Composition with oxides of zirconium, cerium and other rare earths with reduced maximum reducible temperature, as well as methods for their production and use in catalysis processes

Abstract

A composition based on zirconium oxides, cerium oxides, and at least one rare earth element other than cerium, having a cerium oxide content of at most 50% by mass, characterized in that, after calcination at 1000 °C for 6 hours, it exhibits a maximum reducibility temperature between 450 °C and 480 °C and a specific surface area between 55 m² 2 / g and 60 m 2 / g.

Description

[0001] The Xth Civil Senate of the Federal Court of Justice has decided to hold an oral hearing on 3 December 2024 found to be right: On appeal by the plaintiff, the judgment of the 3rd Senate (nullity senate) of the Federal Patent Court of 25 October 2022 is amended. European Patent 2 523 907 is hereby partially invalidated with effect for the Federal Republic of Germany to the extent of claims 1 to 10 and 15 and 16 by amending these claims as follows:

Claims

[1] Composition based on zirconium oxides, cerium and at least one rare earth other than cerium, having a cerium oxide content of at most 50% by mass, characterized in that it has, after calcination at 1000°C for 6 hours, a maximum reducibility temperature of between 450°C and 480°C and a specific surface area of between 55 m 2 / g and 60 m 2 / g. [2] fall [3] fall [4] fall [5] Composition according to the preceding claim, characterized in that it has a cerium oxide content of between 10 and 50%. [6] Composition according to one of the preceding claims, characterized in that it has an oxide content of the other rare earth of at most 30%, more particularly of at most 20%. [7] Composition according to one of the preceding claims, characterized in that the rare earth is chosen from the group comprising yttrium, lanthanum, neodymium, praseodymium and gadolinium. [8] Composition according to one of the preceding claims, characterized in that it has, after calcination at 900°C for 6 hours, a specific surface area of at least 60 m 2 / g, more particularly at least 70 m 2 / g. [9] Composition according to one of the preceding claims, characterized in that it can be deagglomerated by ultrasonic treatment and in that it exhibits, after this treatment, a variation in the average diameter (d 50) of the particles which constitute it of at least 30% and more particularly of at least 50%. [10] Composition according to one of the preceding claims, characterized in that it has, after calcination at 1100°C for 4 hours, a maximum reducibility temperature of at most 500°C. [11] Process for preparing a composition according to one of the preceding claims, characterized in that it comprises the following steps: - (a) a liquid mixture is formed comprising compounds of zirconium, cerium and the other rare earth; - (b) said mixture is reacted continuously in a reactor with a basic compound, the residence time in the reactor being at most 100 milliseconds, whereby a precipitate is obtained at the outlet of the reactor; - (c) said precipitate is heated in an aqueous medium, the medium being maintained at a pH of at least 5; - (d) an additive is added to the precipitate obtained in the previous step, chosen from anionic surfactants, non-ionic surfactants, polyethylene glycols, carboxylic acids and their salts and surfactants of the carboxymethylated fatty alcohol ethoxylate type; - (e) the precipitate thus obtained is calcined. [12] Method according to claim 11, characterized in that the compounds of zirconium, cerium and the other rare earth are used as compounds chosen from nitrates, sulfates, acetates, chlorides and ceriammoniacal nitrate. [13] Method according to claim 11 or 12, characterized in that the heating of the precipitate of step (c) is carried out at a temperature of at least 100°C. [14] Method according to one of claims 11 to 13, characterized in that the residence time in the reactor is at most 20 milliseconds. [15] Catalytic system, characterized in that it comprises a composition according to one of claims 1, 5 to 10. [16] Process for treating exhaust gases from internal combustion engines, characterized in that a catalytic system according to claim 15 or a composition according to one of claims 1, 5 to 10 is used as catalyst.