A honeycomb structure has grooves dented inwardly from the surfaces of the partition walls along a cell direction An open width of an open end of the groove is 0.015-0.505 mm and smaller than the open width a length of one side of each of the cells with the grooves, a bottom width of a bottom of the groove is 0.01-0.5 mm and smaller than the open width, a height from the bottom of the groove to the open end is 0.01-0.05 mm, a thickness of the partition wall in a groove portion is 50 m or more, a ratio of the number of the cells with the grooves to the number of the total cells is 80% or more, and a value obtained by subtracting the open frontal area when the grooves excluded from the open frontal area when the grooves included is 0.1-8.0%.

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 oxidation catalyst composite, methods, and systems for the treatment of exhaust gas emissions from a diesel engine are described. More particularly, described is an oxidation catalyst composite including a first oxidation component comprising a first refractory metal oxide support, palladium (Pd) and platinum (Pt); a NO.sub.x storage component comprising one or more of alumina, silica, titania, ceria, or manganese; and a second oxidation component comprising a second refractory metal oxide, a zeolite, and Pt. The oxidation catalyst composite is sulfur tolerant, adsorbs NO.sub.x and thermally releases the stored NO.sub.x at temperature less than 350 C.

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.

Shaped porous carbon products and processes for preparing these products are provided. The shaped porous carbon products can be used, for example, as catalyst supports and adsorbents. Catalyst compositions including these shaped porous carbon products, processes of preparing the catalyst compositions, and various processes of using the shaped porous carbon products and catalyst compositions are also provided.

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 exhaust gas control system includes an upstream purification device disposed in an exhaust passage of the internal combustion engine, a downstream purification device disposed in a portion of the exhaust passage downstream from the upstream purification device, a fuel addition valve disposed in a portion of the exhaust passage upstream from the upstream purification device, and a urea addition valve disposed in a portion of the exhaust passage between the upstream purification device and the downstream purification device, and a cooling device. The cooling device is configured such that refrigerant cools the fuel addition valve first and then cools the urea addition valve subsequent to the fuel addition valve.

A porous material having a hierarchical pore structure, wherein a size and shape of interconnection parts of at least one level pore cavities is consistent with a size and shape of interconnection parts between the level pore cavities and the previous level pore cavities thereof, and an average value of equivalent diameters of the interconnection parts is larger than 45% of that of a diameter of small pore cavities of two adjacent pore cavities of the interconnection parts. The method for preparing the porous material includes: mixing a raw material powder with a pore-forming agent used for preparing the smallest level pores to formulate a slurry; uniformly filling the slurry into a polymeric material frame, and drying and crushing to form mixed grains; then uniformly mixing the mixed grains with the pore-forming agent used for preparing the upper-level pore cavities, forming a compact green body and sintering.

A diesel oxidation catalyst composition is provided, the composition including at least one platinum group metal impregnated onto a porous refractory oxide material in particulate form and at least one base metal oxide impregnated onto a porous refractory oxide material in particulate form, wherein the porous refractory oxide material impregnated with at least one platinum group metal and the porous refractory oxide material impregnated with at least one base metal oxide are in the form of a mixture or wherein the at least one platinum group metal and the at least one base metal oxide are impregnated on the same porous refractory oxide material. The diesel oxidation catalyst provides synergistic enhancement of carbon monoxide oxidation as well as relatively unimpaired hydrocarbon oxidation. Methods of making and using the catalyst composition are also provided, as well as emission treatment systems comprising a catalyst article coated with the catalyst composition.