Hierarchical porous structures by using zeolite nanocrystals as building blocks

Hierarchical porous structures have been fabricated using colloidal zeolite silicalite nanocrystals as building blocks. Continuous, uniform, optically transparent and self-standing silicalite membranes with well-defined shapes and controlled mesoporosity were obtained by self-assembly of zeolite nanocrystals followed by high-pressure compression and controlled secondary crystal growth via microwave treatment. The thickness of the compact self-standing membranes is tunable from 20 mum to several millimeters by simply using different surface weight densities. Controlled secondary growth via microwave treatment leads to a stronger self-standing membrane with controlled mesoporosity and has little effect on its thickness, crystallinity, micropore surface area and micropore volume. (C) 2001 Elsevier Science B.V. All rights reserved.