Platinum Metals Rev., 1963, 7, (4), 146
Platinum in Hydrogen Peroxide Production
An Improved Electrolytic Process
The production of hydrogen peroxide on a very large scale is generally considered to be most economically carried out by the oxidation/reduction of anthraquinone. Smaller scale manufacture, however, is still by the older electrochemical processes which make use of the exceptionally high resistance of platinum to anodic oxidation.
Dr Joseph Miiller, of Degussa, Rhein-felden/Baden, has recently described modifications to the Weissensteiner process—originally developed in 1905—which have resulted in substantial reductions in current consumption and space requirements. It is now believed to be the most economical of the electrochemical processes in operation (Chemie-Ing. Techn., 1963, 35, (5), 389-392).
Pure sulphuric acid is electrolysed using high anodic current densities to form persulphuric acid, which on hydrolysis forms hydrogen peroxide. The latter is distilled off. The anodes consist of silver wires sheathed with platinum 60 to 85 microns thick. Later modifications of these anodes employed a platinum wire 0.12 mm diameter, 10 metres long, welded on to a tantalum sheath 150 microns thick enclosing a 1.2 mm diameter silver wire. The silver core provides high conductivity for the electrode to enable a uniform potential to be used along its entire length. The tantalum sheath protects the silver core from attack by sulphuric acid and the platinum wire carries the current into the solution to be electrolysed.
Each anode operates at the centre of a narrow-bore tube of porous porcelain which acts as a diaphragm to separate the anode and cathode reactions. Most of the cells in operation have had lives exceeding ten years.