A Clogged Membrane Separates Crude Oil Without Heat, Study Finds

Researchers in South Korea and the United States report a way to separate crude oil at room temperature, using a cheap membrane that the oil itself turns into a precise filter. According to ScienceDaily, which published material from the Korea Advanced Institute of Science and Technology (KAIST), computer simulations suggest the approach could cut refining energy use by nearly 32%.

The work was published in Nature. It was led by Professor Dong-Yeun Koh at KAIST, together with Professor Ryan Lively's research group at Georgia Tech.

Why refining uses so much energy today

For more than a century, refineries have split crude oil mainly by distillation. The oil is heated to temperatures above 350 °C, part of it turns to vapor, and the vapors are cooled to collect different fractions.

According to the report, crude oil distillation worldwide uses about 1,100 terawatt-hours a year. That is comparable to the yearly electricity output of roughly 130 nuclear plants, each with a capacity of about one gigawatt, running continuously.

Membranes, which sort molecules without extreme heat, have long been considered an alternative. But the standard view was that they need an extremely thin, specialized coating to separate molecules precisely. Those coatings are expensive and can develop defects when made at large scale, which has held back industrial use.

How a clogged filter became the solution

The team skipped the coating. They used a bare membrane of porous polyacrylonitrile, known as PAN, an inexpensive and chemically stable polymer already common as a support layer in industrial filtration.

As crude oil flowed through the pores, heavier hydrocarbon molecules built up along the inner walls. That buildup narrowed the openings into channels less than 2 nanometers across. Lighter fractions, including naphtha, gasoline and kerosene, passed through quickly, while heavier material moved through much less easily.

The result is surprising because this kind of buildup, called fouling, is normally a problem that hurts filtration and forces cleaning or replacement. Here, the same effect made the membrane selective.

The uncoated PAN membrane let crude oil through at rates about 23 times higher than those reported for earlier leading membranes for crude oil separation. It also kept performing steadily for 28 consecutive days.

Lively said low productivity had been a key obstacle for these membranes. He said the PAN membranes raise it dramatically, to the point where “industry should seriously consider adopting the technology.”

What the simulations suggest

Refineries would not necessarily have to replace existing equipment, according to the report. The membrane could be installed as a modular unit that processes crude oil before it reaches conventional distillation, reducing the work left for the heating and separation stages.

Based on computer simulations, adding the membrane to the process could lower energy consumption by 31.6%. The summary also cites almost 38% lower carbon emissions and 36% lower operating costs. These figures are modeled projections, not results from a working refinery.

Why it matters beyond the refinery

Crude oil supplies more than gasoline and other transportation fuels. It is also a raw material for plastics, packaging, clothing and many everyday products. The report notes that refining costs feed into the prices of these materials, so a more efficient process could have wide economic and environmental effects.

For ordinary consumers, nothing changes immediately. The findings come from a research demonstration and modeling, and the sources do not describe any refinery plans to adopt the membrane. If it works at industrial scale, the potential gain is lower energy use and emissions in one of the world's most energy-intensive industries.

The researchers also describe the result as a shift in thinking. Fouling, long treated as a flaw in membrane design, may in some cases be put to work.

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Around Prague, based on reporting by ScienceDaily