Study On Refining Process Of Fluorene And

Our country has rich coal tar resources and large coal tar processing enterprises suchasBaoshan Iron&Steel, JFE Zhenxing Shandong Chemical and Hongte Shanxi Chemical.Wash oilis the230-300℃distillates of coal tar. It contains some chemicals such as quinoline, naphthalene,acenaphthene, dibenzofuran and fluorene, which are widely applied in fine chemical materialslike high-performance materials, pharmaceutical intermediates, engineering plastics because oftheir special chemical structures. There are few domestic factories that develop wash oil products,and the product types they have developed and utilized are also few. It should be pretreated byacid-base neutralization in the wash oil processing. And then，the distillates are separated byobtaining the narrow fractions of specific temperature period. Due to the near boiling point ofsome components in wash oil, more layer numbers of plates are needed in rectification but thedistillates still can not be totally separated. The fluorene, dibenzofuran, acenaphthene,naphthalene, quinoline, biphenyl in wash oil can be enriched via rectification firstly, and thenrefined via some solvents.Gas chromatography is currently the main method to detect the products of wash oil.According to the composition features of the raw materials and based on the current conditions ofthe laboratory, the present project studies simultaneous detection of fluorene, dibenzofuran andacenaphthene by three wavelength spectrophotometry. The research shows that in a certainconcentration range, the absorbance of fluorene, dibenzofuran and acenaphthene obeys theLambert-Beer’s Law and has good additive property. It can measure fluorene, dibenzofuran andacenaphthene at the same time via the three wavelength spectrophotometry. It is appropriate toselect the reference wavelength of227nm,261nm and281nm respectively according to theultraviolet absorption spectra. Based on the equations of the three wavelength spectrophotometry,the MATLAB software is used to establish the equations for solving the three wavelengthspectrophotometry. The recovery experiments are carried out to verify the feasibility of thismethod. The results show that the relative error can be controlled between0.33%and2.5%, withrecovery rate over97.5%. This method is so rapid, simple, low cost and high accuracy that it canmeet the requirements of the analysis of multicomponent samples.Fluorene and dibenzofuran are the high contents separated by rectification. There will behigher requirements to the plate and larger energy loss if the rectification continues. Thus thesolvent washing and recrystallization is utilized to purify fluorene and dibenzofuran. Accordingto the principle of similar solubility parameters, it is not necessary to do experiments to predictthe solubility of the solvent selected to study the solvent washing. The Materials studio software is employed to make the molecular dynamics simulation calculation for the target compounds andto select the compounds with similar solubility parameters. According to the theoretical values ofthe solubility parameters and the nature of the solvents, anhydrous ethanol, propanol, n-butylalcohol, dimethyl benzene and the solvent E are selected in this study.The comparative study of the washing process of the above five kinds of solvents shows thatthe purity of fluorene is up from70.09%to83.63%with the recovery rate of96.65%under thefollowing conditions. The mass ratio of fluorene and the solvent E is1:1, washed one time in30℃water bath with magnetic stirring. The purity and recovery rate are higher than those of theother four solvents in this condition. And the orthogonal experiments are carried out to considerthe different mass ratio of the solvent E to fluorene, washing temperature, washing time andwashing times. The conclusions are that the purity of fluorene increases, but the yield decreaseswith the increasing of mass ratio of the solvent E to fluorene. However, the purity of fluorenebegins to decline when the ratio of the solvent E to fluorene is more than1. The purity of fluorenerises with the increasing of washing temperature, but the yield significantly decreases. Thesuitable washing temperature is30℃in the solvent E. The mixing time in solvent E has littleinfluence on the purifying effect of fluorene and washing time of30minutes can achieve itsbalance. The double solvent washing is found to be better than the single solvent washing. Thepurity is over93%and the yield is over90%after washing. Through the next recrystallization,the purity can increase to99.02%and the yield is90.27%.The purity of dibenzofuran is99.10%and the yield is85.55%merely through solventwashing under the following conditions: The stirring speed is200r/min. The mass ratioof thesolvent to dibenzofuran is1:1. The washing time is20mins. The washing temperature is20℃and washing times twice.The solvent E has the advantages of high purity and high yield on the separation andpurifying of fluorene and dibenzofuran. It is a new process to separate and purify fluorene anddibenzofuran via the solvent E washing and the next recrystallization, which will play animportant role in the development and utilization of fluorene and dibenzofuran.