Exhaust gas purification catalyst

1. A catalyst article for treating exhaust gas comprising:

a substrate; and

a catalytic region on the substrate;

wherein the catalytic region comprises a platinum group metal (PGM) component, an oxide, and a rare earth metal component;

wherein the oxide is an inorganic oxide, an oxygen storage component (OSC) material, or a mixture thereof;

wherein the rare earth metal component concentration by element on the surface of the oxide per unit specific surface area of the oxide is 1 μmol/m 2 to 20 μmol/m 2 ; and

wherein the rare earth metal component comprises Nd.

2. The catalyst article of claim 1 , wherein the rare earth metal component concentration by element on the surface of the oxide per unit specific surface area of the oxide is 2 μmol/m 2 to 15 μmol/m 2 .

3. The catalyst article of claim 1 , wherein the PGM component is selected from the group consisting of platinum, palladium, rhodium, and a mixture thereof.

4. The catalyst article of claim 3 , wherein the PGM component is rhodium.

5. The catalyst article of claim 1 , wherein the PGM loading is ranged from 0.1-10 wt. %, based on the total weight of the catalytic region.

6. The catalyst article of claim 1 , wherein the oxide is the OSC material.

7. The catalyst article of claim 6 , wherein the OSC material is selected from the group consisting of cerium oxide, a ceria-zirconia mixed oxide, a ceria-zirconia composite oxide, a composite oxide comprising Ce, Zr, and a rare earth element, and an alumina-ceria-zirconia mixed oxide.

8. The catalyst article of claim 7 , wherein the rare earth element in the composite oxide is La and/or Y.

9. The catalyst article of claim 6 , wherein the PGM dispersion is at least 2% after aging at 1000° C. for 20 hours under redox conditions when the PGM loading is at least 1%, based on the total weight of the catalytic region.

10. The catalyst article of claim 6 , wherein the PGM dispersion is at least 6% after aging at 1000° C. for 20 hours under redox conditions when the PGM loading is less than 1%, based on the total weight of the catalytic region.

11. The catalyst article of claim 1 , wherein the oxide is the inorganic oxide.

12. The catalyst article of claim 11 , wherein the inorganic oxide is selected from the group consisting of alumina, lanthanide-stabilized alumina, alkaline earth stabilized alumina, silica, aluminosilicates, a magnesia/alumina composite oxide, titania, niobia, tantalum oxides, neodymium oxide, yttrium oxide, lanthanides, and mixed oxides or composite oxides thereof.

13. The catalyst article of claim 12 , wherein the inorganic oxide is alumina, a lanthanide-stabilized alumina, or a magnesia/alumina composite oxide.

14. The catalyst article of claim 11 , wherein the PGM dispersion is at least 3% after aging at 1000° C. for 20 hours under redox conditions when the PGM loading is at least 1%, based on the total weight of the catalytic region.

15. The catalyst article of claim 1 , wherein the catalytic region further comprises an alkali or alkali earth material.

16. The catalyst article of claim 15 , wherein the alkali or alkali earth metal is barium or strontium.

17. The catalyst article of claim 1 , wherein the PGM component is supported on the surface layer of the oxide.

18. The catalyst article of claim 1 , wherein the catalyst article further comprises a second catalytic region.

19. An emission treatment system for treating a flow of a combustion exhaust gas comprising the catalyst article of claim 1 .

20. The catalyst article of claim 1 , wherein the rare earth metal component further comprises La.