Properties and uses of Zeolites
Zeolites are very stable solids that resist the kinds of environmental conditions that challenge many other materials. High temperatures don’t bother them because they have relatively high melting points (over 1000°C), and they don’t burn. They also resist high pressures, don’t disssolve in water or other inorganic solvents, and don’t oxidize in the air. They’re not believed to cause health problems through, for example, skin contact or inhalation, though in fibrous form, they may have carcinogenic (cancer-causing) effects. Since they’re unreactive and based on naturally occurring minerals, they’re not believed to have any harmful environmental impacts. Although zeolites might sound incredibly boring, their stable and unreactive nature isn’t what makes them useful. The most interesting thing about zeolites is their open, cage-like, “framework” structure and the way it can trap other molecules inside it. This is how water molecules and alkali or alkaline-Earth metal ions (positively charged atoms with too few electrons, sometimes called cations) become a part of zeolite crystals—although they don’t necessarily remain there permanently. Zeolites or zeolith can exchange other positively charged ions for the metal ions originally trapped inside them (technically this is known as cation exchange) and, as Cronstedt found over 250 years ago, they can gain or lose their water molecules very easily too (this is called reversible dehydration). Zeolites have regular openings in them of fixed size, which let small molecules pass straight through but trap larger ones; that’s why they’re sometimes referred to as molecular sieves. Unlike natural zeolites, which occur in random forms and mixed sizes, synthetic zeolites are manufactured in very precise and uniform sizes (typically from about 1μm to 1mm) to suit a particular application; in other words, they’re made a certain size to trap molecules of a certain (smaller) size inside them.
In petrochemical industry, their usage is wide spread, as they are used as catalysts which help in increasing the rate of the reactions being carried out. Cracking of hydrocarbons is the most important step of manufacturing any petro-chemical product and Zeolites help people in this regard. This cracking is done through ion exchange method as Hydrogen form of Zeolites is used for this purpose. After the breaking down of large gasoline molecules into smaller ones, catalyst is injected which in turn increases the rate of reaction and effects the manufacturing of product, producing it in a fast and efficient manner. You can visit www.zeocem.com in order to have further information about Zeolites.