Application of ionic liquid used as solvent in benzene and cyclohexane extraction, rectification and separation

An ionic liquid solvent and ionic liquid technology, which is applied in distillation purification/separation, organic chemistry, bulk chemical production, etc., can solve the problems of complex separation process, equipment investment and high energy consumption of separation, and achieve high chemical stability and wide Effect of liquid temperature range, process and operational simplification

Inactive Publication Date: 2008-09-17
CHINA UNIV OF PETROLEUM (BEIJING)
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0014] The currently commonly used organic solvents for extractive distillation have limitations in the selectivity, volatility, stability and other physical properties of raw materials, which makes the existing e...

Method used

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  • Application of ionic liquid used as solvent in benzene and cyclohexane extraction, rectification and separation
  • Application of ionic liquid used as solvent in benzene and cyclohexane extraction, rectification and separation
  • Application of ionic liquid used as solvent in benzene and cyclohexane extraction, rectification and separation

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0043] Utilize ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate as extractant to join in the mixture of benzene and cyclohexane (benzene molar content is 10%~90%), its addition has great influence on the relative volatility of the system The impact can be seen in Table 3.

[0044] Table 3: Effect of adding ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate on relative volatility

[0045]

[0046] According to the experiment, the relative volatility of cyclohexane / benzene is improved to a certain extent when the molar content of ionic liquid is 10%~30%. The effect of the vapor-liquid equilibrium curve is more significant, see the attached image 3 , in the whole concentration range, the vapor pressure of cyclohexane is higher than that of benzene, so that the volatility of cyclohexane is greater than that of benzene. In the concentration range of benzene from 10% to 90%, cyclohexane The relative volatility of p-benzene exceeds 1, realizing the use of ...

Embodiment 2

[0048] Utilize ionic liquid 1-butyl-3-methylimidazolium bromide as extractant to add in the mixture of benzene and cyclohexane (benzene molar content is 10%~90%), the influence of its adding amount on the relative volatility of the system See Table 4.

[0049] The impact on relative volatility after adding ionic liquid 1-butyl-3-methylimidazolium bromide salt in table 4

[0050]

[0051]

[0052] As can be seen from the above table, after adding 1-butyl-3-methylimidazolium bromide with 20% molar concentration of ionic liquid, the molar content of cyclohexane is within the range of 10% to 90%. The relative volatility has been improved to a certain extent. Except that the relative volatility is 0.99 when the cyclohexane content is 0.7, the relative volatility is higher than 1 at other concentrations. It can be seen that this kind of ionic liquid can also be added to benzene and cyclohexane as an extraction agent. Extractive distillation and separation in hexane.

Embodiment 3

[0054] Utilize ionic liquid 1-butyl-3-methylimidazolium bromide as extractant to add in the mixture of benzene and cyclohexane (benzene molar content is 10%~90%), the influence of its adding amount on the relative volatility of the system See Table 5.

[0055] The impact on relative volatility after adding ionic liquid 1-butyl-3-methylimidazolium bromide in table 5

[0056]

[0057]

[0058] As can be seen from the above table, after adding ionic liquid 1-butyl-3-methylimidazolium bromide, the relative volatility of cyclohexane / benzene is improved in various degrees, except that the initial molar content of benzene in the raw material is When the relative volatility is less than 1 at 0.8, the other molar contents are all greater than 1, which provides a basis for the separation of benzene and cyclohexane by extractive distillation.

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Abstract

The invention discloses the application of ionic liquid which is used as a solvent for separating benzene and cyclohexane by extractive distillation, and relates to the application that the ionic liquid is used as the solvent during the process of separating the benzene and the cyclohexane by extractive distillation. Cationic in the ionic liquid is imidazole cationic, anion in the ionic liquid isfluorophoshoric acid anion or halide anion, and ionic liquid solvent is one ionic liquid or two or more than two compounded ionic liquid; the water content of the ionic liquid is 0 percent to 20 percent, and the addition amount ranges in the molar concentration from 5 percent to 90 percent; light-component cyclohexane with low boiling point is obtained at the top of a rectification column and themixture of the ionic liquid and the benzene is obtained in a column reactor during the separating process; the mixture passes through an evaporator or is performed through steam stripping separation.The extractive distillation technology of the ionic liquid solvent increases the separation precision, and obviously simplifies process flow agents, reduces equipment investment and lowers the separation energy consumption at the same time, thereby getting very remarkable economic benefits.

Description

technical field [0001] The invention relates to the application of an ionic liquid, in particular to the application of an ionic liquid as a solvent in the process of separating benzene and cyclohexane by extraction and rectification. Background technique [0002] In the petroleum processing industry, benzene and cyclohexane have similar boiling points (benzene is 80.1°C and cyclohexane is 80.74°C), and their relative volatility is close to 1, so it is difficult to separate them by ordinary rectification. The number of theoretical plates is large, or a large reflux ratio is required, and the operating cost is much higher than the separation of the general system. [0003] Table 1 lists the approximate number of theoretical plates required to separate systems with different relative volatilities by ordinary distillation under certain separation requirements. It can be seen that the greater the relative volatility of the system, the easier it is to separate. If the relative v...

Claims

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Application Information

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IPC IPC(8): C07C7/08C07C13/18C07C15/04
CPCY02P20/54
Inventor 刘艳升胡玉峰曹睿刘拥军
Owner CHINA UNIV OF PETROLEUM (BEIJING)
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