Patent ID: 6676712
Filing Date: 2004-01-13
Classification: C01B

Abstract:
A process for the concentration of aqueous hydrogen peroxide of concentration cE (H2O2 starting material) in order to obtain hydrogen peroxide of concentration cP (H2O2 product), cP being equal to or greater than 90 wt. %, comprisingdiscontinuously crystallization, by arranging a cooling surface in a crystallizing vessel and wetting said surface at least partially with hydrogen peroxide having a concentration of at least 70 wt. %, cooling by a cooling medium located at a rear side of said surface, at a cooling rate of at least 1 K/s, from a temperature in the region of the melting point of the hydrogen peroxide used for wetting to a temperature at which seed crystals form in the wetting medium, filling the vessel with H2O2 starting material having a temperature below the melting point of the H2O2 seed crystals, lowering the temperature of the cooling medium to a value in the range from below the melting point of the H2O2 product to âˆ’50Â° C. and, starting from the seed crystals, allowing a crystal layer to grow during temperature reduction and, optionally, additionally after a desired temperature has been reached, removing uncrystallized hydrogen peroxide from the vessel and subjecting the crystal layer to a sweating operation in which the temperature of the cooling medium is increased in the course of from 0.2 to 20 hours to a value in the range from 10 K below to 5 K above the melting point of the H2O2 product, separating the hydrogen peroxide that is sweated out and obtaining crystalline hydrogen peroxide of concentration cP.