Patent attributes
The exemplary embodiments relate to an exhaust gas purification catalyst that is excellent in terms of HC purification capacity and warm-up performance. Such exhaust gas purification catalyst comprises a substrate and a catalyst coating layer formed on the surface of the substrate, wherein the catalyst coating layer comprises an upper and lower layer comprising a lower layer being closer to the surface of the substrate and an upper layer being relatively remote from the surface of the substrate, the upper layer of the catalyst coating layer comprises Rh, Pd, and a carrier, the upper layer of the catalyst coating layer comprises an uppermost surface Pd layer having a Pd concentration relatively higher than that in any other portion in the upper layer within an area extending over a length of 20 mm or more from one end on the upstream side in the downstream direction on the surface of the upper layer, the lower layer of the catalyst coating layer comprises at least one noble metal selected from Pd and Pt and a carrier, and 60% or more of Pd by mass in the uppermost surface Pd layer exists in a layer up to 50% of the upper layer in a thickness direction from the surface of the uppermost surface Pd layer being relatively remote from the surface of the substrate.
