Catalytic article and the use thereof for the treatment of an exhaust gas

1. A close-coupled catalytic article for the treatment of an exhaust gas, the article comprising an upstream substrate and a downstream substrate,

wherein the upstream substrate is spaced apart from the downstream substrate,

wherein the upstream substrate comprises a first three-way catalyst (TWC) composition and the downstream substrate comprises a second TWC composition, the first and second TWC compositions each comprising an oxygen storage component (OSC),

wherein a loading of the OSC in the downstream substrate is greater than a loading of the OSC in the upstream substrate and is at least 2.2 g/in 3 , and

wherein the upstream substrate is spaced apart from the downstream substrate by from 1 to 5 cm.

2. The close-coupled catalytic article according to claim 1 , wherein the loading of the OSC in the downstream substrate is from 2.2 to 4 g/in 3 .

3. The close-coupled catalytic article according to claim 1 , wherein the loading of the OSC in the upstream substrate is from 0.5 to 2 g/in 3 .

4. The close-coupled catalytic article according to claim 1 , wherein the loading of the OSC in the upstream substrate is at least 0.4 g/in 3 , lower than the loading in the downstream substrate.

5. The close-coupled catalytic article according to claim 1 , wherein a ratio of a volume of the upstream substrate to a volume of the downstream substrate is from 2:1 to 1:2.

6. The close-coupled catalytic article according to claim 1 wherein the total content of OSC in the downstream substrate is greater than the total content of OSC in the upstream substrate.

7. The close-coupled catalytic article according to claim 1 , wherein the first and/or the second TWC compositions each comprise one or more platinum group metals selected from Pd, Pt and Rh on a support.

8. The close-coupled catalytic article according to claim 7 , wherein the support for the platinum group metals is selected from the group consisting of alumina, silica-alumina, alumino-silicates, alumina-zirconia, alumina-ceria and alumina-lanthanum.

9. The close-coupled catalytic article according to claim 1 , wherein the OSC of the first and second TWCs each independently comprise ceria or a cerium-containing mixed oxide.

10. The close-coupled catalytic article according to claim 9 wherein the total cerium content in the downstream substrate is greater than the total cerium content in the upstream substrate.

11. The close-coupled catalytic article according to claim 10 wherein the total cerium content in the downstream substrate is at least 35% greater than the total cerium content in the upstream substrate.

12. The close-coupled catalytic article according to claim 1 , wherein the OSC of the first and second TWCs each independently are selected from the group consisting of cerium oxide, a ceria-zirconia mixed oxide, and an alumina-ceria-zirconia mixed oxide.

13. The close-coupled catalytic article according to claim 1 , wherein first and or second substrates are each a flow-through monolith.

14. The close-coupled catalytic article according to claim 1 , provided in a single can or housing.

15. An exhaust gas treatment system comprising the close-coupled catalytic article according to claim 1 .

16. The exhaust gas treatment system according to claim 15 and further comprising first and second oxygen sensors arranged to monitor oxygen levels across the upstream substrate.

17. A method of treating an exhaust gas from an internal combustion engine comprising the exhaust gas treatment system according to claim 16 and further comprising means to adjust an air-to-fuel ratio within the engine, the method comprising:

monitoring oxygen levels across the upstream substrate and adjusting the air-to-fuel ratio in response to changes in the monitored oxygen levels.

18. A gasoline engine comprising the exhaust gas treatment system according to claim 15 .

19. The close-coupled catalytic article according to claim 1 , wherein the catalytic article is not under the floor.