CN110683937A - Method for separating benzene-n-propanol by using trioctylmethylammonium acetate as extractant - Google Patents
Method for separating benzene-n-propanol by using trioctylmethylammonium acetate as extractant Download PDFInfo
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- CN110683937A CN110683937A CN201910825670.XA CN201910825670A CN110683937A CN 110683937 A CN110683937 A CN 110683937A CN 201910825670 A CN201910825670 A CN 201910825670A CN 110683937 A CN110683937 A CN 110683937A
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- C07C29/76—Separation; Purification; Use of additives, e.g. for stabilisation by physical treatment
- C07C29/80—Separation; Purification; Use of additives, e.g. for stabilisation by physical treatment by distillation
- C07C29/84—Separation; Purification; Use of additives, e.g. for stabilisation by physical treatment by distillation by extractive distillation
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- C07C7/05—Purification; Separation; Use of additives by distillation with the aid of auxiliary compounds
- C07C7/08—Purification; Separation; Use of additives by distillation with the aid of auxiliary compounds by extractive distillation
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Abstract
A method for separating benzene-n-propanol by using trioctylmethylammonium acetate as an extracting agent relates to a method for separating benzene-n-propanol, and the method uses ionic liquid (trioctylmethylammonium acetate) as the extracting agent, and adopts a device comprising an extraction rectifying tower (tower 1) and an extracting agent recovery tower (tower 2). The tower 1 is a normal pressure rectifying tower, the top of the tower is provided with an extractant inlet and a condensation reflux device, raw materials enter from the middle part of the tower, benzene with the purity higher than 99.5wt% is produced from a material outlet of the tower 1, and a mixture of the n-propanol and the extractant flows out of the bottom of the tower 1 and enters from the top of the tower 2. The tower 2 is a vacuum rectification tower, n-propanol with the purity of 99.5wt% is produced from the top of the tower 2, and the extracting agent is produced from the bottom of the tower 2 and flows back to the tower 1 for reuse. The method has the advantages of convenient operation, easy control, realization of the recycling of the solvent, reduction of energy consumption, cost reduction, better separation effect, good economy and contribution to environmental protection.
Description
Technical Field
The invention relates to a method for separating benzene-n-propanol, in particular to a method for separating benzene-n-propanol by using trioctylmethylammonium acetate as an extracting agent.
Background
Benzene and n-propanol are important chemical basic raw materials, and can generate an azeotrope in the production and use processes of benzene and n-propanol, and the azeotrope can not be separated by using a common method, and extractive distillation is a common method for industrially separating the azeotrope. The extractive distillation is a special distillation method which adds a third component (called as an extractant or a solvent) into a raw material liquid to change the relative volatility of the original components so as to meet the separation requirement, and the extraction method requires that the boiling point of the extractant is much higher than that of each component in the raw material liquid, does not form an azeotropic liquid with the components, and is easy to recover. The key technology of extraction and rectification is the selection of an extracting agent, and the traditional organic solvent has the defects of large using amount, high energy consumption, easy volatilization, air pollution and the like; the traditional salt extractant has the problems of low solubility, strong corrosivity, easy crystallization at low temperature, equipment corrosion and blockage caused by calcification and the like. As a novel extracting agent, the ionic liquid has the advantages of negligible vapor pressure, high chemical stability, high boiling point, wide liquid range, recyclability, strong designability and the like, and can make up for the defects of the traditional extracting agent.
Benzene is a less polar hydrocarbon material, most highly polar ionic liquids are insoluble in benzene, while nonpolar ionic liquids generally have a lower separation capacity. Therefore, the ionic liquid used in the separation process of the benzene-n-propanol mixture has high solubility in polar and non-polar systems and simultaneously has high selectivity to a system to be separated. Since it is difficult to find a suitable ionic liquid by a simple experimental method, a precise quantum chemical calculation is performed before the experiment, and the range of the experiment is narrowed as much as possible from the aspects of solubility and selectivity.
In addition to solubility and selectivity, physical properties such as viscosity, density and the like of the ionic liquid also influence the final separation result, so that a gas-liquid phase equilibrium experiment is firstly carried out after the ionic liquid to be selected is obtained, and a proper thermodynamic equation is used for fitting measured data to establish a mathematical model. And testing physical properties such as viscosity, density and the like. And substituting the obtained result into ASPEN process simulation software for calculation, and debugging through actual rectifying tower operation to obtain the optimal extracting agent and the optimal technological process.
Disclosure of Invention
The invention aims to provide a method for separating benzene-n-propanol by taking trioctyl methyl ammonium acetate as an extracting agent.
The purpose of the invention is realized by the following technical scheme:
a method for separating benzene-n-propanol by taking trioctylmethylammonium acetate as an extractant is characterized in that ionic liquid (trioctylmethylammonium acetate) is taken as the extractant, and an extractive distillation tower (tower 1) and an extractant recovery tower (tower 2) are adopted to continuously separate benzene-n-propanol;
the preparation method comprises the following preparation processes: taking trioctylmethylammonium acetate as an extractant, and recovering benzene and n-propanol by using an extractive distillation tower and an extractant recovery tower, wherein the extractant is recycled; the extractant is added from the second or third tower plate of the rectifying tower; the benzene-n-propanol mixture raw material enters from the middle part of the tower; the total number of tower plates and the feeding position are related to factors such as the total amount of raw materials, the composition, the dosage of an extracting agent and the like, the initial calculation is carried out through ASPEN software, and the correction is carried out through an actual rectification experiment; benzene products are obtained at the top of the tower, the n-propanol extractant mixed liquor produced at the bottom of the rectifying tower enters a solvent recovery tower from the top of the tower, and the ionic liquid has almost no volatility, so the number of tower plates of the recovery tower is less; in order to avoid the decomposition or carbonization of the extracting agent caused by the overhigh temperature at the bottom of the tower, the tower (2) adopts reduced pressure rectification with the pressure of 200 Pa; the n-propanol is produced from the top of the tower, the extractant is produced from the bottom of the tower, and finally the extractant produced from the bottom of the solvent recovery tower is recycled and mixed with a small amount of supplementary extractant and then returned to the extraction and rectification tower.
The method for separating benzene-n-propanol by using trioctyl methyl ammonium acetate as an extracting agent takes trioctyl methyl ammonium acetate ionic liquid with the purity higher than 99.0wt% as the extracting agent.
The method for separating the benzene-n-propanol by taking the trioctylmethylammonium acetate as the extractant comprises the steps of taking an extractive distillation tower as a normal-pressure continuous distillation tower, wherein the top of the tower is provided with an extractant inlet and a product benzene outlet, the middle part of the tower is provided with an inlet of a raw material to be separated, and the bottom of the tower is provided with a mixture product outlet of the extractant and the n-propanol.
The method for separating benzene-n-propanol by using trioctylmethylammonium acetate as an extracting agent comprises the steps of using a tower (2) as a decompression tower, connecting the top of the decompression tower with a tower (1), enabling a mixture of the extracting agent and n-propanol to enter from the top of the tower, and respectively arranging n-propanol and an extracting agent outlet at the top of the tower and the bottom of the tower.
The invention has the advantages and effects that:
the method has the advantages of convenient operation, easy control, realization of the recycling of the solvent, reduction of energy consumption, cost reduction, better separation effect, good economy and contribution to environmental protection.
Drawings
FIG. 1 is a flow chart of the present invention.
Detailed Description
The present invention will be described in detail with reference to examples.
The method takes trioctylmethylammonium acetate as an extractant, and uses an extraction and rectification tower and an extractant recovery tower to recover benzene and n-propanol, and the extractant can be recycled. Since the ionic liquid is hardly volatile, the extractant is fed from the second or third tray of the rectification column. In order to ensure that the benzene-n-propanol system has enough rectifying and extracting sections during separation, the benzene-n-propanol mixture raw material enters from the middle part of the tower. The total number of tower plates and feeding position are related to the factors of total amount of raw materials, composition, dosage of extracting agent and the like, and can be initially calculated by ASPEN software and corrected by an actual rectification experiment. Benzene products are obtained at the tower top, and the purity can reach 99.5 wt%. The mixed liquid of the n-propanol extractant produced at the bottom of the rectifying tower enters the solvent recovery tower from the top of the tower, and the number of tower plates of the recovery tower is small because the ionic liquid has almost no volatility. In order to avoid the decomposition or carbonization of the extractant caused by the overhigh temperature at the bottom of the tower, the tower 2 adopts reduced pressure rectification with the pressure of about 200 Pa. The n-propanol is produced from the top of the tower, the purity can reach 99.5wt%, the extractant is produced from the bottom of the tower, and the purity of the extractant can reach 99.0 wt%. And finally, the extractant produced at the bottom of the solvent recovery tower is recycled and mixed with a small amount of supplemented extractant and then returns to the extraction and rectification tower.
Example 1: the extractive distillation flow path is shown in figure 1. The extractive distillation tower 1 is provided with 20 theoretical plates, an extractant trioctylmethylammonium acetate enters from the 2 nd theoretical plate, the flow rate is 10kg/h, and a mixture of benzene and n-propanol enters from the 11 th theoretical plate, wherein the composition of the mixture is 85.0wt% of benzene, 15.0wt% of n-propanol, and the flow rate is 100 kg/h; the extractive distillation tower 1 is operated under normal pressure, the reflux ratio is 2, the tower top can obtain 99.5wt% of benzene, and the tower bottom discharge is trioctylmethylammonium acetate-n-propanol mixed solution with the benzene content lower than 0.01 wt%; the bottom effluent of the tower enters a solvent recovery tower (tower 2) to recover the extracting agent, the pressure of the recovery tower is 220Pa, the theoretical plate of the tower 2 is 5 blocks, 99.5wt% of n-propanol is obtained at the top, and 99.0wt% of trioctyl methyl ammonium acetate is obtained at the bottom and can be recycled.
Example 2: the extractive distillation flow path is shown in figure 1. The extractive distillation tower 1 is provided with 25 theoretical plates, an extractant trioctylmethylammonium acetate enters from the 2 nd theoretical plate, the flow rate is 20kg/h, and a mixture of benzene and n-propanol enters from the 13 th theoretical plate, wherein the composition of the mixture is 75.0wt% of benzene, 25.0wt% of n-propanol, and the flow rate is 120 kg/h; the extractive distillation tower 1 is operated under normal pressure, the reflux ratio is 2.5, the tower top can obtain 99.5wt% of benzene, and the tower bottom discharge is trioctylmethylammonium acetate-n-propanol mixed solution with the benzene content lower than 0.01 wt%; the bottom effluent of the tower enters a solvent recovery tower (tower 2) to recover the extracting agent, the pressure of the recovery tower is 200Pa, the theoretical plates of the tower 2 are 6 blocks, 99.5wt% of n-propanol is obtained at the top, and 99.0wt% of trioctyl methyl ammonium acetate is obtained at the bottom and can be recycled.
Example 3: the extractive distillation flow path is shown in figure 1. The extractive distillation tower 1 is provided with 27 theoretical plates, an extractant trioctylmethylammonium acetate enters from the 2 nd theoretical plate, the flow rate is 25kg/h, and a mixture of benzene and n-propanol enters from the 13 th theoretical plate, wherein the composition of the mixture is 70.0wt% of benzene, 30.0wt% of n-propanol, and the flow rate is 200 kg/h; the extractive distillation tower 1 is operated under normal pressure, the reflux ratio is 2, the tower top can obtain 99.5wt% of benzene, and the tower bottom discharge is trioctylmethylammonium acetate-n-propanol mixed solution with the benzene content lower than 0.01 wt%; the bottom effluent of the tower enters a solvent recovery tower (tower 2) to recover the extracting agent, the pressure of the recovery tower is 250Pa, the theoretical plate of the tower 2 is 5 blocks, 99.5wt% of n-propanol is obtained at the top, and 99.0wt% of trioctyl methyl ammonium acetate is obtained at the bottom and can be recycled.
Claims (4)
1. The method for separating benzene-n-propanol by using trioctylmethylammonium acetate as an extractant is characterized in that ionic liquid (trioctylmethylammonium acetate) is used as the extractant, and an extraction rectification tower (tower 1) and an extractant recovery tower (tower 2) are adopted to continuously separate benzene-n-propanol;
the preparation method comprises the following preparation processes: taking trioctylmethylammonium acetate as an extractant, and recovering benzene and n-propanol by using an extractive distillation tower and an extractant recovery tower, wherein the extractant is recycled; the extractant is added from the second or third tower plate of the rectifying tower; the benzene-n-propanol mixture raw material enters from the middle part of the tower; the total number of tower plates and the feeding position are related to factors such as the total amount of raw materials, the composition, the dosage of an extracting agent and the like, the initial calculation is carried out through ASPEN software, and the correction is carried out through an actual rectification experiment; benzene products are obtained at the top of the tower, the n-propanol extractant mixed liquor produced at the bottom of the rectifying tower enters a solvent recovery tower from the top of the tower, and the ionic liquid has almost no volatility, so the number of tower plates of the recovery tower is less; in order to avoid the decomposition or carbonization of the extracting agent caused by the overhigh temperature at the bottom of the tower, the tower 2 adopts reduced pressure rectification with the pressure of 200 Pa; the n-propanol is produced from the top of the tower, the extractant is produced from the bottom of the tower, and finally the extractant produced from the bottom of the solvent recovery tower is recycled and mixed with a small amount of supplementary extractant and then returned to the extraction and rectification tower.
2. The method for separating benzene-n-propanol by using trioctylmethylammonium acetate as an extractant according to claim 1, wherein the trioctylmethylammonium acetate ionic liquid with purity higher than 99.0wt% is used as the extractant.
3. The method for separating benzene-n-propanol by using trioctylmethylammonium acetate as an extractant according to claim 1, wherein the extractive distillation column is an atmospheric continuous distillation column, the top of the column is provided with an extractant inlet and a product benzene outlet, the middle of the column is provided with an inlet for raw materials to be separated, and the bottom of the column is provided with a product mixture of the extractant and the n-propanol outlet.
4. The method for separating benzene from n-propanol by using trioctylmethylammonium acetate as an extractant according to claim 1, wherein the column (2) is a vacuum column, the top of which is connected to the column (1), the extractant and n-propanol mixture enters from the top of the column, and the top and bottom of the column are respectively provided with n-propanol and the extractant outlets.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN112778087A (en) * | 2021-01-14 | 2021-05-11 | 山东科技大学 | Method for separating methanol-toluene azeotrope through continuous extractive distillation |
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| CN104628522A (en) * | 2015-01-12 | 2015-05-20 | 济南大学 | Intermittent extractive distillation process for ethanol-methylbenzene azeotropic mixture |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN104628522A (en) * | 2015-01-12 | 2015-05-20 | 济南大学 | Intermittent extractive distillation process for ethanol-methylbenzene azeotropic mixture |
Non-Patent Citations (2)
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| WENXIU LI等: "Measurement and correlation of the vapor-liquid equilibrium of cyclohexane+ ethanol containing ILs and the thermophysical properties of these ILs at 101.3 kPa", 《J. CHEM. THERMODYNAMICS》 * |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112778087A (en) * | 2021-01-14 | 2021-05-11 | 山东科技大学 | Method for separating methanol-toluene azeotrope through continuous extractive distillation |
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