Incorporation of zinc into silica mesoporous molecular sieves

The direct syntheses of Zn/Si mesoporous materials [S. Kowalak et al., First ISMMS, Baltimore (1998), Poster Session] allowed to introduce only a limited number of Zn, and the mesostructures became less ordered at higher Zn loading. Therefore, we have attempted to graft zinc into the well ordered and stable silica structures of MCM-41, SBA-3, HMS. The properties of the resulting samples depended on the silica parent structure and on the number of zinc introduced. The structure of MCM-41 was affected drastically even by small amounts of zinc, whereas HMS and particularly SBA-3 retained their structure despite a relatively high zinc loading (Zn/Si = 0.15). Such Zn loading was not reached for the structures obtained by means of the direct synthesis. The samples with grafted zinc showed ion-exchange properties and considerable catalytic activity for 2-propanol decomposition. This was in contrast to the directly prepared samples for the series SBA-3. (C) 2001 Elsevier Science B.V. All rights reserved.