UBC Theses and Dissertations
Electroreduction of oxygen to hydrogen peroxide of particulate electrodes Oloman, Colin
The generation of hydrogen peroxide in dilute sodium hydroxide solutions was investigated by the electro-reduction of oxygen on beds of graphite particles. Two continuous electrochemical reactors were used to study the process at 16 to 20°C with oxygen pressures up to 12 atmospheres. The study embraced operation of the graphite cathode as both a fixed and a fluidised bed, though only the fixed bed was used at superatmospheric pressure. In each case both a two-phase system (cathode/oxygenated catholyte) and a three-phase system (cathode/catholyte/oxygen gas) were employed. The effects of the catholyte flow rate, catholyte pH, graphite particle size, bed depth, bed expansion, oxygen pressure, oxygen flow rate and the applied current on the process efficiency were measured. Depending on the conditions, the current efficiency for the conversion of oxygen to peroxide was between 20% and 100%, the yield of peroxide from oxygen was up to about 85% and the product peroxide concentration ranged from 0 to 0.15 molar. The results are interpreted in terms of the hydrodynamics and electrochemical kinetics in the cathode bed.
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