关键词: 萘沥青, 离子液体, 溶液萃取, 分离, 中间相沥青

Abstract:

To address the drawbacks of the alkaline solution treatment method in separating naphthalene pitch from chloroaluminate ionic liquids catalyst, such as the destruction of the ionic liquid structure and the generation of a large amount of waste alkaline solution, liquid-liquid extraction with xylene was adopted to separate the naphthalene pitch in the naphthalene polymerization reaction mixture, and the extraction and separation performance were studied. The results show that the naphthalene pitch components with small molecular weights and high aromaticity are preferentially extracted. After five consecutive extractions, 70% of the naphthalene pitch in the naphthalene polymerization reaction mixture is extracted. Only a small amount of entrapped chloroaluminate ionic liquids need to be treated with alkaline washing and water washing, and the ash value of the naphthalene pitch can be reduced to 0.0016%. Moreover, the chloroaluminate ionic liquids in the raffinate phase can be reused. Compared with the traditional alkaline solution treatment method, this method could give naphthalene pitch with the characteristics of smaller molecular weight, more concentrated distribution, and lower softening point. By using it as a precursor, high-quality mesophase pitch with an anisotropic component content as high as 99% can be prepared.

Key words: naphthalene pitch, ionic liquid, solvent extraction, separation, mesophase pitch