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<p>The scope of this study is to investigate the effect of swelling with different polar solvents, including tetrahydrofuran (THF), benzene (BE) and <i>n</i>-heptane (Hep), on the pyrolysis properties of low-rank coal and the possible formation pathways of phenols. In this paper, swelled de-ashed vitrinite (VD-S: VD-THF, VD-BE and VD-Hep) and swelled de-ashed inertinite (ID-S: ID-THF, ID-BE and ID-Hep) were prepared and characterized by FTIR. The weight loss and kinetic analysis were investigated using thermogravimetry (TG), and the distribution of pyrolysis products were investigated by Py-GC/MS and fast pyrolysis fixed bed. Combining the selectivity changes of pyrolysis products with density functional theory (DFT) calculations, the possible formation pathways of phenols derived from VD-S and ID-S pyrolysis are proposed. TG results show that the weight loss of VD-THF and ID-THF reaches up to 32.22 wt% and 26.48 wt%. The comparison of activation energy exhibits that THF primarily affects the first stage of pyrolysis. The highest selectivity of PCXC was observed in VD-THF and ID-THF, at up to 19.99% and 17.40%. By integrating the selectivity changes of the detected compounds using Py-GC/MS with the comprehensive analysis of electrostatic potential (ESP) and frontier molecular orbital, seven possible formation pathways of cresol preparation by VD-S and ID-S are proposed. DFT calculations demonstrate that Path 5 of VD-Hep possesses the lowest reaction energy of 140.79&#xa0;kJ/mol. Ultimately, the possible swelling mechanism exhibits that the C<sub>ar</sub>–C<sub>al</sub> bonds are prone to cracking when macerals are swelled by BE. THF promotes the cleavage of C–O bonds, and Hep affects the cleavages of C<sub>al</sub>–C<sub>al</sub> bonds.</p>

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Formation mechanism of phenols during pyrolysis of low-rank coal macerals swelled with different polar solvents based on Py-GC/MS and DFT analysis

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  • 发表日期：

    2026年7月27日

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  • Qiuxiang Yao,
  • Linyang Wang,
  • Qiuyu Jin,
  • Rui Cao,
  • Lei He,
  • Zongcheng Miao,
  • Ming Sun,
  • Xiaoxun Ma

摘要

The scope of this study is to investigate the effect of swelling with different polar solvents, including tetrahydrofuran (THF), benzene (BE) and n-heptane (Hep), on the pyrolysis properties of low-rank coal and the possible formation pathways of phenols. In this paper, swelled de-ashed vitrinite (VD-S: VD-THF, VD-BE and VD-Hep) and swelled de-ashed inertinite (ID-S: ID-THF, ID-BE and ID-Hep) were prepared and characterized by FTIR. The weight loss and kinetic analysis were investigated using thermogravimetry (TG), and the distribution of pyrolysis products were investigated by Py-GC/MS and fast pyrolysis fixed bed. Combining the selectivity changes of pyrolysis products with density functional theory (DFT) calculations, the possible formation pathways of phenols derived from VD-S and ID-S pyrolysis are proposed. TG results show that the weight loss of VD-THF and ID-THF reaches up to 32.22 wt% and 26.48 wt%. The comparison of activation energy exhibits that THF primarily affects the first stage of pyrolysis. The highest selectivity of PCXC was observed in VD-THF and ID-THF, at up to 19.99% and 17.40%. By integrating the selectivity changes of the detected compounds using Py-GC/MS with the comprehensive analysis of electrostatic potential (ESP) and frontier molecular orbital, seven possible formation pathways of cresol preparation by VD-S and ID-S are proposed. DFT calculations demonstrate that Path 5 of VD-Hep possesses the lowest reaction energy of 140.79 kJ/mol. Ultimately, the possible swelling mechanism exhibits that the Car–Cal bonds are prone to cracking when macerals are swelled by BE. THF promotes the cleavage of C–O bonds, and Hep affects the cleavages of Cal–Cal bonds.