Exhaust-gas purifying catalyst and manufacturing method therefor
AssigneeCataler Corporation
InventorsTakara Misumi, Satoshi Matsueda
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Abstract
An exhaust-gas purifying catalyst includes a lower layer containing ceria-based oxide particles and an upper layer containing metal oxide particles and a precious metal supported on the metal oxide particles, wherein the exhaust-gas purifying catalyst is characterized in that the Rh content of the lower layer is equal to or less than 0.25 g/L, and also that the particle-size distribution of the ceria-based oxide particles in the lower layer, which is obtained by scanning electron microscopy, has a first peak in which the peak top thereof is in a region of 0.90-6.50 μm and a second peak in which the peak top thereof is in a region of 9.50-34.0 μm.
Claims9
An exhaust gas purification catalyst, comprising a lower layer containing ceria-based oxide particles and an upper layer containing metal oxide particles and a precious metal supported on the metal oxide particles, wherein
- the Rh content of the lower layer is not more than 0.25 g/L, and
- a particle-size distribution of the ceria-based oxide particles in the lower layer, as obtained by scanning electron microscopy, has a first peak in which a peak top thereof is in a region of 0.90 to 6.50 μm and a second peak in which the peak top thereof is in a region of 9.50 to 34.0 μm.
A method for the production of an exhaust gas purification catalyst, comprising the steps of:
- forming, on a substrate, a lower layer containing first ceria-based oxide particles having a peak top in a region of 0.90 to 6.50 μm and second ceria-based oxide particles having a peak top in the region of 9.50 to 34.0 μm, in a particle diameter distribution obtained by scanning electron microscopy, and
- forming an upper layer containing metal oxide particles and a precious metal supported on the metal oxide particles.
A method for the production of an exhaust gas purification catalyst, comprising the steps of:
- forming a substrate,
- forming, on the substrate, an upper layer containing metal oxide particles and a precious metal supported on the metal oxide particles, wherein
- a part or all of the substrate is composed of a lower layer containing first ceria-based oxide particles having a peak top in a region of 0.90 to 6.50 μm and second ceria-based oxide particles having a peak top in the region of 9.50 to 34.0 μm, in a particle diameter distribution obtained by scanning electron microscopy.
Dependencies are inferred from the claim text.