Composition based on cerium and zirconium oxides having a specific surface which is stable between 900° c and 1000° c method for the production and use thereof as a catalyst
The inventive composition, according to a first embodiment, consists essentially of a cerium oxide and a zirconium oxide. According to a second embodiment, said composition is based on cerium oxide, zirconium oxide and at least one rare earth oxide other than cerium. After a first 4-hour period of calcination at 900 .C followed by a second 10-hour period of at 1000 .C, the specific surface variation thereof is 20% maximum in the first embodiment and 15% maximum in the second embodiment. The inventive composition can be used as a catalyst, i.e. in the treatment of waste gases from internal combustion engines.
1. A composition consisting essentially of a cerium oxide and a zirconium oxide, wherein after a first calcination at 900° C. for 4 hours followed by a second calcination at 1000° C. for 10 hours, the composition exhibits a change in its specific surface area of at most 5%.
2. The composition as claimed in claim 1 , wherein the composition exhibits a specific surface area of at least 8 m 2 /g after calcination at 900° C. for 4 hours.
3. A composition comprising a cerium oxide, a zirconium oxide and at least one oxide of a rare earth other than cerium, wherein after a first calcination at 900° C. for 4 hours followed by a second calcination at 1000° C. for 10 hours, the composition exhibits a change in its specific surface area of at most 5%.
4. The composition as claimed in claim 3 , wherein the composition exhibits a specific surface area of at least 8 m 2 /g after calcination at 900° C. for 4 hours.
5. A composition consisting essentially of a cerium oxide and a zirconium oxide, wherein after a first calcination at 900° C. for 4 hours followed by a second calcination at 1000° C. for 10 hours, the composition exhibits a change in its specific surface area of at most 20%; and wherein after a first calcination at 900° C. for 4 hours followed by a second calcination at 1100° C. for 10 hours, the composition exhibits a change in its specific surface area of at most 20%.
6. The composition as claimed in claim 5 , wherein the composition exhibits a specific surface area of at least 8 m 2 /g after calcination at 900° C. for 4 hours.
7. The composition as claimed in claim 5 , wherein the composition exhibits a specific surface area of at least 8 m 2 /g after calcination at 1000° C. for 4 hours.
8. The composition as claimed in claim 5 , wherein the composition exhibits a specific surface area of at least 3 m 2 /g after calcination at 1200° C. for 10 hours.
9. The composition as claimed in claim 5 , wherein after a first calcination at 900° C. for 4 hours followed by a second calcination at 1000° C. for 10 hours, the composition exhibits a change in its specific surface area of at most 10%.
10. The composition as claimed in claim 5 , wherein, after a third calcination at 1200° C. the composition exhibits a change in specific surface area between to the specific surface area after calcination at 1000° C. for 10 hours, and the specific surface area after calcination at 1200° C. for 10 hours, of at most 75%.
11. The composition as claimed in claim 5 , wherein, after a third calcination at 1200° C. the composition exhibits a change in specific surface area between the specific surface area after calcination at 1000° C. for 10 hours, and the specific surface area after calcination at 1200° C. for 10 hours, of at most 60%.
12. The composition as claimed in claim 5 , wherein the composition comprises a cerium oxide/zirconium oxide mass ratio of 10/90 to 90/10.
13. A composition comprising a cerium oxide, a zirconium oxide and at least one oxide of a rare earth other than cerium, wherein after a first calcination at 900° C. for 4 hours followed by a second calcination at 1000° C. for 10 hours, the composition exhibits a change in its specific surface area of at most 15%; and wherein, after a first calcination at 900° C. for 4 hours followed by a second calcination at 1100° C. for 10 hours, the composition exhibits a change in its specific surface area of at most 20%.
14. The composition as claimed in claim 13 , wherein the composition exhibits a specific surface area of at least 15 m 2 /g after calcination at 900° C. for 4 hours.
15. The composition as claimed in claim 13 , wherein the composition exhibits a specific surface area of at least 8 m 2 /g after calcination at 1000° C. for 4 hours.
16. The composition as claimed in claim 13 , wherein the composition exhibits a specific surface area of at least 3 m 2 /g after calcination at 1200° C. for 10 hours.
17. The composition as claimed in claim 13 , wherein the composition exhibits a specific surface area of at least 8 m 2 /g after calcination at 1200° C. for 10 hours.
18. The composition as claimed in claim 13 , wherein after a first calcination at 900° C. for 4 hours followed by a second calcination at 1000° C. for 10 hours, the composition exhibits a change in its specific surface area of at most 10%.
19. The composition as claimed in claim 13 , wherein, after a third calcination at 1200° C. the composition exhibits a change in specific surface area between the specific surface area after calcination at 1000° C. for 10 hours, and the specific surface area after calcination at 1200° C. for 10 hours, of at most 75%.
20. The composition as claimed in claim 13 , wherein, after a third calcination at 1200° C. the composition exhibits a change in specific surface area between the specific surface area after calcination at 1000° C. for 10 hours, and the specific surface area after calcination at 1200° C. for 10 hours, of at most 60%.
21. The composition as claimed in claim 13 , wherein the composition comprises a cerium oxide/zirconium oxide mass ratio of 10/90 to 90/10.
22. The composition as claimed in claim 13 , wherein the composition comprises a cerium oxide/zirconium oxide mass ratio of 0.25 to 4.00.
23. In combination, the composition of claim 1 , and (i) a catalytic material deposited thereon, or (ii) a catalytic support.
24. In combination, the composition of claim 3 , and (i) a catalytic material deposited thereon, or (ii) a catalytic support.
25. In combination, the composition of claim 5 , and (i) a catalytic material deposited thereon, or (ii) a catalytic support.
26. In combination, the composition of claim 13 , and (i) a catalytic material deposited thereon, or (ii) a catalytic support.