SCR-active molecular-sieve based catalysts with improved low-temperature performance are made by heating a molecular-sieve in a non-oxidizing atmosphere with steam (hydrothermal treatment), or in a reducing atmosphere without steam (thermal treatment), at a temperature in the range of 600-900° C. for a time period from 5 minutes to two hours. The resulting SCR-active iron-containing molecular sieves exhibit a selective catalytic reduction of nitrogen oxides with NH.sub.3 or urea at 250° C. that is at least 50% greater than if the iron-containing molecular-sieve were calcined at 500° C. for two hours without performing the hydrothermal or thermal treatment.

The present invention is directed towards the use of an ion-exchanged zeolite containing ASC as a trap for volatile vanadium compounds in a downstream position of a vanadium containing SCR-catalyst.

The invention provides an emission control system for treatment of an exhaust gas stream that includes an oxidation catalyst composition disposed on a substrate in fluid communication with the exhaust gas stream; at least one selective catalytic reduction (SCR) composition disposed on a substrate downstream from the oxidation catalyst composition, and a hydrogen injection article configured to introduce hydrogen into the exhaust gas stream upstream of the oxidation catalyst composition or downstream of the oxidation catalyst composition and upstream of the at least one SCR composition. The invention also provides a method of treating an exhaust gas stream, the method including receiving the exhaust gas stream into the emission control system of the invention and intermittently introducing hydrogen upstream of the oxidation catalyst article or downstream of the oxidation catalyst article and upstream stream of the SCR article.

The invention relates to a particle filter, which comprises a wall flow filter and SCR-active material, wherein the wall flow filter comprises ducts which extend in parallel between the first and the second end of the wall flow filter and which are alternately closed in a gas-tight manner either at the first or the second end and which are separated by porous walls, the pores of which have inner surfaces, and the SCR-active material is located in the form of a coating on the inner surfaces of the pores of the porous walls, characterized in that the coating has a gradient, such that the side of the coating facing the exhaust gas has a higher selectivity in the SCR reaction than the side of the coating that faces the inner surfaces of the pores. The SCR-active material is preferably a small-pore zeolite, which has a maximum ring size of eight tetrahedral atoms and is exchanged with copper and/or iron.

The present invention provides hydrothermally stable crystalline aluminosilicate zeolites with a CHA framework type, wherein the zeolite has a total proton content of less than 2 mmol per gram. The zeolite may comprise 0.1 to 10 wt.-% of at least one transition metal, calculated as the respective oxide and based on the total weight of the zeolite. It may furthermore comprise at least one alkali or alkaline earth metal in a concentration of 0 to 2 wt.-%, calculated as the respective metal and based on the total weight of the zeolite. The invention furthermore provides a one-pot synthesis method for making the alumino-silicate zeolites with a CHA framework type. An aqueous reaction mixture comprising a tetraethylammonium compound, a silica source, at least one alkali or alkaline earth metal hydroxide, a zeolite of the faujasite framework type and Cu-tetraethylenepentamine are mixed, homogenized and heated, and finally, the product is recovered. The novel hydrothermally stable zeolites comprising a CHA framework type are suitable as catalytically active materials for the selective catalytic reduction of nitrogen oxides by reaction with NH.sub.3 as reductant (NH.sub.3-SCR) wherein said hydrothermally stable zeolites are used.

The present invention relates to a method for preventing an SCR catalyst from being contaminated with platinum group metal in an emission control system comprising, upstream of the SCR catalyst, a catalyst that contains platinum group metal, characterized in that a material zone containing a mixture of aluminum oxide and cerium oxide is located upstream of the SCR catalyst.

A catalyst includes LTA zeolite including copper ions, wherein a Si/Al ratio of the LTA zeolite is 2 to 50. The catalyst is coated on a honeycomb carrier or a filter. The catalyst removes NOx from a reaction gas at 100° C. or above. The catalyst has an NOx conversion rate of 80% at 450° C. or above.

Provided are novel synthesis techniques for producing pure phase aluminosilicate zeolite and a catalyst comprising the phase pure zeolite in combination with a metal, and methods of using the same.

A process for preparing a porous oxidic material with micropores and mesopores and a zeolitic material having an AEI framework with a tetravalent element Y, a trivalent element X and oxygen, the micropores having a pore diameter determined by nitrogen adsorption-desorption at 77 K of less than 2 nm and the mesopores having a pore diameter of from 2 to 50 nm, the process involving subjecting a synthesis mixture to hydrothermal crystallization at a crystallization temperature of from 90 to 200° C., to obtain a mother liquor containing the porous oxidic material having the zeolitic AEI framework. The synthesis mixture may have a zeolitic material with an FAU framework comprising Y, X, and O, water, a base source, a first organic structure directing agent as an AEI framework type structure directing agent, a second organic structure directing agent with a dimethyl-octadecyl[3-(trimethoxysilyl)-propyl]ammonium cation, and seed crystals

A catalytic article for treating an exhaust gas stream containing particulate matter, hydrocarbons, CO, and ammonia, the article may include: (a) a substrate having an inlet end and an outlet end defining an axial length; (b) a first catalyst coating including: 1) a platinum group metal distributed on a molecular sieve, and 2) a base metal distributed on a molecular sieve; and (c) a second catalyst coating including: 1) a platinum group metal distributed on a molecular sieve, and 2) a base metal distributed on a molecular sieve.