Provided through the present disclosure is a method for reducing nitrogen dioxide in exhaust gas of a stationary source by using selective catalytic reduction (SCR) without injection of a reducing agent, the method comprising the steps of: (a) providing exhaust gas generated in the stationary source wherein the exhaust gas includes at least one of CO, H.sub.2, and hydrocarbon; (b) contacting the exhaust gas with a catalyst to reduce nitrogen dioxide in the exhaust gas; and (c) discharging into air the exhaust gas that has undergone step (b).

The present invention relates to a titania-based selective catalytic reduction (SCR) catalyst article which shows comparable or better performance to those which contain vanadium. In particular, the invention relates to the provision of a titania-based SCR catalyst article comprising ceria and niobia and to methods of making these catalysts.

A three-way catalyst article, and its use in an exhaust system for internal combustion engines, is disclosed. The catalyst article for treating exhaust gas comprising: a substrate comprising an inlet end and an outlet end with an axial length L; a first catalytic region comprising a first platinum group metal (PGM) component supported on a first PGM support material, wherein the first PGM component comprises platinum and rhodium; and wherein the first PGM support material comprises ZrO.sub.2—Al.sub.2O.sub.3.

An aftertreatment system for a diesel engine may include a diesel particulate filter configured for placement in fluid communication with the diesel engine to receive an exhaust flow. The system may also include a selective catalytic reduction system configured for arrangement downstream of the diesel particulate filter and a NO.sub.x sensor configured to measure a NO.sub.x concentration in the exhaust flow entering the selective catalytic reduction system. The system may also include a controller configured to estimate a ratio of NO.sub.2 to NO.sub.x downstream of the diesel particulate filter and based on a factor affecting the generation of NO.sub.2 upstream of the selective catalytic reduction system. The controller may also be configured to adjust the measured NO.sub.x concentration based on the ratio to provide an estimated actual NO.sub.x concentration and dose diesel exhaust fuel into the exhaust flow based on the estimated actual NO.sub.x concentration.

The present disclosure recognizes a correlation between zeolitic surface area (ZSA) of a catalyst composition and its catalytic activity. Particularly, the disclosure provides catalyst articles for diesel NO.sub.x abatement, including a substrate and a washcoat layer containing metal-promoted molecular sieves, wherein the zeolitic surface area (ZSA) of the catalyst article is about 100 m.sup.2/g or greater, the volumetric surface area is about 900 m.sup.2/in.sup.3 or greater, and/or the total zeolitic surface area (tZSA) is about 1200 m.sup.2 or greater. The disclosure further relates to methods for evaluating ZSA, volumetric ZSA, and tZSA, e.g., including the steps of coating a catalyst composition comprising metal-promoted molecular sieves onto a substrate; calcining and aging the catalyst composition; determining the ZSA (or volumetric ZSA or tZSA) thereof; and correlating the ZSA (or volumetric ZSA or tZSA) with catalyst composition NO.sub.x abatement activity to determine whether the catalyst composition is suitable for an intended use.

An oxidation catalyst composite, methods, and systems for the treatment of exhaust gas emissions from a diesel engine are described. More particularly, an oxidation catalyst composite including a first washcoat layer comprising a Pt component and a Pd component, and a second washcoat layer including a refractory metal oxide support containing manganese, a zeolite, and a platinum component is described.

The present disclosure generally provides catalysts, catalytic articles and catalyst systems including such catalytic articles. In particular, the catalyst composition includes a zeolite having a chabazite (CHA) crystal structure ion-exchanged with iron and copper. Methods of making and using the catalyst composition are also provided, as well as emission treatment systems containing a catalyst article coated with the catalyst composition. The catalyst article present in such emission treatment systems is useful to catalyze the reduction of nitrogen oxides in gas exhaust in the presence of a reductant.

The exhaust gas purification catalyst disclosed here is an exhaust gas purification catalyst disposed in the exhaust pipe of an internal combustion engine to purify nitrogen oxides contained in exhaust gas discharged from the internal combustion engine, provided with a silver alumina catalyst comprising at least alumina as a catalyst and silver supported on this alumina, wherein, in the silver alumina catalyst, the ratio of the peak intensity at a wave number of 1595 cm.sup.−1 to the peak intensity at a wave number of 1613 cm.sup.−1 by the pyridine IR method is at least 0.3, and the carried amount of the silver is 1.0 wt % to 6.0 wt % given 100 wt % as the total amount of the silver alumina catalyst.

A mixer for an exhaust system of an internal combustion engine includes a mixer housing (40) with an inflow opening central axis (LE) and with an outflow opening (38). A first flow duct (48) following the inflow opening (24) in the mixer housing (40) and a second flow duct (50) lead parallel to one another to a third flow duct (54) and open into same. The third flow duct (54) leads to the outflow opening (38). The first flow duct (48) and the second flow duct (50) are provided between an outer wall (16) of the mixer housing (40) and a flow divider wall (36) enclosed by the outer wall (16), and the third flow duct (54) is enclosed by the flow divider wall (36).

A CON zeolite satisfying the following (1) to (2): (1) The framework is CON as per the code specified by the International Zeolite Association (IZA); and (2) It contains silicon and aluminum, and the molar ratio of aluminum to silicon is 0.04 or more.