Pyridine-Based Ionic Liquids In The Liquid-Liquid Extraction Of-P-xylene From N-octane

Separation of aromatic compounds from its mixture with aliphatics is of great importance in petrochemical industries. Octane and p-xylene are two important commodity chemicals existing in petrol. Owing to their close boiling points, which forms them as azeotrope, makes it much more difficult in separating p-xylene with octane by traditional separation techniques. In this work, three different pyridine ionic liquids(ILs),[Epy][EtSO4](1-ethylpyridinium ethyl sul fate),[Empy][EtSO4](1-Ethyl-3-Methypyridinium ethylsulfate) and [Mpy][MeSO4](1-ethylpy-ridinium methyl sul fate) are selected as the solvent in the extracion of p-xylene from n-octane.At first,three kind of ILs are sythensised. NMR and Karl Fischer Moisture Titrator are used to analysis the ILs. Secondly, The liquid-liquid equilibrium (LLE) data for the ternary mixtures of{n-octane (1)+p-xylene (2)+ILs(3)} were experimentally determined at T=(298.15and313.15) K and atmospheric pressure. The consistency of tie-line data was ascertained by applying the Othmer-Tobias equations. From the experiment data we can found that:(1) Both temperatures share the same trend of the distribution ratio, within a certain range fluctuations.(2)The selectivities at both temperatures are highly similar and reduced with increasing mole fraction of p-xylene.(3) Separation efficiency can be generally ranked as [Empy][EtSO4]>[Epy][EtSO4]>[Mpy][MeSO4]. The results show that the temperature dependence of extraction selectivity for ILs is negligible.[Empy][EtSO4] can be confirmed as a potential alternative solvent for the separation of p-xylene from octane in three pyridine ILs. At last, The NRTL(non-random two liquid) model was used to correlate and predict the LLE data of system, the modes parameters were fitted. Besides this, the extraction simulation was made by Aspen Plus at T=298.15K and atmospheric pressure for [Empy][EtSO4], The results show that [Empy][EtSO4] can be confirmed as a potential alternative solvent for the separation of p-xylene from octane.