Oak Ridge Turns Shopping-Bag Plastic Into Liquid Fuel

Oak Ridge National Laboratory has converted polyethylene into gasoline- and diesel-range oils at 170 degrees Celsius. The optimized run, reported in the Journal of the American Chemical Society, produced a 63 percent yield of liquid alkanes from C6 to C15 after five hours in a 2:1 melt of aluminum chloride and sodium chloride, with no added hydrogen and no noble-metal catalyst.

The paper went online April 7, 2025. Oak Ridge issued its news note April 8, 2026, and the work is circulating again in September 2026, just as commercial plants that already crack plastic into oil have been closing.

Oak Ridge Cuts the Heat to 170 Degrees

Polyethylene is the resin in shopping bags and white cutting boards, and most of it is still thrown away. Liqi Qiu, a postdoctoral researcher at the University of Tennessee, Knoxville, ran the experiments in the Oak Ridge lab of Sheng Dai, an Oak Ridge Corporate Fellow and co-corresponding author. Qiu called the result an efficient and selective polyethylene-to-gasoline conversion.

Zhenzhen Yang, an Oak Ridge staff scientist and the other co-corresponding author, said the group used commercially available inorganic salts as the reaction bath and as the source of catalytic sites. Traditional polymer-to-fuel routes often need precious-metal catalysts, organic solvents, or an outside hydrogen feed. This run used none of those, and it stayed far below the heat of pyrolysis.

Oak Ridge has worked with molten salts since the 1960s Molten Salt Reactor Experiment, which tested salt mixtures as nuclear fuel and coolant. Dai proposed putting that chemistry on discarded polymer instead. Tomonori Saito, who managed the project, said the aim was fundamental science on a widely available commodity polymer, and the economic openings that might follow.

What the Molten Salt Does to Polyethylene

The mix is not a fancy catalyst bed. It is a liquid salt that is both the solvent and the acid. Soft X-ray spectroscopy and nuclear magnetic resonance showed that charged aluminum atoms bind to three other atoms, creating strongly acidic sites that cut the long polyethylene chains into shorter hydrocarbons.

Unlike traditional techniques for converting polymer to fuel, the new process did not require noble-metal catalysts, organic solvents or external hydrogen. This is the first time molten salts were used as media to produce high-value-added chemicals from waste without any catalytic initiator or solvent and at a temperature below 200 degrees Celsius.

Zhenzhen Yang, Oak Ridge staff scientist

When a polyethylene chain meets an aluminum site, it forms a positively charged carbon ion. Qiu, Yang, and Dai tagged that ion with deuterium so they could follow it. Neutrons at Oak Ridge’s Spallation Neutron Source tracked hydrogen in a polymer that is full of it, Dai said, because neutrons pick out light elements and their isotopes.

Aluminum Sites Attack the Polymer Chain

Yang took the aluminum question to the Advanced Light Source at Lawrence Berkeley National Laboratory and worked there with Min-Jae Kim and Jinhua Guo. Soft X-rays showed the aluminum edge shifting toward lower electron density, which she read as electron-rich intermediates forming. The team compared that shift with other methods and concluded that an aromatic ring intermediate can coordinate with aluminum and change the binding energy, evidence the aluminum sites were doing catalytic work.

Bobby Sumpter of the Center for Nanophase Materials Sciences simulated the energy path, including how stable carbon ions form and move into hydrocarbon products. The paper describes a sequence of hydride abstraction, beta-scission, isomerization, and internal hydrogen transfer with AlCl3 as the active site. Tricoordinated Al3+ is the working form, with Lewis acidity the authors compare to the aluminum in an acidic zeolite, and the ionic melt helps stabilize the carbenium intermediates.

Simpler Chains Lean Toward Gasoline

Isotopic labeling and neutron scattering showed that chain shape steers the product. Simpler polymer chains tended to give gasoline-like compounds. More complex chains leaned toward diesel-like fuels. Luke Daemen used neutron scattering to identify those products, and Felipe Polo-Garzon separated them by gas chromatography-mass spectrometry.

The parameter sweep is blunt about heat and salt ratio. At 150 degrees Celsius in AlCl3/NaCl at a 2:1 molar ratio for five hours, liquid alkane yield was 29 percent. Raising the heat to 170 degrees Celsius lifted that figure to 63 percent. At 180 degrees Celsius the yield was 61 percent, a small drop. Switching the salt ratio to 3:1 cut the yield to 31 percent, which the authors tie to a higher melting range, stronger Lewis acidity, poorer polyethylene solubility, over-cracking, and carbon byproduct.

YIELD AGAINST HEAT AND SALT RATIO

Oak Ridge’s technology record for invention 202505917 describes a one-pot polyethylene conversion without hydrogen, solvents, or metal catalysts, and says the same medium can handle high-molecular-weight plastics that usually resist chemical recycling. The authors have applied for a patent. Qiu said polymer waste is abundant and the aluminum molten salts are very cheap, and that the advance may be promising for industry.

A Long Line of Plastic-to-Oil Plants

Plastic-to-fuel is not a new industrial idea. The usual plant tool is pyrolysis, which breaks polymers in the absence of oxygen at high heat. Oak Ridge puts those older polyethylene-to-gasoline routes at roughly 450 to 500 degrees Celsius, 280 to 330 degrees hotter than the 170 degrees Celsius optimum in this melt. Yang’s line about a temperature below 200 degrees Celsius is the comparison Oak Ridge has used to a kitchen oven.

The aluminum chloride molten salts as catalyst also skip the initiator that earlier catalytic systems needed to start. Dai said a stable system can be radically easier to scale, and that this one does not need that kickoff chemical. Those are lab advantages measured against heat, hydrogen, and precious metals. They are not a plant.

LAB MELT VERSUS PYROLYSIS HEAT

Lee Hodder, managing director for carbon capture and circular solutions at Viridor, said the underlying pyrolysis technology does work and that Quantafuel reached around 70 to 75 percent yield of pyrolysis oil by weight. That oil yield is higher than the 63 percent liquid alkanes in the Oak Ridge flask, and it was still not enough to keep those sites open.

Chemical Recycling Hit a Wall in 2026

The plants that already sell this family of chemistry have been shrinking, not filling. Chemically recycled material made up 0.2 percent of European plastics production in 2024, on Plastics Europe’s circular-economy figures, and 0.1 percent of global plastics production, a smaller share on a larger base. Global plastics output was 430.9 million tonnes in 2024 on the group’s facts set.

Europe’s circular share, which folds in mechanical recycling, chemical recycling, and bio-based feedstock, was 15.8 percent of production in 2024, or 8.7 million tonnes. Growth in that circular slice slowed to 1.2 percent. Of collected plastic waste, 70.4 percent of collected plastic waste still went to landfill or incineration, and 29.6 percent was recycled.

THE 2026 CONTRACTION

• Viridor: Closed its three Quantafuel sites in Scandinavia after saying the sector was not commercially viable, even with a 70 to 75 percent pyrolysis-oil yield.
• Plastic Energy: A UK chemical-recycling firm went into administration in 2026; joint administrator Geoff Rowley said it could not operate sustainably in a European downturn, while two Spanish plants sat outside the insolvency.
• Pipeline: Analysis by the Fraunhofer Institute for Environmental, Safety, and Energy Technology put Europe’s chemical-recycling capacity at 289,000 tonnes a year before the Quantafuel closure, with 65 projects in the pipeline and nine already cancelled.
• Offtake: Hodder said these builds cost hundreds of millions of dollars and need regulatory certainty before buyers will sign multi-year contracts.

Maria Vera Duran, policy director at Recycling Europe, said the closures sit inside a broader structural crisis for both mechanical and chemical recycling in Europe. The first posts that spread the Oak Ridge note treated bags-to-gasoline as an industrial answer sitting on the shelf. They did not mention that pyrolysis oil at higher yield has already met a market that would not pay for it.

Hygroscopic Salts and a Wet Plant Floor

The remaining lab problem is ordinary moisture. Oak Ridge says the aluminum-site system is catalytically active and inexpensive, and that it is hygroscopic, so it absorbs water and loses stability. Anhydrous aluminum chloride has a well-documented hygroscopic nature of aluminum chloride in chemical handbooks; it takes up water aggressively, and wet handling is a known industrial headache for anyone who uses it as a Lewis acid.

A shopping-bag stream is not a dry flask. Post-consumer polyethylene arrives with food film, ink, labels, and humidity. A salt that fails when it drinks water is a plant-design problem before it is a chemistry problem. The authors want to confine the molten salts, possibly with halogens or carbon-based materials, to make separation easier and to keep the melt stable.

Dai’s claim that a stable system is easier to scale is the right test, and it is the test they have not yet passed. The cheap part of the recipe is also the wet part. Until the salt can be boxed, dried, and reused, the 63 percent yield stays a batch result at 170 degrees Celsius, not a barrel of gasoline.

Seventeen Months After Publication, the Headlines Arrive

The calendar is part of the story. The chemistry is not a September 2026 invention. It is a 2025 paper being read again while the industrial cousins of this idea are shutting doors.

FROM THE PAPER TO THE SECOND WAVE

1. April 7, 2025: The Journal of the American Chemical Society posts the paper online, DOI 10.1021/jacs.5c01107.
2. May 14, 2025: The article runs in volume 147, issue 19, pages 16207 to 16216, under the title Polyethylene Upcycling to Liquid Alkanes in Molten Salts under Neat and External Hydrogen Source-Free Conditions.
3. April 8, 2026: Oak Ridge publishes its news note and points to patent file 202505917.
4. 2026: Viridor closes the three Quantafuel sites and Plastic Energy enters administration, while Fraunhofer’s map still shows a thin European chemical-recycling base.
5. September 21, 2026: A fresh round of summaries repeats the Oak Ridge note and the 170 degrees Celsius, no-hydrogen frame.

The Department of Energy’s Office of Science paid for the core work through its Materials Sciences and Engineering Division, with extra support for the gas chromatography-mass spectrometry from the Catalysis Science program. The Spallation Neutron Source, the Center for Nanophase Materials Sciences, and Berkeley’s Advanced Light Source supplied the instruments. That is a complete lab story. It is not a fuel terminal.

Qiu still has the cheapest line in the file: the waste is abundant and the salt is cheap. The next experiment, as Oak Ridge wrote it, is to trap that salt so it stops drinking water. Until someone does, polyethylene will keep turning into fuel in a flask at 170 degrees Celsius, and the plants that already sell plastic oil will keep doing the harder arithmetic.