Abstract: The invention relates to a catalyst comprising at least two catalytically active layers, A and B, wherein A contains a carrier oxide and components A1 and A2, and B contains a carrier oxide and components B1, B2, and B3, wherein A1, A2, and B1 to B3 are defined as disclosed in claim 1. The proportion of component A1 in layer A is thereby greater than the proportion of component B1 in layer B, wherein the proportion of layer A with respect to the total weight of layers A and B, is greater than the proportion of layer B. The invention further relates to a method for reducing nitrogen oxides in exhaust gases of lean-burn internal combustion engines and to an exhaust gas cleaning system.

Abstract: The present invention relates to a nitrogen oxide storage catalyst composed of at least two catalytically active coatings on a support body, wherein a lower coating A contains cerium oxide, and platinum and/or palladium, but no alkaline earth metal compound, and an upper coating B which is disposed above coating A contains an alkaline earth metal compound, a basic mixed magnesium-aluminum oxide, and platinum and palladium, and to a method for converting NOx in exhaust gases of motor vehicles which are operated with lean-burn engines.

Abstract: The present invention relates to a catalyst system for treatment of diesel exhaust gas, comprising, in flow direction of the exhaust gas, a nitrogen oxide storage catalyst containing a nitrogen oxide storage component and noble metal and a diesel particulate filter containing noble metal selected from the group of platinum, palladium, and platinum and palladium, characterized in that the noble metal loading of the nitrogen oxide storage catalyst is 100 to 180 g/ft3 (3.53 to 6.36 g/L) and the noble metal loading of the diesel particulate filter is 5 to 35 g/ft3 (0.18 to 1.24 g/L).

Abstract: The invention relates to a catalyst comprising at least two catalytically active layers, A and B, wherein A contains a carrier oxide and components A1 and A2, and B contains a carrier oxide and components B1, B2, and B3, wherein A1, A2, and B1 to B3 are defined as disclosed in claim 1. The proportion of component A1 in layer A is thereby greater than the proportion of component B1 in layer B, wherein the proportion of layer A with respect to the total weight of layers A and B, is greater than the proportion of layer B. The invention further relates to a method for reducing nitrogen oxides in exhaust gases of lean-burn internal combustion engines and to an exhaust gas cleaning system.

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 invention relates to a method for removing carbon monoxide and hydrocarbons from the exhaust gas of lean-burn internal combustion engines, said exhaust gas being passed over a catalyst which contains platinum supported on one or more refractory supporting materials, pure cerium oxide, and optionally an additional noble metal selected from the group consisting of platinum, palladium and rhodium, wherein the pure cerium oxide is in close contact with the noble metal.

Abstract: The present invention relates to a catalytically active material consisting of an inner core (1) and an outer shell (2) surrounding this core, the core being formed from palladium and gold fixed together on a first support oxide, and the shell comprising platinum fixed on a second support oxide, to a diesel oxidation catalyst comprising this catalytically active material, and to an exhaust gas cleaning system comprising this diesel oxidation catalyst.

Abstract: The invention relates to a method for removing carbon monoxide and hydrocarbons from the exhaust gas of lean-burn internal combustion engines, said exhaust gas being passed over a catalyst which contains platinum supported on one or more refractory supporting materials, pure cerium oxide, and optionally an additional noble metal selected from the group consisting of platinum, palladium and rhodium, wherein the pure cerium oxide is in close contact with the noble metal.

Abstract: The present invention relates to a nitrogen oxide storage catalyst composed of at least two catalytically active coatings on a support body, wherein a lower coating A contains cerium oxide, and platinum and/or palladium, but no alkaline earth metal compound, and an upper coating B which is disposed above coating A contains an alkaline earth metal compound, a basic mixed magnesium-aluminum oxide, and platinum and palladium, and to a method for converting NOx in exhaust gases of motor vehicles which are operated with lean-burn engines.

Abstract: The present invention relates to a catalyst system for treatment of diesel exhaust gas, comprising, in flow direction of the exhaust gas, a nitrogen oxide storage catalyst containing a nitrogen oxide storage component and noble metal and a diesel particulate filter containing noble metal selected from the group of platinum, palladium, and platinum and palladium, characterized in that the noble metal loading of the nitrogen oxide storage catalyst is 100 to 180 g/ft3 (153 to 6.36 g/L) and the noble metal loading of the diesel particulate filter is 5 to 35 g/ft3 (0.18 to 1.24 g/L.).

Abstract: Proposed is a diesel particle filter which comprises a ceramic wall-flow filter substrate and a coating applied in the inflow ducts, which coating is composed of material with a high melting point. The coating (6) is provided such that, by means of said coating, pores (5), which connect the inflow ducts (1) and outflow ducts (2), in the wall (4) are closed off for the soot particles (7) at the inflow side without said coating thereby preventing the passage of the gaseous exhaust-gas constituents. The coating may be produced from one or more oxides with a high melting point or from fibrous material with a high melting point. In both cases, the coating has the effect that the depth filtration is considerably reduced, and therefore the back pressure increase encountered during the depth filtration phase is significantly reduced.

Abstract: The invention relates to a catalyst for purifying the exhaust gases from diesel engines, in particular an oxidation catalyst which is particularly well suited for the purification of exhaust gases from heavy goods vehicles when further exhaust gas purification units such as a particle filter and/or a nitrogen oxide reduction catalyst are installed downstream thereof. The catalyst contains two catalytically active coatings which have different compositions and of which only one is in direct contact with the outflowing exhaust gas. The coating (1) which is in direct contact with the outflowing exhaust gas is platinum-rich and contains a total amount of noble metal (platinum and palladium) which is greater than that in the coating (2) which is not in direct contact with the outflowing exhaust gas.

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 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: 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: 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: 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.