Method for mounting monoliths in a reactor for carrying out heterogeneously catalyzed gas-phase reactions

The invention relates to a method for mounting monoliths (2), which are each formed from a ceramic block having a plurality of parallel channels through which the reaction gas mixture of the heterogeneously catalyzed gas-phase reaction can flow into a reactor (1) for carrying out heterogeneously catalyzed gas-phase reactions, the monoliths (2) being stacked in the reactor interior next to and above one another. The method is characterized in that the monoliths are sealed from each other and with respect to the inner wall of the reactor (1) by means of mats (3), each comprising an expanding mat, which prior to mounting in the reactor (1) are enveloped completely by plastic film, vacuum conditions being created in the interior enclosed by the plastic film and containing the mat (3). Once the monoliths are mounted in the reactor (1), the vacuum conditions in the interior enclosed by the plastic film and containing the mat (3) are reversed.