REGENERATION METHOD OF WORKING SOLUTION

A regeneration method of a working solution is herein disclosed in which various by-products which do not participate in the production of hydrogen peroxide and which are present in the working solution in a hydrogen peroxide production process utilizing an anthraquinone method can efficiently be converted into anthraquinones effective as reaction media for the production of hydrogen peroxide. The present invention is concerned with (1) a regeneration method of a working solution wherein at least a part of the unreduced working solution is brought into contact with a catalyst mainly comprising a y-alumina at a temperature of 40 to 150.degree.C, and (2) another regeneration method of a working solution wherein the working solution is brought into contact with a catalyst mainly comprising a y-alumina at a temperature of 20 to 150.degree.C under conditions that a concentration h (mol/liter) of the alkyltetrahydroanthra- hydroquinones in the working solution before the catalytic treatment meets the equation (0.0018xt-0.0285)xh~0.05 wherein t is a treatment temperature (.degree.C), to convert alkyltetrahydrooxyanthrones in the working solution into the alkyltetrahydroanthrahydroquinones.