Provided is a catalytic converter capable of obtaining superior NOx purification performance while reducing the amount of a noble metal catalyst. A catalytic converter 10 includes: a substrate 1 having a cell structure in which exhaust gas flows; and catalyst layers 3 that are formed on cell wall surfaces 2 of the substrate 1. The catalyst layers 3 include a first catalyst layer 4 disposed on an upstream side of the substrate 1 in an exhaust gas flow direction and a second catalyst layer 5 disposed on a downstream side of the substrate in the exhaust gas flow direction. The first catalyst layer 4 is formed of a support and rhodium which is a noble metal catalyst supported on the support. The second catalyst layer 5 is formed of a support and palladium or platinum which is a noble metal catalyst supported on the support. The first catalyst layer 4 is formed in a range of 80% to 100% of a total length of the substrate 1 starting from an end of the substrate on the upstream side, and the second catalyst layer 15 5 is formed in a range of 20% to 50% of the total length of the substrate 1 starting from an end of the substrate on the downstream side.

An exhaust gas treatment system for an internal combustion engine includes an exhaust gas pathway configured to receive exhaust gas from the internal combustion engine, a first ammonia injector configured to inject ammonia into the exhaust gas pathway at a first rate, and a first treatment element positioned downstream of the first ammonia injector. A second ammonia injector is positioned downstream of the first treatment element. The second ammonia injector is configured to inject ammonia into the exhaust gas pathway at a second rate. A controller is configured to estimate an amount of particulate present in the exhaust gas and adjust at least one of the first rate or the second rate based on the estimate.

Provided are automotive catalyst composites having a catalytic material on a carrier, wherein the catalytic material comprises at least two layers. The first layer is deposited directly on the carrier and comprises a first palladium component supported on a first refractory metal oxide component, a first oxygen storage component, or a combination thereof. The second layer is deposited on top of the first layer and comprises a rhodium component supported on a second refractory metal oxide component and a second palladium component supported on a second oxygen storage component, a third refractory metal oxide component or a combination thereof. Generally these catalyst composites are used as three-way conversion (TWC) catalysts. Methods of making and using the same are also provided.

A dual-layer catalyst includes a substrate, a first layer disposed on the substrate, and a second layer disposed on the first layer. The first layer includes a first catalyst for storing NO.sub.x when the first catalyst has a temperature below an active temperature of a second catalyst. The first catalyst is to release the stored NO.sub.x when the first catalyst is heated to the active temperature of the second catalyst. The second layer includes the second catalyst for ammonia Selective Catalytic Reduction of the released NO.sub.x. The dual-layer catalyst is to be included in a catalytic converter and a catalyst system for reducing NO.sub.x emissions from a diesel engine, the NO.sub.x emissions including NO.sub.x emitted during a predetermined cold-start time period.

A porous ceramic honeycomb body including a substrate of intersecting porous walls forming axial channels extending from a first end face to a second end face. An active portion of the walls include a zeolite catalyst disposed inside pores thereof and/or is comprised of an extruded zeolite and a three way catalyst (TWC) is disposed on wall surfaces of at least a portion of the active portion.

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 and a second layer.

A catalytic converter includes a substrate (1) and a catalyst layer (3). The catalyst layer includes a bottom catalyst layer (4), a first top catalyst layer (6) and a second top catalyst layer (7). The second top catalyst layer is provided on a downstream side relative to the first top catalyst layer. The first top catalyst layer is made of a ceria-free zirconia composite oxide support and rhodium. The second top catalyst layer is made of a ceria-containing zirconia composite oxide support and rhodium. The first top catalyst layer has a length that is X % of the entire length of the substrate. The second top catalyst layer has a length that is 100?X % of the entire length of the substrate. A ratio of a density of rhodium in the first top catalyst layer to a density of rhodium in the second top catalyst layer is at least 1 and at most 3.

Provided are an exhaust gas purifying catalyst having high catalytic activity enabling combustion of PM at low temperatures and free from any risk of dispersal of metal elements arousing concern about environmental load, an exhaust gas purification device and filter having a high combustion efficiency of PM, and a method for producing the catalyst. An exhaust gas purifying catalyst contains: an oxide containing at least one element (A) selected from alkali metals and alkaline earth metals and at least one element (B) selected from Zr, Si, Al, and Ti; and a cesium salt.

The present invention provides processes for filtering undesired chemicals in streams of contaminated air for supply to confined areas. The processes provide (1) contacting air with a filter comprising by volume from about 5% to about 95% impregnated zirconium hydroxide, from about 5% to about 95% activated impregnated carbon, and optionally, up to about 50% ammonia removal material; and (2) supplying the contacted air to a confined area.

The present invention provides a photocatalytic composition comprising: a photocatalyst; and an adsorbent material.