Hydrogen permeation characteristics of La27Mo1.5W3.5O55.5

Vøllestad, Einar; Vigen, Camilla K.; Magrasó, Anna; Haugsrud, Reidar

doi:10.1016/j.memsci.2014.03.011

Cited by 45 publications

(39 citation statements)

References 27 publications

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“…The activation energies at high temperatures with wet sweep gas, 79-92 kJ mol À 1 (E 1 a in Table 1), are similar to that reported for pure LWM, 95 kJ mol À 1 [12]. These values compare well with activation energies of oxide ion transport in non Mo-doped material, 85 and 93 kJ mol À 1 [31,35], which is consistent with the apparent hydrogen permeability being predominated by water splitting and limited by oxide ion transport under these conditions.…”

Section: Discussionsupporting

confidence: 76%

“…The sample was cooled in wet 50% H 2 and XRD analysis revealed formation of additional phases, as reported for LWM by Vøllestad et al [12]. A detailed investigation of the degradation phenomenon including long-term testing will be presented in a forthcoming publication.…”

Section: H 2 Permeation Measurementsmentioning

confidence: 75%

“…Hydrogen permeability is thereby limited by the slowest of these species as described by the ambipolar conductivity of the material. Two main strategies are applied for enhancing transport of the less conducting species, which for chemically stable proton conductors often is electronic: (1) dissolution of multivalent dopants such as Ru, Eu, and Mo, as demonstrated for BaCeO 3À δ [9], SrCeO 3À δ [10] and La 27 W 5 O 55.5À δ [11,12], respectively; (2) use of a percolating metal phase of for instance Ni or Pd in a cermet composite as demonstrated for BaCeO 3À δ , BaZrO 3À δ and CeO 2À δ based ceramics [13][14][15][16][17]. Unemoto et al [18] employed a proton conducting and an electron conducting oxide in their investigation of SrZrO 3À δ -SrFeO 3À δ ceramic-ceramic composites (cercer), which showed considerable hydrogen permeability albeit lower than what was estimated from ambipolar conductivities.…”

Section: Introductionmentioning

confidence: 99%

“…The formula unit may therefore be written La 28 À x W 4 þ x O 54 þ 3x/2 v 2 À 3x/2 À δ , where x quantifies W substituted on La sites and v denotes inherently vacant oxygen sites [35]. Vøllestad et al [12] recently characterized the hydrogen permeability of La 27 W 3.5 Mo 1.5 O 55.5 À δ , where the Mosubstitution substantially increases n-type electronic conductivity under reducing conditions without significantly altering the protonic conductivity [11].…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Hydrogen separation membranes based on dense ceramic composites in the La27W5O55.5–LaCrO3 system

Polfus

Xing

Fontaine

et al. 2015

Journal of Membrane Science

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a b s t r a c tSome compositions of ceramic hydrogen permeable membranes are promising for integration in high temperature processes such as steam methane reforming due to their high chemical stability in large chemical gradients and CO 2 containing atmospheres. In the present work, we investigate the hydrogen permeability of densely sintered ceramic composites (cercer) of two mixed ionic-electronic conductors: La 27 W 3.5 Mo 1.5 O 55.5 À δ (LWM) containing 30, 40 and 50 wt% La 0.87 Sr 0.13 CrO 3 À δ (LSC). Hydrogen permeation was characterized as a function of temperature, feed side hydrogen partial pressure (0.1-0.9 bar) with wet and dry sweep gas. In order to assess potentially limiting surface kinetics, measurements were also carried out after applying a catalytic Pt-coating to the feed and sweep side surfaces. The apparent hydrogen permeability, with contribution from both H 2 permeation and water splitting on the sweep side, was highest for LWM70-LSC30 with both wet and dry sweep gas. The Pt-coating further enhances the apparent H 2 permeability, particularly at lower temperatures. The apparent H 2 permeability at 700 1C in wet 50% H 2 was 1.1 Â 10 À 3 mL min À 1 cm À 1 with wet sweep gas, which is higher than for the pure LWM material. The present work demonstrates that designing dual-phase ceramic composites of mixed ionic-electronic conductors is a promising strategy for enhancing the ambipolar conductivity and gas permeability of dense ceramic membranes.

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Section: Discussionsupporting

confidence: 76%

Section: H 2 Permeation Measurementsmentioning

confidence: 75%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Hydrogen separation membranes based on dense ceramic composites in the La27W5O55.5–LaCrO3 system

Polfus

Xing

Fontaine

et al. 2015

Journal of Membrane Science

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“…Recently, Mo-substituted lanthanum tungstate membranes were studied, [27][28][29] and were found to exhibit high mixed proton-electron conductivities. Therefore, in this paper, Mo-substituted lanthanum tungstate La 5.5 W 0.6 Mo 0.4 O 11.25-δ (LWM04) was developed as a mixed proton-electron conducting membrane material.…”

mentioning

confidence: 99%

A CO₂‐stable hollow‐fiber membrane with high hydrogen permeation flux

Chen

Liao

et al. 2015

AIChE Journal

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A Mo-substituted lanthanum tungstate mixed proton-electron conductor, La 5.5 W 0.6 Mo 0.4 O 11.25-δ (LWM04), was synthesized using solid state reactions. Dense U-shaped LWM04 hollow-fiber membranes were successfully prepared using wet-spinning phase-inversion and sintering. The stability of LWM04 in a CO 2 -containing atmosphere and the permeation of hydrogen through the LWM04 hollow-fiber membrane were investigated in detail. A high hydrogen permeation flux of 1.36 ml/min·cm 2 was obtained for the U-shaped LWM04 hollow-fiber membranes at 975°C when a mixture of 80% H 2 -20% He was used as the feed gas and the sweep side was humidified. Moreover, the hydrogen permeation flux did not significantly decrease over 70 h of operation when fed with a mixture containing 25% CO 2 , 50%H 2 , and 25% He, indicating that the LWM04 hollow-fiber membrane has good stability under a CO 2 -containing atmosphere.

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