A membrane that works better as it clogs could cut the energy used to refine crude oil by 31.6%

Fouling is the usual enemy of a membrane: heavy material builds up in the pores, flow drops and the filter is retired. Researchers at KAIST in South Korea and Georgia Tech reported in Nature that a plain polyacrylonitrile membrane does the opposite with crude oil, growing more selective as heavy hydrocarbons settle inside it. Their process simulations put the energy savings at 31.6% when the membrane is used ahead of conventional distillation.

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The stakes come from the scale of the incumbent process. Crude oil distillation consumes roughly 1,100 terawatt-hours of energy a year worldwide, about the output of 130 one-gigawatt nuclear plants, and conventional towers heat the oil above 350 degrees Celsius. The paper went online on June 24, and a summary reached ScienceDaily on Nov. 3, crediting Koh as lead investigator, Lively as collaborator and Jae W. Lee of KAIST as co-corresponding author.

Pores that narrow below 2 nanometers

According to ScienceDaily’s summary, the membrane is bare polyacrylonitrile, an inexpensive polymer with no specialized coating, and the work appears in Nature under the paper name Crude oil fractionation by means of mesoporous polyacrylonitrile membranes. As crude flows across the material, heavier hydrocarbons accumulate on the pore walls and narrow the openings to under 2 nanometers. Those self-formed channels let lighter fractions such as naphtha, gasoline and kerosene pass quickly while slowing heavier molecules, so the lighter products that towers boil off come through the membrane first. KAIST’s Dong-Yeun Koh, who led the study, called it a new scientific principle (he is an associate professor at KAIST and a former postdoc in Lively’s lab), one in which a membrane interacts with a complex mixture and spontaneously forms its own separation channels.

Ryan Lively of Georgia Tech, the corresponding author whose group published earlier crude oil membrane work in Science in 2020, said in Georgia Tech’s release that the new study grew directly out of challenges identified in those original findings. He added that membranes offer a path to separations with dramatically lower energy requirements and emissions than heat-driven distillation.

A 23-fold flow gain and four weeks of operation

Two performance numbers carry the claim. The membrane’s crude oil permeation rate is about 23 times that of earlier leading crude oil separation membranes, and it held stable performance for 28 consecutive days of continuous operation. HD Hyundai Oilbank supplied real crude oil for the tests, so the trials used an industrial feedstock rather than a laboratory stand-in, according to the EurekAlert release from the two universities.

Lively’s own assessment was that industry should seriously consider adopting the technology.

The membrane’s base material explains part of the interest. Polyacrylonitrile is usually used only as a support layer beneath the active film of other membranes, according to the KAIST page, and here it does the separating itself. Under tangential flow, with the crude sweeping across the surface rather than pushing straight through, the membranes enrich the lighter fractions, specifically naphtha and kerosene. The selectivity comes from heavy hydrocarbons depositing inside the pores, a self-limiting process that stops once the openings narrow to the right size.

Conventional atmospheric and vacuum distillation, the same page notes, consume more than 1,100 terawatt-hours a year in petroleum refining and emit more than 160 million metric tonnes of carbon dioxide equivalent annually. That baseline is what the 37.6% emissions figure is measured against, and it frames why a pretreatment step, rather than a full replacement of distillation, is the use case modeled.

Simulated savings: 31.6% energy, 37.6% carbon dioxide, 36% cost

The savings figures come from simulations, not operating refineries. In the KAIST-Georgia Tech release, using the membrane as a pretreatment step before distillation would cut energy use by 31.6%, carbon dioxide emissions by 37.6%, cooling water by 20.7% and operating costs by 36%. Georgia Tech’s own summary rounds these to about 30% for energy and about 35% for emissions, so readers may meet slightly different figures for the same study. The release adds that adoption across Korea’s refining and petrochemical sector would trim greenhouse gas emissions by about 10 million tonnes a year.

A KAIST chemical engineering page lists eleven authors, with Jae W. Lee, Lively and Koh as corresponding authors. Georgia Tech notes the same effect appeared in a second membrane material, a hint that the principle may reach beyond polyacrylonitrile. The journal reference is Nature, volume 654, issue 8120, page 955.

No refinery has run the membrane. Jihoon Choi and Hyeokjun Seo of KAIST are the co-first authors, and Georgia Tech says the flow rate is more than 23 times what its 2020 Science paper reported for whole crude oils. The 31.6% applies to one process configuration, the membrane as pretreatment before distillation, and ScienceDaily states plainly that these are modeled projections. Georgia Tech’s release names no next steps and no funding, and the longest reported test is 28 days, so whether the pore-narrowing effect stays stable over much longer periods remains to be shown.

This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.

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