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

Solubility of nickel oxide(NiO) in molten carbonates is one of the imp ortant factors determining MCFC's life. In this study, solubilities of NiO in the molten alkali carbonate (62mol%Li2CO3- 38mol%K2CO3) contai ning alkaline earth carbonates (SrCO3, BaCO3) have been measured under a P-CO2=0.3 atmosphere at 923K. And similarly, solubilities of NiO ap plying a constant potential in these molten carbonates have been measu red. The solubilies of NiO in the normal molten alkali carbonate (Li/K =62/38), containing BaCO3 and containing SrCO3 were 13.0x10(-6), 7.6x1 0(-6) and 2.6x10(-6) (mole fraction) respectively. The solubility of N iO was reduced by the addition of alkaline earth carbonates. The effec t of the solubility reduction was larger for SrCO3 than for BaCO3. The solubility of NiO with the applied constant potential (-100mY vs refe rence electrode((3/7=CO2/Air)/Au)) was smaller than without the potent ial except for the molten carbonate containing SrCO3.