Posted on 06/05/2025 5:57:05 AM PDT by Red Badger
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.
Crude Oil Membrane Filter
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
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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
The research was funded, in part, by ExxonMobil through the MIT Energy Initiative.
Cool. Like desalination on steroids.
I long for the day that the influence of DJT policies eliminate such thinking and I can read an article absent such psychotic language.
Hold thy breath? Nay.
Besides, absent action by the worthless Congress, it will snap back like a coiled spring when he's gone.
Coffee filter applied to oil?
Interesting. I’d think it would make oil refineries a lot safer, too.
Interesting. If they can truly make this commercially viable in is a game-changet in the refining business.
And smaller...........................
Immensely so. The “cracking” unit in a refinery is subject to explosions on occasion.
And cheaper to build, probably. Whether cheaper to operate would likely depend on the cost and service life of the membranes.
“Whether cheaper to operate would likely depend on the cost and service life of the membranes.”....and Union contracts.................
How much heat and pressure are required to push the molecules through a membrane? What about impurities clogging the membrane? Because something works on a small scale does not make it feasible for commercial production.
The paper makes no mention of what types of crude oil this membrane cold be applied to. I’m not a petroleum engineer, but I’d think you’d have a hard time pushing medium, heavy, and extra-heavy crude oils through a membrane. It could be applicable to light crude oils, but these are only 15-20% of global reserves.
Early in my career, I burned “Bunker C” fuel which is the “bottoms” from the distillation process. After distillation, refineries use vacuum distillation to reduce the boiling point of “Residual Oil” and what comes out the bottom of that process is Bunker C. It’s nasty stuff, lots of sulfur and metals, and must be heated 24x7. Stop heating it and it freezes into a block of solid tar.
Heavy Oil (API < 22.3°): 25–30% (~430–520 billion barrels)
Driven by Venezuela (303 billion barrels, mostly heavy/extra-heavy) and Canada (171 billion barrels, oil sands). Smaller contributions from Mexico, Colombia, and Middle Eastern heavy fields (e.g., Iraq, Kuwait).
Medium Oil (API 22.3°–31.1°): 50–60% (~865–1,040 billion barrels)
Dominant in Saudi Arabia, Iran, Iraq, Russia, UAE, and Kuwait, where conventional fields produce medium crudes. This is the largest category due to the prevalence of these fields.
Light Oil (API > 31.1°): 15–20% (~260–345 billion barrels)
Significant in U.S. shale (tight oil), Saudi Arabia (Arabian Light/Extra Light), Libya, and Nigeria. Light oil’s share is growing with shale but remains smaller than medium.
Usefulness would depend on how long the separation process takes. E.g., by how much does this change the amount of time it takes to produce a barrel?
Thank you for pointing this out. It is exactly what I was going to say.
There is a big difference in refining Light Sweet Crude and Heavy Sulfur Crude. To the point that many countries/companies just can not do it cost effectively. Which is why the refineries in the Gulf coast of the USA do so much of it. It is also why we IMPORT this oil from other countries. Then export distillants like diesel.
They used to say that the crude from Quaker State was so light and pure you could pump it right out of the ground and put it into your engine. Arnold Palmer wouldn’t put anything else in his tractor.
Not so much for the stuff coming from Venezuela and the oil sands of Alberta.
Three decades ago an oil refinery was proposed to be built near Mobile, Arizona. Unfortunately, the Greenies put the kibosh on it under the pretext of the danger of pollution from the refinery.
Would this technology allay those fears?
No. They fear the product, not the process....................
Yes, the worst of the worst are:
Orinoco oil, from Venezuela’s Orinoco Belt, is primarily extra-heavy crude oil or bitumen. It is not extracted as a solid but as a highly viscous liquid, often resembling tar. Its high viscosity and density (API gravity typically 8–10°)
Athabasca Oil Sands from Alberta are bitumen mixed with sand, clay, and water.
“potentially allowing it to be scaled up for widespread use”
Journalists are crap. Completely useless after the 24 hr. news cycle was adopted. They have to make S up and speculate to produce
The question I would ask is cost of conversion of heavy crude fractation.
Also, how long would the filters last before plant would have to be taken down to clean/replace filters.
In Texas we crack a lot of heavies from West Texas and other countries.
Very cool. I wondering how much the filtration process cost for filters, pump pressure, unusable waste etc. This process isn’t cost free.
I’d bet the a good chunk of the energy used in current distillation is generated using other wise low grade or nearly useless by products.
The savings is probably only a small fraction compared the headline. But the 100 mpg carburetor is out there somewhere too.
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