GB759464A - A process for the preparation of hydrogen peroxide - Google Patents

Abstract

In the production of hydrogen peroxide by the interaction in the gaseous phase of a primary or secondary alcohol and and oxygen, the oxygen as such or in the form of air is injected into a continuous steam of the alcohol in the gaseous state at a plurality of points along the gas stream, the pressure throughout the reaction being maintained at 3-70 atmos. absolute, the quantity of alcohol being in excess of the stoichiometric requirements throughout the reaction, and unreacted oxygen being continually present throughout the reaction. The overall ratio of alcohol to oxygen should preferably be 2:1-20:1, more preferably 5:1-10:1. The amount of oxygen added in each zone is preferably 0.25-0.01 mole, more preferably 0.1-0.04 mole per mole of alcohol in the zone. The same proportion of oxygen is preferably added in each zone. The residdence time of the alcohol is preferably progressively less from zone to zone in the direction of flow. The total residence time may be 1-60 sec. Not more than 90 per cent of the oxygen fed to the process is preferably reacted, in order to ensure the presence of unreacted oxygen in the alcohol throughout the reaction. The residual amount of alcohol in each zone is preferably maintained at 10-500 moles per mole of oxygen. The oxidation may be carired out in the presence of an inert diluent gas, e.g. steam, nitrogen or helium, which may be introduced together with the alcohol or oxygen. The gaseous alcohol may be obtained by the vaporization of an aqueous azestrope, e.g. of isopropanel. Other alcohols specified are ethanol, n-propanol, n-butanol, iso-butanol, ethylene glycol, sec-butyl alcohol, sec-amyl alcohol, cyclohexanol, allyl alcohol, and proargyl alcohol. The reaction may be carried out in a single tube having oxygen inlets at intervals along its length (Fig. 1, not shown) or in a plurality of connected tubes arranged in series into each of which oxygen is injected (Fig. 2, not shown). The reaction tube or tubes may be heated by a fluid heat exchange medium or electrically. Where a plurality of tubes is employed, each tube may be heated independently and each zone may be maintained at a different temperature. Spherical instead of tubular vessels may be employed. The vessels may be constructed of glass, stainless steel, porcelain, aluminium, tin or resin. The gaseous product may be condensed, and then distilled in the presence of water under reduced pressure. Unconsumed alcohol together with alcohol produced by hydrogenation of carbonylic by-products may be recycled.