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Abstract: Hydrogen sulfide, usually considered to be an anode catalyst poison, strongly promotes methane oxidation over sulfur resistant catalysts. The role of H2S in oxidation of sour CH4 feed over a sulfur resistant SOFC anode catalyst at 850°C has been determined through thermodynamic and experimental studies. The anode material was an intimately mixed 50/50 mass ratio composite of La0.4Sr0.6TiO3−δ and YSZ. The power density improved dramatically from 2mWcm−2 with pure CH4 as fuel to more than 450mWcm−2 for CH4 containing 20% H2S. However, H2S was not the only fuel converted, and its interaction with CH4 was the key factor in enhancement of performance. The anode effluent gas mixture included H2S, SO2, H2 and CS2 consistent with thermodynamic predictions. The role of H2S in the CH4 oxidation mechanism was determined, and showed that CH4 and H2S must be considered together as a fuel and not as two separate fuels. The types of electrochemical reactions that occurred in the fuel cell were strongly dependent on potential. [Copyright &y& Elsevier]

Abstract: Whereas Ce0.9Sr0.1Cr0.5V0.5O3 is an active fuel cell anode catalyst for conversion of only the H2S content of 0.5% H2S–CH4 at 850°C, inclusion of 5wt% NiO to form a composite catalyst enabled concurrent electrochemical conversion of CH4. A fuel cell with a 0.3mm thick YSZ membrane and Ce0.9Sr0.1Cr0.5V0.5O3 as anode catalyst had a maximum power density of 85mWcm−2 in 0.5% H2S–CH4 at 850°C, arising only from the electro-oxidation of H2S. Using a same thick membrane, promotion of the anode with 5wt% NiO increased the total anode electro-oxidation activity to afford maximum power density of 100mWcm−2 in 0.5% H2S–CH4. The same membrane provided 30mWcm−2 in pure CH4, showing that the incremental improvement arose substantially from CH4 conversion. Performance of each anode was stable for over 12h at maximum power output. XPS and XRD analyses showed that an increase in conductivity of Ce0.9Sr0.1Cr0.5V0.5O3 in H2S-containing environments resulted from a change in composition and structure from the tetragonal oxide to monoclinic Ce0.9Sr0.1Cr0.5V0.5(O,S)3. [Copyright &y& Elsevier]

Abstract: The stability and activity in 0.5% H2S–CH4 of Ce0.9Sr0.1VO3 and Ce0.9Sr0.1VO4 anode materials for H2S-containing CH4 fueled SOFCs have been determined. XRD showed that Ce0.9Sr0.1VO4 was reduced when the fuel gas was 0.5% H2S–CH4, while Ce0.9Sr0.1VO3 remained stable over 24h at 950°C. Electrochemical tests in 0.5% H2S–CH4 showed stable performance at 950 and 800°C for cells comprising Ce0.9Sr0.1VO3|YSZ|Pt. Comparison of fuel cell performances using 0.5% H2S–CH4, 0.5% H2S–N2 and 5% H2S–N2 as feeds showed that Ce0.9Sr0.1VO3 was not active for oxidation of methane, but highly active for conversion of H2S. Electrochemical impedance results were consistent with the finding that the anode was activated only in an environment that contained H2S. Conductivity measurements showed there was an increase in conductivity in H2S-containing environments, and that this increase resulted from a change in composition and structure from the oxide to monoclinic Ce0.9Sr0.1V(O,S)3, as evidenced by XPS and XRD analyses. [Copyright &y& Elsevier]

Abstract: Undoped BaTiO3 perovskite oxide is more effective than SrTiO3 and La2Ti2O7 oxide as anode catalyst in SOFC fueled with H2S-containing methane. Electrochemical performance, impedance spectroscopy and other characterizations show that pure BaTiO3 is a good anode catalyst for conversion of methane in SOFC, especially in H2S-containing atmospheres. Compared with SrTiO3 and La2Ti2O7 samples, the BaTiO3−based fuel cell has higher resistance to carbon deposition, better electrochemical performance and much higher stability during long term operation. A maximum power density of 135 mW cm−2 was achieved at 900 °C with 0.5% H2S–CH4 in a fuel cell having a 300 μm thick YSZ electrolyte. High catalytic activity for methane conversion, mixed electronic and ionic conductivity, and the surface basicity of BaTiO3 unexpectedly provides promising performance as anodes in SOFC. [Copyright &y& Elsevier]

Abstract: Ethane and electrical power are co-generated in proton ceramic fuel cell reactors having Cr2O3 nanoparticles as anode catalyst, BaCe0.8Y0.15Nd0.05O3−δ (BCYN) perovskite oxide as proton conducting ceramic electrolyte, and Pt as cathode catalyst. Cr2O3 nanoparticles are synthesized by a combustion method. BaCe0.8Y0.15Nd0.05O3−δ (BCYN) perovskite oxides are obtained using a solid state reaction. The power density increases from 51mWcm−2 to 118mWcm−2 and the ethylene yield increases from about 8% to 31% when the operating temperature of the solid oxide fuel cell reactor increases from 650°C to 750°C. The fuel cell reactor and process are stable at 700°C for at least 48h. Cr2O3 anode catalyst exhibits much better coke resistance than Pt and Ni catalysts in ethane fuel atmosphere at 700°C. [ABSTRACT FROM AUTHOR]

Abstract: Cu surface modified nickel foam is obtained by heating copper coated nickel foam in a reducing atmosphere. La0.75Sr0.25Cr0.5Mn0.5O3−δ (LSCM) perovskite oxide is prepared using a sol–gel combustion method. The modified foams and LSCM powders exhibit excellent resistance to carbon deposition in syngas at high temperatures. Furthermore, Cu modified foams show better mechanical strength compared to bare Ni foam, which readily cracks after exposure to syngas at high temperature. LSCM retains its perovskite structure during exposure to syngas or carbon monoxide at 900 °C for 10 h. Cu surface modified Ni foam current collector demonstrates good chemical compatibility with LSCM in syngas atmosphere at high temperature. Syngas solid oxide fuel cells (SOFCs) are assembled using Cu modified Ni foam anode current collector, LSCM anode catalyst, YSZ electrolyte, and porous Pt cathode. The present fuel cell provides similar power density to one with gold anode current collector and has excellent stability during operation at 900 °C. [ABSTRACT FROM AUTHOR]