A novel approach for the electrochemical oxidation of coal is described. The electrochemical cell employed an anode of coal or carbon particles dispersed in a molten carbonate electrolyte at 500°–800°C. At these temperatures, the oxidation kinetics of coal/carbon are sufficiently rapid that high current densities can be obtained at an inert working electrode. Results presented for various forms and concentrations of carbon include open‐circuit potentials, current‐voltage curves, and product gas evolution rates. At temperatures of 700°C and above, the measured potentials were in agreement with theoretical values of the C/CO2 redox couple. Product gas analysis indicated that complete oxidation of carbon to CO2 was achieved, thus providing the maximum electrochemical conversion efficiency (four electrons per carbon atom). By coupling this anode with an O2/CO2 cathode, fuel cell operation (i.e., electricity generation) should be feasible. The primary limitation observed in this study was the heavy chemical consumption of carbon by CO2 , which resulted in a low overall carbon conversion efficiency.

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The heats of formation at 298.15 K of Li3A105 and Li5A104 were found to be -420.22 and -561.61 kcal/mol, respectively, and the heat of disproportionation of Li3A103 to LÍ5AIO4 and LiA102 was found to be -0.66 kcal/mol.An equation allowing calculation of the thermodynamic parameters of -102 for a wide range of temperatures was developed. The enthalpy and entropy of the high-temperature form of LiAl608 were obtained. Using the Redlich-Kister equations, we calculated the phase diagram for the LiO0.5-AlOli5 system. The thermodynamics of the spinel phase and the stabilities of the a and ß forms of LiA102 as a function of pressure are discussed. Compounds of Lithium Oxide with Aluminum Oxide and Their Thermodynamic PropertiesLithium oxide is a strong base, and it forms a whole series of compounds with aluminum oxide, even though aluminum oxide is a weak acid. The best characterized compound is the one-to-one reaction product, LiA102. At least three different crystal structures, , ß, and 71,2 are known for LiA102, but it appears that only the y form is thermodynamically stable. There is a stable spinel structure on the alumina-rich side of the phase diagram3,4 which can be formulated as Li05Al25O4, although these crystals are stable over a substantial range of stoichiometry at high temperature.5,6 The compounds at the lithium-rich side of the phase diagram are naturally more highly basic and thus quite reactive, but at least two have been identifed and characterized, Li5A104 and Li3A103.7 The stoichiometry Li3A103 is nominally an o-aluminate, with all the hydrogen atoms of Al(OH)3 replaced with lithium, but it is not exceptionally stable. In fact Li3A103 disproportionates to LiA102 and LÍ5AIO4 on heating above 723 K.7 LiO0.5(s) + A10l5(c,7) = LiA102(s) AH70o = -15.02 kcal moT1 with only a slight variation with temperature. Combining this with the reactions of La Ginestra et al.7 gives LiA102(s) + 4LiOo,s(s) = Li5A104(s) AH = +8.27 kcal moT1 and LiA102(s) + 2LiO05(s) = Li3A103(s) AH = +6.77 kcal moT1We assume that ACP is zero for these reactions, so these AH values are valid at the temperatures of measurement and at 298.15 K. Thus we can calculate the heats of formation at 298.15 K as -420.22 kcal moT1 for Li3A103 and -561.61 for Li5A104. These values are significantly different from the heats of formation at higher temperatures given in the abstract of the experimental work7 primarily because the melting point of lithium comes below the experimental reaction temperatures.These values can be used to calculate the heat for the disproportionation of Li3A103 to Li5A104 and LiA102 ViLijAlOs = y8Li5A104 + y8LiA102 AH = -0.66 kcal moT1Since this reaction occurs when Li3A103 is heated,1 we know that if this reaction is exothermic, Li3A103 is