BaCe1-xZrxY0.15O3-d - Y/Gd -Doped CeO2 cer-cer composites for H2 separation

Hydrogen separation from syngas at high temperatures (>=600°C) is one of the most important H2-producing technologies and it has attracted wide interest in the last decades. Mixed ionic-electronic conductivity (MIEC) ceramic materials have received considerable attention due to their potential application as separation membranes in these kind of processes [1]. In MIEC membranes, the separation and transport of H2 occurs electrochemically in the form of protons and electrons. In a non-galvanic mode, the membrane must have both electronic and proton conductivities [2]. Y-doped BaCe1-xZrxO3-? (BCZY) perovskite oxides are promising candidates for the development of such membranes because they combine the high proton conductivity of barium cerates with the chemical stability of barium zirconates in CO2- containing atmospheres, such as syngas conditions [3]. However, the electronic conductivity exhibited by these materials may be not sufficient to work as H2 separation membranes. The performances of BCZY in this field can be improved by adding a second electronic conductor phase [2]. To this end, in this work, BaCe1-xZrxY0.15O3-? -Ce1-yMyO2-? (x=0.2, 0.3; y=0.15, 0.20; M=Y, Gd) cer-cer composites have been prepared and studied. Indeed, the addition of doped ceria should increase electronic conductivity in reducing atmospheres. The final purpose is to prepare symmetric dense membranes based on these cer-cer systems. The optimal composition, preparation and sintering conditions of the composites have been studied based on density, XRD, SEM and OM results. The chemical stability versus CO2 and the electrical conductivity of the composites is presently under investigation. H2 permeation tests on the dense membranes are programmed in the near future. [1] T. Norby, R. Hausgrud, Nonporous Inorganic Membranes, 2006, Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim. [2] J.W. Phair, S.P.S. Badwal, Ionics, 2006, 12, 103-115. [3] S. Barison Et al., J. Mater. Chem., 2010, 18, 5120- 512.