Effect of Coal Tar Components and Thermal Polycondensation Conditions on the Formation of Mesophase Pitch.

This study focuses on the preparation of mesophase pitch via the thermal polycondensation of heavy components from low-temperature coal tar. By altering the coal tar composition through distillation, we investigated the impact of various coal tar components and reaction conditions on the properties of the resulting mesophase pitch. Techniques such as infrared spectroscopy, nuclear magnetic resonance, optical structure analysis, and family-component analysis were employed to analyze both the coal tar and mesophase pitch. The primary objective was to provide a comprehensive understanding of mesophase pitch preparation and the underlying transformation mechanisms of coal tar at the molecular, chemical, and functional group levels. Our findings revealed that mesophase pitch formation was driven by a combination of chemical reactions and physical processes. Increasing the distillation temperature reduced the number of alkyl substituents, shortened chain lengths, and promoted greater aromatic condensation. The optimal mesophase pitch content was achieved at a distillation temperature of 360 °C, a reaction temperature of 400 °C, and a holding time of 12 h, resulting in a predominantly inlaid structure. This work addresses a gap in the understanding of coal tar transformation, highlighting how the interplay between distillation temperature and reaction conditions affects the structural properties of mesophase pitch, with implications for improving its production and applications in carbon materials.