Chemical Environment-Induced Mixed Conductivity of Titanate as a Highly Stable Oxygen Transport Membrane

Coupling of two oxygen-involved reactions at the opposite sides of an oxygen transport membrane (OTM) has demonstrated great potential for process intensification. However, the current cobalt- or iron-containing OTMs suffer from poor reduction tolerance, which are incompetent for membrane reactor working in low oxygen partial pressure (pO₂). Here, we report for the first time a both Co- and Fe-free SrMg_0.15Zr_0.05Ti_0.8O_3-δ (SMZ-Ti) membrane that exhibits both superior reduction tolerance for 100 h in 20 vol.% H₂/Ar and environment-induced mixed conductivity due to the modest reduction of Ti4+ to Ti3+ in low pO₂. We further demonstrate that SMZ-Ti is ideally suited for membrane reactor where water splitting is coupled with methane reforming at the opposite sides to simultaneously obtain hydrogen and synthesis gas. These results extend the scope of mixed conducting materials to include titanates and open up new avenues for the design of chemically stable membrane materials for high-performance membrane reactors.