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, wherein the first PGM component comprises Rh and Pt; a second catalytic region comprising a second PGM component, wherein the second PGM component comprises Pd; and wherein the first PGM component has a Pt to Rh ratio of at least 1:20.

A catalytic converter system having oxygen storage materials is disclosed and methods for determining whether to reactivate oxygen storage materials and monitoring failure events of the oxygen storage materials are also disclosed.

A nitrous oxide (N.sub.2O) removal catalyst composite is provided, comprising a N.sub.2O removal catalytic material on a substrate, the catalytic material comprising a rhodium (Rh) component supported on a ceria-based support, wherein the catalyst composite has a H.sub.2-consumption peak of about 100° C. or less as measured by hydrogen temperature-programmed reduction (H.sub.2-TPR). Methods of making and using the same are also provided.

According to a technique disclosed herein, provided is an exhaust gas purification catalyst, which both suppresses OSC when using a new vehicle and maintains OSC during life cycles. The exhaust gas purification catalyst disclosed herein is an exhaust gas purification catalyst includes a substrate, and a catalyst coated layer formed on the surface of the substrate, wherein the catalyst coated layer contains an OSC material having an oxygen storage capacity. The catalyst coated layer includes a Rh layer mainly containing Rh as a catalyst metal, and a Pd/Pt layer mainly containing Pd and/or Pt as a catalyst metal. At least a portion of the Pd/Pt layer in the catalyst coated layer contains, as the OSC material, a low specific surface area OSC material, including a ceria-zirconia composite oxide and having a specific surface area of 40 m.sup.2/g or more and 60 m.sup.2/g or less.

An gas purification catalyst device having a catalyst coated layer formed on at least one base material, wherein: the catalyst coated layer includes a first catalyst coated layer on the upstream side of an exhaust gas flow, and a second catalyst coated layer on the downstream side of the exhaust gas flow; the first catalyst coated layer includes a hydrocarbon adsorbent and a catalytic precious metal; and the second catalyst coated layer includes a nitrogen oxide adsorbent and a catalytic precious metal.

Described are a catalyst capable of effectively oxidizing an exhaust gas, a method for preparing the catalyst, and a method for oxidizing an exhaust gas using the catalyst. The exhaust gas oxidation catalyst includes at least two layers, a lower catalyst layer and an upper catalyst layer, laminated on a three-dimensional structure, wherein the lower catalyst layer and the upper catalyst layer independently contain precious metal and alumina and/or zeolite, and at least a part of the upper catalyst layer contains pores derived from a pore connecting agent with a combustion decomposition temperature of 300° C. or more to less than 450° C.

An exhaust gas purification including: a base of wall flow structure having inlet side cells wherein an end on the exhaust gas inflow side is open and outlet side cells wherein an end on the exhaust gas outflow side is open, and a porous partition wall that partitions the side cells; and first and second catalyst layers disposed in the interior of the porous partition wall so as to be in contact with the side cells, wherein either of the catalyst layers contains an oxidation catalyst but does not contain a reduction catalyst, and the other contains the reduction catalyst but does not contain the oxidation catalyst; and a ratio of the lengths of the catalyst layers differs between a surface of the porous partition wall on the side in contact with the inlet side cells and a surface on the side in contact with the outlet side cells.

The invention relates to a particulate filter for removing particles, carbon monoxide, hydrocarbons and nitrogen oxides out of the exhaust gas of combustion engines operated with stoichiometric air/fuel mixture, comprising a wall flow filter with length L and a coating Z, wherein the wall flow filter includes channels E and A which extend in parallel between a first and a second end of the wall flow filter and are separated by porous walls, which form surfaces OE or OA, and wherein the channels E are closed at the second end and the channels A are closed at the first end, characterised in that coating Z is located in the porous walls and extends from the first end of the wall flow filter over the entire length L, and includes active aluminum oxide, two different cerium/zirconium/rare earth metal mixed oxides and at least one platinum group metal.

A lean NO.sub.x trap catalyst and its use in an emission treatment system for internal combustion engines is disclosed. The lean NO.sub.x trap catalyst comprises a first layer for storing nitrogen oxides (NOx) under lean exhaust gas conditions and releasing and/or reducing stored NOx during rich exhaust gas conditions, and a second layer, said second layer comprising a first zone for oxidizing carbon monoxide (CO) and/or hydrocarbons (HC), and a second zone for oxidizing nitric oxide (NO), and a substrate having an inlet end and an outlet end.

An object of the present invention is to provide an exhaust gas purification catalyst which can exhibit sufficient purification performance even under a high Ga condition. The present invention relates to an exhaust gas purification catalyst comprising a substrate and a catalyst coating layer formed on the substrate, wherein the catalyst coating layer comprises catalyst particles, the catalyst coating layer having an upstream region extending by 40 to 60% of the entire length of the substrate from an upstream end of the catalyst in the direction of an exhaust gas flow and a downstream region corresponding to the remainder portion of the catalyst coating layer, the composition of the catalyst particle of the upstream region being different from that of the downstream region. The downstream region in the direction of an exhaust gas flow has a structure where a void is included in a large number, and furthermore high-aspect-ratio pores having an aspect ratio of 5 or more account for a certain percentage or more of the whole volume of voids. Thus, the exhaust gas purification catalyst exhibits enhanced purification performance.