Abstract:
An exhaust gas-purifying catalyst includes first particles of oxygen storage material, second particles of one or more rare-earth elements other than cerium and/or compounds thereof 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 the rare-earth element(s) 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 0.68 or more.
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 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:
Disclosed is a catalyst composition containing a composite oxide. The composite oxide contains a transition element (excluding platinum group elements) which is transformed into a solid solution in the composite oxide under an oxidizing atmosphere and is precipitated from the composite oxide under a reducing atmosphere.
Abstract:
To provide a heat-resistant oxide which is excellent in heat resistance and durability at high temperature and has high activity, a heat-resistant oxide which has an oxide crystal structure and in which a rate of a solid solution of a noble metal in the oxide crystal structure is 50% or more is obtained by heat-treating (secondarily baking) a precursor composition comprising zirconia, at least one coordinative element selected from the group consisting of rare earth elements, alkaline earth elements, aluminum and silicon, and at least one noble metal selected from the group consisting of platinum, rhodium and palladium at 650° C. or higher.
Abstract:
An exhaust gas-purifying catalyst is less prone to cause a decrease in its activity even when used in a high temperature atmosphere containing oxygen at a high concentration. The exhaust gas-purifying catalyst includes a composite oxide and Pd or a second solid solution of a composite and Rh and/or Pt. The first and second solid solutions have perovskite structure and are represented by ABO3 and CDO3, respectively. The composite oxide catalyst is supported by a composite oxide support including a composite oxide of spinel structure represented by EF2O4 or a composite oxide represented by GAl12O19. A and B represent a rare-earth element and a transition element, respectively. C and G represent an alkaline-earth element. D represents one or more of Ti, Zr, Hf and Ce. E represents an alkaline-earth element and/or a transition element. F represents one or more of Al, Mg and transition elements.
Abstract:
An object of the present invention is to provide an exhaust gas-purifying catalyst that is less prone to cause a decrease in its activity even when used at high temperatures in an atmosphere whose oxygen concentration is high. An exhaust gas-purifying catalyst of the present invention includes a composite oxide of alkaline-earth metal and aluminum, and platinum, wherein at least a part of the composite oxide and at least a part of the platinum forms a solid solution.
Abstract:
To provide a heat-resistant oxide which is excellent in heat resistance and durability at high temperature and has high activity, a heat-resistant oxide which has an oxide crystal structure and in which a rate of a solid solution of a noble metal in the oxide crystal structure is 50% or more is obtained by heat-treating (secondarily baking) a precursor composition comprising zirconia, at least one coordinative element selected from the group consisting of rare earth elements, alkaline earth elements, aluminum and silicon, and at least one noble metal selected from the group consisting of platinum, rhodium and palladium at 650° C. or higher.
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 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.