Working up aqueous hydrogen peroxide solution from direct synthesis, useful e.g. in chemical synthesis, bleaching paper and pulp, sewage treatment or chemical polishing fluid, uses evaporator cascade with continuous evaporator at end

摘要

Process for working up aqueous hydrogen peroxide solution (I) from direct synthesis comprises: (a) removing hardly volatile inorganic impurities (II) by feeding (I) into an n-stage evaporator cascade, (where n is at least 2) and a continuous evaporator is used at least in the n-th stage, and thermal separation into steam containing H2O2 and a residue containing (II); and (b) concentration of the steam to increase the H2O2 content. An Independent claim is included for a process for producing (I) containing at most 0.001 wt.% (II) by: (i) reacting hydrogen and oxygen in aqueous medium in the presence of catalyst(s) and inorganic protonic acid(s); and (ii) working the reaction mixture up by the specified process.