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PreprintCC BY-NCChemRxiv

Mechanochemical Birch-type hydrodefluorination of polytetrafluoroethylene: amine-controlled hydrogenation versus carbonization

  • Masashi Hattori1,2
  • Hibiki Ota3,2
  • Moe Fujishiro4
  • Kanako Inoo4
  • Yosuke Kishikawa4
  • Zhengyu Zhao3,2
  • Norio Shibata3,2
4 affiliations
  1. 1Department of Nanopharmaceutical Sciences
  2. 2Nagoya Institute of Technology, Gokiso
  3. 3Department of Life Science and Applied Chemistry
  4. 4Technology and Innovation Center, DAIKIN Industries, Ltd, 1-1 Nishi-Hitotsuya, Settsu, Osaka, Japan
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Abstract

Reductive defluorination of polytetrafluoroethylene (PTFE) can efficiently recover fluoride but commonly converts the carbon component into poorly defined carbonaceous solids. Herein, we report a mechanochemical Birch-type hydrodefluorination using lithium and ethylenediamine (EDA) that couples C-F bond cleavage with hydrogen incorporation. Milling at 30 Hz and room temperature released fluoride in 98% yield within 10 min, as independently determined by quantitative 19F NMR spectroscopy and ion chromatography. The pale-brown residue contained 0.6 wt% fluorine, 78.4 wt% carbon, and 12.3 wt% hydrogen, corresponding to an atomic H/C ratio of 1.88. FTIR and Raman spectroscopy, differential scanning calorimetry, solid-state 13C-MAS NMR, and powder X-ray diffraction showed loss of the PTFE C-F fingerprint and emergence of a CH2-rich structure with polyethylene-like thermal and crystalline features. The product is therefore assigned as a polyethylene-like material rather than chemically pure polyethylene. In the absence of EDA, fluoride was again obtained in 98% yield, whereas the solid product was a black, disordered sp2rich carbon. Coarser PTFE powders likewise tended to afford darker solids despite nearly quantitative fluoride recovery. These results demonstrate that fluoride yield alone is not a measure of hydrodefluorination selectivity and that EDA controls the competition between hydrogen incorporation and carbonization. The method converts PTFE into an inorganic fraction containing LiF and a hydrogen-rich carbon material potentially suitable for downstream polyolefin valorization.

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Cite

BibTeXRIS
BibTeX
@misc{hattori2026mechanochemical,
  title = {{Mechanochemical Birch-type hydrodefluorination of polytetrafluoroethylene: amine-controlled hydrogenation versus carbonization}},
  author = {Masashi Hattori and Hibiki Ota and Moe Fujishiro and Kanako Inoo and Yosuke Kishikawa and Zhengyu Zhao and Norio Shibata},
  howpublished = {ChemRxiv},
  year = {2026},
  month = sep,
  doi = {10.26434/chemrxiv.15009230/v1},
  url = {https://chemrxiv.org/doi/full/10.26434/chemrxiv.15009230/v1},
  note = {CC BY-NC},
}
RIS
TY  - UNPB
TI  - Mechanochemical Birch-type hydrodefluorination of polytetrafluoroethylene: amine-controlled hydrogenation versus carbonization
AU  - Masashi Hattori
AU  - Hibiki Ota
AU  - Moe Fujishiro
AU  - Kanako Inoo
AU  - Yosuke Kishikawa
AU  - Zhengyu Zhao
AU  - Norio Shibata
PY  - 2026
DA  - 2026/09/22
PB  - ChemRxiv
DO  - 10.26434/chemrxiv.15009230/v1
UR  - https://chemrxiv.org/doi/full/10.26434/chemrxiv.15009230/v1
AB  - Reductive defluorination of polytetrafluoroethylene (PTFE) can efficiently recover fluoride but commonly converts the carbon component into poorly defined carbonaceous solids. Herein, we report a mechanochemical Birch-type hydrodefluorination using lithium and ethylenediamine (EDA) that couples C-F bond cleavage with hydrogen incorporation. Milling at 30 Hz and room temperature released fluoride in 98% yield within 10 min, as independently determined by quantitative 19F NMR spectroscopy and ion chromatography. The pale-brown residue contained 0.6 wt% fluorine, 78.4 wt% carbon, and 12.3 wt% hydrogen, corresponding to an atomic H/C ratio of 1.88. FTIR and Raman spectroscopy, differential scanning calorimetry, solid-state 13C-MAS NMR, and powder X-ray diffraction showed loss of the PTFE C-F fingerprint and emergence of a CH2-rich structure with polyethylene-like thermal and crystalline features. The product is therefore assigned as a polyethylene-like material rather than chemically pure polyethylene. In the absence of EDA, fluoride was again obtained in 98% yield, whereas the solid product was a black, disordered sp2rich carbon. Coarser PTFE powders likewise tended to afford darker solids despite nearly quantitative fluoride recovery. These results demonstrate that fluoride yield alone is not a measure of hydrodefluorination selectivity and that EDA controls the competition between hydrogen incorporation and carbonization. The method converts PTFE into an inorganic fraction containing LiF and a hydrogen-rich carbon material potentially suitable for downstream polyolefin valorization.
ER  -