An exhaust component for a motor vehicle with improved corrosion resistance, including an internal volume, an inlet for receiving exhaust gas, and an outlet for expelling exhaust gas. The exhaust component includes at least one wall that is made of a diffusion surface alloyed metal sheet. The diffusion surface alloyed metal sheet comprises a secondary metal that is formed to a primary metal substrate by diffusion. A weld bead is applied to at least one of the edges of the diffusion surface alloyed metal sheet for edge protection or to join the edge of the diffusion surface alloyed metal sheet to another diffusion surface alloyed metal sheet. The weld bead includes a high chromium content filler metal to protect the weld bead and the primary metal substrate at the weld joint from corrosion.

An exhaust gas purification device includes a substrate including an upstream end and a downstream end and having a length Ls; a first containing Pd particles, extending between the upstream end and a first position, and being in contact with the substrate; a second containing Rh particles, extending between the downstream end and a second position, and being in contact with the substrate; and a third catalyst layer containing Rh particles, extending between the upstream end and a third position, and being in contact with at least the first catalyst layer, wherein an average of a Rh particle size distribution is from 1.0 to 2.0 nm, and a standard deviation of the Rh particle size distribution is 0.8 nm or less in each of the second catalyst layer and the third catalyst layer.

This exhaust gas purifying catalyst is provided with a substrate and a catalyst layer formed on a surface of the substrate. The catalyst layer contains zeolite particles that support a metal, and a rare earth element-containing compound that contains a rare earth element. The rare earth element-containing compound is added in such an amount that the molar ratio of the rare earth element relative to Si contained in the zeolite is 0.001 to 0.014 in terms of oxides.

Subject of the invention is an exhaust gas purification system for a gasoline engine, comprising in consecutive order the following devices:

a first three-way-catalyst (TWC1), a gasoline particulate filter (GPF) and a second three-way-catalyst (TWC2),

wherein the oxygen storage capacity (OSC) of the GPF is greater than the OSC of the TWC2, wherein the OSC is determined in mg/l of the volume of the device.

The invention also relates to methods in which the system is used and uses of the system.

A three-way catalyst article, and its use in an exhaust system for compressed natural gas engines, is disclosed. The catalyst article for treating exhaust gas from compressed natural gas (CNG) engine comprising: a substrate comprising an inlet end, an outlet end with an axial length L; a first catalytic region beginning at the outlet end and extending for less than the axial length L, wherein the first catalytic region comprises a first PGM component; and a second catalytic region beginning at the inlet end, wherein the second catalytic region comprises a second PGM component; wherein the first PGM component comprises palladium, platinum, or a combination thereof; and wherein the second PGM component comprises rhodium.

An exhaust gas purification underfloor catalyst characterized in having a catalyst layer having a lower layer and an upper layer, the lower layer containing alumina and CeO.sub.2, the noble metal content of the lower layer being at most 0.5 mass % in relation to the mass of the lower layer, the upper layer containing Rh, alumina, and CeO.sub.2, the amount of noble metals other than Rh contained being 1 mol % or less in relation to the total amount of noble metals contained in the upper layer, the total amount of CeO.sub.2 contained in the lower layer and the upper layer being 14 g/L to 30 g/L, the amount of CeO.sub.2 contained in the upper layer being 7 g/L to 25 g/L, and the amount of CeO.sub.2 contained in the lower layer being 20% or more of the amount of CeO.sub.2 contained in the upper layer.

A three-way catalyst article is provided for the treatment of exhaust gas from a positive ignition engine, the catalyst article comprising: a substrate having a first layer provided thereon, wherein a second layer is provided on the first layer, wherein the first layer comprises a first metal and a first alumina, and wherein the second layer comprises a second metal and a second alumina, wherein either (i) the first metal is Pd and the second metal is Rh; or (ii) the first metal is Rh and the second metal is Pd; and wherein at least one of the first and second aluminas comprises theta alumina.

An exhaust gas purification catalyst device has catalyst coating layers, which extend from the upstream side to the downstream side of the exhaust gas flow. The catalyst coating layers each have at least three zones present in order from the upstream side to the downstream side of the exhaust gas flow, and each of these at least three zones is an oxidation catalyst zone or a reduction catalyst zone. In the uppermost layer of an oxidation catalyst zone, the total number of atoms of platinum and palladium is greater than the number of atoms of rhodium; in the upper most layer of a reduction catalyst zone, the number of atoms of rhodium is greater than the total number of atoms of platinum and palladium. The oxidation catalyst zones and the reduction catalyst zones alternate at least twice in the exhaust gas flow direction.

The invention relates to a three-way catalytic converter, which is suitable, in particular, for the removal of carbon monoxide, hydrocarbons and nitrogen oxides out of the exhaust gas of combustion engines operated with stoichiometric air-fuel mixture. The three-way catalytic converter is characterized in that it has a high oxygen storage capacity after aging and consists of at least two catalytically active layers.

An exhaust gas purification catalyst comprises a substrate; a catalyst layer formed on the substrate and containing at least palladium (Pd) and rhodium (Rh) as a metal functioning as an oxidation and/or reduction catalyst. The catalyst also comprises a carrier that supports the metal, and an OSC material having oxygen storage capacity. The catalyst layer has, when disposed in the exhaust pipe, a front section positioned upstream in an exhaust gas flow direction within the exhaust pipe, and a rear section positioned downstream of the front section in the exhaust gas flow direction. The front section contains palladium (Pd) but does not contain the OSC material, and a proportion, at which the front section is formed from an upstream leading end in the exhaust gas flow direction, is 10% to 40% with respect to 100% of a total length of the substrate.