Ultra-high oxygen permeable BaBiCoNb hollow fiber membranes and their stability under pure CH4 atmosphere

• Highest O2 flux of 14.1 ml cm−2 min−1 (950 °C) compared to reported values under He.
• Highly asymmetric morphology comprising a dense layer with a porous substrate.
• Membrane after a pure CH4 sweep was regenerated by short-time thermal treatment.

The ultra-high oxygen permeable BaBi0.05Co0.8Nb0.15O3−δ (BBCN) ceramic hollow fiber membranes have been fabricated with highly asymmetric morphology. The highest oxygen permeation flux achieved is 14.08 ml cm−2 min−1 at 950 °C with He as sweep gas. So far, this value is the highest permeation obtained under He sweep gas through hollow fiber membranes compare with all of the previously reported data under normal atmosphere oxygen partial pressure (~21 kPa) without any modification. The stability of membranes in CH4 is also investigated by oxygen permeation studies and further characterized by SEM, EDX, and XPS techniques. The results show that the oxygen flux decreases around 30% under CH4 as sweep gas for the 150 h duration. However, the oxygen permeation can be almost recovered by He as sweep gas in a short time. The degeneration is mainly due to the formation of barium carbonate on the membrane surface by the impact of CO2 which is produced from the combustion of methane.