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Producing syngas and hydrogen from biofuels is a promising technology in the modern energy. In this work results of authors’ research aimed at design of supported membranes for oxygen and hydrogen separation are reviewed. Nanocomposites were deposited as thin layers on Ni–Al foam substrates. Oxygen separation membranes were tested in CH4 selective oxidation/oxi-dry reforming. The hydrogen separation membranes were tested in C2H5OH steam reforming. High oxygen/hydrogen fluxes were demonstrated. For oxygen separation membranes syngas yield and methane conversion increase with temperature and contact time. For reactor with hydrogen separation membrane a good performance in ethanol steam reforming was obtained. Hydrogen permeation increases with ethanol inlet concentration, then a slight decrease is observed. The results of tests demonstrated the oxygen/hydrogen permeability promising for the practical application, high catalytic performance and a good thermochemical stability.

Design of oxygen and hydrogen separation membranes is the point of current interest in producing syngas from biofuels. Nanocomposites with a high mixed ionic-electronic conductivity are known to be promising materials for these applications. This work aims at studying performance of oxygen and hydrogen separation membranes based on nanocomposites PrNi0.5Co0.5O3-δ + Ce0.9Y0.1O2-δ and Nd5.5WO11.25-δ + NiCu alloy, respectively. A high and stable performance promising for the practical application was demonstrated for these membranes. For oxygen separation membrane CH4 conversion is up to 50% with H2 content in the outlet feed being up to 25% at 900 °C. For reactor with hydrogen separation membrane complete EtOH conversion was achieved at T ∼ 700 °C even at the highest flow rate, and a high hydrogen permeation (≥1 ml H2 cm−2 min−1) was revealed.

In the field of modern hydrogen energy, obtaining pure hydrogen and syngas and then being able to use them for green energy production are significant problems. Developing solid oxide fuel cells (SOFC) and catalytic membranes for oxygen separation as well as materials for these devices is one of the most likely ways to solve these problems. In this work, the authors’ recent studies in this field are reviewed; the fundamentals of developing materials for SOFC cathodes and oxygen separation membranes’ permselective layers based on research of their oxygen mobility and surface reactivity are presented. Ruddlesden – Popper phases Ln2–xCaxNiO4+δ (LnCNO) and perovskite-fluorite nanocomposites PrNi0.5Co0.5O3–δ–Ce0.9Y0.1O2–δ (PNC–YDC) were studied by isotope exchange of oxygen with C18O2 and 18O2 in flow and closed reactors. For LnCNO a high oxygen mobility was shown (D* ~ 10–7 cm2/s at 700 °C), being provided by the cooperative mechanism of oxygen migration involving both regular and highly-mobile interstitial oxygen. For PNC–YDC dominated a wide fast diffusion channel via fluorite phase and interphases due to features of the redistribution of cations resulting in superior oxygen mobility (D* ~ 10–8 cm2/s at 700 °C). After optimization of composition and nanodomain structure of these materials, as cathodes of SOFC they provided a high power density, while for asymmetric supported oxygen separation membranes – a high oxygen permeability. © 2020 Support of different parts of the work by the Russian Science Foundation (Project 16-13-00112) and the budget project №AAAA-A17-117041110045-9 for Boreskov Institute of Catalysis is gratefully acknowledged. The authors from the Ural Federal University are grateful to the Government of the Russian Federation (Agreement 02.A03.21.0006, Act 211). Ce 0.9 Y 0.1 O 2–δ |Ce 0.9 Gd 0.1 O 2–δ |Ni/Zr 0.84 Y 0.16 O 2–δ anodic half-cells and Ni/Al foam substrates were kindly provided by H.C. Starck, Germany and Powder Metallurgy Institute NAN Belarus, respectively. Authors would like to appreciate International Conference on Advances in Energy Systems and Environmental Engineering (ASEE19, Wroclaw, Poland, June 9-12, 2019) Organization Committee.

The real/atomic structure of single phase homogeneous nanocrystalline Ce0.5Zr0.5O2±δoxides prepared by a modified Pechini route and Ni-loaded catalysts of methane dry reforming on their bases was studied by a combination of neutron diffraction, synchrotron X-ray diffraction, total X-ray scattering and X-ray absorption spectroscopy. The effects of sintering temperature and pretreatment in H2were elucidated. The structure of the mixed oxides corresponds to a tetragonal space group indicating a homogeneous distribution of Ce and Zr cations in the lattice. A pronounced disordering of the oxygen sublattice was revealed by neutron diffraction, supposedly due to incorporation of water into the structure when in contact with air promoted by the generation of anion vacancies in the lattice after reduction or calcination at high temperatures. However, such disordering has not resulted in any occupation of the oxygen interstitial positions in the bulk of the nanodomains.

Novel and stable to carbonization nanocomposite materials based upon Pr2−xNiO4+δ, Pr1−xSmxNi1−yCoyO3−δ and YDC were synthesized via Pechini route and ultrasonic dispersion, and were sintered using conventional and advanced (microwave, e-beam) techniques. Their real/nano structure and transport properties were characterized by sophisticated methods. Nanocomposites have high oxygen mobility due to cooperative mechanism of migration for Pr2−xNiO4+δ and fast channel of diffusion for nanocomposites due to Pr cations’ incorporation into YDC. Power density values of single SOFCs were up to 0.5 W/cm2 at 700 °C, being comparable with that for state-of-the-art cathodes. For oxygen separation membranes, high and stable performance was demonstrated.

This chapter reviews recent advances in developing intermediate-temperature solid oxide fuel cells; oxygen and hydrogen separation membranes; and methods for obtaining advanced oxide, nanocomposite, and nanostructured materials for such devices. All the materials were synthesized by novel methods and characterized by sophisticated techniques. High ionic conductivity and improved oxygen/protonic mobility and surface reactivity were demonstrated. A new approach to building the functional layers was developed. A high-power density of single-button fuel cells in the intermediate-temperature range was reached. Oxygen and hydrogen separation membranes demonstrated promising and stable performance due to fast ionic transport and high catalytic activity of the materials concerned.

Design of materials for solid oxide fuel cells cathodes and oxygen separation membranes and studying their oxygen transport characteristics are important problems of modern hydrogen energy. In the current work, fundamentals of such materials design based on characterization of their oxygen mobility by oxygen isotope exchange with C18O2 and 18O2 in flow and closed reactors for samples of Ruddlesden - Popper-type oxides Ln2-xCaxNiO4+δ, perovskite-fluorite nanocomposites PrNi0.5Co0.5O3-δ - Ce0.9Y0.1O2-δ, etc. are presented. Fast oxygen transport was demonstrated for PNC - YDC (DO ~10-8 cm2/s at 700°C) nanocomposites due to domination of the fast diffusion channel involving oxygen of the fluorite phase with incorporated Pr cations and developed perovskite-fluorite interfaces. For LnCNO materials a high oxygen mobility (DO ~10-7 cm2/s at 700°C) provided by the cooperative mechanism of its migration was demonstrated. Depending on Ca dopant content and Ln cation nature, in some cases 1-2 additional channels of the slow diffusion appear due to decreasing the interstitial oxygen content and increasing the energy barrier for oxygen jumps due to cationic size effect. Optimized by the chemical composition and nanodomain structure materials of these types demonstrated a high performance as SOFC cathodes and functional layers in asymmetric supported oxygen separation membranes. © The Authors, published by EDP Sciences, 2019. Russian Science Foundation, RSF: 16-13-00112 Support by the Russian Science Foundation (Project 16-13-00112) is gratefully acknowledged. The authors from the Ural Federal University are grateful to the Government of the Russian Federation (Agreement 02.A03.21.0006, Act 211). Ce0.9Y0.1O2-δ|Ce0.9Gd0.1O2-δ|Ni/Zr0.84Y0.16O2-δ anodic half-cells and Ni/Al foam substrates were kindly provided by H.C. Starck, Germany and Powder Metallurgy Institute NAN Belarus, respectively.

Progress in design of thermal barrier coatings (TBCs) is based upon application of new materials and deposition techniques. In this work traditional NiCrAl bond coat YSZ top coat were deposited on Ni superalloy substrate by inexpensive dry detonation spraying, while finishing layers of oxide nanocomposites (LaAlO3–La2Zr2O7, LaAlO3–LaCuAl11O19) were deposited on YSZ by slip casting. Complex oxides were prepared via Pechini route. Thin (~ 20 μm) finishing layers were deposited by slip casting of suspensions of oxides mixture in isopropanol with addition of polyvinylbutyral. Genesis of the texture, composition and real/defect structure of bulk nanocomposite materials and deposited layers after annealing in air up to 1300 °C as well as after series of thermal shocks by heating up to 1200 °C by H2–O2 burner were studied by combination of diffraction (high resolution SEM and TEM with EDX, XRD on synchrotron radiation) and spectroscopic (UV–Vis, EXAFS, laser-excited Dy3 + luminescence spectra) methods. Thermal conductivity of nanocomposites and TBCs was determined by using NETZSCH LFA 457 MicroFlash. Nanocomposites were shown to retain porosity as well as nanosizes of disordered domains of oxide phases even after sintering at high temperatures. A good adhesion and compatibility of all layers in TBCs were demonstrated, while in general disordering of the oxides structure in deposited layers was higher than that in bulk materials due to the effect of depositing procedure and interaction between layers. This provides a low thermal conductivity of nanocomposites and functionally graded TBC. After 90 thermal shocks neither layers spallation nor cracks were revealed, 8YSZ and finishing layers retaining porosity, nanocrystallinity and disordering required for a low thermal conductivity and cracks trapping.

Mixed nanocrystalline Ce-Zr-O oxides (Ce/Zr = 1 or 7/3) were prepared by modified Pechini route using ethylene glycol solutions of metal salts. Detailed characterization of their real structure and surface properties by X-ray diffraction on synchrotron radiation with the full-profile Rietveld analysis, high resolution electron microscopy with elemental analysis, Raman spectroscopy, UV-Vis and X-ray photoelectron spectroscopy revealed a high homogeneity of cations distribution in nanodomains resulting in stabilization of disordered cubic phase. This provides a high dispersion of NiO loaded on these mixed oxides by wet impregnation, a high reactivity and mobility of oxygen in these catalysts and strong interaction of Ni with support in the reduced state. This helps to achieve a high activity and coking stability of developed catalysts in CH4 dry reforming in feeds with CH4 concentration up to 15% and CH4/CO2 ratio =1.

The main aspects of the cathode materials morphology for Intermediate Temperature Solid Oxide Fuel Cells (IT SOFC) are considered in this paper. The approaches for estimation of their basic properties, e.g. oxygen mobility and surface reactivity, are described and the results of different techniques (e.g. weight and conductivity relaxation, oxygen isotope exchange) application for studies of powders and dense ceramic materials are compared. The Ruddlesden-Popper type phases (e.g. Pr2NiO4) provide enhanced oxygen mobility due to cooperative mechanism of oxygen interstitial migration. For perovskites, the oxygen mobility is increased by doping, which generates oxygen vacancies or decreases metal-oxygen bond strength. Nonadditive increasing of the oxygen diffusion coefficients found that for perovskite-fluorite nanocomposites, it can be explained by the fast oxygen migration along perovskitefluorite interfaces. Functionally graded nanocomposite cathodes provide the highest power density, the lowest area specific polarization resistance, and the best stability to degradation caused by the surface layer carbonization/ hydroxylation, thus being the most promising for thin film IT SOFC design.

Bi-doped lanthanum manganite La 1 − x Bi x MnO 3 + y (x = 0–1) (LBM) and fluorite-like Bi 1.5 Y 0.3 Sm 0.2 O 2 oxide (BYS) were synthesized via Pechini route and characterized by a complex of physical–chemical methods. Oxides with reasonable high lattice oxygen mobility and reactivity were selected for LBM + BYS nanocomposites preparation. LBM + BYS composites were prepared via ultrasonic dispersion of the mixture of perovskite and fluorite powders in isopropanol with addition of polyvinyl butyral. Studies of the real structure evolution of composites at sintering under air up to 850 °C revealed some redistribution of elements between the phases without new phase formation. The oxygen mobility and reactivity of powdered LBM, BYS and composites were estimated by the oxygen isotope exchange (using both static and flow (SSITKA) modes) and O 2 TPD, while weight relaxation technique was applied for studies of oxygen mobility in dense composite pellets. The oxygen mobility of composites was shown to increase with sintering temperature exceeding additive level, which suggests a positive role of interfaces as fast oxygen migration paths. For best LBM + BYS composites, the value of the oxygen chemical diffusion coefficient exceeds that of well known LSFC–GDC composite.

Open cell metal foams made from Ni, Fe–Cr steel and Ni–Al intermetallic were studied as candidate catalyst supports for the internal indirect methane steam reforming. All the samples exhibited good corrosive resistance during 500–1000 h testing in H2–H2O–Ar environment at 600 °C. NiO/8YSZ composite based catalysts doped with fluorite-like (Pr0.3Ce0.35Zr0.35O2) or perovskite-like (La0.8Pr0.2Mn0.2Cr0.8O3) complex oxides with high lattice oxygen mobility and promoted with Pt or Ru were prepared and deposited on the foam-structure supports. Both good catalyst adhesion and stable catalyst performance were achieved in the case of the Ni–Al foam supported catalysts. The Fe–Cr support reacted with the catalytic active components resulting in fast catalyst deactivation. The foam supported catalyst performance was compared with the same catalyst prepared in a form of 0.25 mm fraction. Porous supports with different porosities were prepared by the metal foam deformation and the catalyst performance depending on the support porosity (75–95%) was studied.

Main features of structured catalysts performance in bio-fuels reforming into syngas at lab-scale and pilot-scale levels using specially designed reactors and kinetic installations allowing to broadly tune the operational parameters are presented. Effects of the nature of nanocomposite active component comprised of Ru + Ni nanoparticles on bulk/alumina-supported perovskite or Mn–Cr–O spinel, type of substrate (Ni–Al alloy and SiC(Al 2 O 3 )/Al–Si–O foam substrates, Fechraloy microchannel plates or gauzes protected by thin corundum layer), type of fuel (natural gas, ethanol, acetone, ethyl acetate glycerol), feed composition and temperature on yield of syngas/byproducts and performance stability are considered. The best performance in real feeds with syngas yield approaching equilibrium at short contact times without any heat/mass transfer effects along with a high thermochemical stability were demonstrated for catalyst on heat-conducting microchannel substrate. Oxygen addition to the feed in optimized amounts allows to suppress coking and stabilize performance even for the case of such reactive fuel as glycerol only slightly affecting syngas yield.