Degussa Aktiengesellschaft

Degussa - Huls Ag

Dmc, Inc

Dmc2 Degussa Metals Catalysts Cerdec Ag

Omg Ag & Co Kg

Degussa-huls-aktiengesellshaft

Ulrich G&ouml;bel

Wolfgang Strehlau

Thomas Kreuzer

Egbert Lox

Rainer Domesle

Lothar Mussmann

Lutz Marc Ruwisch

Martin Foerster

Ralph Kiessling

Adolf Sch&auml;fer-Sindlinger

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.

Process for checking the operatability of a nitrogen oxide storage catalyst

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.

Method for producing a nitrogen oxide storage material and a storage material made with it

A process for removing soot from the exhaust gas of a diesel engine by oxidizing the nitrogen monoxide present in the exhaust gas to nitrogen dioxide, separating the soot from the exhaust gas stream and oxidizing the soot using the nitrogen dioxide produced. The process is performed in at least two consecutive process stages and the soot is separated from the exhaust gas stream with an efficiency W between 0.05 and 0.95 in each process stage, wherein each process stage can be assigned a transmission for soot in accordance with T&equals;1&minus;W and the total transmission of the process for soot is given as the product of the transmissions of all the process stages.

Process and device for removing soot from the exhaust gas of a diesel engine

A powdered catalyst material based on aluminum oxide, which contains at least one basic metal oxide and at least one noble metal from the platinum group of the Periodic Table of Elements in addition to aluminum oxide. The catalyst material is obtainable by loading a support material already stabilized by basic oxides by renewed impregnation with further basic oxides. After drying and calcining this post-impregnated material at temperatures below &deg; C., the catalytically active noble metals are also incorporated into the support material by impregnation.

Catalyst material

A nitrogen oxide storage catalyst which contains at least one catalyst material and at least one nitrogen oxide storage component from the group of alkali and alkaline earth metals. The nitrogen oxide storage component, after completing catalyst preparation, is present as finely divided barium sulfate, strontium sulfate, a mixture or mixed crystals of the two sulfates, or as their complete or incomplete decomposition product with an average particle size of less than 1 &mgr;m. Barium sulfate and/or strontium sulfate act as feed materials for the active storage component in the storage catalyst according to the invention. As a result of the reductive exhaust gas compositions occurring under normal automobile driving conditions barium sulfate and strontium sulfate decompose to compounds which are able to store nitrogen oxides. This compensates for the loss of active storage components which occurs due to aging. Barium sulfate and/or strontium sulfate may be decomposed during production by means of reductive calcination in order to obtain a high initial loading of the catalyst with storage compounds. In this case, these sulfates are used as auxiliary agents in order to introduce the highest possible concentrations of storage compounds into the storage catalyst.

Nitrogen oxide storage catalyst

A nitrogen oxide storage material is disclosed which contains at least one storage component for nitrogen oxides in the form of an oxide, mixed oxide, carbonate or hydroxide of the alkaline earth metals magnesium, calcium, strontium and barium and the alkali metals potassium and caesium on a high surface area support material. The support material can be doped cerium oxide, cerium/zirconium mixed oxide, calcium titanate, strontium titanate, barium titanate, barium stannate, barium zirconate, magnesium oxide, lanthanum oxide, praseodymium oxide, samarium oxide, neodymium oxide, yttrium oxide, zirconium silicate, yttrium barium cuprate, lead titanate, tin titanate, bismuth titanate, lanthanum cobaltate, lanthanum manganate and barium cuprate or mixtures thereof.

Nitrogen oxide storage material and nitrogen oxide storing catalyst prepared therefrom

A sulfur oxide storage material contains a magnesium-aluminum spinel (MgO.Al O ) and can be used as a so-called &ldquo;sulfur trap&rdquo; to remove sulfur oxides from oxygen-containing exhaust gases of industrial processes. In particular, it can be used for the catalytic purification of exhaust gas from internal-combustion engines to remove the sulfur oxides from the exhaust gas in order to protect the exhaust gas catalysts from sulfur poisoning. The material displays a molar ratio of magnesium oxide to aluminum oxide in the range of over 1.1:1, and the magnesium oxide present in stoichiometric excess is homogeneously distributed in a highly disperse form in the storage material.

Storage material for sulfur oxides

A process for evaluating performance deterioration of a nitrogen oxide storage catalyst which has a nitrogen oxide storage function and an oxygen storage function and is operated with cyclic alternation of the air/fuel ratio in the exhaust gas from lean to rich. The nitrogen oxides are stored during the lean phase and the nitrogen oxides are desorbed and converted during the rich phase. To check the serviceability of the storage catalyst, the air/fuel ratio of the exhaust gas is switched from lean to rich and the rich phase is extended beyond the time required for complete desorption of the nitrogen oxides until at least the rich exhaust gas passes right through the catalyst and the time interval &Dgr;t,produced between the first change-over until breakthrough of the rich exhaust gas and, after again switching from rich to lean running, the time interval &Dgr;t,produced between the second change-over and passage of oxygen through the catalyst are measured and the time differences &Dgr;t,and &Dgr;t,are used for separate assessment of the oxygen storage function and the nitrogen oxide storage function of the catalyst.

Growing community of inventors

Hattersheim, Germany

Ulrich Göbel

Growing community of inventors

Hattersheim, Germany

Ulrich G&ouml;bel

Ulrich Göbel