The solubilization of O2reactant gas in mixtures of molten alkali carbonate, which are to be used as electrolytes in the Molten Carbonate Fuel Cells, has been investigated as a function of melt composition, temperature and O2-CO2gas atmosphere. The baseline content of dissolved oxygen in (52 + 48) mol% Li2CO3+ Na2CO3and (62 + 38) mol% Li2CO3+ K2CO3is markedly increased by the additions of 0.5 mol% rare-earth (RE = La and Gd) oxides to the melts. By a curve-fitting method the mechanisms through which oxygen dissolves into the melts are predicted. At 923 K the oxygen dissolution mechanism passes from a superoxide path, which is dominant in the additive-free melts, to either a prevalent peroxide path in the Li-Na melt or a mixture of superoxide and peroxide ions in the Li-K electrolyte. At lower temperature (873 K) RE oxide additives are effective in modifying the oxygen dissolution mechanism only for the Li-Na melts. © 2007 Elsevier B.V. All rights reserved.
All Science Journal Classification (ASJC) codes
- Physical and Theoretical Chemistry
- Atomic and Molecular Physics, and Optics