GB805101A - Improvements in or relating to the preparation of hydrogen peroxide - Google Patents

Abstract

In the production of hydrogen peroxide by the successive catalytic hydrogenation and autoxidation of a quinone in solution in a solvent medium and extraction of the hydrogen peroxide generated with water the extraction step is carried out at a temperature below that of the hydrogenation step which may be 50-125 DEG F., and the solvent solution is heated after the extraction to the temperature of hydrogenation for the further production of hydrogen peroxide. The difference between the temperatures of hydrogenation and extraction is usually 5-25 DEG F. but may exceed 50 DEG F. The temperature of extraction is preferably below 100 DEG F., more preferably 50-80 DEG F. In the example the temperatures of hydrogenation, oxidation, and extraction are 95 DEG , 86 DEG and 80 DEG C. respectively. The solution may be treated with alumina, after extraction with water, to remove tar and water. Some water, e.g. 50-95 per cent of saturation, is preferably retained in the solution passing to the hydrogenation step. Quinones specified are 2-ethyl, 2-methyl, 2-n-propyl, 2-tert.-butyl anthraquinones and the corresponding tetrahydro anthraquinones. Solvents specified are mixtures of a primary or secondary alcohol, e.g. amyl alcohol, hexanol, cyclohexanol or diisobutyl carbinol and a hydrocarbon, e.g. benzene, xylene and a methyl naphthalene; and esters of cyclohexanol or an alkyl cyclohexanol with a monobasic acid, e.g. acetic, propionic or butyric acid. The esters may be used with or without other solvents, e.g. benzene, diethyl benzene or triethyl benzene. Catalysts specified are palladium or Raney nickel supported on active alumina, silica, or carbon.