Triode Operation for Enhancing the Performance of H2S-PoisonedSOFCs for CH4 Steam Reforming
| Autor: | Boreave, A., Sapoutzi, M., Tsampas, N., Chunhua, Z., Retailleau-Mevel, L., MONTINARO, D., Vernoux, P. |
|---|---|
| Přispěvatelé: | IRCELYON, ProductionsScientifiques, IRCELYON-Catalytic and Atmospheric Reactivity for the Environment (CARE), Institut de recherches sur la catalyse et l'environnement de Lyon (IRCELYON), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC) |
| Jazyk: | angličtina |
| Rok vydání: | 2015 |
| Předmět: | |
| Zdroj: | 66th Annual Meeting of the International Society of Electrochemistry 66th Annual Meeting of the International Society of Electrochemistry, Oct 2015, Taïpei, Taiwan |
| Popis: | SSCI-VIDE+CARE+ABO:LRE:PVE; International audience; Performances of Solid Oxide Fuel Cells (SOFCs) were investigated in triode operation mode under methane steam reforming in presence of H2S. Both the catalytic performances for methane steam reforming and the electrochemical properties of the anode are drastically dropped by the presence of H2S impurities introduced through the use of fuels such as natural gas. Indeed, typically 1-30 ppm H2S content can be observed in natural gas. Conventional Ni-based cermet anode exhibit strong deactivation when exposed to few ppm H2S. This loss is generally attributed to sulfur adsorption on Ni active sites.Triode operation is a novel approach for enhancing the performances of fuel cells and electrolysers. This concept is based on the introduction of a third electrode (auxiliary electrode) in addition to the conventional anode and cathode. This auxiliary electrode is located at the cathode side, as shown in the following figure: Electrodes were deposited by screen printing of commercial powders (Marion Technologies) on YSZ discs (Dynamic Ceramic, 8% mol Y2O3-ZrO2) with diameter of 20 mm and 1.6 mm thickness. The anode electrode was a Ni/GDC film of 40 µm thickness and a surface area of 1.76 cm2 and was sintered at 1250°C for 2 hours. The cathode and the auxiliary electrodes were composed of LSM oxides (La0.65Sr0.35MnO3 - fuel Cell Materials, LSM35) mixed with YSZ (Tosoh). The cathode was a ring shaped electrode at the periphery of 0.93 cm2 surface area, and the auxiliary was a circular dot electrode of 0.31 cm2 surface area at the center of the cathode but separated from the cathode. They were sintered at 1150°C for 2 hours.To study the performances of the bottom cells, we have used a test rig (ProboStat, NorECs, Netherland). The sealing between the anodic and cathodic compartments was ensured by a gold ring which was annealed at 1040°C for 4 days under air. For current collection, Pt meshes were used for cathode and auxiliary while Ti mesh, catalytically inactive,was used for anode. Prior to the experiments, the catalysts were reduced under pure H2 at 900oC for 2 hours. The effect of the addition of H2S in the reaction mixture has been investigated (1 ppm of H2S/He, 2%CH4/He â Air Liquide, 5% H2O added with a thermostated water saturator regulated at 33 °C) under 200cc/min flow while cathode and auxiliary were exposed under synthetic air (Linde 99,995%). The products of the reaction were analyzed by using a Hiden Analytical HPR20 quadripole mass spectrometer.H2S poisoning was followed in open circuit mode, in fuel cell mode and in triode operation mode at 900°C. Triode operation cannot avoid or limit the catalytic degradation of the SOFC cell exposed to 1 ppm H2S but can maintain higher anodic electrochemical performances. This confirms that active sites for catalytic conversion (methane steam reforming) and those for electrochemical oxidation of hydrogen are not the same. The cell performances loss is mainly attributed to the degradation of the catalytic activity, then decreasing the concentration of electroactive species, i.e. hydrogen. Triode operation can slightly compensate the deactivation of the catalytic sites most probably with a local production of H2, from H2O electrolysis. Some specific triode operations can be found to achieve a thermodynamic efficiency close to the unity to avoid any energy overconsumption.Acknowledgements: this work was financed by the EU 7th Framework Program, Fuel Cells and Hydrogen Joint Technology Initiative, under the frame of the T-CELL project (grant agreement 298300). |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|