Oxygen Permeation through U-Shaped K₂NiF₄-Type Oxide Hollow-Fiber Membranes

Abstract

The first oxygen permeation data for a dense hollow-fiber membrane based on a K 2 NiF 4 -type oxide are reported. The U-shaped (Pr 0.9 La 0.1 ) 2 (Ni 0.74 Cu 0.21 Ga 0.05 )O 4+δ (PLNCG) hollow-fiber membranes were prepared by a phase-inversion spinning process. The dependences of the oxygen permeation on the feed air flow rate, sweep helium flow rate, oxygen partial pressure on the shell side, and operating temperature were experimentally investigated. The effects of the bulk diffusion and the surface exchange on the oxygen permeation flux through the U-shaped PLNCG hollow-fiber membranes are also discussed. During around 320 h of operation, a steady oxygen permeation flux of 1.0 mL/(min 3 cm 2 ) was obtained at 975 °C under conditions of an air feed flow rate of 180 mL/min and a helium sweep flow rate of 55 mL/min. XRD and SEM analyses of the spent hollow-fiber membrane showed the good stability of the U-shaped PLNCG hollow-fiber membranes.

Highly Stable Dual‐Phase Membrane Based on Ce0.9Gd0.1O2–δ—La2NiO4+δ for Oxygen Permeation under Pure CO2 Atmosphere

“…To change the driving force (oxygen concentration gradient between the two membrane sides), the oxygen partial pressure can be increased or decreased in the feed side or sweep the side, respectively. The latter mode is more conveniently operated in a laboratory just by adjusting the sweep gas flow rates as reported in earlier studies …”

“…To further investigate the effects of sintering on the membrane microstructures and oxygen permeation behavior, the apparent activation energy was calculated from the various flux values at different operation temperatures by applying the Arrhenius plot (Figure b and S7, Supporting Information) . Comparing the average activation energy of M1400 (79.1 ± 1.5 kJ mol –1 ) with that of M1350 (112.0 ± 4.3 kJ mol –1 ), it can be observed that the former has a rather lower apparent activation energy, resulting from the difference in the sintering temperature.…”

“…The latter mode is more conveniently operated in a laboratory just by adjusting the sweep gas flow rates as reported in earlier studies. [50][51][52] The oxygen permeation fluxes of 40GDC-60LNO hollow fibers sintered at 1400 C (M1400) as functions of the helium sweep gas flow rate between 750 and 950 C are shown in Figure 4a. The temperature rise led to an increase in oxygen fluxes.…”

A novel heterogeneous La0.8Sr0.2CoO3−δ/(La0.5Sr0.5)2CoO4+δ dual‐phase membrane for oxygen separation

“…Mixed ionic‐electronic conductors (MIECs) exhibit simultaneously high ionic and electronic conductivities. Perovskite and Ruddlesden–Popper oxide‐based MIECs in particular are among the best materials for oxygen separation membrane . Perovskite oxide provides isotropic oxygen ionic transport pathway given its cubic structure whereas Ruddlesden–Popper oxide exhibits anisotropic oxygen ionic transport pathway that favors transport in a certain direction.…”

“…Oxygen transport through the dense membranes made of these oxides normally occurs via oxygen ionic diffusion driven by the oxygen partial pressure gradient at high temperature (above 700°C) so that the passages of all other gas molecules are not allowed; thus giving them absolute oxygen selectivity. Previous studies have revealed that both perovskite and Ruddlesden–Popper oxides exhibit high oxygen permeability and structure stability …”