Composition useful to treat exhaust gases of internal combustion engines, comprising zirconium oxid

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The composition of the invention consists essentially of oxides of zirconium, cerium, lanthanum or another rare earth element selected from yttrium, gadolinium and samarium with a lanthanum oxide content and the other rare earth oxide of at least 15% and has specific surface areas of at least 40 m / g and at least 15 m / g after calcination for 4 hours at 1000 respectively degrees C and 10 hours at 1150 degrees C after calcination for 10 hours at 1200 degrees C it has a surface of at least 7 M / g, or at least 5 m / g for one embodiment wherein after calcination 10 hours at 1150 degrees C the composition is in the form of a pure solid solution. The composition further has after calcination for 4 hours at 900 degrees C a reducibility rate of at least 80%. The composition may be used as catalyst or catalyst support.