Modified pitch A (MPA) and modified pitch B (MPB) were prepared by oxidative polymerization and thermal polycondensation reaction with refined pitch as the raw material, respectively. The toluene soluble components (TS-1 and TS-2) were obtained by solvent extraction from MPA and MPB, separately. The Flynn-Wall-Ozawa method and Kissinger-Akahira- Sunose method were used to calculate the pyrolysis activation energy of TS. The Satava- Sestak method was used to investigate the pyrolysis kinetic parameters of TS. Moreover, the optical microstructure of the thermal conversion products (TS-1-P and TS-2-P) by calcination shows that TS-1-P has more contents of mosaic structure and lower contents of fine fiber structure than TS-2-P. The research result obtained by a combination of X-ray diffraction and the curve-fitting method revealed that the ratios of ordered carbon crystallite (Ig) in TS-1-P and TS-2-P were 0.3793 and 0.4417, respectively. The distributions of carbon crystallite on TS-1-P and TS-2-P were calculated by Raman spectrum and curve-fitting analysis. They show that the thermal conversion product of TS-2 has a better graphite crystallite structure than TS-1.

Abstract
 1. Introduction
 2. Experimental
  2.1. Production and properties of TS
  2.2. Preparation of thermal conversion products
  2.3. TG/DTG analysis of TS
  2.4. Kinetic approach
  2.5. Characterization of thermal conversion products
 3. Results and Discussion
  3.1. Thermogravimetric analysis results
  3.2. Activation energy calculated by FWO and KAS methods
  3.3. Kinetics parameters calculated by Satava-Sestak method
  3.4. Polarized microscopic structure analysis of thermal conversion products
  3.5. XRD analysis results of thermal conversion products
  3.6. Raman spectrum analysis of thermal conversion products
 4. Conclusions
 References

• Yaming Zhu(Engineering Research Center of Advanced Coal Coking and Efficient Use of Coal Resources, University of Science and Technology Liaoning)
• Xuefei Zhao(Engineering Research Center of Advanced Coal Coking and Efficient Use of Coal Resources, University of Science and Technology Liaoning) Corresponding Author
• Lijuan Gao(Engineering Research Center of Advanced Coal Coking and Efficient Use of Coal Resources, University of Science and Technology Liaoning)
• Junxia Cheng(Engineering Research Center of Advanced Coal Coking and Efficient Use of Coal Resources, University of Science and Technology Liaoning)