MgO STABILITY IN EUTECTIC Li₂CO₃–Na₂CO₃ AND Li₂CO₃–K₂CO₃

Research and technology studies on Molten Carbonate Fuel Cells (MCFC) are being directed at improving their performance in mode of greenhouse gas conversion for chemical energy storage. The changes in gas composition feeding MCFC demand new insulating materials to be found. In the current work, the equilibrium solubility of magnesia ceramics in air in contact with Li₂CO₃–Na₂CO₃ and Li₂CO₃–K₂CO₃ eutectic mixtures was measured at 600°С. The study shows that magnesia is completely stable in the tested melts for at least more than 270 h. Its solubility was found to increase in Li–K carbonate eutectic. Conclusions about the material stability are based on results of inductively coupled plasma atomic absorption spectroscopy of melts and scanning electron microscopy combined with X-ray diffraction employed to ceramics testing. Magnesia is recommended as an insulating material in electrolysis cells containing Li₂CO₃–Na₂CO₃ and Li₂CO₃–K₂CO₃ carbonate eutectics for the conversion of the greenhouse gas in chemical energy storage devices operating in air.