| abstract |
A process for the preparation of a composition comprising A1-, Ce- and Zr-oxides, which process comprises the steps of (a) preparing an aqueous solution of a mixture of metal salts of cerium, zirconium and aluminium, wich aqueous solution optionally comprises one or more salts of the Rare Earth Metals other than cerium, (b) adding to the solution obtained a baseat temperatures from 0°C to 95°C and precipitating the mixed metal salts in the form of hydroxides or oxy-hydroxides, (d) treating the aqueous suspension obtained in step (b) with a surfactant, and (e) isolating the precipitate obtained in step (d) and treating said precipitate at a temperature from 450°C to 1200°C, which process is characterized in that the alumina content is in the range from 35 to 80% by weight, and the surface area (BET) of the composition obtained, measured according to DIN (Deutsche Industrie Norm) 66131 after calcining for 2 hours at 1100°C is from 55 to 80 m 2 /g; or is at least 35 m 2 /g after calcining for 20 hours at 1100°C; and a composition comprising A1-, Ce- and Zr-oxides, characterized in that the aluminium content, calculated as aluminium oxide is in the range from 35 to 80% by weight, and the surface area (BET) of the composition measured according to DIN (Deutsche Industrie Norm) 66131 for 2 hours at 1100°C is from 55 to 80 m 2 /g, and/or is at least 35 m 2 /g after calcining for 20 hours at 1100°C obtainable or obtained according such process. |