An exhaust purification system comprises an exhaust purification catalyst 20, an NO.sub.X sensor 46, air-fuel ratio sensor 41 downstream of the catalyst 20, and a control and diagnosis device. The device alternately sets a target air-fuel ratio to a rich air-fuel ratio and a lean air-fuel ratio and switches the target air-fuel ratio from the rich air-fuel ratio to the lean air-fuel ratio when the output air-fuel ratio of the air-fuel ratio sensor becomes a rich judged air-fuel ratio or less. The device diagnoses abnormality of the catalyst based on the output of the NO.sub.X sensor. It diagnoses abnormality of the catalyst when the air-fuel ratio of the exhaust gas flowing into the catalyst is a rich air-fuel ratio, but does not diagnose abnormality of the catalyst when the air-fuel ratio of the exhaust gas flowing into the catalyst is a lean air-fuel ratio.

The invention provides a catalyst composition, including a mixture of catalytically active particles and a magnetic material, such as superparamagnetic iron oxide nanoparticles, capable of inductive heating in response to an applied alternating electromagnetic field. The catalytically active particles will typically include a base metal, platinum group metal, oxide of base metal or platinum group metal, or combination thereof, and will be adapted for use in various catalytic systems, such as diesel oxidation catalysts, catalyzed soot filters, lean NOx traps, selective catalytic reduction catalysts, ammonia oxidation catalysts, or three-way catalysts. The invention also includes a system and method for heating a catalyst material, which includes a catalyst article that includes the catalyst composition and a conductor for receiving current and generating an alternating electromagnetic field in response thereto, the conductor positioned such that the generated alternating electromagnetic field is applied to at least a portion of the magnetic material.

Disclosed are passive NO.sub.x adsorbers and methods for synthesizing the same. Small-pore zeolitic materials with practical loadings of transition metals atomically dispersed in the micropores are described herein. Also demonstrated are simple and scalable synthesis routes to high loadings of atomically dispersed transition metals in the micropores of a small-pore zeolite.

There is provided: a NOx occlusion reduction-type catalyst that is provided in an exhaust passage of an internal combustion engine, occludes NOx in exhaust when the exhaust is in a lean state, and reduces and purifies the occluded NOx when the exhaust is in a rich state; an exhaust injector that is provided in the exhaust passage and is positioned further upstream than the NOx occlusion reduction-type catalyst; a NOx-purging control unit that performs NOx purging of reducing and purifying the NOx occluded in the NOx occlusion reduction-type catalyst by lowering the exhaust to a prescribed target lambda by fuel injection by the exhaust injector; and a NOx-purging-prohibition processing unit that inhibits performance of the NOx purging in a case where the exhaust cannot be lowered to the target lambda even if the fuel injection is performed at a maximum limit injection amount of the exhaust injector.

An NH.sub.3 supply amount controller reduces and adjusts a supply amount of NH.sub.3 to an SCR catalyst by an NH.sub.3 supplier, when an exhaust gas flowing into an NO.sub.X catalyst has a rich air-fuel ratio and NO.sub.X occluded by the NO.sub.X catalyst is reduced to N.sub.2. A reduction amount of the supply amount of the NH.sub.3 controlled by the NH.sub.3 supply amount controller is set smaller when a temperature of the NO.sub.X catalyst detected or estimated by an NO.sub.X catalyst temperature detector is higher.

The invention provides a selective catalytic reduction (SCR) catalyst effective in the abatement of nitrogen oxides (NOx), the SCR catalyst comprising a metal-promoted molecular sieve promoted with a metal selected from iron, copper, and combinations thereof, wherein the metal is present in an amount of 2.6% by weight or less on an oxide basis based on the total weight of the metal-promoted molecular sieve. A catalyst article, an exhaust gas treatment system method, and a method treating an exhaust gas stream, each comprising the SCR catalyst of the invention, are also provided. The SCR catalyst is particularly useful for treatment of exhaust from a lean burn gasoline engine.

The present invention relates to a method of making a support material composition comprising an Mg/Al oxide, a cerium oxide and at least another rare earth element oxide, to a support material composition and to the use of the support material composition as a nitrogen oxide storage component within a catalyst for treating exhaust gases to reduce NOx content.

The Invention relates to a nitrogen oxide storage catalyst composed of at least two catalytically-active washcoat layers on a support body, wherein a lower washcoat layer A comprises cerium oxide, an alkaline earth metal compound and/or an alkali compound, platinum and palladium, and manganese oxide, and an upper washcoat layer B disposed on the washcoat layer A comprises cerium oxide, platinum and palladium and does not contain any alkali and alkaline-earth compounds, and to a method for converting NO.sub.x in exhaust gases from motor vehicles which are operated with lean-burn engines.

The invention relates to a nitrogen oxide storage catalyst composed of at least two catalytically active washcoat layers on a support body, wherein a lower washcoat layer A comprises cerium oxide, an alkaline earth metal compound and/or an alkali compound, platinum and palladium, and an upper washcoat layer B located above washcoat layer A comprises cerium oxide, platinum and palladium, does not contain any alkali and alkaline-earth compounds, and has macropores. Also disclosed is a method for converting NOx in exhaust gases from motor vehicles operated with lean-burn engines.

Systems for abatement of pollutants in an exhaust gas stream of an internal combustion engine including a hydrogen injection article configured to introduce hydrogen upstream of a catalytic article are effective for the abatement of carbon monoxide and/or hydrocarbons and/or nitrogen oxides. The introduction of hydrogen may be intermittent and/or during a cold-start period.