Alkaline peroxide electrosynthesis by oxygen reduction using an acid anolyte in a divided reactor with a three‐dimensional rotating cylinder cathode and two‐phase flow induced by centrifugal force

BACKGROUND This work analyses the performance of a batch electrochemical reactor with a three‐dimensional rotating cylinder cathode for the synthesis of alkaline peroxide by reduction of O 2 under 0.1 MPa (abs). The centrifugal force produces a radial co‐current flow of the gas and liquid phases through the cathode achieving good mass‐transfer conditions for the O 2 reduction. RESULTS Galvanostatic experiments carried out during 2 h at 2 A (macrokinetic current density 398 A m −2 ), 30°C and 1000 rpm with 1 mol L −1 H 2 SO 4 as anolyte demonstrates that the cationic exchange membrane Nafion® 415 is an appropriate separator. However, a small decrease in the alkalinity of the cathodic compartment was observed. The use as anolyte of an equimolar solution of Na 2 SO 4 and H 2 SO 4 (1 mol L −1 ) maintains constant the total alkalinity of the cathodic solution. An experiment of 6 h yielded 10.3 g L −1 H 2 O 2 concentration with 62.3% current efficiency and 10.6 kWh kg −1 specific energy consumption, using Na 2 SiO 3 as addition agent. CONCLUSION A divided electrochemical reactor using an acid anolyte and a three‐dimensional rotating cylinder cathode with co‐current oxygen and liquid flows represents a simple strategy for localized generation of peroxide solutions with low total alkalinity. © 2014 Society of Chemical Industry