Sungkyunkwan University (SKKU, President: Ji-Beom Yoo) announced that Professor Tae Hoon Lee’s research team from the Department of Future Energy Engineering, in collaboration with researchers from the Massachusetts Institute of Technology (MIT), has developed a high-performance ultramicroporous membrane* capable of replacing conventional crude oil refining processes. The study was published in the May 23 issue of the international journal Science.

*Membrane: A membrane is a functional material that selectively allows or blocks the passage of specific molecules based on size, shape, or chemical properties. Membrane-based separations require neither heat energy nor phase changes, offering a promising alternative to conventional, energy-intensive separation methods such as distillation.

Currently, crude oil refining primarily relies on thermal distillation, which accounts for approximately 1% of global energy consumption and 6% of CO₂ emissions, making it highly energy-intensive. Although polymer membranes based on Polymers of Intrinsic Microporosity (PIMs)** have been explored as an alternative, their commercialization has been hindered by high costs, low selectivity, and susceptibility to swelling and plasticization when exposed to organic solvents.

**Polymers of Intrinsic Microporosity (PIMs): These novel materials feature rigid and contorted molecular structures that prevent dense packing of polymer chains, creating abundant free volume and sub-nanometer pores (<2 nm in size, BET surface area >100 m²/g).

To overcome these challenges, the research team replaced the conventional amide bonds found in commercial reverse osmosis membranes with imine bonds***, which offer superior resistance to swelling and lower polarity, thereby achieving both structural rigidity and ultramicroporosity. Furthermore, the incorporation of triptycene and spirobifluorene units enhanced the membrane’s resistance to swelling and plasticization, as well as its molecular selectivity. Notably, the membranes were fabricated using interfacial polymerization, an industrially validated process suitable for large-scale manufacturing.
***Imine bond: Formed via a condensation reaction between an amine (-NH₂) and an aldehyde (-CHO), the imine (C=N) bond is less polar and structurally more rigid than amide bonds.

Experimental results demonstrated that the new membranes can selectively separate fuel components based on molecular size, potentially reducing energy consumption by tens of percent compared to traditional distillation—a feature unattainable with existing commercial membranes.

Professor Tae Hoon Lee, the study’s first author, stated, “The ultramicroporous imine-based membranes we developed show groundbreaking potential to replace conventional thermal separation processes, potentially reducing the energy required for crude oil fractionation by up to several tens of percent. By leveraging an interfacial polymerization method compatible with industrial manufacturing, this technology not only promises scalability but also contributes to decarbonizing the petrochemical industry and could transform the future paradigm of eco-friendly fuel production and refining.”

This research was supported by the MIT Energy Initiative (MITEI) and the King Abdullah University of Science and Technology (KAUST) and was published in the May 23 issue of Science.

※ Paper Title: Microporous polyimine membranes for efficient separation of liquid hydrocarbon mixtures

※ Journal: Science

※ Authors: Corresponding Author: Zachary P. Smith; First Author: Tae Hoon Lee; Co-authors: Zain Ali, Taigyu Joo, Matthew P. Rivera, Ingo Pinnau

※ DOI: 10.1126/science.adv6886 (forthcoming)

▲Schematic Diagram of the Fabrication and Applications of Ultra-Microporous Separation Membranes via Acid-Catalyzed Interfacial Polymerization