Layered catalyst composite

1. A layered catalyst composite for controlling vehicular exhaust emissions comprising:

(a) a substrate;

(b) at least one bottom layer having a bottom surface and a top surface wherein the bottom surface is adjacent to, and in contact with, the substrate, said bottom layer comprising a support upon which is deposited: (i) a precious metal component which consists of a platinum metal component and (ii) at least one NO x storage component present in the amount of about 0.3 to about 1.5 g/in 3 ; and

(c) at least one top layer having a bottom surface and a top surface wherein the bottom surface is adjacent to, and in contact with, the top surface of the bottom layer, said top layer comprising a support upon which is deposited (i) at least one precious metal which consists of a component selected from platinum and rhodium metal components, and (ii) at least one NO x storage component present in the amount of 0.0 to less than about 0.3 g/in 3 .

2. The catalyst composite of claim 1 wherein the substrate comprises a ceramic or metal having a honeycomb structure.

3. The catalyst composite of claim 2 wherein the ceramic is selected from the group consisting of cordierite, cordierite-α alumina, silicon nitride, zircon mullite, spodumene, alumina-silica magnesia, zircon silicate, sillimanite, magnesium silicates, zircon, petalite, α-alumina and an aluminosilicate.

4. The catalyst composite of claim 3 wherein the ceramic comprises cordierite.

5. The catalyst composite of claim 2 wherein the metal is selected from the group consisting of titanium and stainless steel.

6. The catalyst composite of claim 1 wherein the support present in the bottom layer comprises a high surface area refractory metal oxide.

7. The catalyst composite of claim 6 wherein the refractory metal oxide is selected from the group consisting of alumina, titania, zirconia; mixtures of alumina with one or more of titania, zirconia and ceria; ceria coated on alumina; and titania coated on alumina.

8. The catalyst composite of claim 7 wherein the metal oxide comprises gamma-alumina.

9. The catalyst composite of claim 7 wherein the metal oxide comprises ceria coated on alumina.

10. The catalyst composite of claim 7 wherein the metal oxide comprises titania coated on alumina.

11. The catalyst composite of claim 1 wherein the support is present in the bottom layer in the amount of about 0.5 to about 3.0 g/in 3 .

12. The catalyst composite of claim 1 wherein the support present in the top layer comprises a high surface area refractory metal oxide.

13. The catalyst composite of claim 10 wherein the refractory metal oxide is selected from the group consisting of alumina, titania, zirconia; mixtures of alumina with one or more of titania, zirconia and ceria; ceria coated on alumina; and titania coated on alumina.

14. The catalyst composite of claim 12 wherein the metal oxide comprises gamma-alumina.

15. The catalyst composite of claim 12 wherein the metal oxide comprises ceria coated on alumina.

16. The catalyst composite of claim 12 wherein the metal oxide comprises titania coated on alumina.

17. The catalyst composite of claim 1 wherein the support is present in the top layer in the amount of about 0.5 to about 3.0 g/in 3 .

18. The catalyst composite of claim 1 wherein the precious metal components present in the top layer consist of the platinum and rhodium metal components.

19. The catalyst composite of claim 1 wherein the precious metal component consists of the platinum metal component.

20. The catalyst composite of claim 1 wherein the precious metal is present in the bottom layer in a loading of about 10 to about 120 g/ft 3 .

21. The catalyst composite of claim 1 wherein the precious metal is present in the top layer in a loading of about 10 to about 120 g/ft 3 .

22. The catalyst composite of claim 1 wherein the bottom layer further comprises: (a) a transition metal component wherein the transition metal is selected from the group consisting of zirconium, cerium, manganese, iron and titanium; or (b) a rare earth metal component wherein the rare earth metal is selected from the group consisting of lanthanum, praseodymium, yttrium and zirconium; or (c) mixtures of one or more transition metal components and one or more rare earth metal components

23. The catalyst composite of claim 22 wherein the transition metal components and/or the rare earth metal components are present in the bottom layer in an amount of about 0.01 to about 0.5 g/in 3 .

24. The catalyst composite of claim 1 wherein the top layer further comprises: (a) a transition metal component wherein the transition metal is selected from the group consisting of zirconium, cerium, manganese, iron and titanium; or (b) a rare earth metal component wherein the rare earth metal is selected from the group consisting of lanthanum, praseodymium, yttrium, zirconium; or (c) mixtures of one or more transition metal components and/or one or more rare earth metal components

25. The catalyst composite of claim 24 wherein the transition metal components and/or the rare earth metal components are present in the top layer in an amount of about 0.01 to about 0.5 g/in 3 .

26. The catalyst composite of claim 1 wherein the NO x storage component in the bottom layer comprises a basic oxygenated compound of an alkali metal or an alkaline earth metal.

27. The catalyst composite of claim 26 wherein the alkali metal is selected from the group consisting of lithium, sodium, potassium and cesium.

28. The catalyst composite of claim 27 wherein the alkali metal comprises potassium.

29. The catalyst composite of claim 28 wherein the alkaline earth metal is selected from the group consisting of magnesium, calcium, strontium and barium.

30. The catalyst composite of claim 29 wherein the alkaline earth metal comprises barium.

31. The catalyst composite of claim 1 wherein the NO x storage component in the top layer comprises a basic oxygenated compound of an alkali metal or an alkaline earth metal.

32. The catalyst composite of claim 31 wherein the alkali metal is selected from the group consisting of lithium, sodium, potassium and cesium.

33. The catalyst composite of claim 32 wherein the alkali metal comprises potassium.

34. The catalyst composite of claim 31 wherein the alkaline earth metal is selected from the group consisting of magnesium, calcium, strontium and barium.

35. The catalyst composite of claim 34 wherein the alkaline earth metal comprises barium.