Study of the Transport Properties of the Mixed Ionic Electronic Conductor Ce1−xTbxO2−δ + Co (x = 0.1, 0.2) and Evaluation As Oxygen-Transport Membrane

Balaguer, María; Solís, Cecilia; Serra, José M.

doi:10.1021/cm103581w

Cited by 69 publications

(89 citation statements)

References 43 publications

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“…In several studies, 17,20,25 it has been reported that the electronic conductivity of Pr-doped ceria can be well described by a small polaron mechanism. Hence, mobility and conductivity will scale with temperature according to:…”

Section: Discussionmentioning

confidence: 99%

“…17,42,43 The enhanced oxygen flux is reported to be due to the enhanced electronic conductivity. However, we did not observe enhanced flux for the cobalt-containing sample, instead the opposite trend was observed.…”

Section: Thermalmentioning

confidence: 99%

“…[13][14][15][16][17][18] Among rare earth elements, Praseodymium (Pr) and Terbium (Tb) show significant redox activity * Electrochemical Society Member.…”

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Ionic/Electronic Conductivity, Thermal/Chemical Expansion and Oxygen Permeation in Pr and Gd Co-Doped Ceria Pr_xGd_0.1Ce_0.9-xO_1.95-δ

Cheng

Chatzichristodoulou

Søgaard

et al. 2017

J. Electrochem. Soc.

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The oxygen permeation flux of Ce 0.9 Gd 0.1 O 1.95-δ (CGO)-based oxygen transport membranes under oxidizing conditions is limited by the electronic conductivity of the material. This work aims to enhance the bulk ambipolar conductivity of CGO by partial substitution of Ce with the redox active element Pr. A series of compositions of Pr x Gd 0.1 Ce 0.9-x O 1.95-δ (x = 0, 0.02, 0.05, 0.08, 0.15, 0.25, 0.3 and 0.4) was prepared by solid state reaction. X-ray powder diffraction (XPD) indicates that Pr is completely dissolved in the fluorite structure up to 40 at.%. Pronounced nonlinear thermal expansion behavior was observed as a function of temperature, due to the simultaneous contributions of both thermal and chemical expansion. The electronic and ionic conductivities were measured as a function of temperature and oxygen partial pressure. Within the range from 10 to 15 at.% Pr, a drastic drop of the activation energy of the hole mobility and an abrupt increase of the hole conductivity at low temperature was observed. The behavior could be rationalized by a simple percolation model. Oxygen permeation fluxes through disk shaped samples fed with air on one side and N 2 on the other side were also measured. The oxygen flux through Pr 0.05 Gd 0.1 Ce 0.85 O 1.95-δ was higher than that for CGO by one order of magnitude owing to the enhanced electronic conductivity albeit the flux is still limited by the electronic conductivity. In terms of the electronic and ionic conductivity, the estimated maximum oxygen permeation flux of a 10 μm Pr 0.4 Gd 0.1 Ce 0.9 O 1.95-δ -based membrane exceeds 10 Nml cm −2 min −1 at 900 • C under a small oxygen potential gradient (0.21/10 −3 bar) which is promising for use in oxygen production and in oxy-fuel combustion. Also the material may be well applicable to SOFC/SOEC composite electrodes where mixed conductivity is also desirable. Dense ceramic oxygen transport membranes (OTMs) could potentially be applied for production of high purity oxygen for medical purposes, supply of oxygen in the steel industry, oxy-fuel combustion schemes, as well as in the cement and glass industries. Also, importantly, OTMs can beneficially be integrated with a biomass gasifier, allowing production of syngas (CO and H 2 ), which is a precursor for a variety of high value chemicals. 1 Besides being applicable for OTMs, 2 acceptor doped-ceria has been intensively studied for use in a number of other applications e.g. solid oxide fuel cells (SOFCs), 3 solid oxide electrolysis cells (SOECs) 4 and for electrocatalysis. 5 In particular, acceptor doped ceria (e.g. CGO) is interesting owing to high oxide ion conductivity (0.12 Scm −1 for Gd 0.1 Ce 0.9 O 1.95-δ at 900• C 6 ), appreciable electrocatalytic activity, high electronic conductivity under reducing conditions, and excellent chemical stability under harsh reducing and even corrosive gaseous conditions. 3,7 Kaiser et al. 8 reported that the oxygen permeation flux of a 27 μm asymmetric 10 at.% Gd-doped ceria-based membrane exceeds 10 ml cm −2 min −1 under a gradie...

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Section: Discussionmentioning

confidence: 99%

Section: Thermalmentioning

confidence: 99%

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Ionic/Electronic Conductivity, Thermal/Chemical Expansion and Oxygen Permeation in Pr and Gd Co-Doped Ceria Pr_xGd_0.1Ce_0.9-xO_1.95-δ

Cheng

Chatzichristodoulou

Søgaard

et al. 2017

J. Electrochem. Soc.

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“…In contrast, at higher temperatures the use of a protective layer only slightly affected the permeation process, which can be related to the higher ambipolar conductivity of the CGO layer in this temperature range, especially if small amounts of cobalt are present in the layer. [ 35 ] …”

Section: Electrochemical Studymentioning

confidence: 99%

Development of CO₂ Protective Layers by Spray Pyrolysis for Ceramic Oxygen Transport Membranes

García-Torregrosa

Lobera

Solís

et al. 2011

Advanced Energy Materials

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Ceramic mixed ionic–electronic conducting (MIEC) membranes enable very selective oxygen separation from air at high temperatures. Two major potential applications of oxygen‐transport membranes are: i) oxygen production for oxyfuel power plants, and, ii) integration within high‐temperature catalytic membrane reactors for methane or alkane upgrading by selective oxidative conversions. However, these applications involve contact with carbon‐bearing atmospheres and most state‐of‐the‐art highly permeable MIEC membranes do not tolerate operation under CO2‐rich environments due to carbonation processes. The present contribution shows our first attempts in the development of ceria‐based protective thin layers on monolithic LSCF membranes. Gd‐doped ceria (CGO) deposition is carried out by air blast spray pyrolysis on mirror‐polished LSCF disc membranes. The layer thickness is maintained below 0.4 μm in order to prevent the formation of cracks during thermal cycling and minimize limitations caused by the reduced oxygen permeability through the ceria layer. After optimization of the spraying process, smooth crack‐free dense coatings are obtained with high crystallinity in the as‐deposited state. The layers are characterized by XRD, SEM, AFM, DC‐conductivity measurements, interferometry and optical microscopy. Oxygen separation is studied on coated LSCF using air as the feed and argon/CO2 mixtures as the sweep gas in the temperature range 650–1000°C. The protected membrane exhibits a higher stability than the uncoated LSCF membrane, although the nominal oxygen flux is slightly reduced at temperatures below 850°C due to the limited ambipolar conductivity of doped ceria in the range of oxygen partial pressures investigated. Moreover, the protective layer (250 nm thickness) remains stable after the permeation testing.

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“…The addition of the ceria phase enhances the ionic transport, increasing the triple phase boundary (TPB) length in the electrode where gaseous oxygen comes into contact with the ion and electron conducting phases, and the electrochemical reactions take place 7 . Furthermore, by introducing lanthanide elements with mixed valence (as Pr and Tb) in the ceria lattice, mixed ionic-electronic conductivity (MIEC) may be promoted even at high oxygen partial pressures (pO 2 > 10 -5 atm) [8][9][10][11] . Thus, the TPB area is further increased since the whole surface area of the ceria in contact with the gas is active for the electrochemical reaction in addition to the LSM-electrolyte interface.…”

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confidence: 99%

Optimization of SOFC Composite Cathodes Based on LSM and Doped Cerias Ce_0.8Ln_0.2O_2-δ(Ln = Gd, Er, Tb and Pr)

Navarrete¹,

Balaguer²,

Vert³

et al. 2016

J. Electrochem. Soc.

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Composites made of La 1-x Sr x MnO 3−δ (LSM) and lanthanide doped ceria (Ce 0.8 Ln 0.2 O 2-δ , Ln=Gd, Er, Tb and Pr) have been proposed as robust and high-performing solid oxide fuel cell cathodes. The addition of small amounts of highly-dispersed CoO x into the electrode promoted the formation of bridges among LSM-ceria particles. These resulted in the reduction of the required sintering temperature due to the enhancement of the sintering and proper ionic and electronic percolation pathways. In addition, Pr as a multivalent cation dopant in ceria showed the best electrochemical results towards oxygen reduction when the electrode sintering temperature is kept at 1000 °C.

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Study of the Transport Properties of the Mixed Ionic Electronic Conductor Ce_1−xTb_xO_2−δ + Co (x = 0.1, 0.2) and Evaluation As Oxygen-Transport Membrane

Cited by 69 publications

References 43 publications

Ionic/Electronic Conductivity, Thermal/Chemical Expansion and Oxygen Permeation in Pr and Gd Co-Doped Ceria Pr_xGd_0.1Ce_0.9-xO_1.95-δ

Ionic/Electronic Conductivity, Thermal/Chemical Expansion and Oxygen Permeation in Pr and Gd Co-Doped Ceria Pr_xGd_0.1Ce_0.9-xO_1.95-δ

Development of CO₂ Protective Layers by Spray Pyrolysis for Ceramic Oxygen Transport Membranes

Optimization of SOFC Composite Cathodes Based on LSM and Doped Cerias Ce_0.8Ln_0.2O_2-δ(Ln = Gd, Er, Tb and Pr)

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Study of the Transport Properties of the Mixed Ionic Electronic Conductor Ce1−xTbxO2−δ + Co (x = 0.1, 0.2) and Evaluation As Oxygen-Transport Membrane

Cited by 69 publications

References 43 publications

Ionic/Electronic Conductivity, Thermal/Chemical Expansion and Oxygen Permeation in Pr and Gd Co-Doped Ceria PrxGd0.1Ce0.9-xO1.95-δ

Ionic/Electronic Conductivity, Thermal/Chemical Expansion and Oxygen Permeation in Pr and Gd Co-Doped Ceria PrxGd0.1Ce0.9-xO1.95-δ

Development of CO2 Protective Layers by Spray Pyrolysis for Ceramic Oxygen Transport Membranes

Optimization of SOFC Composite Cathodes Based on LSM and Doped Cerias Ce0.8Ln0.2O2-δ(Ln = Gd, Er, Tb and Pr)

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Study of the Transport Properties of the Mixed Ionic Electronic Conductor Ce_1−xTb_xO_2−δ + Co (x = 0.1, 0.2) and Evaluation As Oxygen-Transport Membrane

Ionic/Electronic Conductivity, Thermal/Chemical Expansion and Oxygen Permeation in Pr and Gd Co-Doped Ceria Pr_xGd_0.1Ce_0.9-xO_1.95-δ

Ionic/Electronic Conductivity, Thermal/Chemical Expansion and Oxygen Permeation in Pr and Gd Co-Doped Ceria Pr_xGd_0.1Ce_0.9-xO_1.95-δ

Development of CO₂ Protective Layers by Spray Pyrolysis for Ceramic Oxygen Transport Membranes

Optimization of SOFC Composite Cathodes Based on LSM and Doped Cerias Ce_0.8Ln_0.2O_2-δ(Ln = Gd, Er, Tb and Pr)