Design of Anodes for IT SOFC: Effect of Complex Oxide Promoters and Pd on Activity and Stability in Methane Steam Reform
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0972-AA03-06
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 Vladislav A. Sadykov1, Natalia V. Mezentseva2, Rimma V. Bunina2, Galina M. Alikina2, Anton I. Lukashevich2, Vladimir A. Rogov2, Ella M. Moroz2, Vladimir I. Zaikovskii2, Arcady Ishchenko2, Oleg F. Bobrenok3, Alevtina Smirnova4, John Irvine5, and Oleksandr Vasylyev6 1 Heterogeneous catalysis, Boreskov Institute of Catalysis, pr. Lavrentieva, 5, Novosibirsk, 630090, Russian Federation 2 Boreskov Institute of Catalysis, Novosibirsk, 630090, Russian Federation 3 Institute of Thermophysics SB RAS, Novosibirsk, 630090, Russian Federation 4 University of Connecticut, Storrs, CT, 06269 5 University of St Andrews, Fife, KY169ST, United Kingdom 6 Institute for Problems of Materials Science, Kyiv, 03142, Ukraine
ABSTRACT Effect of fluorite-like or perovskite-like complex oxide promoters and Pd on the performance of Ni/8YSZ and Ni/ScSZ anode materials in CH4 steam reforming (SR) or selective oxidation (SO) by O2 into syngas was studied. The spatial uniformity of dopants distribution in composites was controlled by TEM combined with EDX analysis, while the lattice oxygen mobility and reactivity were estimated by CH4 and H2 temperature-programmed reduction (TPR). The oxide promoters suppress the coke deposition even at stoichiometric H2O/CH4 ratio, while doping by Pd ensures a good performance at moderate (~550 oC) temperatures required for the Intermediate –Temperature Solid Oxide Fuel Cells (IT SOFC) operation. INTRODUCTION Design of anode materials for IT SOFC able to efficiently operate in methane/steam feeds without coking represents important but demanding problem. A promising approach consists in doping Ni/YSZ (ScSZ) anodes by fluorite-like or perovskite-like oxides with a high oxygen mobility [1-3], which is expected to suppress coking due to more efficient activation of oxidant (H2O) and a higher oxygen flux from the electrolyte phase to the Ni surface. To increase the middle-temperature (600-700 oC) performance of SOFC anodes in CH4 SR, small amounts of Pt group metals are added [2]. The effect of these promoters depends on various factors such as the chemical composition of electrolyte and porosity of NiO/electrolyte composites as precursors for the cermet anodes. This work presents the results of comparative study of the effect of perovskite and fluorite oxides doping combined with Pd supporting on the properties of Ni/YSZ and Ni/ScSZ anode cermet materials. EXPERIMENTAL DETAILS Two types of composite powders were used in this study. The Composite I was prepared from 50 wt. % NiO (Novamet, US) and Sc0.1Ce0.01Zr0.89O2-y (DKKK, Japan) powders. Composite II was comprised of the mixture of NiO (60 wt.%) and Y0.08Zr0.92O2-y (Russian sources).
The powders were pressed into pellets, sintered at 1200 oC for 2 hours, crushed and ball milled to micron-sized powders as described earlier [4] resulting in the specific surface area of ~1 m2/g for Composite I and 5 m2/g
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