An exhaust gas purification catalyst includes: a first catalyst unit that consists of a hydrogen generating catalyst including a noble metal and an oxide that contains lanthanum, zirconium and an additional element such as neodymium; a second catalyst unit that consists of an oxygen storage/release material and a perovskite oxide disposed in contact with the oxygen storage/release material and represented by the general formula La.sub.xM1.sub.1-xM2O.sub.3-δ, where La is lanthanum, M1 is at least one element selected from the group consisting of barium (Ba), strontium (Sr) and calcium (Ca), M2 is at least one element selected from the group consisting of iron (Fe), cobalt (Co) and manganese (Mn), x satisfies 0<x≦1, and δ satisfies 0≦δ≦1; and a holding material that holds the first catalyst unit and the second catalyst unit in a mutually separated state.

A NO.sub.x adsorber catalyst and its use in an emission treatment system for internal combustion engines, is disclosed. The NO.sub.x adsorber catalyst composition comprises a support material, one or more platinum group metals disposed on the support material, and a NO.sub.x storage material.

Disclosed are a composite oxide which is capable of maintaining a large volume of pores even used in a high temperature environment, and which has excellent heat resistance and catalytic activity, as well as a method for producing the composite oxide and a catalyst for exhaust gas purification employing the composite oxide. The composite oxide contains cerium and at least one element selected from aluminum, silicon, or rare earth metals other than cerium and including yttrium, at a mass ratio of 85:15 to 99:1 in terms oxides, and has a property of exhibiting a not less than 0.30 cm.sup.3/g, preferably not less than 0.40 cm.sup.3/g volume of pores with a diameter of not larger than 200 nm, after calcination at 900° C. for 5 hours, and is suitable for a co-catalyst in a catalyst for vehicle exhaust gas purification.

[Problem] Provided is an exhaust gas purification catalyst capable of exhibiting even higher exhaust gas purification performance without impairing Pd catalytic activity, and an exhaust gas purification system using the exhaust gas purification catalyst.

[Solution] Provided is an exhaust gas purification catalyst comprising a substrate and a catalyst layer provided on the substrate, said catalyst having a first section located upstream along a flow direction of the exhaust gas and a second section located downstream from the first section; the catalyst layer in the first section comprises a first catalyst layer comprising palladium and a second catalyst layer comprising rhodium and covering the first catalyst layer, wherein a pore volume proportion is 12% or more and less than 18% wherein the pore volume proportion is a proportion of a total volume of the pores, which have a pore diameter of 0.06 μm to 30.0 μm as measured by mercury press-in method and existing in the substrate and the catalyst layer in the first section to a volume of a entire first section; and a wash coat amount is 100 g/L to 190 g/L, wherein a wash coat amount is a mass per unit volume of the catalyst layer in the first section to the volume of the substrate existing in the first section.

The present invention provides an exhaust gas purifying catalyst including a first catalyst layer (12). The first catalyst layer (12) includes a first section (14) and a second section (15) in an exhaust gas flow direction, the first section (14) being located on an upstream side in the exhaust gas flow direction relative to the second section (15). The first section (14) and the second section (15) both contain a catalytically active component including a specific element. A concentration of the specific element is higher in the first section (14) than in the second section (15). A concentration gradient of the specific element contained in the first section (14) in a thickness direction of the catalyst layer (12) is milder than a concentration gradient of the specific element contained in the second section (15) in the thickness direction.

The present invention discloses a rare-earth-manganese/cerium-zirconium-based composite compound, a method for preparing the same, and a use thereof. The composite compound is of a core-shell structure with a general formula expressed as: A RE.sub.cB.sub.aO.sub.b-(1-A)Ce.sub.xZr.sub.(1-x-y)M.sub.yO.sub.2-z, wherein 0.1≤A≤0.3, preferably 0.1≤A≤0.2; a shell layer has a main component of rare-earth manganese oxide with a general formula of RE.sub.cMn.sub.aO.sub.b, wherein RE is a rare-earth element or a combination of more than one rare-earth elements, and B is Mn or a combination of Mn and a transition metal element, 1≤a≤8, 2≤b≤18, and 0.25≤c≤4; and a core has a main component of cerium-zirconium composite oxide with a general formula of Ce.sub.xZr.sub.(1-x-y)M.sub.yO.sub.2-z, wherein M is one or more non-cerium rare-earth elements, 0.1≤x≤0.9, 0≤y≤0.3, and 0.01≤z≤0.3. The composite compound enhances an oxygen storage capacity of a cerium-zirconium material through an interface effect, thereby increasing a conversion rate of a nitrogen oxide.

A NO.sub.x adsorber catalyst and its use in an emission treatment system for internal combustion engines, is disclosed. The NO.sub.x adsorber catalyst composition comprises a support material, one or more platinum group metals disposed on the support material, and a NO.sub.x storage material.

It is intended to provide a novel zeolite with a rare earth element-substituted framework which has a higher amount of NOx adsorbed and a method for producing the same, and a NOx adsorption member and a catalyst for automobile exhaust gas, etc. comprising the same. The present invention provides a zeolite with a rare earth element-substituted framework, comprising at least a zeolite and at least one rare earth element selected from the group consisting of Ce, La, Nd and Pr, wherein a content ratio of the rare earth element is 1 to 15% by mass in total based on the total amount, and one or some of Al and/or Si atoms constituting the framework of the zeolite are replaced with the rare earth element.

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 comprising an inlet end and an outlet end with an axial length L; a first catalytic region comprising a first platinum group metal (PGM) component supported on a first PGM support material, wherein the first PGM component comprises rhodium (Rh) and platinum (Pt); and wherein Pt and Rh has a weight ratio of at least 1:10.

An exhaust gas purifying catalyst having first carrier particles, second carrier particles, and precious metal catalyst particles supported on the first and second carrier particles, wherein: the first carrier particles contain ceria, zirconia, and a rare-earth oxide other than ceria; the second carrier particles contain a rare-earth oxide other than ceria, and may contain ceria and zirconia; the contained proportion of ceria and zirconia in the first carrier particles is higher than the contained proportion of ceria and zirconia in the second carrier particles; the contained proportion of the rare-earth oxide in the second carrier particles is higher than the contained proportion of the rare-earth oxide in the first carrier particles; and the contained proportion of ceria in the first carrier particles is 45 wt % or less, while the precious metal catalyst particles include rhodium particles.