GB769514A - Improvements in or relating to the production of hydrogen peroxide - Google Patents

Abstract

<PICT:0769514/III/1> In the production of hydrogen peroxide by successive reduction and oxidation of an alkyl anthraquinone, a solution of an alkyl anthraquinone in an organic solvent is partially reduced with hydrogen in the presence of a particle form hydrogenation catalyst, the partially reduced solution is oxidzed with a free oxygen-bearing gas to produce hydrogen peroxide, the oxidzed solution is distilled in the presence of steam at 70-105 DEG C. under reduced pressure of 5-65 mm. Hg., so that substantially all the hydrogen peroxide and water are vaporized overhead and the bulk of the organic solvent is separated as bottoms fraction, and hydrogen peroxide is recovered from the overhead. The alkyl anthraquinone, e.g. 2 - methyl, 2 - isopropyl, 2 - tert - butyl, or 2 - ethyl anthraquinone, may be in solution in mixtures of benzene and cyclohexanol, or, preferably, mixtures of tetralin and cyclohexanol. Electrolytic hydrogen passes at 211 into absorber 212 filled with activated carbon and, thence, to reduction tower 214 where it contacts the anthraquinone solution recycled through 215. The reduction tower contained a, preferably, fixed bed of catalyst, e.g. Raney nickel, or palladium or platinum on alumina, and operates at 30-80 DEG C. to obtain 50-70 per cent conversion. The reduced solution passes through filter 216, and water-cooled heat-exchanger 218 to oxidizer 222, where it is contacted with air entering at 223. The oxidation may be as described in Specification 768,675 by concurrent or countercurrent contact at 30-80 DEG C. and 15-300 psia in a tower packed with inert solid. The oxidized solution is withdrawn at 225 through steam-heated heat-exchanger 226 to stripper 230, having steam coil 231, where it is contacted with steam entering at 249. The stripped solution withdrawn at 232 is recycled to the reduction tower through 215. Aqueous hydrogen peroxide containing solvent passes overhead to condenser-separator 235 and the separated solvent phase is returned as reflux to the stripper through 247, while the aqueous phase passes to centrifuge 238. Further separated solvent is returned from the centrifuge by 239 to oxidizer 222, and aqueous hydrogen peroxide passes to concentrator 241 heated by steam coil 242 and operated under reduced pressure e.g. 50 mm. Hg. Water and remaining solvent pass ovehead to condenser 244, whence part of the condensate is returned as reflux to the concentrator 241 and the remainder is passed to vaporizer 248, which vaporizes water for the steam supply to stripper 230. Hydrogen peroxide is withdrawn at 246. Any of the above pieces of equipment may be duplicated, particularly the absorber, reduction tower, and filter to permit regeneration of the absorbant and catalyst and cleaning.