New Membrane for Industrial Chemical Separation Processes

A research team from the Georgia Institute of Technology and ExxonMobil has demonstrated a new carbon-based molecular sieve membrane that could dramatically reduce the energy required to separate a class of hydrocarbon molecules known as alkyl aromatics. The new material is based on polymer hollow fibers treated to retain their structure - and pore sizes - as they are converted to carbon through pyrolysis. The carbon membranes are then used in a new 'organic solvent reverse osmosis' (OSRO) process in which pressure is applied to effect the separation without requiring a phase change in the chemical mixture. The hollow carbon fibers, bundled together into modules, can separate molecules whose sizes differ by a fraction of a nanometer while providing processing rates superior to those of existing molecular sieve zeolites. Because it uses a commercial polymer precursor, the researchers believe the new membrane has potential for commercialization and integration into industrial chemical separation processes.

Transcript

00:00:00 Hydrocarbons today are separated primarily through what we call thermal separations, that involve usually distilling hydrocarbon mixtures. That particular separation requires an immense amount of energy. So the primary breakthrough, we believe, for this research is the proof of concept experiments behind a process that we call organic solvent reverse osmosis. Now the advance is, when you try to use normal membranes

00:00:27 in the presence of solvent molecules or high pressures, the membranes fail. So we've managed to create membranes that can withstand the high osmotic pressures to make the process work, up to 120, 130 atmospheres. And essentially, they are unmoved by the solvent molecules. They're essentially solvent proof. The membranes are based on fiber spinning technology. So here in the lab, we have a hollow fiber spinning

00:00:52 apparatus, and what that allows us to do is mass manufacture our membrane materials. We estimate that our membranes are at least 10 times more efficient than the existing technologies. Really, the exciting part is the energy efficiency. We had the potential to save 30 to 40 gigawatts of power, just by separating molecules more efficiently. And it's these mega scale problems, that can make major dents in the world's energy and power budget, that really drive it.

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