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 platinum-group metal concentration (PGM) of the TWC2 is greater than the PGM of the GPF, wherein the PGM is determined in g/ft3 of the volume of the device. Also disclosed are methods in which the system is used and uses of the system.

Disclosed in the present invention is an integrated catalyst system for stoichiometric-burn natural gas vehicles, the catalyst system consisting of a three-way catalyst, a molecular sieve catalyst, and a base body, the three-way catalyst and the molecular sieve catalyst being coated on a surface of the base body. In the integrated three-way catalyst and molecular sieve catalyst system of the present invention, at the same time that pollutants such as CO, HC, and NO.sub.x in the exhaust of stoichiometric-burn natural gas vehicles are processed, the produced byproduct NH.sub.3 can also be processed, and the conversion rates of CO, HC, NO.sub.x, and NH.sub.3 are high.

A catalytic system is provided which comprises a tubular reactor and at least one catalyst particle located within the tubular reactor. The catalyst particles have a particular geometric form which promotes heat transfer with the tubular reactor. Certain specific catalyst particles are also provided.

A catalyst gauze for an ammonia oxidation process is described, containing a first layer of knitted first wire material, whereby said first wire material is made from a platinum-rhodium alloy, characterized in that said first layer contains an activator in the form of a second wire material which is knitted among the first wire material and which is made from un-alloyed platinum.

A three-way catalyst having low NH.sub.3 formation is disclosed. The catalyst includes a carrier and a coating material. The coating material includes a precious metal active component and a catalytic material. The precious metal active component includes a first precious metal active component and a second precious metal active component. The first precious metal active component is a composition containing Ru. The second precious metal active component is a composition containing Pt, Pd and Rh. Alternatively, the second precious metal active component is a composition containing Pd and Rh.

A catalytic reactor constructed of a thermally conductive housing defining a reaction zone having disposed therein: (a) a plurality of catalytic elements, each comprising a porous material having a catalyst supported thereon, and (b) a plurality of heat transfer elements, each comprising a porous, thermally conductive, and essentially catalytically inactive material; wherein the plurality of catalytic elements and the plurality of heat transfer elements are disposed in an alternating configuration within the reaction zone. The catalytic reactor is useful in chemical reactions where heat transfer is a rate limiting step.

Catalyst compositions containing red mud and rhodium are provided. An exemplary catalyst composition includes about 50 wt % to about 99 wt % of a mixed-oxide material including iron oxide, aluminum oxide, and silicon oxide, and about 1 wt % to about 40 wt % of rhodium oxide, calculated as Rh.sub.2O.sub.3.

A supported catalyst particles include oxide carrier particles and noble metal particles supported on the oxide carrier particles, wherein the mass of the noble metal particles is less than or equal to 5 mass % based on the mass of the oxide carrier particles, and the average particle size of the noble metal particles measured by transmission electron microscopy is 1.0-2.0 nm, with the standard deviation σ less than or equal to 0.8 nm.

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 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 supported on a first PGM support material, wherein the first PGM component comprises rhodium (Rh) and platinum (Pt); and wherein Pt and Rh has a weight ratio of at least 1:10.

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 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, wherein the first PGM component comprises Rh and Pt; a second catalytic region comprising a second PGM component, wherein the second PGM component comprises Pd; and wherein the first PGM component has a Pt to Rh ratio of at least 1:20.