Selection of Completed Projects
 
1. Anode supported SOFC with thermal cycling and redox stability (2002-2003).

The objective of this project was to produce small anode supported electrolyte (ASE) bt cells (diameter 40 mm, 0.15-0.4 mm thick AS, 5-10 um electrolyte) that resist both to thermal cycling and especially redox cycling conditions. The project was supported by the Swiss Federal Office of Energy (SFOE).

Compared to standard anode supports, that usually crack after the first reoxidation, redox cycling capability of alternative anode supports developed here (small cells) was dramatically enhanced. Cells were redox cycled repeatedly (4x) without failure, losing only 0.5% in open circuit voltage (OCV) per cycle. Using an appropriate cathode, no loss in electrochemical performance (area specific resistance, asr) was detected after 4 complete redox cycles. However, the penalty paid for increased redox-stability lay in significantly lowered power density of these cells (0.5 W/cm2, 800°C) compared to small cells using the standard anode support (>1.0 W/cm2).

The conductivity of the redox-stable anodes was lowered (100 S/cm) compared to standard supports (1000 S/cm), as well as their mechanical strength. Different elements were added to the anode in order to increase conductivity and strength, while also lowering its thermal expansion coefficient.

 Sponsored by the Swiss Federal Office of Energy (SFOE).

2. Realization of a reactor for the partial oxidation of natural gas to syngas based on oxygen separation ceramic membranes - proof of concept (2001-2002).

The goal of this project was to achieve a partial oxidation (POX) reactor based on the oxygen separation membrane (OSM) technology, for the conversion of natural gas (NG) into syngas (CO + H2). The production of syngas is an interesting way to valorise NG, since this hydrogen-rich gas mixture can be directly converted into electricity by SOFC systems. Furthermore, syngas is a major intermediate for the production of both hydrogen and gas-derived liquids, which are of growing interest for both economic and environmental reasons.

There were five main milestones:

The first milestone was to demonstrate the stability of OSM in real operating conditions, i.e. when placed in a strong partial oxygen gradient and while delivering oxygen; The second milestone consisted in fabricating tubes out of the OSM material selected in the previous step; The third milestone was to demonstrate the POX of methane to syngas using a catalyst deposited on an OSM pellet (planar geometry). This implies, as a preliminary step, the selection of a catalyst for the POX reaction that is stable towards soot formation and compatible with the OSM material. The fourth milestone was to demonstrate the operation of a tubular POX-reactor (i.e. a tubular OSM combined with the POX-catalyst) over 1000 hours. Finally, the fifth milestone tackled the concept of an auto-thermal POX-reactor. All of the milestones were achieved. In particular, a tubular POX reactor was built and tested over 1000 hours showing good and stable catalytic characteristics: the methane conversion was >95%, CO selectivity was >90% at 900°C.

This project was supported by the research fund of the Swiss Gas Union (FOGA).
 
3. Pilot manufacturing of Solid Oxide Fuel Cells (SOFC) stacks (2003-2004).

The objective of this project is the set up of a pilot industrial manufacturing line for a new design of solid oxide fuel cell stacks. Issues such as automation, reproducibility, quality control and logistic supply will be addressed in order to set up a manufacturing of SOFC stacks in accordance with external (commercial) and internal (R&D) demand.

This project was supported by the research fund of the Swiss Gas Union (FOGA).