EXHAUST GAS PURIFICATION CATALYST

WIPO Patent Application WO/2023/171528

A1

The present invention provides an exhaust gas purification catalyst which is provided with an NOx absorption layer and which has excellent NOx purification performance. The disclosed exhaust gas purification catalyst comprises a substrate and a catalyst layer. The catalyst layer comprises a lower layer, a middle layer and an upper layer. The lower layer contains a catalyst metal. The upper layer contains Rh. The middle layer has a front portion positioned on an upstream side in a direction of flow of exhaust gas, and a rear portion positioned on a downstream side. Each of the front portion and the rear portion contains Pt and a NOx absorbing material. The NOx absorbing material includes at least one type of NOx absorbing element selected from the group comprising alkali metal elements and alkaline earth metal elements. A ratio (CA/CB) of a concentration (CA) of the NOx absorbing element contained in the front portion per 1 L of the substrate to a concentration (CB) of the NOx absorbing element contained in the rear portion per 1 L of the substrate satisfies the relationship 0