Julie Glasscock

Oxygen Permeation in Thin, Dense Ce0.9Gd0.1O1.95-δ Membranes II. Experimental Determination

Thin (~30 μm), dense Ce 0.9 Gd 0.1 O 1.95-δ (CGO10) membranes (5 × 5 cm 2 ) supported on a porous NiO/YSZ substrate were fabricated by tape casting, wet powder spraying and lamination. A La 0.58 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ /Ce 0.9 Gd 0.1 O 1 . 95-δ (LSCF/CGO10) composite cathode was applied by screen printing. Oxygen permeation measurements and electrochemical characterisation of the cells were performed as a function of temperature with air and varying hydrogen/steam mixtures flowing in the feed and permeate compartments, respectively. The oxygen flux was found to reach 10 N mL min -1 cm -2 at ~1100 K and to exceed 16 N mL min -1 cm -2 at 1175 K. The measured oxygen flux was in good agreement with theoretical predictions from a model that takes into account the bulk transport properties of Ce 0.8 Gd 0.1 O 1.95-δ , the anode and cathode polarisation resistances, and the gas conversion and gas diffusion losses in the permeate compartment. The performance of the membrane was also investigated under varying CH 4 and H 2 O gas mixtures at 1106 K. The oxygen flux increased with decreasing steam to carbon ratio and was found to exceed 10 N mL min -1 cm -2 of O 2 for steam to carbon ratios below 4:3. Post-test analysis of the tested membrane did not reveal any significant microstructural degradation of the CGO10 membrane or the anode-support.