Continuous separation and purification method of 2, 4-dichlorophenol reaction mixed liquid

By adopting continuous separation and purification methods during the separation and purification process of 2,4-dichlorophenol, the problems of long residence time, high energy consumption and low production capacity in the prior art are solved, and efficient and stable production of 2,4-dichlorophenol is achieved, meeting the market demand for high-quality products.

CN119822927APending Publication Date: 2025-04-15LABOR KAIFENG AGROCHEMICALS CO LTD
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Patent Information

Application Number
CN202411605197.1
Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
Filing Date
2024-11-09
Publication Date
2025-04-15

AI Technical Summary

Technical Problem

The existing intermittent tower separation 2,4-dichlorophenol technology has long material residence time, high energy consumption, and low production capacity, and will cause material thermal sensitivity problems, resulting in unstable product quality and cannot meet the market's demand for high-quality 2,4-dichlorophenol.

Method used

The continuous separation and purification method of 2,4-dichlorophenol reaction mixed liquid is adopted, including two steps: crude division and purification. First, the mixed liquid after the reaction of phenol or mixed phenol and chlorine gas is fed into a 2,4-dichlorophenol crude separation column for heating and pressure separation to obtain a crude product containing more than 99% of 2,4-dichlorophenol. Then, the crude product was sent to the 2,4-dichlorophenol purification tower for further refining, and the finished product 2,4-dichlorophenol was extracted through continuous side lines to achieve a purity of more than 99.8%.

Benefits of technology

It has achieved the shortening of material residence time, the reduction of energy consumption, the improvement of output and the reduction of material thermal sensitivity problems, improved the quality stability of 2,4-dichlorophenol, and met the demand of the high-end market.

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Abstract

The invention relates to a continuous separation and purification method of a 2, 4-dichlorophenol reaction mixed liquid, which comprises the following steps of: feeding phenol or mixed phenol and the mixed liquid obtained by reacting with chlorine into a 2, 4-dichlorophenol crude separation tower, heating, pressurizing and separating, extracting the mixed phenol from the upper part of the 2, 4-dichlorophenol crude separation tower, extracting the 2, 4-dichlorophenol from the tower bottom, feeding the 2, 4-dichlorophenol into a 2, 4-dichlorophenol refining tower, and purifying the 2, 4-dichlorophenol. The 2, 4-dichlorophenol crude separation tower and the 2, 4-dichlorophenol refining tower are sequentially connected according to the step (1) and the step (2), and the step (1) and the step (2) are continuously carried out; the method is continuously carried out, the retention time of the materials is short, the energy consumption can be reduced, the yield can be increased, the heat sensitivity of the materials can be reduced as much as possible, and the quality stability of the 2, 4-dichlorophenol can be improved.
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Description

Technical Field

[0001] The invention relates to the technical field of 2,4-dichlorophenol separation, and in particular to a method for continuously separating and purifying a 2,4-dichlorophenol reaction mixed liquid. Background Art

[0002] 2,4-Dichlorophenol is an organic compound with the chemical formula C6H4Cl2O. It is a white crystalline powder. It is insoluble in water but soluble in organic solvents such as ethanol, ether, chloroform, and benzene. It is mainly used as a pesticide and pharmaceutical intermediate for the synthesis of herbicides, 2,4-D, etc. It can also be used as a solvent.

[0003] The technology of preparing 2,4-dichlorophenol by substitution reaction of mixed phenol and chlorine has been researched and developed in my country since the late 1960s, and has been industrialized. However, with the continuous expansion of market demand and increasingly stringent requirements for high product quality, the existing intermittent tower separation technology of 2,4-dichlorophenol has the problems of long material residence time, high energy consumption, low production capacity, and thermal sensitivity of materials, resulting in unstable product quality. It can no longer meet the market demand for high-quality 2,4-dichlorophenol. It is necessary to propose new separation and purification methods to address these problems. Summary of the invention

[0004] The purpose of the present invention is to solve the above problems and provide a method for continuously separating and purifying a 2,4-dichlorophenol reaction mixed liquid.

[0005] The technical solution of the present invention is: a method for continuously separating and purifying a 2,4-dichlorophenol reaction mixed liquid, comprising the following steps:

[0006] Step ① 2,4-dichlorophenol crude fraction

[0007] The mixed liquid after the reaction of phenol or mixed phenol and chlorine is sent to a 2,4-dichlorophenol crude fractionation tower, heated, and pressurized for separation, and the mixed phenol is extracted from the upper part of the 2,4-dichlorophenol crude fractionation tower, wherein the content of o-chlorophenol in the mixed phenol extracted here is greater than or equal to 60%; 2,4-dichlorophenol is extracted from the bottom of the tower, wherein the content of 2,4-dichlorophenol extracted here is greater than or equal to 99%;

[0008] Step ② Refining of 2,4-dichlorophenol

[0009] The dichlorophenol taken out from the bottom of the 2,4-dichlorophenol crude fraction tower is sent to a 2,4-dichlorophenol refining tower for heating and pressure refining. A mixed phenol is taken out from the top of the 2,4-dichlorophenol refining tower. The mixed phenol contains phenol, o-chlorophenol and 2,4-dichlorophenol. The finished product 2,4-dichlorophenol is taken out from the upper side line. The content of 2,4-dichlorophenol is greater than or equal to 99.8%. The bottoms are continuously discharged to the next process.

[0010] The 2,4-dichlorophenol crude fraction tower and the 2,4-dichlorophenol refining tower are sequentially connected according to the above steps ①②, and the above steps ①② are continuously performed.

[0011] Preferably, the mixed liquid obtained after the reaction of phenol or mixed phenols with chlorine in step ① contains the following components in parts by weight: 0.1 to 1.0 parts by weight of o-chlorophenol, 0.04 to 0.08 parts by weight of p-chlorophenol, 90.0 to 95.0 parts by weight of 2,4-dichlorophenol, 1.0 to 4.0 parts by weight of 2,6-dichlorophenol, 1.0 to 4.0 parts by weight of 2,4,6-trichlorophenol, and 0.05 to 0.4 parts by weight of tar.

[0012] Preferably, in the step ①, the top pressure of the 2,4-dichlorophenol crude fraction tower is 2-4 KPa, and the bottom pressure is 1-2 KPa higher than the top pressure; the top temperature is 85-120°C, and the bottom temperature is 130-150°C.

[0013] Preferably, in the step ②, the top pressure of the 2,4-dichlorophenol refining tower is 2-4 KPa, and the bottom pressure is 1-2 KPa higher than the top pressure; the top temperature is 93-120°C, and the bottom temperature is 130-150°C.

[0014] Preferably, the 2,4-dichlorophenol crude fraction tower and the 2,4-dichlorophenol refining tower are both high-efficiency packed towers, and their reboilers are both vertical tube-in-tube thermosyphon heat exchangers, which have the effect of energy saving and consumption reduction.

[0015] Preferably, the reflux ratio of the 2,4-dichlorophenol crude fraction tower is 1.5 to 2.2, and that of the 2,4-dichlorophenol refining tower is 2.4 to 2.6.

[0016] Preferably, the speed at which the mixed liquid described in step ① is fed into the crude o-chlorophenol tower is 1200-1600 Kg / h.

[0017] The beneficial effects of the present invention are:

[0018] A method for continuously separating and purifying a mixed liquid of a 2,4-dichlorophenol reaction comprises the following steps: feeding phenol or a mixed phenol and a mixed liquid after reacting with chlorine into a 2,4-dichlorophenol crude fraction tower, heating, pressurizing and separating, extracting mixed phenol from the upper part of the 2,4-dichlorophenol crude fraction tower, extracting 2,4-dichlorophenol from the bottom of the tower and feeding it into a 2,4-dichlorophenol refining tower, heating, pressurizing and refining, extracting mixed phenol from the top of the 2,4-dichlorophenol refining tower, extracting finished 2,4-dichlorophenol from the upper side line, and continuously discharging the bottom of the tower to the next process, the 2,4-dichlorophenol crude fraction tower and the 2,4-dichlorophenol refining tower are sequentially connected according to the above steps ①②, and the above steps ①② are continuously performed; the method is continuously performed, wherein the material residence time is short, the energy consumption can be reduced, the output can be increased, the thermal sensitivity of the material can be reduced as much as possible, the generation of tar can be reduced, and the stability of the quality of 2,4-dichlorophenol can be improved.

[0019] 1. The evaporator of this method adopts a vertical thermosyphon heat exchanger, which has high heat exchange efficiency, energy saving, small footprint and low investment compared with the prior art that uses a horizontal distillation kettle for heating in intermittent distillation;

[0020] 2. This method uses continuous distillation separation, which increases the capacity by 40% compared with the intermittent distillation in the prior art;

[0021] 2. This method uses continuous distillation separation, which has a shorter residence time of materials and reduced thermal sensitivity compared to the intermittent distillation in the prior art;

[0022] 4. This method adopts continuous side-line extraction of 2,4-dichlorophenol, which improves and stabilizes the product quality compared with the intermittent distillation tower top extraction in the prior art;

[0023] 5. This method uses continuous distillation separation, which requires fewer people than intermittent distillation and is conducive to automated operation;

[0024] 6. This method uses continuous distillation separation, which reduces energy consumption compared to intermittent distillation;

[0025] 7. The purpose of the present invention is to overcome the deficiencies of the prior art and provide a method for continuously separating 2,4-dichlorophenol reaction mixed liquid, which is energy-saving and consumption-reducing, easy to operate, and has products that meet the needs of the high-end market. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The present invention is a process flow chart of the method for continuous separation and purification of 2,4-dichlorophenol reaction mixed liquid. DETAILED DESCRIPTION

[0027] Example 1: See Figure 1 A method for continuously separating and purifying a 2,4-dichlorophenol reaction mixed liquid comprises the following steps:

[0028] Step ① 2,4-dichlorophenol crude fraction

[0029] The mixed liquid after the reaction of phenol or mixed phenol and chlorine is sent to a 2,4-dichlorophenol crude fractionation tower, heated, and pressurized for separation. The mixed liquid here contains the following components calculated by weight: 0.30 weight parts of o-chlorophenol, 0.04 weight parts of p-chlorophenol, 3.50 weight parts of 2,6-dichlorophenol, 93.17 weight parts of 2,4-dichlorophenol, 3.05 weight parts of 2,4,6-trichlorophenol, and 0.4 weight parts of tar; the mixed liquid is sent to the 2,4-dichlorophenol crude fractionation tower at 1200 kg / h;

[0030] 8.5 kg / h of mixed phenol was extracted from the upper part of the crude 2,4-dichlorophenol fraction tower, and the following components were detected: o-chlorophenol content was 70.6% and 2,4-dichlorophenol content was 29.4%; 2,4-dichlorophenol was extracted from the bottom of the crude 2,4-dichlorophenol tower, and the content of 2,4-dichlorophenol extracted here was greater than or equal to 99%, and was continuously fed into the 2,4-dichlorophenol refining tower at 1191.5 kg / h;

[0031] The 2,4-dichlorophenol crude fraction tower is a high-efficiency packed tower, and its reboilers are all vertical tube-and-tube thermosyphon heat exchangers. The top pressure / temperature of the 2,4-dichlorophenol crude fraction tower is 2.8Kpa / 95°C, and the bottom pressure / temperature is 3.83Kpa / 138°C; the reflux ratio is controlled at 2.2.

[0032] Step ② Refining of 2,4-dichlorophenol

[0033] The dichlorophenol extracted from the bottom of the 2,4-dichlorophenol crude fraction tower is sent to a 2,4-dichlorophenol refining tower, heated, and pressurized for refining. The top of the 2,4-dichlorophenol refining tower extracts 6.42 kg / h of mixed phenol, and the components thereof are detected as follows: 15.4% phenol content, 1.86% o-chlorophenol content, 77.2% 2,4-dichlorophenol content, and 4.54% crude 2,6-dichlorophenol content;

[0034] The upper line produces 1082 kg / h of finished 2,4-dichlorophenol, and the components are tested as follows: phenol content 0.01%, 2,4-dichlorophenol content 99.82%, 2,6-dichlorophenol content 0.16%, p-chlorophenol 0.01%, achieving the refining and purification of 2,4-dichlorophenol with a purity greater than or equal to 99.8%, and removing tar.

[0035] 103.8 kg / h of the bottom product is sent to the next process. Most of the bottom product is tar, in which the content of 2,4-dichlorophenol is less than 10%.

[0036] The 2,4-dichlorophenol refining tower is a high-efficiency packed tower, and its reboilers are all vertical tube-and-tube thermosyphon heat exchangers. The top pressure / temperature of the 2,4-dichlorophenol refining tower is 2.7Kpa / 93°C, and the bottom pressure / temperature is 3.80Kpa / 135°C; the reflux ratio is controlled at 2.4.

[0037] The 2,4-dichlorophenol crude fraction tower and the 2,4-dichlorophenol refining tower are sequentially connected according to the above steps ①②, and the above steps ①② are continuously performed.

[0038] Example 2: See Figure 1 A method for continuously separating and purifying a 2,4-dichlorophenol reaction mixed liquid comprises the following steps:

[0039] Step ① 2,4-dichlorophenol crude fraction

[0040] The mixed liquid after the reaction of phenol or mixed phenol and chlorine is sent to a 2,4-dichlorophenol crude fractionation tower, heated, and pressurized for separation. The mixed liquid here contains the following components calculated by weight: 0.51 weight parts of o-chlorophenol, 0.08 weight parts of p-chlorophenol, 3.79 weight parts of 2,6-dichlorophenol, 91.97 weight parts of 2,4-dichlorophenol, 3.25 weight parts of 2,4,6-trichlorophenol, and 0.4 weight parts of tar; the mixed liquid is sent to the 2,4-dichlorophenol crude fractionation tower at 1600 kg / h;

[0041] 12.0 kg / h of mixed phenol was extracted from the upper part of the crude 2,4-dichlorophenol fraction tower, and the following components were detected: o-chlorophenol content 65.0%, 2,4-dichlorophenol content 35.0%; 2,4-dichlorophenol was extracted from the bottom of the crude 2,4-dichlorophenol tower, and the content of 2,4-dichlorophenol extracted here was greater than or equal to 99%, and was continuously fed into the 2,4-dichlorophenol refining tower at 1588 kg / h;

[0042] The 2,4-dichlorophenol crude fraction tower is a high-efficiency packed tower, and its reboilers are all vertical tube-and-tube thermosyphon heat exchangers. The top pressure / temperature of the 2,4-dichlorophenol crude fraction tower is 3.1 Kpa / 102°C, and the bottom pressure / temperature is 4.3 Kpa / 142°C; the reflux ratio is controlled to be 1.5.

[0043] Step ② 2,4-dichlorophenol purification

[0044] The dichlorophenol extracted from the bottom of the 2,4-dichlorophenol crude fraction tower is sent to a 2,4-dichlorophenol refining tower, heated, and pressurized for refining. The top of the 2,4-dichlorophenol refining tower extracts 12.0 kg / h of mixed phenol, and the components thereof are detected as follows: 10.2% phenol content, 26.3% o-chlorophenol content, 58.7% 2,4-dichlorophenol content, and 4.8% 2,6-dichlorophenol content;

[0045] The upper line produces 1380 kg / h of finished product 2,4-dichlorophenol, and the components are tested as follows: phenol content 0.02%, 2,4-dichlorophenol content 99.90%, 2,6-dichlorophenol content 0.05%, p-chlorophenol 0.03%, and the refining and purification of 2,4-dichlorophenol is greater than 99.8%, and the tar is removed.

[0046] The bottoms are sent to the next step at a rate of 196.0 kg / h. Most of the bottoms are tar, in which the content of 2,4-dichlorophenol is less than 10%.

[0047] The 2,4-dichlorophenol refining tower is a high-efficiency packed tower, and its reboilers are all vertical tube-and-tube thermosyphon heat exchangers. The top pressure / temperature of the 2,4-dichlorophenol refining tower is 2.9Kpa / 97°C, and the bottom pressure / temperature is 3.920Kpa / 142°C; the reflux ratio is controlled to be 2.6. The 2,4-dichlorophenol crude fraction tower and the 2,4-dichlorophenol refining tower are connected in sequence according to the above steps ①②, and the above steps ①② are performed continuously.

Claims

1. A method for continuous separation and purification of a 2,4-dichlorophenol reaction mixed liquid, comprising the following steps: Step ① 2,4-dichlorophenol crude fraction The mixed liquid after the reaction of phenol or mixed phenol and chlorine is sent to a 2,4-dichlorophenol crude fractionation tower, heated, pressurized and separated, and the mixed phenol is extracted from the upper part of the 2,4-dichlorophenol crude fractionation tower; and 2,4-dichlorophenol is extracted from the bottom of the tower; Step ② Refining of 2,4-dichlorophenol The dichlorophenol extracted from the bottom of the 2,4-dichlorophenol crude fraction tower is sent to a 2,4-dichlorophenol refining tower, heated, and pressurized for refining. The top of the 2,4-dichlorophenol refining tower extracts mixed phenol, and the finished product 2,4-dichlorophenol is extracted from the upper side line. The bottoms are continuously discharged to the next process. The 2,4-dichlorophenol crude fraction tower and the 2,4-dichlorophenol refining tower are sequentially connected according to the above steps ①②, and the above steps ①② are continuously performed.

2. A method for continuous separation and purification of a 2,4-dichlorophenol reaction mixed liquid according to claim 1, characterized in that: The mixed liquid obtained after the reaction of phenol or mixed phenol with chlorine in step ① contains the following components in parts by weight: 0.1 to 1.0 parts by weight of o-chlorophenol, 0.04 to 0.08 parts by weight of p-chlorophenol, 90.0 to 95.0 parts by weight of 2,4-dichlorophenol, 1.0 to 4.0 parts by weight of 2,6-dichlorophenol, 1.0 to 4.0 parts by weight of 2,4,6-trichlorophenol, and 0.05 to 0.4 parts by weight of tar.

3. A method for continuous separation and purification of a 2,4-dichlorophenol reaction mixed liquid according to claim 1, characterized in that: In the step ①, the top pressure of the 2,4-dichlorophenol crude fraction tower is 2-4 KPa, and the bottom pressure is 1-2 KPa higher than the top pressure; the top temperature is 85-120°C, and the bottom temperature is 130-150°C.

4. A method for continuous separation and purification of a 2,4-dichlorophenol reaction mixed liquid according to claim 1, characterized in that: In the step ②, the top pressure of the 2,4-dichlorophenol refining tower is 2-4KPa, and the bottom pressure is 1-2KPa higher than the top pressure; the top temperature is 93-120°C, and the bottom temperature is 130-150°C.

5. A method for continuous separation and purification of a 2,4-dichlorophenol reaction mixed liquid according to claim 1, characterized in that: The 2,4-dichlorophenol crude fractionation tower and the 2,4-dichlorophenol refining tower are both high-efficiency packed towers, and their reboilers are both vertical tube-in-tube thermosyphon heat exchangers.

6. A method for continuous separation and purification of a 2,4-dichlorophenol reaction mixed liquid according to claim 5, characterized in that: The reflux ratio of the 2,4-dichlorophenol crude fraction tower is 1.5-2.2, and that of the 2,4-dichlorophenol refining tower is 2.4-2.

6.

7. A method for continuous separation and purification of a 2,4-dichlorophenol reaction mixed liquid according to claim 1, characterized in that: The speed at which the mixed liquid described in step ① is fed into the crude o-chlorophenol tower is 1200~1600Kg / h.