UNIDEF   23986
UNIDAD DE INVESTIGACION Y DESARROLLO ESTRATEGICO PARA LA DEFENSA
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
In -situ DXAS study of NiO/CeO2-Sm2O3 nanocomposites for IT-SOFC anodes under reducing and partial oxidation of methane conditions
Autor/es:
L.M. TOSCANI; D.G. LAMAS; M. C. A. FANTINI; M. G. ZIMICZ; S. A. LARRONDO; M. BELLORA; C. H. IRIART
Lugar:
Campinas
Reunión:
Simposio; 29th. RAU Annual Users Meeting LNLS.; 2019
Institución organizadora:
CNPEM/ LNLS
Resumen:
Fuel cells are promising devices for environmentally clean energy production by directly converting chemical energy into electricity. Among them, solid-oxide fuel cells (SOFCs) have the unique capability to use differentfuels such as hydrocarbons or H2. However, several issues have to be solved in order to improve theirefficiency and reduce their costs. The reduction of their working temperature, which is typically around 900-1000°C, is one of the most important issues. For this reason, extensive research has been devoted todevelop novel materials for intermediate-temperature SOFCs (IT-SOFCs). CeO2-based anodes have provento exhibit excellent catalytic properties. Besides, these materials are mixed ionic/electronic conductors(MIECs) under reducing atmosphere and, therefore, fuel oxidation can take place on its entire surface, whileit only occurs in the [anode/electrolyte/gas] interphase (triple-phase boundaries) for electronic conductors.In recent works, we investigated the performance of nanostructured CeO2-based anodes for IT-SOFCs [1].Nanomaterials are not employed in conventional SOFCs since grain growth is expected to occur at hightemperature, but their use in IT-SOFCs is currently under evaluation. Anodes based on nanostructuredMIECs are very interesting because the number of active sites for fuel oxidation is expected to increasedramatically. The aim of this work is to take further insight into the catalytic properties of Ni/CeO2-Sm2O3 composite under reducing and partial oxidation of methane (POM) reaction condition [1-3]. Dispersive X-ray absorption spectroscopy (DXAS) technique was used in the Ce LIII and Ni K absorption edges in order todetermine the oxidation states of cerium and nickel cations in the reaction conditions prevailing in the catalytic studies. The influence of the sample morphology was evaluated by analyzing samples subjected to different thermal treatments, finding that the samples calcined at lower temperatures had a higher reducibility in both the Ni and Ce and the reduction process is completed at a lower temperature. However, all the studied materials exhibit similar performance under partial oxidation of methane conditions.