QST achieves complete decomposition of Teflon by irradiation and heating — CO₂ emissions reduced by half compared to conventional methods

A research group led by Senior Researcher Akira Idesaki and Project Leader Yue Zhao from the Nanostructured Polymer Materials Project, Department of Advanced Functional Materials Research, Takasaki Institute for Advanced Quantum Science (TIAQ), National Institutes for Quantum Science and Technology (QST), announced on July 24 that they successfully achieved complete decomposition of Teflon (PTFE), which is difficult to recycle, by treating it with a combination of irradiation and heating, while reducing CO₂ emissions by half compared with conventional high-temperature pyrolysis methods. They aim to develop separation methods for decomposition products and scale up in the future. This is expected to lead to recycling technology that achieves both resource security and CO₂ emission reduction. The results were published in the June 3 issue of Radiation Physics and Chemistry.

Fluoropolymers such as PTFE have extremely high mechanical, chemical, and thermal stability and are widely used in products from industrial to household applications. They are made using fluorspar or hydrogen fluoride as raw materials, which are converted to organic fluorine compounds, and then processed into products.

On the other hand, these raw materials are almost entirely dependent on imports, and CO₂ emissions during the manufacturing process from raw materials to resin are higher compared with other plastics and resins, resulting in a high environmental burden.

Due to their high stability, recycling is difficult, and even in Europe, where fluorine waste recycling is more advanced than in Japan, chemical recycling remains at only a few percent. The government also strongly demands recycling of end-of-life plastics, including PTFE, in its plastic resource circulation strategy.

Moreover, the decomposition of end-of-life fluoropolymers currently being tested requires high-temperature heat treatment of 600-1000℃, making high costs a challenge.

In this study, the research group considered developing technology to decompose PTFE into organic fluorine compounds through electron beam irradiation, a type of radiation, based on the fundamental knowledge of radiation reactions with fluoropolymers that they have accumulated. They aimed for a simpler process and reduction of required energy amounts. Organic fluorine compounds are materials present just before resin synthesis in fluoropolymer manufacturing and processing, with diverse applications such as refrigerator refrigerants, and are in high demand.

Initially, the group considered a method of adding catalysts and performing electron beam irradiation. Although the decomposition start temperature could be lowered to 103℃, the decomposition end temperature remained close to 600℃, resulting in low energy reduction effects.

Therefore, they devised a method of irradiating PTFE with electron beams while heating. They investigated the progress of decomposition at each temperature by varying temperature conditions. As a result, they confirmed that heating to 370℃ in air and irradiating with 5 MGy electron beams achieved complete decomposition, with all solid samples completely vaporizing.

By examining the gases obtained, they also found that C₄F₄, useful fluorocarbon gases, and oxide gases that reacted with oxygen in the air were obtained.

In addition, they confirmed that complete decomposition, which conventionally required 4200 kW/h with high-temperature heating, was accomplished at 2170 kW/h, half this figure. In terms of CO₂ generation, they confirmed that emissions could be suppressed to 920 kilograms from the conventional 1780 kilograms per ton of processing.

In this research, complete decomposition of about 1 gram of powder sample required approximately 1.5 hours. The group aims for further optimization of conditions in the future.

Idesaki commented: "In this research, we first focused on decomposition, but we believe the biggest challenge going forward is scaling up. To overcome this challenge, we hope to advance research in collaboration with companies that have know-how and technology related to fluoropolymer manufacturing and recycling. Currently, we assume the decomposition target to be pellets that have been sorted to some extent, but we also plan to accumulate basic data on what products can be obtained in mixed states with resins. If gases can be separated, we think pre-processing may become unnecessary."

Journal Information
Publication: Radiation Physics and Chemistry
Title: Effects of temperature on the decomposition of PTFE induced by electron beam irradiation
DOI: 10.1016/j.radphyschem.2025.113029