Thermal Conversion Behavior of Medium–Low–Temperature Coal Tar Pitch During Liquid–Phase Carbonization Process

Abstract Medium–low temperature coal tar pitch (MLP) is a type of aromatic carbonaceous material obtained by the low temperature distillation of low rank coal, and is considered as a desirable raw material for the production of artificial carbon/graphite material. The thermal conversion behaviors of MLP during the liquid‐phase carbonization process were analyzed in detail in this study. Further, the changes of molecular structure and carbon microcrystalline structure of MLP and liquid‐phase carbonization products derived from it were quantitatively investigated by optical microscopy, fourier transform infrared spectroscopy, Raman spectroscopy, X‐ray diffraction, and curve‐fitting method. Results showed that both branched chain and the contents of C=O functional groups in the MLP played a key role in the reaction reactivity. Moreover, temperature of 450 °C was found to be a rapid changing temperature point on the enhancement of thermal conversion of MLP. The stacking height (L c ), parallel layers (N), average number of aromatic rings in each layer (n), ratio of ‘impurity’ structure (R I ), ratio of amorphous carbon structure (R AC ), ratio of graphite carbon structure (R GC ), and ratio of defects graphite carbon structure (R DGC ) exhibited a significant change with the improvement of liquid‐phase carbonization temperature.