Co‐Carbonization of Medium‐ and Low‐Temperature Coal Tar Pitch and Coal‐Based Hydrogenated Diesel Oil Prepare Mesophase Pitch for Needle Coke Precursor

Abstract

Herein, a better mesophase pitch as precursor for the manufacturing of green needle coke is obtained by a new process, whereas the refined medium‐ and low‐temperature coal tar pitch (RCTP) is obtained by a solvent sedimentation method, and then, it is co‐carbonized with coal‐based hydrogenated diesel oil at 420 °C for 6 h. The mesophase pitch structure is characterized by a polarized light optical microscope, Fourier transform IR (FT‐IR) spectroscopy, and 1 H nuclear magnetic resonance (NMR). The results indicate that the aromatic hydrogen content of mesophase pitch gradually increases, as the carbonization temperature increases. Also, the mesophase pitch with aliphatic side chain substitution (CH3 and CH2) is obtained at 420 °C for 2 h, which is conducive for polyaromatic hydrocarbon to the orderly accumulation. It is also a basis for preparing better green needle coke. The polarized light analysis results propose that the mesophase with a wide‐area streamlined structure is obtained at a constant temperature of 420 °C for 6 h, whose temperature and soaking time are lower than that of the high‐temperature coal tar pitch and petroleum pitch for preparing the mesophase pitch. Also, the better direction and order fiber of green needle coke with 53 % fiber are acquired.