A selective catalytic reduction (SCR) catalyst composition effective in the abatement of nitrogen oxides (NO.sub.x) is provided. The SCR catalyst composition significantly increases the conversion of NO.sub.x relative to a Cu-chabazite reference catalyst composition at any temperature, and especially at low temperatures. A catalyst article, an exhaust gas treatment system, and a method of treating an exhaust gas stream, each including the SCR catalyst composition of the invention, are also provided. The SCR catalyst composition is particularly useful for treatment of exhaust from a lean-burn engine.

A novel catalyst constituent material for combustion gas purification, which has an extremely good ratio of contact between each catalyst metal particle and an exhaust gas; and catalyst device which uses this catalyst constituent material for combustion gas purification; and a method for producing this catalyst constituent material for combustion gas purificaton. The catalyst constituent obtained by mixing catalyst metal particles and a pore-forming material that disappears at high temperatures into a catalyst supporting material which is a slurry containing fine ceramic particles. The pore-forming material also contains long fibers of cellulose nanofibers and/or short fibers of cellulose nanofibers.

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 and a first oxygen storage capacity (OSC) material, wherein the first OSC material has a fresh specific surface area (SSA) of at least 10 m.sup.2/g; and wherein the first OSC material has an SSA difference of no more than 30 m.sup.2/g between the fresh first OSC material and the aged first OSC material.

The present disclosure provides an exhaust gas purification catalyst having improved durability, which comprises a substrate and a catalyst coat layer formed on the substrate, the catalyst coat layer having a two-layer structure, wherein the catalyst coat layer includes an upstream portion on an upstream side and a downstream portion on a downstream side in an exhaust gas flow direction, and a part or all of the upstream portion is formed on a part of the downstream portion, wherein the downstream portion contains Rh fine particles, and wherein the Rh fine particles have an average particle size measured by a transmission electron microscope observation of 1.0 nm or more to 2.0 nm or less, and a standard deviation a of the particle size of 0.8 nm or less.

Provided are an LNT layered catalyst for a lean burn gasoline engine having an enhanced NOx storage rate and capable of developing a higher NOx purification rate, and an exhaust gas purification apparatus using the same, the LNT layered catalyst including a substrate, a first catalyst layer including ceria-alumina particles carrying Pt, Pd, and BaO, and a second catalyst layer including ceria-alumina particles carrying Pt and Rh, in which a content of Pt in the first catalyst layer is 0.45 to 0.85 mass %; among Pt included in the first catalyst layer, a content proportion in a first depth region is 88 to 90 mass %, and a content proportion in a second depth region is 10 to 12 mass %; a content of Ba in the first catalyst layer is 4 to 11 mass %; and the second catalyst layer is substantially free from Ba.

A catalyst article including a substrate with an inlet side and an outlet side, a first zone and a second zone, where the first zone includes a passive NOx adsorber (PNA), and an ammonia slip catalyst (ASC) comprising a platinum group metal on a support and a first SCR catalyst; where the second zone includes a catalyst selected from the group consisting of a diesel oxidation catalyst (DOC) and a diesel exotherm catalyst (DEC); and where the first zone is located upstream of the second zone. The first zone may include a bottom layer with a blend of: (1) the platinum group metal on a support and (2) the first SCR catalyst; and a top layer with a second SCR catalyst, the top layer located over the bottom layer.

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.

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, a second layer, and a third layer.

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, an outlet end with an axial length L; an inlet catalyst layer beginning at the inlet end and extending for less than the axial length L, wherein the inlet catalyst layer comprises an inlet palladium component; an outlet catalyst layer beginning at the outlet end and extending for less than the axial length L, wherein the outlet catalyst layer comprises an outlet rhodium component; and wherein the outlet catalyst layer overlaps with the inlet catalyst layer.

The exhaust gas purification catalyst device includes an upper layer which includes first carrier particles and rhodium, and a lower layer which includes second carrier particles, and the upper layer includes a rhodium enriched area in the range a, from the upstream end in the exhaust gas flow to 50% of the upper layer length, and a range b from the upper layer top surface to 18 μm in the depth direction. The rhodium enriched area contains at least 50% and less than 100% of all the rhodium in the upper layer.