GB686574A - Improvements in production of hydrogen peroxide and catalyst therefor - Google Patents

Abstract

Palladium supported on activated alumina is employed as a catalyst in the hydrogenation stage of a cyclic process for the production of hydrogen peroxide by reduction and oxidation of alkylated anthraquinones, particularly 2 tertiary butyl anthraquinone, preferably employing as a solvent a mixture of a prmary or secondary nonyl alcohol such as di-isobutyl carbinal or 3.5.5 trimethylhexanol-1, and a substituted naphthalene such as alpha methyl naphthalene. Other suitable intermediates referred to are 2 ethyl, 2 isopropyl, 2 sec. butyl, 2 sec. amyl and 1.3, 2.3, 1.4, or 2.7 dimethyl anthraquinones together with the corresponding tetrahydro-anthraquinones. The catalyst may be employed as a fixed bed which is regenerated in situ, or held in suspension in the working solution by mechanical agitation or by upflowing hydrogen, a mild agitation being preferable Spent catalyst is withdrawn and regenerated by treatment with an aqueous alkaline solution of an oxidizing agent, which may contain up to 50 per cent of a water miscible solvent to assist the solution of the oxidizing agent which may be alkali or alkaline earth metal chlorites or hypochlorites, organic hypochlorites, per compounds of general formula ROOH where R is hydrogen or a hydrogen radical. Alkali metal peroxides, perborates, carbonate or phosphate perhydrates, urea peroxide or organic peracids may also be used, the preferred oxidizing agents being sodium chlorite or hypochlorite, peracetic acid and tertiary butyl hydroperoxide. When hypochlorites are employed it is preferred to follow the reactivation with a hydrogen peroxide wash and a treatment with formaldehyde to ensure complete resolution of palladium oxide to the metal. The catalysts may be prepared by suspending the alumina in an aqueous acid solution of palladous chloride and adding formaldehyde and sodium bicarbonate successively, or by reducing chloropalladous acid with hydrogen, to give a palladium content of 0.1 to 2 per cent by weight. The efficiency of the catalyst in the process is compared with that of palladium supported on silica-alumina, activated coconut charcoal, active carbon prepared from coal or liquin, deodorizing carbon, corandum and silica gel. Specifications 465,070, 686,567 and 686,572 are referred to.