关键词: 熔融结晶, 提纯, 结晶器, 萘, 对二甲苯, 均四甲苯

Abstract: Melt crystallization is of great importance in the purification of homologues, azeotropes and heat-sensitive substances. It has been widely utilized in numerous chemical industries because of its high selectivity for pure products, low energy consumption, no gaseous phase, no recovery of solvents and the convenience to industrialization. This work reviewed the development and application status of melt crystallization technology in the purification of high value-added products, based on the different crystallization processes in recent years. Examples were compared to emphasize the advantages as well as disadvantages. There were a large number of high value-added products in poor quality heavy aromatics such as ethylene tar, reforming aromatics and coal tar, which contained great number of naphthalene, xylene, durene, anthracene, phenanthrene, carbazole, acenaphthylene and so on. The separation and purification of these products were extremely meaningful both economically and technologically. Melt crystallization played a promising role in the purification of these high value-added products. Considering the advantages of engineering application, the hybrid of distillation and melt crystallization, the ultrasound-assisted crystallization and other coupling processes had been designed to meet the requirements in various industrial areas, which explored quite promising application areas of melt crystallization. Batch process played a really important role in the industrial scale process, which facing the problems of large labor cost and unstable product quality. Although many efforts had been made to improve the continuous crystallization, it was still not as universal as batch crystallization due to the existence of the drawbacks, such as blockage and encrustation. Novel research with suitable interpretation into the mechanism were potential solutions for the shortcomings of the current process. Finally, studies on mass and heat transfer, enhanced controller of crystals and crystallization systems for multicomponent promised a bright future for the design of novel crystallizers, models and some assistive technologies.

Key words: melt crystallization, purification, crystallizer, naphthalene, p-xylene, durene