Abstract: An exhaust-gas cleaning system removes at least nitrogen oxides contained in exhaust-gas from a combustion source. An ammonia-generation catalytic converter generates ammonia using constituents of at least some of the exhaust gas emitted from the combustion source during ammonia-generation operating phases. Downstream a nitrogen oxide reduction catalytic converter reduces nitrogen oxides which are contained in the exhaust gas emitted from the combustion source using the ammonia generated as reducing agent. A nitrogen monoxide generation unit is situated outside the combustion source, for enriching the exhaust gas which is fed to the ammonia-generation catalytic converter with generated nitrogen monoxide during the ammonia-generation operating phases. The system is used for cleaning exhaust gases of motor vehicle internal-combustion engines which are operated predominantly in lean-burn mode, removing nitrogen oxides which are contained therein.

Abstract: In a method for the periodic desulphurization of a nitrogen-oxide or sulphur-oxide accumulator of an exhaust-gas cleaning system of an internal-combustion engine, during respective desulphurization periods, the accumulator is fed secondary air by secondary-air supply means, and is fed an engine exhaust gas which contains a reducing agent by setting a rich engine air ratio. At least during part of the desulphurization period, after a predeterminable desulphurization temperature has been reached, the accumulator air ratio is set, by suitably alternating the secondary air quantity supplied and/or the engine air ratio, between an oxidizing or stoichiometric atmosphere, and a reducing atmosphere.

Abstract: In a method for burning deposited soot particles in a particle filter on an exhaust device of a diesel engine, first of all, in a known way, a catalytic converter produces NO2 from exhaust gas. This NO2 reduces the ignition temperature of soot to such an extent that it burns at normal exhaust-gas temperature. Furthermore, there is provision to add fuel additive, which likewise allows the ignition temperature of the soot to be reduced. The sulphur content in the fuel is determined, and either generation of NO2 or the addition of additive is used as a function of this measurement. This preferably takes place automatically. To determine the sulphur content, it is possible, for example, to use a sulphur sensor in the tank.

Abstract: A method for the desulfurization of a nitrogen oxide adsorber of an exhaust gas purification device for a combustion system employs desulfurization phases that are intermittently implemented by a desulfurization control unit. During each desulfurization phase, the carbon monoxide concentration and/or the lambda value of the exhaust gas stream exiting the nitrogen oxide adsorber is recorded. A localized maximum that appears in the recorded course of the carbon monoxide concentration over time, or a downward slope that appears in the established course of the lambda value over time, falling from a temporary plateau value, is employed as criterion for terminating the desulfurization phase. The method may be used, for example, in exhaust gas purification devices in primarily lean-burning vehicle combustion engines.

Abstract: An exhaust-gas aftertreatment device with a nitrogen oxide storage catalytic converter for an internal combustion engine, and a method for operating an exhaust-gas aftertreatment device which is assigned to an internal combustion engine and has a nitrogen oxide storage catalytic converter. An SCR catalytic converter is arranged in the exhaust-gas aftertreatment device, it being possible for the exhaust gas which emerges from the nitrogen oxide storage catalytic converter to be fed to the SCR catalytic converter when the internal combustion engine is in a desulphating operating mode with a reducing exhaust-gas composition, in order for H2S which is formed during the desulphating to be removed.

Abstract: A solid material for adsorption of nitrogen oxides in an oxidizing atmosphere and desorption of nitrogen oxides in a reducing atmosphere in gases, such as internal combustion engine exhaust gases, can comprise a porous support, at least one metal component, and at least one transition metal component. A process for adsorption and desorption of nitrogen oxides in gases, such as internal combustion engine exhaust gases, can comprise the use of at least one solid material.

Abstract: An exhaust gas purification device in a vehicle, wherein a reforming reactor is provided for extraction of hydrogen from fuel and the hydrogen is supplied to an exhaust gas stream of an internal combustion engine upstream of the exhaust gas catalytic converter, wherein the reforming reactor includes a supply device for oxygen and/or water, wherein the reforming reactor is connected with a side branch of the exhaust gas conduit and wherein oxygen and water for reforming are supplied in the form of an exhaust gas partial stream via the side branch.

Abstract: A method for the desulfurization of a nitrogen oxide adsorber of an exhaust gas purification device for a combustion system employs desulfurization phases that are intermittently implemented by a desulfurization control unit. During each desulfurization phase, the carbon monoxide concentration and/or the lambda value of the exhaust gas stream exiting the nitrogen oxide adsorber is recorded. A localized maximum that appears in the recorded course of the carbon monoxide concentration over time, or a downward slope that appears in the established course of the lambda value over time, falling from a temporary plateau value, is employed as criterion for terminating the desulfurization phase. The method may be used, for example, in exhaust gas purification devices in primarily lean-burning vehicle combustion engines.

Abstract: A method for operating an exhaust-gas cleaning system having an NOx adsorption accumulator and an SOx trap, includes, in normal operating phases, feeding the exhaust gas to be cleaned first via the SOx trap and then via the NOx adsorption accumulator. The normal operating phases are from time to time interrupted by desulphurization phases for desulphurizing the SOx trap. Means are provided for controlling the direction of flow of the exhaust stream so that it optionally passes firstly via the SOx trap and then via the NOx adsorption accumulator, or firstly via the NOx adsorption accumulator and then via the SOx trap, so that during the desulphurization phases the exhaust gas can be passed firstly via the NOx adsorption accumulator and then via the SOx trap.

Abstract: A filter assembly for an exhaust gas purification system of an internal combustion engine. The filter assembly, has porous filter plate elements, connected with each other on their outer as well as on their inner peripheries, forming in pairs as filter pockets. Catalytic agents such as ammonia are applied to the filter pockets on the outer and/or inner sides to oxidize carbon black contained in the combustion gas. In particular, this filter assembly is compact and can be used for diesel engines of motor vehicles.

Abstract: A method and apparatus for purifying an exhaust gas of an internal combustion engine includes an ammonia generating catalyst for generating ammonia from nitrogen oxides contained in the exhaust gas to be purified, and a nitrogen oxide reducing catalyst downstream of the ammonia generating catalyst, for reduction of nitrogen oxides contained in the exhaust gas to be purified. Generated ammonia is used as the reducing agent. A nitrogen oxide adsorption catalyst is arranged upstream of the ammonia generating catalyst, or the ammonia generating catalyst is arranged in an exhaust pipe branch which pertains to only a part of several separately controllable internal-combustion sources. One or more additional exhaust pipe branches assigned to the other internal-combustion sources and lead to the nitrogen oxide reducing catalyst, while bypassing the ammonia generating catalyst.

Abstract: An internal-combustion engine includes an engine control system that permits a change-over between a lean operation and a rich operation of the internal-combustion engine, and an exhaust gas purification system. A &lgr;-probe, an SOx storage catalyst and an NOx storage catalyst are successively arranged in an exhaust gas line behind the engine. At the start of desulfurization of the SOx storage catalyst, a change-over takes place from the lean to the rich operation of the engine. Secondary air is fed into the exhaust gas line; a predetermined &lgr; value of the exhaust gases mixed with secondary air and a temperature in the SOx storage catalyst are measured. At the end of the desulfurization, a change-over takes place from the rich to a lean operation of the engine.

Abstract: A method for operating an exhaust-gas cleaning system having an NOX adsorption accumulator and an SOX trap, includes, in normal operating phases, feeding the exhaust gas to be cleaned first via the SOX trap and then via the NOX adsorption accumulator. The normal operating phases are from time to time interrupted by desulphurization phases for desulphurizing the SOX trap. Means are provided for controlling the direction of flow of the exhaust stream so that it optionally passes firstly via the SOX trap and then via the NOX adsorption accumulator, or firstly via the NOX adsorption accumulator and then via the SOX trap, so that during the desulphurization phases the exhaust gas can be passed firstly via the NOX adsorption accumulator and then via the SOX trap.

Abstract: The invention relates to a method of operating a diesel engine having an engine controller which controls the operation of the diesel engine as a function of characteristic maps and permits rich/lean control of the diesel engine. The engine controller includes a computer which effects a changeover to rich or lean operation of the diesel engine as a function of predetermined changeover criteria, a sensor system which communicates with the computer and monitors parameters needed for changeover criteria, and a memory which communicates with the computer and in which the characteristic maps for operating the diesel engine are stored. The computer effects a changeover from lean to rich operation when all the changeover criteria in this respect are satisfied, and effects a change back from rich to lean operation when at least one of the changeover criteria in this respect is satisfied.

Abstract: A method of cleaning an exhaust gas from a combustion system that is operated alternately in lean and rich conditions includes intermediately storing nitrogen oxides during lean operation; releasing the stored nitrogen oxides, thereby producing ammonia and storing the ammonia during rich operation; releasing the ammonia, thereby reducing nitrogen oxides in a subsequent lean condition.

Abstract: An emission control system for an internal-combustion engine has at least one nitrogen oxide adsorber for the periodic adsorption and desorption of nitrogen oxides contained in the exhaust gas of the internal-combustion engine. A desorption gas pipe has an externally heatable catalyst arranged therein to which a mixture of air and/or exhaust gas can be fed as well as fuel at an at least stoichiometric proportion. This mixture is burned to form a desorbing gas flow which is fed to the respective nitrogen oxide adsorber for the nitrogen oxide desorption.

Abstract: An internal-combustion engine system includes an internal-combustion engine with a pertaining engine exhaust gas system, an emissions control device having an NO.sub.x storage catalyst arranged in the exhaust gas system, a lambda probe for detecting the engine air ratio and devices for the periodic desulfurization of the catalyst at a raised temperature and a rich air ratio of the latter, as well as to an operating process suitable for this system. The desulfurization devices comprise secondary air feeding devices for feeding secondary air into the NO.sub.x storage catalyst. During the desulfurization phases, the engine is operated at a rich air ratio and secondary air is metered into the catalyst.

Abstract: A multi-cylinder air-compressing injection-type internal-combustion engine having a nitric oxide adsorber catalyst and an exhaust gas return device. In order to increase the hydrocarbon fraction in the exhaust gas in front of an exhaust gas aftertreatment device during a regeneration phase and to reduce the oxygen content, exhaust gas pipes of the cylinders are divided into at least two flows, which extend separately from one another at least along a distance. An increased hydrocarbon emission is generated exclusively in the cylinders of one of the flows at times. Another of the flows is connected by way of the exhaust gas return device with an air intake pipe of the internal-combustion engine.

Abstract: An internal-combustion engine includes an engine control system that permits a change-over between a lean operation and a rich operation of the internal-combustion engine, and an exhaust gas purification system. A .lambda.-probe, an SO.sub.x storage catalyst and an NO.sub.x storage catalyst are successively arranged in an exhaust gas line behind the engine. At the start of desulfurization of the SO.sub.x storage catalyst, a change-over takes place from the lean to the rich operation of the engine. Secondary air is fed into the exhaust gas line; a predetermined .lambda. value of the exhaust gases mixed with secondary air and a temperature in the SO.sub.x storage catalyst are measured. At the end of the desulfurization, a change-over takes place from the rich to a lean operation of the engine.

Abstract: A method for operating a multicylinder internal combustion engine with at least one adsorber catalytic converter in the exhaust line of the internal combustion engine includes operating the adsorber catalytic converter with periodically alternating adsorption and desorption operation. The exhaust leaving the adsorber catalytic converter in desorption operation is recycled and/or an oxidation catalytic converter is provided upstream of the adsorber catalytic converter. Exhaust recycling takes place occurs selectively in only one set of the cylinders of the internal combustion engine and this set of cylinders is operated in a state of incomplete combustion during desorption operation. Rich afterburning may be performed during desorption operation of the adsorber catalytic converter in the oxidation catalytic converter connected upstream and the oxidation catalytic converter is operated at an increased temperature during short regeneration phases to remove soot.