Abstract

Dual-phase membranes based on oxygen-ion-conducting doped ceria and electron-conducting lanthanum chromite show appreciable oxygen flux and good chemical compatibility between the two phases. In this work, Sm_0.2Ce_0.8O_2−δ–La_0.7Ca_0.3CrO_3−δ (volume ratio 60:40) composite membranes with different grain sizes are prepared. Membranes with large grains (1–5 μm) show much higher permeability than those with small grains (~ 300 nm). Applying a surface coating of a Sm_0.2Ce_0.8O_2−δ–Sm_0.5Sr_0.5CoO_3−δ catalyst reduces the running-in time from 220 to several hours and improves the steady-state permeability. The performance of the composite membrane is maintained when applying pure CO₂ as sweep gas, showing promising potential in the application of these membranes in oxyfuel processes using CO₂-diluted oxygen.