Method of making mesoporous oxygen storage materials for exhaust gas treatment; said oxygen storage materials and their use

A method for making a mesoporous Oxygen Storage Material (OSM), the method comprising steps of:

• (a) preparing an acidic pre-polymerized solution containing polymerized zirconium oligomers, the the polymerized zirconium oligomers comprising zirconium octamers in an amount ranging from about 30 to 100% by weight based on the polymerized zirconium oligomers;
• (b) adding an acidic solution of cerium and at least one rare earth other than cerium salts to the acidic pre-polymerized solution of zirconium oligomer species to make a polyvalent metal containing mixture;
• (c) adding a complexing agent to the polyvalent metal containing mixture;
• (d) allowing for interaction of the polyvalent metal containing mixture with the complexing reagent comprising anions that have an affinity towards zirconium;
• (e) forming a zirconium-based precursor slurry;
• (f) neutralizing the zirconium-based precursor slurry with a base to achieve co-precipitation of any constituent metal hydroxides;
• (g) washing the co-precipitated metal hydroxides with water to remove cationic and anionic admixtures;
• (h) drying the washed co-precipitated metal hydroxides;
• and
• (i) calcining the washed co-precipitated metal hydroxides to form the mesoporous OSM;
• wherein the mesoporous OSM has a fraction of 2-10 nm pores that is less than 20% by volume.