Synthesis and structural evolution of coal-based mesophase pitch by hydrogenation-vacuum thermal polycondensation process

Abstract

As high-performance carbon materials precursor, the controlled synthesis of mesophase pitches has received widespread attention. Coal tar pitch and Tetrahydronaphthalene (THN) were selected as raw material and hydrogen supply solvent to synthesize mesophase pitches through hydrogenation and vacuum polycondensation. The compositions and structure of resultant hydrogenated and mesophase pitches were characterized and analyzed by various methods. The results revealed that the introduction of THN could effectively increase the H content in hydrogenated pitches, and the transformation of HN to Har was observed with the extension of the reaction time. The softening point of the resultant mesophase pitches was 230–245 °C, the Mn ranged from 1400 to 2000 Da, the anisotropic content was up to 96 %, and the contents of the four subfractions were THFI > HI-TS > HS > TI-THFS in descending order. This work provided an efficient and convenient approach for the synthesis of mesophase pitches, with a view to providing a theoretical and practical foundation for spinning-grade mesophase pitch preparation.