Use of structured catalyst beds for preparing ethylene oxide

The present invention relates to a process for preparing ethylene oxide by reaction of ethylene with oxygen in the presence of at least one silver-comprising catalyst, wherein the reaction takes place in a reactor which has a catalyst packed bed having at least two zones (i) and (ii) and the silver content of the catalyst in zone (i) is lower than the silver content of the catalyst in zone (ii). The catalyst packed bed preferably has a further zone (a) with which the reaction mixture comes into contact before the zones (i) and (ii). According to the invention, the silver content of the catalyst in the zone (a) is higher than the silver content of the catalyst in zone (i).