Electrolysis of iron with oxygen gas evolution from molten sodium borate electrolytes

Abstract

Molten oxide electrolysis can be used to reduce the carbon dioxide emissions from ironmaking. In this paper, we electrochemically decompose iron oxide (Fe2O3) into iron (Fe) and oxygen (O-2) using boron trioxide and sodium oxide (B2O3-Na2O) as the molten oxide electrolyte at 1000 degrees C that is less than the temperature of other molten oxide electrolysis. The formation of Fe at the cathode and O-2 at the anode is identified by analysing products from both electrodes. The results suggest that the cathodic current efficiency of electrolysis at 2 V is about 54.7%, energy consumption is about 5.27 kW h kg(-1) of Fe at 2 V electrolysis, and purity of the reduced Fe was more than 97 mol.%. With respect to the process temperature and product yield, B2O3-Na2O molten oxide has potential as a supporting electrolyte to reduce Fe2O3 to Fe without consuming any carbon.