Microreactors

Microreactors are miniature continuous flow reaction systems with micron sized channel and chamber widths. These new devices offer promising avenues toward more precise control over transport phenomena and reaction characteristics than is possible with traditional reaction technology. The differences between microreaction systems versus traditional reactors arise from the small dimensions of the channels and vessels, and the high surface-to-volume ratio in microreactors. Channels are typically in the range of 10-500 mm. If we compare a 30 m³ reaction vessel to a microreactor with channels 30 micrometers wide, the microreactor has a surface to volume ratio 100,000 times larger. Thus the heating and cooling surface, or catalytic contact area, is that much larger per volume. "In general, for a given gradient in physical properties as temperature, concentration, density, or pressure, the linear dimension determines these gradients and therefore, the driving force for heat transfer, mass transport, or diffusion flux."¹ These small dimensions give rise to an extremely small Reynolds number, therefore microreactors generally have fluid flow in the laminar regime.

Microreactors can be constructed in a variety of ways and from a variety of materials. Photolithographic techniques developed for the microelectronics industry can be used to construct devices of silicon or glass. Devices can also be formed of polymers, ceramics, and metals using other techniques, including micromachining, laser ablation, electroforming, and injection molding. ^{2, 3}

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