Gradual Internal Reforming of Ethanol in Solid Oxide Fuel cells

AbstractElectrolyte (yttria-stabilised zirconia, YSZ) supported solid oxide fuel cells (SOFCs) were fabricated using spin coating of standard LSM cathode and Ni-YSZ cermet anode. A ceria-based catalytic layer was deposited onto the anode with a special current collector design. Such a single cell configuration allows operation by gradual internal reforming of direct carbon-containing fuels. First, the fabricated single cells were operated with hydrogen to determine the optimised conditions of fuel concentration and flow rate regarding faradaïc efficiency. Then, the fuel was switched to dry ethanol and the cells were operated for several hours (100h) with good stability. Post-operation electron microcopy analyses revealed no carbon formation in the anode layer. The results indicate that the gradual internal reforming mechanism is effective, opening up the way to multi-fuel SOFCs, provided that a suitable catalyst layer and cell design are available

Effect of Catalyst Layer and Fuel Utilization on the Durability of Direct Methane SOFC

International audienceSolid oxide fuels cells with and without anodic catalytic layer and specific anodic current collectors were developed in order to be fueled by dry methane. Due to the cell architecture integrating a 0.1wt% Ir-CGO catalyst layer onto the anode, platinum, gold and cupper screen-printed meshes were designed and optimized to ensure efficient current collection between the anode surface and the catalyst membrane. Current density and ageing in H2 and in pure dry CH4 respectively were compared to conventional pressed grid collecting systems. Similar performances were achieved using bulk grids or gold, platinum and copper screen-printed meshes. Operation in pure dry methane is compared with and without the catalytic layer as a function of the fuel utilization. It is demonstrated that long term operation is possible provided that sufficient faradic efficiency is achieved

Surface exchange polarization vs. gas concentration polarization in permeation through mixed ionic-electronic membranes

International audienc

HfO2-based electrolyte potentiometric oxygen sensors for liquid sodium

International audienc

Effect of Porous Layer on Oxygen Semi Permeation and Surface Exchange of CaTi0.9Fe0.1O3-δ Membranes

International audienceOxygen transport membranes are dense ceramic oxides that allow oxygen diffusion along a chemical potential gradient. CaTi0.9Fe0.1O3−δ (CTF) exhibits an interesting tradeoff between performance and stability; despite a lower oxygen flux, it exhibits a superior thermal, mechanical, and chemical stability. To optimize the performance of CTF, it is important to establish the rate-limiting step of oxygen transport mechanism, either surface oxygen exchange reactions, or bulk diffusion. We prepared CTF membranes with and without a porous layer. The limiting step was determined using the ratio between chemical potential drop of oxygen near the surface and across the bulk. We find that bare CTF membranes exhibit a mixed-control below 750 °C, changing to a bulk-limited process with increasing temperature. The porous layer mitigates surface limitation and increases the flux by 35% at lower temperature

Transport de l’oxygène dans des oxydes conducteurs mixtes

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Innovative Process for Reducing Emissions of Particulates

International @ AIR+PVEInternational audienceNon

A simple flash sintering setup under applied mechanical stress and controlled atmosphere

Most flash sintering experimental set-ups use dog bone-shaped specimen and DC current, which results in heterogeneously distributed densification and grain growth throughout the sample. This is the reason why only the sample's core characteristics after flash are taken into account. On the other hand, some recent procedures suggest the use of cylindrical pellets, which have some advantages compared to the traditional mode as the use of easily conformed samples and its final uniformity.\ud \ud Our new experimental set-up offers the possibility of atmosphere control and pressure application. Also the electrodes material change can be easily made when necessary. Shrinkage measurements and impedance spectroscopy are realized in situ and experimental parameters, as oven heating for example, can be varied to control microstructure changes

The influence of catalyst deposition onto dense membranes on catalytic properties

SSCI-VIDE+ATARI+KIC:PGEInternational audienceHigh temperature Solid Oxide Fuel Cells (SOFC) are promising energy conversion systems that can be operated directly on hydrocarbons (fossil or renewable sources) by using Ni-based anodes. In general, the hydrocarbon is mixed with steam, oxygen or carbon dioxide before feeding to the SOFC so that internal steam reforming, partial oxidation or dry reforming, respectively, could happen at the anode without carbon deposition. However, the endothermic nature of reforming reaction could induce thermal gradient and mechanical stress that dramatically lowers the lifetime of the SOFC.The system could be improved by operation with dry CH4. This could be realised by depositing a catalytic layer of Ir/CGO on conventional Ni cermet anode as shown in Fig. 11-4. SOFC provides water for steam reforming of CH4 on the Ir/CGO layer by Gradual Interna Reforming, while H2 produced from steam reforming is in turn used to operate the SOFC. Both reactions are self-sustained. In order to optimize the performance, it is necessary to better understand the catalytic behavior under real operating conditions, i.e., the influence of O2- transport from the cathode. In particular, the fundamentals of heterogeneous catalysis under polarization are to be fully understood. The present work shows that the membrane itself may influence, depending on its chemical nature, the reforming activity of the Ir/CGO catalyst