Multiplying Oxygen Permeability of a Ruddlesden-Popper Oxide by Orientation Control via Magnets

Ruddlesden-Popper-type oxides exhibit remarkable chemical stability in comparison to perovskite oxides. However, they display lower oxygen permeability. We present an approach to overcome this trade-off by leveraging the anisotropic properties of Nd2NiO4+delta. Its (a,b)-plane, having oxygen diffusion coefficient and surface exchange coefficient several orders of magnitude higher than its c-axis, can be aligned perpendicular to the gradient of oxygen partial pressure by a magnetic field (0.81 T). A stable and high oxygen flux of 1.40 mL min-1 cm-2 was achieved for at least 120 h at 1223 K by a textured asymmetric disk membrane with 1.0 mm thickness under the pure CO2 sweeping. Its excellent operational stability was also verified even at 1023 K in pure CO2. These findings highlight the significant enhancement in oxygen permeation membrane performance achievable by adjusting the grain orientation. Consequently, Nd2NiO4+delta emerges as a promising candidate for industrial applications in air separation, syngas production, and CO2 capture under harsh conditions. Ruddlesden-Popper oxide Nd2NiO4+delta particles can be aligned in a magnetic field generated by NdFeB magnets. A textured asymmetric membrane prepared in this way exhibited oxygen flux five times higher than a conventional membrane. In contrast to perovskite oxides, the material also showed excellent CO2-stability highlighted by an O2 flux of 1.4 mL min-1 cm-2 for 120 h at 1223 K under pure CO2 sweeping.image