A novel CO2-resistant ceramic dual-phase hollow fiber membrane for oxygen separation

Robust oxygen permeable ceramic membranes have potential applications in clean energy industries like oxyfuel power plants and green chemical synthesis like syngas production combining the separation and reaction in one unit. The well-known and highly permeable perovskite oxide membranes are limited by their lower chemical stability. In this work, a novel dual-phase hollow fiber membrane based on a fluorite Pr0.1Gd0.1Ce0.8O2−δ(PCGO) and a spinel CoFe2O4(CFO) composite was developed via a phased inversion/sintering method. Enhanced oxygen permeability and unprecedented high CO2 resistance were realized by the 50 wt%PCGO-50 wt%CFO dual-phase hollow fiber membrane. The composite was synthesized via a one-pot sol-gel preparation method to achieve the homogenous distribution and the formation of percolative network of each phase for both oxygen ionic and electronic conduction purpose. The oxygen permeation flux of 0.54 mL min−1 cm−2 was achieved using He as sweep gas at 1000 °C. Membrane performance was further improved by coating a perovskite Ba0.5Sr0.5Co0.8Fe0.2O3−δ (BSCF) layer on the outside surface of the dual phase membrane to face the feed gas-air leaving the other membrane side untouched to maintain its high stability to withstand the harsh gas condition containing CO2. The dual phase membrane had been successfully operated at 950 °C in pure CO2 atmosphere for more than 200 h with flux rate fixed at 0.40 mL min−1 cm−2 without any noticeable performance degradation or membrane deterioration. By contrast, the flux rate of pure perovskite membrane had been sharply dropped down by 80% albeit operated for only 8 h.