Separation Of Benzene From N-Heptane By Extraction With （DMF+NH₄SCN）

In chemical, petrochemical and oil industry, separation of aromatic hydrocarbons fromalkanes is so important that it has always been active in research. Based on two aspects:1.aromatic hydrocarbons are the important raw materials for the rubber, synthetic fiber etc;2.the strict legal restrictions on the content of aromatics in gasoline. These aromaticcompounds including benzene, toluene, xylene and ethylbenzene; non-aromatic hydrocarbonis mainly C4-C10aliphatic hydrocarbon. Separation of benzene and n-heptane is an importanttypical case for the separation of aromatic/non aromatics.In this work, liquid-liquid equilibrium data for the system {n-Heptane+Benzene+（DMF+NH₄SCN）} were determined experimentally at T=（298.15or303.15） K andatmospheric pressure. According to the experimental data, the content of n-heptane in theextraction phase decreases with increasing NH₄SCN concentration in the solvent. But thecontent of benzene in the extraction phase increases with increasing benzene content in rawmaterial. And the triangle phase diagrams were drawed, from which it can be concluded thatdouble phase area enlarged with the increase of salt content and high salt content is helpful forphase-splitting.The consistency and reliability of the experimental LLE data was ascertained byapplying the Othmer-Tobias and Hand correlation. The experimental results were correlatedwith NRTL and UNIQUAC activity coefficient model. The root-mean-square deviation（RMSD） shows that, the NRTL model gives better results than UNIQUAC model.At last, the extraction process with （DMF+NH₄SCN） as solvent is simulated by AspenPlus V7.2and the results show that benzene recovery rate increased with increasing platenumber or with increasing solvent ratio or with increasing content of benzene in raw material.