Provided is a system for treating a flowing exhaust gas comprising a lean NOx trap, a catalyzed soot filter, an ammonia or an ammonia precursor metering system for metering ammonia or an ammonia precursor into the flowing exhaust gas; and an SCR catalyst, wherein the SCR catalyst is disposed downstream of the lean NOx trap and comprises copper and/or iron supported on a small pore molecular sieve.

A synthetic aluminosilicate zeolite catalyst containing at least one catalytically active transition metal selected from the group consisting of Cu, Fe, Hf, La, Au, In, V, lanthanides and Group VIII transition metals, which aluminosilicate zeolite is a small pore aluminosilicate zeolite having a maximum ring size of eight tetrahedral atoms, wherein the mean crystallite size of the aluminosilicate zeolite determined by scanning electron microscope is >0.50 micrometer.

The present disclosure relates to a method for forming a catalyst article comprising: (a) forming a slurry having a solids content of up to 50 wt % by mixing together at least the following components a crystalline molecular sieve in an H.sup.+ or NH.sub.4.sup.+ form, an insoluble active metal precursor and an aqueous solvent at a temperature in the range 10 to 35° C.; (b) coating a substrate with the slurry formed in step (a); and (c) calcining the coated substrate formed in step (b) to form a catalyst layer on the substrate. The present disclosure further relates to a catalyst article, particularly a catalyst article which is suitable for use in the selective catalytic reduction of nitrogen oxides, and to an exhaust system.

A process for preparing C.sub.2 to C.sub.5 olefins includes introducing a feed stream comprising hydrogen and at least one carbon-containing component selected from the group consisting of CO, CO.sub.2, and mixtures thereof into a reaction zone. The feed stream is contacted with a hybrid catalyst in the reaction zone, and a product stream is formed that exits the reaction zone and includes C.sub.2 to C.sub.5 olefins. The hybrid catalyst includes a methanol synthesis component and a solid microporous acid component that is selected from molecular sieves having 8-MR access and having a framework type selected from the group consisting of CHA, AEI, AFX, ERI, LTA, UFI, RTH, and combinations thereof. The methanol synthesis component comprises a metal oxide support and a metal catalyst. The metal oxide support includes titania, zirconia, hafnia or mixtures thereof, and the metal catalyst includes zinc.

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.

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.

The present disclosure provides catalyst compositions for NO.sub.x conversion and wall-flow filter substrates comprising such catalyst compositions. Certain catalyst compositions include a zeolite with sufficient Cu exchanged into cation sites thereof to give a Cu/Al ratio of 0.1 to 0.5 and a CuO loading of 1 to 15 wt. %; and a copper trapping component (e.g., alumina) including a plurality of particles having a D.sub.90 particle size of about 0.5 to 20 microns in a concentration of about 1 to 20 wt. %. The zeolite and copper trapping component can be in the same washcoat layer or can be in different washcoat layers (such that the copper trapping component serves as a “pre-coating” on the wall-flow filter substrate).

The invention relates to the use of a catalyst as a passive nitrogen oxide adsorber, which has a carrier substrate, a zeolite, palladium, and platinum, wherein the palladium is provided in a quantity of 0.01 to 10 wt. %, based on the sum of the weights of zeolite, platinum, and palladium and calculated as a palladium metal, and platinum in a quantity of 0.1 to 10 wt. %, based on the weight of the palladium and calculated as a platinum metal. The invention also relates to the use of said catalyst in connection with a SCR catalyst in an exhaust gas system.

The present disclosure provides msect-4 molecular sieves with OFF and ERI topologies, a preparation method therefor, and applications thereof. An eight-membered ring small pore molecular sieve used as a raw material is dispersed in an aqueous phase. Following that, caustic potash, an aluminum source, and an organic structure-directing agent (OSDA) are added. The pH value is then adjusted to be greater than 10, and a silicon source is introduced to attain the desired silicon-aluminum ratio, followed by stirring reaction, aging, crystallization, filtration, washing, ammonia exchange reaction, drying, and calcination. The msect-4 molecular sieves with OFF and ERI topologies, the preparation method therefor, and applications exhibit excellent hydrothermal stability, a plurality of adsorption sites exposed by a regular bone-like structure, and a large specific surface area. Consequently, this molecular sieves find applicability across various technical fields including selective catalytic reduction, passive adsorption, and catalytic cracking, and has broad application prospects.

The present disclosure provides msect-4 molecular sieves with OFF and ERI topologies, a preparation method therefor, and applications thereof. An eight-membered ring small pore molecular sieve used as a raw material is dispersed in an aqueous phase. Following that, caustic potash, an aluminum source, and an organic structure-directing agent (OSDA) are added. The pH value is then adjusted to be greater than 10, and a silicon source is introduced to attain the desired silicon-aluminum ratio, followed by stirring reaction, aging, crystallization, filtration, washing, ammonia exchange reaction, drying, and calcination. The msect-4 molecular sieves with OFF and ERI topologies, the preparation method therefor, and applications exhibit excellent hydrothermal stability, a plurality of adsorption sites exposed by a regular bone-like structure, and a large specific surface area. Consequently, this molecular sieves find applicability across various technical fields including selective catalytic reduction, passive adsorption, and catalytic cracking, and has broad application prospects.