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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Abstract. Since 1937 ethylene oxide has been produced by direct oxidation of ethylene over a supported silver catalyst and it has become a very important industrial product. Consequently, the synthesis of ethylene oxide has been the subject of a large number of scientific and industrial studies. These examinations of the ethylene oxidation have suggested that this process can be used for the comparison of potential microreactor systems to current industrial processes. Therefore, this reaction was chosen as a benchmark to evaluate the potential of a microstructured reactor in the synthesis of ethylene oxide. Here, a microreactor, designed and constructed by IMM, was used for the investigations. Silver foils (126 channels: length 9 mm, height 50 f-lm, width 500 f-lm) served as the catalytically active component. Most of the experiments worked at pressures between 5 and 15 bar in a temperature range of 500-570 K. In order to optimize the selectivity while still having a satisfying yield, the reactant gas composition was varied over a wide range. In this study it was found that the selectivities and conversions reached were comparable to those achieved in industrial processes and the selectivity was not strongly dependent on the oxygen concentration. Additionally, the possibility to run the reactor with gas compositions within the explosion limits for ethylene was demonstrated.