Novel Composite Cermet for Low-Metal-Content Oxygen Separation Membranes

Ruiz‐Trejo, Enrique; Boldrin, Paul; Lubin, Alexandra; Tariq, Farid; Fearn, Sarah; Chater, Richard J.; Cook, Stuart N.; Atkinson, A.; Gruar, Robert I.; Tighe, Christopher J.; Darr, Jawwad A.; Brandon, Nigel P.

doi:10.1021/cm501490n

Cited by 31 publications

(55 citation statements)

References 45 publications

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“…p Ag [5] where C O and D represent the solubility and diffusion coefficient of oxygen atoms in silver, L Ag is the characteristic length of silver droplets in the Ag-ScSZ composite while the exponent p Ag takes into account the non-uniformity of diffusion within a silver droplet. D is assumed to be independent of oxygen concentration and C O is considered spatially uniform (i.e., no oxygen gradients) because impedance is collected at open-circuit equilibrium.…”

Section: Methodsmentioning

confidence: 99%

“…5 Oxygen can be separated from air using a double phase membrane with an oxygen-ion conductor, e.g. scandia stabilized zirconia, and an electronic conductor, such as silver, that acts as a very efficient oxygen reducing agent.…”

Section: 3mentioning

confidence: 99%

“…Therefore, the double-phase approach is gaining interest again as it gives more flexibility to tailor the choice of conducting materials and their microstructure, as recently reported through the use of two conductive ceramic materials -an ionic one and an electronic one-such as Ce 0.9 Gd 0.1 O 2-x /LSCF 11 and Ag/Ce 0.9 Gd 0.1 O 2-x . 5 Especially, it has been shown that low levels of Ag can yield the necessary percolation for operation well below the 30-40 vol % usually considered as indispensable to achieve percolation. 12,13 In this paper, reduction of oxygen, oxygen transport and separation in the intermediate temperature regime is demonstrated in a composite z E-mail: eruiztre@imperial.ac.uk membrane of scandia-stabilized zirconia (ScSZ) and silver.…”

mentioning

confidence: 99%

“…Although currently scandia is a relatively expensive material, ScSZ's growing use as electrolyte in solid oxide fuel cells may lower its price. 14 The use of Tollens' reagent to fabricate metal ceramic composites for a variety of purposes has been reported recently in applications such as oxygen separation, 5 methane reforming, 15 hydrogen separation, 16 magnetic refrigeration 17 and anode fabrication. 18,19 In this work, the composite membrane fabrication is presented in detail that allows reproducibility and it is followed by characterization by SEM, XRD and conductivity tests.…”

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confidence: 99%

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Oxygen Reduction, Transport and Separation in Low Silver Content Scandia-Stabilized Zirconia Composites

Ruiz‐Trejo¹,

Bertei²,

Maserati³

et al. 2017

J. Electrochem. Soc.

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Dense composites of silver and Sc-stabilized ZrO 2 (Ag-ScSZ) are manufactured from ScSZ sub-micrometric particles coated with silver using Tollens' reagent. A composite with 8.6 vol % of silver exhibits metallic conductivity of 186 S cm −1 and oxygen flux of 0.014 μmol cm −2 s −1 at 600 • C for a 1-mm thick membrane when used as a pressure-driven separation membrane between air and argon. To gain insight into the role of oxygen transport in Ag and ScSZ, a dense non-percolating sample (Ag 4.7 vol%) is analyzed by impedance spectroscopy and the transport of oxygen through both phases is modelled. Oxygen transport takes place in both silver and ScSZ but it is still dominated by transport in the ionic conductor and therefore a large volume fraction of the ion conductor is beneficial for the separation. The oxygen transport in the silver clusters inside the composite is dominated by diffusion of neutral species and not by the charge transfer reaction at the interface between ScSZ and Ag, yet small silver particles on the surface improve the reduction of oxygen. Oxygen reduction is highly promoted by silver on the surface and there are no limitations of charge transfer at the interface between silver and ScSZ. The capability of metallic silver to reduce oxygen has been long known and recorded since Lucas reported it to Dalton as early as 1818 1 but better understood and quantified over the last 50 years. 2,3This particular capability of silver can be exploited to incorporate oxygen into a solid system, be it a solid oxide fuel cell cathode 4 or an oxygen separation membrane. 5 Oxygen can be separated from air using a double phase membrane with an oxygen-ion conductor, e.g. scandia stabilized zirconia, and an electronic conductor, such as silver, that acts as a very efficient oxygen reducing agent. Scandia stabilized zirconia is known to have higher conductivity than yttria stabilized zirconia since it was first reported in 1900 by Nernst 6 but identified as an oxygen ion conductor by Wagner 7 several decades later. The use of double-phase metal ceramic composites to separate oxygen from air was first described by Mazanec, 8 who mixed Pd or Pt with YSZ and used the composite to drive chemical reactions. Although feasible, this approach normally requires large amounts of expensive metal to achieve percolation, ranging from 30 to 50 vol %, so that composite membranes cannot compete with the high oxygen flux reported in single phase perovskites, such as those reported by Teraoka 9 in 1985. To date, most of the research in high temperature oxygen separation is still performed in mixed ionic electronic conductive perovskites ABO 3 , where A is one or more lanthanides and/or alkaline earths and B one or more transition metal oxides, for example Nonetheless, these materials have two persistent problems: the high operating temperatures (>800 • C) and the unsatisfactory chemical and mechanical stability in operating conditions. Furthermore, the chemical composition of the material affects both the stability and the oxygen sepa...

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Section: Methodsmentioning

confidence: 99%

Section: 3mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Oxygen Reduction, Transport and Separation in Low Silver Content Scandia-Stabilized Zirconia Composites

Ruiz‐Trejo¹,

Bertei²,

Maserati³

et al. 2017

J. Electrochem. Soc.

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“…3 The mixed-conducting perovskite-type compounds, 4,5 ceramic composites, [6][7][8][9] and cermets [10][11][12][13] are used as ITM materials. The practicalities for incorporating ceramic membrane materials into industrial processes are discussed in comprehensive reviews.…”

mentioning

confidence: 99%

Oxygen Ion Transport in Molten Oxide Membranes for Air Separation and Energy Conversion

Климашин

Белоусов

2017

J. Electrochem. Soc.

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Molten oxide membranes (MOMs) are a new class of ion transport inorganic membranes which demonstrate superior oxygen selectivity and permeability and could be used in electrochemical devices such as molten oxide fuel cells (MOFCs) and oxygen separators for energy conversion and air separation, respectively [Acc. Chem. Res., 50, 273 (2017)]. However, oxygen ion transport mechanisms in MOM materials are not clear enough. Understanding the oxygen ion transport mechanisms in molten oxides is important for the discovery of new MOM materials with enhanced performances that can enable the operation of the electrochemical devices more efficiently. Here we suggest an approach that adapts a dynamic polymer chain model, developed for specific molten oxides, to a wide range of melts. This generic model can evaluate the oxygen permeation fluxes through different MOM materials that are comparable to experimental data. The study of ion transport membrane (ITM) materials and processes is a rapidly expanding research interest field. This is due to the fact that the ITM-based technology modules have the potential to improve the efficiency and environmental performances of energy generation systems.1,2 ITM can separate high purity oxygen from air at elevated temperatures and have the potential to reduce the cost of oxygen production in comparison with the conventional cryogenic process.3 The mixed-conducting perovskite-type compounds, 4,5 ceramic composites, 6-9 and cermets 10-13 are used as ITM materials. The practicalities for incorporating ceramic membrane materials into industrial processes are discussed in comprehensive reviews. 1,2Recently, the molten oxide membrane (MOM) materials have been developed. 14,15 This MOM materials consist of solid grains and intergranular liquid channels. The intergranular liquid channels provide the membrane material high ionic conductivity, gas tightness, and ductility. This last property allows us to deal successfully with the problem of thermal incompatibility (difference in coefficient of thermal expansion, CTE).There 14,15 Transport properties (electrical conductivity, oxygen ion transport number, and oxygen and nitrogen permeation fluxes) of these MOM materials have been measured. [16][17][18][19][20] These membrane materials showed high oxygen selectivity and permeability. The ease of the MOM materials fabrication, combined with competitive oxygen permeability and superior oxygen selectivity, demonstrates a promising application.Understanding the oxygen ion transport mechanisms in molten oxides is important for the discovery of new MOM materials that can enable the oxygen separation and energy conversion more efficiently. Recently, a dynamic polymer chain model for oxygen ion transport in molten V 2 O 5 has been developed. [21][22][23] In this paper, we suggest an approach that adapts the dynamic polymer chain model to a wide range of melts. This generic model can predict the gas permeation fluxes through molten oxide 14,15 and carbonate [24][25][26][27][28][29] membrane materials that a...

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ChemInform Abstract: Novel Composite Cermet for Low‐Metal‐Content Oxygen Separation Membranes.

Ruiz‐Trejo¹

2014

ChemInform

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0.8Sm0.2O1.90 composite (manufactured from ceramic nanoparticles coated by electroless deposition of Ag) is used to separate oxygen from air. At 700 C, the oxygen flux rate is 0.04 molcm -2 s -1 using Ar as sweep gas and 0.17 molcm -2 s -1 using 5% hydrogen in argon. The ease of membrane fabrication and the encouraging oxygen permeation rates demonstrate the promise of the composite material for high-purity oxygen separation below 700 C for technological applications. - (RUIZ-TREJO*, E.; et al.; Chem. Mater. 26 (2014) 13, 3887-3895, http://dx.doi.org/10.1021/cm501490n ; Dep. Earth Sci. Eng., Imp. Coll., London SW7 2AZ, UK; Eng.) -W. Pewestorf 37-229

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Novel Composite Cermet for Low-Metal-Content Oxygen Separation Membranes

Cited by 31 publications

References 45 publications

Oxygen Reduction, Transport and Separation in Low Silver Content Scandia-Stabilized Zirconia Composites

Oxygen Reduction, Transport and Separation in Low Silver Content Scandia-Stabilized Zirconia Composites

Oxygen Ion Transport in Molten Oxide Membranes for Air Separation and Energy Conversion

ChemInform Abstract: Novel Composite Cermet for Low‐Metal‐Content Oxygen Separation Membranes.

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