Anton I. Lukashevich

Pt-Supported Nanocrystalline Ceria-Zirconia Doped with La, Pr or Gd: Factors Controlling Syngas Generation in Partial Oxidation/Autothermal Reforming of Methane or Oxygenates

Nanocrystalline CeO2-ZrO2 (Ce:Zr 1:1) samples doped with La, Pr or Gd cations (containing up to 30 at.%) were prepared via the Pechini route. Pt (1.4 wt.%) was supported via impregnation with H2PtCl6 solution followed by drying and calcination. The samples’ surface features were studied by SIMS and FTIRS of adsorbed CO. The oxygen mobility was characterized by the dynamic oxygen isotope exchange and H2 TPR. Catalytic activity was studied in the flow installation using diluted feeds (0.7% CH4 +0.5% O2 or 1% C3H6O + 0.5% O2 +0.5% H2O in He). In the selective oxidation of methane (POM), the catalytic activity correlates with Pt dispersion controlled by the oxidized sample’s ability to stabilize Pt2+ cations as precursors of small reactive Pt clusters formed under reaction conditions. This is favoured by a larger doping cation (La) and a developed network of nanodomain boundaries. At comparable Pt dispersion, the highest performance was demonstrated by a La-doped system, which correlates with the highest surface/near-surface oxygen mobility controlled by the strength of Ce-O bonds in the surface layer. In the autothermal reforming of acetone, the activity trends differ from those in POM because of the more prominent role of the oxygen mobility required to prevent surface coking.

Nanocomposite Catalysts for Steam Reforming of Methane and Biofuels: Design and Performance

Vladislav Sadykov, Natalia Mezentseva, Galina Alikina, Rimma Bunina, Vladimir Pelipenko, Anton Lukashevich, Zakhar Vostrikov, Vladimir Rogov, Tamara Krieger, Arkady Ishchenko, Vladimir Zaikovsky, Lyudmila Bobrova, Julian Ross, Oleg Smorygo, Alevtina Smirnova, Bert Rietveld and Frans van Berkel, 1Boreskov Institute of Catalysis, Novosibirsk State University, 2University of Limerick, 3Powder Metallurgy Institute, 4Eastern Connecticut State University, 5Energy Research Center of the Netherlands, 1Russia 2Ireland 3Belarus 4USA 5Netherlands

Performance of monolithic catalysts with complex active component in partial oxidation of methane into syngas: experimental studies and modeling

Publisher Summary Partial oxidation of methane (POM) on monolithic catalysts at short contact times is a promising process for designing compact syngas generators. As is demonstrated for Rh- or Pt- supported catalysts, the optimization of their performance requires process modeling based upon a detailed elementary step reaction mechanism verified for pure metals. For more complex active components such as Pt-promoted LaNiO 3 /Ce-Zr-O etc, elucidation of such detailed elementary kinetics would require too extensive research. This chapter presents a verification of more simple approach to modeling of both steady-state and start-up performance based upon using the rate constants for the reactions of methane selective oxidation and reforming reactions estimated for small separate units of monolithic catalysts in nearly isothermal conditions. Two types of honeycomb monolithic substrates based on corundum (a hexagonal prism with a side of 40 mm and triangular channels with wall thickness of 0.2–0.3 mm) or fechraloy foil (cylindrer 50 mm diameter, 200–400 cpsi, 20 μm foil thickness) were used. The metal surface is protected by a thin (∼10 μm) nonporous layer of corundum supported by the dust blasting. The active component comprised of mixed LaNiO 3 /Ce-Zr-La-O oxides (up to 15 wt%) and Pt (up to 0.5 wt.%) was supported via washcoating and/or impregnation procedures followed by drying and calcination.

Doped Nanocrystalline Pt-Promoted Ceria-Zirconia as Anode Catalysts for IT SOFC: Synthesis and Properties

Ceria-zirconia samples doped with Gd, Pr, Sm, or La cations were prepared via Pechini route and promoted by Pt. Effect of their real structure and surface properties (characterized by neutronography, EXAFS, XPS, FTIRS of adsorbed CO) on the mobility and reactivity of the lattice oxygen (by oxygen isotope exchange and CH 4 TPR) was analyzed. For the reaction of CH 4 steam reforming (SR), catalytic performance is determined both by Pt dispersion and lattice oxygen mobility. Ni-YSZ anodes promoted by these catalysts possess a stable and efficient performance in CH 4 SR in the 600-800°C range in stoichiometric feeds without coking.

Mobility and Reactivity of the Surface and Lattice Oxygen of Some Complex Oxides with Perovskite Structure

Mobility and reactivity of the surface and bulk oxygen of perovskite-like mixed oxides including lanthanum manganite (I) and ferrite (II) systems modified by Ca (I,II) and fluorine (I), as well as some Co, Fe-containing complex perovskites were considered. Combination of thermal analysis data, oxygen isotope exchange, O2 TPD, reduction by CO, H2 and CH4 TPR, were applied to characterize the accessible surface/bulk oxygen mobility and reactivity. Comparison of these results with earlier data on the real (defect) structure of these systems by TEM, EXAFS, XRD, FTIRS, SIMS allowed to elucidate factors determining the oxygen mobility and reactivity. A quantitative description of the experimental energetic spectrum of oxygen bound with regular and defect surface sites of perovskites was obtained by using the semiempirical Interacting Bonds method with a due regard for the surface face termination and relaxation. Pronounced effect of cation vacancies on the activation barrier for the oxygen migration in the perovskite lattice has been revealed.

Methane selective oxidation into syngas by the lattice oxygen in ceria-based solid electrolytes promoted by Pt

Abstract Nanocomposites based upon ceria doped by Zr, Zr+La or Sm with supported Pt nanoparticles efficiently convert methane into syngas by their lattice oxygen. In red-ox cycles with pure methane as reagent, the surface carbon build-up is observed, which is lower for Sm -doped samples possessing a higher surface and lattice oxygen mobility. When stoichiometric amounts of CO 2 or H 2 O are present in the feed, the catalysts efficiently operate in methane steam and dry reforming at high space velocities without deactivation.

Design of Anodes for IT SOFC: Effect of Complex Oxide Promoters and Pd on Activity and Stability in Methane Steam Reforming of Ni/YSZ (ScSZ) Cermets

Effect of fluorite-like or perovskite-like complex oxide promoters and Pd on the performance of Ni/YSZ and Ni/ScSZ cermets in methane steam reforming or selective oxidation by O 2 into syngas at short contact times was studied. Spatial uniformity of dopants distribution in composites was controlled by TEM combined with EDX, while the lattice oxygen mobility and reactivity was elucidated by CH 4 and H 2 TPR. Oxide promoters allow to operate even at stoichiometric H 2 O/CH 4 ratio by suppressing coke deposition through modification of Ni surface, while doping by Pd ensures reasonable performance at moderate (∼550 °C) temperatures required for Intermediate–Temperature Solid Oxide Fuel Cells (IT SOFC).