An oxidation catalyst is described for treating an exhaust gas produced by a diesel engine. The oxidation catalyst comprises: a substrate; a capture material for capturing at least one sulfur containing impurity in the exhaust gas produced by the diesel engine; wherein the capture material comprises a metal for reacting with an oxide of sulfur in the exhaust gas and particles of a refractory oxide, wherein the particles of the refractory oxide have a mean specific surface area 50 m.sup.2/g; and a catalytic region disposed on the substrate; wherein the catalytic region comprises a catalytic material comprising a platinum group metal (PGM) selected from the group consisting of platinum (Pt), palladium (Pd) and a combination of platinum (Pt) and palladium (Pd).

Catalytic materials, and in particular, rhodium-containing catalytic materials for exhaust gas purifying catalyst composites are provided herein. Such materials comprise multimetallic Rh-containing nanoparticles, which are present primarily inside aggregated particles of a support (such as alumina). Such catalytic materials can exhibit excellent conversion of hydrocarbons and nitrogen oxides.

Catalytic materials for exhaust gas purifying catalyst composites comprise platinum group metal (PGM)-containing catalysts whose PGM component(s) are provided as nanoparticles and are affixed to a refractory metal oxide, which may be provided as a precursor. Upon calcination of the catalysts, the PGM is thermally affixed to and well-dispersed throughout the support. Excellent conversion of hydrocarbons and nitrogen oxides can advantageously be achieved using such catalysts.

An oxidation catalyst for treating an exhaust gas produced by a stoichiometric natural gas (NG) engine comprising a substrate and a catalytic material for oxidising hydrocarbon (HC), wherein the catalytic material for oxidising hydrocarbon (HC) comprises a molecular sieve and a platinum group metal (PGM) supported on the molecular sieve, wherein the molecular sieve has a framework comprising silicon, oxygen and optionally germanium.

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.

An oxidation catalyst for treating an exhaust gas from a diesel engine and an exhaust system comprising the oxidation catalyst are described. The oxidation catalyst comprises: a first washcoat region for oxidizing carbon monoxide (CO) and hydrocarbons (HCs), wherein the first washcoat region comprises a first platinum group metal (PGM) and a first support material; a second washcoat region for oxidizing nitric oxide (NO), wherein the second washcoat region comprises platinum (Pt), manganese (Mn) and a second support material; and a substrate having an inlet end and an outlet end; wherein the second washcoat region is arranged to contact the exhaust gas at the outlet end of the substrate and after contact of the exhaust gas with the first washcoat region.

According to various embodiments, an exhaust treatment system includes a catalyst that is in direct contact with an exhaust stream, at least one sensor that senses a system parameter and produces one or more signals corresponding to the system parameter, and a controller that is configured to receive the one or more signals and control catalyst performance based on the one or more signals by regenerating the catalyst. Regenerating the catalyst includes increasing a temperature of the exhaust stream flowing to the catalyst and directing a reductant injector to adjust a flow rate of reductant being injected into the exhaust stream flowing to the catalyst.

An oxidation catalyst for treating an exhaust gas from a diesel engine, which oxidation catalyst comprises: a first washcoat region comprising a first platinum group metal (PGM), a first support material and a NO.sub.x storage component; a second washcoat region comprising platinum (Pt), manganese (Mn) and a second support material; and a substrate having an inlet end and an outlet end.

Provided is an ammonia slip catalyst article having supported palladium in a top or upstream layer for oxidation of carbon monoxide and/or hydrocarbons, an SCR catalyst either in the top layer or in a separate lower or downstream layer, and an ammonia oxidation catalyst in a bottom layer. Also provided are methods for treating an exhaust gas using the catalyst article, wherein the treatment involves reducing the concentrations of ammonia and optionally carbon monoxide and/or hydrocarbons in the exhaust gas.

An exhaust gas purification catalyst contains an oxide 1 and an oxide 2. The catalyst has pores P.sub.1-260 with a pore size of from 1 nm to 260 nm, that can be measured by the nitrogen absorption method, and the total sum PV.sub.1-260 of the pore volume PV.sub.1-260 of the pores is equal to or greater than 0.79 cm.sup.3/g.

The oxide 1 is an oxide with an oxygen release capability. The oxide 2 is represented by La.sub.xM.sub.1-xMO.sub.3- (2), where M is at least one element selected from the group consisting of Ba, Sr and Ca, M is at least one element selected from the group consisting of Fe, Co, Ni and Mn, is the amount of oxygen deficiency, x satisfies 0x1, and satisfies 01.