Abstract: Quinoline insoluble substance (QI) in high temperature coal tar is removed by solvent dilution and thermal filtration at 110 ℃, then the light components in solvent and coal tar are removed by vacuum distillation to obtain purified asphalt with moderate softening point and QI content of 0.548%. Furthermore, the content of QI in asphalt is reduced to 0.087% by mild hydrogenation process. Needle coke products are obtained by delayed coking at 500 ℃ and calcination at 1 000 ℃. Compared with a foreign product, the performance index is almost the same. The mechanism study shows that the catalytic hydrogenation of coal tar is a process of hydrogenation of unsaturated hydrocarbons, desulfurization and denitrification . After hydrogenation, the H/C atomic ratio of the system increases, and the contents of N and S elements decrease. In the further reaction, aromatics will undergo dehydrogenation, cyclization, aromatization and recombination to form polynuclear aromatic compounds with large molecular weight and thermodynamic stability, and then form planar disk-shaped condensed polynuclear aromatic compounds. Due to the space surface energy, the condensed polynuclear aromatic compounds will curl to form mesophase complex spheres, and then merge into parallel mesophase system, forming "needle like" junction under the action of air flow. Finally, the needle coke is obtained after solidification and coking.

Key words: high temperature coal tar, thermal filtration, hydrogenation, needle coke