Umicore Ag & Co Kg

Eidgenossische Technische Hochschule Zurich

Marek Maciejewski

Alfons Baiker

Thomas Kreuzer

Wendelin Jan Stark

Stefan Loher

Ulrich Goebel

Sotiris-Emmanuel Pratsinis

Meike Wittrock

Jan-Dierk Grunwaldt

Stephan Eckhoff

Wilfried Mueller

Ruediger Hoyer

Ina Grisstede

Maria Cristina Casapu

Aflons Baiker

Christina Maria Casapu

Stefan Fridolin Loher

Described is a method for the production of metal salts, wherein the cationic metal is preferably selected from Group I to IV metals and mixtures thereof and the anionic group is selected from phosphates, silicates, sulfates, carbonates, hydroxides, fluorides and mixtures thereof, and wherein said method comprises forming a mixture of at least one metal source that is a metal carboxylate with a mean carbon value per carboxylate group of at least 3 and at least one anion source into droplets and oxiding said droplets in a high temperature environment, preferably a flame. This method is especially suited for the production of calcium phosphate biomaterials such as hydroxyapatite (HAp,Ca10(PO4)6(OH)2) and tricalcium phosphate (TCP,Ca3(PO4)2) that exhibit excellent biocompatibility and osteoconductivity and therefore are widely used for reparation of bony or periodontal defects, coating of metallic implants and bone space fillers.

Flame synthesis of metal salt nanoparticles, in particular calcium and phosphate comprising nanoparticles

Nitrogen oxide storage catalysts are used to remove the nitrogen oxides present in the lean exhaust gas of lean-burn engines. As a result of the stress due to high temperatures in vehicle operation, they are subject to thermal aging processes which affect both the nitrogen oxide storage components and the noble metals present as catalytically active components. The present invention provides a process with which the catalytic activity of a nitrogen oxide storage catalyst which comprises, in addition to platinum as a catalytically active component, basic compounds of strontium and/or barium on a support material comprising cerium oxide, said catalytic activity being lost owing to the thermal aging process, can be at least partly restored. The two-stage process is based on the fact that strontium and/or barium compounds formed during the thermal aging with the support material, which also comprise platinum, are recycled to the catalytically active forms by controlled treatment with specific gas mixtures.

Dual-stage method for the reactivation of thermally aged nitrogen oxide storage catalysts

Described is a method for the production of metal salts, wherein the cationic metal is preferably selected from Group I to IV metals and mixtures thereof and the anionic group is selected from phosphates, silicates, sulfates, carbonates, hydroxides, fluorides and mixtures thereof, and wherein said method comprises forming a mixture of at least one metal source that is a metal carboxylate with a mean carbon value per carboxylate group of at least 3 and at least one anion source into droplets and oxiding said droplets in a high temperature environment, preferably a flame. This method is especially suited for the production of calcium phosphate biomaterials such as hydroxyapatite (HAp,Cal0(P04)6(OH)2) and tricalcium phosphate (TCP,Ca3(P04)2) that exhibit excellent biocompatibility and osteoconductivity and therefore are widely used for reparation of bony or periodontal defects, coating of metallic implants and bone space fillers.

Nitrogen oxide storage catalysts are used for removing the nitrogen oxides present in the lean-burn exhaust gas of lean-burn engines. Here, the purifying action is based on the nitrogen oxides being stored in the form of nitrates by the storage material of the storage catalyst during a lean-burn operating phase of the engine and the previously formed nitrates being decomposed in a subsequent rich-burn operating phase of the engine and the nitrogen oxides which are being liberated again being reacted with the reducing exhaust gas constituents over the storage catalyst to form nitrogen, carbon dioxide and water. Storage catalysts are thermally aged by high temperatures. The aging is due to sintering of the catalytically active noble metal components of the catalyst and to formation of compounds of the storage components with the support materials. According to the invention, the formation of compounds of the storage materials can be largely reversed by treatment of the storage material with a gas mixture comprising nitrogen dioxide and/or carbon dioxide and water vapor at temperatures of from 300 to 500&#xb0; C. The reactivation can be carried out either directly on the vehicle by setting appropriate exhaust gas conditions or during a routine service by removal of the catalyst from the vehicle and treatment with a gas mixture in an appropriate apparatus.

Method for the reactivation of thermally aged nitrogen oxide storage catalytic converters

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Zurich, Switzerland

Marek Maciejewski