Abstract: 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.

Abstract: 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.

Abstract: The present invention relates to a zoned diesel oxidation catalyst, wherein the first catalytically active zone and the second catalytically active zone have equal thermal masses, the first catalytically active zone and the second catalytically active zone each contain platinum and palladium as catalytically active constituents, the weight ratio of platinum to palladium in the first catalytically active zone and the second catalytically active zone is the same in each case or is greater in the first catalytically active zone than in the second catalytically active zone, and the total concentration of platinum and palladium in the first catalytically active zone is greater than in the second catalytically active zone.

Abstract: The present invention relates to a catalytic converter which comprises a molecular sieve and a mixed oxide, and to a method for the selective catalytic reduction of nitrogen oxides in exhaust gases of diesel engines.

Abstract: A catalyst for the selective catalytic reduction of nitrogen oxides in diesel engine exhaust gases using ammonia or a precursor compound decomposable to ammonia. The catalyst includes two superposed coatings applied to a support body, of which the first coating applied directly to the support body includes a transition metal-exchanged zeolite and/or a transition metal-exchanged zeolite-like compound, and effectively catalyzes the SCR reaction. The second coating is applied to the first coating to cover it on the exhaust gas side and prevent hydrocarbons having at least three carbon atoms present in the exhaust gas from contacting the first coating, without blocking the passage of nitrogen oxides and ammonia to the first coating. The second coating may be formed from small-pore zeolites and/or small-pore, zeolite-like compounds, and from suitable oxides, especially silicon dioxide, germanium dioxide, aluminum oxide, titanium dioxide, tin oxide, cerium oxide, zirconium dioxide and mixtures thereof.

Abstract: The invention relates to a catalytically active material for reacting nitrogen oxides with ammonia in the presence of hydrocarbons. The material consists of an inner core (1) made of a zeolite exchanged with one or more transition metals or a zeolite-like compound exchanged with one or more transition metals. The core of the catalytically active material is encased by a shell (2), which is made of one or more oxides selected from silicon dioxide, germanium dioxide, aluminum oxide, titanium oxide, tin oxide, cerium oxide, zirconium dioxide, and mixed oxides thereof.

Abstract: An exhaust gas purification system (method and device) for the treatment of diesel exhaust gases containing nitrogen oxides and hydrocarbons is disclosed, which comprises the addition of ammonia or of a compound decomposable to ammonia into the exhaust gas stream and the subsequent leading of the exhaust gas stream over two successively arranged SCR catalysts with different properties and compositions. Both SCR catalysts are free of vanadium compounds and only the downstream SCR catalyst contains zeolite compounds. The exhaust gas purification system according to the invention is characterized by good “kick-off” behavior at low temperatures and a simultaneously high conversion performance over a wide temperature range.

Abstract: A process for improving catalytic activity of a copper-promoted zeolitic catalyst with a chabazite structure, the copper-promoted zeolitic catalyst having a temperature-programmed reduction (TPR) signal in a temperature range from 230° C. to 240° C. as examined in a TPR with a test gas having a hydrogen content of 5% by volume, a heating rate of 10 K/min, and a catalyst sample weight containing from 3 to 8 milligrams of copper calculated as metal.

Abstract: The present invention relates to a catalytic converter which comprises a molecular sieve and a mixed oxide, and to a method for the selective catalytic reduction of nitrogen oxides in exhaust gases of diesel engines.

Abstract: The invention relates to the use of mixed oxides made of cerium oxide, zirconium oxide, rare earth sesquioxide and niobium oxide as catalytically active materials for the selective catalytic reduction of nitrogen oxides with ammonia or a compound that can decompose to form ammonia in the exhaust gas of internal combustion engines in motor vehicles that are predominantly leanly operated, and to compositions or catalysts which contain said mixed oxides in combination with zeolite compounds and/or zeolite-like compounds and are suitable for the denitrogenation of lean motor vehicle exhaust gases in all essential operating states.

Abstract: The invention relates to a catalytically active material for reacting nitrogen oxides with ammonia in the presence of hydrocarbons. The material consists of an inner core (1) made of a zeolite exchanged with one or more transition metals or a zeolite-like compound exchanged with one or more transition metals. The core of the catalytically active material is encased by a shell (2), which is made of one or more oxides selected from silicon dioxide, germanium dioxide, aluminum oxide, titanium oxide, tin oxide, cerium oxide, zirconium dioxide, and mixed oxides thereof.

Abstract: A catalyst for the selective catalytic reduction of nitrogen oxides in diesel engine exhaust gases using ammonia or a precursor compound decomposable to ammonia is described. The catalyst comprises two superposed coatings applied to a support body, of which the first coating applied directly to the support body comprises a transition metal-exchanged zeolite and/or a transition metal-exchanged zeolite-like compound, and effectively catalyzes the SCR reaction. The second coating has been applied to the first coating so as to cover it on the exhaust gas side. It is configured so as to prevent the contact of hydrocarbons having at least three carbon atoms present in the exhaust gas with the layer beneath, without blocking the passage of nitrogen oxides and ammonia to the first coating.

Abstract: Selective catalytic reduction with ammonia or a compound that decomposes to ammonia is a known method for the removal of nitrogen oxides from the exhaust gas of primarily lean-burn internal combustion engines. The vanadium-containing SCR catalysts that have long been generally used for this are characterized by a good conversion profile. However, the volatility of vanadium oxide can, at higher exhaust gas temperatures, lead to the emission of toxic vanadium compounds. Zeolite-based SCR catalysts, which are used in particular in discontinuous SCR systems, constitute a very cost-intensive solution for the problem. A method is proposed by which a homogeneous cerium-zirconium mixed oxide is activated for the SCR reaction in a defined manner by the introduction of sulphur and/or transition metal.

Abstract: The reductive removal of nitrogen oxides from the exhaust gas from internal combustion engines operated predominantly under lean conditionstakes place in a selective catalytic reduction (SCR) of the nitrogen oxides by means of ammonia or a compound which can be decomposed into ammonia as reducing agent. Conventional SCR catalysts typically have a relatively narrow working temperature window, usually 350° C. to 520° C., in which good nitrogen oxide conversions can be achieved with sufficient selectivity. SCR catalyst formulations whose working window is in the temperature range from 150° C. to 350° C. generally not be used at higher temperatures since they oxidize the ammonia required as reducing 18 agent to nitrogen oxides at above 350° C. To cover the entire exhaust gas temperature range typical of vehicles having been operating internal combustion enginesextending from 200° C. to 600° C.

Abstract: The present invention relates to a process for improving the catalytic activity of a copper-promoted zeolitic catalyst with chabazite structure, to a copper-promoted zeolitic catalyst with chabazite structure and to a process for reducing nitrogen oxides in an offgas stream.

Abstract: The invention relates to the use of mixed oxides made of cerium oxide, zirconium oxide, rare earth sesquioxide and niobium oxide as catalytically active materials for the selective catalytic reduction of nitrogen oxides with ammonia or a compound that can decompose to form ammonia in the exhaust gas of internal combustion engines in motor vehicles that are predominantly leanly operated, and to compositions or catalysts which contain said mixed oxides in combination with zeolite compounds and/or zeolite-like compounds and are suitable for the denitrogenation of lean motor vehicle exhaust gases in all essential operating states.

Abstract: Structured automotive catalysts which comprise a plurality of different catalytically active coatings arranged above one another on a support body and whose coatings contain transition metals and porous support materials are well known. Structured automotive catalysts of this type which do not belong to the group of three-way catalysts, in particular, frequently display large selectivity losses after thermal aging processes which can be attributed to the thermally induced migration of transition metal atoms from one layer into the neighboring coating. The introduction of a diffusion barrier which slows or prevents the thermally induced migration of transition metal atoms from one catalytically active layer into the other increases the thermal aging stability of such catalysts significantly.

Abstract: A catalytically active diesel particulate filter with ammonia trap action is presented, which, in addition to an oxidation-active coating (2), comprises a coating (1) which is catalytically active in the SCR reaction. By means of this inventive diesel particulate filter, it is possible to make exhaust gas aftertreatment systems for removing nitrogen oxides and particulates from the exhaust gas of lean engines considerably simpler and less expensive.

Abstract: An exhaust gas purification system (method and device) for the treatment of diesel exhaust gases containing nitrogen oxides and hydrocarbons is disclosed, which comprises the addition of ammonia or of a compound decomposable to ammonia into the exhaust gas stream and the subsequent leading of the exhaust gas stream over two successively arranged SCR catalysts with different properties and compositions. Both SCR catalysts are free of vanadium compounds and only the downstream SCR catalyst contains zeolite compounds. The exhaust gas purification system according to the invention is characterized by good “kick-off” behavior at low temperatures and a simultaneously high conversion performance over a wide temperature range.

Abstract: A catalyst and a process for selective catalytic reduction of nitrogen oxides in diesel engine exhaust gases with ammonia or a compound decomposable to ammonia are described. The exhaust gas to be cleaned is passed together with ammonia or a compound decomposable to ammonia over a catalyst which comprises a zeolite or a zeolite-like compound containing 1-10% by weight of copper, based on the total weight of the zeolite or of the zeolite-like compound, and a homogeneous cerium-zirconium mixed oxide and/or a cerium oxide. The zeolite used or the zeolite-like compound used is selected from the group consisting of chabazite, SAPO-34, ALPO-34 and zeolite-?.