Patent GB-760605-A (GB)
Title: Purification of hydrogen peroxide and resulting hydrogen peroxide
IPC: C01B15/026
Filed: 1954-01-18
Abstract: Hydrogen peroxide is recovered from the crude reaction products produced by partial oxidation of an aliphatic secondary alcohol containing up to 6 carbon atoms in the molecule, by subjecting said product in a first step for a period of 5-100 minutes to a heat treatment at 75-120 DEG C. and distillation, during or after said heat treatment, to remove the secondary alcohol and carbonylic compound formed during the oxidation of the alcohol and produce a bottom fraction containing 5-35 per cent of hydrogen peroxide; in a second step for a period of 5-90 seconds to a heat treatment at 65-100 DEG C. and steam distillation, during or after said heat treatment, to produce a bottom fraction containing 5-35 per cent of hydrogen peroxide; and in a third step to distillation of the hydrogen peroxide and condensation thereof.  Water is added to the crude reaction product, if necessary, so that a bottom fraction containing 5-35 per cent, preferably 10-30 per cent of hydrogen peroxide is produced in the first step.  The first step is preferably carried out in a rectifying column at 85-110 DEG C. for 10-30 mins. A reboiler temperature of at least 75 DEG C. and preferably at least 90 DEG C. should be employed.  The pressure may be atmospheric or above or below atmospheric is 400-700 mm. of mercury.  Ketone distilled off in the first step may be reconverted to alcohol by hydrogenation, with or without separation from accompanying unconsumed alcohol, and recycled to the oxidation process.  The second step is preferably carried out by flowing the solution down a rectifying column in countercurrent to steam in a ratio of steam to feed of 0.4-5, more preferably 0.8-3.  Pressures of 200-700 mm. of mercury are suitable, 400-700 mm. being preferred.  The residence time is preferably 10-45 mins.  A small proportion of water, e.g. 0.05-0.6 of the feed to the column, is preferably introduced into the upper part of the column in order to scrub hydrogen peroxide from the vapours leaving the column.  The bottom fraction from the second step may be treated with an ion-exchange resin to remove metal impurities before being passed to the third step.  In the third step conditions are maintained such that further degradation of organic impurities is held to a minimum.  The pressure is preferably below 150 mm. of mercury, more preferably below 100 mm.  The residence time is preferably not greater than 4 mins.  A reflux ration (ratio of reflux to feed) of 0.1 may be employed. The impurities collecting in the evaporator may be purged continuously or intermittently at a rate equivalent to 5-25 per cent of the feed.  The solution being distilled in the third step may contain 50-85 per cent, preferably 65-85 per cent of hydrogen peroxide under reflux conditions.  The vaporous hydrogen peroxide may be passed to a column having an internal condenser and there fractionated under reduced pressure to yield a liquid fraction containing about 50 per cent of hydrogen peroxide and a vaporous fraction consisting essentially of water. The liquid may be further fractionated to yield a product containing at least 85 per cent of hydrogen peroxide in a second column similar to the first but also provided with a heating coil (columns G and H of Figs. 1 and 2 not shown), Hydrogen peroxide may be recovered from the bottom fraction by a further heat treatment at 60-170 DEG C. for 5-60 mins. in a tank or column and passing the heat treated liquid, except for a portion which is removed for the recovery of non-volatile impurities or vapours produced therefrom to the first or second step of the process.  The liquid may be passed down a column in countercurrent to steam and the vapours produced passed to the second stage of the process.  Specifications 708,339 and 731,238 are referred to.