GB798237A - Improvements in or relating to the production of hydrogen peroxide - Google Patents

Abstract

A degraded solution of an alkyl anthraquinone in a solvent, which has become degraded in the process for synthesizing hydrogen peroxide involving alternately hydrogenating the alkyl anthraquinone and oxygenating the resulting alky anthrahydroquinone which is recycled after separation of the simultaneously formed hydrogen peroxide, is regenerated by heating the degraded solution at at least 55 DEG C. in the presence of activated alumina or active magnesia. Activated alumina is microporous alumina of extensive surface area obtained by heating, e.g. at 300-800 DEG C., natural or synthetic hydrated alumina, which may or may not contain a minor proportion of silica, to convert it to a less-hydrated form, e.g. a -alumina monohydrate, or g -alumina. Active magnesia is anhydrous microporous magnesia of extensive surface area obtained by decomposing magnesium hydroxide, carbonate, or nitrate. The alumina or magnesia adsorbs the organic degradation products and catalyses the regeneration, and is preferably granular, e.g. 4-100 mesh. The adsorption may be effected at 55-300 DEG C., preferably 90-150 DEG C., and the adsorbent may be in amount at least 0.5 per cent, usually 5-10 per cent. The spent adsorbent may be revivified by extracting with an organic solvent. Preferred revivification is by successive treatments with heptane, methanol, hydrochloric acid solution in aqueous methanol, water, dilute aqueous alkali, e.g. 0.1N caustic soda, and water. The adsorbent is finally dried at 100-110 DEG C. Alkyl anthraquinones may be ethyl-, methyl-, propyl-, or isopropyl-anthraquinones, and solvents may be mixtures of benzene and higher alcohols, but exemplified is a solution of 2-t-butylanthraquinone in a mixture of 1-methyl naphthalene and diisobutyl carbinol. The alumina or magnesia contact may be batch or continuous in a column. It is preferred to treat continuously a portion, e.g. 10 per cent, of the recycle from the extractor to the hydrogenator. When the solvent contains both an alcohol constituent and a hydrocarbon constituent, the regeneration is effected on a solution from which the alcohol has been distilled, and the alcohol constituent is added after treatment. The activated alumina may have palladium deposited thereon. It is stated that silica gel, glass beads, corundum, magnesia obtained by burning magnesium in air, synthetic zeolite, and bone black are not effective in the regeneration.