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February 6, 2025

Recycling the unrecyclable: New method reclaims materials from epoxy resins and composites

This image from a scanning electron microscope shows the quality of carbon fibers recovered from the decomposition process. Credit: 2025 Jin et al. CC-BY-ND
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This image from a scanning electron microscope shows the quality of carbon fibers recovered from the decomposition process. Credit: 2025 Jin et al. CC-BY-ND

Epoxy resins are coatings and adhesives used in a broad range of familiar applications, such as construction, engineering and manufacturing. However, they often present a challenge to recycle or dispose of responsibly.

For the first time, a team of researchers, including those from the University of Tokyo, developed a method to efficiently reclaim materials from a range of epoxy products for reuse by using a novel solid catalyst. The work has been in Nature Communications.

There's a high chance you are surrounded by epoxy compounds as you read this. They are used in due to their insulating properties; clothing such as shoes due to their binding properties and physical robustness; for the same reason; and even in aircraft bodies and wind turbine blades for their ability to contain strong materials such as carbon fibers or glass fibers.

It's hard to overstate the importance of epoxy products in the modern world. But for all their uses, they inevitably have a downside: Epoxy compounds are essentially plastics and prove difficult to deal with after their use or at the end of the life of an epoxy-containing product.

"For example, to decompose fiber-reinforced plastics, perhaps used in aircraft parts, you'd need high temperatures over 500 degrees Celsius, or strong acid or base conditions. These things have an energy cost, and the can damage the fibers and things you might be trying to recover," said Associate Professor Xiongjie Jin at the University of Tokyo.

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"To deal with this problem, a relatively new process called catalytic hydrogenolysis shows promise, but existing catalysts for this are not reusable as they dissolve in the solvent in which the epoxy decomposition takes place. So, we created a new solid catalyst which is easily recoverable and reusable."

This might look like something you'd see on the floor of a barber's shop, but it's actually a clump of reclaimed carbon fibers. Credit: 2025 Jin et al. CC-BY-ND
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This might look like something you'd see on the floor of a barber's shop, but it's actually a clump of reclaimed carbon fibers. Credit: 2025 Jin et al. CC-BY-ND

Jin and Professor Kyoko Nozaki, both from the Department of Chemistry and Biotechnology, and their team developed an efficient and robust catalyst to decompose epoxy compounds into , glass fibers and , which are important raw materials in the chemical industry.

The catalyst is referred to as bimetallic as it uses two metals, nickel and palladium, which are supported on cerium oxide and work together to mediate reactions between and hydrogen gas.

Though the reaction temperature needs to be at around 180 degrees Celsius, the energy requirements are far lower than those needed to create 500-degree conditions, and the lower temperatures mean recovered materials can be reused.

"We were pleased to see experimental results that closely matched our expectations about how this process would work, but we were nicely surprised when we realized the catalyst could be reused at least five times without any reduction in its performance," said Jin.

"As our catalyst is effective at cleaving carbon-oxygen bonds, with modification, it might even work with other plastics as well, as they contain those bonds too."

The team is now keen to explore ways to improve its methods and materials, though, as it may still take some development to make it a more commercially viable option.

"Although our catalyst does not require such high temperatures, there is still room for improvement in the environmental impact of the solvent we are currently using," said Nozaki.

"We would also like to bring the cost down by finding a that does not contain a precious metal such as palladium. It might also be possible to increase the range of materials which could be recovered from various epoxy compounds, reducing the environmental overheads of these incredibly versatile and useful plastics."

More information: Bimetallic synergy in supported Ni−Pd catalyst for selective hydrogenolysis of C−O bonds in epoxy resins, Nature Communications (2025). .

Journal information: Nature Communications

Provided by University of Tokyo

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A new method has been developed to efficiently reclaim materials from epoxy resins using a novel solid catalyst composed of nickel and palladium on cerium oxide. This catalyst facilitates the decomposition of epoxy compounds into reusable materials like carbon fibers and phenolic compounds at lower temperatures, around 180°C, compared to traditional methods. The catalyst is reusable, maintaining performance over multiple cycles, and may be adaptable for other plastics. Further improvements aim to reduce environmental impact and costs by exploring alternatives to precious metals like palladium.

This summary was automatically generated using LLM.