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: 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 present invention is directed to a particle filter to remove soot from the exhaust gas of a diesel engine. The particle filter contains a catalytically active coating on a filter body to accelerate bum-off during a regeneration phase of the soot particles collected on the filter. The particle filter comprises a catalytic coating containing compounds of barium, compounds of magnesium, and at least one element of the platinum group metals. The invention is further directed to a process for accelerated combustion of soot particles collected on the filter from lean exhaust gas of a diesel engine in which the soot particles have a soot ignition temperature and the particle filter is actively regenerated from time to time by raising the temperature of the particle filter above the soot ignition temperature and burning off the soot particles.

Abstract: The invention relates to a catalyst for lowering the amount of NOx in the lean exhaust gas from lean burn engines, comprising active aluminum oxide, magnesium oxide and at least one noble metal of the platinum group of the periodic table of the elements, as well as at least one nitrogen oxide storage material. The catalyst is characterized in that the magnesium oxide forms a homogeneous mixed oxide with aluminum oxide and is present in a concentration of about 1 to about 40 wt.-%, based on the total weight of the mixed oxide.

Abstract: The present invention is directed to a particle filter to remove soot from the exhaust gas of a diesel engine. The particle filter contains a catalytically active coating on a filter body to accelerate bum-off during a regeneration phase of the soot particles collected on the filter. The particle filter comprises a catalytic coating containing compounds of barium, compounds of magnesium, and at least one element of the platinum group metals. The invention is further directed to a process for accelerated combustion of soot particles collected on the filter from lean exhaust gas of a diesel engine in which the soot particles have a soot ignition temperature and the particle filter is actively regenerated from time to time by raising the temperature of the particle filter above the soot ignition temperature and burning off the soot particles.

Abstract: The present invention provides processes for checking the operability of a nitrogen oxide storage catalyst during operation of a lean burn engine. The processes of the present invention utilize a nitrogen oxide storage material, a catalytically active component and optionally an oxygen storage material. During lean burn engine operation, damage to the catalytically active components is detected if the nitrogen oxide storage capacity in the kinetically controlled temperature range is lowered and damage to the storage material is detected if the nitrogen oxide storage capacity is lowered in the thermodynamically controlled temperature range.

Abstract: A method for producing a nitrogen oxide storage material that contains at least one storage component in the form of particles of an oxide, carbonate or hydroxide of the elements magnesium, strontium, barium, lanthanum and cerium on a carrier material from the group consisting of doped cerium oxide, cerium/zirconium mixed oxide and aluminum oxide or mixtures of these. The method is carried out by suspending the support material in an aqueous solution of precursors of the storage components, this suspension is then introduced into a hot gas stream, the temperature of which is calculated so that, during a residence time of the suspension in the hot gas stream of less than one minute, the solvent of the suspension is evaporated out and the precursors of the storage components are thermally broken down and converted to the storage components before the storage material that forms in this way is separated from the stream of hot gases.

Abstract: The invention relates to a catalyst for lowering the amount of NOx in the lean exhaust gas from lean burn engines, comprising active aluminum oxide, magnesium oxide and at least one noble metal of the platinum group of the periodic table of the elements, as well as at least one nitrogen oxide storage material. The catalyst is characterized in that the magnesium oxide forms a homogeneous mixed oxide with aluminum oxide and is present in a concentration of about 1 to about 40 wt.-%, based on the total weight of the mixed oxide.

Abstract: A process is disclosed for checking the operatability of a nitrogen oxide storage catalyst which is used to remove the nitrogen oxides contained in the exhaust gas stream from a lean burn engine and which contains at least a nitrogen oxide storage material, a catalytically active component and optionally an oxygen storage material. The lean burn engine is operated with cyclic alternation of the air/fuel mixture from lean to rich and the nitrogen oxides contained in the exhaust gas are stored by the nitrogen oxide storage material in the presence of lean burn exhaust gas (storage phase) and is desorbed and converted in the presence of rich exhaust gas (regeneration phase).