Dominik Brühwiler

The suitability of silanes H 2 N(C 3 H 6 )Si(OC 2 H 5 ) 3‐x (CH 3 ) x (x=0, 1, 2) for the sealing of zeolite pores has been investigated. The sealing efficiency was evaluated by observing the exit kinetics of the fluorescent dye resorufin from the one‐dimensional main channels of zeolite L (ZL). The best results in terms of sealing quality were obtained with x=0, indicating the importance of ensuring maximum probability for siloxane bond formation and cross‐linking during the sealing process. The amino group thereby plays a crucial role in the positioning of the silane prior to covalent bond formation. Samples sealed with 3‐aminopropyltriethoxysilane (APTES) showed excellent stability against leaching in aqueous medium even under moderately alkaline conditions. Further evidence for the ability of APTES to efficiently seal the channels of ZL was obtained by nitrogen sorption measurements.