Abstract: The invention provides a redox catalyst for the selective reduction of the nitrogen oxides present in exhaust gas from diesel engines using ammonia. The reduction catalyst contains a catalytically active material which is based on the solid acid system TiO2/WO3/MoO3V2O5/SiO2/SO3 and an oxidation catalyst based on the platinum group metals platinum and palladium. The reduction catalyst is present in the form of a cylindrical honeycomb catalyst with an inlet and an outlet end face. The oxidation catalyst is applied to a section of the reduction catalyst adjacent to the outlet end face. The redox catalyst is characterised in that the catalytically active material in the reduction catalyst is used as support material for the platinum group metals in the oxidation catalyst.

Abstract: A catalyst for reducing nitrogen oxides in oxidizing and reducing atmospheres which contains iridium on a support material. Silicon dioxide or a dealuminized zeolite in the acid H form with a modulus of more than 20, preferably more than 100, or mixtures thereof are used as support materials. Iridium is deposited on the external surfaces of these support materials with average particle sizes between 10 and 30 nm. The catalyst is particularly suitable for treating exhaust gases from lean-burn gasoline engines or from diesel engines.

Abstract: The invention relates to a process for the selective catalytic reduction of the nitrogen oxides contained in a lean exhaust gas from internal combustion engines by reducing the nitrogen oxides by means of ammonia on a catalyst. The process is characterized in that, in addition to the lean exhaust gas, a rich gas stream is produced that is treated in an electrical gas discharge plasma in order to form the ammonia required for the reduction.

Abstract: A catalyst for reducing nitrogen oxides in oxidizing and reducing atmospheres which contains iridium on a support material. Silicon dioxide or a dealuminized zeolite in the acid H form with a modulus of more than 20, preferably more than 100, or mixtures thereof are used as support materials. Iridium is deposited on the external surfaces of these support materials with average particle sizes between 10 and 30 nm. The catalyst is particularly suitable for treating exhaust gases from lean-burn gasoline engines or from diesel engines.

Abstract: The invention concerns a process for the preparation of a vanadia SCR-catalyst supported on titania. The process is characterized in that the catalyst is prepared by dispersing titania in an ammonium metavanadate (NH4VO3) solution, adjusting the pH of the solution to a value of 7.0-7.1 by NH4OH and HNO3, stirring the resulting suspension for a time sufficient for complete adsorption of the vanadium compound on titania, filtering the suspension and drying and calcining the resulting catalyst compound.

Abstract: An oxidation catalyst for internal combustion engines which contains platinum on a finely divided support material and containing lead as a promoter. The catalytic activity of the oxidation catalyst can be increased greatly by promoting the catalyst with lead at a molar ratio of lead to platinum of 2:1. The light-off temperatures of the promoted catalyst are well below the corresponding temperatures for a conventional, lead-free catalyst.

Abstract: A process is disclosed for lowering nitrogen oxide levels in combustion engine exhaust gas by a reduction catalyst and by controlling the exhaust gas temperature upstream from the catalyst to a constant value, at which the catalyst exhibits maximum conversion for nitrogen oxides. It is possible to maintain maximum conversion over a wide range of engine outlet temperatures of the exhaust gas.