Method for ultrasonic extraction and distillation separation of benzene-cyclohexane and benzene-n-heptane

A technology of extractive distillation and cyclohexane, applied in the direction of distillation purification/separation, etc., can solve the problems of spending a lot of energy, easy precipitation of salt components, etc., and achieve the effect of improving relative volatility, good separation effect, and improving separation effect.

Inactive Publication Date: 2010-06-02
HARBIN ENG UNIV
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  • Claims
  • Application Information

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Problems solved by technology

It is reported that extraction and rectification with salt addition can be successfully applied to the separation of polar substances, but the separation of non-polar substances is still in its infancy and the selection of salts is still in the experimental stage, and the problem of easy precipitation of salt components re

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  • Method for ultrasonic extraction and distillation separation of benzene-cyclohexane and benzene-n-heptane
  • Method for ultrasonic extraction and distillation separation of benzene-cyclohexane and benzene-n-heptane

Examples

Experimental program
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Example Embodiment

[0015] Embodiment 1: Separation of benzene-n-heptane near-boiling point system by ultrasonic extraction and distillation

[0016] Benzene and n-heptane mixture (n-heptane molar content is 6.74%) is mixed with a certain amount of furfural solvent (solvent ratio 0.5: 1~2: 1), placed in an ultrasonic field for 30min, (ultrasonic field condition is output frequency 22KHz, power is 240W). Pour the material into an extractive still for distillation. The operating pressure of the extractive distillation is normal pressure, the temperature of the kettle is constant at 90-120°C, and the distillate is a mixture of n-heptane and benzene. Samples were taken every 15 min for analysis. Distillation was carried out under the same conditions without the addition of an ultrasonic field, and samples were taken for analysis. The relative volatility results of the system with and without ultrasound are as follows: figure 1 shown.

[0017] Depend on figure 1 It can be seen that under the sam...

Example Embodiment

[0018] Embodiment 2: Ultrasonic extraction distillation to separate benzene-cyclohexane azeotrope

[0019] The mixture of benzene and cyclohexane close to the azeotrope composition (the molar content of benzene is 45% to 58%) is mixed with a certain amount of DMF solvent (solvent ratio 0.2), and the material is poured into the extractive distillation still for distillation. The extractive distillation operating pressure was normal pressure, the kettle temperature was 90-120°C, and an ultrasonic field was intermittently added every 10min (ultrasonic field conditions were: output frequency 22KHz, power 308W) for 10min. When the vapor and liquid temperatures are equal and constant at 80-85°C, take the distillate for detection and analysis by chromatography. Distillation was carried out under the same conditions without the addition of an ultrasonic field, and samples were taken for analysis. The relative volatility results of the system with and without ultrasound are as follows...

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Abstract

The invention provides a method in separating benzene from cyclohexane and from heptane by ultrasonic extractive distillation, comprising steps as ultrasonic processing and extractive distillation. The ultrasonic extractive distillation method adopts the conditions for the extractive distillation in that: under atmospheric pressure, a volume ratio between the raw material solution and solvent is between 0.2 and 2; constant temperature for the distilled materials is kept between 70 and 80 centigrade; the bottom temperature is constantly kept between 90 and 120 centigrade; the ultrasonic processing is characterized in that ultrasonic fields, with ultrasonic output frequencies from 20 to 24 KHz, powers from 200 to 308W and ultrasonic time from 10 to 40 minutes, are added at the pre-processingphase, or intermittently or continuously added in the process of extractive distillation. Aiming at the benzene and cyclohexane azeotropic system and the benzene and heptane systems with close boiling points, the ultrasonic techniques coupled with the extractive distillation is put forward to improve the separation efficiency of the extractive distillation through the acoustic cavitation of the ultrasonic wave.

Description

1. Technical field [0001] The invention relates to a novel combined separation technology, in particular to a coupling technology of ultrasonic and extractive distillation. 2. Background technology [0002] At present, the separation process is developing towards high-efficiency and fine separation. The research hotspots have a certain extreme color, focusing on the preparation of high-purity substances, the extraction of trace components, and the separation of species with relative volatility approaching 1. [0003] For the separation of the system with relative volatility approaching 1, such as removing the alkane impurities cyclohexane, n-heptane and methylcyclohexane in crude benzene (benzene and cyclohexane form an azeotrope, while for benzene-containing 93 The relative volatility of the mixture of benzene and n-heptane in % (molar mass fraction) is only 0.962), and extractive distillation technology is often used. The classic extractive distillation technology is to in...

Claims

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Application Information

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IPC IPC(8): C07C7/08C07C15/04C07C13/18C07C9/15
Inventor 董红星杨晓光姚春艳王晓宇
Owner HARBIN ENG UNIV
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