Isothermal Pressure-Swing Cycling of Strontium Doped Lanthanum Manganite Oxides for Fuel Production
In principle, fuel production capacity can be determined, a priori, from knowledge of the thermodynamic properties of a non-stoichiometric oxide. Accordingly, as a first step, the thermodynamics of various compositions of lanthanum strontium manganite oxides (LaxSr1-xMnO3) were modeled at high temperature from literature data . The theoretical, equilibrium fuel production capacity at 1500°C is found, on the basis of this analysis, to exceed that of undoped ceria, by almost a factor of two (and more than a factor of three at 1400°C). Motivated by this result, samples of x = 0.1, 0.2, 0.3 and 0.4 were synthesized via solid state reaction and then experimentally evaluated for fuel productivity using in an in-house constructed thermochemical reactor. Cycling between Ar (with 10 ppm oxygen) and 20% steam (balance Ar) at 1500°C shows that indeed the series of materials offer higher fuel production capacity under conditions of long-cycle times. In addition, oxygen release rates are higher for the perovskites than they are for ceria, indicating that more fuel is produced for a given cycle with finite periods.
 Y. Hao, C.-K. Yang and S. M. Haile, Phys. Chem. Chem. Phys., 2013, 15, 17084–17092.
 J. Misuzaki, et al. Solid State Ionics, 2000, 132, 167–180