Synthesis of CeAlO3/CeO2–Al2O3 for use as a solid oxide fuel cell functional anode material

A composite electrocatalyst was developed to be fitted for the purpose of satisfying the features required for use as a solid oxide fuel cell functional anode material. The main functionality searched for was the ability to make the direct oxidation of carbon containing fuels in an SOFC without being severely coked. The present paper deals with the synthesis and characterization of such material. Therefore, ceramic electrocatalysts composed of CeAlO3, CeO2 and Al2O3 were synthesized by the amorphous citrate method and calcined at temperatures ranging from 300 °C to 900 °C. The synthesis procedures were designed to produce nanometric sized powders for which the calcination conditions were selected in order to fulfill requirements such as ease to be sintered; formation of selected phases upon calcinations at different temperatures; particle size control; surface area and morphology well suited for the production of ceramic suspensions to be processed into an SOFC functional anode. The main results have shown that increasing the calcination temperature under an oxidizing atmosphere induces the CeAlO3 phase with a tetragonal perovskite type structure to undergo a phase transformation to CeO2 (and Al2O3) with cubic fluorite type structure. However, the structure is able to be reversed and reduced back to the CeAlO3 phase if calcined under a hydrogen atmosphere. The increase in the calcination temperature increases the particle average size, reduces the surface area and increases the material density, considering the same phase and crystalline structure. It was shown that the synthesis and calcinations procedures hinder the crystallographic identification of the presence of alumina.