COMPOSITION BASED ON OXIDES OF ZIRCONIUM, CERIUM, YTTRIUM, LANTHANUM AND OF ANOTHER RARE EARTH,

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Catalytic compositions useful, e.g., for the treatment of internal combustion engine exhaust gases, are based on zirconium oxide in a weight proportion of at least 25%, from 15% to 60% of cerium oxide, from 10% to 25% of yttrium oxide, from 2% to 10% of lanthanum oxide and from 2% to 15% of another rare earth oxide, have a specific surface of at least 15 m2/g and a cubic phase, and are prepared from a mixture of zirconium, cerium, yttrium, lanthanum and the additional rare earth, by precipitating such mixture with a base, heating the precipitate in an aqueous medium, adding thereto a surfactant and calcining the precipitate.