Preparation and characterization of high softening point and homogeneous isotropic pitches produced from distilled ethylene tar by a novel bromination method

Homogeneous isotropic pitches with high softening points were prepared from vacuum-distilled heavy residue ethylene tar (ET-HR) by a two-step method of bromination and subsequent dehydrobromination/poly-condensation. The ET-HR was first brominated at 30 or 200 °C, and then heat-treated at 350 °C to...

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Bibliographic Details
Published in:Carbon (New York) 2018-08, Vol.134, p.537-537
Main Authors: Ge, Chuan-zhang, Sun, Zhen-long, Yang, Hai-xiao, Long, Dong-hui, Qiao, Wen-ming, Ling, Li-cheng
Format: Article
Language:English
Subjects:
Aliphatic compounds
Anisotropy
Aromatic compounds
Bromination
Bromine
Coking
Condensation
Ethylene
Heat treatment
Infrared radiation
NMR
Nuclear magnetic resonance
Polycondensation reactions
Prepolymers
Softening
Softening points
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Summary:Homogeneous isotropic pitches with high softening points were prepared from vacuum-distilled heavy residue ethylene tar (ET-HR) by a two-step method of bromination and subsequent dehydrobromination/poly-condensation. The ET-HR was first brominated at 30 or 200 °C, and then heat-treated at 350 °C to enable the dehydrobromination/polycondensation reactions. GC/MS and LDI TOF/MS spectra indicated that the ET-HR was mainly composed of compounds containing 3- to 6-ring aromatic species with a considerable aliphatic chain content. Compared with thermal condensation alone, such a two-step method increased the softening point of the pitches from 152 to 264 °C with a yield in the range of 62-67 wt% and a coking value in the range of 57-77 wt.%, depending on the bromination temperature and the bromine content. Structural character-ization of the as-prepared pitches by elemental analysis, 1H NMR, FT-IR and LDI-TOF/MS showed increased aromatization and polymerization of the precursor during the dehydrobromination/polycondensation. All the homogeneous isotropic pitches showed an ability to transform into an anisotropic texture after coking at 800 °C.
ISSN:0008-6223
1873-3891
DOI:10.1016/j.carbon.2018.02.016