Study On Separating The Non-polarial System Of N-heptane And Benzene By Extractive Distillation With Salt

The benzene is a kind of important organic industrial chemicals, and widely apply to the trades , such as agriculture chemical , medicine , dyestuffs and organic synthesis industry ,etc. it has very high expectations for its purity and the great market demand, So we can make and fetch the benzene products suitable for market demand economically and have great social effects.The benzene stems from the coal industry and petroleum chemical industry mainly, it is different to some extent because the content of the coarse hydrocarbon, generally inthe ranges of 40%-90%, the others for aromatic hydrocarbon, including alkane and hydrocarbon,the sulphides,the nitrogen thing,etc. which is mainly alkane and hydrocarbon of cyclohexane,n-heptane and methy-cyclobexane,which is accounted for more than 90% of the total content of impurity.It is reported that the relative volatility is only 0.962 between benzene and n-heptane and relative volatility reduce too with reduction of impurity content, so it is difficult to separate at all alkane hydrocarbon in benzene general rectification method .It was widely discussed of getting rid of hydrocarbon and impurity of benzene for obtain high purity benzene by the academia.It was reported that the . complex solvent of NMP, or DMF regards as solvent rectification. But these two kinds of methods both have some shortcoming of solvent great consumption, the energy consumption , the efficiency low of the board, which make its application limited, then in the text we propose the solvent DMF with salt to extract rectification getting rid of hydrocarbon impurity from benzene.The extract rectify with salt is a kind of new-type special rectify method which incorporates extracting rectify and dissolving salt rectify into an organic whole and was caused the great attention by the academia. It is the extract solvent of dissolving salt in advance,while the exetract solvent is joining to the solution of waiting to separate The salt and solution every interaction of group is different,and that the solvent component of every group of relative volatility is caused changes,thus the goal of separating is achieved.Its advantage reflect on 1. the salt dissolved can improve the separate group to relative volatility and overcome the shortcoming of bad efficiency,great consumption etc.2.It is convenient of the liquid to retrieve circulation.The advantages is easy to realize on industry,it overcomes the shortcomings of the solid salt of retrieve and sent,etc.Promptly,it improves the solvent result and reduces solventratio,convenient to use.unique advantage and efficiency. So the extract rectify with salt is a kind separation technology of extraordinary application prospects.The extract rectification with salt is succeed in separating alcohol - water , ester - water ,etc.But there are few study reports about separating non-polarity system. At present the doctor Lei Zhigang by the solvent Div^ CAN added the salt extracts rectify to separate C4 group grade in Qinghua university. There are few reports about separating the non-polarity system. The solvent with DMF and KSCN separats benzene low n-heptane from benzene in the text. It explores a new kind separation method of the low n-heptane of the benzene,and widens the vision of the separation of the extract rectification.Through the balancing experiment of vapour liquid,we see about the type of the salt,density,temperature,solvent ratio,etc. Through the experiment of the extract rectify with salt,we investigate these factors affect the content of n-heptane in cauldron liquid.The results showed that when dropping the extraction agent continuously, V(extraction solvent):V(raw material) is 1.2, percent of quality of KSCN is 12%, the n-heptane whose percent of volume is 0.1 is separated from material liquid with extractive rectify with salt 95% of rc-heptane can obtained in the tower top ,The n-heptane in tower kettle can drop to 0.8%.On the basis of experiment,we go on the comments of DMF extract rectify with salt separating n-heptane-benzene of the no-polarity system in theory in this text.And on the basis of the balanced model of liquid phase of air,Pan XiaoMei of university of Tianjin putting forward,which apply to .the no-polarity things.