SULFUR-DIOXIDE REMOVAL FROM FLUE-GASES BY ELECTROGENERATED AQUEOUS REDUCTANTS .1. OUTLINE OF THE COMPONENTS OF THE PROPOSED PROCESS

A novel indirect electrochemical reduction process is outlined in which aqueous absorbed SO2 species are reduced to elemental sulphur by electrogenerated aqueous reductants, such as Ti3+, V2+ of Cr2+ ions, which do not form metal sulphides in acidic aqueous solutions; hence, they may be regenerated electrochemically from their oxidised forms, after separation and recovery of the sulphur product. The generation of reductants in membrane-divided electrochemical reactors has been achieved with current efficiencies of > 90% and their oxidation by SO2 reduction has been found to produce sulphur yields of > 90% under optimal conditions. The implications for the specific energy requirement of the envisaged process is discussed.