A TiO 2 containing catalyst for denitrizing nitrogen oxides in the presence of a hydrocarbon as a reducing agent is disclosed. There are also disclosed denitrizing catalysts which contain zeolite or perovskite structure complex compound.

Catalysts and methods for denitrization

A novel catalyst for use in purification of exhaust gases from diesel engines is disclosed. This catalyst is a flow-through type honeycomb catalyst having parallel through cells and characterized in that (1) its cross-sectional area at the inlet part of an exhaust gas cut by a face vertical to the direction of the through cells is 10 to 100 cm, preferably 20 to 80 cm per liter of the displacement of the engine, (2) the hydraulic diameter of the through cells is 1.00 to 2.00 mm, preferably 1.10 to 1.40 mm, and (3) percentage of open frontal area at the inlet part of the exhaust gas is 40 to 95 % preferably 50 to 85 %. This catalyst can be one wherein a catalytically active component itself is extruded into a honeycomb shape or one wherein a catalytically active component is deposited on a honeycomb carrier.

Catalyst for purification of exhaust gas from diesel engine

A preferred catalytically active solid acid material, zeolite, forms the basis of a washcoat effective for treating diesel-fueled engine exhaust to reduce emission of particulate. In a preferred method, hydrocarbon in exhaust is cracked and oxidized in the presence of a zeolite/silica washcoat mixture catalyzed with precious metal. A preferred Y-type zeolite provides acidic (cationic) sites having releasable cations which are exchanged with precious metal to form catalyzed zeolite. A preferred method of making the catalyzed zeolite/silica washcoat is provided, whereby colloidal silica is disposed as a barrier over the catalyzed washcoat, limiting exposure of catalyst to sulfur constituents in the exhaust.

Catalyst for treatment of diesel exhaust particulate

A method for removing nitrogen oxides from exhaust gases containing oxygen and moisture, which comprises bringing the exhaust gas into contact with hydrogenated zeolite catalysts or hydrogenated zeolite catalysts impregnated with one or more kinds of metals selected from the group consisting of copper, zinc, vanadium, chromium, manganese, iron, cobalt, nickel, rhodium, palladium, platinum, and molybdenum, in the presence of organic compounds. The zeolite should be a zeolite having a silica/alumina ratio of 5 or above. The zeolite may be any one of zeolite of Y type, zeolite of L type, zeolite of offretite-erionite mixed crystal type, zeolite of ferrierite type, zeolite of mordenite type, zeolite of clinoptilolite type, and zeolite of ZSM-5 type.

Method for removing nitrogen oxides from exhaust gases

A method for purifying an exhaust gas containing an excess amount of oxygen, to remove nitrogen oxides, carbon monoxide and hydrocarbons therefrom, by bringing a catalyst into contact with the exhaust gas, the catalyst comprising a zeolite ion-exchanged with (a) cobalt or (b) both cobalt and at least one metal selected from the group consisting of alkaline earth metals and rare earth metals, the zeolite being selected from the group consisting of ferrierite, ZSM-5, ZSM-11, ZSM-12 and ZSM-20, and having a silica-to-alumina molar ratio of from 15 to 1,000.

Method of purifying oxygen-excess exhaust gas

A process for catalytically reducing nitrogen oxides in an exhaust gas such as a combustion gas and a catalyst suitable for use therein. The catalyst comprises a zeolite Y which has been ion exchanged with lithium ions and/or rare earth metal ions, and may be dispersed in an amorphous oxide gel matrix.

Process for catalytic reduction of nitrogen oxides

A catalyst for reducing nitrogen oxides in waste gases is based on exchanged zeolite Y, if desired in a matrix with further doping.

Norbert Schwetje

Papers

Process for catalytic reduction of nitrogen oxides

Process for the catalytic reduction of nitrogen oxides