Electrosynthesis of H₂O₂ from O₂ in gas diffusion electrodes for the preparation of organic peracids and the complex of H₂O₂ with urea

Abstract

Electrosynthesis of hydrogen peroxide from oxygen was performed in a gas-diffusion carbon black electrode in aqueous solutions of various salts with alkali metal and ammonium cations with urea additions and without them at current densities of 0.1–0.15 A cm⁻². The resulting solutions containing 0.8–3.0 M H₂O₂ were concentrated to 25 M and dried with addition of urea to obtain the urea-H₂O₂ complex. The concentrated solutions of H₂O₂ were used to prepare peracetic and performic acids. Solid precipitates with up to 92 wt % urea perhydrate and up to 4 M peracid solutions were obtained. The presence of inorganic salts did not hinder the formation of these compounds. The presence of 1 M urea in solution had no adverse effect on the electrosynthesis of H₂O₂. These results indicate that the applications of electrosynthesis of H₂O₂ from O₂ in carbon black gas-diffusion electrodes can be significantly expanded for further use of the resulting solutions for the synthesis of various products.