Progress in fuel processing for PEMFC systems for transport applications
Wellman CJB Limited has been developing fuel processors for PEMFC systems for transport applications using a range of feedstocks. Feedstocks that can be processed to produce a hydrogen-rich gas stream suitable for use with a PEMFC include methanol, gasoline, diesel, LPG, dimethylether, marine diesel and aviation fuel. The basic fuel processor is a steam reformer combined with a selective carbon monoxide oxidation stage. Depending on the nature of the liquid feedstock, other process steps will be required such as vaporizer, desulfurizer, pre-reformer and high and low temperature shift reactors. Work on methanol reforming has been specifically targeted at a PEMFC driven passenger car as part of a multinational European Community JOULE programme called MERCATOX. The objective is to develop and test a compact and fast response methanol reformer and gas clean-up unit to meet a car manufacturer's specification. The method of construction is to coat a methanol reforming catalyst onto one side of a metal corrugated plate. On the other side is a coated combustion catalyst which burns fuel cell off-gas to provide the endothermic heat for the methanol reforming reaction. A number of these plates are assembled in a compact unit ensuring good heat transfer. The gas clean-up unit is similarly constructed with a selective oxidation catalyst on one side and a thermal fluid on the other. Initial tests have indicated a superior performance to conventional packed bed reformers in terms of response and start-up time. Steam reforming of gasoline, diesel, LPG, dimethylether, marine diesel and aviation fuel has been demonstrated on a bench scale (0.5kW). The process steps commence with vaporization (except for LPG), desulfurization (except for dimethylether), prereforming, reforming, low and high temperature shift and selective oxidation. A simple technology demonstrator has shown that a hydrogen-rich mixture (75% hydrogen, 25% carbon dioxide) with less than 2ppm carbon monoxide can be produced consistently. Fifty hours operation was demonstrated with each feedstock. The only potential problem was when using marine diesel (0.5% sulfur) as the feedstock, the desulfurizer performance fluctuated. As an option to a carbon monoxide selective oxidation system, the separation of hydrogen using a thin film silver/palladium membrane coated onto a ceramic substrate is being investigated as part of a European Community JOULE programme. The device is targeted for use with a methanol reformer in a PEMFC vehicle and hence the developed device has to meet a car manufacturer's specification in terms of performance and cost. Coating techniques being investigated include magnetron sputtering, chemical vapor deposition, electroless plating, laser deposition and pore plugging.
- Research Organization:
- Wellman CJB Ltd., Portsmouth Hampshire (GB)
- OSTI ID:
- 20002742
- Country of Publication:
- United States
- Language:
- English
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