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AssigneeHoechst Aktiengesellschaft
InventorsSiegfried Rebsdat, Sigmund Mayer, Josef Alfranseder, Josef Riedl
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The activity of supported silver catalysts used up in the direct oxidation of ethylene with molecular oxygen or air is improved by impregnating the catalyst arranged in a fixed bed with a solution of a caesium and/or rubidium compound in an inert organic solvent, optionally together with up to 40% by weight of water, calculated on the total liquid, as dissolving intermediary, so as to produce a concentration gradient of from 0.3 to 20 parts of caesium and/or rubidium per 1 million parts of catalyst and per meter of fixed bed, counter to the direction of flow of the gas to be reacted. In this manner the activity of the catalyst is considerably improved which results in an increased selectivity of the oxidation of ethylene to ethylene oxide.
Process for improving the activity of supported silver catalysts for the direct oxidation of ethylene with molecular oxygen or air, the catalyst being arranged as a fixed bed, by applying an average caesium and/or rubidium content of 20 to 1.000 parts per 1 million parts of catalyst to the catalyst, which has already been used for the direct oxidation, with an impregnating liquid which contains caesium compounds and/or rubidium compounds, wherein the application is carried out so that a concentration gradient from 0.5 to 20 parts of caesium and/or rubidium per 1 million parts of catalyst per meter of fixed bed is produced, so that the concentration gradient increases in the direction of flow of the gases to be reacted.
Dependencies are inferred from the claim text.