Metal doped cerium oxide compositions

Patent metadata

Field	Value
Publication number	US-10844258-B2
Application number	US-201515321360-A
Country	US
Kind code	B2
Filing date	Jun 24, 2015
Priority date	Jun 24, 2014
Publication date	Nov 24, 2020
Grant date	Nov 24, 2020

Abstract

The present invention concerns a process for the production of metal doped cerium compositions comprising a cerium oxide and a metal oxide by precipitation. The invention also concerns metal doped cerium compositions providing high crystallites size and exhibiting high thermal stabilities, which may be used as a catalytic support or for polishing applications.

First claim

The invention claimed is:

1. A process for preparing a composition comprising a cerium oxide and at least a metal (M) oxide wherein the metal (M) oxide/cerium oxide molar ratio is comprised between 0.1/100 and 15/100; and said composition exhibits:
a specific surface area, after calcination at 300° C. for 4 hours, comprised between 20 and 100 m 2 /g, and
a decrease ratio of specific surface area, after calcination at 800° C. for 4 hours, comprised between 1 and 60%, the process comprising:
contacting a solution comprising a cerium(III) salt, a cerium(IV) compound and a salt of metal (M) with a base, under an inert atmosphere, whereby a precipitate is obtained; wherein cerium(III) salt/cerium(IV) compound molar ratio is comprised between 75/1 and 500/1;
subjecting the precipitate in solution to a thermal treatment under an inert atmosphere, whereby the composition is obtained, wherein metal (M) oxide/cerium(IV) oxide molar ratio of said composition is comprised between 0.1/100 and 15/100; and at least one of the contacting step or the subjecting step is carried out in the presence of nitrate ions.

2. The process according to claim 1 , wherein said process further comprises acidifying and washing the product obtained in a preceding step.

3. The process according to claim 2 , wherein the pH of the medium after acidification is comprised between 2 and 5.

4. The process according to claim 1 , wherein said process further comprises calcining the composition.

5. The process according to claim 1 , wherein metal (M) is selected from the group consisting of: Zr, Al, La, Pr, Nd, Y and Sr.

6. The process according to claim 1 , wherein the metal (M) oxide/cerium oxide molar ratio is comprised between 1/100 and 7/100.

7. The process according to claim 1 , wherein the composition exhibits:
a specific surface area, after calcination at 300° C. for 4 hours, comprised between 20 and 80 m 2 /g, and
a decrease ratio of specific surface area, after calcination at 800° C. for 4 hours, comprised between 1 and 35%.

8. A composition comprising a cerium oxide and a metal (M) oxide, wherein the metal (M) oxide/cerium oxide molar ratio is comprised between 0.1/100 and 15/100; and
said composition exhibits:
a specific surface area, after calcination at 300° C. for 4 hours, comprised between 20 and 100 m 2 /g, and
a decrease ratio of specific surface area, after calcination at 800° C. for 4 hours, comprised between 1 and 60%, and

wherein the composition comprises secondary particles made of primary particles comprising a cerium oxide and a metal (M) oxide, said primary particles having an average size D50 comprised between 10 and 60 nm with a standard deviation of at most 30% of the value of said average size.

9. The composition according to claim 8 , wherein the average size D50 of the primary particles is comprised between 15 and 40 nm.

10. The composition according to claim 8 , wherein the metal (M) is selected from the group consisting of: rare earth elements and alkaline earth metal elements, said metal (M) having a higher ionic radius value than cerium.

11. The composition according to claim 10 , wherein said composition exhibits:
a specific surface area, after calcination at 300° C. for 4 hours, comprised between 20 and 80 m 2 /g, and
a decrease ratio of specific surface area, after calcination at 800° C. for 4 hours, comprised between 1 and 35%.

12. The composition according to claim 8 , wherein the metal (M) is selected from the group consisting of: transition metal elements and post transition metal elements, said metal (M) having a lower ionic radius value than cerium.

13. The composition according to claim 12 , wherein said composition exhibits:
a specific surface area, after calcination at 300° C. for 4 hours, comprised between 60 and 100 m 2 /g, and
a decrease ratio of specific surface area, after calcination at 800° C. for 4 hours, comprised between 1 and 60%.

14. A suspension comprising the composition as defined in claim 8 , and a liquid phase.

15. A method of removing a portion of a substrate, the method comprising:
contacting at least a suspension according to claim 14 and the substrate to be polished, and
performing the polishing on the substrate.

16. A method of removing a portion of a substrate, the method comprising:
providing at least a suspension according to claim 14 ,
contacting at least the suspension and the substrate to be polished, and
performing the polishing on the substrate.

17. A catalytic system comprising at least a composition according to claim 8 .

18. A process for the treatment of exhaust gases from internal combustion engines, the process comprising contacting the exhaust gases with a catalytic system according to claim 17 .

19. A process for the purification of air, the process comprising contacting the air with the catalytic system according to claim 17 .

20. The composition according to claim 8 , wherein the metal (M) oxide/cerium oxide molar ratio is comprised between 1/100 and 7/100.

21. The composition according to claim 8 , wherein said primary particles have an average size D50 with a standard deviation of at most 15% of the value of said average size.

22. The composition according to claim 8 , wherein said primary particles have an average size D50 with a standard deviation of at most 10% of the value of said average size.

Assignees

• Rhodia Operations

Inventors

• Ohtake Naotaka
• Yuasa Manabu
• Sasaki Toshihiro
• Suda Eisaku
• DALENCON Lauriane

Classifications

• B01J35/77

  Compounds characterised by their crystallite size · CPC title

• B01J2235/30

  Scanning electron microscopy; Transmission electron microscopy · CPC title

• B01J35/45

  Nanoparticles · CPC title

• B01J2235/15

  X-ray diffraction · CPC title

• B01J35/70

  characterised by their crystalline properties, e.g. semi-crystalline (catalysts comprising carbon B01J21/18; molecular sieves B01J29/00) · CPC title