Evaporation of hydrogen peroxide with a microstructured falling film

A microstructured falling film evaporator made out of AlMg3 was used to evaporate a 50 wt.% aqueous hydrogen peroxide solution. Sufficient wetting with contact angles lower than 20° and a stable falling film was reached by a sealing procedure at elevated temperatures (about 100 °C). After a self-passivation procedure under operation conditions the relative decomposition related to the evaporated amount could be reduced to values of about 10%. From the experimental results it was concluded that the decomposition occurs mainly in the liquid phase during evaporation and not in the vapour phase by contacting the non-wetted surfaces of the evaporator and pipes. At an operation temperature of 130 °C 10 vol.% of hydrogen peroxide in the vapour could be reached which almost corresponds to the vapour/liquid equilibrium at the top of the evaporator.