Nanocomposite catalysts for internal steam reforming of methane and biofuels in solid oxide fuel cells: Design and performance

Nanocomposite catalysts comprised Ni particles embedded into the complex oxide matrix comprised Y- or Sc-stabilized zirconia (YSZ, ScCeSZ) combined with doped ceria–zirconia oxides or La–Pr–Mn–Cr–O perovskite and promoted by Pt, Pd or Ru were synthesized via different routes (impregnation of YSZ or NiO/YSZ composites with different precursors, one-pot Pechini procedure). Both composition and preparation procedure determining degree of interaction between components of composites were found to strongly affect performance of nanocomposites in steam reforming of methane at short contact times as well as their stability to coking in stoichiometric feeds. Temperature-programmed reduction of composites by CH4 followed by temperature-programmed oxidation by H2O revealed more efficient dissociation of CH4 on promoted composites yielding loose surface CHx species more easily removed by water as compared with unpromoted composites. Best active components highly active and stable to coking were supported as thin layers on different substrates (Ni/YSZ anode platelets, refractory dense/porous metal alloys, cermet or corundum monolithic carriers). These structured catalysts demonstrated high efficiency and stability in the reactions of steam reforming of methane and oxygenates (ethanol, acetone) in pilot-scale reactors.