Tailor-made C-Cl bond towards rapid homogeneous stabilization of low-softening-point coal tar pitch

Abstract

Stabilization is of important for maintaining microstructure and morphology of pitch-based carbon materials as well as strengthening their mechanical performances, but there is a tough challenge to achieve a rapid homogeneous stabilization. Herein, a chemical bond engineering strategy is proposed for the rapid homogeneous stabilization of low-softening-point coal tar pitch (CTP) based on the introduction of C-Cl bond through the Friedel-Crafts reaction. It is suggested that the modified CTP rich in tailor-made C-Cl bonds exhibit both of well plasticity and high oxidation activity. Substantial additional free radicals are generated by the decomposition of tailor-made C-Cl bonds above 200 °C, which significantly promote the molecular cross-linking reaction and thus enhance stabilization of CTP. The resultant cross-linked molecules will further undergo condensation reaction at elevated temperatures, improving the graphitization of final carbon product. Moreover, the synergistic contribution of C-Cl bonds and oxygen to the oxidation stabilization of CTP is obviously reflected in reduction of the temperature and total time used. The strategy proposed is successfully applied in the preparation of millimeter-sized spherical carbon material. The rapid homogeneous stabilization of low-softening-point CTP has been harvested at the molecular level whereby this work provides a strong guarantee for the preparation of pitch-based carbon materials at low cost.