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.

An oxidation catalyst is described for treating an exhaust gas from a diesel engine, which oxidation catalyst comprises: a substrate; a first washcoat region disposed on the substrate, wherein the first washcoat region comprises a first platinum group metal (PGM) and a first support material; a second washcoat region adjacent to the first washcoat region, wherein the second washcoat region comprises a second platinum group metal (PGM) and a second support material; a third washcoat region disposed on the substrate, wherein the third washcoat region comprises a third platinum group metal (PGM) and a third support material; and wherein either: (i) the third washcoat region is adjacent to the second washcoat region; or (ii) the second washcoat region is disposed or supported on the third washcoat region. Also described are uses and methods involving the oxidation catalyst.

The present disclosure relates to an exhaust gas cleaning catalyst having a substrate and a catalyst coating layer coated on the substrate, in which the catalyst coating layer has an upstream-side coating layer formed from the upstream-side end portion of the exhaust gas cleaning catalyst in an exhaust gas flow direction and a downstream-side coating layer formed from the downstream-side end portion of the exhaust gas cleaning catalyst in the exhaust gas flow direction, when the upstream-side coating layer and the downstream-side coating layer overlap each other, the upstream-side coating layer is disposed on the downstream-side coating layer, and the upstream-side coating layer contains a catalytic metal and a ZrO.sub.2—CeO.sub.2 composite oxide in which Fe forms a solid solution.

The invention relates to a wall-flow filter, to a method for the production and the use of the filter for reducing harmful exhaust gases of an internal combustion engine. The wall-flow filter was produced by exposing the filter at least twice successively to a powder-gas aerosol.

An oxidation catalyst is described for treating an exhaust gas produced by a diesel engine comprising a catalytic region and a substrate, wherein the catalytic region comprises a catalytic material comprising: bismuth (Bi) or an oxide thereof; an alkali metal or an oxide thereof; a platinum group metal (PGM) selected from the group consisting of (i) platinum (Pt), (ii) palladium (Pd) and (iii) platinum (Pt) and palladium (Pd); and a support material comprising a mixed oxide of alumina and silica, a mixed oxide of silica and a refractory oxide, a composite oxide of alumina and silica, a composite oxide of silica and a refractory oxide, alumina doped with a silica or silica doped with a refractory oxide.

An ammonia oxidation catalyst device, including a substrate, a first catalyst coat layer and a second catalyst coat layer, wherein: the first catalyst coat layer includes inorganic oxide particles and a catalytic noble metal supported on the inorganic oxide particles; the second catalyst coat layer includes an NO.sub.x selective reduction catalyst and a proton zeolite H-Zeolite; the first catalyst coat layer is present on the substrate; and the second catalyst coat layer is present on the first catalyst coat layer.

A particulate filter includes a base material having a wall-flow structure including porous partition walls partitioning inlet and outlet cells, and wash-coating layers held inside partition walls. The wash-coating layers include inlet layers each formed from vicinity of an end portion at exhaust gas inflow side to have predetermined length and thickness and outlet layers each formed from vicinity of end portion at exhaust gas outflow side to have a predetermined length and thickness. The inlet and the outlet layers partially overlap with each other. Inlet layers of particulate filter contain substantially no noble metal catalyst, and outlet layers contain noble metal catalyst. Accordingly, PM collection performance can be easily enhanced in inlet region, and high gas distributability (pressure loss suppression performance) can be maintained in outlet region. Accordingly, it is possible to provide particulate filter capable of achieving high levels of PM collection performance and pressure loss suppression performance.

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.

An exhaust gas purifying catalyst (10) according to the present invention is an exhaust gas purifying catalyst including the first catalyst layer (12). The first catalyst layer (12) includes the first section (14) and the second section (15) in the exhaust gas flow direction. The first section (14) is located on the upstream side in the exhaust gas flow direction relative to the second section (15). A catalyst layer (16) contains a catalytically active component including a specific element. The concentration of the specific element in the catalyst layer (12) is higher in the first section (14) than in the second section (15), in terms of mass per unit volume. When the first section is divided in half along the thickness direction of the first catalyst layer (12), the ratio of a1 to a2, a1/a2, is 1.1 or more, where a1 represents the mass of the specific element that is present on the surface side of the catalyst layer (12) and a2 represents the mass of the specific element that is present on the other side than the surface side of the catalyst layer.

An exhaust gas purification catalyst device has catalyst coating layers, which extend from the upstream side to the downstream side of the exhaust gas flow. The catalyst coating layers each have at least three zones present in order from the upstream side to the downstream side of the exhaust gas flow, and each of these at least three zones is an oxidation catalyst zone or a reduction catalyst zone. In the uppermost layer of an oxidation catalyst zone, the total number of atoms of platinum and palladium is greater than the number of atoms of rhodium; in the upper most layer of a reduction catalyst zone, the number of atoms of rhodium is greater than the total number of atoms of platinum and palladium. The oxidation catalyst zones and the reduction catalyst zones alternate at least twice in the exhaust gas flow direction.