Electrochemical synthesis of hydrogen peroxide with a three‐dimensional rotating cylinder electrode

BACKGROUND This work analyzes the synthesis of H 2 O 2 from dilute NaOH solutions under 0.1 MPa O 2 using a batch reactor with a three‐dimensional rotating cylinder electrode. The centrifugal force produces a radial co‐current flow of the gas and liquid phases. Thus, good mass transfer conditions are achieved and the O 2 reduced to H 2 O 2 is easily replenished in the liquid phase.RESULTS Experiments with a glassy carbon rotating disc electrode identified 0.5 mol L ‐1 NaOH at 30°C as suitable operating conditions. Galvanostatic experiments with three‐dimensional rotating electrodes concluded that the best performance was obtained for a reticulated vitreous carbon structure of 100 ppi, at 40 mA cm ‐2 of macrokinetic current density and 1000 rpm rotation speed. Long‐term experiments showed 79% current efficiency and 8.2 kWh kg ‐1 specific energy consumption until 6 h of electrolysis, with 8.4 g L ‐1 H 2 O 2 concentration. However, the current efficiency decreases for longer electrolysis times and consequently the specific energy consumption is increased. Thus after 10 h electrolysis the concentrations were H 2 O 2 10.4 g L ‐1 and NaOH 1.41 mol L ‐1 .CONCLUSION A reactor having a three‐dimensional rotating cylinder electrode with co‐current oxygen and liquid flows inside the structure showed promising performance for H 2 O 2 production. © 2013 Society of Chemical Industry