FRANCISCO NOBUO TABUTI

FRANCISCO NOBUO TABUTI

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Steam reforming catalytic layer on anode-supported and metal-supported solid oxide fuel cells for direct ethanol operation
2023 - MACHADO, MARINA; TABUTI, F.; PIAZZOLLA, F.; MORAES, T.; ABE, R.; GUIMARAES, R.M.; MIURA, Y.; FUKUYAMA, Y.; FONSECA, F.C.
A catalyst based on lanthanum chromite with exsolved metallic ruthenium nanoparticles (LaCrO3-Ru) was applied as a catalytic layer for internal ethanol steam reforming of anode-supported and metal-supported solid oxide fuel cells. The metal support exhibits limited catalytic properties for the ethanol steam reforming reaction. Thus, the LaCrO3-Ru catalysts were optimized for operating temperatures in the 600-700 °C range to promote stable ethanol reforming. The catalytic layer had no significant impact on the electrochemical properties of the fuel cell, and samples with and without the catalytic layer exhibited similar performance in hydrogen. Initial durability tests with LaCrO3-Ru layer have shown that the catalytic layer plays a crucial role in the stability of the metal-supported fuel cell under ethanol.
W-doped Lanthanum Molybdenum Oxide/Lithium-Sodium-Potassium Carbonate Composite Membranes for Carbon Dioxide Permeation
2023 - MEDINA, MIDILANE S.; CARVALHO, SABRINA G.M.; TABUTI, FRANCISCO N.; MUCCILLO, ELIANA N.S.; FONSECA, FABIO C.; MUCCILLO, REGINALDO
Single-phase tungsten-doped lanthanum molybdenum oxide (La2MoWO9) ceramic powders were synthesized using the complex polymerization technique. Porous ceramic pellets were obtained by thermally removing graphite, which served as a pore former. The porous pellets were then impregnated with molten eutectic lithium-sodium-potassium carbonates. The energy dispersive X-ray analysis and scanning electron microscopy (FEG-SEM) images of the external and fracture surfaces of the La2MoWO9-(Li,Na,K)2CO3 composite dual-phase membrane revealed the percolation of the carbonate mixture through the pores. Electrochemical impedance spectroscopy measurements conducted at temperatures below and above the melting point of the eutectic carbonate composition demonstrated the contributions of oxygen and carbonate ions to the ionic conductivity of the dual membrane. The electrical conductivity of the carbonate ions within the membrane was continuously monitored for over 1300 h with negligible degradation, implying that the membrane could be used for long-term monitoring of CO2 without aging effects. A comparison of FEG-SEM images taken before and after this endurance test suggested minimal fouling, indicating that the membrane could potentially replace similar zirconia- and ceria-based composite membranes.
Exploring the stability of direct ethanol solid oxide fuel cells at intermediate temperature
2021 - FONSECA, F.C.; TABUTI, F.; MORAES, T.; ABE, R.; GUIMARAES, R.M.; MIURA, Y.; FUKUYAMA, Y.
Anode supported fuel cells were tested in direct (no water added) bioethanol at intermediate temperature (600°C and 700°C). The standard fuel cell has reasonable short-term stability under dry ethanol if current is continuously drawn at a minimum fuel utilization factor at 700ºC. However, the YSZ/Ni anode develops carbon deposits as inferred from post fuel cell test analyses and fixed bed steam reforming catalytic tests at 600°C. Thus, an active catalytic layer with tailored properties for ethanol internal reforming was studied. Initial tests investigated the Ir/gadolinium-doped ceria catalysts previously proven stable at 850°C. The main results have shown that the catalytic layer has no significant effect on the performance of the fuel cell running under hydrogen. The use of a ceria-based catalytic layer has enhanced the stability of the fuel cell under dry ethanol at 700°C, but stable operation at 600°C requires the development of more active catalyst.
The role of the ceria dopant on Ni / doped-ceria anodic layer cermets for direct ethanol solid oxide fuel cell
2021 - SILVA, A.A.A. da; STEIL, M.C.; TABUTI, F.N.; RABELO-NETO, R.C.; NORONHA, F.B.; MATTOS, L.V.; FONSECA, F.C.
The effect of ceria dopant aiming at stability in Ni/doped-ceria anodic layers for direct ethanol solid oxide fuel cells (SOFC) was studied. Solid solutions of ceria doped with Y, Gd, Zr, or Nb (10 mol%) impregnated with NiO were tested in a fixed bed reactor for ethanol conversion reactions and for direct (dry) ethanol SOFC. The ceria dopant showed a marked effect on both the catalytic and the electrical transport properties of the ceramic support. Catalytic activity data revealed that the studied materials deactivate in ethanol decomposition reaction but are stable for ethanol steam reforming. Thus, feeding dry ethanol to the SOFC with a Ni/doped-ceria anodic catalytic layer evidenced that water produced from the electrochemical hydrogen oxidation provides steam for the internal reforming resulting in great stability of the fuel cells tested during ~100 h. The combined catalysis and SOFC results demonstrate Ni/doped-ceria is as candidate anode layer for stable SOFC running on bioethanol.
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.