Bimetallic Cu/Mn catalysts for selective catalytic reduction
A catalyst composition for treating an exhaust gas, the catalyst composition comprising a molecular sieve, the molecular sieve comprising exchanged copper and exchanged manganese.
1. A catalyst composition for treating an exhaust gas, the catalyst composition comprising a molecular sieve, the molecular sieve comprising exchanged copper and exchanged manganese, wherein the molecular sieve comprises a small-pore aluminosilicate zeolite.
2. The catalyst composition of claim 1 , wherein the zeolite has a SAR of about 5 to about 200.
3. The catalyst composition of claim 1 , wherein the small-pore zeolite has a crystal framework type selected from AEI, CHA, and combinations thereof.
4. The catalyst composition of claim 1 , wherein the weight ratio of copper to manganese is about 0.1 to about 50.
5. The catalyst composition of claim 1 , wherein the copper and manganese are present in a total amount of about 0.1 to about 10 wt %, based on the weight of the molecular sieve.
6. The catalyst composition of claim 1 , wherein the copper is present in an amount of about 0.05 to about 7 wt %, based on the weight of the molecular sieve.
7. The catalyst composition of claim 1 , wherein the manganese is present in an amount of about 0.05 to about 7 wt %, based on the weight of the molecular sieve.
8. The catalyst composition of claim 1 , wherein the molecular sieve comprises a ratio of copper and manganese to aluminum of <1.
9. The catalyst composition of claim 1 , wherein the catalyst composition is effective to promote a reaction of NH 3 with NOx to form nitrogen and water.
10. A catalyst article, comprising a substrate coated with the catalyst composition of claim 1 .
11. The catalyst article of claim 10 , further comprising one or more additional catalyst compositions.
12. The catalyst article of claim 11 , wherein the one or more additional catalyst compositions comprises a Cu- or Fe-exchanged molecular sieve catalyst.
13. The catalyst article of claim 11 , wherein the molecular sieve comprising exchanged copper and exchanged manganese is present upstream of the one or more additional catalyst compositions.
14. The catalyst article of claim 11 , wherein the molecular sieve comprising exchanged copper and exchanged manganese is present in a top layer and the one or more additional catalyst compositions are present in a bottom layer.
15. The catalyst article of claim 10 , further comprising a catalyst composition comprising a platinum group metal.
16. A method of treating an exhaust gas containing nitrogen oxides, comprising contacting the exhaust gas with a nitrogenous reductant in a presence of the catalyst composition of claim 1 .