CN117776847A - Process method for separating ethylbenzene and styrene by extractive distillation - Google Patents
Process method for separating ethylbenzene and styrene by extractive distillation Download PDFInfo
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- CN117776847A CN117776847A CN202311818619.9A CN202311818619A CN117776847A CN 117776847 A CN117776847 A CN 117776847A CN 202311818619 A CN202311818619 A CN 202311818619A CN 117776847 A CN117776847 A CN 117776847A
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- Prior art keywords
- styrene
- ethylbenzene
- extractant
- rectifying tower
- extractive distillation
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- PPBRXRYQALVLMV-UHFFFAOYSA-N Styrene Chemical compound C=CC1=CC=CC=C1 PPBRXRYQALVLMV-UHFFFAOYSA-N 0.000 title claims abstract description 154
- YNQLUTRBYVCPMQ-UHFFFAOYSA-N Ethylbenzene Chemical compound CCC1=CC=CC=C1 YNQLUTRBYVCPMQ-UHFFFAOYSA-N 0.000 title claims abstract description 114
- 238000000034 method Methods 0.000 title claims abstract description 35
- 238000000895 extractive distillation Methods 0.000 title claims abstract description 31
- 238000011084 recovery Methods 0.000 claims abstract description 35
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 claims abstract description 31
- 238000000605 extraction Methods 0.000 claims abstract description 30
- 239000000203 mixture Substances 0.000 claims abstract description 27
- 239000002994 raw material Substances 0.000 claims abstract description 12
- 238000004821 distillation Methods 0.000 claims description 3
- 238000000926 separation method Methods 0.000 abstract description 8
- 229920000642 polymer Polymers 0.000 abstract description 6
- 238000010992 reflux Methods 0.000 description 7
- 238000006356 dehydrogenation reaction Methods 0.000 description 4
- 239000007788 liquid Substances 0.000 description 4
- UHOVQNZJYSORNB-UHFFFAOYSA-N Benzene Chemical compound C1=CC=CC=C1 UHOVQNZJYSORNB-UHFFFAOYSA-N 0.000 description 3
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 description 3
- 238000004064 recycling Methods 0.000 description 3
- 238000009835 boiling Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 239000000945 filler Substances 0.000 description 2
- 238000000746 purification Methods 0.000 description 2
- 238000012719 thermal polymerization Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000004566 building material Substances 0.000 description 1
- 239000013064 chemical raw material Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 229920001971 elastomer Polymers 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 229920003023 plastic Polymers 0.000 description 1
- 238000006116 polymerization reaction Methods 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 239000005060 rubber Substances 0.000 description 1
- 230000002194 synthesizing effect Effects 0.000 description 1
- 239000011269 tar Substances 0.000 description 1
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- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
The invention relates to a process method for separating ethylbenzene and styrene by extractive distillation, which comprises the steps of carrying out extractive distillation on a mixture of ethylbenzene and styrene to be separated by taking N-methyl pyrrolidone as an extractant, and feeding the extractant and the styrene into the bottom of an extractive distillation tower under the action of the extractant, so as to obtain ethylbenzene at the top of the extractive distillation tower; the mixture of the extractant and the styrene at the bottom of the extraction rectifying tower enters the recovery rectifying tower from a raw material feed inlet of the recovery rectifying tower, the styrene is obtained at the top of the recovery rectifying tower, and the extractant at the bottom of the recovery rectifying tower is recycled; the invention adopts N-methyl pyrrolidone as the extractant, not only increases the volatility difference of ethylbenzene and styrene and realizes the effective separation of ethylbenzene and styrene, but also the extractant can dissolve the polymer formed by styrene in the rectification process, thereby greatly reducing the occurrence of the problem that the polymer blocks a rectification tower.
Description
Technical Field
The invention belongs to the technical field of organic solvent separation, and particularly relates to a process method for separating ethylbenzene and styrene by extractive distillation.
Background
Styrene is an important organic chemical raw material, is mainly used for synthesizing plastics, rubber, resin and the like, is applied to various fields such as building materials, electronic products, automobile parts, medical equipment and the like, and has wide market demands. At present, more than 90% of styrene products are produced by ethylbenzene dehydrogenation. The technology process mainly comprises two parts of ethylbenzene dehydrogenation and styrene rectification purification, wherein ethylbenzene is firstly dehydrogenated in a reactor to generate styrene, and the formed dehydrogenation liquid contains a large amount of ethylbenzene, a small amount of benzene, toluene, tar and the like; and then separating the finished styrene product and the recyclable ethylbenzene from the dehydrogenation liquid by adopting a rectification method. However, styrene is a heat-sensitive material, and is easily polymerized at a higher temperature, and in order to reduce the occurrence of polymerization reaction, the rectification and purification of styrene need to be performed under reduced pressure. In addition, the volatility of ethylbenzene and styrene are similar, the boiling point of ethylbenzene is 51.3 ℃ and 77.2 ℃ respectively under the conditions of absolute pressure of 5kPa and 15 kPa, the boiling point of styrene is 59.2 ℃ and 85.1 ℃ respectively, and the difference between the two pressures is only about 8 ℃. The separation difficulty of ethylbenzene and styrene is high, and in order to achieve the high separation effect of the ethylbenzene and the styrene, the rectification tower for directly separating the ethylbenzene and the styrene needs more theoretical plates, has large reflux ratio and has high equipment investment and operation energy consumption.
Disclosure of Invention
The invention provides a process method for separating ethylbenzene and styrene by extractive distillation, aiming at the defects in the prior art, so as to solve the problems in the prior art.
In order to achieve the above purpose, the technical scheme of the invention is realized as follows:
a process method for separating ethylbenzene and styrene by extractive distillation comprises the following steps:
step (1): the mixture of ethylbenzene and styrene to be separated enters an extraction rectifying tower from a raw material feed inlet of the extraction rectifying tower, N-methyl pyrrolidone is used as an extractant and enters the extraction rectifying tower from an extractant feed inlet of the extraction rectifying tower to carry out extraction rectifying, ethylbenzene is obtained at the top of the extraction rectifying tower, and the mixture of styrene and the extractant N-methyl pyrrolidone is arranged at the bottom of the extraction rectifying tower;
step (2): and (3) feeding the mixture of the styrene and the extractant obtained in the step (1) into a recovery rectifying tower from a raw material feed inlet of the recovery rectifying tower, separating the styrene from the extractant, obtaining the styrene at the top of the recovery rectifying tower, and obtaining the extractant at the bottom of the recovery rectifying tower.
Further, the extractant obtained at the bottom of the recovery rectifying tower in the step (2) is recycled.
Further, in the step (1), the mass flow ratio of the extractant to the mixture of ethylbenzene and styrene to be separated is 3-5.
Further, the operating pressure of the extractive distillation column in the step (1) is 1-5 kPa absolute pressure.
Further, in the step (1), the number of tower plates of the extractive distillation column is 40-50.
Further, the operation pressure of the recovery rectifying tower in the step (2) is 1-3 kPa absolute pressure.
Further, the number of the tower plates of the recovery rectifying tower in the step (2) is 30-40.
By adopting the technology, compared with the prior art, the invention has the following beneficial effects:
1. the invention adopts N-methyl pyrrolidone as an extraction rectification extractant, changes the gas-liquid balance relation between ethylbenzene and styrene, increases the volatility difference of ethylbenzene and styrene, and realizes the effective separation of ethylbenzene and styrene;
2. the extractant N-methyl pyrrolidone and the styrene used in the invention have no azeotropy, the two are easy to separate, the styrene can be obtained by simple separation through recovery and rectification, and the separated extractant can be recycled;
3. the extractant N-methyl pyrrolidone used in the invention can dissolve the polymer formed by thermal polymerization of the styrene monomer in the rectification process, thereby greatly reducing the occurrence of the problem that the polymer blocks the rectification tower, in particular the filler or the tower plate and the reboiler through which the N-methyl pyrrolidone flows;
4. the invention only uses two groups of rectifying towers, has simple process and good economy, and is particularly suitable for continuous industrial production.
Drawings
FIG. 1 is a schematic process flow diagram of the method of the present invention.
Detailed Description
The invention is further illustrated by the following specific examples, which are intended to illustrate the problem and to explain the invention, without limiting it.
The process flow of each of the following examples is shown in FIG. 1, wherein 1 is an extractive distillation column and 2 is a recovery distillation column. The method comprises the steps of injecting a mixture of ethylbenzene and styrene into a raw material feed port at a position a, injecting an extractant into an extractant feed port at a position b, forming a mixture of styrene and N-methylpyrrolidone at the bottom of an extraction rectifying tower at a position c, obtaining ethylbenzene at the top of the extraction rectifying tower at a position d, obtaining a recyclable extractant at the bottom of a recovery rectifying tower at a position e, and obtaining styrene at the top of the recovery rectifying tower at a position f.
Example 1:
a process for separating a mixture of ethylbenzene and styrene comprising the steps of:
in the first step, the mixture of ethylbenzene and styrene to be separated consists of: 42.542 wt% ethylbenzene and 57.458% styrene. The mixture to be separated with the flow rate of 120 kg/h enters an extraction rectifying tower with the tray number of 50 from a raw material feed inlet of a 30 th tray of the extraction rectifying tower, and the extractant N-methyl pyrrolidone with the flow rate of 600 kg/h enters the extraction rectifying tower from an extractant feed inlet of a 15 th tray of the extraction rectifying tower. The extractive distillation is operated under the condition of 1 kPa absolute pressure, the reflux ratio is 3, and the top of the extractive distillation tower is provided with 99.923 wt percent of ethylbenzene; the bottom of the extraction rectifying tower is a mixture of styrene and an extractant N-methyl pyrrolidone.
And secondly, feeding the mixture of the styrene and the N-methylpyrrolidone in the first step into a recovery rectifying tower with the number of plates of 40 from a raw material feed inlet of a 20 th plate of the recovery rectifying tower, and separating the N-methylpyrrolidone from the ethylbenzene. The recovery rectification is operated under the condition of absolute pressure of 1 kPa, the reflux ratio is 5, and the styrene with purity of 99.908 wt percent is obtained at the top of the recovery rectification tower; and recycling the N-methyl pyrrolidone with the purity of 99.945 wt percent at the bottom of the rectifying tower as an extractant.
Example 2:
a process for separating a mixture of ethylbenzene and styrene comprising the steps of:
in the first step, the mixture of ethylbenzene and styrene to be separated consists of: 42.542 wt% ethylbenzene and 57.458% styrene. The mixture to be separated with the flow rate of 120 kg/h enters the extractive distillation column of the column plate 45 from the raw material feed inlet of the column plate 25 of the extractive distillation column, and the extractant N-methyl pyrrolidone with the flow rate of 480 kg/h enters the extractive distillation column from the extractant feed inlet of the column plate 10 of the extractive distillation column. The extractive distillation is operated under the condition of absolute pressure of 3kPa, the reflux ratio is 3, and the top of the extractive distillation tower is provided with 99.748 wt percent of ethylbenzene; the bottom of the extraction rectifying tower is a mixture of styrene and an extractant N-methyl pyrrolidone.
And secondly, feeding the mixture of the styrene and the N-methylpyrrolidone in the first step into a recovery rectifying tower of a tower plate 35 from a raw material feed inlet of the 17 th tower plate of the recovery rectifying tower to separate the N-methylpyrrolidone from the ethylbenzene. The recovery rectification is operated under the condition of 2 kPa absolute pressure, the reflux ratio is 5, and the styrene with the purity of 99.872 wt percent is obtained at the top of the recovery rectification tower; and recycling the N-methyl pyrrolidone with the purity of 99.906 wt percent at the bottom of the rectifying tower as an extractant.
Example 3:
a process for separating a mixture of ethylbenzene and styrene comprising the steps of:
in the first step, the mixture of ethylbenzene and styrene to be separated consists of: 42.542 wt% ethylbenzene and 57.458% styrene. The mixture to be separated with the flow rate of 120 kg/h enters an extraction rectifying tower with the number of plates of 40 from a raw material feed inlet of a 20 th plate of the extraction rectifying tower, and the extractant N-methyl pyrrolidone with the flow rate of 360 kg/h enters the extraction rectifying tower from an extractant feed inlet of a 5 th plate of the extraction rectifying tower. The extractive distillation is operated under the condition of absolute pressure of 5kPa, the reflux ratio is 3, and the top of the extractive distillation tower is provided with 99.627 wt percent of ethylbenzene; the bottom of the extraction rectifying tower is a mixture of styrene and an extractant N-methyl pyrrolidone.
And secondly, feeding the mixture of the styrene and the N-methylpyrrolidone in the first step into a recovery rectifying tower of a tower plate 30 from a raw material feed inlet of the 15 th tower plate of the recovery rectifying tower, and separating the N-methylpyrrolidone from the ethylbenzene. The recovery rectification is operated under the condition of absolute pressure of 3kPa, the reflux ratio is 5, and the styrene with purity of 99.814 wt percent is obtained at the top of the recovery rectification tower; and recycling the N-methyl pyrrolidone with the purity of 99.836 wt percent at the bottom of the rectifying tower as an extractant.
The data summary table of the embodiment of the invention is as follows:
according to the table 1, the purity of the ethylbenzene and the styrene obtained by separation by adopting the process method of the invention is high, the N-methyl pyrrolidone is adopted as an extraction rectification extractant, the gas-liquid equilibrium relation between the ethylbenzene and the styrene is changed, the volatility difference between the ethylbenzene and the styrene is increased, and the effective separation of the ethylbenzene and the styrene is realized; the N-methyl pyrrolidone and the styrene have no azeotropy, the N-methyl pyrrolidone and the styrene are easy to separate, and the N-methyl pyrrolidone obtained at the bottom of the recovery rectifying tower can be recycled; the N-methyl pyrrolidone can dissolve the polymer formed by thermal polymerization of the styrene monomer in the rectification process, so that the problem that the rectifying tower is blocked by the polymer is greatly reduced, and particularly, the filler or the tower plate and the reboiler through which the N-methyl pyrrolidone flows are provided.
The foregoing description is only of the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (7)
1. The process method for separating ethylbenzene and styrene by extractive distillation is characterized by comprising the following steps of:
step (1): the mixture of ethylbenzene and styrene to be separated enters an extraction rectifying tower from a raw material feed inlet of the extraction rectifying tower, N-methyl pyrrolidone is used as an extractant and enters the extraction rectifying tower from an extractant feed inlet of the extraction rectifying tower to carry out extraction rectifying, ethylbenzene is obtained at the top of the extraction rectifying tower, and the mixture of styrene and the extractant is at the bottom of the extraction rectifying tower;
step (2): and (3) feeding the mixture of the styrene and the extractant obtained in the step (1) into a recovery rectifying tower from a raw material feed inlet of the recovery rectifying tower, separating the styrene from the extractant, obtaining the styrene at the top of the recovery rectifying tower, and obtaining the extractant at the bottom of the recovery rectifying tower.
2. The process for separating ethylbenzene and styrene by extractive distillation as claimed in claim 1, wherein in step (2), the extractant obtained at the bottom of the recovery rectifying column is recycled.
3. The process for separating ethylbenzene and styrene by extractive distillation according to claim 2, wherein in the step (1), the mass flow ratio of the extractant to the mixture of ethylbenzene and styrene to be separated is 3-5.
4. The process for separating ethylbenzene and styrene by extractive distillation as claimed in claim 3, wherein in step (1), the operating pressure of the extractive distillation column is 1 to 5kPa absolute.
5. The process for separating ethylbenzene and styrene by extractive distillation as claimed in claim 4, wherein in step (1), the number of plates of the extractive distillation column is 40 to 50.
6. The process for separating ethylbenzene and styrene by extractive distillation as claimed in claim 5, wherein in step (2), the operation pressure of the recovery distillation column is 1 to 3kPa absolute.
7. The process for separating ethylbenzene and styrene by extractive distillation as claimed in claim 6, wherein in step (2), the number of plates of the recovery distillation column is 30 to 40.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202311818619.9A CN117776847A (en) | 2023-12-27 | 2023-12-27 | Process method for separating ethylbenzene and styrene by extractive distillation |
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| CN202311818619.9A CN117776847A (en) | 2023-12-27 | 2023-12-27 | Process method for separating ethylbenzene and styrene by extractive distillation |
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101759520A (en) * | 2008-12-25 | 2010-06-30 | 中国石油化工股份有限公司 | Method for extracting, rectifying and separating phenylethylene from hydrocarbon mixture |
| US20110015460A1 (en) * | 2009-07-17 | 2011-01-20 | Zhongyi Ding | Processes and systems for recovery of styrene from a styrene-containing feedstock |
| CN102190555A (en) * | 2010-03-03 | 2011-09-21 | 中国石油化工股份有限公司 | Method for recovering styrene |
| CN102452891A (en) * | 2010-10-25 | 2012-05-16 | 中国石油化工股份有限公司 | Method for separating styrene through extractive distillation |
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2023
- 2023-12-27 CN CN202311818619.9A patent/CN117776847A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101759520A (en) * | 2008-12-25 | 2010-06-30 | 中国石油化工股份有限公司 | Method for extracting, rectifying and separating phenylethylene from hydrocarbon mixture |
| US20110015460A1 (en) * | 2009-07-17 | 2011-01-20 | Zhongyi Ding | Processes and systems for recovery of styrene from a styrene-containing feedstock |
| CN102190555A (en) * | 2010-03-03 | 2011-09-21 | 中国石油化工股份有限公司 | Method for recovering styrene |
| CN102452891A (en) * | 2010-10-25 | 2012-05-16 | 中国石油化工股份有限公司 | Method for separating styrene through extractive distillation |
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