Preparation and characterization of high softening point and homogeneous isotropic pitches produced from distilled ethylene tar by a novel bromination method
| Autor: | Donghui Long, Haixiao Yang, Wenming Qiao, Chuanzhang Ge, Zhen-long Sun, Licheng Ling |
|---|---|
| Rok vydání: | 2018 |
| Předmět: |
Bromine
Condensation polymer Ethylene Materials science Softening point 010405 organic chemistry Materials Science (miscellaneous) Aromatization chemistry.chemical_element General Chemistry 02 engineering and technology 021001 nanoscience & nanotechnology 01 natural sciences 0104 chemical sciences chemistry.chemical_compound chemistry Polymerization Proton NMR General Materials Science 0210 nano-technology Softening Nuclear chemistry |
| Zdroj: | New Carbon Materials. 33:71-81 |
| ISSN: | 1872-5805 |
| DOI: | 10.1016/s1872-5805(18)60327-0 |
| Popis: | 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/polycondensation. The ET-HR was first brominated at 30 or 200 oC, and then heat-treated at 350 oC 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 oC with a yield in the range of 62 wt. %−67 wt.% and a coking value in the range of 57 wt. %−77 wt.%, depending on the bromination temperature and the bromine content. Structural characterization 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. |
| Databáze: | OpenAIRE |
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