Cerium- and zirconium-based mixed oxides
AssigneeRhodia Operations
InventorsSimon Ifrah, Wie Li, Valérie Buissette, Stéphane Denaire, Rui Miguel Jorge Coelho Marques
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Abstract
Disclosed is a composition comprising at least a cerium and zirconium based mixed oxide comprising zirconium, cerium, lanthanum and optionally at least one rare earth other than cerium and lanthanum; said mixed oxide exhibiting a high thermal resistance and are in particular capable of maintaining a large specific surface area even in a high temperature environment. Also disclosed is a process for the synthesis of such compositions.
Claims16
A composition comprising a cerium and zirconium based mixed oxide, wherein the mixed oxide consists of zirconium oxide, cerium oxide, lanthanum oxide and optionally at least one rare earth oxide other than cerium oxide and lanthanum oxide, with the following proportions:
- 5-70% by weight of cerium oxide;
- 20-80% by weight of zirconium oxide;
- 1-15% by weight of lanthanum oxide;
- and
- 0-20% by weight of at least one rare earth other oxide than cerium oxide and lanthanum oxide;
- said mixed oxide exhibiting:
- a specific surface area (SBET) comprised between 40 and 50 m2/g, after calcination at 1100° C. for 4 hours under air;
- a specific surface area (SBET) comprised between 60 and 70 m2/g, after calcination at 1000° C. for 4 hours under air;
- and
- wherein the mixed oxide is constituted of crystallites having an average size between 12 and 18 nm after calcination at 1000° C. for 4 hours under air.
A composition comprising a cerium and zirconium based mixed oxide, wherein the mixed oxide consists of zirconium oxide, cerium oxide, lanthanum oxide, hafnium oxide, and optionally at least one rare earth oxide other than cerium oxide and lanthanum oxide, with the following proportions:
- 5-70% by weight of cerium oxide;
- 20-80% by weight of zirconium oxide;
- 1-15% by weight of lanthanum oxide;
- and
- 0-20% by weight of at least one rare earth other oxide than cerium oxide and lanthanum oxide;
- said mixed oxide exhibiting:
- a specific surface area (SBET) comprised between 40 and 50 m2/g, after calcination at 1100° C. for 4 hours under air;
- a specific surface area (SBET) comprised between 60 and 70 m2/g, after calcination at 1000° C. for 4 hours under air;
- and
- wherein the mixed oxide is constituted of crystallites having an average size between 12 and 18 nm after calcination at 1000° C. for 4 hours under air.
Dependencies are inferred from the claim text.