Method for extracting p-xylene in n-octane by using [Bmim][FeCl4]

Abstract

The invention relates to a method for extracting a p-xylene mixture in n-octane by using an ionic liquid [Bmim][FeCl4]. The method comprises the following steps: (1) preparation of [Bmim][FeCl4]; (2) separation of n-octane and p-xylene mixture: S1. preparing a mixed solution of n-octane and p-xylene in different mole ratios in a balance kettle; and S2. adding the ionic liquid which is equal to the total mass sum of the n-octane and p-xylene, stirring at uniform speed, and standing at a certain constant temperature for stratification. The quantitative analysis on the stratified liquid phases by gas chromatography detects that the ionic liquid has the advantages of favorable absorption effect on p-xylene, high selectivity and obvious separating effect. The method is simple and easy to implement, has the advantage of wide raw material application range, can be performed at normal temperature, and lowers the energy consumption.

Description

technical field [0001] The invention relates to the field of liquid-liquid extraction, in particular to a method utilizing ionic liquid [Bmim][FeCl 4 ] Extraction method for separation of mixtures of n-octane and p-xylene. Background technique [0002] Paraxylene (PX) is a very important chemical raw material, and there is a great demand for it in my country. It is mainly obtained from mixed xylenes catalyzed from naphtha through adsorption separation and crystallization separation. The separation of aromatic and aliphatic hydrocarbons, especially n-octane and p-xylene, is of great significance in the petrochemical industry. However, n-octane and p-xylene have very similar boiling points and tend to form azeotropes, so it is difficult to separate them. The most common separation method is extractive distillation. Extraction and rectification using traditional solvents such as sulfolane, glycerol, dimethylformamide, N-formylmorpholine, etc. There are some problems in term...

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Problems solved by technology

[0010] In the above synthesis method, toxic chemical substances such as toluene, cyclohexane, ethyl acetate, acetone, CH 2 Cl 2 etc., will cause harm to the body of the experimenter; in addition, the synthesis method has many steps, the synthesis is complicated, and there are too many uncontrollable factors, which makes the experimental results unstable

[0011] Using [bmim]PF 6 During the separation of ionic liquids, it is necessary to adjust the pH value and centrifuge many times, which is cumbersome.

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