Abstract: 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.

Abstract: 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.

Abstract: 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° C. for 4 hours, a specific surface area of at least 20 m2/g and an amount of mobile oxygen between 200° C. and 400° C. of at least 0.8 ml O2/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.

Abstract: 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° C. for 4 hours, a specific surface area of at least 20 m2/g and an amount of mobile oxygen between 200° C. and 400° C. of at least 0.8 ml O2/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 calcine.

Abstract: The invention relates to a composition essentially consisting of a zirconia-ceria mixed oxide, with a zirconia content of at least 40 wt. % and, after 4 hours of calcination at 1000° C., a specific surface area of at least 25 m2/g and a quantity of mobile oxygen between 200° C. and 400° C. of at least 0.5 ml O2/g. Said composition is produced using a method wherein a mixture of cerium and zirconium compounds is continuously reacted with a basic compound in a reactor, with a maximum residence time of the reactive medium in the mixture zone of the reactor of 100 milliseconds; and the precipitate is heated then brought into contact with a surfactant before being calcinated.

Abstract: The invention relates to a composition essentially consisting of ceria-zirconia mixed oxide, with a ceria content of at least 60 wt. % and, after 4 hours of calcination at 1000° C., a specific surface area of at least 15 m2/g and a quantity of mobile oxygen between 200° C. and 400° C. of at least 0.7 ml 02/g. Said composition is produced using a method wherein a mixture of cerium and zirconium compounds is continuously reacted with a basic compound in a reactor, with a maximum residence time of the reactive medium in the mixture zone of the reactor of 100 milliseconds; and the precipitate is heated then brought into contact with a surfactant before being calcinated.