GB811050A - Process for the production of highly concentrated hydrogen peroxide solutions - Google Patents

Abstract

Stable, pure, concentrated hydrogen peroxide is obtained by partially evaporating dilute solutions, preferably those containing 35-45 per cent by weight of hydrogen peroxide in a first stage, and conducting the vapour so obtained in countercurrent to a solution of substantially the same concentration as that of the initial solution in a dephlegmator, with drawing, the concentrated solution formed from the dephlegmator and evaporating it completely once in a separate heating tube and concentrating the vapours of this stage by fractionation in a rectifier column by regulating the cooling at the top of the column. The <PICT:0811050/III/1> heating tubes for the complete evaporation are preferably made of tantalum coated with a tantalum oxide layer. In a typical example a 35 per cent solution of hydrogen peroxide was adjusted to methyl orange neutrality with sodium pyrophosphate in a storage tank 11. Part of this solution was supplied through a pipe 12, to an evaporator 13, and another part by way of a pipe 14 to a dephlegmator 15. From the evaporator 13 the vapours pass into the dephlegmator 15 and excess water leaves by pipe 17. Concentrated hydrogen peroxide is withdrawn over an overflow sill at 19 and is supplied to a complete evaporator 111 which is treated by means of steam jacket 112. Vapours pass into a separator 113 where impurities are removed, and then enter the bottom of a rectifying column 114 which is fitted at the upper end with a reflux condenser 115. The condensate is drawn off through a cooled siphon 116 into storage tanks 117. Excess vapours are removed through a condenser 118 by a vacuum pump 119. Column 114 is preferably made of glass and loaded with glass rings; 10-12 litres per hour of 93-95 per cent hydrogen peroxide can be obtained from an apparatus having heating tubes with a length of 2 metres and an internal diameter of 20 mms.