FAQs

The framework aluminum and silicon are bound to each other through shared oxygen atoms. The SiO4 units are neutral: Si+4 / 4 O- but the AlO4 results in a net negative charge: Al+3 / 4O- . The net negative charge is balanced by cations that are present during the synthesis. These cations are highly mobile and can be exchanged for other cationic species.

There are numerous naturally occurring and synthetic zeolites, each with a unique structure. The pore sizes commercially available range from approximately 3 Å to approximately 8 Å. Some of the commercial materials are: A, beta, mordenite, Y, ZSM-5.

Many zeolites are thermally stable to over 500 °C. Some are stable in an alkaline environment, and some are stable in acidic media. They are also stable to ionizing radiation and can be used to adsorb radioactive cations.

Zeolites can separate molecules based on size, shape, polarity, degree of unsaturation, among others.

Zeolites can be regenerated using relatively easy methods such as heating to remove adsorbed materials, ion exchanging with sodium to remove cations, or pressure swing to remove adsorbed gases.

Zeolite modification implies an irreversible change, unlike ion exchange or adsorption. There are a number of different ways that zeolites can be modified. The framework of the zeolite can be modified by synthesizing zeolites with metal cations other than aluminum and silicon in the framework. The framework of the zeolites can be modified by dealumination to increase the silica and increase the hydrophobic nature of the zeolite. There are many proprietary methods to modify zeolites that impart unique characteristics to them.

Zeolites are available as powders or as formed products such as extrudates. Zeolites, like other solids, are safe to handle and are easy to use in a variety of reactors.

During the 1930's, R. Barrer and J. Sameshima did extensive work in zeolite synthesis. In 1948, Richard Barrer first produced a synthetic zeolite that did not have a natural counterpart. At approximately the same time, Milton made the first materials that had no natural counterpart such as zeolite A.

New natural zeolites are still being discovered, and new synthetic zeolites are being invented in many laboratories around the world.

The combination of many properties, among them: the microporous character of the uniform pore dimensions, the ion exchange properties, the ability to develop internal acidity, the high thermal stability, the high internal surface area. These make zeolites unique among inorganic oxides.

Not all zeolites have been studied, but extensive studies have been done on zeolite A due to its use in consumer products. These studies have demonstrated that type A zeolite is essentially non-toxic via oral, dermal, ocular, and respiratory routes of exposure; type A zeolite was also found to be safe for the environment. Please consult the SDS for product(s) of interest.