Effect of raw material composition on the structure of needle coke

The refined raw material was first prepared from the low-medium temperature coal tar through hydrogenationfor 1.5h under 330–390°C and 8MPa, with a catalyst/oil mass ratioof 1/40, which was then used to produce needle coke through thermalpolymerization and calcination. The composition of refined raw materials was analyzed by elemental analysis, Fourier-transform IR spectroscopy (FT-IR) and gas chromatography-mass spectrometry (GC-MS) and the structure of needle coke was characterized by scanning electron microscope (SEM), X-ray diffractometer (XRD) and polarizing microscope; the effect of raw material composition (related to the hydrogenation temperature) on the structure of needle coke was then investigated. Theresults indicate that a proper increase in thehydrofining temperature is beneficial to the removal of heteroatoms (especially sulfur). By hydrogenation at 390°C, the aromatics in the feedstock are polarized due to the cracking and polycondensation. In addition, a highercontent of tricyclic and tetracyclic aromatics in the refined raw materials may also lead to a highergraphitization degree for the needle coke product.