Synthesis of LaAlO3 based materials for potential use as methane-fueled solid oxide fuel cell anodes

Lanthanum aluminate (LaAlO3) based oxides, with perovskite structure are promising for use as anodes for the oxidative coupling of methane in solid oxide fuel cells (SOFCs). This paper reports the synthesis and characterization of undoped, Sr-doped, Mn-doped and (Mn&Sr)-codoped LaAlO3 powders produced using the Pechini method. The synthesis was designed to produce powders that meet the requirements such as particle size control, high surface area, stoichiometric control and morphology suitable for the production of ceramic suspensions to be processed into an SOFC anode. The powders were analyzed using several physical and chemical characterization techniques such as XRD, XRF, TGA/DTA, SEM, TEM, BET, FTIR, XPS and H2-TPR. The results have shown that all the calcined samples studied exhibited single-phase perovskite structures possessing relatively high surface energy with nano-sized particles. Thermal analysis and FTIR results provided the basis for choosing 900 °C as the calcination temperature. Thermal expansion coefficients for the undoped and doped lanthanum aluminate matched very well that of the conventional yttria stabilized zirconia electrolyte. Among the different compositions studied, the Mn-doped, as well as the (Mn&Sr)-codoped electrocatalysts, exhibited a sufficiently high electrical conductivity for SOFC application, reaching values greater than 1 S/cm at the SOFC operation temperature.