New Polymer Membrane Enables Low-Energy Crude Oil Fractionation

Crude oil fractionation by membrane. Image Credit: KAIST

​Researchers from KAIST and Georgia Tech have developed an innovative polymer membrane that separates crude oil at room temperature, offering a highly energy-efficient alternative to conventional distillation. Unlike traditional refining, which requires heating crude oil to temperatures above 350°C, the new membrane enables precise molecular separation without boiling, addressing one of the refining industry’s most energy-intensive and carbon-intensive processes.
Globally, crude oil distillation consumes approximately 1,100 TWh of energy annually, equivalent to the continuous output of about 130 large 1 GW nuclear power plants. This makes refining one of the largest industrial contributors to greenhouse gas emissions, while also exposing fuel and petrochemical prices to energy market volatility. The need for alternative separation technologies has therefore become increasingly urgent.
The new system uses a porous polyacrylonitrile (PAN) membrane without requiring an additional selective coating layer. As crude oil flows through the membrane, heavier hydrocarbon molecules spontaneously deposit on the pore walls, gradually narrowing the channels and forming self-assembled nanochannels of approximately 2 nanometres in diameter. These nanoscale pathways selectively allow lighter fractions such as naphtha, gasoline, and kerosene to pass through, while retaining heavier components.
This mechanism effectively converts what is normally considered membrane fouling into a functional advantage, using natural deposition processes to create highly selective separation pathways. The result is a dynamic, self-adjusting filtration structure formed directly by the crude oil–membrane interaction.
Performance tests demonstrated that the membrane achieves separation rates up to 23 times higher than state-of-the-art crude oil membranes reported previously, while maintaining stable operation over 28 consecutive days without performance degradation. The system also showed strong selectivity across complex real crude oil mixtures, confirming its industrial relevance.
Importantly, the technology is designed for practical deployment. It can be integrated into existing refinery infrastructure as modular filtration units, allowing retrofitting into current pipeline systems without requiring large-scale equipment replacement or redesign of refinery operations.
Process simulations further indicate that using the membrane as a pretreatment step before conventional distillation could reduce energy consumption by 31.6%, carbon dioxide emissions by 37.6%, cooling water usage by 20.7%, and operating costs by 36%. At a national scale, widespread adoption in the refining and petrochemical sector could reduce greenhouse gas emissions by approximately 10 million tons annually, equivalent to the emissions of around 4 million passenger vehicles.
Beyond crude oil refining, the membrane platform shows strong potential for broader industrial applications. These include the separation and upgrading of waste plastic pyrolysis oils, recovery of high value solvents in battery manufacturing, pharmaceutical purification processes, and biofuel production. Its versatility positions it as a promising platform technology for next generation sustainable chemical separations.
Overall, this work demonstrates a new paradigm in membrane science, where complex fluid material interactions are harnessed to create functional separation structures in situ, offering a scalable pathway toward lower energy and  emission industrial processing.
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