Clean Metals Production by Solid Oxide Membrane Electrolysis Process

This paper reviews a clean metals, production technology that utilizes an oxygen-ion-conducting solid oxide membrane (SOM) to directly electrolyze metal oxides dissolved in a non-consumable molten salts. During the SOM electrolysis process, the desired metal such as magnesium, aluminum, silicon, or a rare earth is produced at the cathode while pure oxygen gas evolves at the anode. Compared with current state-of-the-art metal production processes, such as a chloride-based electrolysis process for magnesium production and the Hall–Héroult process for smelting aluminum, the SOM process brings various advantages such as simplified design, lower cost, lower energy use, and zero emissions. It provides a general route for producing various metals and has great potential to replace current metals, production processes. This paper examines the past and present progress of the SOM process, the challenges faced in commercialization, and the directions for future work.