A Georgia Tech-led team of scientists have developed a new membrane technology to reduce CO2 emissions and energy use while refining crude oil.
According to the Georgia Tech, Imperial College London, and ExxonMobil scientists, fractionation of crude oil mixtures using heat-based distillation is a large-scale, energy-intensive process that accounts for nearly 1% of the world’s energy use.
Using low-energy membranes for certain steps in the distillation process could one day lead to the implementation of a hybrid refining system that’s not only efficient but also eco-friendly too, opines the team.
Membrane technology is widely used in seawater desalination, but the complexity of petroleum refining has until now limited the use of membranes.
To overcome this, the scientists developed a novel spirocyclic polymer that was applied to a robust substrate to create membranes capable of separating complex hydrocarbon mixtures through the application of pressure rather than heat.
Membranes separate molecules from mixtures according to differences such as size and shape. When molecules are very close in size, that separation becomes more challenging.
To remedy this, the team used a well-known process for making bonds between nitrogen and carbon atoms to create their polymers.
These polymers have a kinked structure for creating disordered materials with built-in void spaces.
The scientists then balanced a variety of factors to create the right combination of solubility and and structural rigidity.
They also found that the materials needed a small amount of structural flexibility to improve size discrimination, as well as the ability to be slightly ‘sticky’ toward certain types of molecules that are found abundantly in crude oil.
After designing the novel polymers and achieving some success with a synthetic gasoline, jet fuel, and diesel fuel mixture, the team decided to try to separate a crude oil sample.
To their delight, the new membrane proved to be quite effective at recovering gasoline and jet fuel from the complex mixture.
The researchers worked collaboratively, with polymers designed and tested at Georgia Tech, then converted to 200-nanometer-thick films, and incorporated into membrane modules at Imperial using a roll-to-roll process.
Samples were then tested at all three organizations, providing multi-lab confirmation of the membrane’s capabilities.
Image and content: Christopher Moore/Georgia Tech