EXHAUST GAS PURIFICATION CATALYST

摘要

PROBLEM TO BE SOLVED: To provide an exhaust gas purification catalyst satisfying both an oxygen suctioning/discharging function and NOx purification performance and having high performance.SOLUTION: An exhaust gas purification catalyst contains a ceria-zirconia based complex oxide containing at least one additional element selected from a group consisting of praseodymium, lanthanum and yttrium of 0.5 to 5.0 mol% with respect to a total amount of total cation, having a molar ratio of (cerium +the additional element):(zirconium) falling in a range of 43:57 to 48:52 and having a pyrochlore type regular arrangement structure in a region of an exhaust gas upstream side of a catalyst coating layer.SELECTED DRAWING: Figure 2