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The mixing quality of a single mixing unit and mixer arrays having various designs was characterized. A known test reaction for mixing quality had to be optimized, since a much higher sensitivity as for the characterization of macroscopic mixers was needed. This adapted test reaction allowed not only the characterization of the mixing quality but also analysis of the homogeneity of the flow distribution between parallely aligned mixing units. A comparison of the mixing quality to those of macroscopic reference systems (like mixing in stirred and unstirred vessels as well as to laminar and turbulent mixing-tees) is presented. The mixing quality−volume flow dependence revealed a complex behavior, the hydrodynamic origin of which has been analyzed.

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Ethylene oxide synthesis has been chosen as a benchmark case to evaluate the performance of a microreaction system in comparison to an existing industrial process. This reaction was selected because microreaction technology provides equipment with very good mass-and heat-transfer conditions, which avoids hot spots inside the reactor channels that are known problems for the partial oxidation of ethylene. Furthermore, because the microstructured reactors are inherently safe with respect to explosions, gas compositions within the explosion limits are attainable and can be handled safely. For example, 15% ethylene in pure oxygen, which is in the middle of the explosive regime and far away from typical compositions for industrial processes, could be used. Space time yields of 0.14-0.78 tons h -1 m -3 calculated on the basis of the channel volume, in comparison to the values of 0.13-0.26 tons h -1 m -3 for an industrial reactor calculated on the basis of the reactor volume, have been achieved by using the microreactor.

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