Rhodia Operations

Lama Itani

Julien Hernandez

Emmanuel Rohart

Simon Ifrah

Dominique Horbez

Barry William Luke Southward

The present invention relates to a mixed oxide of aluminium, of zirconium, of cerium, of lanthanum and optionally of at least one rare-earth metal other than cerium and lanthanum that makes it possible to prepare a catalyst that retains, after severe ageing, a good thermal stability and a good catalytic activity. The invention also relates to the process for preparing this mixed oxide and also to a process for treating exhaust gases from internal combustion engines using a catalyst prepared from this mixed oxide.

Mixed cerium- and zirconium-based oxide

The composition of the invention is based on oxides of cerium, of zirconium and of at least one rare earth metal other than cerium, with a cerium oxide content of greater than 50% by weight and it has, after calcination at 1000&#xb0; C. for 4 hours, a specific surface area of at least 20 m/g and an amount of mobile oxygen between 200&#xb0; C. and 400&#xb0; C. of at least 0.8 ml O/g. It is prepared by a process in which, in a reactor, a mixture of compounds of cerium, of zirconium and of the other rare earth metal is reacted continuously with a basic compound with a residence time of the reaction medium in the mixing zone of the reactor of at most 100 milliseconds; the precipitate is heated then brought into contact with a surfactant before being calcined.

Composition based on oxides of cerium, of zirconium and of another rare earth metal with high reducibility, preparation process and use in the field of catalysis

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Savigny-sur-Orge, France

Lama Itani