LTA catalysts having extra-framework iron and/or manganese for treating exhaust gas
Provided are compositions, articles, systems and methods that comprise or use a catalyst composition comprising a zeolite having an LTA structure with iron, manganese or a combination thereof as an extra-framework metal. The zeolite can have a mole ratio of silica-to-alumina (SAR) of about 15 to about 70 and can contain about 0.5 to about 10 weight percent, based on the total weight of the zeolite, of extra-framework iron, manganese or a combination thereof.
1. A catalyst composition comprising an aluminosilicate molecular sieve having an LTA framework and a mole ratio of silica-to-alumina of about 15 to about 70, and about 0.5 to about 10 weight percent of manganese as extra-framework metal, based on the total weight of the molecular sieve material.
2. The catalyst composition of claim 1 , wherein the manganese is present in a loading of about 1 to about 10 weight percent, based on the total weight of the zeolite material.
3. A catalytic article comprising a catalyst composition according to claim 1 and a substrate.
4. The catalytic article of claim 3 , wherein the substrate is a flow-through monolith.
5. The catalyst article of claim 3 , wherein the substrate is a wall-flow filter.
6. The catalyst article of claim 3 , wherein the catalyst composition is within the substrate.
7. The catalyst article of claim 3 , wherein the catalyst composition is on the substrate.
8. The catalyst article of claim 3 , wherein the substrate is extruded and the catalyst composition is within the substrate.
9. The catalyst article of claim 3 , wherein the substrate is extruded and the catalyst composition is a coating on the substrate.
10. A system for treating an exhaust gas comprising:
a. a catalyst article according to claim 3 ; and
b. one or more upstream components selected from a diesel oxidation catalyst, a NO X absorber catalyst, a lean NO X trap, a filter, an NH 3 injector, and an SCR catalyst.
11. A system for treating an exhaust gas of claim 10 , further comprising a downstream ammonia slip catalyst.
12. An engine comprising the catalyst composition of claim 1 .
13. A vehicle comprising the catalyst composition of claim 1 .
14. A method for treating an exhaust gas comprising:
contacting an exhaust gas comprising NO x and a reductant with a catalyst composition according to claim 1 ; and
selectively reducing at least a portion of the NO x to N 2 and H 2 O.
15. The method of claim 13 , wherein the exhaust gas is derived from a lean burn internal combustion engine.
16. The method of claim 14 , wherein the reductant is NH 3 .
17. The method of claim 16 , wherein at least a portion of said NH 3 is derived from a lean NO X trap (LNT), NAC, or a NO X storage catalyst.
18. The method of claim 14 , wherein said exhaust gas contacting the catalyst alternates between rich and lean.