Nanoporous zeolite single crystals: ZSM-5 nanoboxes with uniform intracrystalline hollow structures

ZSM-5 nanoboxes with very regular pore geometry and wall thickness have been obtained by pseudomorphic transformation of silicalite-1 crystals. The transformation involves the preferential dissolution of crystal cores, followed by local re-crystallization of species in the presence of aluminum and templating molecules. By contrast to conventional dissolution methods, most of the crystals are perfectly closed and contain a unique central hole, which shape follows that of the original crystal. Moreover, the method is particularly interesting because hollow ZSM-5 with such size and regularity cannot be obtained by direct synthesis. The coexistence of thin walls, significant mesoporosity and high aluminum contents in the crystals is a real opportunity to improve the catalytic activity of the zeolite in reactions limited by diffusion.