Papers by Keyword: SOFC Anode

Abstract: A Pd-Ni/La(Sr)CrO3-Ce(Sm)O2 composite anode showed good performance for solid oxide fuel cell reactions with dry CH4. Compositions of Pd and Ni in the Pd-Ni/La(Sr)CrO3-Ce(Sm)O2 composite anode affected the electrochemical oxidation catalysis of dry CH4. The Pd and Ni ratios from 50:50 to 75:25 were suitable for the oxidation. The Pd-Ni/La(Sr)CrO3-Ce(Sm)O2 composite anode showed the high tolerance to the carbon deposition under closed and open circuit conditions. A Pd-Ni/Ce(Sm)O2 catalyst showed very low catalytic activity for decomposition of dry CH4. A Pd-Ni/SiO2 catalyst showed very high catalytic activity for the decomposition of dry CH4 and a large amount of deposited carbon formed. The Pd-Ni particles on SiO2 were quite multifaceted from TEM-EDS observation. On the other hand, the Pd-Ni particles on Ce(Sm)O2 support had a spherical shape and doping of Ce and Sm was confirmed. This nature should inhibit the formation of particular plane that is essential for the carbon fiber formation. The detail function of Ce(Sm)O2 and La(Sr)CrO3 supports was discussed.

Abstract: The Ruddlesden-Popper (RP) compounds, Sr3Fe2O7-δ, RP n = 2, were synthesized by citrate gel method. Co was selected as dopant and substituted on Fe-site. Thermal decomposition behaviour and phase analysis of Sr3Fe2-xCoxO7-δ (x = 0 - 1.0) were characterized using Simultaneous TGA-DTA analyzer (STA) and X-ray diffractometer (XRD), respectively. The result showed a single phase obtained from the doped compositions after calcination at 1200°C. The microstructure of sintered compositions characterized using Scanning Electron Microscope (SEM) showed the porous structure as a requirement for anode material. The highest electrical conductivity in this work was obtained from Sr3FeCoO7-δ. The oxidation states of Co in Sr3Fe2-xCoxO7-δ compositions investigated by X-ray absorption near edge structure (XANES) technique were found to be +2 and +3 due to the Co K-edge energies existing between these of Co2+ and Co3+.

Abstract: Anodes composed of Ni-YSZ (yttria-stabilised zirconia) cermets are the key material to allow direct biofuel feeding to Solid Oxide Fuel Cell (SOFC) devices due to its internal reforming capability. The main challenge among these materials is related to carbon deposition poisoning effect when C-bearing fuels are feed. The work deals with these issues by alloying Ni with some metals like Cu to conform a multi-metallic anode material. Mechanical alloying (MA) at shaker mills is chosen as the route to incorporate the metal and ceramic powders in the anode material, also leading to better sintering behaviour. A projected cermet material is conceived where a third metal can be added based on two criteria: low Cu solubility and similar formation enthalpy of hydrides regarding Ni. Refractory metals like Nb, W and Mo, seems to fulfil these characteristics, as well as Ag. The MA resulted powder morphology is highly homogeneous showing nanometric interpolated metal lamellae. The sintering behaviour is investigated by conventional dilatometry as well as by stepwise isothermal dilatometry (SID) quasi-isothermal method to determine the sintering kinetic parameters. Based on these tools, it is found the Cu additive promotes sintering to obtain a denser anode and therefore allowing lower process temperatures. The consolidation is achieved through the sintering by activated surface (SAS) method allied to liquid phase sintering process, where the third metal additive also has influenced. The final cermet can be obtained at one sole process step, dispensing pore-forming additives and reduction treatments. The sintered microstructure demonstrates the material is homogeneous and possesses suitable percolation networks and pore structure for SOFC anode applications.

Abstract: A novel Ni-YSZ anode with interpenetrating phase composite (IPC) structure was developed using NiO-YSZ core-shell composite powder and evaluated in terms of microstructure, electrical conductivity, thermal expansion and flexural strength. In comparison to conventional anode, the anodic performance of IPC anode appeared to be more desirable for improving structural reliability of SOFC unit cells and stacks. This study reveals that the anodic performance of IPC anode can be readily tailored by controlling core-shell composite powder particles.