and having a length extending for at least 90% and no more than 97% of the wall elements' length, wherein the inlet layer comprises a first inlet palladium component; and    an outlet layer beginning at the outlet axial end and having a length extending for at least 90% and no more than 97% of the wall elements' length, the outlet layer at least partially overlying the wall elements and the inlet layer, wherein the outlet layer comprises an outlet palladium component.    
     
     
         4 . The exhaust article of  claim 3 , wherein the inlet layer further comprises: 
 an inlet refractory oxide support, and    an inlet oxygen storage component; and    the outlet layer further comprises an outlet refractory oxide support.    
     
     
         5 . The exhaust article of  claim 3 , wherein there is at least 5 g/ft 3  of inlet palladium component, and there is at least 5 g/ft 3  of outlet palladium component.  
     
     
         6 . An exhaust gas treatment article, comprising: 
 a substrate comprising an inlet axial end, an outlet axial end, wall elements having a length extending between the inlet axial end to the outlet axial end and a plurality of axially enclosed channels defined by the wall elements;    an outlet layer deposited on the wall elements beginning at the outlet axial end and having a length extending for less than the wall elements' length, wherein the outlet layer comprises a first outlet palladium component; and    an inlet layer beginning at the inlet axial end and having a length extending for less than the wall elements' length, the inlet layer at least partially overlying the wall elements and the inlet layer, wherein the inlet layer comprises an inlet rhodium component.    
     
     
         7 . The exhaust article of  claim 6 , wherein 
 the inlet layer further comprises: an inlet refractory oxide support; and an inlet oxygen storage component; and    the outlet layer comprises an outlet support.    
     
     
         8 . An exhaust gas treatment article, comprising: 
 a substrate comprising an inlet axial end, an outlet axial end, wall elements having a length extending between the inlet axial end to the outlet axial end and a plurality of axially enclosed channels defined by the wall elements;    an outlet layer deposited on the wall elements beginning at the outlet axial end and having a length extending for at least 90% and no more than 97% of the wall elements' length, wherein the outlet layer comprises a first outlet palladium component; and    an inlet layer beginning at the inlet axial end and having a length extending for at least 90% and no more than 97% of the wall elements' length, the inlet layer at least partially overlying the wall elements and the inlet layer, wherein the inlet layer comprises an inlet rhodium component.    
     
     
         9 . The exhaust article of  claim 8 , wherein 
 the inlet layer further comprises: an inlet refractory oxide support; and an inlet oxygen storage component; and    the outlet layer comprises an outlet refractory oxide support.    
     
     
         10 . An exhaust gas treatment article, comprising: 
 a substrate comprising an inlet axial end, an outlet axial end, wall elements having a length extending between the inlet axial end to the outlet axial end and a plurality of axially enclosed channels defined by the wall elements;    a first inlet layer deposited on the wall elements beginning at the inlet axial end and having a length extending for less than the wall elements' length;    a first outlet layer beginning at the outlet axial end and having a length extending for less than the wall elements' length, the first outlet layer at least partially overlying the wall elements and the first inlet layer; and    a second layer that is one of: 
 a) a second inlet layer overlying at least part of the first inlet layer, beginning at the inlet axial end and having a length extending for no more than 50% of the wall elements' length, or  
 b) a second outlet layer overlying at least part of the first outlet layer, beginning at the outlet axial end and having a length extending for no more than 50% of the wall elements' length.  
   
     
     
         11 . The exhaust article of  claim 10 , wherein the first inlet layer and the first outlet extend for at least 60% of the wall elements' length.  
     
     
         12 . The exhaust gas treatment article of  claim 10 , wherein the second layer comprises a washcoat loading of less than 1.5 g/in 3 .  
     
     
         13 . The exhaust gas treatment article of  claim 10 , wherein the second layer comprises a washcoat loading of less than 0.5 g/in 3 .  
     
     
         14 . The exhaust article of  claim 10 , wherein the second layer is according to (a).  
     
     
         15 . The exhaust gas treatment article of  claim 14 , wherein the second inlet layer comprises one or more platinum group metal components having a loading of at least 20 g/ft 3 .  
     
     
         16 . The exhaust article of  claim 14 , wherein the second inlet layer comprises a second inlet palladium component.  
     
     
         17 . The exhaust article of  claim 16 , wherein the second inlet layer further comprises a second inlet platinum component.  
     
     
         18 . The exhaust article of  claim 16 , wherein there is at least 80 g/ft 3  of second inlet palladium component in the second inlet layer.  
     
     
         19 . The exhaust article of  claim 16 , wherein the first inlet layer comprises: 
 a first inlet palladium component,    a first inlet refractory oxide support, and    a first inlet oxygen storage component; and    the first outlet layer comprises:    a first outlet platinum component,    a first outlet rhodium component, and    a first outlet refractory oxide support.    
     
     
         20 . The exhaust article of  claim 19 , wherein the first inlet layer further comprises a first inlet platinum component.  
     
     
         21 . The exhaust article of  claim 10 , wherein the second layer is according to (b).  
     
     
         22 . The exhaust article of  claim 21 , wherein the second outlet layer comprises a second outlet palladium component.  
     
     
         23 . The exhaust article of  claim 22 , wherein the second outlet layer comprises at least 80 g/ft 3  of the second outlet palladium component.  
     
     
         24 . The exhaust article of  claim 22 , wherein the second outlet layer further comprises a second outlet platinum component.  
     
     
         25 . The exhaust article of  claim 22 , wherein the first inlet layer comprises: 
 a first inlet palladium component,    a first inlet refractory oxide support, and    a first inlet oxygen storage component; and    the first outlet layer comprises:    a first outlet platinum component;    a first outlet rhodium component; and    a first outlet refractory oxide support.    
     
     
         26 . The exhaust article of  claim 25 , wherein the first inlet layer composition further comprises a first inlet platinum component.  
     
     
         27 . An exhaust article comprising 
 a substrate comprising an inlet axial end, an outlet axial end, wall elements having a length extending between the inlet axial end to the outlet axial end and a plurality of axially enclosed channels defined by the wall elements;    an undercoat layer deposited on the wall elements and having a length extending from the inlet axial end to the outlet axial end;    a first inlet layer deposited on the undercoat layer beginning at the inlet axial end and having a length extending for less than the wall elements' length;    a first outlet layer beginning at the outlet axial end and having a length extending for less than the wall elements' length, the first outlet layer at least partially overlying the undercoat layer and the first inlet layer; and    a second outlet layer overlying at least part of the first outlet layer, beginning at the outlet axial end and having a length extending for no more than 50% of the wall elements' length.    
     
     
         28 . The exhaust article of  claim 27 , wherein the second outlet layer comprises a second outlet rhodium component.  
     
     
         29 . The exhaust article of  claim 28 , wherein the second outlet layer further comprises a second outlet platinum component.  
     
     
         30 . The exhaust article of  claim 29 , wherein the second outlet layer comprises at least 5 g/ft 3  of a sum of the second outlet component rhodium component and the second outlet platinum component.  
     
     
         31 . The exhaust article of  claim 27 , wherein the undercoat layer comprises hydrocarbon trapping material.  
     
     
         32 . The exhaust article of  claim 27 , wherein the undercoat layer comprises NOx adsorption material.