Catalytic composition

1. A catalytic composition for treating a NOx-containing exhaust gas, wherein the composition comprises a copper-substituted small-pore zeolite comprising:

i) Ce and/or La in a total amount of about 5 to about 400 g/ft 3 ; and

ii) Nd and/or Nb in a total amount of about 5 to about 400 g/ft 3 .

2. The catalytic composition of claim 1 , wherein the copper is present in an amount of from about 1 to about 6 wt %.

3. The catalytic composition of claim 1 , wherein the copper is present in an amount of about 3 to about 5.5 wt %.

4. The catalytic composition of claim 1 , wherein the copper is present in an amount of about 4 wt %.

5. The catalytic composition of claim 1 , wherein the small-pore zeolite has a CHA or AEI framework structure type.

6. The catalytic composition of claim 1 , wherein the zeolite has a silica to alumina molar ratio of less than 30.

7. The catalytic composition of claim 1 , wherein the zeolite has a silica to alumina molar ratio of about 5 to about 30.

8. The catalytic composition of claim 1 , wherein the zeolite has a silica to alumina molar ratio of about 10 to about 30.

9. The catalytic composition according to claim 1 , wherein Ce and/or La are present in a total amount of about 50 to about 200 g/ft 3 .

10. The catalytic composition according to claim 1 , wherein Nd and/or Nb are present in a total amount of about 50 to about 200 g/ft 3 .

11. The catalytic of claim 1 , wherein the composition comprises:

Copper in an amount of from about 1 to about 6 wt % of the catalytic composition;

Ce and/or La in a total amount of about 5 to about 400 g/ft 3 ; and

Nd and/or Nb in a total amount of about 5 to about 400 g/ft 3 .

12. A catalyst article for an exhaust gas system, the catalyst article comprising the catalytic composition according to claim 1 and a substrate.

13. An exhaust gas system comprising the catalyst article of claim 12 and a combustion engine.