CERIA-ZIRCONIA-BASED COMPLEX OXIDE, PRODUCTION METHOD THEREOF AND CATALYST FOR EXHAUST GAS PURIFICATION USING THE CERIA-ZIRCONIA-BASED COMPLEX OXIDE

摘要

PROBLEM TO BE SOLVED: To provide a ceria-zirconia-based complex oxide which exhibits an excellent oxygen storage capacity (OSC) even after long-time exposure to high temperatures and a catalyst for exhaust gas purification using the same.SOLUTION: A ceria-zirconia-based complex oxide contains a total content of 0.1-4.0 at% of at least one rare earth element selected from lanthanum, yttrium and praseodymium, and 90 at% or more of the whole amount of the rare earth element is contained in a region close to a surface, or in a range of 50 nm or smaller from the surface of the primary particle of the complex oxide. A content ratio of the complex oxide is 43:57 to 48:52 in terms of the mol ratio of [cerium]:[zirconium]; an average particle size of the primary particle is 2.2-4.5 μm; and an intensity ratio {I(14/29) value} of diffraction lines at 2&thetas;=14.5° and 2&thetas;=29° and the intensity ratio {I(28/29) value} of diffraction lines at 2&thetas;=28.5° and 2&thetas;=29° in the X-ray diffraction pattern satisfies relationships of I(14/29) value≥0.02 and I(28/29) value≤0.08.