Umicore Ag & Co. Kg

Degussa Aktiengesellschaft

Degussa - Huls Ag

Dmc, Inc

Dmc2 Degussa Metal Catalysts Cerdec Ag

Degussa-h{umlaut Over (u)}ls Aktiengesellschaft

Degussa-huls-aktiengesellshaft

Degussa Aktiengesellscaft

Dmc2 Degussa Metals Catalysts Cerdac Ag

Lothar Mussmann

Egbert Lox

Thomas Kreuzer

Dieter Lindner

Martin Votsmeier

Renee Van Yperen

Ulrich G&ouml;bel

Rainer Domesle

Marcus Pfeifer

Nicola Soeger

Gerald Jeske

Wolfgang Strehlau

Mamoun Muhammed

Katja Adelmann

Wilfried Mueller

Wolfgang Schneider

Andreas Geisselmann

Matthias Feger

Ingo Lappas

Tassilo Bog

Michael Schiffer

Michael Harris

Ralf Sesselmann

Othan Adamopoulos

Othon Adamopoulos

Jorg-Michael Richter

Joerg Michael Richter

A process which solves the problem of supplying NOin accordance with requirements by means of temperature control of the precatalyst which is decoupled from the operating state of the engine. In an associated apparatus, a precatalyst which contains at least one oxidation component and whose temperature can be controlled independently of the operating state of the engine and an active SCR stage comprising an SCR catalyst with upstream metering facility for a reducing agent from an external source are arranged in series. A particle filter can be arranged between precatalyst and metering facility. The precatalyst preferably additionally contains a nitrogen oxide storage material.

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The adherence to future legally obligatory exhaust gas limit values for diesel vehicles in Europe, North America and Japan requires not only the removal of particles but also effective removal of nitrogen oxides from the exhaust gas ('deNOx'). The 'active SCR process' is the preferred method for this. The nitrogen oxide conversions achieved by means of this process are particularly high when an optimal NO/NOratio, preferably 0.5, is set upstream of the SCR catalyst. The invention proposes a process which solves the problem of supplying NOin accordance with requirements by means of temperature control of the precatalyst which is decoupled from the operating state of the engine. In an associated apparatus, a precatalyst () which contains at least one oxidation component and whose temperature can be controlled independently of the operating state of the engine and an active SCR stage comprising an SCR catalyst () with upstream metering facility () for a reducing agent from an external source () are arranged in series. A particle filter () can be arranged between precatalyst and metering facility. The precatalyst preferably additionally contains a nitrogen oxide storage material.

The reductive removal of nitrogen oxides from the exhaust gas from internal combustion engines operated predominantly under lean conditionstakes place in a selective catalytic reduction (SCR) of the nitrogen oxides by means of ammonia or a compound which can be decomposed into ammonia as reducing agent. Conventional SCR catalysts typically have a relatively narrow working temperature window, usually 350&#xb0; C. to 520&#xb0; C., in which good nitrogen oxide conversions can be achieved with sufficient selectivity. SCR catalyst formulations whose working window is in the temperature range from 150&#xb0; C. to 350&#xb0; C. generally not be used at higher temperatures since they oxidize the ammonia required as reducing 18 agent to nitrogen oxides at above 350&#xb0; C. To cover the entire exhaust gas temperature range typical of vehicles having been operating internal combustion enginesextending from 200&#xb0; C. to 600&#xb0; C., it has therefore mostly been necessary to use complicated exhaust gas systemscontaining a plurality of catalysts having different working temperature ranges. Disclosed is a structured SCR catalyst whose working range extends over a significantly broader temperature window and by means of which complicated exhaust gas units can be considerably simplified, with a saving of components.

Structured SCR catalyst for the reduction of nitrogen oxides in the exhaust gas from lean-burn engines using ammonia as reducing agent

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. Using this method, a highly active, ageing-resistant SCR catalyst is provided, which represents a vanadium-free, cost-effective and high-performance alternative to the existing SCR catalysts and is suitable in particular for use in motor vehicles.

Vanadium-free catalyst for selective catalytic reduction and process for it's preparation

The invention relates to a special device for the purification of diesel exhaust gases, which device comprises, in the flow direction of the exhaust gas, an oxidation catalyst, a diesel particle filter with catalytically active coating, and, downstream of a device for introducing a reducing agent from an external reducing agent source, an SCR catalyst. The oxidation catalyst and the catalytically active coating of the diesel particle filter contain palladium and platinum. The ratio of the noble metals platinum and palladium in the overall system and on the individual components, oxidation catalyst and catalytically coated diesel particle filter, are coordinated with one another in such a way as to obtain firstly an optimum NO/NOratio in the exhaust gas upstream of the downstream SCR catalyst, and secondly optimum heating and HC conversion behaviour during an active particle filter regeneration.

Device for the purification of diesel exhaust gases

An oxygen storage material comprising cerium oxide and at least one second oxide of a metal Mis disclosed as well as a process for manufacturing the material and the use of this material in an exhaust gas cleaning catalyst. In a preferred embodiment the oxygen storage material comprises particles from a Ce/Mmixed oxide solid solution coated with an oxide of another metal M. Metal Me.g. can be calcium or zirconium while metal Mmost preferably is aluminum.

Oxygen storage material, process for its preparation and its application in a catalyst

An oxygen storage material based on cerium oxide with at least one other oxide of the metals silicon and zirconium, wherein the cerium oxide and the other oxides are present in the form of a mixed oxide. The material is obtainable in that hydroxidic precursors of the mixed oxide are first prepared in a manner known per se using a wet-chemical route, these precursors are optionally dried at temperatures between 80 and 300&#xb0; C. and the dried precursors are then treated under a hydrogen-containing atmosphere at a temperature between 600 and 900&#xb0; C. for a period of 1 to 10 hours. The reductive thermal treatment endows the material with a greatly improved dynamic behavior as compared with conventional calcination in air.

Oxygen storage material based on cerium oxide, a process for its preparation and its use

A starter catalyst for the purification of the exhaust gases from internal combustion engines, which include palladium on aluminum oxide and of barium oxide, as well as a process for its production. The barium oxide and palladium are together deposited in a finely divided state on the supporting material aluminum oxide and the average particle size of the palladium crystallites is between 3 and 7 nm. The small crystallite size of palladium and the barium oxide likewise deposited in finely divided state on the supporting material impart to the catalyst a high activity and long-term stability to high temperature stresses.

Exhaust-gas purification catalyst to be used close to the engine and process for its production

A process is provided for operating a three-way catalyst that contains an oxygen storage component, that has a minimum and a maximum filling degree for oxygen and that is located in the exhaust gas line of an internal combustion engine. The air/fuel mixture supplied to the engine is varied in such a way that the filling degree of the oxygen storage component in the catalyst is held within a set-point interval between the minimum and maximum filling degree. According to this process, in order to regulate the air/fuel mixture, migration of the filling degree out of the set-point interval is checked in a test phase in such a way that the filling degree is increased or lowered relative to the instantaneous value (initial value) by short-term enrichment or reduction in richness of the air/fuel mixture supplied to the engine by a certain amount and immediately returned to the initial value by a short-term opposing change in the air/fuel mixture (lean/rich pulse sequence or rich/lean pulse sequence). In the case of a breakthrough of lean or rich exhaust gas through the catalyst during the test phase, the air/fuel mixture is enriched or reduced in richness in order to correct the filling degree, wherein the amount by which the filling degree during the test phase is increased or decreased is such that no breakthrough of lean or rich exhaust gas takes place through the catalyst when the filling degree of the oxygen storage component is within the set-point interval.

Process for operating a three-way catalyst that contains an oxygen-storage component

A process for operating an exhaust gas treatment device in a gasoline engine which is operated mainly with a stoichiometric air/fuel ratio and is operated with a rich-mix air/fuel ratio when accelerating or under full load. The exhaust gas treatment device contains a three-way converter catalyst and a first lambda probe upstream of the catalyst and a second lambda probe downstream of the catalyst. The air/fuel ratio is controlled by using the signal from the first lambda probe, whereas the signal from the second lambda probe is used to check the first lambda probe (trim control) and to diagnose the function of the catalyst. Trim control with the second lambda probe is enabled only when, in the event of rich exhaust gas, the voltage difference between the probe voltage for the second lambda probe and a set point voltage is not larger than a predetermined value.

Process for operating an exhaust gas treatment device for a gasoline engine

An oxygen storing material with high thermal stability is disclosed which contains cerium oxide and at least one stabilizer from the group praseodymium oxide, lanthanum oxide, yttrium oxide and neodymium oxide, wherein the stabilizer(s) and optionally cerium oxide are present in highly dispersed form on the specific surface area of a high surface area support material from the group aluminum oxide, zirconium oxide, titanium oxide, silicon dioxide, cerium oxide and mixed oxides thereof and the oxygen storing material still has a specific surface area of more than 20, preferably more than 30 m /g, after calcination in air at 900&deg; C. for a period of 10 hours.

Oxygen storing material with high thermal stability and a process for preparation and use thereof

A single layer high performance catalyst containing on an inert carrier body a catalytic coating comprising platinum, rhodium and various oxide materials. The catalyst contains a catalytic coating having at least one first support material selected from the group having a first active alumina, a ceria rich ceria/zirconia mixed oxide and a zirconia component, said at least one first support material being catalyzed with a first part of the total platinum amount of the catalyst, and a second support material catalyzed with the second part of the total platinum amount and with rhodium said second support material being a second active alumina.

Single layer high performance catalyst

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 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.

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Offenbach, Germany

Lothar Mussmann