Stability and oxygen permeation behavior of Ce0.8Sm0.2O2−δ–La0.8Sr0.2CrO3−δ composite membrane under large oxygen partial pressure gradients

The stability and oxygen permeation behavior of the Ce0.8Sm0.2O2−δ–La0.8Sr0.2CrO3−δ dual-phase composite were investigated under a large oxygen gradient with one side of it exposed to air and the other side to CO, CH4 or H2 at elevated temperatures. An oxygen permeation flux of 8.6 × 10−7 mol cm−2 s−1 was obtained with a 1.1 mm thick membrane tube under air/CO gradient at 950 °C, and no decrease in the flux was observed within a period of 110 h. The oxygen flux under air/CO gradient was found to be about twice that under air/CH4 or air/H2 gradients, which may be attributed to the higher catalytic activity of the membrane towards the oxidation of CO. The membrane tube remained intact after high temperature operation for over 1000 h, and no significant change in the phase composition and microstructure occurred. The dual-phase composite may satisfy the stability requirement under the stringent membrane reactor conditions.