Study On The Separation Of Hexanol-Heutanol-Decane-Undecane Mixture

Fischer-Tropsch synthesis product contains dozens of compounds which is mainly composed of linear paraffin and primary alcohols.Primary alcohols especially with over six carbon numbers are valuable chemical material.Considering azeotropes between the alcohols and alkanes,extraction becomes one of the simple and economical way to get alcohols from the mixture.The mixture consisted of hexanol,heptanol,decane,undecane was selected in this paper.Based on extraction and distillation,the separation scheme of 1500t/y heptanol-hexanol-decane-undecane mixture was designed and optimized by experiment and simulation.Firstly,the experimental LLE data of the quaternary systems ethanol + hexanol +decane + water,ethanol + hexanol + undecane + water,ethanol + heptanol + decane +water,ethanol + heptanol + undecane + water were performed at 298.15K under atmospheric pressure.The UNIQUAC model was used to regress the quaternary systems and acquire the binary interaction parameter,which was used to predict the LLE data of six-component system.The predicted LLE data was compared with the experimental data and the results showed they were in good agreement,which indicated that the binary interaction parameters acquired from the quaternary systems could predict LLE data of the six-component system.The distribution coefficient and the selectivity showed that 65%ethanol aqueous solution was suitable for separating hexanol and heptanol from hexanol-heptanol-decane-undecane mixture.Secondly,the experimental LLE dataof the seven-component systems ethanol+hexanol+heptanol+ decane+undecane+ water+ hexadecane were performedat 298.15K under atmospheric pressure.The UNIQUAC model was used to regress the seven-component system and acquire the binary interaction parameter.Then the acquired binary interaction parameter and the default binary interaction parameter in Aspen Plus of UNIQUAC model was used to predict LLE data of the seven-component systemand compare with the experimental data.The results showed the LLE data predicted by acquired binary interaction parameter was in better agreement with the experiment than the default parameter in Aspen Plus.Finally,aprocess design of separating 1500ton/year heptanol-hexanol-decane-undecane mixture was presentedin this paper through the simulation and optimization of Aspen Plus.Heptanol-hexanol-decane-undecane mixture was extracted by 65%ethanol aqueous solution and the alcohol-phase was anti-extracted by hexadecane.After a series of distillation treatments,99.7%heptanol-hexanol product and 99.9%decane-undecane product were obtained with the recovery rate higher than 99%while the extractant and anti-extractant were recycled.At last,anti-extraction experiment was conducted to prove the accuracy of the anti-extraction simulation.