Zeolite has been known for decades as an absorbent and a catalyst in many industries. In the future, sheets of it just nanometers thick may be used to filter gasoline out of crude oil.
A team of researchers at the University of Minnesota led by materials science professor Michael Tsapatsis, found a way to make ultra-thin sheets of zeolite that can speed up filtration and save a lot of energy (and money) in the process.
Substances such as gasoline are usually distilled from the parent liquid. Gasoline, for example, is produced when crude oil is mixed with ordinary powdered zeolite, which helps to separate the gasoline and other products from the crude. Purifying gasoline -– or any other liquid –- requires additional filtration.
But that can eat up a lot of energy. Filtration can be a good 15 percent of the energy used in separating liquids. A lot of that energy is lost because the whole filtering process isn’t very efficient. Rising energy prices have made it tougher for industry to ignore the extra costs.
A molecular membrane, one that let molecules of only a certain size pass through, would go a long way towards boosting that efficiency and that’s where the invention of nanometer-scale films of zeolite comes in.
The researchers used sound waves in a centrifuge to develop “carpets” of zeolite that are have just the right thickness. The resulting product can be used to separate molecules like a sieve. Ordinarily zeolite is not that hard to make, but forms chunks rather than ultra-thin sheets.
If this can be commercialized, it could reduce costs in a lot of industrial processes, including purifying gasoline and separating precursors to polymers, or even purifying water.
Image: University of Minnesota