GB850567A - Improvements in the production of hydrogen peroxide - Google Patents

Abstract

<PICT:0850567/III/1> In a cyclic process for the production of hydrogen peroxide by the alternate, successive hydrogenation, oxidation and water extraction of a working solution of an alkylated anthraquinone, at least part of the hydrogenated working solution is cooled to precipitate crystals of the hydroquinone a portion of solution is removed therefrom, and the resulting crystal slurry together with any solution not subjected to cooling is subjected to oxidation. A solution containing say 4-24% wt. of an alkylated anthraquinone e.g. methyl-, ethyl-, propyl- or tertiary butyl-anthraquinone, mixtures thereof or mixtures with their tetrahydro derivatives, dissolved in an anthraquinone solvent e.g. diphenyl, anisole, benzene or toluene but preferably an alkylated naphthalene, either alone or in admixture with a hydroquinone solvent e.g. organic phosphate or phosphonate esters, aliphatic alcohols having 7-11 carbon atoms/molecule, or water immiscible ketones or ethers, is hydrogenated in A with gaseous hydrogen at 1-20 atmospheres and 25-60 DEG C. until the solubility limit of the hydroquinone formed is reached. The hydrogenated working solution is passed either wholly or in part to crystallizer B where it is cooled to 10-30 DEG C. below that temperature existing in the hydrogenator to precipitate crystals of the hydroquinone. A portion of the residual hydrogenated working solution is removed from the crystals in separator C e.g. a centrifuge, and the resulting slurry is passed to oxidiser D where together with any hydrogenated solution introduced direct from the hydrogenator A through line 13 it is oxidised by contact with air or other free oxygen containing gas. The proportion of residual hydrogenated working solution adhering to the crystals leaving the separator C, if the whole of the hydrogenated working solution is cooled, or the portion of solution passed direct to the oxidiser is controlled so that sufficient is present in the oxidiser to dissolve the regenerated p anthraquinone. Alternatively, when all the hydrogenated working solution is cooled, a portion of the residual solution separated in C may be fed through line 15 to the oxidiser to provide the required solution. The solution leaving the oxidiser passes to extractor E where hydrogen peroxide is isolated by water extraction, the denuded, regenerated working solution being recycled through line 11 to the hydrogenator, the remaining feed to which is delivered by line 10 as recycled hydrogenated working solution removed in separator C.