SOLUBILITY OF NICKEL-OXIDE WITH AN APPLIED CONSTANT POTENTIAL IN MOLTEN ALKALI CARBONATES CONTAINING ALKALINE-EARTH CARBONATES

Solubility of nickel oxide(NiO) in molten carbonates is one of the important factors determining MCFC's life. In this study, solubilities of NiO in the molten alkali carbonate (62mol%Li2CO3- 38mol%K2CO3) containing alkaline earth carbonates (SrCO3, BaCO3) have been measured under a P-CO2=0.3 atmosphere at 923K. And similarly, solubilities of NiO applying a constant potential in these molten carbonates have been measured. The solubilies of NiO in the normal molten alkali carbonate (Li/K=62/38), containing BaCO3 and containing SrCO3 were 13.0x10(-6), 7.6x10(-6) and 2.6x10(-6) (mole fraction) respectively. The solubility of NiO was reduced by the addition of alkaline earth carbonates. The effect of the solubility reduction was larger for SrCO3 than for BaCO3. The solubility of NiO with the applied constant potential (-100mY vs reference electrode((3/7=CO2/Air)/Au)) was smaller than without the potential except for the molten carbonate containing SrCO3.