CN109824485B - Method for separating 2, 6-xylenol by using partition tower - Google Patents
Method for separating 2, 6-xylenol by using partition tower Download PDFInfo
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- CN109824485B CN109824485B CN201910263502.6A CN201910263502A CN109824485B CN 109824485 B CN109824485 B CN 109824485B CN 201910263502 A CN201910263502 A CN 201910263502A CN 109824485 B CN109824485 B CN 109824485B
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- xylenol
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- separation
- cresol
- phenol
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- NXXYKOUNUYWIHA-UHFFFAOYSA-N 2,6-Dimethylphenol Chemical compound CC1=CC=CC(C)=C1O NXXYKOUNUYWIHA-UHFFFAOYSA-N 0.000 title claims abstract description 102
- 238000000034 method Methods 0.000 title claims abstract description 18
- 238000005192 partition Methods 0.000 title description 4
- ISWSIDIOOBJBQZ-UHFFFAOYSA-N phenol group Chemical group C1(=CC=CC=C1)O ISWSIDIOOBJBQZ-UHFFFAOYSA-N 0.000 claims abstract description 39
- 238000000926 separation method Methods 0.000 claims abstract description 33
- 230000015572 biosynthetic process Effects 0.000 claims abstract description 3
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims description 57
- QWVGKYWNOKOFNN-UHFFFAOYSA-N o-cresol Chemical compound CC1=CC=CC=C1O QWVGKYWNOKOFNN-UHFFFAOYSA-N 0.000 claims description 52
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 11
- 239000007795 chemical reaction product Substances 0.000 claims description 8
- 239000000047 product Substances 0.000 claims description 8
- 238000005804 alkylation reaction Methods 0.000 claims description 7
- 238000010992 reflux Methods 0.000 claims description 7
- 230000006837 decompression Effects 0.000 claims description 6
- 239000000203 mixture Substances 0.000 claims description 6
- XRUGBBIQLIVCSI-UHFFFAOYSA-N 2,3,4-trimethylphenol Chemical compound CC1=CC=C(O)C(C)=C1C XRUGBBIQLIVCSI-UHFFFAOYSA-N 0.000 claims description 5
- 230000029936 alkylation Effects 0.000 claims description 2
- 238000011084 recovery Methods 0.000 claims description 2
- 239000007792 gaseous phase Substances 0.000 claims 1
- 238000003786 synthesis reaction Methods 0.000 claims 1
- 238000004939 coking Methods 0.000 abstract description 4
- 238000005265 energy consumption Methods 0.000 abstract description 4
- 239000000126 substance Substances 0.000 abstract description 2
- 238000001308 synthesis method Methods 0.000 abstract description 2
- 150000002989 phenols Chemical class 0.000 description 8
- 239000000463 material Substances 0.000 description 6
- 238000005194 fractionation Methods 0.000 description 4
- 230000002194 synthesizing effect Effects 0.000 description 4
- 150000003739 xylenols Chemical class 0.000 description 4
- 238000004364 calculation method Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000014759 maintenance of location Effects 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 238000006116 polymerization reaction Methods 0.000 description 2
- 229920013636 polyphenyl ether polymer Polymers 0.000 description 2
- 238000007670 refining Methods 0.000 description 2
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 238000003442 catalytic alkylation reaction Methods 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000001335 demethylating effect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 229920006351 engineering plastic Polymers 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 150000004706 metal oxides Chemical class 0.000 description 1
- 239000000178 monomer Substances 0.000 description 1
- 238000004088 simulation Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
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- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
The invention aims to provide a more efficient and energy-saving 2, 6-xylenol synthesis and separation method. Compared with the common two-tower vacuum rectification, the invention can shorten the rectification flow, reduce the coking of phenolic substances, better solve the energy consumption problem in the rectification process, simplify the operation and greatly reduce the equipment investment.
Description
Technical Field
The invention relates to a method for separating 2, 6-xylenol by using a dividing wall tower, in particular to a method for separating high-purity 2, 6-xylenol by adopting a decompression dividing wall tower to obtain a mixed phenol of a reaction product of synthesizing 2, 6-xylenol by gas phase alkylation of phenol and methanol after methanol and water removal.
Background
2, 6-xylenol is a monomer for synthesizing polyphenyl ether, and the polyphenyl ether is engineering plastic with excellent performance and wide application. The 2, 6-xylenol can be prepared by ortho-alkylating phenol or o-cresol with methanol, and the reaction is carried out in a fixed bed reactor by using a composite metal oxide as a catalyst. The reaction product of synthesizing 2, 6-xylenol by gas phase catalytic alkylation of methanol and phenol or o-cresol contains water, methanol, phenol, o-cresol, 2, 6-xylenol and a small amount of tricresyl, and after methanol and water are removed, a phenol multi-component system is left. Because the multi-element system belongs to homologues, the boiling point difference is very small (phenol 181.8 ℃, o-cresol 191 ℃,2, 6-xylenol 200.9 ℃), and the purity requirement is difficult to reach by adopting a common sieve plate tower. Theoretical calculation and calculation simulation show that in order to meet the requirement of separating o-cresol and 2, 6-xylenol, the number of tower plates of the rectifying tower must be more than 70, and the reflux ratio is about 10; the traditional method for refining 2, 6-xylenol can achieve the required separation effect by at least two towers, but the method has long process flow, high energy consumption, long liquid retention time, easy polymerization and coking of phenolic compounds, inconvenient operation caused by long separation flow and large equipment investment. Therefore, a more efficient and energy-saving method for synthesizing and rectifying the 2, 6-xylenol is needed.
Disclosure of Invention
The invention aims to provide a more efficient and energy-saving 2, 6-xylenol synthesis and separation method. In the method of the invention, after the alkylation reaction of phenol and methanol, the reaction product contains water, methanol, phenol, o-cresol, 2, 6-xylenol and a small amount of tricresyl, and after the methanol and water of the product are removed, a mixed system of a plurality of phenols is left. The conventional method for separating 2, 6-xylenol is generally adopted, at least two towers are needed to achieve the required separation effect, the first tower is used for removing the recycled phenol and o-cresol, and the second tower is used for refining the 2, 6-xylenol. Although the separation process can obtain high-purity 2, 6-xylenol, the method has long process flow, high energy consumption, higher tower kettle temperature and long phenol retention time, and is easy to cause polymerization coking of phenolic compounds. Aiming at the defects in the existing rectification process, the invention provides a novel energy-saving method for obtaining a high-purity 2, 6-xylenol product by utilizing a single-bulkhead tower to separate phenol, o-cresol, 2, 6-xylenol and a small amount of tricresyl under reduced pressure. The method adopts single-tower continuous rectification, and the vertical wall is utilized to divide the bulkhead tower into four working sections; the mixture of various phenols to be separated enters from the middle part of the prefractionation section, the separation of the o-cresol is completed in the main tower section (2), the o-cresol in the tower does not enter the public stripping section (3), the separation of the 2, 6-xylenol and the tricresyl is completed in the public stripping section (3), the separation of the o-cresol and the 2, 6-xylenol is completed in the public rectifying section (1), the light component (D) phenol and the o-cresol are recovered from the top of the rectifying tower, the high-purity 2, 6-xylenol product (S) is recovered from the side line in the middle part of the main tower section (4) of the rectifying tower, and the heavy component tricresyl (W) is recovered from the bottom of the rectifying tower, thereby realizing the separation of the multi-component phenol.
The weight fraction of 2, 6-xylenol in the mixed phenol after the demethylating alcohol and the water which are suitable for the partition tower is not less than 50%, the content of o-cresol is not more than 45%, and the content of trimethylphenol is not more than 5%.
In the separation technical scheme, the reflux ratio of the top of the bulkhead tower is 5-12.
In the separation technical scheme, 30-50 theoretical plates are respectively arranged on two sides of a vertical wall (5) of the partition tower.
In the separation technical scheme, 20-30 theoretical plates are arranged in the public rectifying section (1) above the vertical wall.
In the separation technical scheme, a public stripping section (3) below the vertical wall is provided with 15-25 theoretical plates.
In the separation technical scheme, the operating pressure of the dividing wall column is 5-20 kPa (absolute pressure).
In the separation technical scheme, after the pressure reduction separation in a bulkhead column, the purity of the 2, 6-xylenol can reach more than 99.5%, and the recovery rate of the 2, 6-xylenol in the column is more than 95%.
Compared with the common two-tower vacuum rectification, the method can shorten the rectification flow, reduce the coking of phenolic substances, better solve the energy consumption problem in the rectification process, simplify the operation and greatly reduce the equipment investment under the same separation requirement.
Drawings
FIG. 1 is a schematic flow diagram of a divided wall column of the present invention.
In fig. 1: 1-a public rectifying section; 2-a main tower section; 3-public stripping section; 4-a main tower section; 5-a rectifying tower separator; 6-an overhead condenser; 7-a bottom reboiler; f-feeding; d, collecting materials from the tower top; s-side offtake; collecting materials in the W-tower kettle.
The present invention will be described in further detail below. The following examples are merely illustrative of the present invention and are not intended to represent or limit the scope of the invention as defined in the claims.
Detailed Description
Example 1
After alkylation reaction of phenol and methanol, the reaction product is subjected to methanol and water removal, and a mixed system of various phenols is left, wherein the mixed system contains 4% of phenol, 42% of o-cresol, 53% of 2, 6-xylenol and 1% of tricresyl. The mixture is continuously pumped into the middle part of a pre-fractionation section (2) of a decompression dividing wall column through a pump for separation, 47 theoretical plates are respectively arranged on two sides of a vertical wall (5) of the dividing wall column, 25 theoretical plates are arranged on an upper public rectification section (1) of the vertical wall, 20 theoretical plates are arranged on a lower public stripping section (3) of the vertical wall, the operating pressure of the column is 10kPa (absolute pressure), the reflux ratio of the top of the column is 6, the recycled material phenol and o-cresol are extracted from the top of the column, the content of 2, 6-xylenol is less than 3%, the heavy component xylenol is extracted from the bottom of the column, the content of 2, 6-xylenol is less than 5%, the 2, 6-xylenol product with the purity higher than 99.5% is extracted from the side line at the middle position on the right side of the vertical wall, and the yield is about 97%.
Example 2
After alkylation reaction of phenol and methanol, the reaction product is subjected to methanol and water removal, and a mixed system of various phenols is left, wherein the mixed system contains 1% of phenol, 26% of o-cresol, 70% of 2, 6-xylenol and 3% of trimethylphenol. The mixture is continuously pumped into the middle part of a pre-fractionation section (2) of a decompression dividing wall column through a pump for separation, 40 theoretical plates are respectively arranged on two sides of a vertical wall (5) of the dividing wall column, 27 theoretical plates are arranged on a public rectifying section (1) on the upper part of the vertical wall, 18 theoretical plates are arranged on a public stripping section (3) on the lower part of the vertical wall, the operating pressure of the column is 5kPa (absolute pressure), the reflux ratio of the top of the column is 8, the recycled material phenol and o-cresol are extracted from the top of the column, the content of 2, 6-xylenol is less than 3%, the heavy component xylenol is extracted from the bottom of the column, the content of 2, 6-xylenol is less than 5%, the 2, 6-xylenol product with the purity higher than 99.5% is extracted from the side line at the middle position on the right side of the vertical wall, and the yield is about 98%.
Example 3
After alkylation reaction of phenol and methanol, the reaction product is subjected to methanol and water removal, and a mixed system of various phenols is left, wherein the mixed system contains 0.1% of phenol, 6% of o-cresol, 91% of 2, 6-xylenol and 2.9% of trimethylphenol. The mixture is continuously pumped into the middle part of a pre-fractionation section (2) of a decompression dividing wall column through a pump for separation, 31 theoretical plates are respectively arranged on two sides of a vertical wall (5) of the dividing wall column, 22 theoretical plates are arranged on a public rectifying section (1) on the upper part of the vertical wall, 25 theoretical plates are arranged on a public stripping section (3) on the lower part of the vertical wall, the operating pressure of the column is 18kPa (absolute pressure), the reflux ratio of the top of the column is 10, the recycled material phenol and o-cresol are extracted from the top of the column, the content of 2, 6-xylenol is less than 5%, the heavy component xylenol is extracted from the bottom of the column, the content of 2, 6-xylenol is less than 5%, the 2, 6-xylenol product with the purity higher than 99.5% is extracted from the side line at the middle position on the right side of the vertical wall, and the yield is about 99%.
Example 4
After alkylation reaction of phenol and methanol, the reaction product is subjected to methanol and water removal, and a mixed system of various phenols is left, wherein the mixed system contains 0.8% of phenol, 14% of o-cresol, 83% of 2, 6-xylenol and 2.2% of trimethylphenol. The mixture is continuously pumped into the middle part of a pre-fractionation section (2) of a decompression dividing wall column through a pump for separation, 35 theoretical plates are respectively arranged on two sides of a vertical wall (5) of the dividing wall column, 24 theoretical plates are arranged on a public rectifying section (1) on the upper part of the vertical wall, 20 theoretical plates are arranged on a public stripping section (3) on the lower part of the vertical wall, the operating pressure of the column is 10kPa (absolute pressure), the reflux ratio of the top of the column is 12, the recycled material phenol and o-cresol are extracted from the top of the column, the content of 2, 6-xylenol is less than 3%, the heavy component xylenol is extracted from the bottom of the column, the content of 2, 6-xylenol is less than 5%, the 2, 6-xylenol product with the purity higher than 99.5% is extracted from the side line at the middle position on the right side of the vertical wall, and the yield is about 99%.
The foregoing is a specific embodiment of the present invention, and the present invention is not limited to the above embodiment. Any person skilled in the art will understand that, while the technical content disclosed above may be utilized to make some changes or modifications into equivalent embodiments without departing from the technical content of the present invention, any simple modification, equivalent substitution, improvement, etc. of the above embodiments within the spirit and principle of the present invention still fall within the protection scope of the technical solution according to the technical spirit of the present invention.
Claims (7)
1. A method for separating 2, 6-xylenol by using a dividing wall column, characterized in that: the mixed phenol of the reaction product of phenol and methanol after gaseous phase alkylation synthesis of 2, 6-xylenol is subjected to methanol and water removal, a decompression dividing wall column is adopted to carry out single-column continuous rectification, the dividing wall column is divided into four working sections by utilizing a vertical wall (5), a phenolic mixture (F) to be separated enters from the middle part of a prefractionation section (2) to finish the separation of o-cresol, the o-cresol in the column does not enter a public stripping section (3), the separation of 2, 6-xylenol and tricresyl is finished in the public stripping section (3), the separation of the o-cresol and 2, 6-xylenol is finished in a public rectifying section (1), light component (D) phenol and o-cresol are recovered from the top of the rectifying column, high-purity 2, 6-xylenol products (S) are recovered from the side line in the middle part of a main tower section (4) of the rectifying column, and the tricresyl (W) is recovered from the bottom of the rectifying column, so that the separation of multi-component phenol is realized; the mass fraction of 2, 6-xylenol in the mixed phenol is not less than 50%, the content of o-cresol is not more than 45%, and the content of trimethylphenol is not more than 5%.
2. The separation method according to claim 1, wherein the reflux ratio of the top of the divided wall column is 5 to 12.
3. The separation method according to claim 1, wherein 30 to 50 theoretical plates are provided on both sides of the vertical wall (5) of the divided wall column.
4. The separation process according to claim 1, wherein the common rectifying section (1) above the vertical wall has 20 to 30 theoretical plates.
5. The separation method according to claim 1, wherein the common stripping section (3) below the vertical wall has 15 to 25 theoretical plates.
6. The separation method according to claim 1, wherein the pressure of the operation of the divided wall column is 5 to 20kPa.
7. The separation method according to claim 1, wherein the purity of 2, 6-xylenol is 99.5% or more and the recovery rate of 2, 6-xylenol in the column is 95% or more after the separation under reduced pressure in the divided column.
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Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0597739A (en) * | 1991-10-01 | 1993-04-20 | Asahi Chem Ind Co Ltd | Separation of ortho site-methylated phenolic compound |
| US5264085A (en) * | 1991-08-28 | 1993-11-23 | Mitsubishi Petrochemical Company, Ltd. | Method of separating components of phenols mixture by distillation |
| JP2005008556A (en) * | 2003-06-19 | 2005-01-13 | Asahi Kasei Chemicals Corp | Method for producing ortho-alkylated hydroxyaromatic compound |
| CN1974517A (en) * | 2006-12-08 | 2007-06-06 | 鞍钢股份有限公司 | Production method of phenol products |
| CN103319300A (en) * | 2013-07-05 | 2013-09-25 | 中国科学院大学 | Process method for preparing industrial naphthalene through continuous distillation |
| CN107556165A (en) * | 2017-08-18 | 2018-01-09 | 陕西煤业化工集团神木天元化工有限公司 | A kind of method and its device that 2,6 xylenols are extracted from crude phenols |
| CN207734629U (en) * | 2017-10-13 | 2018-08-17 | 中国石油化工集团公司 | A kind of next door rectifying column |
-
2019
- 2019-04-03 CN CN201910263502.6A patent/CN109824485B/en active Active
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5264085A (en) * | 1991-08-28 | 1993-11-23 | Mitsubishi Petrochemical Company, Ltd. | Method of separating components of phenols mixture by distillation |
| JPH0597739A (en) * | 1991-10-01 | 1993-04-20 | Asahi Chem Ind Co Ltd | Separation of ortho site-methylated phenolic compound |
| JP2005008556A (en) * | 2003-06-19 | 2005-01-13 | Asahi Kasei Chemicals Corp | Method for producing ortho-alkylated hydroxyaromatic compound |
| CN1974517A (en) * | 2006-12-08 | 2007-06-06 | 鞍钢股份有限公司 | Production method of phenol products |
| CN103319300A (en) * | 2013-07-05 | 2013-09-25 | 中国科学院大学 | Process method for preparing industrial naphthalene through continuous distillation |
| CN107556165A (en) * | 2017-08-18 | 2018-01-09 | 陕西煤业化工集团神木天元化工有限公司 | A kind of method and its device that 2,6 xylenols are extracted from crude phenols |
| CN207734629U (en) * | 2017-10-13 | 2018-08-17 | 中国石油化工集团公司 | A kind of next door rectifying column |
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Denomination of invention: A method for separating 2,6-dimethylphenol using a neighboring tower Granted publication date: 20231124 Pledgee: Northeast Small and Medium sized Enterprise Financing Re guarantee Co.,Ltd. Dalian Branch Pledgor: Dalian Zhongmu Chemical Co.,Ltd. Registration number: Y2024980006461 |
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