A method of selectively catalysing the reduction of oxides of nitrogen (NO.sub.x) including nitrogen monoxide in an exhaust gas of a stationary source of NO.sub.x emissions also containing oxides of sulfur (SO.sub.x) comprising the steps of passively oxidising nitrogen monoxide to nitrogen dioxide (NO.sub.2) over an oxidation catalyst comprising a platinum group metal so that a NO.sub.2/NO.sub.x content is from 40-60%; introducing a nitrogenous reductant into the exhaust gas; and contacting exhaust gas having the 40-60% NO.sub.2/NO.sub.x content and containing the nitrogenous reductant with a selective catalytic reduction (SCR) catalyst comprising an aluminosilicate zeolite promoted with copper.

An exhaust system for treating an exhaust gas from an internal combustion engine is disclosed. The system comprises a modified lean NO.sub.x trap (LNT), a urea injection system, and an ammonia-selective catalytic reduction catalyst. The modified LNT comprises a first layer and a second layer. The first layer comprises a NO.sub.x adsorbent component and one or more platinum group metals. The second layer comprises a diesel oxidation catalyst zone and an NO oxidation zone. The diesel oxidation catalyst zone comprises a platinum group metal, a zeolite, and optionally an alkaline earth metal. The NO oxidation zone comprises a platinum group metal and a carrier. The modified LNT stores NO.sub.x at temperatures below about 200° C. and releases at temperatures above about 200° C. The modified LNT and a method of using the modified LNT are also disclosed.

An exhaust system for treating an exhaust gas from an internal combustion engine is disclosed. The system comprises a modified lean NO.sub.x trap (LNT), a urea injection system, and an ammonia-selective catalytic reduction catalyst. The modified LNT comprises a first layer and a second layer. The first layer comprises a NO.sub.x adsorbent component and one or more platinum group metals. The second layer comprises a diesel oxidation catalyst zone and an NO oxidation zone. The diesel oxidation catalyst zone comprises a platinum group metal, a zeolite, and optionally an alkaline earth metal. The NO oxidation zone comprises a platinum group metal and a carrier. The modified LNT stores NO.sub.x at temperatures below about 200° C. and releases at temperatures above about 200° C. The modified LNT and a method of using the modified LNT are also disclosed.

An exhaust gas purification device includes a substrate including an upstream end and a downstream end and having a length Ls; a first containing Pd particles, extending between the upstream end and a first position, and being in contact with the substrate; a second containing Rh particles, extending between the downstream end and a second position, and being in contact with the substrate; and a third catalyst layer containing Rh particles, extending between the upstream end and a third position, and being in contact with at least the first catalyst layer, wherein an average of a Rh particle size distribution is from 1.0 to 2.0 nm, and a standard deviation of the Rh particle size distribution is 0.8 nm or less in each of the second catalyst layer and the third catalyst layer.

Catalyst for hydrogenation of 1,3-cyclobutanediketone compound is provided, which includes a support and VIIIB group transition metal loaded thereon. The support includes a first oxide powder with a surface wrapped by a second oxide. The first oxide includes silicon oxide, aluminum oxide, zirconium oxide, titanium oxide, zinc oxide, or a combination thereof. The second oxide has a composition of M.sub.xAl.sub.(1-x)O.sub.(3-x)/2, M is alkaline earth metal, and x is from 0.3 to 0.7.

The present disclosure provides a monolith substrate used for an exhaust gas purifying catalyst that improves purification performance, a method for producing such monolith substrate, and an exhaust gas purifying catalyst comprising such monolith substrate. The present disclosure relates to a monolith substrate comprising an alumina-ceria-zirconia composite oxide and alumina, a method for producing such monolith substrate, and an exhaust gas purifying catalyst comprising such monolith substrate.

An object of at least one embodiment of the present invention is to suppress poisoning due to phosphorus derived from engine oil, and effectively purify NOx discharged from the time of engine start up to a high load condition. In an exhaust gas purification catalyst for an internal combustion engine, a catalyst layer includes: a first catalyst layer exposed to an exhaust gas flow; and a second catalyst layer formed between the first catalyst layer and the substrate. A second catalyst upstream layer formed on an upstream side of the second catalyst layer with respect to the exhaust gas flow and a first catalyst downstream layer formed on a downstream side of the first catalyst layer with respect to the exhaust gas flow include at least one of palladium and platinum, as well as an oxygen storage material as the catalyst component. An amount of the oxygen storage material in the first catalyst downstream layer is larger than an amount of the oxygen storage material in the second catalyst upstream layer.

An object is to provide an exhaust gas purification catalyst for an internal combustion engine that can achieve a higher exhaust gas purification performance and a higher engine output performance. A catalyst layer is disposed in an exhaust gas passage, formed on a surface of the substrate, and includes: a first catalyst layer exposed to an exhaust gas flow; and a second catalyst layer formed between the first catalyst layer and the substrate. A catalyst component supported on the first catalyst layer includes rhodium. A catalyst component supported on the second catalyst layer includes at least one of palladium and platinum. The first catalyst layer is formed such that a density of the rhodium supported thereon decreases in a step-like manner through a plurality of segment zones segmented along an exhaust gas flow direction, and the second catalyst layer is formed such that a density of the palladium or the platinum supported thereon decreases in a step-like manner through a plurality of segment zones segmented along the exhaust gas flow direction.

An exhaust system for an internal combustion engine, the exhaust system comprising, a lean NO.sub.x trap (LNT), a wall flow monolithic substrate having a NO.sub.x storage and reduction zone thereon, the wall flow monolithic substrate having a pre-coated porosity of 40% or greater, the NO.sub.x storage and reduction zone comprising a platinum group metal loaded on a first support, the first support comprising one or more alkaline earth metal compounds, a mixed magnesium/aluminium oxide, cerium oxide, and at least one base metal oxide selected the group consisting of copper oxide, manganese oxide, iron oxide and zinc oxide.

Phosphorus tolerant or resistant three-way catalysts (TWC) are disclosed. The TWC may include a substrate defining a plurality of channels. It may include front and rear washcoat portions overlying the substrate and having respective first and second washcoat loadings, the first washcoat loading being at most 2.0 g/in.sup.3 and less than the second washcoat loading. The front washcoat portion may include a catalyst material supported on a support material comprising a cerium oxide, such as ceria or CZO, or a pre-phosphated material, such as AlPO.sub.4, or CePO.sub.4. In one embodiment, the support material may comprise at least 85 wt. % of a cerium oxide or at least 85 wt. % of a phosphate-containing material. The front portion and the underlying substrate may comprise from 3 to 25 vol. % of the three-way catalyst or the front portion may overly up to an initial 15% of an axial length of the substrate.