Patent ID: 7048905

Claim:
A process for the production of concentrated aqueous solutions of hydrogen peroxide by direct synthesis starting from H 2 and O 2 , comprising: (a) feeding to a reactor containing a heterogeneous catalyst based on palladium and platinum and supported on activated carbon, wherein the catalyst is present as a dispersion in a liquid reaction medium: (i) a liquid stream comprising an alcohol or a mixture of C 1 –C 3 alcohols or a mixture of said alcohols with water, containing at least 50% by weight of alcohol, also containing an acid promoter and a halogenated promoter, the alcohol and optionally all or part of the water contained in the stream, being recycled from the subsequent phase d); (ii) a gaseous stream containing hydrogen, oxygen and an inert gas, wherein the concentration of the hydrogen in the gaseous stream is less than 4.5% by volume and the concentration of the oxygen in the gaseous stream is less than 21% by volume, and the balance is an inert gas; (b) removing from the reactor: (iii) a liquid stream consisting of stream (i) and also containing the hydrogen peroxide and water produced by the reaction, wherein the concentration of hydrogen peroxide is from 2% to 10% by weight; and (iv) a gaseous stream consisting essentially of non-reacted hydrogen and oxygen and the inert gas, (c) optionally adding to (iii) water in such a quantity so that its content is at least equal to that of the final aqueous solution of hydrogen peroxide; (d) sending the stream deriving from (c) to a distillation system from which the following are removed; (v) one or more streams containing all the alcohol and optionally water, which are recycled to (a), (vi) a concentrated aqueous solution, as defined above, of H 2 O 2 with a titer ranging from 15 to 60% by weight, (vii) optionally a stream containing the water fed in excess in (c).