Catalyst materials

1. A catalyst material comprising a catalyst carrier including porous alumina support particles having a hindrance layer on the alumina support particles, the hindrance layer comprising a sulfate, carbonate, oxide or hydroxide of one or more of barium, strontium, and calcium, the catalyst carrier further including a rare earth oxide, wherein the hindrance layer is effective to prevent the rare earth oxide from forming a complex with the alumina support particles.

2. The catalyst material of claim 1 , wherein the hindrance layer comprises a mixed phase of sulfate, carbonate, oxide and hydroxide.

3. The catalyst material of claim 1 , wherein the hindrance layer comprises a sulfate of one or more of barium, strontium and calcium.

4. The catalyst material of claim 1 , wherein the rare earth oxide forms at least partial layer overlying the hindrance layer.

5. The catalyst material of claim 1 , wherein the rare earth oxide comprises at least one oxide of a rare earth metal selected from Ce, Pr, Nd, Eu, Yb, Sm, and La.

6. The catalyst material of claim 1 , wherein the rare earth oxide comprises at least one oxide of a rare earth metal selected from Ce, Pr, and La.

7. The catalyst material of claim 1 , wherein the rare earth oxide comprises ceria.

8. The catalyst material of claim 1 , wherein the hindrance layer comprises a sulfate of one or more of barium, strontium, zirconium, and calcium.

9. The catalyst material of claim 6 , wherein the rare earth oxide comprises one of cerium oxide and praseodymium oxide that stores and releases oxygen.

10. The catalyst material of claim 5 , wherein the rare earth oxide is complexed with one or more of aluminum, nickel, iron, manganese, and copper, and cobalt, yttrium and zirconia.

11. The catalyst material of claim 5 , wherein the rare earth oxide comprises at least one oxide of neodymium or lanthanum complexed with one or more of nickel, iron, manganese, copper, and aluminum in a perovskite phase.

12. The catalyst material of claim 1 , wherein the alumina support is modify by lanthanum or barium/lanthanum either as an oxide, hydroxide, sulfate, carbonate, and or mixtures thereof.

13. The catalyst material of claim 1 , further comprising a platinum group metal selected from ruthenium, rhodium, palladium, osmium, iridium, or platinum, and mixtures thereof.

14. The catalyst material of claim 13 , wherein the platinum group metal is dispersed in or on the hindrance layer.

15. The catalyst material of claim 13 , wherein the platinum group metal is dispersed on the alumina support.

16. The catalyst material of claim 13 , wherein the platinum group metal is dispersed on the rare earth oxide.

17. The catalyst material of claim 13 , wherein the platinum group metal is dispersed in between the hindrance layer and the rare earth oxide, and wherein the rare earth oxide is on the hindrance layer.

18. The catalyst material of claim 13 , wherein the platinum group metal comprises Pd.

19. The catalyst material of claim 18 , wherein the palladium is dispersed in or on the rare earth oxide.

20. The catalyst material of claim 18 , wherein the palladium is dispersed in or on the hindrance layer.

21. The catalyst material of claim 13 , wherein the platinum group metal comprises Pd and Rh.

22. A catalytic article comprising the catalyst material of claim 13 disposed on a ceramic or metallic honeycomb flow-through substrate.

23. The catalytic article of claim 22 , further comprising an additional oxygen storage component in particulate form.

24. The catalytic article of claim 23 , wherein the additional oxygen storage component comprises ceria.

25. A method of treating a gaseous exhaust stream of a gasoline engine, the exhaust stream including hydrocarbons, carbon monoxide, nitrogen oxide, and other gas components, the method comprising contacting the exhaust stream with the catalytic article of claim 22 .