An exhaust gas purifying catalyst includes: a wall-flow structure substrate including an inlet cell, an outlet cell, and a porous partition; a first catalyst layer formed inside the partition such that a thickness of the first catalyst layer is between 40% and 60%, inclusive, of an overall thickness T.sub.w of the partition; and a second catalyst layer formed inside the partition such that the second catalyst layer extends across an entire region of the partition in a thickness direction thereof.

Described is a method of coating the inside of an exhaust gas purification catalyst filter with a predetermined amount of catalyst slurry while adjusting the distribution of catalyst components in or on a cell wall of the filter. A predetermined amount of catalyst slurry can be injected into an internal channel of a filter to solve conventional problems caused by excess or surplus slurry injection. The predetermined amount of slurry injected into the internal channel of the filter is coated on or in the cell wall, depending on the viscosity and particle size of the slurry. This enables a coating profile in which the slurry distribution at a front portion of the filter and the slurry distribution at a back portion of the filter differ from each other. In addition, the coating profile on the inner surface of the cell wall or in the pores of the cell wall can be adjusted through the subsequent air blowing, so that the back pressure of the filter and the performance of the catalyst filter, such as catalytic activity, can be improved. In addition, the coating length in the filter can be adjusted by controlling the pressure of air during the air blowing.

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.

The invention relates to a particulate filter which comprises a wall flow filter of length L and two 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 surfaces OE and OA, respectively, and wherein the channels E are closed at the second end and the channels A are closed at the first end, and the coatings Y and Z have the same oxygen storage components and the same carrier materials for noble metals. The invention is characterised in that the coating Y is located in the channels E on the surfaces OE and the coating Z is located in the channels Aon the surfaces OA.

An exhaust gas purification catalyst provides excellent removal performance of methane, which is chemically stable. Exhaust gas purification catalyst includes a substrate that divides cells through which an exhaust gas flows and a catalyst layer that is provided on a surface of the substrate. The catalyst layer includes a palladium layer containing palladium that extends from a first end part which is an end part on the side into which an exhaust gas in the cells flows to a second end part which is an end part on the side from which an exhaust gas flows out, a platinum layer containing platinum that extends from the second end part to the first end part, and a rhodium layer containing rhodium that is laminated with both the palladium layer and the platinum layer.

The present invention provides an exhaust purification filter with which pressure loss can be reduced, the filter having high exhaust purification performance and granular-substance-filtering performance. The exhaust purification filter comprises a filter base material having a wall flow structure, and an exhaust purification catalyst supported on a dividing wall of the filter base material, the exhaust purification filter being such that: a median pore diameter (D50) of the filter base material according to a volumetric basis is 15 μm or greater; and the exhaust purification catalyst is unevenly supported on a high-density layer, in which the density of the exhaust purification catalyst is relatively high, and a low-density layer, in which the density of the exhaust purification catalyst is relatively low.

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 surfaces of the partition walls that each face the inflow-side cell and/or 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 from 3 to 10% based on the apparent area of the catalyst portion present on the partition wall.

Zoned diesel oxidation catalysts containing a higher precious metal loading in the inlet zone that the outlet zone and an equal or shorter length inlet zone are described. Emission treatment systems and methods of remediating nitrogen oxides (NOx), particulate matter, and gaseous hydrocarbons using zoned diesel oxidation catalysts are also described.

Disclosed is a NOx-trapping catalyst having a non-platinum-group-metal NOx-trapping layer, which contains a transition metal, particularly manganese, able to maintain NOx-trapping performance while decreasing the amount of expensive platinum-group metal.

The presently claimed invention provides a tri-metallic layered catalytic article comprising: a) a top layer comprising platinum supported on at least one of an oxygen storage component, zirconia component and an alumina component, and rhodium supported on an oxygen storage component; b) a bottom layer comprising a front zone and a rear zone, said front zone comprising palladium supported on an oxygen storage component and an alumina component, and the rear zone comprises platinum supported on at least one of an alumina component, a ceria component, and an oxygen storage component; and c) a substrate, wherein the weight ratio of palladium to platinum is in the range of 1.0:0.4 to 1.0:2.0.