Rhodia Operations

Keiichiro Mitsuoka

Naotaka Ohtake

Kazuhiko Yokota

Provided are: a complex oxide that exhibits high redox ability even at low temperatures, has excellent heat resistance, and stably retains these characteristics even on repeated oxidation and reduction at high temperature; a method for producing the same; and an exhaust gas purification catalyst. The inventive complex oxide contains more than 0 but no more than 20 parts by mass of Si, calculated as SiO, per total 100 parts by mass of rare earth metal elements including Ce, calculated as oxides; and has a characteristic such that when it is subjected to temperature-programmed reduction (TPR) measurement in a 10% hydrogen-90% argon atmosphere at from 50&#xb0; C. to 900&#xb0; C. with the temperature increasing at a rate of 10&#xb0; C./min, followed by oxidation treatment at 500&#xb0; C. for 0.5 hours, and then temperature-programmed reduction measurement is performed again, its calculated reduction rate at and below 400&#xb0; C. is at least 1.5%.

Complex oxide, method for producing same, and exhaust gas purification catalyst

Provided are: a complex oxide that exhibits high redox ability even at low temperatures, has excellent heat resistance, and stably retains these characteristics even on repeated oxidation and reduction at high temperature; a method for producing the same; and an exhaust gas purification catalyst. The inventive complex oxide contains Ce; rare earth metal element other than Ce, including Y; Al and/or Zr; and Si; such that the Ce, and said other elements other than Ce and Si, are present in a mass ratio of 85:15-99:1, calculated as oxides; and has a characteristic such that when it is subjected to temperature-programmed reduction (TPR) measurement in a 10% hydrogen-90% argon atmosphere at from 50&#xb0; C. to 900&#xb0; C. with the temperature increasing at a rate of 10&#xb0; C./min, followed by oxidation treatment at 500&#xb0; C. for 0.5 hours, and then temperature-programmed reduction measurement is performed again, its calculated reduction rate at and below 400&#xb0; C. is at least 2.0%.

Growing community of inventors

Tokushima, Japan

Keiichiro Mitsuoka