Science 333, 328–332 (2011)

Zeolites are microporous aluminosilicate crystals with pore diameters of approximately one nanometre and are used as catalysts in various industrial reactions. The reactions are, however, limited to those involving small molecules because larger molecules are unable to enter the narrow pores of the material. Ryong Ryoo and colleagues at KAIST and the University of California, Santa Barbara have now created a series of zeolite structures with both micropores and mesopores.

The structures have hexagonal arrays of mesopores formed from thin walls of microporous zeolite using bifunctional surfactants. Cationic species in the head group of the surfactant molecules direct the crystallization of the aluminosilicate frameworks, while aggregation of the surfactant forms the mesopore channels. The thickness of the walls and their zeolite framework can also be controlled by using different surfactants. Moreover, the diameter of the mesopores can be adjusted from around 3–20 nm by changing the surfactant or by adding hydrophobic swelling agents.

Ryoo and colleagues test the zeolite structures as catalysts in a number of different reactions involving bulky molecules, such as the synthesis of vitamin E, and find that they have higher activites than conventional zeolites.