Coal pitch mainly consists of aromatic hydrocarbons, phenolic substances, and aliphatic hydrocarbons, the macromolecular structures formed by these cyclic and chain hydrocarbons through chemical bonding possess diversity and complexity. In this study, medium- and low-temperature coal tar pitch (LCTP) served as the primary material for the production of mesophase pitch via co-carbonization with hydrogenated tail oil (HTO). Aimed to clarify the effects of different amounts of HTO addition and analyze the mechanism of introducing naphthenic and aromatic hydrocarbons on the liquid phase carbonization process. When HTO additive amount is 30%, the carbonized product with the largest content of mature graphite crystals at 25.01%, and the smallest degree of defects. The analytical mechanism demonstrates that the condensation of naphthenic hydrocarbons introduced by HTO produces hydrogen radicals, the hydrogen transfer reaction saturates a significant quantity of free radicals generated within the system, thereby impeding further rapid condensation and curing, and decreasing the viscosity of the system. On the other hand, the aromatic hydrocarbons introduced undergo dehydrogenation and condensation to produce additional polycyclic aromatic hydrocarbons, thereby contributing to a more abundant carbon structure conducive to the development of mesophase pitch. The combined effect of aromatic hydrocarbons and naphthenic hydrocarbons facilitates the slow development of the mesophase structure into a broad-area optical structure. This study provides an effective method for improving the performance of coal-based mesophase pitch, which reduces the production cost and promotes the clean and high value-added utilization of limited resources.

Effect of hydrogenated tail oil on liquid phase carbonization performance of medium- and low-temperature coal tar pitch
    Abstract
    1 Introduction
    2 Experimental
        2.1 Raw materials
        2.2 Experiment setup
        2.3 Characterization of samples
    3 Results and discussion
        3.1 Structure and physical properties of raw materials
            3.1.1 FT-IR analysis
            3.1.2 1H-NMR analysis
            3.1.3 GC–MS analysis
            3.1.4 XPS analysis
        3.2 Analysis of the pyrolysis performance of pitch
        3.3 Analysis of viscosity-temperature performance of pitch
        3.4 Analysis of structure and properties of carbonaceous mesophase
            3.4.1 Effect of co-carbonization on optical structure of mesophase
            3.4.2 Effect of co-carbonization on microcrystalline structure
            3.4.3 Effects of co-carbonization on C structure development
        3.5 Effect of HTO addition on formation and development of the mesophase in RCTP
    4 Conclusion
    Acknowledgements 
    References

• Jiaojiao Liu(School of Chemical Engineering, The Research Center of Chemical Engineering Applying Technology for Resource of Shaanxi, Northwest University, Xi’an 710069, Shaanxi, China)
• Shiquan He(School of Chemical Engineering, The Research Center of Chemical Engineering Applying Technology for Resource of Shaanxi, Northwest University, Xi’an 710069, Shaanxi, China)
• Sijie Wang(School of Chemical Engineering, The Research Center of Chemical Engineering Applying Technology for Resource of Shaanxi, Northwest University, Xi’an 710069, Shaanxi, China)
• Ting He(School of Chemical Engineering, The Research Center of Chemical Engineering Applying Technology for Resource of Shaanxi, Northwest University, Xi’an 710069, Shaanxi, China)
• Zhe Jin(School of Chemical Engineering, The Research Center of Chemical Engineering Applying Technology for Resource of Shaanxi, Northwest University, Xi’an 710069, Shaanxi, China)
• Chongpeng Du(School of Chemical Engineering, The Research Center of Chemical Engineering Applying Technology for Resource of Shaanxi, Northwest University, Xi’an 710069, Shaanxi, China)
• Yi Wang(School of Chemical Engineering, The Research Center of Chemical Engineering Applying Technology for Resource of Shaanxi, Northwest University, Xi’an 710069, Shaanxi, China)
• Dong Li(School of Chemical Engineering, The Research Center of Chemical Engineering Applying Technology for Resource of Shaanxi, Northwest University, Xi’an 710069, Shaanxi, China)
• Yonghong Zhu(School of Chemical Engineering, The Research Center of Chemical Engineering Applying Technology for Resource of Shaanxi, Northwest University, Xi’an 710069, Shaanxi, China, Hydrocarbon High-Efficiency Utilization Technology Research Center, Yanchang Petroleum Co. Ltd., Xi’an 710075, Shaanxi, China)
• Siying Xin(College of Chemistry, Sichuan University, Chengdu 610064, Sichuan, China)
• Louwei Cui(Northwest Research Institute of Chemical Industry, Xi’an 710600, Shaanxi, China)