A NO.sub.x trap catalyst is disclosed. The NO.sub.x trap catalyst comprises a noble metal, a NO.sub.x storage component, a support, and a first ceria-containing material. The first ceria-containing material is pre-aged prior to incorporation into the NOx trap catalyst, and may have a surface area of less than 80 m.sup.2/g. The invention also includes exhaust systems comprising the NO.sub.x trap catalyst, and a method for treating exhaust gas utilizing the NO.sub.x trap catalyst.

A controlling device for purifying exhaust gas includes: a fuel cutting controller (2) that, if a predetermined condition for fuel cutting is satisfied, shuts off supply of fuel to an engine (10) after a predetermined delay time (B) elapses; a calculator (3) that calculates oxygen occludability of a catalyst (6, 7) being interposed in an exhaust system of the engine (10) and containing an oxygen occludable material; and a setter (4) that sets a length of the delay time (B) in accordance with the oxygen occludability calculated by the calculator (3).

An object of the present invention is to provide an exhaust gas purification system which exhibits high exhaust gas purification performance. The present invention provides an exhaust gas purification system including: a carrier containing aluminum oxide; an exhaust gas purification device including a catalyst provided on the carrier and containing gallium, and connected to an internal combustion engine; and a system connected to the exhaust gas purification device for increasing an oxygen concentration. The system for increasing an oxygen concentration provides an oxygen concentration higher than that of a post combusted gas of the internal combustion engine.

This disclosure is directed to catalyst compositions, catalytic articles for purifying exhaust gas emissions and methods of making and using the same. In particular, the disclosure relates to a catalytic article including a catalytic material on a substrate, wherein the catalytic material has a first layer and a second layer. The first layer provides effective lean NO.sub.x trap functionality and the second layer provides effective three-way conversion of carbon monoxide, hydrocarbons, and nitrogen oxides (NO.sub.x).

A NO.sub.x absorber catalyst for treating an exhaust gas from a diesel engine. The NO.sub.x absorber catalyst comprises a first NO.sub.x absorber material comprising a molecular sieve catalyst, wherein the molecular sieve catalyst comprises a noble metal and a molecular sieve, and wherein the molecular sieve contains the noble metal; a second NO.sub.x absorber material comprising palladium (Pd) supported on an oxide of cerium; and a substrate having an inlet end and an outlet end.

Provided is a novel exhaust gas purification catalyst, which uses a Cu-based delafossite oxide, capable of increasing the exhaust gas purification performance compared to the case of using the Cu-based delafossite oxide alone. Proposed is an exhaust gas purification catalyst comprising a delafossite-type oxide represented by a general formula ABO.sub.2 and an inorganic porous material, wherein Cu is contained in the A site of the general formula of the delafossite oxide, one or two or more elements selected from the group consisting of Mn, Al, Cr, Ga, Fe, Co, Ni, In, La, Nd, Sm, Eu, Y, V, and Ti are contained in the B site thereof, and Cu is contained in 3 to 30% relative to the total content (mass) of the delafossite-type oxide and the inorganic porous material.

An oxygen storage material comprises a LaCoAl-based composite oxide containing lanthanum, cobalt and aluminum. The LaCoAl-based composite oxide is in a form in which at least part of the aluminum is solid-dissolved in a LaCo composite oxide having a perovskite structure, and has a composition expressed by the following chemical formula (1):

LaCo.sub.yAl.sub.xO.sub.(1)

where x and y are numbers satisfying conditions of 0<x <1 and 0<y<1, where x+y=0.5 to 1.5, and is a number of 1.5 to 4.5.

Disclosed is a gas sensor element having an electrode containing a first metal as a predominant component and a lead containing a second metal as a predominant component. The electrode and the lead are connected directly at a connection boundary thereof, or connected indirectly via a connection joint. The connection boundary or joint includes a component region where either one of the first and second metals lower in specific gravity than the other of the first and second metals is contained in an amount ranging between those in the electrode and the lead.

An arrangement structure of an exhaust gas sensor includes an exhaust pipe that extends from an engine for a vehicle to form a part of an exhaust flow path, a catalytic device that purifies exhaust gas flowing through the exhaust flow path, and a first exhaust gas sensor that detects a predetermined component in the exhaust gas. The exhaust pipe is led out from a front side of the engine to one side in a left-right direction of the engine, and extends rearward so as to be routed on a lateral side of the engine. The catalytic device is arranged in the middle of the exhaust pipe on the lateral side of the engine. The first exhaust gas sensor is arranged on the lateral side of the engine and on an upstream side or a downstream side of the catalytic device in the exhaust pipe.

An exhaust purification system includes an LAF sensor provided in an exhaust pipe and generates a signal corresponding to an air-fuel ratio of exhaust gas. An upstream catalytic converter is downstream of the LAF sensor and has a catalyst to purify the exhaust gas. An O2 sensor is downstream of the upstream catalytic converter, and generates a signal corresponding to the air-fuel ratio of the exhaust gas. A GPF is downstream of a the O2 sensor and purifies the exhaust gas. An ECU controls an air-fuel mixture in an engine using output signal KACT of the LAF sensor and an output signal VO2 of the O2 sensor such that the air-fuel ratio of exhaust gas flowing into the GPF converges to a target value near the stoichiometric ratio. The GPF has a filter substrate and a downstream TWC supported by a partition of the filter substrate.