Zone coated catalyst to simultaneously reduce NO

1. An emissions treatment system, comprising:

a) an injector for periodically metering ammonia or an ammonia precursor into an exhaust stream;

b) a first substrate comprising a first SCR catalyst composition, downstream of the injector; wherein the first substrate has an inlet end, an outlet end, a length extending between the inlet end to the outlet end, wall elements and a plurality of passages defined by the wall elements;

wherein the first SCR catalyst composition is disposed on the wall elements from the inlet end toward the outlet end to a length that is less than the substrate's axial length to form an inlet zone;

an NH 3 destruction catalyst composition comprising a platinum group metal component dispersed on a refractory metal oxide, wherein the NH 3 destruction catalyst composition is disposed on the wall elements from the outlet end toward the inlet end to a length that is less than the substrate's axial length to form an outlet zone; and wherein there is from 0.1 to 10 g/ft 3 of platinum group metal component in the outlet zone.

2. The emissions treatment system of claim 1 , wherein the platinum group metal component is selected from the group consisting of platinum, palladium, rhodium and iridium components, and combinations thereof.

3. The emissions treatment system of claim 1 , wherein there is an uncoated zone of at least 0.25 inches between the inlet and outlet zones.

4. The emissions treatment system of claim 1 , wherein the NH 3 destruction catalyst composition further comprises a cerium component.

5. The emissions treatment system of claim 4 , wherein the cerium component is in bulk form.

6. The emissions treatment system of claim 1 , wherein the first SCR catalyst composition comprises V 2 O 5 , WO3 and TiO 2 .

7. The emissions treatment system of claim 1 , wherein the first SCR catalyst composition comprises a zeolite.

8. The emissions treatment system of claim 7 , wherein the zeolite comprises a copper-exchanged or iron-exchanged zeolite.

9. The emissions treatment system of claim 1 , wherein the first substrate is selected from the group consisting of a honeycomb flow-through substrate and a honeycomb wall flow substrate.

10. The emissions treatment system of claim 9 , wherein the first substrate is a honeycomb flow-through substrate.

11. The emissions treatment system of claim 1 , further comprising a diesel engine upstream and in fluid communication with the injector.

12. The emissions treatment system of claim 1 , further comprising a second substrate interposed and in fluid communication with the injector and the first substrate.

13. The emissions treatment system of claim 12 , wherein the second substrate is selected from the group consisting of a honeycomb flow-through substrate, an open-cell foam substrate and a honeycomb wall flow substrate.

14. The emissions treatment system of claim 13 , wherein the second substrate is a honeycomb flow-through substrate comprising a second SCR catalyst composition.

15. The emissions treatment system of claim 14 , wherein the first and second SCR catalyst compositions are the same.

16. The emissions treatment system of claim 1 , wherein there is from 0.1 to less than 5 g/ft 3 of platinum group metal component in the outlet zone.

17. The emissions treatment system of claim 16 , wherein the platinum component is sulfated.

18. A catalyst article comprising a substrate comprising an inlet catalytic zone and an outlet catalytic zone, wherein said substrate has an inlet end, an outlet end, a length extending between the inlet end to the outlet end, wall elements and a plurality of passages defined by the wall elements;

wherein an SCR catalyst composition is disposed on the wall elements from the inlet end toward the outlet end to a length that is less than the substrate's axial length to form the inlet catalytic zone; and

an NH 3 destruction catalyst composition comprising a platinum group metal component dispersed on a refractory metal oxide, which is disposed on the wall elements from the outlet end toward the inlet end to a length that is less than the substrate's axial length to form the outlet catalytic zone; and wherein the outlet catalytic zone comprises from 0.1 to 10 g/ft 3 of platinum group metal component in the outlet catalytic zone.

19. The article of claim 18 , wherein the outlet catalytic zone comprises from 0.5 to 5 g/ft 3 of platinum group metal component.

20. The article of claim 18 , wherein the platinum group metal component is selected from the group consisting of platinum, palladium, rhodium and iridium components, and combinations thereof.

21. The article of claim 18 , comprising an uncoated zone of at least 0.25 inches between the inlet and outlet zones.

22. The article of claim 18 , wherein the NH 3 destruction catalyst composition further comprises a cerium component.

23. The article of claim 22 , wherein the cerium component is in bulk form.

24. The article of claim 18 , wherein the first SCR catalyst composition comprises V 2 O 5 , WO3 and TiO 2 .

25. The article of claim 18 , wherein the first SCR catalyst composition comprises a zeolite.

26. The article of claim 25 , wherein the zeolite comprises a copper-exchanged or iron-exchanged zeolite.

27. The article of claim 18 , wherein the substrate is selected from the group consisting of a honeycomb flow-through substrate and a honeycomb wall flow substrate.

28. The article of claim 27 , wherein the substrate is a honeycomb flow-through substrate.

29. The article of claim 18 , wherein the platinum component is sulfated.