Studies On Preparation Of Pure Anthracene From Crude Anthracene By Extractive Drowning-out Crystallization

As a most important and bulk product of the coal tar processing industry, anthracene is an indispensable and vital basic organic chemical raw material. Refined anthracene is mainly separated and purified by solvent-washing and crystallization from crude anthracene in China. According to the problems in the refine anthracenemanufacture, such as high cost, low purity, and so on, a novel extractive drowning-outcrystallization process was carried out to preparation anthracene from crudeanthracene. As a new emerging of coupling separation technology, the extractivedrowning-out crystallization will play an important role in the pharmaceutical industry,chemical industry, environmental protection and other fields.The refine anthracene with a high purity (≥98%) was produced bysolvent-washing, azeotropic distillation and liquid membrane crystallization underlaboratory conditions. The method for the determination of the anthracene content inDMF by ultraviolet spectrophotometry has been set up, which has been validated bychemical titration. The results shows that the two methods are highly consistent.The solubility of anthracene in303.45~353.55K in different solvents, i.e. DMF,benzene, toluene, benzene-DMF, toluene-DMF and water-DMF, was determined by the equilibrium method. The solubility data was correlated by empirical equation, idealsolution equation and λ-h equation. The above results can be very important phase equilibrium data for design and development of the novel Extractive Drowning-out Crystallization to refine anthracene from crude anthracene.During crystallization process, three main factors including the amount of water,the amount of toluene, and temperature, on the purity of anthracene were studied bysingle factor analysis method. The results shaow that in the test range, the quantity ofwater and toluene have great infuence on the purity of anthracene, while temperaturehas little effect. Based on the single factor experiments，the purity of the anthracenewas investigated to optimize the separation and purification process by Second orderorthogonal rotative regression design. The regression equation and response surfacefigure from three factor interaction were presented and the obtained optimizedconditions were as follows: the amount of water/DMF=5, DMF/toluene=3, thetemperature is61.39℃．Under the optimized operation conditions．The purity ofanthracene can reach95.21%, the yield is greater than70%.