Imperial spinout scales up heat-free crude oil separation

MIT

IMPERIAL COLLEGE LONDON spinout Exactmer has developed a pilot-scale membrane that can separate crude oil fractions without heat, a breakthrough that could significantly reduce the energy required for oil refining.

In a paper published today in Science, the team, based across the UK, China, Saudi Arabia and Singapore, describe a 1 m-wide membrane manufactured using roll-to-roll processing. Exactmer CEO and lead researcher Andrew Livingston believes the study shows membrane fractionation technology is now “ready” for commercial application.

Conventional thermal distillation accounts for around 1% of global energy consumption. Membrane technology has long been considered a lower-energy alternative, with estimates suggesting energy savings of up to 90%. However, researchers have been unable to overcome a trade-off between separation speed and selectivity which has held back commercial progress.

The researchers say they have overcome that hurdle, reporting permeation rates around ten times higher than current state-of-the-art membranes while maintaining similarly high selectivity.

The advance stems from a new polymer structure whose microscopic pores remain stable when exposed to hydrocarbons. By introducing crosslinks during fabrication, the team prevented the swelling that typically reduces membrane performance.

“This preserves the tiny pores that make molecular separation possible, while still allowing hydrocarbons to flow through very quickly,” said Exactmer’s head of membrane development, Zhiwei Jiang.

Independent experts welcomed the work. Ryan Lively, professor of chemical and biomolecular engineering at the Georgia Institute of Technology, described it as a “remarkable achievement”. 

Lively added that, while crosslinking had been considered previously, the researchers had found “a sweet spot in terms of membrane performance”.

Real-world crude tests

In tests on Arabian extra light crude, the team’s membrane extracted almost 100% of hydrocarbons heavier than 15 carbon atoms and removed more than 90% of sulphur-containing compounds. The researchers say this could simplify refining by reducing the need for separate downstream desulphurisation. 

Although flow rates were lower when processing real crude than synthetic mixtures, the membrane maintained stable performance during 30 days of continuous operation. It was also integrated into standard spiral-wound modules already widely used by industry, demonstrating its potential for commercial deployment.

Lively said the successful scaleup from laboratory samples to a full-size membrane module was particularly encouraging.

“Being able to go from a small postage stamp test to a full-size membrane module in such a short time indicates that the prospects for membrane-based oil refining are bright,” he said. 

The team is now exploring green alternatives to chloroform, the solvent used to fabricate the membranes. Exactmer also plans to develop similar technology for pharmaceutical separations.