Catalysts for the New Millennium
Zeolites are behind many high-tech marvels. These porous materials, made from metals and silicon, are today's most prodigious alchemists--or more properly, catalysts. They help transform crude oil into gasoline, plastics, detergents, and myriad other products. But zeolites have their limitations. Their holes are too small to accommodate large molecules, so they're out of the running for many new and complex compounds. Now that may change.
A research team at Arizona State University has created box-like structures that mimic zeolites in being very choosy about the size of molecule they let in. Moreover, these new boxes have much larger openings than any zeolite does. In fact, the openings are so large that the framework appears to be flimsy and weak (drawing). But appearances are certainly deceptive in this case. The structure is remarkably stable, says Arizona State chemist Michael O'Keeffe, thanks to a combination of organic and inorganic components--zinc oxide and terephthalic acid-- that rigidly reinforce each other.
Although the catalytic potential of this initial "metal-organic" material has yet to be explored fully, O'Keeffe is confident that the new approach will spawn a whole family of catalysts and new chemical tricks.By Otis Port