The present invention concerns a process for the production of metal doped cerium compositions comprising a cerium oxide and a metal oxide by precipitation. The invention also concerns metal doped cerium compositions providing high crystallites size and exhibiting high thermal stabilities, which may be used as a catalytic support or for polishing applications.

The present invention relates to a particulate filter which comprises a wall flow filter of length L and two different catalytically active coatings Y and Z, wherein the wall flow filter comprises channels E and A that extend in parallel between a first and a second end of the wall flow filter and are separated by porous walls which form the surfaces O.sub.E and O.sub.A, respectively, and wherein the channels E are closed at the second end and the channels A are closed at the first end. The invention is characterized in that the coating Y is located in the channels E on the surfaces O.sub.E and the coating Z is located in the channels A on the surfaces O.sub.A.

The present disclosure describes hybrid binary catalysts (HBCs) that can be used as engine aftertreatment catalyst compositions, specifically 4-way catalyst compositions. The HBCs provide solutions to the challenges facing emissions control. In general, the HBCs include a porous primary catalyst and a secondary catalyst. The secondary catalyst partial coats the surfaces (e.g., the internal porous surface and/or the external surface) of the primary catalyst resulting in a hybridized composition. The synthesis of the HBCs can provide a primary catalyst whose entire surface, or portions thereof, can be coated with the secondary catalyst.

A four-way conversion catalyst for the treatment of an exhaust gas stream of a gasoline engine, the catalyst comprising a porous wall flow filter substrate comprising an inlet end, an outlet end, a substrate axial length extending between the inlet end and the outlet end, and a plurality of passages defined by porous internal walls of the porous wall flow filter substrate, wherein the plurality of passages comprise inlet passages having an open inlet end and a closed outlet end, and outlet passages having a closed inlet end and an open outlet end; wherein in the pores of the porous internal walls and on the surface of the porous internal walls, which surface defines the interface between the porous internal walls and the passages, the catalyst comprises a three-way conversion catalytic coating comprising an oxygen storage compound and a platinum group metal supported on a refractory metal oxide; wherein in the pores of the porous internal walls, the three-way conversion catalytic coating is present as in-wall-coating and on the surface of the porous internal walls, the three-way conversion catalytic coating is present as on-wall-coating; wherein in addition to said three-way conversion catalytic coating, the catalyst comprises no further coating in the pores of the porous internal walls and no further coating on the surface of the porous internal walls.

The present invention relates to an exhaust gas purification apparatus and an exhaust gas purification method using the same. According to a specific embodiment., the exhaust gas purification apparatus comprises: a diesel oxidation catalyst (DOC) unit for convening nitrogen oxides (NO.sub.8), contained in an exhaust gas introduced therein through a gas inlet portion, into nitrogen dioxide (NO.sub.2); a composite diesel particulate filter (DPF) unit connected to the rear end of the DOC unit through an inflow line and removing harmful components including particulate substances and nitrogen oxides from the exhaust gas discharged from the DOC unit and introduced therein; and a circulation line disposed in the inflow line so as to introduce the exhaust gas discharged from the DOC unit into the gas inlet portion.

A novel exhaust gas purifying catalyst, method for producing same, and an exhaust gas purification device using same, which are capable of maintaining catalytic activity of a precious metal at a higher level than compared with conventional exhaust gas purifying catalysts. An exhaust gas purifying catalyst having a first carrier particle, a second carrier particle, and a precious metal catalyst particle carried on the first and second carrier particles, wherein: the first carrier particle contains a rare-earth oxide other than ceria and at least one metal oxide selected from the group consisting of silica, alumina, ceria, zirconia, and titania; the second carrier particle contains a rare-earth oxide other than ceria; and the contained amount of the rare-earth oxide in the second carrier particle is higher than the contained amount of the rare-earth oxide in the first carrier particle.

An exhaust gas purification device has a metal substrate and a catalyst layer on the metal substrate, wherein the metal substrate is a wound body of one or a plurality of metal foils, at least one of the one or a plurality of metal foils is a perforated metal foil having holes, the catalyst layer contains noble metal catalyst particles and a carrier for carrying the noble metal catalyst particles, and more noble metal catalyst particles are present in the catalyst layer on side surfaces of holes, which face an upstream side of an exhaust gas flow, than in the catalyst layer on side surfaces of holes, which face a downstream side of the exhaust gas flow.

The present disclosure generally provides catalyst compositions, articles and methods for reducing levels of HC, CO and NO.sub.x in an exhaust gas stream using the catalyst compositions and catalytic articles. The compositions, which are doped with niobium oxide, significantly improve the performance of a three-way catalyst when used as the rhodium support while strictly controlling the amount of precious metal loading.

An exhaust system for a diesel engine comprises an oxidation catalyst for treating an exhaust gas from the diesel engine and an emissions control device, wherein the oxidation catalyst comprises: a first washcoat zone for oxidizing carbon monoxide (CO) and hydrocarbons (HCs), wherein the first washcoat zone comprises a first platinum group metal (PGM), which is a combination of platinum and palladium, a first support material and a hydrocarbon adsorbent material, which is a zeolite, and wherein the first washcoat zone does not comprise rhodium and is substantially free of manganese or an oxide thereof; a second washcoat zone for oxidizing nitric oxide (NO), wherein the second washcoat zone comprises platinum (Pt) and manganese (Mn) disposed or supported on a second support material, wherein the second support material comprises a refractory metal oxide, wherein the refractory metal oxide is silica-alumina or an alumina doped with silica in a total amount of 0.5 to 45% by weight of the alumina, and wherein the second washcoat zone does not comprise a hydrocarbon adsorbent material, which is a zeolite; and a substrate having and inlet end and an outlet end, and wherein the second washcoat zone is disposed at an outlet end of the substrate, and the first washcoat zone disposed at an inlet end of the substrate; and wherein the emissions control device is a selective catalytic reduction (SCR) catalyst, a selective catalytic reduction filter catalyst, a diesel particulate filter (DPF), or a catalyzed soot filter (CSF).

An apparatus for purifying exhaust gas includes: an engine; an exhaust gas air-fuel ratio adjustor for adjusting an air-fuel ratio of the exhaust gas; a lean NO.sub.x trap (LNT) mounted on the exhaust pipe and generating ammonia or reducing nitrogen oxides or desorbed nitrogen oxides contained in the exhaust gas using a reducing agent including carbon monoxide, hydrocarbon, or hydrogen contained in the exhaust gas; a three way catalyst (TWC) mounted on the exhaust pipe at a rear end of the LNT, and converting noxious gas in the exhaust gas into harmless components through a redox reaction; and a controller controlling the air-fuel ratio of the exhaust gas to a stoichiometric air-fuel ratio when the nitrogen oxide storage or purification performance of the LNT is in the operating period of the engine less than a predetermined level.