| 简介 |
Composition containing zirconium oxide (>=25 wt.%), cerium oxide (15-60 wt.%) and yttrium oxide (10-25 wt.%), comprises lanthanum oxide (2-10 wt.%) and an additional rare earth oxide (2-15 wt.%) other than the oxides of cerium, lanthanum and yttrium. The composition presents a specific surface of >=15 m2>/g, after calcination for 10 hours at 1150[deg]C and a cubic phase. Independent claims are included for : (1) the preparation of the composition comprising forming a mixture containing zirconium, cerium, yttrium, lanthanum and additional rare earth compounds, putting the mixture in the presence of a basic compound to obtain a precipitate, heating the precipitate in an aqueous medium, adding an additive such as anionic- or nonionic- surfactants, polyethylene glycols, carboxylic acids and their salts or carboxymethyl fatty alcohol ethoxylates surfactants to the obtained precipitate and calcining the obtained precipitate; (2) a catalytic system, comprising the composition; and (3) treatment of exhaust fumes of internal combustion engines, comprising using the catalytic system or the composition, as catalyst. |
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