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.

Certain selective catalytic reduction (SCR) articles, systems and methods provide for high NOx conversion while at the same time low N.sub.2O formation. The articles, systems and methods are suitable for instance for the treatment of exhaust gas of diesel engines. Certain articles have zoned coatings disposed thereon, for example, a zoned coating comprising an upstream zone comprising a coating layer comprising a steam-activated iron-containing molecular sieve and a downstream zone comprising a coating layer comprising a high copper-containing molecular sieve.

It is an object to provide a catalyst that can effectively purify exhaust gas, in particular, carbon monoxide (CO) in exhaust gas, emitted from a diesel engine, a production method therefor, and an exhaust gas purification method using the same. A diesel engine exhaust gas purification catalyst for purifying exhaust gas emitted from a diesel engine of the present invention comprises a precious metal and alumina and/or zeolite supported on a three-dimensional structure, and has peaks for not less than three different pore sizes in a pore size distribution measured by the mercury intrusion method, wherein one of the peaks is a peak 2 at a pore size of not less than 0.3 μm and less than 1.0 μm, and the pore volume of the peak 2 being greater than 3.1% of the total pore volume.

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.

An oxidation catalyst for treating an exhaust gas from a diesel engine, which oxidation catalyst comprises: a first washcoat region comprising platinum (Pt), manganese (Mn) and a first support material; a second washcoat region comprising a platinum group metal (PGM) 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.

An exhaust gas purification catalyst for providing removal performance of methane, which is chemically stable 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 of the cells into which an exhaust gas 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 on both the palladium layer and the platinum layer.

A catalyst for adsorbing hydrocarbon includes a first catalyst configured to adsorb short-chain hydrocarbons and including zeolites having a pore size of about 0.30 nm to about 0.44 nm and a second catalyst configured to adsorb a long-chain hydrocarbon and including zeolites ion-exchanged with a transition metal. The catalyst can be coated on a substrate of a hydrocarbon trap.

The present invention relates to a catalyst comprising a carrier substrate of the length L extending between substrate ends a and b and three washcoat zones A, B and C wherein washcoat zone A comprises one or more first platinum group metals and extends starting from substrate end a over a part of the length L, washcoat zone C comprises one or more first platinum group metals and extends starting from substrate end b over a part of the length L, and washcoat zone B comprises the same components as washcoat zone A and in addition, one or more second platinum group metals and extends between washcoat zones A and C, wherein L=L.sub.A+L.sub.B+L.sub.C, wherein L.sub.A is the length of washcoat zone A, L.sub.B is the length of substrate length B and L.sub.C is the length of substrate length C.

The invention relates to a selective ammonia oxidation catalysts comprising a platinum group metal and a support comprising TiO2 doped with 0-10% by weight of SiO.sub.2, WO.sub.3, ZrO.sub.2, Y.sub.2O.sub.3, La.sub.2O.sub.3, or a mixture thereof. The invention further comprises methods for the manufacture of the selective ammonia oxidation catalysts, and integrated catalyst systems comprising the selective ammonia oxidation catalysts for treating an exhaust gas stream.

The present disclosure relates to copper-containing molecular sieve catalysts that are highly suitable for the treatment of exhaust containing NOx pollutants. The copper-containing molecular sieve catalysts contain ion-exchanged copper as Cu.sup.+2 and Cu(OH).sup.+1, and DRIFT spectroscopy of the catalyst exhibits perturbed T-O-T vibrational peaks corresponding to the Cu.sup.+2 and Cu(OH).sup.+1. In spectra taken of the catalytic materials, a ratio of the Cu.sup.+2 to the Cu(OH).sup.+1 peak integration areas preferably can be ≥1. The copper-containing molecular sieve catalysts are aging stable such that the peak integration area percentage of the Cu.sup.+2 peak (area Cu.sup.+2/(area Cu.sup.+2+area Cu(OH).sup.+1)) increases by ≤20% upon aging at 800° C. for 16 hours in the presence of 10% H.sub.2O/air, compared to the fresh state.