Process of preparing alkali peroxide solutions

US5702585A · kind A · utility

Assignee

• Metallgesellschaft AG · DE

Inventors

• Eilhard Hillrichs · Büdingen, DE
• Manfred Kienberger · Pettenbach, AT
• Ulrich Sander · Rebstein, CH

Key dates

• Filing date: Nov 16, 1995
• Grant date: Dec 30, 1997
• Expiry date: Nov 16, 2015

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C25B15/08
• WIPO field: Surface technology, coating
• WIPO sector: Chemistry

Abstract

The process of making an aqueous alkaline solution containing alkali hydroxide and hydrogen peroxide and having an alkali hydroxide/H.sub.2 O.sub.2 molar ratio of 0.5 to 2.5 includes providing an electrochemical cell having a porous oxygen diffusion cathode, an anode and a cation exchange membrane separating an anode chamber containing the anode and a cathode chamber containing the cathode, providing a decomposition tank outside the electrochemical cell for receiving an aqueous starting solution containing at least one alkali sulfate, alkali hydrogen sulfate, alkali sulfite, alkali hydrogen sulfite, alkali carbonate and/or alkali hydrogen carbonate; feeding an alkali hydrogen sulfate-containing feed solution from the decomposition tank into the anode chamber, feeding an oxygen-containing gas to the cathode and feeding an alkali hydroxide-containing electrolyte into the cathode chamber; passing an electric current between the anode and the cathode to form alkali hydroxide and hydrogen peroxide at the cathode by cathodic reduction and to form sulfuric acid at the anode, withdrawing a sulfuric acid-containing solution from the anode chamber and feeding at least part of it into the dec…