The present invention relates to a particulate filter which comprises a wall-flow filter of length L and two different catalytically active coatings Y and Z, wherein the wall flow filter comprises channels E and A that extend in parallel between a first and a second end of the wall-flow filter and are separated by porous walls which form the surfaces O.sub.E and O.sub.A, respectively, and wherein the channels E are closed at the second end and the channels A are closed at the first end. The invention is characterized in that the coating Y is located in the channels E on the surfaces O.sub.E and the coating Z is located in the porous 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 ZrO.sub.2) in the catalyst portions is from 35 mass % to 85 mass %.

A compression ignition internal combustion engine (30) for a heavy-duty diesel vehicle comprising an exhaust system (32) comprising a composite oxidation catalyst (12, 42) and a soot filter substrate (44, 50) disposed downstream from the composite oxidation catalyst comprising: a substrate (5), preferably a honeycomb flow-through substrate monolith, 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 catalyst washcoat zones (1, 2) arranged axially in series on and along the substrate surface, wherein a first catalyst washcoat zone (1) having a length L.sub.1 and comprising a first catalyst washcoat layer (9), wherein L.sub.1<L, is defined at one end by the first substrate end (I) and at a second end by a first end (15) of a second catalyst washcoat zone (2) having a length L.sub.2 and comprising a second catalyst washcoat layer (11), wherein L.sub.2<L, wherein the second catalyst washcoat zone (2) is defined at a second end thereof by the second substrate end (O), and wherein the first substrate end (I) of the composite oxidation catalyst (12, 42) is oriented to an upstream side and wherein the first catalyst washcoat zone (1) comprises a first refractory metal oxide support material and two or more platinum group metal components supported thereon comprising both platinum and palladium at a weight ratio of platinum to palladium of <1; and the second catalyst washcoat zone (2) 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 (I) comprising a particulate metal oxide having a loading of >48.8 g/l (>0.8 g/in.sup.3), 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 greater than a total platinum group metal loading in the second catalyst washcoat zone (2) and wherein the first catalyst washcoat zone (1) comprises one or more first alkaline earth metal components, preferably barium, supported on the first refractory metal oxide support material.

A catalytic article for treating exhaust gas comprising: a first catalytic region beginning at the inlet end and extending for less than the axial length L, wherein the first catalytic region comprises a first palladium component and a first oxygen storage capacity (OSC) material comprising ceria; a second catalytic region beginning at the outlet end and extending for less than the axial length L, wherein the second catalytic region comprises a second palladium component and a second OSC material comprising ceria; a third catalytic region beginning at the outlet end and extending for less than the axial length L, wherein the third catalytic region comprises a third rhodium component and a third OSC material comprising ceria; wherein at least a portion of the first catalytic region is not covered by the second catalytic region and/or the third catalytic region; and wherein (a) the ceria amount in the first catalytic region is less than 50% of the total ceria amount in the first, second, and third catalytic regions; or (b) the ceria loading in the first catalytic region is less than 50% of the sum of the ceria loading in the first, second, and third catalytic regions.

Provided is an exhaust gas purification catalyst capable of reducing a noble metal amount while maintaining a catalyst performance, which comprises a substrate and at least three catalyst coating layers formed on the substrate, the first and third catalyst coating layers contain Pd as a catalyst metal and are formed in a range of a predetermined length from an upstream end surface in an exhaust gas flow direction, and the second catalyst coating layer contains Rh as a catalyst metal and is formed in a range of a predetermined length from a downstream end surface in the exhaust gas flow direction.

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; and a first catalytic region on the substrate; wherein the first catalytic region comprises a first PGM component and a first inorganic oxide, wherein the IR intensity ratio of bridge CO to atop CO on the PGM component is less than 3:1 under standard CO adsorption procedure.

A particulate filter disclosed herein includes a wall-flow structure substrate 10 and a wash coat layer 20 held inside a partition 16 of the substrate 10. The wash coat layer 20 includes an inlet layer 22 formed to have predetermined length L.sub.A and thickness T.sub.A from near an end thereof on an exhaust gas inflow side X1, and an outlet layer 24 formed to have predetermined length L.sub.B and thickness T.sub.B from near an end thereof on an exhaust gas outflow side X2. The inlet layer 22 and the outlet layer 24 partially overlap each other. In the particulate filter disclosed herein, the inlet layer 22 contains a precious metal catalyst, while the outlet layer 24 contains substantially no precious metal catalyst. The length L.sub.A of the inlet layer is 50% or more and 75% or less of a total length L of the partition 16. Thus, the particulate filter is capable of achieving both PM collection performance and pressure-drop reduction performance at high levels.

A catalyst article for treating exhaust gas comprising: a substrate comprising an inlet end, an outlet end with an axial length L; a first catalytic region beginning at the inlet end and extending for less than the axial length L, wherein the first catalytic region comprises a first platinum group metal (PGM) component, a first inorganic oxide, and an optional first oxygen storage capacity (OSC) material; a second catalytic region beginning at the outlet end and extending for less than the axial length L, wherein the second catalytic region comprises a second PGM component, an optional second inorganic oxide, and a second OSC material; and a third catalytic region; wherein the weight ratio of the first inorganic oxide to the optional first OSC material is greater than 1:1.

The disclosure provides a platinum-containing three-way conversion (TWC) catalyst, and a system for treating an exhaust gas stream from a gasoline engine using the TWC catalyst. The system is configured to introduce controlled quantities of hydrogen gas into the exhaust gas stream upstream of the platinum-containing TWC catalyst article during a cold-start period. Further provided are related methods of treating such exhaust streams. Such systems and methods are useful in reducing a level of one or more of hydrocarbons, carbon monoxide, and nitrogen oxide in a gaseous exhaust stream from a gasoline engine.

An exhaust gas purification catalyst including an alkaline-earth metal carried on a porous carrier in a highly dispersed state. The catalyst layer of the exhaust gas purification catalyst has an alkaline-earth metal carrying region including a porous carrier, Pt, and a sulfuric acid salt of at least one alkaline-earth metal carried on the porous carrier, wherein a value of R.sub.Ae/Pt is 0.5 or more, where R.sub.Ae/Pt represents the Pearson's correlation coefficient calculated using α and β in each pixel obtained by, for a cross section of the region, performing the area analysis by FE-EPMA under the conditions of: pixel size 0.34 μm×0.34 μm; and number of measured pixels 256×256; and measuring an intensity (α: cps) of a characteristic X ray of an element (Ae) of the alkaline-earth metal and an intensity (β: cps) of a characteristic X ray of Pt for each pixel.