Comparative study of the carbonization process and structural evolution during needle coke preparation from petroleum and coal feedstock

Abstract To explore the carbonization behavior and structural evolution of needle coke prepared from different types of rich-aromatic materials, petroleum feedstock hydrocracking tail oil (HCTO) and coal feedstock low-temperature coal tar (LCT) were selected to prepare needle coke. The detailed comparative investigation focused on the properties of feedstocks and the structure of the derived needle cokes by using gas chromatography-mass spectrometry (GC-MS), 1H nuclear magnetic resonance (1H-NMR), 13C nuclear magnetic resonance (13C-NMR), polarizing microscope, thermogravimetric analysis (TGA), 13C solid-state nuclear magnetic resonance (13C-ssNMR) and Raman spectra. It was found that the colloids in LCT3 accelerated the growth and evolution of carbonaceous structure and were not conducive to the preparation of needle coke. In addition, phenols in LCT3 led to oxygen-containing crosslinking during the secondary pyrolysis, which resulted in the spatial configuration of poor planarity and wider fringe spacing in optical texture. The calcination process further enlarged the structural defects of pyrolysis products, the steric hindrance and structural strains were aggravated as well.