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A microreactor technology, in which a microchannel is used as a catalytic reaction field in order to supply hydrogen to a small polymer electrolyte fuel cell (PEFC) for portable electronic devices, was described. The reduction of heat loss in the microreactor is the primary requirement for improving system efficiency, since heat release in microreactors is higher than in conventional reactors due to the increased specific surface area. Therefore, the methanol steam reforming, operated below 300 , is an appropriate process for the hydrogen production using the microreactor. First, the high-performance Cu/ZnO/Al2O3 catalyst for methanol reforming at low temperature was developed under the optimized preparation condition. The miniaturized methanol reformer was then developed to utilize this Cu/ZnO/Al2O3 catalyst. The length of the microchannel was determined based on one-dimensional mass and heat balance analyses. The microreactor was fabricated from silicon and glass substrates using a number of microfabrication techniques. Methanol reforming using this reactor has been demonstrated to reach the levels necessary to power a 1 W-class small PEFC system. The multilayered integrating the miniature methanol reformer with a CO remover, a catalytic combustor as a heat source for methanol reforming, vaporizers, and several necessary functional elements for hydrogen production has also been successfully fabricated. Finally, the microreactor system has been demonstrated to produce hydrogen at a rate sufficient to generate electrical power of 2.5 W.

A small proton exchange membrane fuel cell (PEMFC) system with a multi-layered microreactor for methanol steam-reforming was prototyped as a power source for mobile electric applications. The multi-layered microreactor was designed using a computational simulation. It consists of four units: a methanol reformer with a catalytic combustor, a CO remover, and two vaporizers. The catalytic combustor for supplying reaction heat of reaction to other units was located on the top of microreactor. The microreactor was operated in a vacuum package to improve the system efficiency, and the suitable temperature distribution for the methanol steam-reforming was reached by supplying heat from the catalytic combustor. The small PEMFC has two humidifiers, which were composed of hollow fibers and a water holder. This system generated an output of approximately 2.5 W at 200 mA/cm2.