Development of Microreactions for Applications to Thermochemical Reactors and Miniaturized Fuel Cells

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Microreactor systems with functions of catalytic reaction of steam reforming and membranes for Co removal were developed for use in fuel cell systems. The following results were newly obtained in this study.(1) Techniques for fabricating microchannels and modifying channel walls were developed, using various substrates which were resistant to elevated temperature and corrosive chemicals.(2) Techniques for coating the microchannels with metal catalysts were developed.(3) A system which enabled to select proper catalysts efficiently was developed by combining the microchannels catalytic reactors and a quadropole mass spectrometer.(4) A microchannel catalytic reactor was systemized with a miniaturized heater and thin film temperature sensors. Thus a thermally self-supporting microreactor was prepared.(5) A liquid evaporator was developed by combining a pump and a microheater on a silicon substrate. The pump was prepared using three thermally resistant piezoelements and showed a capacity enough for feeding methanol to miniaturized fuel cells.(6) Steam reforming of methanol produces CO, which is a severe catalyst poison, at a high concentration. In order to decrease CO concentration to a level of 10 ppm, temperature resistant inorganic membranes (zeolite and palladium) were developed. The zeolite membranes functioned as a high performance CO oxidation reactor, and the palladium membrane showed a very high H_2/CO selectivity.