An exhaust gas purification catalyst that has an excellent exhaust gas purification performance while suppressing pressure loss increases. The exhaust gas purification catalyst is provided with a substrate having a wall-flow structure and having a partition; a first catalyst layer formed, in a region of an interior part of the partition that is in contact with an entrance cell, along the extending direction of the partition from an exhaust gas inflow-side end for less than the total length L.sub.w of the partition; and a second catalyst layer formed, in a region of an interior part of the partition that is in contact with an exit cell, along the extending direction of the partition from the exhaust gas outflow-side end for less than the total length L.sub.w of the partition. The first catalyst layer and the second catalyst layer are configured to partially overlap with each other in the extending direction.

The exhaust gas purification device is provided with a wall flow structure substrate that has an entry-side cell, an exit-side cell and a porous partition, first catalyst parts which are formed in small pores having a relatively small pore diameter among internal pores in the partition, and second catalyst parts which are formed in large pores having a relatively large pore diameter among the internal pores in the partition. The first catalyst parts and the second catalyst parts each contain a carrier and at least one type of noble metal from among Pt, Pd and Rh supported on the carrier. The noble metal content in the first catalyst parts is smaller than the noble metal content in the second catalyst parts per 1 liter of substrate volume.

An object of the present invention is to provide an exhaust gas purification catalyst for purifying exhaust gas, in particular, fine composite-metal particles contained therein, and a method for producing the same; the exhaust gas purification catalyst according to the present invention includes fine composite-metal particles containing Rh and Pd, wherein, when the fine composite-metal particles in the exhaust gas purification catalyst are analyzed by STEM-EDX, the average ratio of the amount of Pd with respect to the total amount of Rh and Pd in the fine composite-metal particles is 1.7 atomic % or more and 24.8 atomic % or less.

Provided is an exhaust gas purification catalyst in which the performance of a catalyst metal can be brought out properly, the purification catalyst boasting excellent purification performance during warm-up of an internal combustion engine. The exhaust gas purification catalyst 10 is provided with a substrate 1 and a catalyst layer. A leading end section 1a positioned upstream in the direction of exhaust gas flow (arrow) has a portion in which the flow rate of exhaust gas is relatively high and a portion in which the flow rate of exhaust gas is relatively low during warm-up of the internal combustion engine. The catalyst, layer in the portion of relatively high flow rate of exhaust gas has a high density section 6 in which a noble metal, is supported at relatively high density. The high density section 6 is formed to be shorter than the total length of the exhaust gas purification catalyst 10 from the leading end section 1a in the direction of exhaust gas flow.

An exhaust gas purification catalyst having an excellent exhaust partition ability while reducing the increase in pressure loss. Exhaust gas purification catalyst includes a substrate having a wall-flow structure with partition wall, upstream coating section formed in portions of partition wall facing entrance cell, from exhaust inlet-side end in the extending direction of partition wall, and downstream coating section formed in portions of partition wall facing exit cell, from exhaust outlet-side end in the extending direction, having a length shorter than the entire length L.sub.w of the partition wall. In downstream coating section, a catalytic metal is concentrated in the surface layer in contact with exit cell.

An exhaust gas-purifying catalyst of the present invention comprises a substrate, and one or more catalytic layers provided on the substrate, wherein at least one of the catalytic layers (i) contains a precious metal, alumina, and an acidic oxide element, (ii) has a correlation coefficient ρ.sub.Al,AE of 0.70 or more, and (iii) has a correlation coefficient ρ.sub.PM,AE of 0.70 or more.

A catalysed filter for a positive ignition internal combustion engine comprises a porous filtering substrate having a total substrate length coated with a three-way catalyst washcoat composition comprising at least one precious metal selected from the group consisting of rhodium and one or both of platinum and palladium supported on a high surface area oxide, and an oxygen storage component, which composition being axially shared by a first zone comprising inlet surfaces of a first substrate length<total substrate length and a second zone comprising outlet surfaces of a second substrate length<total substrate length, wherein a sum of the substrate length in the first zone and the substrate length in the second zone≧100% and wherein one or both of the following applies: a washcoat loading in the first zone>second zone; and a total precious metal loading in the first zone>second zone.

Provided is a powder inorganic oxide containing Al, Ce and Zr as constituent elements, that affords a molded product with a density of 1.0 to 1.3 g/ml by placing 4.0 g of the inorganic oxide in a cylindrical container having diameter 20 mm and performing uniaxial molding under conditions of room temperature and pressure of 29.4 MPa for 30 sec., and achieves an average shrinkage percentage of not more than 14.0% as calculated by the following formula: average shrinkage percentage (%)=100×{(1−(c)/(a))+(1−(d)/(b))}/2 wherein each symbol is as defined in the DESCRIPTION.

Catalyst compositions, articles, systems and methods related to a three-way-catalyst composition comprising alumina doped with a transition metal.

A process for ring hydrogenation of a benzenepolycarboxylic acid or derivative thereof, includes contacting a feed stream comprising the acid or derivative thereof with a hydrogen containing gas in the presence of a catalyst under hydrogenation conditions to produce a hydrogenated product, wherein the catalyst contains rhodium and ruthenium.