Researchers have developed a microfluidic technique for fabricating a new class of metal-organic framework (MOF) membranes inside hollow polymer fibers that are just a few hundred microns in diameter. The process, believed to be the first to grow MOF membranes inside hollow fibers, could change the way large-scale energy-intensive chemical separations are done.
By replacing energy-intensive distillation or cryogenic techniques, these molecular-sieving membranes could cut the cost of gaseous and liquid separations, reduce energy consumption, and lead to industrial processes that generate less carbon dioxide. The researchers have demonstrated that membranes produced with the new technique can separate hydrogen from hydrocarbon mixtures, and propylene from propane.
“This work opens up new ways of fabricating molecular-sieving separation membranes using microscopic hollow fibers as a platform,” said Sankar Nair, a professor in Georgia Tech’s School of Chemical & Biomolecular Engineering. “Many of the separations that currently are done with energy-intensive techniques could one day be performed with membranes fabricated by a scaled-up version of our methodology.”
Energy-intensive separation processes are widely used in the industrial production of petro-based and bio-based fuels and chemicals, as well as a variety of other technological materials. The most common separation technique is distillation, which applies heat to chemical mixtures to drive off specific molecules according to their boiling points.
In contrast, molecular-sieving membranes use semipermeable materials to separate molecules from mixtures that are produced by chemical reactions or found in raw material feed stocks. The process may be driven by a pressure gradient, and relies on the membranes to preferentially pass certain molecules through their pore structures. Crystalline materials known as zeolites have been fabricated into membranes, but high membrane fabrication costs and a limited selection of materials have prevented their widespread use.
Development of the MOF fabrication methodology was described in the journal Science. This work was supported by the Phillips 66 Company.