No abstract

No abstract

Applying a synthesis procedure that promotes alloy formation, highly-dispersed alumina-supported Pt-Pd catalysts spanning the Pt-rich half of the composition range were prepared, aged under oxygen-rich hydrothermal conditions, and characterized by CO chemisorption, XRD, and TEM. Anomalously large particles, typical of pure Pt catalysts treated under such conditions, were not found in any of the Pd-containing catalysts, and the extent of particle coarsening due to aging was found to decrease with increasing Pd content. Alloying appears to have little effect on the NO oxidation turn-over frequency, which increases with decreasing dispersion.

The feasibility and benefits of using an oxygenated fuel for solid oxide fuel cell (SOFC) operation were explored using dimethyl ether (DME). A model for the flow tube chemistry was used to predict DME gas-phase decomposition kinetics and species concentration profiles for temperatures ranging from 550 to 750°C. The predictions, which were in good agreement with mass spectral measurements, showed that in the absence of a fuel cell DME decomposed primarily into equal amounts of H2, CH4, and CO above about 675°C. The same decomposition species were observed in catalytic reaction experiments at Ni-based anodes, but the mole fractions of the decomposition gases were much higher, between 550 and 650°C. Current-voltage measurements were made using SOFCs with 100 μm thick yttria-stabilized zirconia electrolyte supports, false(normalLa,normalSrfalse)false(normalCo,normalFefalse)O3 cathodes, and 50 vol % Ni-based anodes. Maximum power densities for SOFCs supplied directly with DME fuel were 0.10 and 0.21W/cm2 at 600 and 700°C, respectively. No carbon deposition was observed in cells operated at temperatures up to 700°C. © 2002 The Electrochemical Society. All rights reserved.