Effects of Al content on the oxygen permeability through dual-phase membrane 60Ce0.9Pr0.1O2--40Pr0.6Sr0.4Fe1-Al O3-

Abstract

graphic: ABSTRACT:Ceramic dual-phase oxygen transport membranes with the composition of 60wt.% Ce0.9Pr0.1O2-δ-40wt.%Pr0.6Sr0.4Fe1-xAlxO3-δ (x = 0.05, 0.1, 0.2, 0.3, 0.4, 0.6, 0.8, 1.0) (60CPO-40PSF1-xAxO) based on 60Ce0.9Pr0.1O2-δ-40Pr0.6Sr0.4FeO3-δ doped Al was successfully synthesized through a modified Pechini method. Crystal structure, surface microtopography and oxygen permeability are investigated systematically. The cell parameters of perovskite phase first increased and then decreased with the increase of Al content, which is related to the radius of the Al 3+ and the formation of impurity phase.As x ranges from 0.1 to 0.8, the oxygen permeability of the materials first increases and then decreases, and the maximum value of oxygen permeation rate for 60CPO-40PSF1-xAxO membranes with 0.4mm thickness at 1000 °C is 1.12 mL min -1 cm -2 when x = 0.4. XRD measurements revealed high temperature stability and CO2-tolerant property of the dual-phase composites. The partial replacement of Fe 3+ /Fe 4+ by Al 3+ causes the material not only to exhibit good stability, but also to increase the oxygen permeability of the membranes.

Effects of Bi Substitution on the Cobalt-Free 60wt.%Ce0.9Pr0.1O2−δ-40wt.%Pr0.6Sr0.4Fe1−xBixO3−δ Oxygen Transport Membranes

“…Figure 4 shows the EDXS images of the Bi-doped OTMs, which visualize the elemental distribution. All images exhibit a clear complementary elemental distribution in two phases, indicating the well formation of dual-phase OTMs [17,18,21,38]. Ce is mainly distributed in the fluorite phase, while Sr, Fe, and Bi are mainly distributed in the perovskite phase.…”

“…The oxygen permeability was measured by the gas chromatograph (GC, PANNA-A60, Changzhou, China), which could obtain concentrations of various gases in the sweep side. The oxygen permeation flux (Jo 2 ) included the leakage of oxygen and could be calculated with the following Equation ( 1) [18,37,38]:…”

“…In addition, Bi ion tends to exist as stable Bi 3+ , enhancing the stability of the system. Unlike iron ions with both bivalent and trivalent, where electrons can be rapidly conducted through the change in valence, the doping of Bi weakens the electronic conductivity, such as the results of doping with fixed valence elements such as Al [18,53]. Under He atmosphere, when x < 0.10, the enhancement of doping for oxygen permeability is stronger than the reduction brought by the weakening of electronic conductivity.…”

“…However, although the dual-phase OTMs exhibit enhanced stability, they usually have insufficient oxygen permeability [17]. Recently, our group has employed the stronger acidity (or weaker alkalinity, according to Lewis acid-base theory) or more stable transition metal elements to partially replace the original transition metal elements in B-site, and successfully developed a series of Fe-based cobalt-free dual-phase OTMs (e.g., Ce 0.85 Pr 0.1 Cu 0.05 O 2−δ -Pr 0.6 Sr 0.4 Fe 1−x Cu x O 3−δ , Ce 0.9 Pr 0.1 O 2−δ -Pr 0.6 Sr 0.4 Fe 1−x Al x O 3−δ ) [18][19][20], which show improvement of oxygen permeability and can retain the stability. Table 1 shows the oxygen permeation flux and stability test time of some related OTMs.…”

Synthesis and Characterization of 40 wt % Ce0.9Pr0.1O2–δ–60 wt % NdxSr1−xFe0.9Cu0.1O3−δ Dual-Phase Membranes for Efficient Oxygen Separation

“…The change from a fossil fuel-based to a renewable energy-based system requires the development of resource efficient materials with a long lifetime for energy conversion technologies. In this regard, mixed ionic-electronic conducting (MIEC) oxygen transport materials have drawn increasing interest due to their high potential for various energy conversion applications such as the oxygen transport membrane (OTM) for producing oxygen from air [1][2][3][4][5][6][7][8][9][10][11][12], electrolytes for batteries [13][14][15], cathode materials for solid oxide fuel cells [16][17][18], catalysts [19][20][21], and in membrane reactors [21][22][23]. With the current background of increases in CO 2 emissions and fossil resources depletion, CO 2 capture and utilization have been intensively researched to reduce CO 2 emissions, including thermolysis, membranes have received less attention in the literature for the oxygen transport process.…”