Patent ID: 11154842

Abstract:
An exhaust gas purification underfloor catalyst characterized in having a catalyst layer having a lower layer and an upper layer, the lower layer containing alumina and CeO2, the noble metal content of the lower layer being at most 0.5 mass % in relation to the mass of the lower layer, the upper layer containing Rh, alumina, and CeO2, the amount of noble metals other than Rh contained being 1 mol % or less in relation to the total amount of noble metals contained in the upper layer, the total amount of CeO2 contained in the lower layer and the upper layer being 14 g/L to 30 g/L, the amount of CeO2 contained in the upper layer being 7 g/L to 25 g/L, and the amount of CeO2 contained in the lower layer being 20% or more of the amount of CeO2 contained in the upper layer.