MIT Creates Game-Changing Oil Filter That Could Revolutionize The Refining of U.S. Light Sweet Crude Oil

This technological advancement could be a boon for U.S. refineries which were designed to refine heavy sour crude oil.

Close-up of the potentially game-changing filter that could revolutionize refining.

Most U.S. refineries, constructed in the 1970s, were designed to process heavy, sour crude oil imported from South America and the Middle East. The U.S. shale revolution unlocked abundant reserves of light, sweet crude oil. While some older refineries have been retrofitted to handle light, sweet crudes more efficiently, the majority remain optimized for heavy, sour crude, creating a mismatch with domestic shale production.

MIT researchers recently developed a breakthrough membrane technology that separates crude oil into its components based on molecular size, potentially replacing the energy-intensive distillation process. This innovation could revolutionize U.S. refining by enabling more efficient and flexible processing of diverse crude types, especially shale-derived light, sweet crude oil.

I asked my long-time friend and Chemical Engineer, David Wadsworth, for his opinion on this new technology, and he said:

This article is an interesting development to existing membrane technology. The light streams from gasoline, jet, diesel and light vacuum gas oil, no problem. The key issue is how to handle the short residue and long residue and there is no way a membrane can handle either of these key refining streams. In fact the key to the economics of refining crack spreads is how long or short residue is converted to gasoline and diesel. So maybe this new technology would work best with very light Permian crudes and even Eagle Ford crude. That could be the key to utilizing this new tech for ultra light crudes and natural gas condensates.

I asked him a follow-up question: Since this new membrane technology is more suited to light, sweet Permian and Eagle Ford crude, would the membrane technology be a lower-cost way to economically run very light crude through existing refineries that we built to process heavy sour oil? His answer:

Yes, if you do not have to boil up the crude to make the initial separation of N,D, and J (naptha, distillate and jet fuel), it will save probably 40% of the Crude Distillation Unit energy. It is cheaper to pump up the crude oil to the membrane pressure then to boil the crude. This technology makes good sense to me for the light crudes and gas condensates when the residue is less.

My Take

This U.S. technology may be particularly useful in refining U.S. light sweet crude oil from the Permian and Eagle Ford shales. That would mean the U.S. would not only be the world’s largest producer of light sweet crude, but it could also be the lowest-cost refiner, giving the U.S. a worldwide advantage in both light-sweet crude oil and refined petroleum products.

It seems only fitting that U.S. shale resources would benefit from recent advancements in U.S. refining technology.

The SciTechDaily article follows.

MIT researchers have developed a new membrane that separates various types of fuel by molecular size, potentially eliminating the need for the energy-intensive process of crude oil distillation.

Turning crude oil into everyday fuels like gasoline, diesel, and heating oil demands a huge amount of energy. In fact, this process is responsible for about 6 percent of the world’s carbon dioxide emissions. Most of that energy is spent heating the oil to separate its components based on their boiling points.

Now, in an exciting breakthrough, engineers at MIT have created a new kind of membrane that could change the game. Instead of using heat, this innovative membrane separates crude oil by filtering its components based on their molecular size.

“This is a whole new way of envisioning a separation process. Instead of boiling mixtures to purify them, why not separate components based on shape and size? The key innovation is that the filters we developed can separate very small molecules at an atomistic length scale,” says Zachary P. Smith, an associate professor of chemical engineering at MIT and the senior author of the new study.

The new filtration membrane can efficiently separate heavy and light components from oil, and it is resistant to the swelling that tends to occur with other types of oil separation membranes. The membrane is a thin film that can be manufactured using a technique that is already widely used in industrial processes, potentially allowing it to be scaled up for widespread use.

Taehoon Lee, a former MIT postdoc who is now an assistant professor at Sungkyunkwan University in South Korea, is the lead author of the paper, which appears today in Science.

Oil fractionation

Conventional heat-driven processes for fractionating crude oil make up about 1 percent of global energy use, and it has been estimated that using membranes for crude oil separation could reduce the amount of energy needed by about 90 percent. For this to succeed, a separation membrane needs to allow hydrocarbons to pass through quickly, and to selectively filter compounds of different sizes.

Until now, most efforts to develop a filtration membrane for hydrocarbons have focused on polymers of intrinsic microporosity (PIMs), including one known as PIM-1. Although this porous material allows the fast transport of hydrocarbons, it tends to excessively absorb some of the organic compounds as they pass through the membrane, leading the film to swell, which impairs its size-sieving ability.

To come up with a better alternative, the MIT team decided to try modifying polymers that are used for reverse osmosis water desalination. Since their adoption in the 1970s, reverse osmosis membranes have reduced the energy consumption of desalination by about 90 percent — a remarkable industrial success story.

The most commonly used membrane for water desalination is a polyamide that is manufactured using a method known as interfacial polymerization. During this process, a thin polymer film forms at the interface between water and an organic solvent such as hexane. Water and hexane do not normally mix, but at the interface between them, a small amount of the compounds dissolved in them can react with each other.

MIT engineers developed a membrane, pictured, that filters the components of crude oil by their molecular size, an advance that could dramatically reduce the amount of energy needed for crude oil fractionation. Credit: MIT

In this case, a hydrophilic monomer called MPD, which is dissolved in water, reacts with a hydrophobic monomer called TMC, which is dissolved in hexane. The two monomers are joined together by a connection known as an amide bond, forming a polyamide thin film (named MPD-TMC) at the water-hexane interface.

While highly effective for water desalination, MPD-TMC doesn’t have the right pore sizes and swelling resistance that would allow it to separate hydrocarbons.

To adapt the material to separate the hydrocarbons found in crude oil, the researchers first modified the film by changing the bond that connects the monomers from an amide bond to an imine bond. This bond is more rigid and hydrophobic, which allows hydrocarbons to quickly move through the membrane without causing noticeable swelling of the film compared to the polyamide counterpart.

“The polyimine material has porosity that forms at the interface, and because of the cross-linking chemistry that we have added in, you now have something that doesn’t swell,” Smith says. “You make it in the oil phase, react it at the water interface, and with the crosslinks, it’s now immobilized. And so those pores, even when they’re exposed to hydrocarbons, no longer swell like other materials.”

The researchers also introduced a monomer called triptycene. This shape-persistent, molecularly selective molecule further helps the resultant polyimines to form pores that are the right size for hydrocarbons to fit through.

Efficient separation

When the researchers used the new membrane to filter a mixture of toluene and triisopropylbenzene (TIPB) as a benchmark for evaluating separation performance, it was able to achieve a concentration of toluene 20 times greater than its concentration in the original mixture. They also tested the membrane with an industrially relevant mixture consisting of naphtha, kerosene, and diesel, and found that it could efficiently separate the heavier and lighter compounds by their molecular size.

If adapted for industrial use, a series of these filters could be used to generate a higher concentration of the desired products at each step, the researchers say.

“You can imagine that with a membrane like this, you could have an initial stage that replaces a crude oil fractionation column. You could partition heavy and light molecules and then you could use different membranes in a cascade to purify complex mixtures to isolate the chemicals that you need,” Smith says.

Interfacial polymerization is already widely used to create membranes for water desalination, and the researchers believe it should be possible to adapt those processes to mass produce the films they designed in this study.

“The main advantage of interfacial polymerization is it’s already a well-established method to prepare membranes for water purification, so you can imagine just adopting these chemistries into existing scale of manufacturing lines,” Lee says.

Reference: “Microporous polyimine membranes for efficient separation of liquid hydrocarbon mixtures” by Tae Hoon Lee, Marcel Balcik, Zain Ali, Taigyu Joo, Matthew P. Rivera, Ingo Pinnau and Zachary P. Smith, 22 May 2025, Science.
DOI: 10.1126/science.adv6886

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