GB817622A - Improvements in or relating to catalytic processes for preparing ketones from secondary alcohols - Google Patents

Abstract

The catalyst in a continuous vapour phase catalytic dehydrogenation process for the preparation of a ketone from a secondary alcohol is activated or regenerated by contacting it with the secondary alcohol in liquid state and containing at least one metal compound which will decompose to form a catalytically active deposit on the catalyst. Suitable catalysts may contain one or more metals such as copper, silver, chromium, manganese, nickel, tungsten, cobalt, iron, cadmium, uranium, tin and zinc, either as such or as the oxides or hydroxides. They may be supported on carriers such as kieselguhr, pumice, majolica or porcelain. The compound contained in the secondary alcohol during the activation is preferably a salt or salts (advantageously of an organic acid such as acetic acid) of one or more of the catalyst metals which will decompose to form a catalytically active compound, usually the oxide, of the metal(s) on the catalyst. The total amount of activating compound(s) may be between 1 and 10 pounds per ton of catalyst. The activation process is usually repeated during the operation of the plant, e.g. at periodic intervals of between 500 and 1000 hours. The activation may be effected by passing the liquid feed through the catalyst while gradually heating to reaction temperature (e.g. 300-500 DEG C.). The catalyst may be in a fixed bed or fluidized. In an example a catalyst comprising brass spelter previously pickled in mineral acid is activated by adding aqueous zinc acetate to the liquid feed during the warming-up stage and used for preparing acetone from isopropanol/water azeotrope.ALSO:The catalyst in a continuous vapour phase catalytic dehydrogenation process for the preparation of a ketone from a secondary alcohol is activated or regenerated by contacting it with the secondary alcohol in liquid state and containing at least one metal compound which will decompose to form a catalytically active deposit on the catalyst. Suitable catalysts may contain one or more metals such as copper, silver, chromium, manganese, nickel, tungsten, cobalt, iron, cadmium, uranium, tin and zinc, either as such or as the oxides or hydroxides. They may be supported on carriers such as kieselguhr, pumice, majolica or porcelain. The compound contained in the secondary alcohol during the activation is preferably a salt or salts (advantageously of an organic acid such as acetic acid) of one or more of the catalyst metals which will decompose to form a catalytically active compound, usually the oxide, of the metal(s) on the catalyst. The total amount of activating compound(s) may be between 1 and 10 pounds per ton of catalyst. The activation process is usually repeated during the operation of the plant, e.g. at periodic intervals of between 500 and 1000 hours. The activation may be effected by passing the liquid feed through the catalyst while gradually heating to reaction temperature (e.g. 300-500 DEG C.). The process is particularly suitable in the production of ketones from secondary alcohols containing up to about four carbon atoms. The alcohol may be anhydrous or admixed with water, e.g. as the azeotrope. The catalyst may be in a fixed bed or fluidized. In an example a catalyst comprising brass spelter previously pickled in mineral acid is activated by adding aqueous zinc acetate to the liquid feed during the warming-up stage and used for preparing acetone from isopropanol/water azeotrope.