Abstract: The present invention relates to a process for preparing molybdenum-bismuth-iron-cobalt-based multielement oxide catalysts by means of hydrothermal synthesis, wherein the hydrothermal synthesis is conducted with an aqueous solution and/or an aqueous suspension of precursor compounds of the elements present in the multielement oxide catalyst to be prepared, the pH of which has been adjusted to a value between about 6 and about 8. The present invention also further relates to the multielement oxide catalysts obtainable by this process and to the use thereof in the partial gas phase oxidation of olefins and tert-butanol.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: Process for the preferential oxidation of carbon monoxide and/or CH3OH in a hydrogen containing process stream by contacting the process stream with a catalyst comprising gold on a support comprising non-reducible magnesium aluminium oxide in form of MgAl2O4 spinel.

Abstract: Process for the preferential oxidation of carbon monoxide and/or CH3OH in a hydrogen containing process stream by contacting the process stream with a catalyst comprising gold on a support comprising non-reducible magnesium aluminium oxide in form of MgAl2O4 spinel.