Mixed oxide based on cerium and zirconium

A mixed oxide comprising zirconium, cerium, lanthanum and optionally at least one rare earth element other than cerium and other than lanthanum (RE) with the following proportion:

• between 8.0% and 45.0% by weight of cerium;
• between 1.0% and 15.0% by weight of lanthanum;
• up to 15.0% by weight of the at least one rare earth element other than cerium and other than lanthanum;
• the total proportion of lanthanum and the at least one rare earth element(s) other than cerium and other than lanthanum being lower than or equal to 25.0%;
• the remainder as zirconium;
• the proportions of the cerium, zirconium, lanthanum, and RE being given by weight of oxide relative to the mixed oxide as a whole,
• the mixed oxide exhibiting the following properties after calcination in air at 1100° C. for 4 hours:
• a specific surface area (S1100° C./4 h) between 25 m2/g and 50 m2/g;
• a pore volume (PV0-300 nm) determined by mercury porosimetry for pores having a diameter below 300 nm between 0.50 cm3/g and 0.90 cm3/g;
• the mixed oxide being in the form of particles with the following properties:
• a d50 between 1.0 μm and 2.5 μm;
• a d90 between 2.0 μm and 9.0 μm
• wherein the above mentioned elements are present in the mixed oxide as oxides.