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

摘要：

为解决氯铝酸离子液体催化制备萘沥青过程中，碱液处理法分离萘沥青与氯铝酸离子液体所面临的离子液体结构被破坏、产生大量废碱液等诸多弊端，采用二甲苯液液萃取法对萘聚合反应混合物中的萘沥青予以分离，并研究了其萃取分离规律。结果表明，分子量较小、芳香性较高的萘沥青组分被优先萃取出来；经过5次连续萃取后，萘聚合反应混合物中70%的萘沥青被萃出，仅需对少量夹带的氯铝酸离子液体予以碱洗及水洗等处理，即可使萘沥青的灰分值降低至0.0016%，且萃余相中的氯铝酸离子液体可重复使用。与传统碱液处理法相比，采用该方法所制备的萘沥青具有分子量较小且分布较集中、软化点较低的特点，以其为前体，可制备出各向异性组分含量高达99%的优质中间相沥青。

关键词: 萘沥青, 离子液体, 溶液萃取, 分离, 中间相沥青