Electrochemical Performance And Carbon Deposition Resistance Of Solid Oxide Fuel Cells Fueled With Biosyngas From Sludge Pyrolysis

Solid oxide fuel cells(SOFCs), an electrochemical device that can directly convert chemical energy in fuel to electricity, offers tremendous promises such as fuel flexibility, high energy conversion efficiency and wide application. A large volume of biosyngas could be released from microwave-induced pyrolysisof sewage sludge. Its main compositions are H2 and carbonaceous gas. SOFCs could run on H2 in the biosyngas from sludge pyrolysis with high efficiency. However, carbon deposition resulted from the carbonaceous gas could be easily formed in the SOFCs anode during electricity generation. They compromise the SOFC s fed with the biosyngas for electricity generation.This study was particularly focused on the carbon deposition in the SOFC s anode chamber with the biosyngas feeding. The simulated biosyngas was employed in this investigation. Electrochemical performance and the carbon deposition of conventional Ni-YSZ anode-supported SOFCs fabricated by tape casting in the simulated biosyngas were first investigated. Secondly, the Ni-YSZ anode was modified by silver impregnation in a hot Ag NO3 solution, the SOFCs with the modified anode were studied on the electrochemical performance and the carbon deposition resistance behaviors. Finally, the electrochemical performance and the carbon deposition resistance of the SOFCs with an novel Nb doped La0.9Ca0.1Fe O3-δ anode structured by impregnation technology were performed.The electrochemical performance and the carbon deposition of Ni-YSZ anode supported SOFCs in the simulated biosyngas were studied. The electrochemical performance results showed that the biosyngas is an excellent fuel for the elect ricity generation in the SOFCs with Ni-YSZ anode. The maximum power density(MPD) of the cell in the simulated biosyngas could reach up to 90.5% of the same cell in H2. When the galvanostatic experiment was performed, there was a descent phase of terminal voltage at the initial stage due to the carbon deposition. A low terminal voltage was displayed at the followed long-term stability. In addition, the carbon deposition in the SOFCs system was mainly located on the junction of anode surface and the anode chamber identified by scanning electron microscope(SEM).The performance and the carbon resistance of Ag/Ni-YSZ anode supported SOFCs in the simulated biosyngas were investigated. The results indicated that not only the electrochemical performance of the cell with Ag/Ni-YSZ anode was increased in H2, but also was more resistant to the carbon deposition with CH4 feeding. There was a minor effect on electrochemical performance of the modified cell in the simulated biosyngas. When the cell was operated at a constant current density, the descent phase of the terminal voltage got shorter and the terminal voltage was raised during the stability term. The thickness of the carbon deposition in the anode were decreased. The main reason of the Ag modified Ni-YSZ anode with the carbon resistance was that the high catalytic activity of Ni particles to hydrocarbon was limited by the Ag particles adding.The performance and the carbon resistance of SOFCs with Nb doped La0.9Ca0.1Fe O3-δ(LCF) anode in the simulated biosyngas were concentrated. Nb doping can stabilize the LCF in the reducing atmospheres up to 900 °C identified by X-ray diffraction(XRD).The chemical stability of the Nb doped LCF is attributed to the constrained valence stability of Fe3+ to Fe2+ from Nb5+. Additionally, the Nb doped LCF anode has high catalytic activity towards H2 and CO while low one in CH4. Meanwhile, the La0.9Ca0.1Fe0.9Nb0.1O3-δ(LCFNb0.1) was identified as the optimized anode material. The MPD of the cell with LCFNb0.1 anode was 0.336 W/cm2 in the biosyngas at 750 °C. The descent phase of the terminal voltage was short with little decrease and the ratio of the power density in the simulated biosyngas to in H2(WBio/WH2) was 72.5% during thegalvanostatic experiment. Moreover, the carbon deposition in the LCFNb0.1 anode was greatly suppressed by its selective catalytic oxidation of component in the simulated biosyngas.In summer, the underlying parameter and mechanism of the carbon deposition in the Ni-YSZ anode chamber was studied with the simulated biosyngas feeding. The stability of the carbon resistance for the Ni-YSZ was greatly improved by Ag modification. The carbon deposition in the anode with the simulated biosyngas feeding could be overcomed by the novel LCFNb0.1 anode employment. Meanwhile, the performance of the SOFCs with LCFNb0.1 anode was encouraging. Some significance of theory and application were provided by this subject on the performance of the SOFCs and the carbon resistance in the anode with the biosyngas feeding.