GB872925A - Method of concentrating aqueous hydrogen peroxide solutions - Google Patents

Abstract

<PICT:0872925/III/1> An aqueous solution of hydrogen peroxide containing at least 8% by weight of hydrogen peroxide is concentrated by heating the solution under subatmospheric pressure to form a first mixture of hydrogen peroxide and water vapours, introducing said first mixture into an intermediate section of a liquid-gas contact zone under subatmospheric pressure, introducing into a lower section of said contact zone a second mixture of hydrogen peroxide and water vapour containing a higher proportion of hydrogen peroxide corresponding to the vapours in equilibrium with an aqueous hydrogen peroxide solution of at least 70% by weight of hydrogen peroxide under the prevailing temperature and pressure, and establishing intimate countercurrent contact between the two feeds so as selectively to strip water from said first mixture. In a preferred embodiment, dilute aqueous hydrogen peroxide of 40% concentration is fed to the system at point 1 and is mixed with hydrogen peroxide of 73.5% concentration. This mixture circulates through a vaporiser 2 to a separator 4 containing glass fibres which cause liquid to pass downwards and vapour containing 39.1% of hydrogen peroxide to traverse a line 9 to the middle of a column 10 packed with Raschig rings. At the foot of the column, a reboiler 13 causes an 88.83% solution of hydrogen peroxide to remain boiling and provide enough vapour for substantially hydrogen peroxide-free distillate to leave the head of the column at 14. At the same time 88.83% hydrogen peroxide is withdrawn at the foot of the column as product. The whole system is under reduced pressure.