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SOM (Solid-Oxide Oxygen-Ion-Conducting Membrane) Process
for Electrolysis of Metals and Alloys from their Oxides

(Funded by DOE, NSF, and Metal Oxygen Separations Technology)
Prof. Uday B. Pal and Dr. Peter Zink

Eric Gratz, Alex Roan, Jiapeng Xu, Wenjie Tu, Yihong Jiang, Xiaofei Guan, and Jarrod Millshtein


View a PDF presentation on Magnesium Production From Magnesium Oxide


The research
work demonstrates the technical viability of employing zirconia-based inert SOM anodes for environmentally sound and cost-effective production of metals such as magnesium, tantalum, titanium, rare earths, silicon, retc., by directly reducing them from their oxides. The inert anode consists of the oxygen-ion-conducting stabilized zirconia membrane in intimate contact on one side with a catalytically active electronic phase. The opposite (other) side of the zirconia membrane is placed in contact with an ionically conducting solvent phase containing the desired oxide for reduction. A cathode is placed in the solvent and an appropriate electric potential is applied between the electrodes to electrolyze the metals from their oxides.

The full-benefit of the process can be realized if it is conducted at temperatures between 1000-1400C. At these temperatures the ohmic resistance drop across the stabilized zirconia membrane are low and therefore high current densities on the order of 1 A/cm2 or greater can be obtained. In addition, the process efficiency can be further increased by directly reforming hydrocarbon fuel over the anode.

Topics covered in this research include: stability of the zirconia membrane in the selected molten solvent (flux), volatility of the flux, transport processes, potentiodynamic sweeps, electrolysis experiments, metal recovery and analysis and process scaleup.