ZEOLITE PROMOTED V/TiW CATALYSTS

Abstract

Provided is a catalyst composition for treating exhaust gas comprising a blend of a first component and second component, wherein the first component is an aluminosilicate or ferrosilicate molecular sieve component wherein the molecular sieve is either in H+ form or is ion exchanged with one or more transition metals, and the second component is a vanadium oxide supported on a metal oxide support selected from alumina, titania, zirconia, ceria, silica, and combinations thereof. Also provided are methods, systems, and catalytic articles incorporating or utilizing such catalyst blends.

1 . A catalyst composition for treating exhaust gas comprising a blend of a first component and second component, wherein the first component is an aluminosilicate or ferrosilicate molecular sieve component wherein the molecular sieve is in H+ form, and the second component is a vanadium oxide supported on a metal oxide support selected from alumina, titania, zirconia, ceria, silica, and combinations thereof. 
     
     
         2 . The catalyst of  claim 1 , wherein the molecular sieve has a framework selected from MFI, BEA, and FER. 
     
     
         3 . The catalyst of  claim 2 , wherein the molecular sieve is H+/MFI aluminosilicate. 
     
     
         4 . The catalyst of  claim 1 , wherein the molecular sieve is a BEA ferrosilicate. 
     
     
         5 . The catalyst of  claim 1 , wherein the metal oxide support is titanium oxide. 
     
     
         6 . The catalyst composition of  claim 1 , wherein the second component further comprises tungsten oxide. 
     
     
         7 . The catalyst composition of  claim 1 , wherein the second component further comprises iron vanadate. 
     
     
         8 . The catalyst composition of  claim 1 , wherein the first component and second component are present in the blend in a respective weight ratio of about 5:95 to about 40:60. 
     
     
         9 . The catalyst composition of  claim 1 , wherein the blend comprises about 0.5 to about 5 weight percent the vanadium oxide based on the weight of the first and second components. 
     
     
         10 . A catalytic washcoat comprising a catalyst according to  claim 1 , further comprising one or more fillers, binders, processing aides, water, and dopants. 
     
     
         11 . A catalytic article comprising a substrate coated with or incorporating a catalyst according to  claim 1 , wherein the substrate is selected from a metal flow-through substrate, a ceramic flow-through substrate, a wall-flow filter, a sintered metal filter, a partial filter, and an extruded catalyst honeycomb. 
     
     
         12 . The catalytic article of  claim 11 , further comprising a washcoat having a second catalyst composition for selectively reducing NO x  and/or for oxidizing NH 3 . 
     
     
         13 . The catalytic article of  claim 12 , wherein said second catalyst composition is selected from (a) catalyst blends according to  claim 1 , (b) a transition metal promoted molecular sieve, (c) a platinum group metal catalyst, or (d) a vanadium-based catalyst. 
     
     
         14 . The catalyst article of  claim 11 , wherein the substrate comprises a first layer containing a platinum group metal for oxidizing ammonia and a second layer comprising the catalyst of  claim 1 , wherein the first layer is disposed directly on or within the substrate and the second layer covers the first layer. 
     
     
         15 . A system for treating exhaust gas comprising a selective catalytic reduction (SCR) catalyst upstream of an ammonia slip catalyst (ASC), wherein in at least one of said SCR and ASC catalysts comprise a catalyst according to  claim 1 . 
     
     
         16 . The system of  claim 14 , further comprising a diesel oxidation catalyst having a platinum group metal disposed upstream of said selective catalytic reduction catalyst. 
     
     
         17 . A method for treating an exhaust gas comprising the steps of:
 a. contacting an exhaust gas stream containing NO x  and/or NH 3  in the presence of a catalyst according to  claim 1 ; and   b. converting at least a portion of said NO x  to N 2  and/or converting at least a portion of NH 3  to at least one of N 2  and NO 2 .   
     
     
         18 . The method of  claim 17 , wherein said exhaust gas comprises a ratio of NO to NO 2  from about 4:1 to about 1:3 by volume.