Steam Reforming of Methane on Ru and Pt Promoted Nanocomposites for SOFC Anodes
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1217-Y03-11
Steam Reforming of Methane on Ru and Pt Promoted Nanocomposites for SOFC Anodes Natalia Mezentseva1, Galina Alikina1, Rimma Bunina1, Vladimir Pelipenko1, Arcady Ishchenko1, Alevtina Smirnova3, Oleg Smorygo4, Vladislav Sadykov1,2 1 Boreskov Institute of Catalysis, Novosibirsk, 630090, Russia 2 Novosibirsk State University, Novosibirsk, 630090, Russia 3 Eastern Connecticut State University, Willimantic, CT, USA 4 Powder Metallurgy Institute, Minsk, 220005, Belarus ABSTRACT Nanocomposite cermet materials comprised of NiO/YSZ (20-90 wt. %) co-promoted with SmPrCeZrO or LaPrMnCrO complex oxides and Pt, Pd or Ru were synthesized by Pechini method. These materials were characterized by BET, TEM with EDX, and CH4 TPR. The catalytic properties were studied for the steam reforming (SR) of CH4 at short contact times. Factors controlling performance of these composites in CH4 SR (Ni content, interaction between components in composites as dependent upon their chemical composition) were determined. Rupromoted composite supported on Ni-Al foam demonstrated a high (up to 75%) methane conversion at 650oC in the feed containing 20% CH4 and 40% H2O in Ar. INTRODUCTION Design of materials able to efficiently perform steam reforming of CH4 or biofuels without coking in the 500-600oC range is an important problem for the hydrogen energy field including internal reforming of fuels on Solid Oxide Fuel Cells (SOFC) anodes. A promising approach consists in synthesis of nanocomposites comprised of components able to efficiently activate CH and C-C bonds in the fuel molecules (Ni, Pt, Ru, and Pd) combined with complex oxides with a high oxygen mobility required to suppress coking [1]. While broad application of Pt group metals in SOFC anodes is limited by their high cost, inexpensive Ni in traditional Ni/YSZ cermets is rapidly deactivated by coking during SR CH4 in the stoichiometric feeds [2, 3]. This problem can be solved by decreasing the Ni/complex oxide ratio in composites and supporting Pt (Pd, Ru) on the surface of Ni particles forming alloys more stable to coking [4, 5]. To provide heat transfer in SOFC anodes, active components with decreased Ni content can be supported on metal substrates with a high thermal conductivity [6-8]. This paper presents results of research aimed at elucidating the effect of Ni content, complex oxides and Pt group metals additives in nanocomposite active components as well as their supporting on compressed foam Ni-Al substrate [8] on the activity and coking stability in CH4 SR in feeds with a small excess of steam. EXPERIMENTAL The nanocomposites comprised of perovskite (La0.8Pr0.2Mn0.2Cr0.8O3) or fluorite (Sm0.15Pr0.15Ce0.35Zr0.35O2) oxides in combination with NiO and YSZ (Y0.08Zr0.92O2-δ) (Table 1) were synthesized using earlier described one-pot Pechini method [9-11]. Here, YSZ powder was
dispersed in mixed water solution of metal nitrates with addition of citric acid and ethylene glycol. After evaporation, the solid residue was decomposed in air at 500οC and calcined at 800οC for 2 h. To
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