Jong Pyo Kim

Preparation and Oxygen Permeability of ReBaCo2O5+δ (Re = Pr, Nd, Y) Ceramic Membranes

ReBaCo2O5+δ (Re=Pr, Nd, Y) oxides were synthesized by solid state reaction method. The oxygen permeation flux of ReBaCo2O5+δ (Re=Pr, Nd, Y) membranes increased with temperature and oxygen partial pressure and ranked as follow: PrBaCo2O5+δ > NdBaCo2O5+δ > YBaCo2O5+δ. The oxygen permeation response of PrBaCo2O5+δ membrane was fairly stable and no detectable degradation is observed at high temperature under carbon dioxide conditions (CO2 = 500 ppm).

Oxygen permeation performance of Ba0.5Sr0.5Co0.8Fe0.2O3−δ membrane after surface modification

The effect of minor surface modification on the performance of Ba0.5Sr0.5Co0.8Fe0.2O3−δ membrane was evaluated in the temperature region from 700 to 850 °C. Oxygen permeation experiments were conducted according to membrane thickness (1.0mm and 1.6 mm) and oxygen partial pressure (0.21, 0.42, and 0.63 atm) in the absence and in the presence of carbon dioxide (300 and 500 ppm). The oxygen permeation flux of Ba0.5Sr0.5Co0.8Fe0.2O3−δ membrane increased with increasing temperature and decreasing membrane thickness. The oxygen permeation flux through the membrane of 1.0 mm thickness with Ba0.5Sr0.5Co0.8Fe0.2O3−δ-modified surface was ca. 1.23 ml/cm2·min at 850 °C under air feeding condition. It was found that the Ba0.5Sr0.5Co0.8Fe0.2O3−δ-modified Ba0.5Sr0.5Co0.8Fe0.2O3−δ membrane has better oxygen permeation flux than the pristine Ba0.5Sr0.5Co0.8Fe0.2O3−δ membrane. In summary, it has been demonstrated that the surface morphology is an important factor in determining the oxygen permeation fluxes through Ba0.5Sr0.5Co0.8Fe0.2O3−δ membrane under mixed-control conditions.

Structural, Sintering and Electrical Properties of Cr-doped La0.6Sr0.4CrxFe1−xO3−δ (x=0.10, 0.20) Oxides

The perovskite Cr-doped La 0.6 Sr 0.4 Cr x Fe 1− x O 3− δ ( x =0.10, 0.20) oxides were synthesized via the citrate gel method. The perovskite forming of the La 0 6 Sr 0.4 Cr x Fe 1− x O 3− δ ( x =0.10, 0.20) oxides were studied by thermogravimetric analysis (TG), differential scanning calorimetry (DSC), and X-ray diffraction (XRD). Structural and chemical stability under H2-containing helium atmospheres of La 0.6 Sr 0.4 Cr x Fe x O 3− δ ( x =0.10, 0.20) were investigated by TG and XRD. The sintering microstructures of the perovskite La 0.6 Sr 0.4 Cr x Fe x O 3− δ ( x =0.10, 0.20) ceramics were investigated by scanning electron microscopy (SEM), and the electrical conductivities of both oxide ceramics were also measured up to 900 °C. The results demonstrated that the chemical stability of the Co-free La 0.6 Sr 0.4 Cr X Fe 1− X O 3− δ ( x =0.10, 0.20) oxides was significantly improved compared to the Co-containing La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3− δ and Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3−δ oxides. The incorporation of Cr cations in the B -site of the pervoskite oxides resulted in the improved structural and chemical stability of the as-synthesized La 0 6 Sr 0.4 Cr x Fe 1− X O 3− δ ( x =0.10, 0.20) oxides.