Nippon Denko Co., Ltd

Johnson Matthey Public Limited Company

Tomoharu Itoh

Takeshi Watanabe

Yusuke Hidaka

Shuhei Nagaoka

Takashi Yamada

Masasuke Yamaba

Kenji Okamoto

Hiroki Uede

Yasuharu Shingai

Wataru Nagoh

Keigo Aihara

Hirofumi Konno

The problem to be solved by the present invention is to provide an oxygen storage and release material comprising a ceria-zirconia-based complex oxide improved in ability to remove HC and NOx and a three-way catalyst able to reduce an amount of NOx emission. Further, to solve this problem, an oxygen storage and release material comprising a ceria-zirconia-based complex oxide containing GdOin 0.1 mol % or more and less than 20 mol % and having an ion conductivity of 2&#xd7;10S/cm or more at 400&#xb0; C. is provided. Further, in addition to the above, an oxygen storage and release material having a molar ratio of cerium and zirconium of 0.2 or more and 0.6 or less by cerium/(cerium+zirconium) and an speed of oxygen storage and release '&#x394;t' of 20.0 seconds or more or amount of oxygen storage and release of 300 &#x3bc;mol-O/g or more etc. was obtained. Further, by applying the oxygen storage and release material to the catalyst, it is possible to assist the purification of exhaust gas as it changes every instant in accordance with the driving conditions and possible to obtain a catalyst with a higher ability to remove harmful components of catalytic precious metals than before. In particular, it is possible to obtain an automotive exhaust gas purification system excellent in ability to remove CO, NOx, and HC.

Oxygen storage and release material, catalyst, exhaust gas purification system, and exhaust gas treatment method

A ceria-zirconia-based composite oxide oxygen storage material with a fast oxygen storage rate having an OSC ability enabling fast response to changes in exhaust gas which does not greatly fluctuate in composition, but varies at a fast rate near the stoichiometric air-fuel ratio, an exhaust gas purification catalyst, and a honeycomb structure for exhaust gas purification are provided. A ceria-zirconia-based composite oxide oxygen storage material, which oxygen storage material has a molar ratio of cerium and zirconium, by cerium/(cerium+zirconium), of 0.33 to 0.90, has an ion conductivity measured by an AC impedance method of 1&#xd7;10S/cm or more at 400&#xb0; C., and contains metal ions M of one or more types of rare earth elements selected from Sm, Eu, Pr, Gd, and Dywith a coordination number of over 7.0 in an amount of 0.5 mol % to 15 mol % with respect to the total amount of cations.

Ceria-zirconia-based composite oxide oxygen storage material, exhaust gas cleaning catalyst, and honeycomb structure for exhaust gas cleaning

A ceria-zirconia-based composite oxide which has a crystal phase of the composite oxide of a single solid-solution phase even after exposure to a high temperature over a long time and has a small change in mode pore diameter and in pore volume before and after a high temperature durability test is provided. This is realized by a ceria-zirconia-based composite oxide having a chemical composition, by mass ratio, of zirconia: 30% to 80%, a total of oxides of one or more elements selected from yttrium and rare earth elements having atomic number 57 to 71 (except cerium and promethium): 0% to 20%, and a balance of ceria and unavoidable impurities, in which ceria-zirconia-based composite oxide, the composite oxide is deemed to be a single solid-solution phase in an X-ray diffraction pattern after a durability test which heats the oxide in the atmosphere at a temperature condition of 1100&#xb0; C. for 5 hours and has a ratio (b/a) of mode pore diameter (b) of a pore distribution after a durability test which heats the oxide in the atmosphere at a temperature condition of 1100&#xb0; C. for 5 hours to the mode pore diameter (a) before the durability test of 1.0&#x2264;b/a&#x2264;2.0 and/or has a ratio (d/c) of pore volume (d) after a durability test which heats the oxide in the atmosphere at a temperature condition of 1100&#xb0; C. for 5 hours to the pore volume (c) before the durability test of 0.20&#x2264;d/c&#x2264;1.00.

Ceria-zirconia-based composite oxide and method of production of the same

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Anan, Japan

Tomoharu Itoh