Zeiolite catalyst containing metal

Abstract

A catalyst composition is provided wherein the composition includes a zeolite having a non-phosphorous CHA crystal structure and having a mean crystalline size of about 1 to about 5 microns; and at least one non-aluminum base metal present in an amount sufficient to achieve a NOx conversion of at least about 65% at a temperature of at least 450° C.

We claim: 
     
         1 . A catalyst composition comprising:
 a. a zeolite having a non-phosphorous CHA crystal structure and having a mean crystalline size of about 1 to about 5 microns; and   b. at least one non-aluminum base metal present in an amount sufficient to achieve a NOx conversion of at least about 65% at a temperature of at least 450° C.   
     
     
         2 . The catalyst composition of  claim 1 , wherein the non-aluminum base metal present in an amount sufficient to achieve a NOx conversion of at least about 75% at a temperature of at least 550° C. 
     
     
         3 . The catalyst composition of  claim 1 , wherein the non-aluminum base metal present in an amount sufficient to achieve a NOx conversion of at least about 85% at a temperature of at least 650° C. 
     
     
         4 . The catalyst composition of  1 , wherein the non-aluminum base metal present in an amount sufficient to achieve a NOx conversion of at least about 70 percent over at temperature range of 250-650° C. 
     
     
         5 . The catalyst composition of  claim 1 , wherein the NOx conversion of at least about 80 percent and a N2 selectivity of at least about 85% over at temperature range of 250-650° C. 
     
     
         6 . The catalyst composition of  claim 1 , wherein non-aluminum base metal is selected from Cr, Ce, Mn, Fe, Co, Ni and Cu. 
     
     
         7 . The catalyst composition of  claim 1 , wherein non-aluminum base metal is Cu. 
     
     
         8 . The catalyst composition of  claim 1 , wherein the non-aluminum base metal is included by ion exchanged. 
     
     
         9 . The catalyst composition of  claim 1 , wherein the non-aluminum base metal is included by incipient wetness. 
     
     
         10 . The catalyst composition of  claim 1 , wherein the non-aluminum base metal is included by isomorphous substitution. 
     
     
         11 . The catalyst composition of  claim 1 , wherein the non-aluminum base metal is included during zeolite synthesis. 
     
     
         12 . The catalyst composition of  claim 1 , wherein the zeolite has a silica-to-alumina ratio of about 10 to about 25. 
     
     
         13 . A catalyst article comprising a substrate coated with a catalyst composition according to  claim 1 . 
     
     
         14 . The catalyst article of  claim 12 , wherein the substrate is a flow-through honeycomb. 
     
     
         15 . The catalyst article of  claim 12 , wherein the substrate is a wall-flow filter. 
     
     
         16 . The catalyst article of  claim 12 , further comprising an ammonia oxidation catalyst. 
     
     
         17 . The catalyst article of  claim 15 , wherein the catalyst of  claim 1  and the ammonia oxidation catalyst are in series and the catalyst of  claim 1  is upstream of the ammonia oxidation catalyst. 
     
     
         18 . A system for treating exhaust gas comprising:
 a. a catalyst composition according to  claim 1 ;   b. an oxidation catalyst comprising at least one platinum group metal.   
     
     
         19 . The system of  claim 18 , wherein the platinum group metal is palladium. 
     
     
         20 . The system of  claim 19 , wherein the palladium is supported on a zeolite.