FRANCISCO NOBUO TABUTI

FRANCISCO NOBUO TABUTI

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Development of ceria-based direct ethanol intermediate-temperature solid oxide fuel cell
2018 - TABUTI, FRANCISCO N.; PEREIRA, VICTORIA B.; PIAZZOLLA, FERNANDO; FONSECA, FABIO C.
Solid oxide fuel cells (SOFCs) have several advantages over traditional energygenerating devices. A key property is the possibility of using various fuels such as natural gas and ethanol, which are strategic for Brazil. This study addresses two aspects that need to be improved in SOFC: (a) the high operating temperature of the cell that brings several problems for assembly and operation of a power system, and (b) the deactivation of the cell due to the deposition of carbon on the surface of the nickel anode when the cell is fed with carbon-containing fuels. The properties of ceria-based/Ni cermets both as the anode material and as the catalytic layer for bio-ethanol fueled SOFC with yttria-stablilized zirconia electrolyte were investigated. Ceria-based/Ni cermets were studied as the catalytic layer deposited onto the standard yttria-stabilized zirconia/Ni anode for direct ethanol SOFCs. Properties of both Zr- and Nb-doped (10 mol%) ceria / Ni (15 vol%) cermets were investigated as the catalytic layer in direct ethanol SOFCs. Electrolyte-supported fuel cells with doped-ceria /Ni catalytic layer were tested for ~100 hours under (dry) ethanol. Fuel cells using the different ceria/Ni cermets showed excellent stability on ethanol. The promising results obtained with ceria-based anodes for SOFC of ethanol motivated the development of ceriabased SOFCs. Thus, intermediate-temperature SOFCs using doped-ceria electrolytes have been tested at 600 °C using hydrogen. Preliminary results show that direct ethanol SOFC are promising devices for efficient energy conversion at intermediate temperatures.
Anodic layers based on doped-Ceria/Ni cermet for direct ethanol fuel cells
2017 - SILVA, A.A. da; TABUTI, F.N.; MATTOS, L.V.; STEIL, M.C.; NORONHA, F.B.; FONSECA, F.C.
Ceria-based/Ni cermets were studied as the catalytic layer deposited onto the standard yttria-stabilized zirconia/Ni anode for direct ethanol solid oxide fuel cells. The influence of the dopant on both Zr- and Nb-doped (10 mol%) ceria and pure ceria was investigated on the properties of cermets with Ni ~15% volume fraction. Electrolyte-supported fuel cells with ceria-based/Ni catalytic layer were tested for ~100 hours under (dry) ethanol. Fuel cells using the different ceria/Ni cermets showed excellent stability on ethanol, irrespectively of the different properties of the ceramic phase of the catalytic layer. Fuel cells results confirmed that the studied ceria-based cermets are stable catalysts towards ethanol steam reforming.
Optimization of spin-coated electrodes for electrolyte-supported solid oxide fuel cells
2017 - NOBREGA, SHAYENNE D. da; MONTEIRO, NATALIA K.; TABUTI, FRANCISCO; FLORIO, DANIEL Z. de; FONSECA, FABIO C.
Electrodes for electrolyte-supported solid oxide fuel cells (SOFC’s) were fabricated by spin coating. Strontium- doped lanthanum manganite (LSM) cathode and nickel yttria-stabilized zirconia cermet anodes were synthesized and processed for enhanced deposition conditions. The influence of electrode microstructural parameters was investigated by a systematic experimental procedure aiming at optimized electrochemical performance of single cells. Polarization curves showed a strong dependence on both electrode thickness and sintering temperature. By a systematic control of such parameters, the performance of single cells was significantly enhanced due to decreasing of polarization resistance from 26 Ω cm² to 0.6 Ω cm² at 800°C. The results showed that spin-coated electrodes can be optimized for fast and cost effective fabrication of SOFCs.
Influence of microwave-assisted hydrothermal treatment on the properties of nickel oxide-zirconia based composites
2016 - PINHEIRO, L. B.; TABUTI, F.N.; MARTINELLI, A.E.; FONSECA, F.C.
Nickel/gadolinium-doped ceria anode for direct ethanol solid oxide fuel cell
2014 - AUGUSTO, BRUNO L.; NORONHA, FABIO B.; FONSECA, FABIO C.; TABUTI, FRANCISCO N.; COLMAN, RITA C.; MATTOS, LISIANE V.
This report investigates the properties of nickel/gadolinium-doped ceria (Ni/GDC) as anode material for bio-ethanol fueled SOFC. The Ni/GDC cermets with 18 and 44 wt.% Ni were prepared by a hydrothermal method. Ethanol decomposition, steam reforming, and partial oxidation of ethanol were studied using a fixed-bed reactor at 1123 K. Carbon was formed only under dry ethanol for both catalysts. The addition of water or oxygen to the feed inhibited the formation of carbon. Ni/GDC was used as the anode current collector layer and as a catalytic layer in single cells tests. No deposits of carbon were detected in single cells with Ni/GDC catalytic layer after 50 h of continuous operation under direct (dry) ethanol. This result was attributed to the catalytic properties of the Ni/GDC layer and the operation mechanism of gradual internal reforming, in which the oxidation of hydrogen provides the steam for ethanol reforming, thus avoiding carbon deposition.