Study on Chemical Structure of Meso-Carbon Microbeads Made from Coal-Tar Pitches by ¹³C-NMR and ESR Methods

Abstract

The ¹³C-NMR (Nuclear Magnetic Resonance) and ESR (Electron Spin Resonance) analyses were applied to four kinds of coal-tar pitches as raw material, and to the fractions of toluene insolublequinoline soluble (β-resin) and quinoline insoluble (QI) which were components of meso-carbon microbeads (MCMB) prepared from the heat-treatment of raw materials.
It should be noted that QI had higher average molecular weight and more developed aromatic ring structure than β-resin, while QI and β-resin had almost the same aromaticity. Therefore, it was plausible that the change from raw material to β-resin was mainly caused by the increase of aromaticity, while the change from β-resin to QI was mainly caused by the development of aromatic ring structure. Furthermore, the content of bridged carbon locating between two aromatic rings was markedly reduced by the heat-treatment. It was found out that the yield and development of aromatic ring structure of MCMB were positively correlated with the average molecular weight and the content of bridged carbon of raw material as well.