The present disclosure provides SCR catalyst compositions capable of reducing nitrogen oxide (NO.sub.x) emissions in engine exhaust. The catalyst compositions include a reducible metal oxide support containing ceria, one or more transition metal oxides as a redox promotor; and an oxide of niobium, tungsten, silicon, molybdenum, or a combination thereof as an acidic promotor. The redox promotor and the acid promotor are both supported on the reducible metal oxide support. Further provided are SCR catalyst articles coated with such compositions, processes for preparing such catalyst compositions and articles, an exhaust gas treatment system including such catalyst articles, and methods for reducing NO.sub.x in an exhaust gas stream using such catalyst articles and systems.

A composite, zone-coated, dual-use ammonia (AMOX) and nitric oxide oxidation catalyst (12) comprises: a substrate (5) having a total length L and a longitudinal axis and having a substrate surface extending axially between a first substrate end (I) and a second substrate end (O); two or more catalyst washcoat zones (1; 2) comprised of a first catalyst washcoat layer (9) comprising a refractory metal oxide support material and one or more platinum group metal components supported thereon and a second catalyst washcoat layer (11) different from the first catalyst washcoat layer (9) and comprising a refractory metal oxide support material and one or more platinum group metal components supported thereon, which two or more catalyst washcoat zones (1; 2) being arranged axially in series on and along the substrate surface, wherein a first catalyst washcoat zone (1) having a length L.sub.1, wherein L.sub.1<L, is defined at one end by the first substrate end (I) and at a second end (13) by a first end (15) of a second catalyst washcoat zone (2) having a length L.sub.2, wherein L.sub.2<L, wherein the first catalyst washcoat zone (1) comprises a first refractory metal oxide support material and one or more platinum group metal components supported thereon; and the second catalyst washcoat zone comprises a second refractory metal oxide support material and one or more platinum group metal components supported thereon; and a washcoat overlayer (G) extending axially from the first substrate end for up to 200% of the axial length of the underlying first catalyst washcoat layer, which washcoat overlayer comprising a particulate metal oxide loading of >48.8 g/l (>0.8 g/in.sup.3), wherein the particulate metal oxide is an aluminosilicate zeolite including at least one of copper, iron and manganese, wherein a total platinum group metal loading in the first catalyst washcoat zone (1) defined in grams of platinum group metal per litre of substrate volume (g/l) is different from the total platinum group metal loading in the second catalyst washcoat zone (2).

A selective catalytic reduction catalyst for the treatment of an exhaust gas stream of a passive ignition engine, the catalyst comprising a porous wall-flow filter substrate comprising an inlet end, an outlet end, a substrate axial length (w) extending between the inlet end and the outlet end, and a plurality of passages defined by porous internal walls of the porous wall flow filter substrate; wherein the catalyst further comprises a first coating, said first coating extending over x % of the substrate axial length from the inlet end toward the outlet end of the substrate, x being in the range of from 10 to 100, wherein the first coating comprises copper and an 8-membered ring pore zeolitic material; wherein the catalyst further comprises a second coating, the second coating extending over y % of the substrate axial length from the outlet end toward the inlet end of the substrate, y being in the range of from 20 to 90, wherein the second coating comprises copper, and optionally an 8-membered ring pore zeolitic material; wherein the catalyst optionally further comprises a third coating; wherein x+y is at least 90; wherein y % of w from the outlet end toward the inlet end of the substrate define the outlet zone of the coated substrate and (100−y) % of w from the inlet end toward the outlet end of the substrate define the inlet zone of the coated substrate; wherein the ratio of the loading of copper in the inlet zone, Cu(in), calculated as CuO, relative to the loading of copper in the outlet zone, Cu(out), calculated as CuO, Cu(in):Cu(out), is less than 1:1.

An exhaust gas purification catalyst apparatus has a honeycomb base material and a catalyst noble metal supported by the honeycomb base material, wherein: the honeycomb base material contains ceria-zirconia composite oxide particles as one of the constituent materials, is of a wall flow type, and includes inlet-side cells and outlet-side cells demarcated by porous partition walls; the catalyst noble metal is supported in inlet-side support regions and outlet-side support regions; each of the inlet-side support regions is formed with a specific length from the exhaust gas flow upstream end; the catalyst noble metal 70% support depth is not greater than 50% of the thickness of the porous partition walls; each of the outlet-side support regions is formed with a specific length from the exhaust gas flow downstream end; and the catalyst noble metal 70% support depth is greater than 50% of the thickness of the porous partition walls.

A substrate (11) of an exhaust gas purification catalyst (10) includes inflow-side cells (21), outflow-side cells (22), and porous partition walls (23), each separating the inflow-side cell and the outflow-side cell. Catalyst portions (14, 15) are provided on the surfaces of the partition walls that each face the inflow-side cell and/or the surfaces of the partition walls that each face the outflow-side cell. In a cross section vertical to an exhaust gas flow direction, the percentage of the total area of voids, each void satisfying the expression L/{2(πS).sup.1/2}≤1.1 (wherein L is the perimeter of the void in the cross section, and S is the area of the void in the cross section), is greater than 10% to 30% or less based on the apparent area of the catalyst portion present on the partition wall. The content of zirconium element in terms of oxide (amount of ZrO2) in the catalyst portions is from 35 mass % to 85 mass %.

There is provided an exhaust gas purification device that shows a high HC removal performance under a condition in which a rich air-fuel mixture is introduced. The exhaust gas purification device includes a substrate, a first catalyst layer, and a second catalyst layer. The substrate includes an upstream end and a downstream end. The first catalyst layer is disposed on a surface of the partition wall in an upstream region including the upstream end of the substrate. The second catalyst layer is disposed inside the partition wall in a downstream region including the downstream end of the substrate. The first catalyst layer contains a first metal catalyst and alumina-zirconia composite oxide. The second catalyst layer contains a second metal catalyst.

The present invention relates to a diesel oxidation catalyst comprising a substrate and a wash-coat comprising a first layer and a second layer, wherein the substrate has a substrate length, a front end and a rear end, the washcoat comprising the first layer comprising a first metal oxide and comprising a platinum group metal supported on a metal oxide support material; the second layer comprising a second metal oxide and comprising one or more of an oxidic compound of vanadium, an oxidic compound of tungsten and a zeolitic material comprising one or more of Fe and Cu; wherein the first layer is at least partially disposed directly on the substrate, or is at least partially disposed directly on an intermediate layer which is disposed directly on the substrate over the entire length of the substrate, on x % of the length of the substrate from the front end of the substrate, and wherein the second layer is at least partially disposed directly on the substrate, or is at least partially disposed directly on the intermediate layer which is disposed directly on the substrate over the entire length of the substrate, on y % of the length of the substrate from the rear end of the substrate, wherein x is in the range of from 25 to 75 and y is in the range of from 25 to 75 and wherein x+y is in the range of from 95 to 105, wherein the intermediate layer comprises alumina.

A filter element for a particle filter having a porous filter body made of a ceramic material and including a plurality of flow channels extending fluidically in parallel. The filter body is provided at least in a part of the flow channels with a coating made of a coating material, which is different from the ceramic material and is made up of orthorhombic crystals. A particle filter, a method for producing a filter element, and the use of a coating material for coating a filter element is also provided.

An automotive catalytic converter includes a three-way catalyst having Rh as the only precious metal configured as a front zone and a three-way catalyst having a mixture of Rh and Pd, Pt, or both configured as a rear zone, such that an exhaust gas from an internal combustion engine passes through the front zone before passing through the rear zone to minimize sulfur poisoning of the catalytic converter.

A catalytic 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 support; a second catalytic region comprising a second PGM component on a support with low ammonia storage and a first SCR catalyst; and wherein the first catalytic region is covered by at least another catalytic region.