Abstract:
An exhaust gas-purifying catalyst includes first particles of oxygen storage material, second particles of one or more alkaline-earth metal elements and/or compounds thereof interposed between the first particles, and third particles of one or more precious metal elements interposed between the first particles. A spectrum of a first characteristic X-ray intensity for one of the one or more alkaline-earth metal elements and a spectrum of a second characteristic X-ray intensity for one of the one or more precious metal elements that are obtained by performing a line analysis using energy-dispersive X-ray spectrometry along a length of 500 nm have a correlation coefficient σ(AE,PM) of 0.70 or more.
Abstract:
An exhaust gas-purifying catalyst includes a substrate, and a catalytic layer supported by the substrate. The catalytic layer includes a support made of alumina, an oxygen storage material, an alkaline earth metal and/or a compound of alkaline-earth metal selectively supported by a surface of the support and dispersed on the surface of the support, and a precious metal supported by the surface of the support. A ratio of a number of moles of the alkaline-earth metal in the catalytic layer with respect to a volumetric capacity of the exhaust gas-purifying catalyst falls within a range of 0.0004 mol/L to 0.35 mol/L.
Abstract:
An exhaust gas-purifying catalyst according to the present invention includes a substrate, a first catalytic layer facing the substrate and includes at least one precious metal selected from the group consisting of palladium and platinum, and alumina doped with an alkaline-earth metal element, and a second catalytic layer facing the substrate with the first catalytic layer interposed therebetween or intervening between the substrate and the first catalytic layer, the second catalytic layer includes rhodium and alumina doped with the alkaline-earth metal element.
Abstract:
An exhaust gas-purifying catalyst whose activity is less prone to be decreased even in the case where used in a high-temperature atmosphere containing oxygen at a high concentration can be realized. The catalytic layer of the catalyst includes an oxide particle, a simple oxide of alkaline-earth element or rare-earth element, and alumina and/or aluminum hydroxide. The oxide particle contains an oxide of rare-earth element and/or zirconium, a composite oxide and a precious metal. The composite oxide contains an alkaline-earth element and at least one of the rare-earth element and zirconium. The composite oxide and a part of the precious metal form a solid solution.
Abstract:
An exhaust gas-purifying catalyst (1) contains a rare-earth element, an alkaline-earth element, zirconium and a precious metal, wherein an atomic ratio of the alkaline-earth element with respect to a sum of the rare-earth element and the zirconium is 10 atomic % or more, a part of the rare-earth element and a part of zirconium form a composite oxide with at least a part of the alkaline-earth element, and the composite oxide and a part of the precious metal form a solid solution.
Abstract:
An object of the present invention is to provide a catalyst composition containing a perovskite-type composite oxide which exhibits a satisfactory catalytic performance over a long time even in a high temperature atmosphere and has a stable quality in which Rh and/or Pt dissolves to form a solid solution at a high rate.To achieve the object described above, in the present invention the catalyst composition is prepared to comprise an Rh-containing perovskite-type composite oxide represented by the following general formula (I) and/or a Pt-containing perovskite-type composite oxide represented by the following general formula (II) and a thermostable oxide optionally containing a noble metal. A1xA2wB11−(y+z)B2yRhzO3±δ (I) A3rA4sB31−(t+u)B4tPtuO3±δ′ (II)
Abstract:
An exhaust gas-purifying catalyst includes a substrate, and a catalytic layer facing the substrate and including a precious metal, alumina, an oxygen storage material, and a sulfate of an alkaline-earth metal having an average particle diameter falling within a range of 0.01 to 0.70 μm, the average particle diameter being obtained by observation using a scanning electron microscope. Another exhaust gas-purifying catalyst includes a substrate, and a catalytic layer formed on the substrate using slurry containing a precious metal, alumina, an oxygen storage material, and a sulfate of an alkaline-earth metal having an average particle diameter falling within a range of 0.01 to 0.70 μm, the average particle diameter being obtained by observation using a scanning electron microscope.
Abstract:
An exhaust gas-purifying catalyst includes first particles of oxygen storage material, second particles of one or more acidic oxides interposed between the first particles, and third particles of one or more precious metal elements interposed between the first particles, wherein a spectrum of a characteristic X-ray intensity for one of constituent elements of the acidic oxide(s) other than oxygen and a spectrum of a characteristic X-ray intensity for one of the precious metal element(s) that are obtained by performing a line analysis using energy-dispersive X-ray spectrometry along a length of 500 nm have a correlation coefficient of 0.70 or more.
Abstract:
An exhaust gas-purifying catalyst includes first particles of oxygen storage material, second particles of one or more acidic oxides interposed between the first particles, and third particles of one or more precious metal elements interposed between the first particles, wherein a spectrum of a characteristic X-ray intensity for one of constituent elements of the acidic oxide(s) other than oxygen and a spectrum of a characteristic X-ray intensity for one of the precious metal element(s) that are obtained by performing a line analysis using energy-dispersive X-ray spectrometry along a length of 500 nm have a correlation coefficient of 0.70 or more.
Abstract:
The exhaust gas-purifying catalyst includes a first oxide particle with an oxygen storage capacity, one or more second oxide particles partially or entirely covering a surface of the first oxide particle and having an oxygen storage capacity lower than that of the first oxide particle, an average particle diameter Dav of the one or more second oxide particles being smaller than that of the first oxide particle, and precious metal particles supported on at least one of the second oxide particle.