Zeolite catalyst containing metal
View Patent ↗Provided is a catalyst comprising (a) a zeolite material having a mean crystal size of at least about 0.5 μm, having a CHA framework that contains silicon and aluminum, and having a silica-to-alumina mole ratio (SAR) of about 10 to about 25; and (b) an extra-framework promoter metal (M) disposed in said zeolite material as free and/or exchanged metal, wherein the extra-framework promoter metal is copper, iron, and mixtures thereof, and is present in a promoter metal-to-aluminum atomic ratio (M:Al) of about 0.10 to about 0.24 based on the framework aluminum; and optionally comprising (c) at least about 1 weight percent of cerium in said zeolite material, based on the total weight of the zeolite, wherein said cerium is present in a form selected from exchanged cerium ions, monomeric ceria, oligomeric ceria, and combinations thereof, provided that said oligomeric ceria has a particle size of less than 5 μm.
1. A catalyst composition comprising:
a. a zeolite material having a mean crystal size of at least about 0.5 μm, having a CHA framework that contains silicon and aluminum, and having a silica-to-alumina mole ratio (SAR) of about 10 to about 25; and
b. an extra-framework promoter metal (M) disposed in said zeolite material as free and/or exchanged metal,
wherein the extra-framework promoter metal is selected from the group consisting of copper, iron, and mixtures thereof, and is present in a promoter metal-to-aluminum atomic ratio (M:Al) of about 0.10 to about 0.24 based on the framework aluminum.
2. The catalyst composition of claim 1 , wherein said zeolite has an SAR of about 14 to about 18.
3. The catalyst composition of claim 1 , wherein said zeolite is an SSZ-13 isotype.
4. The catalyst composition of claim 3 , wherein said zeolite has a mean crystal size of about 1 μm to about 5 μm.
5. The catalyst composition of claim 1 , wherein said promoter metal is copper.
6. The catalyst composition of claim 5 , wherein a majority of said copper is exchanged copper.
7. The catalyst composition of claim 6 , wherein the catalyst has an M:A ratio of about 0.17 to about 0.24.
8. The catalyst composition of claim 6 , wherein the catalyst has an M:A ratio of about 0.22 to about 0.24.
9. The catalyst composition of claim 6 , wherein the catalyst contains about 2 to about 3 weight percent of said copper.
10. The catalyst composition of claim 4 , wherein the zeolite has an SAR of about 16 to about 18, the promoter metal is copper, a majority of the copper is exchanged copper, and the copper is present in an M:A ratio of about 0.22 to about 0.24.
11. The catalyst composition of claim 1 , further comprising:
c. at least about 1 weight percent of cerium in said zeolite material, based on the total weight of the zeolite, wherein said cerium is present in a form selected from exchanged cerium ions, monomeric ceria, oligomeric ceria, and combinations thereof, provided that said oligomeric ceria has a particle size of less than 5 μm.
12. The catalyst composition of claim 11 , wherein the catalyst composition comprises about 1.35 to about 13.5 weight percent of cerium, based on the total weight of the zeolite.
13. The catalyst composition of claim 12 , wherein said composition is substantially free of Zr, ZrO, Ti, and TiO.
14. A catalytically active washcoat comprising:
a. a metal promoted zeolite material having a CHA framework containing silicon and aluminum and having a silica-to-alumina mole ratio (SAR) of about 10 to about 25; wherein the zeolite is promoted with an extra-framework promoter metal (M) selected from the group consisting of copper, iron, and mixtures thereof, and wherein the extra-framework promoter metal is present in a promoter metal-to-aluminum atomic ratio (M:Al) of about 0.10 to about 0.24 based on the framework aluminum; and
b. one or more stabilizers and/or binders,
wherein the metal promoted zeolite and the one or more stabilizers and/or binders are present together in a slurry.
15. A method for reducing NO x in an exhaust gas comprising:
contacting an exhaust gas derived from a lean-burn combustion process and containing NO x with a catalyst composition comprising:
i. a zeolite material having a CHA framework containing silicon and aluminum and having a silica-to-alumina mole ratio (SAR) of about 10 to about 25; and
ii. an extra-framework promoter metal (M) disposed in said zeolite material as free and/or exchanged metal, wherein the extra-framework promoter metal is selected from the group consisting of copper, iron, and mixtures thereof, and is present in a promoter metal-to-aluminum atomic ratio (M:Al) of about 0.10 to about 0.24 based on the framework aluminum; and
converting at a portion of said NO x to N 2 and H 2 O.
16. The catalytically active washcoat of claim 14 further comprising at least about 1 weight percent of cerium in said zeolite material, based on the total weight of the zeolite, wherein said cerium is present in a form selected from exchanged cerium ions, monomeric ceria, oligomeric ceria, and combinations thereof, provided that said oligomeric ceria has a particle size of less than 5 μm.
17. The catalytically active washcoat of claim 16 comprising the binder, wherein the binder is selected from the group consisting of ceria, alumina, silica, (non zeolite) silica-alumina, naturally occurring clays, TiO 2 , ZrO 2 , and SnO 2 .
18. The method for reducing NO x of claim 15 , wherein the catalyst composition further comprises: iii. at least about 1 weight percent of cerium in said zeolite material, based on the total weight of the zeolite, wherein said cerium is present in a form selected from exchanged cerium ions, monomeric ceria, oligomeric ceria, and combinations thereof, provided that said oligomeric ceria has a particle size of less than 5 μm.