UNIDEF   23986
UNIDAD DE INVESTIGACION Y DESARROLLO ESTRATEGICO PARA LA DEFENSA
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
XANES study of the oxidation state of Cu, Ni and Ce cations in the Cu- Ni/ Ce0.9Zr0.1O2 cermet in reducing atmospheres
Autor/es:
L.M. TOSCANI; M.G. ZIMICZ; T. MARTINS; D.G. LAMAS; S.A. LARRONDO.
Reunión:
Encuentro; 25th Annual Users? Meeting (RAU); 2015
Resumen:
Solid Oxide Fuel Cells stand as a promising technology for efficient and sustainable energyproduction. In this context, \ce{Ce_{0.9}Zr_{0.1}O2} (Ni/ZDC) cermets are an excellentalternative to Ni/YSZ commercial anodes. The aim of this work is to study the effect ofpartial substitution of Ni by Cu in that cermet and to evaluate its performance in redox andcatalytic conditions. In situ XANES experiments using synchrotron radiation wereperformed at the Ce-LIII, Cu-K and Ni-K edges. Temperature programmed reduction (TPR)experiments were carried out in 5 mol.\% \ce{H2}/He atmospheres. Ce-LIII edge resultsshowed Ni/ZDC and CuNi/ZDC almost identical profiles up to 670°C, while the bimetallic sample presented higher reduction percentages up to 800°C. Both samples concluded the experiment with a total 40\% of Ce reduction. In the Ni-K edge, the bimetallic sample presented a lower reduction onset temperature and a higher proportion of Ni surface species exhibited in the larger area under first peak of TPR profile, with 100\% Ni reduction in both cases. Cu-K edge results showed a two step Cu reduction for the bimetallic sample. When the cermets are exposed to \ce{CH4}:\ce{O2}=2.6 ratio atmosphere, they exhibited low catalyst reduction percentages: 8\% Ni reduction for both cermets, 4\% and 2\% Ce reduction for cermets containing Ni and CuNi, respectively. The mass spectrometer signals of the exhaust gases during the experiments showed the production of both \ce{H2} and CO fortemperatures above 650°C.