Oxygen permeation modelling of perovskites

Hassel, B.A. van; Kawada, Tatsuya; Sakai, Natsuko; Yokokawa, Harumi; Dokiya, Masayuki; Bouwmeester, Henny J.M.

doi:10.1016/0167-2738(93)90419-4

Cited by 143 publications

(73 citation statements)

References 18 publications

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“…Depending on the simplification applied to the Nernst-Einstein relation for the ionic conductivity, different empirical correlations for bulk diffusion have been proposed [42,[46][47][48][49]. Due to the high electronic conductivity of mixed-conducting ceramic membranes, the concentration of electrons is maintained constant across the ITM at steady state.…”

Section: Bulk Diffusionmentioning

confidence: 99%

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Numerical simulation of ion transport membrane reactors: Oxygen permeation and transport and fuel conversion

Hong

Kirchen

Ghoniem

2012

Journal of Membrane Science

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Ion transport membrane (ITM) based reactors have been suggested as a novel technology for several applications including fuel reforming and oxy-fuel combustion, which integrates air separation and fuel conversion while reducing complexity and the associated energy penalty. To utilize this technology more effectively, it is necessary to develop a better understanding of the fundamental processes of oxygen transport and fuel conversion in the immediate vicinity of the membrane. In this paper, a numerical model that spatially resolves the gas flow, transport and reactions is presented. The model incorporates detailed gas phase chemistry and transport. The model is used to express the oxygen permeation flux in terms of the oxygen concentrations at the membrane surface given data on the bulk concentration, which is necessary for cases when mass transfer limitations on the permeate side are important and for reactive flow modeling. The simulation results show the dependence of oxygen transport and fuel conversion on the geometry and flow parameters including the membrane temperature, feed and sweep gas flow, oxygen concentration in the feed and fuel concentration in the sweep gas.

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Section: Bulk Diffusionmentioning

confidence: 99%

“…Although a multistep kinetic mechanism written in terms of more elementary reactions exist [39,40], the expression (1) is sufficient to model the overall surface exchange process on both sides of the membrane [41,42].…”

Section: Surface Exchangementioning

confidence: 99%

Numerical simulation of ion transport membrane reactors: Oxygen permeation and transport and fuel conversion

Hong

Kirchen

Ghoniem

2012

Journal of Membrane Science

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“…Although charge disproportionation was not observed in LaCoO 3 by XAS [3], Sarma et al [4] state that for this material the influence of both types of charge fluctuation is of the same order of magnitude, leading to a very mixed character of the ground state. Charge disproportionation was used to model oxygen nonstoichiometry [6] and Seebeck data [7] of La 12x Sr x CoO 32d . In both cases, however, the best fit implied the simultaneous presence of unrealistically high concentrations of Co 21 and Co 41 .…”

mentioning

confidence: 99%

Use of the Rigid Band Formalism to Interpret the Relationship between O Chemical Potential and Electron Concentration inLa1−xSrx
Lankhorst
¹
,
Bouwmeester
²
,
Verweij
³

1996
Phys. Rev. Lett.
93
9
56
0
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The equilibrium oxygen chemical potential of mixed oxygen ion and electron conducting perovskites La 12x Sr x CoO 32d was measured as a function of d and x by high temperature oxygen coulometric titration. An almost linear decrease in the chemical potential is observed with increasing net electron concentration. The observed behavior is interpreted to reflect the corresponding change in the Fermi level upon gradually filling up states in a broad electron band with electrons induced by vacancy formation and Sr doping. Assuming a rigid band formalism, an apparent density of states at the Fermi level was calculated, the value of which is in good agreement with that obtained from XPS.[ S0031-9007(96) PACS numbers: 71.20. Eh, 61.72.Ji, 66.30.Fq Many of the 3d transition metal perovskite-type oxides are characterized by increased lattice oxygen vacancy formation at high temperatures, which results in substantial departure from oxygen stoichiometry. Vacancy formation is accompanied by a proportional change in the average valency of either the transition metal or oxygen ions. The relatively high vacancy mobility in conjunction with the metalliclike electronic conductivity causes these materials to be permeable for oxygen gas [1], which is of interest for various applications. In addition, many of the 3d transition metal perovskites are studied for special electronic and magnetic transitions which may occur either as a function of temperature or composition [2][3][4]. In the ZSA theory [5], the electronic structure of these oxides is interpreted in terms of the competition between charge disproportionation of the Mott Hubbart type,L, where d n denotes the n-electron 3d state of the transition metal and L denotes a hole in the wide anion valence band. Although charge disproportionation was not observed in LaCoO 3 by XAS [3], Sarma et al. [4] state that for this material the influence of both types of charge fluctuation is of the same order of magnitude, leading to a very mixed character of the ground state. Charge disproportionation was used to model oxygen nonstoichiometry [6] and Seebeck data [7] of La 12x Sr x CoO 32d . In both cases, however, the best fit implied the simultaneous presence of unrealistically high concentrations of Co 21 and Co 41 . In Sr-doped LaCoO 3 , significant spectral intensities at the Fermi energy have been observed by Sarma et al.[4] using UPS and bremsstrahlung isochromat spectroscopy. They concluded that electron hole states, created by substitution of La 31 by Sr 21 , overlap the top of the wide oxygen 2p band giving rise to a mixed-valency metallic compound. Furthermore, conductivity and Seebeck measurements [7] at high temperatures also indicate metalliclike properties for Sr-doped LaCoO 3 . These observations favor the interpretation in terms of itinerant electron behavior in these solids.The aim of this study is, on the one hand, to improve existing oxygen nonstoichiometry models for the compounds La 12x Sr x CoO 32d by incorporating the delocalized nature of the conduction electron...

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“…The lower oxygen ionic conduction in Fe-and Co-doped gallates can be attributed to stronger Fe-O and Co-O bonds compared to Ni-O, due to anomalous oxidation state of nickel with respect to iron and cobalt. In particular, oxygen-vacancy diffusion coefficients in the perovskite-type compounds increase in the sequence Cr < Fe < Co [17,18], implying that the next member of the series, Ni, has still higher diffusion coefficient. The faster ionic transport in Fecontaining gallates compared to Co-substituted analogues (Fig.3) is associated, most probably, with structural features, namely the larger unit cell volume and smaller distortion of the crystal lattice (Table I and [10]) resulting in more degenerate system of the oxygen-vacancy hopping pathways.…”

Section: Oxygen Ionic Transport Vs Cation Compositionmentioning

confidence: 99%

Permeabilidad de oxígeno en membranas cerámicas de La(Sr,Pr)Ga(Mg)O<sub>3-Î´</sub> con metales de transición

Yaremchenko¹,

Shaula²,

Хартон³

et al. 2004

Bol. Soc. Esp. Ceram. Vidr.

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Acceptor-type doping of perovskite-type La 1-x Sr x Ga 0.80-y Mg y M 0.20 O 3-δ (x = 0-0.20, y = 0.15-0.20, M = Fe, Co, Ni) leads to significant enhancement of ionic conductivity and oxygen permeability due to increasing oxygen vacancy concentration. The increase in strontium and magnesium content is accompanied, however, with increasing role of surface exchange kinetics as permeation-limiting factor. At temperatures below 1223 K, the oxygen permeation fluxes through La(Sr)Ga(Mg,M)O 3-δ membranes with thickness less than 1.5 mm are predominantly limited by the exchange rates at membrane surface. The oxygen transport in transition metal-containing La(Sr)Ga(Mg)O 3-δ ceramics increase in the sequence Co < Fe < Ni. The ionic conduction in these phases is, however, lower than that in the parent compounds, La 1-x Sr x Ga 1-y Mg y O 3-δ . The highest level of oxygen permeation, comparable to that of La (Sr) da lugar a una mejora significativa de la conductividad iónica y de la permeabilidad al oxígeno debido al aumento de la concentración de vacantes de oxígeno. Sin embargo, el aumento de la cantidad de estroncio y magnesio viene acompañado de un aumento de la participación de las cinéticas de intercambio superficial como factor limitante de la permeabilidad. A temperaturas por debajo de 1223 K la permeabilidad al flujo de oxígeno a través de las membranas de La(Sr)Ga(Mg,M)O 3-δ con espesor menor de 1.5 mm está limitado principalmente por las velocidades de intercambio en la superficie de la membrana. El transporte de oxígeno en las cerámicas La(Sr)Ga(Mg)O 3-δ que contienen M aumenta en la secuencia Co < Fe < Ni. La conductividad iónica en estas fases es, sin embargo, menor que en la de los compuestos La 1-x Sr x Ga 1-y Mg y O 3-δ . El mayor nivel de permeabilidad de oxígeno, comparable a la de las fases basadas en La(Sr)Fe (

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Oxygen permeation modelling of perovskites

Cited by 143 publications

References 18 publications

Numerical simulation of ion transport membrane reactors: Oxygen permeation and transport and fuel conversion

Numerical simulation of ion transport membrane reactors: Oxygen permeation and transport and fuel conversion

Use of the Rigid Band Formalism to Interpret the Relationship between O Chemical Potential and Electron Concentration inLa1−xSrx
Lankhorst
¹
,
Bouwmeester
²
,
Verweij
³

1996
Phys. Rev. Lett.
93
9
56
0
View full text Add to dashboard Cite

Permeabilidad de oxígeno en membranas cerámicas de La(Sr,Pr)Ga(Mg)O<sub>3-Î´</sub> con metales de transición

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Oxygen permeation modelling of perovskites

Cited by 143 publications

References 18 publications

Numerical simulation of ion transport membrane reactors: Oxygen permeation and transport and fuel conversion

Numerical simulation of ion transport membrane reactors: Oxygen permeation and transport and fuel conversion

Use of the Rigid Band Formalism to Interpret the Relationship between O Chemical Potential and Electron Concentration inLa1−xSrxLankhorst1, Bouwmeester2, Verweij3 1996Phys. Rev. Lett.939560View full textAdd to dashboardCite

Permeabilidad de oxígeno en membranas cerámicas de La(Sr,Pr)Ga(Mg)O<sub>3-Î´</sub> con metales de transición

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Use of the Rigid Band Formalism to Interpret the Relationship between O Chemical Potential and Electron Concentration inLa1−xSrx
Lankhorst
¹
,
Bouwmeester
²
,
Verweij
³

1996
Phys. Rev. Lett.
93
9
56
0
View full text Add to dashboard Cite