Transition metal/zeolite scr catalysts

Abstract

A method of converting nitrogen oxides in a gas to nitrogen by contacting the nitrogen oxides with a nitrogenous reducing agent in the presence of a zeolite catalyst containing at least one transition metal, wherein the zeolite is a small pore zeolite containing a maximum ring size of eight tetrahedral atoms, wherein the at least one transition metal is selected from the group consisting of Cr, Mn, Fe, Co, Ce, Ni, Cu, Zn, Ga, Mo, Ru, Rh, Pd, Ag, In, Sn, Re, Ir and Pt.

1 . An exhaust system for treatment of an exhaust gas stream comprising NO x  and particulate matter, the exhaust system comprising:
 an SCR catalyst substrate containing a catalyst comprising a copper-containing, metal-substituted silicoaluminophosphate having a CHA framework structure; and   an ammonia injector or an ammonia precursor injector positioned upstream of the SCR catalyst substrate;   wherein the catalyst is effective to promote the reaction of ammonia with nitrogen oxides to form nitrogen and H 2 O selectively.   
     
     
         2 . The exhaust system of  claim 1 , wherein the metal-substituted silicoaluminophosphate is substituted with one or more of As, B, Be, Co, Fe, Ga, Ge, Li, Mg, Mn, Zn and Zr. 
     
     
         3 . The exhaust system of  claim 2 , wherein the metal-substituted silicoaluminophosphate is substituted with Zr. 
     
     
         4 . The exhaust system of  claim 1 , wherein the metal-substituted silicoaluminophosphate comprises metal-substituted SAPO-34. 
     
     
         5 . The exhaust system of  claim 4 , wherein the metal-substituted SAPO-34 is substituted with one or more of As, B, Be, Co, Fe, Ga, Ge, Li, Mg, Mn, Zn and Zr. 
     
     
         6 . The exhaust system of  claim 5 , wherein the metal-substituted SAPO-34 is substituted with Zr. 
     
     
         7 . The exhaust system of  claim 1 , wherein the catalyst contains a binder selected from the group consisting of alumina, silica, (non-zeolite) silica-alumina, naturally occurring clays, TiO 2 , ZrO 2 , and SnO 2 . 
     
     
         8 . The exhaust system of  claim 7 , wherein the binder comprises ZrO 2 . 
     
     
         9 . The exhaust system of  claim 1 , wherein the catalyst contains between about 0.5 wt. % and about 5 wt. % copper. 
     
     
         10 . The exhaust system of  claim 9 , wherein the catalyst contains between about 3 wt. % copper. 
     
     
         11 . The exhaust system of  claim 1 , wherein the catalyst is combined with a metal-containing zeolite SCR catalyst selected from Beta zeolite, zeolite Y, and ZSM-5. 
     
     
         12 . The exhaust system of  claim 1 , further comprising means for metering urea flowing into the system. 
     
     
         13 . The exhaust system of  claim 1 , further comprising a second substrate interposed between the ammonia injector or ammonia precursor injector and the SCR catalyst substrate. 
     
     
         14 . The exhaust system of  claim 13 , wherein the second substrate is selected from a honeycomb flow through substrate, a wall flow substrate, or a honeycomb wall flow substrate. 
     
     
         15 . The exhaust system of  claim 1 , further comprising an oxidation catalyst upstream of the ammonia injector or ammonia precursor injector. 
     
     
         16 . An exhaust system for treatment of an exhaust gas stream comprising NO x  and particulate matter, the exhaust system comprising:
 an SCR catalyst substrate containing a catalyst comprising a copper-containing silicoaluminophosphate, aluminophosphate, or metal-substituted aluminophosphate having a CHA framework structure; and   an ammonia injector or an ammonia precursor injector positioned upstream of the SCR catalyst substrate;   wherein the catalyst is effective to promote the reaction of ammonia with nitrogen oxides to form nitrogen and H 2 O selectively.   
     
     
         17 . The exhaust system of  claim 16 , wherein the substrate is a filtering substrate. 
     
     
         18 . The exhaust system of  claim 17 , wherein the filtering substrate is a wall-flow filter. 
     
     
         19 . The exhaust system of  claim 16 , wherein the substrate is a flow-through substrate. 
     
     
         20 . The exhaust system of  claim 16 , wherein the substrate comprises a washcoat of the catalyst. 
     
     
         21 . The exhaust system of  claim 16 , wherein the catalyst is combined with a metal-containing small pore zeolite. 
     
     
         22 . The exhaust system of  claim 16 , wherein the catalyst contains a binder selected from the group consisting of alumina, silica, (non-zeolite) silica-alumina, naturally occurring clays, TiO 2 , ZrO 2 , and SnO 2 . 
     
     
         23 . The exhaust system of  claim 22 , wherein the binder comprises ZrO 2 . 
     
     
         24 . The exhaust system of  claim 16 , wherein the catalyst contains between about 0.5 wt. % and about 5 wt. % copper. 
     
     
         25 . The exhaust system of  claim 24 , wherein the catalyst contains between about 3 wt. % copper. 
     
     
         26 . The exhaust system of  claim 16 , wherein the catalyst is combined with a metal-containing zeolite SCR catalyst selected from Beta zeolite, zeolite Y, and ZSM-5. 
     
     
         27 . The exhaust system of  claim 16 , further comprising means for metering urea flowing into the system. 
     
     
         28 . The exhaust system of  claim 16 , further comprising a second substrate interposed between the ammonia injector or ammonia precursor injector and the SCR catalyst substrate. 
     
     
         29 . The exhaust system of  claim 28 , wherein the second substrate is selected from a honeycomb flow through substrate, a wall flow substrate, or a honeycomb wall flow substrate. 
     
     
         30 . The exhaust system of  claim 16 , further comprising an oxidation catalyst upstream of the ammonia injector or ammonia precursor injector. 
     
     
         31 . An exhaust system for treatment of an exhaust gas stream comprising NO x  and particulate matter, the exhaust system comprising:
 an SCR catalyst substrate containing a catalyst comprising copper loaded on at least one of AlPO-34, [Al—As—O]-CHA, [Al—Co—P—O]-CHA, |Co|[Be—P—O]-CHA, |Co 3 (C 6 N 4 H 24 ) 3 (H 2 O) 9 |[Be 18 P 18 O 72 ]-CHA, [Co—Al—P—O]-CHA, [Mg—Al—P—O]-CHA, [Si—O]-CHA, [Zn—Al—P—O]-CHA, [Zn—As—O]-CHA, CoAPO-44, CoAPO-47, DAF-5, GaPO-34, LZ-218, MeAPO-47, MeAPSO-47, (Ni(deta) 2 )-UT-6, SAPO-34, SAPO-47, UiO-21, and ZYT-6;   an ammonia injector or an ammonia precursor injector positioned upstream of the SCR catalyst substrate;   wherein the catalyst is effective to promote the reaction of ammonia with nitrogen oxides to form nitrogen and H 2 O selectively.   
     
     
         32 . The exhaust system of  claim 31 , wherein the substrate is a filtering substrate. 
     
     
         33 . The exhaust system of  claim 32 , wherein the filtering substrate is a wall-flow filter. 
     
     
         34 . The exhaust system of  claim 31 , wherein the substrate is a flow-through substrate. 
     
     
         35 . The exhaust system of  claim 31 , wherein the substrate comprises a washcoat of the catalyst. 
     
     
         36 . The exhaust system of  claim 31 , wherein the catalyst is combined with a metal-containing small pore zeolite. 
     
     
         37 . The exhaust system of  claim 31 , wherein the catalyst contains a binder selected from the group consisting of alumina, silica, (non-zeolite) silica-alumina, naturally occurring clays, TiO 2 , ZrO 2 , and SnO 2 . 
     
     
         38 . The exhaust system of  claim 37 , wherein the binder comprises ZrO 2 . 
     
     
         39 . The exhaust system of  claim 31 , wherein the catalyst contains between about 0.5 wt. % and about 5 wt. % copper. 
     
     
         40 . The exhaust system of  claim 39 , wherein the catalyst contains between about 3 wt. % copper. 
     
     
         41 . The exhaust system of  claim 31 , wherein the catalyst is combined with a metal-containing zeolite SCR catalyst selected from Beta zeolite, zeolite Y, and ZSM-5. 
     
     
         42 . The exhaust system of  claim 31 , further comprising means for metering urea flowing into the system. 
     
     
         43 . The exhaust system of  claim 31 , further comprising a second substrate interposed between the ammonia injector or ammonia precursor injector and the SCR catalyst substrate. 
     
     
         44 . The exhaust system of  claim 43 , wherein the second substrate is selected from a honeycomb flow through substrate, a wall flow substrate, or a honeycomb wall flow substrate. 
     
     
         45 . The exhaust system of  claim 31 , further comprising an oxidation catalyst upstream of the ammonia injector or ammonia precursor injector. 
     
     
         46 . An exhaust system for treatment of an exhaust gas stream comprising NO x  and particulate matter, the exhaust system comprising an SCR catalyst substrate containing a catalyst comprising a Cu-containing silicoaluminophosphate having a CHA framework structure. 
     
     
         47 . The exhaust system of  claim 46 , wherein the Cu-containing silicoaluminophosphate comprises Cu-SAPO-34. 
     
     
         48 . The exhaust system of  claim 47 , wherein the catalyst contains a binder selected from the group consisting of alumina, silica, (non-zeolite) silica-alumina, naturally occurring clays, TiO 2 , ZrO 2 , and SnO 2 . 
     
     
         49 . The exhaust system of  claim 48 , wherein the binder comprises ZrO 2 . 
     
     
         50 . The exhaust system of  claim 46 , wherein the Cu-SAPO-34 contains between about 0.5 wt. % and about 5 wt. % Cu. 
     
     
         51 . The exhaust system of  claim 50 , wherein the Cu-SAPO-34 contains about 3 wt. % Cu. 
     
     
         52 . The exhaust system of  claim 46 , wherein the Cu-containing silicoaluminophosphate having a CHA framework structure is combined with a metal-containing zeolite SCR catalyst selected from Beta zeolite, zeolite Y, and ZSM-5. 
     
     
         53 . The exhaust system of  claim 52 , wherein the Cu-containing silicoaluminophosphate having a CHA framework structure comprises Cu-SAPO-34. 
     
     
         54 . A catalyst article comprising
 a catalyst substrate containing a catalyst comprising a copper-containing, metal-substituted silicoaluminophosphate having a CHA framework structure;   wherein the catalyst is effective to promote the reaction of ammonia with nitrogen oxides to form nitrogen and H 2 O selectively.   
     
     
         55 . A catalyst article comprising
 a catalyst substrate containing a catalyst comprising a copper-containing silicoaluminophosphate, aluminophosphate, or metal-substituted aluminophosphate having a CHA framework structure;   wherein the catalyst is effective to promote the reaction of ammonia with nitrogen oxides to form nitrogen and H 2 O selectively.   
     
     
         56 . A catalyst article comprising
 a catalyst substrate containing a catalyst comprising copper loaded on at least one of AlPO-34, [Al—As—O]-CHA, [Al—Co—P—O]-CHA, |Co|[Be—P—O]-CHA, |Co 3 (C 6 N 4 H 24 ) 3 (H 2 O) 9 |[Be 18 P 18 O 72 ]-CHA, [Co—Al—P—O]-CHA, [Mg—Al—P—O]-CHA, [Si—O]-CHA, [Zn—Al—P—O]-CHA, [Zn—As—O]-CHA, CoAPO-44, CoAPO-47, DAF-5, GaPO-34, LZ-218, MeAPO-47, MeAPSO-47, (Ni(deta) 2 )-UT-6, SAPO-34, SAPO-47, UiO-21, and ZYT-6;   wherein the catalyst is effective to promote the reaction of ammonia with nitrogen oxides to form nitrogen and H 2 O selectively.