From Crude Oil To Jet Fuel: Energy-Efficient Membrane Technology Could Transform Oil Refinery

Researchers develop polymer nanofilms to separate crude oil into jet-fuel-range hydrocarbons, offering a scalable, low energy alternative to thermal-driven distillation.

Summary

• Researchers create ultrathin nanofilms that allow for rapid and selective separation of crude oil into kerosene-range hydrocarbons, the dominant components of jet fuel
• Membrane technology could reduce energy consumption and carbon emissions by up to 90% compared to conventional distillation used for crude oil fractionation

Crude oil refining is the starting point for a variety of hydrocarbon products that we rely on in our everyday lives, including gasoline, diesel, jet fuel, lubricants, and plastics. Currently, the conventional method of crude oil separation relies on thermal-driven distillation, which contributes to nearly one percent of global energy consumption.

In Singapore, more than 1.5 million barrels of crude oil are processed daily. Refinery accounts for approximately 34 percent of industrial energy use and 29 percent of industrial carbon dioxide emissions, highlighting the demand for more sustainable separation technologies.

A lower cost and less energy-intensive alternative
This is where membrane technology enters the picture. A group of scientists from Queen Mary University of London and Exactmer Limited have developed ultrathin polymer nanofilms that act as ‘sieves’ to filter crude oil and produce kerosene-range hydrocarbons.

The lead corresponding author of the study is currently Nanyang Assistant Professor Jiang Zhiwei from the School of Chemistry, Chemical Engineering, and Biotechnology (CCEB) at Nanyang Technological University, Singapore (NTU Singapore). A part of his postdoctoral research in London was recently published in Science, entitled ‘Ultrathin polymer membranes with locked intrinsic microporosity for hydrocarbon fractionation’.

By using polymer membranes about 5000 times thinner than a sheet of paper, these nanofilms can separate crude oil into valuable fractions by size and class. The usage of ultrathin polymer membranes could reduce energy consumption and carbon emissions by up to 90 percent compared to conventional distillation.

Understanding polymer membranes
The work was inspired by polymers of intrinsic microporosity (PIMs) used for gas separations. PIMs contain rigid units that create thousands of tiny pores, enabling molecules to be separated by size. However, when exposed to crude oil, the polymer chains can move apart and swell, causing the pores to enlarge and reducing the membrane’s ability to selectively filter hydrocarbons.

“It is a bit like instant noodles. When they are dry, they are compact and rigid. But once you add water, they swell and the spaces between them become larger. A similar phenomenon happens in polymer membranes when they are exposed to crude oil.” - Prof. Jiang

To overcome this challenge, Prof. Jiang and his colleagues developed Polymers of Locked Intrinsic Microporosity (PLIMs) by simultaneously crosslinking and packing the polymer chains during nanofilm formation. This process effectively pulls neighbouring polymer chains together and locks the pore structure in place, greatly reducing swelling. As a result, PLIM nanofilms maintain their sub-nanometre pores for enabling rapid transport of smaller hydrocarbons and retention of larger ones.

Potential industrial applications
The nanofilms exhibited a ten-fold higher permeance for synthetic crude oil compared with commercial and literature-reported membranes, while also achieving higher selectivity.

Beyond their superior performance, the PLIM membranes are highly scalable. The team successfully scaled up the technology using a roll-to-roll manufacturing process to produce continuous membrane sheets measuring 5 metres by 0.3 metres.

These membranes were assembled into pilot-scale modules and maintained stable performance while in continuous operation for over one month, demonstrating their potential for industrial deployment.

When applied to Arabian Extra Light crude oil, the PLIM membranes removed more than 99 percent of hydrocarbons containing over fifteen carbon atoms and 93 percent of sulphur-containing compounds. The permeate transformed from a dark crude oil feed into a colourless liquid with a composition closely resembling kerosene, the principal hydrocarbon fraction in jet fuel.

“What excites us is that we are not simply ‘sorting’ crude oil into lighter and heavier fractions,” Prof Jiang said. “We can make very sharp separations at specific carbon numbers, allowing us to selectively remove hydrocarbons above a desired threshold.”

Moving forward
At NTU Singapore, Prof. Jiang and his team are now developing a new generation of membrane materials known as Ultrathin Nanofilm of Interconnected Cavities (UNIC). These membranes are designed to complement existing refinery infrastructure and could also be applied to high-value pharmaceutical manufacturing, catalyst recovery, and sustainable aviation fuel production.

While the current PLIM membranes can effectively separate hydrocarbons with more than 15 carbons, Prof. Jiang sees them as only the first step towards a broader membrane platform for hydrocarbon refining. He explained that a complete membrane-based refinery would require a family of membranes with different pore sizes working together, with each membrane targeting a specific hydrocarbon fraction.

“That is why we are developing UNIC,” said Prof. Jiang. “By tailoring membrane pore sizes with sub-nanometre precision, we envision multiple membrane stages to progressively cut off crude oil into valuable products, much like a distillation train, but more energy efficient.”

While oil refinery has been developed and optimized for more than a century, advances in membrane science are opening new possibilities for how hydrocarbon separations may be performed in the future.

“Conventional distillation separates crude oil using different temperatures; our vision is to separate crude oil using different pore sizes.” - Prof. Jiang