A three-way catalyst article, and its use in an exhaust system for internal combustion engines, is disclosed. The catalyst article for treating exhaust gas comprising: a substrate; and a first catalytic region on the substrate; wherein the first catalytic region comprises a first platinum group metal (PGM) component, wherein the first PGM component comprises PGM nanoparticles, wherein the PGM nanoparticles have an average particle size of about 1 to about 20 nm with a standard deviation (SD) no more than 1 nm.

Disclosed herein are monolith oxidation catalysts for the destruction of CO and volatile organic compounds (VOC) chemical emissions, in particular, the destruction of light alkane organic compounds. The catalysts contain high surface area refractory oxides of silica- and hafnia-doped zirconia and silica, or tin oxide or stabilized alumina; and at least one platinum group metals, in particular platinum metal, or a combination of platinum and palladium.

The present disclosure provides an exhaust gas purification material and an exhaust gas purification device that can efficiently remove harmful components even after being exposed to high temperature. Such exhaust gas purification material comprises metal oxide particles and noble metal particles supported on the metal oxide particles. The noble metal particles have a particle size distribution with a mean of 1.5 nm and 18 nm and a standard deviation of less than 1.6 nm.

A ceramic honeycomb structure comprising large numbers of cells partitioned by porous cell walls, the cell walls having (a) porosity of 50-80%, and when measured by mercury porosimetry, (b) a median pore diameter being 25-50 μm, (c) (i) a cumulative pore volume in a pore diameter range of 20 μm or less being 25% or less of the total pore volume, (ii) a cumulative pore volume in a pore diameter range of more than 20 μm and 50 μm or less being 50% or more of the total pore volume, and (iii) a cumulative pore volume in a pore diameter range of more than 50 μm being 12% or more of the total pore volume.

A ceramic honeycomb structure comprising large numbers of cells partitioned by porous cell walls, the cell walls having (a) porosity of 50-80%, and when measured by mercury porosimetry, (b) a median pore diameter being 25-50 μm, (c) (i) a cumulative pore volume in a pore diameter range of 20 μm or less being 25% or less of the total pore volume, (ii) a cumulative pore volume in a pore diameter range of more than 20 μm and 50 μm or less being 50% or more of the total pore volume, and (iii) a cumulative pore volume in a pore diameter range of more than 50 μm being 12% or more of the total pore volume.

The present invention relates to a catalyst comprising two layers on an inert catalyst carrier, wherein a layer A lying directly on the catalyst carrier contains at least one platinum group metal and one cerium/zirconium/SE mixed oxide, and a layer B, applied on layer A and in direct contact with the flow of exhaust gas, contains at least one platinum group metal and a cerium/zirconium/SE mixed oxide, wherein SE stands for a rare earth metal other than from cerium, characterized in that the fraction of SE oxide in the cerium/zirconium/SE mixed oxide of layer A is less than the fraction of SE oxide in the cerium/zirconium/SE mixed oxide of layer B.

The present invention relates to a catalyst comprising two layers on an inert catalyst carrier, wherein a layer A lying directly on the catalyst carrier contains at least one platinum group metal and one cerium/zirconium/SE mixed oxide, and a layer B, applied on layer A and in direct contact with the flow of exhaust gas, contains at least one platinum group metal and a cerium/zirconium/SE mixed oxide, wherein SE stands for a rare earth metal other than from cerium, characterized in that the fraction of SE oxide in the cerium/zirconium/SE mixed oxide of layer A is less than the fraction of SE oxide in the cerium/zirconium/SE mixed oxide of layer B.

A catalyst for purification of exhaust gas including a substrate, and a catalyst coat layer which is formed on a surface of the substrate and contains catalyst particles, wherein the catalyst coat layer has an average thickness ranging 25 to 150 μm, a void fraction, as determined by scanning electron microscope observation of a cross-section of the catalyst coat layer, ranging 1.5 to 8.0% by volume, 60 to 90% by volume of all voids in the catalyst coat layer are high-aspect ratio pores which have equivalent circle diameters ranging 2 to 50 μm in a cross-sectional image of a cross-section of the catalyst coat layer perpendicular to a flow direction of exhaust gas in the substrate, and which ratios of 5 or higher, the high-aspect ratio pores have an average aspect ratio ranging 10 to 50, and a noble metal is supported on the entire catalyst coat layer.

A catalyst for purification of exhaust gas including a substrate, and a catalyst coat layer which is formed on a surface of the substrate and contains catalyst particles, wherein the catalyst coat layer has an average thickness ranging 25 to 150 μm, a void fraction, as determined by scanning electron microscope observation of a cross-section of the catalyst coat layer, ranging 1.5 to 8.0% by volume, 60 to 90% by volume of all voids in the catalyst coat layer are high-aspect ratio pores which have equivalent circle diameters ranging 2 to 50 μm in a cross-sectional image of a cross-section of the catalyst coat layer perpendicular to a flow direction of exhaust gas in the substrate, and which ratios of 5 or higher, the high-aspect ratio pores have an average aspect ratio ranging 10 to 50, and a noble metal is supported on the entire catalyst coat layer.

The exhaust gas-purifying catalyst of the invention contains oxide particles having interdispersed therein A crystallites that are loaded with a noble metal and B crystallites that are not loaded with a noble metal. The A crystallites loaded with a noble metal are composed of an oxide containing at least one of zirconium (Zr) and cerium (Ce). The B crystallites not loaded with a noble metal are composed of a cerium (Ce)-containing oxide which has a higher Ce content (mol %) than the oxide making up the A crystallites. The oxide particles have a specific surface area after 5 hours of heat treatment at 1,150° C. in open air of 30 m.sup.2/g or more.