Abstract: The invention relates to a process for coating ceramic honeycomb bodies with a coating suspension containing, in a carrier liquid, catalyst components as solids and/or in dissolved form. The honeycomb bodies have parallel flow channels running through them. The walls of the flow channels generally have an open pore structure. To coat the channel walls and in particular also the interior surfaces of the pores with the coating suspension, it is proposed that the flow channels be temporarily alternately closed and the coating suspension be forced through the open pore structure of the channel walls. The coating is subsequently dried and calcined. To close the flow channels, it is possible to use thermally or chemically decomposable or soluble compositions which are decomposed or dissolved either during calcination or by means of a subsequent chemical treatment. The coated honeycomb bodies are preferably used for the purification of exhaust gases from automobiles.

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: The invention proposes a particulate filter having a catalytic coating which contains two catalysts arranged one behind the other. The first catalyst is located in the gas inlet region of the filter and contains a palladium/platinum catalyst. The second catalyst is arranged downstream of the first catalyst and preferably contains platinum alone as catalytically active component. The combination of these two catalysts provides the coated filter with a good ageing stability and resistance to sulphur poisoning.

Abstract: A diesel particulate filter with an oxidation catalyst comprising platinum and palladium deposited thereon is described. Addition of HC storage components to the oxidation catalyst allows the conversion of hydrocarbons and carbon monoxide to be improved significantly.

Abstract: A diesel particulate filter with an oxidation catalyst comprising platinum and palladium deposited thereon is described. Addition of HC storage components to the oxidation catalyst allows the conversion of hydrocarbons and carbon monoxide to be improved 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: A nitrogen oxide storage catalytic converter which is operated for a relatively long time at low exhaust-gas temperatures in the range between 120 and 250° C. exhibits a decreasing storage capacity as a result of incomplete regeneration at said temperatures. In order to re-establish the original storage capacity of the catalytic converter which is operated in this way, two-stage regeneration is proposed, wherein the storage catalytic converter is initially partially regenerated at the low exhaust gas temperature by means of a switch from the lean mode to the rich mode, and wherein subsequently, with rich exhaust gas again, the exhaust-gas temperature of the engine is raised into a range of between 300 and 400° C. for complete regeneration.

Abstract: The invention relates to a process for coating ceramic honeycomb bodies with a coating suspension containing, in a carrier liquid, catalyst components as solids and/or in dissolved form. The honeycomb bodies have parallel flow channels running through them. The walls of the flow channels generally have an open pore structure. To coat the channel walls and in particular also the interior surfaces of the pores with the coating suspension, it is proposed that the flow channels be temporarily alternately closed and the coating suspension be forced through the open pore structure of the channel walls. The coating is subsequently dried and calcined. To close the flow channels, it is possible to use thermally or chemically decomposable or soluble compositions which are decomposed or dissolved either during calcination or by means of a subsequent chemical treatment. The coated honeycomb bodies are preferably used for the purification of exhaust gases from automobiles.

Abstract: A nitrogen oxide storage catalytic converter which is operated for a relatively long time at low exhaust-gas temperatures in the range between 120 and 250° C. exhibits a decreasing storage capacity as a result of incomplete regeneration at said temperatures. In order to re-establish the original storage capacity of the catalytic converter which is operated in this way, two-stage regeneration is proposed, wherein the storage catalytic converter is initially partially regenerated at the low exhaust gas temperature by means of a switch from the lean mode to the rich mode, and wherein subsequently, with rich exhaust gas again, the exhaust-gas temperature of the engine is raised into a range of between 300 and 400° C. for complete regeneration.

Abstract: The invention proposes a particulate filter having a catalytic coating which contains two catalysts arranged one behind the other. The first catalyst is located in the gas inlet region of the filter and contains a palladium/platinum catalyst. The second catalyst is arranged downstream of the first catalyst and preferably contains platinum alone as catalytically active component. The combination of these two catalysts provides the coated filter with a good ageing stability and resistance to sulphur poisoning.

Abstract: Coating a wall-flow filter with a catalytically active coating generally increases the exhaust-gas backpressure in the filter. The increase in the exhaust-gas backpressure is particularly pronounced if a slurry of fine-particle catalyst materials is used for the coating operation. The increase in the exhaust-gas backpressure can be restricted to a tolerable level if, prior to the coating operation, the slurry is so finely milled that virtually the entire mass of the catalyst materials is introduced into the pores of the filter and deposited on the inner surfaces of the pores. This is the case if the d90 diameter of the particles in the slurry is reduced to below 5 ?m by milling.

Abstract: A process is described for reducing the NOx concentration and N2O concentration from the residual gas from nitric acid production. The process encompasses the passing of the residual gas leaving the absorption column, prior to entry into the residual gas turbine, through a combination of two stages. The first stage here reduces the NOx content and the second stage the N2O content of the gas, the NOx/N2O ratio prior to entry of the gas into the second stage being in the range from 0.001 to 0.5, and this gas being brought into contact in the second stage with a catalyst which is substantially composed of one or more iron-loaded zeolites.

Abstract: The quality of a weld is usually monitored via the different wavelength radiation issuing from the weld point. During the welding of workpieces, however, this radiation (S) is also modulated by the instantaneous width (b) of the gap existing between the workpieces. To avoid the generation of unnecessary fault signals (F) on the one hand and excessive tolerance bands for the permitted signal range on the other hand, the invention proposes that a correction formula (.increment.S(B)) which reproduces the dependency of the radiation signals (S) on the gap width (B) be produced in a preliminary test. The gap width (B) in the weld point is defined during welding. A correction value (.increment.S(B)) is defined during the welding process on the basis of the correction formula (.increment.S(B)) and the instantaneous gap width (B) in the weld point and the limit values (MAx(B.sub.0), MIN(B.sub.0) previously defined for a gap width zero are displaced by this correction value (.increment.S(B)).