COMPOSITION OF ZIRCONOXIDE AND OXIDES OF CERS, LANTHANS AND OTHER RARE EARTHS, AND A METHOD FOR PRODUCE THEM

Abstract

Zirconium oxide-based composition comprising cerium oxide in an atomic ratio Zr / Ce > 1, and further comprising lanthanum oxide and an oxide of a rare earth other than cerium and lanthanum, characterized in that it has a sulfur content of less than 200 ppm, this content being expressed as weight of sulfate (SO4) relative to the whole composition, in that, after calcination for 6 hours at 1150°C, it has a specific surface area of ​​between 10 m 2 / g and 15 m 2 / g, and in that, after calcination for 6 hours at 1000°C, it has a specific surface area of ​​between 40 m 2 / g and 55 m 2 / g.

Description

[0001] Concerning European Patent 1 527 018 (DE 603 ​​48 280) the 3rd Senate (nullity senate) of the Federal Patent Court has, following the oral hearing on 1 June 2022 found to be right: I. European Patent 1 527 018 is hereby declared partially invalid with effect for the territory of the Federal Republic of Germany to the extent of claims 1 to 10, 16 and 17, provided that these claims are amended as follows:

Claims

[1] Zirconium oxide-based composition comprising cerium oxide in an atomic ratio Zr / Ce > 1, and further comprising lanthanum oxide and an oxide of a rare earth other than cerium and lanthanum, characterized in that it has a sulfur content of less than 200 ppm, this content being expressed as weight of sulfate (SO4) relative to the entire composition, in that after calcination for 6 hours at 1150°C, it has a specific surface area of ​​between 10 m 2 / g and 15 m 2 / g, and that after calcination for 6 hours at 1000°C, it has a specific surface area of ​​between 40 m 2 / g and 55 m 2 / g. [2] Composition according to claim 1, characterized in that after calcination for 6 hours at 1200°C it has a specific surface area of ​​at least 3 m 2 / g. [3] Composition according to one of the preceding claims, characterized in that after calcination for 6 hours at 900°C it has a specific surface area of ​​at least 50 m 2 / g, more particularly at least 70 m 2 / g. [4] Composition according to one of the preceding claims, characterized in that the rare earth is neodymium. [5] Composition according to one of the preceding claims, characterized in that the contents by weight of oxides are at least 50% for zirconium, less than 50% for cerium oxide, at most 5% for lanthanum and at most 15% for the rare earth other than cerium and lanthanum. [6] Composition according to one of the preceding claims, characterized in that it has a cerium oxide content by weight of at most 40%. [7] Composition according to one of the preceding claims, characterized in that it has a content by weight of rare earth oxide other than cerium and lanthanum of between 3% and 10%. [8] Composition according to one of the preceding claims, characterized in that it has a sulfur content of less than 100 ppm. [9] Composition according to one of the preceding claims, characterized in that after calcination at 1000°C for 6 hours it is in the form of a pure solid solution of the oxides of cerium, lanthanum and the other rare earth in zirconium oxide, [10] Composition according to one of the preceding claims, characterized in that after calcination at 1100°C for 6 hours it is in the form of a solid solution of the oxides of cerium, lanthanum and the other rare earth in zirconium oxide. [11] Process for preparing a composition according to one of the preceding claims, characterized in that it comprises the following steps: - a mixture is formed comprising compounds of cerium, lanthanum and the aforementioned rare earth and a sol of a zirconium compound; - the said mixture is brought into contact with a solution of a basic compound, whereby a precipitate is obtained; - said precipitate is heated in an aqueous medium to a temperature of at least 100°C; - the precipitate thus obtained is calcined. [12] Method according to claim 11, characterized in that a sol of a zirconium compound is used which has been obtained by heat treatment of an aqueous solution of a zirconium oxychloride. [13] Method according to claim 11, characterized in that a sol of a zirconium compound is used which has been obtained by attacking a zirconium hydroxide or carbonate with nitric acid in a molar ratio NO3 - / Zr between 1.7 and 2.3 in the case of a hydroxide and 1.7 and 2 in the case of a carbonate. [14] Method according to one of claims 11 to 13, characterized in that the heating of the precipitate is carried out at basic pH. [15] Method according to one of claims 11 to 14, characterized in that the bringing together of the aforementioned mixture with the solution of a basic compound is done by introducing said mixture into this solution. [16] Catalytic system, characterized in that it comprises a composition according to one of claims 1 to 10. [17] Process for treating exhaust gases from internal combustion engines, characterized in that a catalytic system according to claim 16 or a composition according to one of claims 1 to 10 is used as catalyst.