Patent attributes
An exhaust gas purification catalyst is provided with a substrate and a catalyst coating layer formed on the surface of the substrate. The catalyst coating layer is formed into a layered structure having upper and lower layers, with a lower layer being closer to the surface of the substrate and an upper layer being relatively farther therefrom. The catalyst coating layer is provided with Rh and Pd as precious metal catalysts and is provided with an OSC material having an oxygen storage capacity as a support. The Rh is disposed in the upper layer of the catalyst coating layer, and the Pd is disposed in both the upper layer and the lower layer of the catalyst coating layer. At least a portion of the Pd in the upper layer and in the lower layer is supported on the OSC material. The mass ratio of the Pd disposed in the upper layer to the Pd disposed in the lower layer is not more than 0.4.
