Study On Separation Of Decanol-Undecanol-Tetradecane-Pentadecane Mixture

Higher alcohols have high economic value and are used as basic raw materials for the synthesis of fine chemicals.The production of higher alcohols by Fischer-Tropsch synthesis has been researched in recent years,the components of Fischer-Tropsch synthesis products are complex,n-alkanes and primary alcohols can form azeotropes,higher alcohols cannot be separated by ordinary distillation.In this paper,Aspen plus was used to design a 2500t/a process for separating the mixture of decanol+undecanol+tetradecane+pentadecane by experiment and simulation.Firstly,ethanol aqueous solution was chosen as extractant,the liquid-liquid equilibrium(LLE)data of the four quaternary systems ethanol+decanol tetradecane+water,ethanol+decanol+ pentadecane+water,ethanol+undecanol+ tetradecane+water and ethanol+ undecanol+pentadecane+ water and the six-component system ethanol+ decanol+undecanol+tetradecane+pentadecane+water were obtained at 293.15K,298.15K and 303.15K under atmospheric pressure.UNIQUAC model was used to regress the LLE data of the four quaternary systems to obtain the binary interaction parameters,which were used to predict the LLE data of the six-component system.The results showed that the predicted and experimental data were in great agreement,which meant that the binary interaction parameters regressed by the LLE data of the four quaternary systems could be used-to predict the LLE data of the six-component system and consequently could be used in extraction simulation and optimization by Aspen Plus.By analyzing the distribution coefficient and selectivity,it was found that 80 wt%ethanol aqueous solution was a superior extractant and 293.15K to 298.15K was the suitable temperature.Secondly,octadecane was chosen as back extractant,the LLE data of the seven-component system ethanol+decanol+undecanol+tetradecane+pentadecane+water+ octadecane were obtained at 303.15K,308.15K and 313.15K under atmospheric pressure,and the binary interaction parameters involved the component octadecane were obtained by data regression using UNIQUAC model.The regressed parameters and default parameters were used to predict the LLE data of the seven-component system,the results showed that the regressed parameters were more accurate,which meant that the regressed binary interaction parameters could be used in extraction simulation and optimization by Aspen Plus.Finally,a 2500t/a process of separating the mixture of decanol+undecanol+tetradecane+pentadecane was designed by Aspen plus with these regressed binary interaction parameters.The mixture of decanol+undecanol+tetradecane+ pentadecane was extracted by 80 wt%ethanol aqueous solution,and the extract phase was extracted by octadecane.On optimization,99.76 wt%tetradecane+pentadecane product and 99.80 wt%decanol+undecanol product were obtained.The extractant and back extractant were recycled.