Study On Extraction And Separation Of Distillate Oil From Waste Coal Tar Hydrogenation

In this study,the waste catalyst for hydrogenation of coal tar produced by an enterprise’s refining was used as the raw material,and the distillate oil in the spent catalyst was extracted by the method of ultrasonic assisted deoiling.Based on literature research,the deoiling solvent was screened.Taking the deoiling rate as an evaluation index,combined with the component analysis of the distillate oil obtained by deoiling,the deoiling ability of twelve pure solvents on the spent catalyst was investigated.The results show that when isobutyl acetate and isoamyl acetate are used as deoiling solvents,the deoiling rate is relatively high,and the obtained distillate oil basically guarantees the integrity of the sample analysis.At the same time,considering factors such as the toxicity of the solvent and the price,isobutyl acetate is selected as the deoiling solvent.Using isobutyl acetate as the deoiling solvent,the process conditions of ultrasonic deoiling were studied through single factor experiments,and the effects of ultrasonic temperature,ultrasonic time and liquid-solid ratio on the deoiling rate were discussed.Appropriate process conditions were obtained:the ultrasonic temperature was 35℃,the ultrasonic time was 80 min,and the liquid-solid ratio was 15:1.Under these conditions,the deoiling rate of the spent catalyst was higher.The method of distillation was used to regenerate isobutyl acetate and its regeneration performance was investigated.The results showed that the deoiling solvent isobutyl acetate was regenerated and repeatedly used seven times,the oil deoiling rate is reduced by less than 5%,and it has good regeneration performance.Under suitable ultrasonic-assisted deoiling process conditions,the multi-stage cross-flow extraction of distillate oil from the waste coal tar hydrogenation catalyst was carried out,and the effect of extraction stages on the deoiling rate was investigated.The results showed that the appropriate number of cross-flow extraction stages was five stages.On this basis,five stages of false counter-current extraction were carried out,the extractant was fully utilized,and the extraction rate of distillate oil reached 65.34%.Based on the single-factor experimental results,the ultrasonic-assisted deoiling process conditions were further optimized by the response surface method,and a quadratic polynomial regression equation about the deoiling rate was established.The optimal process conditions predicted by the model:ultrasonic temperature A is 30.28℃,ultrasonic time B is 107.14 min,and solvent volume C is 87.02 mL(5 g of spent catalyst).Under this condition,the oil removal rate Y predicted by the model is 43.53%.A verification experiment was conducted under this condition.The repeatability of the oil removal rate of the three parallel experiments is good,with an average value of 43.47%,which is consistent with the predicted value of the model.