Ethylene tar pitch (ETP), primarily derived from the residues of carbon black production and naphthalene purification in ethylene tar processing, is a polycyclic aromatic hydrocarbon with high carbon content and low ash content. It is considered a promising precursor for high-quality synthetic carbon materials. Thermal conversion is a critical step in the preparation of pitch-based carbon materials, as it largely determines the final structural quality of the carbon product. In this study, ETP was selected as the research subject, and a combination of analytical techniques, including group composition analysis, elemental analysis, Fourier Transform Infrared Spectroscopy (FTIR), polarized optical microscopy (POM), Raman spectroscopy, and X-ray diffraction (XRD) were employed to investigate the evolution of the average molecular structure and carbon microstructure during the thermal conversion process. The results indicate that with increasing thermal conversion temperature and duration, the degree of aromatic condensation in the ETP-derived products gradually increases. Simultaneously, the internal carbon microcrystals become more ordered and larger in size. Notably, when the thermal conversion temperature reaches 480 °C, the aromaticity index (Iar) sharply increases to 0.42, and anisotropic structures begin to appear under POM. This suggests that 480 °C is a critical temperature point at which ETP undergoes intensified thermal polycondensation and exhibits enhanced molecular reactivity. This study provides both theoretical and experimental support for the efficient utilization of ETP in the production of advanced carbon materials.

Study on thermal conversion behaviors of ethylene tar pitch
    Abstract
    Highlights
    1 Introduction
    2 Experiments and methods
        2.1 Experimental materials
        2.2 Thermal conversion of ethylene tar pitch
        2.3 Characterisation
            2.3.1 Composition analysis and elemental analysis
            2.3.2 Fourier transform infrared spectroscopy
            2.3.3 Polarized optical microscope analysis
            2.3.4 Raman spectroscopy analysis
            2.3.5 X-Ray diffraction (XRD) analysis
            2.3.6 Thermogravimetric analysis
    3 Results and discussion
        3.1 Yield analysis of ETP thermal conversion product
        3.2 Elemental analysis of ETP thermal conversion products
        3.3 Group composition analysis of ETP thermal conversion products
        3.4 FTIR analysis of ETP thermal conversion products
        3.5 POM-based microstructural observation of ETP thermal conversion residues
        3.6 Raman spectroscopy analysis of ETP thermal conversion products
        3.7 XRD analysis of ETP thermal conversion products
        3.8 Thermogravimetric analysis of ETP thermal conversion products
        3.9 Proposed mechanism for the thermal conversion behavior of ETP
    4 Conclusion
    References

• Yuan Qi(School of Chemical Engineering, University of Science and Technology Liaoning, Anshan 114051, China)
• Yuzhu Zhang(School of Chemical Engineering, University of Science and Technology Liaoning, Anshan 114051, China)
• Yaming Zhu(School of Chemical Engineering, University of Science and Technology Liaoning, Anshan 114051, China) Corresponding author
• Huihui Zhu(School of Chemical Engineering, University of Science and Technology Liaoning, Anshan 114051, China)
• Junxia Cheng(School of Chemical Engineering, University of Science and Technology Liaoning, Anshan 114051, China)
• Xuefei Zhao(School of Chemical Engineering, University of Science and Technology Liaoning, Anshan 114051, China)