HYDROGEN PEROXIDE PRODUCTION METHOD

PROBLEM TO BE SOLVED: To provide a hydrogen peroxide production method based on an anthraquinone method which enables safe and stable production of hydrogen peroxide with less impurities, e.g. phthalic acids for a long period without precipitation of anthrahydroquinones in tubes and filters.SOLUTION: A hydrogen peroxide production method comprises producing hydrogen peroxide by reducing and oxidizing alternately a working solution containing anthraquinones as a reaction medium. As anthraquinones in the working solution, a mixture of an anthraquinone having an alkyl substituent group and a tetrahydroanthraquinone having an alkyl substituent group in a mol ratio of 2:1 to 10:1 is used. In a reduction step, the ratio of the anthraquinone having an alkyl substituent group and the tetrahydroanthraquinone having an alkyl substituent group to all the anthraquinones in the working solution is 0.5-10 mol%, and the concentration of phthalic acids in hydrogen peroxide obtained can be reduced to 0.4 mg/HO-kg or lower.