Daiichi Kigenso Kagaku Kogyo Co., Ltd.

Akiko Tatsumi

Sadahiro Yagishita

Hiroyuki Hayashida

Noriyuki Omura

Provided is a cerium-zirconium-based composite oxide having an excellent OSC, high catalytic activity, and excellent heat resistance, and also provided is a method for producing the same. The cerium-zirconium-based composite oxide comprises cerium, zirconium, and a third element other than these elements. The third element is (a) a transition metal element or (b) at least one or more elements selected from the group consisting of rare earth elements and alkaline earth metal elements. After a heat treatment at 1,000&#xb0; C. to 1,100&#xb0; C. for 3 hours, (1) the composite oxide has a crystal structure containing a pyrochlore phase, (2) a value of {I111/(I111+I222)}&#xd7;100 is 1 or more, and (3) the composite oxide has an oxygen storage capacity at 600&#xb0; C. of 0.05 mmol/g or more, and an oxygen storage capacity at 750&#xb0; C. of 0.3 mmol/g or more.

Cerium-zirconium-based composite oxide and method for producing same

The present invention provides a cerium oxide-zirconium oxide based composite oxide that has a large OSC at a low temperature and that has a suitable OSC, and a method for readily producing the composite oxide. Specifically, the present invention provides a cerium oxide-zirconium oxide based composite oxide comprising a mixture of (1) a cerium-zirconium composite oxide from a melting process and (2) cerium dioxide from a wet process, and a method for producing a cerium oxide-zirconium oxide based composite oxide, the method comprising dispersing a cerium-zirconium composite oxide from a melting process in a cerium-containing solution, neutralizing the resulting dispersion; and then performing a heat treatment.

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Osaka, Japan

Akiko Tatsumi