Perovskite-type oxides for high-temperature oxygen separation membranes

Хартон, В.В.; Yaremchenko, A.A.; Kovalevsky, Andrei V.; Viskup, A.P.; Naumovich, E.N.; Kerko, P.F

doi:10.1016/s0376-7388(99)00172-6

Cited by 307 publications

(186 citation statements)

References 19 publications

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“…[5,11,18 -24]). The details on the measurements of steady-state oxygen permeation fluxes were also published earlier [5,11,21,22]. The permeation tests were carried out in the temperature range 1023 -1223 K. For all data on oxygen permeability presented in this paper, the membrane feed-side oxygen partial pressure ( p 2 ) was maintained at 21 kPa (atmospheric air).…”

Section: Methodsmentioning

confidence: 99%

Oxygen transport in Ce0.8Gd0.2O2−-based composite membranes

et al. 2003

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Gadolinia-doped ceria electrolyte Ce 0.8 Gd 0.2 O 2 À d (CGO) and perovskite-type mixed conductor La 0.8 Sr 0.2 Fe 0.8 Co 0.2 O 3 À d (LSFC), having compatible thermal expansion coefficients (TECs), were combined in dual-phase ceramic membranes for oxygen separation. Oxygen permeability of both LSFC and composite LSFC/CGO membranes at 970 -1220 K was found to be limited by the bulk ambipolar conductivity. LSFC exhibits a relatively low ionic conductivity and high activation energy for ionic transport ( f 200 kJ/mol) in comparison with doped ceria. As a result, oxygen permeation through LSFC/CGO composite membranes, containing similar volume fractions of the phases, is determined by the ionic transport in CGO. The permeation fluxes through LSFC/CGO and La 0.7 Sr 0.3 MnO 3 À d /Ce 0.8 Gd 0.2 O 2 À d (LSM/CGO) composites have comparable values. An increase in the p-type electronic conductivity of ceria in oxidizing conditions, which can be achieved by co-doping with variable-valence metal cations, such as Pr, leads to a greater permeability. The oxygen ionic conductivity of the composites consisting of CGO and perovskite oxides depends strongly of processing conditions, decreasing with interdiffusion of the phase components, particularly lanthanum and strontium cations from the perovskite into the CGO phase. D

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Section: Methodsmentioning

confidence: 99%

Oxygen transport in Ce0.8Gd0.2O2−-based composite membranes

et al. 2003

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“…The characterization of CaAl 0.5 Fe 0.5 O 2.5 ceramics included also scanning electron microscopy combined with energy dispersive spectroscopy (SEM/EDS), dilatometry, differential thermal and thermogravimetric analysis (DTA/TGA), and the measurements of total conductivity (four-probe DC) and steady-state oxygen permeability. The experimental procedures and equipment used for the characterization were reported elsewhere ( [6,[8][9][10][14][15][16] and references cited). All data on the oxygen permeation presented in this paper correspond to the membrane feed-side oxygen partial pressure (p 2 ) of 21 kPa (atmospheric air); the permeate-side oxygen pressure (p 1 ) varied from 0.8 to 20 kPa.…”

Section: Methodsmentioning

confidence: 99%

“…However, these phases exhibit a number of specific disadvantages, including thermodynamic and/or dimensional instability under high oxygen chemical potential gradients, very high thermal expansion coefficients (TECs), and reactivity with carbon dioxide and water vapor. One promising approach to enhance the materials stability refers to incorporation of stable Materials Research Bulletin 38 (2003) [773][774][775][776][777][778][779][780][781][782] trivalent cations, such as Ga or Al, into the iron sublattice of perovskite-like ferrites [4,[7][8][9]. This type of doping suppresses oxygen non-stoichiometry variations when the oxygen partial pressure or temperature changes; as a result, both thermal and chemically induced lattice expansion decreases [4,8].…”

Section: Introductionmentioning

confidence: 99%

Oxygen ionic conduction in brownmillerite CaAl0.5Fe0.5O2.5+

Хартон

Marozau

Vyshatko

et al. 2003

Materials Research Bulletin

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The oxygen permeability of CaAl 0.5 Fe 0.5 O 2.5þd brownmillerite membranes at 1123-1273 K was found to be limited by the bulk ionic conduction, with an activation energy of 170 kJ/mol. The ion transference numbers in air are in the range 2 Â 10 À3 to 5 Â 10 À3 . The analysis of structural parameters showed that the ionic transport in the CaAl 0.5 Fe 0.5 O 2.5þd lattice is essentially along the c axis. The largest ion-migration channels are found in the perovskite-type layers formed by iron-oxygen octahedra, though diffusion in tetrahedral layers of the brownmillerite structure is also possible. Heating up to 700-800 K in air leads to losses of hyperstoichiometric oxygen, accompanied with a drastic expansion and, probably, partial disordering of the CaAl 0.5 Fe 0.5 O 2.5þd lattice. The average thermal expansion coefficients of CaAl 0.5 Fe 0.5 O 2.5þd ceramics in air are 16:7 Â 10 À6 and 12:6 Â 10 À6 K À1 at 370-850 and 930-1300 K, respectively.

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“…However, to realize the process, the membrane is required possessing both high permeation flux and stability under syngas atmosphere. Among the developed materials, cobalt-doped Ln x (Ba,Sr,Ca) 1−x Co y Fe 1−y O 3−ı (Ln: rare earth metal, 0 ≤ x ≤ 1, 0 ≤ y ≤ 1) usually have high oxygen permeation fluxes but are unstable under reducing environments and long-term operation at high temperatures [11][12][13][14][15][16][17][18][19][20]. Ln x (Ba,Sr,Ca) 1−x Fe y (Zn,Al,Ga,Ti,Zr,Ce) 1−y O 3−ı (0 ≤ x ≤ 1, 0 ≤ y ≤ 1) usually possesses high stability under reducing environments but poor permeation fluxes [21][22][23][24][25][26][27][28][29][30][31].…”

Section: Introductionmentioning

confidence: 99%