GB1061447A - Dehydrogenation of cycloalkanols - Google Patents

Abstract

The gas phase dehydrogenation of cycloalkanols to cycloalkanones is conducted at elevated temperature in presence of a catalyst consisting of at least 80% of ZnO which has been obtained by precipitation from a Zn salt with a basic precipitant, and drying and annealing the ZnO, which has a surface of 5-20 m.2/g. The production of cyclohexanone from cyclohexanol is exemplified; other specified starting materials are 4-methylcyclohexanol, cyclooctanol and cyclododecanol.ALSO:ZnO, intended for use as a dehydrogenation catalyst, is prepared by precipitation from a Zn salt with a basic precipitant, dried and annealed to obtain a surface of 5-20 m2/g. The precipitate may be slowly heated to 400 DEG C. and annealed at between 400 DEG and 600 DEG C. until the desired surface is obtained. An after-treatment with H2 at 300-500 DEG is optional.ALSO:A dehydrogenation catalyst comprises ZnO which has been prepared by precipitation from a Zn salt with a basic precipitant, dried and annealed to obtain a surface of 5-20 m2/g. Ingredients which may be present in an amount of up to 20% are: pumice or other silicates, Cu compounds, alkali or alkaline earth metal salts of mineral acids and rare earth compounds; the Cu compounds may be e.g. oxide, hydroxide, carbonate or nitrate. The ZnO is preferably annealed at 400-600 DEG C. and may be treated with H2 at 300-500 DEG before use. A binding agent such as starch, graphite or stearic acid may be used in making the catalyst.