Zeolites get an organic makeover

The labyrinth of pores that characterize a family of inorganic crystals known as zeolites gives the crystals catalytic and adsorbent powers. The crystals, which occur in natural and synthetic forms, are used in refining petroleum, removing water from organic solvents, and a host of other laboratory and industrial processes (SN: 10/5/02, p. 213: Available to subscribers at Molecular Separations: New artificial sieve traps molecules).

Now, scientists in Japan have incorporated organic chemical groups into zeolites’ frameworks. Zeolites typically contain silicon and aluminum, with oxygen linking the elements together. Organic parts could enable zeolites to remove organic substances from water or catalyze different reactions than purely inorganic zeolites do, comments Christopher W. Jones of the Georgia Institute of Technology in Atlanta, who has tried to make organic zeolites.

In the April 18 Science, the Japanese researchers describe how they replaced a conventional starting material, called tetraethyl orthosilicate, with a substance equally hard to say: bis(triethoxysilyl) methane. This change resulted in the replacement of many oxygen atoms with methylene groups, each of which contains a carbon atom and two hydrogen atoms. These organic groups enabled the new zeolites to adsorb some organic molecules, but the zeolites didn’t catalyze any new reactions.

“Introduction of methylene groups is just a first step,” says coauthor Takashi Tatsumi of Yokohama National University. The scientists now plan to introduce catalytically active organic groups into their zeolites.

In the past, attempts at creating useful organic zeolites have hit snags, says Jones. For example, the organic groups in his zeolites stuck out of the framework and blocked its pores. The Japanese team has succeeded in incorporating the organic groups right into the zeolite framework.


If you have a comment on this article that you would like considered for publication in Science News, send it to editors@sciencenews.org. Please include your name and location.

More Stories from Science News on Materials Science