An object is to provide an exhaust gas purification catalyst for an internal combustion engine that can achieve a higher exhaust gas purification performance and a higher engine output performance. A catalyst layer is disposed in an exhaust gas passage, formed on a surface of the substrate, and includes: a first catalyst layer exposed to an exhaust gas flow; and a second catalyst layer formed between the first catalyst layer and the substrate. A catalyst component supported on the first catalyst layer includes rhodium. A catalyst component supported on the second catalyst layer includes at least one of palladium and platinum. The first catalyst layer is formed such that a density of the rhodium supported thereon decreases in a step-like manner through a plurality of segment zones segmented along an exhaust gas flow direction, and the second catalyst layer is formed such that a density of the palladium or the platinum supported thereon decreases in a step-like manner through a plurality of segment zones segmented along the exhaust gas flow direction.

An exhaust system for an internal combustion engine, the exhaust system comprising, a lean NO.sub.x trap (LNT), a wall flow monolithic substrate having a NO.sub.x storage and reduction zone thereon, the wall flow monolithic substrate having a pre-coated porosity of 40% or greater, the NO.sub.x storage and reduction zone comprising a platinum group metal loaded on a first support, the first support comprising one or more alkaline earth metal compounds, a mixed magnesium/aluminium oxide, cerium oxide, and at least one base metal oxide selected the group consisting of copper oxide, manganese oxide, iron oxide and zinc oxide.

Provided is an electrically heated catalytic converter including at least a conductive substrate and an electrode member that is fixed to the substrate, in which a protective film is formed on a surface of at least a portion of the electrode member. In the electrically heated catalytic converter, at least a portion of the protective film is formed of Al.sub.2O.sub.3, SiO.sub.2, a composite material of Al.sub.2O.sub.3 and SiO.sub.2, or a composite oxide including Al.sub.2O.sub.3, SiO.sub.2, or a composite material of Al.sub.2O.sub.3 and SiO.sub.2 as a major component, the protective film has an amorphous structure or a partially crystalline glass structure having a crystallization rate of 30 vol % or lower with respect to the entire portion of the protective film, and a thickness of the protective film is in a range of 100 nm to 2 μm.

Provided is an exhaust gas purification catalyst in which the performance of a catalyst metal can be brought out properly, the purification catalyst boasting excellent purification performance during warm-up of an internal combustion engine. The exhaust gas purification catalyst 10 is provided with a substrate 1 and a catalyst layer. A leading end section 1a positioned upstream in the direction of exhaust gas flow (arrow) has a portion in which the flow rate of exhaust gas is relatively high and a portion in which the flow rate of exhaust gas is relatively low during warm-up of the internal combustion engine. The catalyst, layer in the portion of relatively high flow rate of exhaust gas has a high density section 6 in which a noble metal, is supported at relatively high density. The high density section 6 is formed to be shorter than the total length of the exhaust gas purification catalyst 10 from the leading end section 1a in the direction of exhaust gas flow.

An exhaust gas purification device of the present invention is provided with: a substrate of wall flow structure having an inlet cell, an outlet cell and a porous partition wall; an upstream catalyst layer, provided inside the partition wall and disposed in an upstream portion of the substrate including an exhaust gas inflow end section; and a downstream catalyst layer, provided inside the partition wall and disposed in a downstream portion of the substrate including an exhaust gas outflow end section. The upstream catalyst layer and the downstream catalyst layer each contain a carrier and at least one noble metal from among Pt, Pd and Rh, supported on the carrier. The noble metal in the upstream catalyst layer and the noble metal in the downstream catalyst layer are different from each other.

A catalysed filter for a positive ignition internal combustion engine comprises a porous filtering substrate having a total substrate length coated with a three-way catalyst washcoat composition comprising at least one precious metal selected from the group consisting of rhodium and one or both of platinum and palladium supported on a high surface area oxide, and an oxygen storage component, which composition being axially shared by a first zone comprising inlet surfaces of a first substrate length<total substrate length and a second zone comprising outlet surfaces of a second substrate length<total substrate length, wherein a sum of the substrate length in the first zone and the substrate length in the second zone≧100% and wherein one or both of the following applies: a washcoat loading in the first zone>second zone; and a total precious metal loading in the first zone>second zone.

[Summary]

[Problem]

The problem addressed by the present invention lies in providing an exhaust gas purification filter which can efficiently treat particulate matter in exhaust gas.

[Solution]

The present invention provides an exhaust gas purification filter including a substrate comprising a plurality of porous partitions, wherein the partitions form an exhaust gas flow path, a porous catalytic layer is provided on the partitions and the catalytic layer having a thickness of 10 μm or greater is provided over at least 20% of the total length of the partitions in the lengthwise direction thereof, and the catalytic layer having a thickness of 10 μm or greater is not present on the partitions 15 mm from an outflow side.

A provision of assemblies and methods for treating an exhaust gas from an internal combustion engine. The treatment method comprises at least two catalyst stages. The exhaust gas is directed to a first stage catalyst. After the first stage catalyst, the exhaust is passed to an inter-catalyst stage comprising an exhaust cooling process and an oxygen enrichment process. Next, the exhaust is passed to a second stage catalyst for reducing carbon monoxide, ammonia and hydrocarbon concentration in the exhaust gas, before exiting via an outlet.

A heater includes: a plate-like first heater substrate; an electrical heating wire that is provided on a first surface of the first heater substrate in a parallel circuit; electrodes that are connected to the electrical heating wire to allow current to flow in the electrical heating wire; and a plate-like cover substrate that covers the first surface of the first heater substrate, the electrical heating wire, and the electrodes with a second surface thereof. The electrical heating wire of the heater generates heat, so that the amount of heat is supplied. A honeycomb structure includes at least one heater that is provided so as to surround an outer wall thereof.

A honeycomb structure includes a honeycomb structure body including porous partition walls defining a plurality of cells serving as fluid passages extending from an inflow end face to an outflow end face. The partition walls have a porosity of 45 to 65%; the open frontal area of the pores having an equivalent circle diameter of 10 μm or more, of the pores open on the surface of each partition wall, is 20 to 50%; the pore density of the pores having an equivalent circle diameter of 10 μm or more is 200 to 1,000 pores/mm.sup.2; the median opening diameter of the pores having an equivalent circle diameter of 10 μm or more is 40 to 60 μm; the circularity of the pores having an equivalent circle diameter of 10 μm or more is 1.8 to 4.0; and the partition walls have a wet area of 16,500 μm.sup.2 or more.