Study On The Purification Process Of Fluorene And Acenaphthene In Coal Tar

Coal tar contains a large number of precious aromatic resources. The contents of fluorene and acenaphthene are very high of about 2% in coal tar. Fluorene and acenaphthene are the raw materials of many products like medicine, dyes, detergents and other industrial products. Also they have many kinds of derivatives which are widely used. The demand of fluorene and acenaphthene is growing constantly. How to separated fluorene and acenaphthene from coal tar effectively attracts more attention. In this paper, separation research about fluorene and acenaphthene from coal tar is carried on, including the separation process, crystallization thermodynamics and crystallization kinetics.The separation effects of fluorene in different solvents were investigated and then the influence of solvent quantity and purification steps was studied. According to the above conclusions, we draw a new method:Firstly, crude fluorine was washed by 200 # solvent oil. Then the mixture was crystalized after heating to completely melt at a solvent ratio of 1:0.8.At least, the purity of fluorene >95 % and yield of fluorene >80 %.This method has very high reference value for industrial production.At the same time, we measured the solubility curve of fluorene in the solvent of 200# solvent oil and fitted the Apelblat model and ?h model on the solubility curves. The metastable zone width of fluorene in the solvent of 200# solvent oil was calculated. We also measured the size of fluorene crystal and the settling velocity.Melt crystallization process is such a green process so that it has a very broad application prospects. As the final temperature of crystallization, the final temperature of sweating and the heating rate directly affect on the purity and yield of the acenaphthene melt crystallization process, the experimental conditions are selected in this paper. The optimal experimental conditions are obtained as follows:the terminal crystallization temperature is 40 °C; the final sweating temperature is 86 °C; the heating rate is 0.05 °C /min. At these experimental conditions, the yield of acenaphthene can reach 88.6% and the purity of acenaphthene can reach 99%.The crystallization kinetics of acenaphthene was studied by Differential Scanning Calorimetry(DSC). The crystallization kinetics of the Avrami model, Ozawa model and Kissinger model were calculated. Finally, the kinetics equation of each model was obtained and it can guide the industrial production.