Method for separating ortho / parachlorophenol in phenol chlorination liquid

Abstract

The invention relates to a method for separating o-chlorophenol / p-chlorophenol from phenol chloride liquid, which comprises the following steps: (1) feeding mixed liquid obtained by reacting phenol and chlorine into a crude o-chlorophenol tower for heating and pressurized separation, extracting crude o-chlorophenol from the tower top, feeding the crude o-chlorophenol into an o-chlorophenol rectifying tower, and feeding crude p-chlorophenol from the tower bottom into a p-chlorophenol rectifying tower; (2) extracting a finished product o-chlorophenol from the top of the o-chlorophenol rectifying tower; (3) purifying the tower substrate of the parachlorophenol rectifying tower in a parachlorophenol refining tower; and (4) collecting the finished product parachlorophenol from the upper side line of the parachlorophenol refining tower, packaging in a receiving tank, and regularly discharging the tower substrate. According to the method, the steps (1), (2), (3) and (4) are continuously carried out, materials continuously flow, the retention time is short, the production efficiency is greatly improved, the energy consumption is reduced, the heat sensitivity problem of converting parachlorophenol into tar is reduced, and the quality stability of the produced product is improved.

Description

Technical Field

[0001] The invention relates to the technical field of separation of o-chlorophenol and p-chlorophenol, in particular to a method for separating o-chlorophenol and p-chlorophenol from phenol chlorination liquid. Background Art

[0002] o-Chlorophenol is a colorless liquid with a peculiar smell. It is slightly soluble in water and soluble in organic solvents such as ethanol and ether. It is used in organic synthesis. o-Chlorophenol is phosgenated to obtain o-chlorophenyl chloroformate, which is an intermediate of the carbamate insecticide chlorpyrifos.

[0003] Parachlorophenol, pure product is colorless crystal. It is very slightly soluble in water, soluble in benzene, ethanol and ether. It is used to make dyes and drugs, and is also used as a denaturant for alcohol and a selective solvent for refined mineral oil. It can also be used for microscopic analysis, pharmaceutical industry, and plant growth promoter.

[0004] my country has been researching and developing the technology of preparing o-chlorophenol / p-chlorophenol by substitution reaction of phenol with chlorine since the late 1960s, and has already put it into industrial production. However, with the continuous expansion of market demand and increasingly stringent requirements for product quality, the original intermittent tower separation technology of o-chlorophenol / p-chlorophenol has the problems of long material residence time, high energy consumption, low production efficiency, and the prominent problem of thermal sensitivity of p-chlorophenol, which affects the quality stability of the product. The above-mentioned problems can no longer meet the requirements of the existing market for these two products, and it is necessary to improve and upgrade the production methods. Summary of the invention

[0005] The object of the present invention is to solve the above problems and to provide a method for separating o-chlorophenol and p-chlorophenol in phenol chlorination liquid.

[0006] The technical solution of the present invention is: a method for separating o-chlorophenol / p-chlorophenol in phenol chlorination liquid, comprising the following steps:

[0007] Step ① Crude separation of o- / p-chlorophenol

[0008] The mixed liquid after the reaction of phenol and chlorine is sent to a crude o-chlorophenol tower for heating and pressurization separation, crude o-chlorophenol is extracted from the top of the crude o-chlorophenol tower, and crude p-chlorophenol is extracted from the bottom of the tower; the crude o-chlorophenol extracted here contains more than 90% o-chlorophenol and a small amount of phenol; the p-chlorophenol in the extracted material here is more than 80%;

[0009] Step ② distillation of o-chlorophenol

[0010] The crude o-chlorophenol extracted in step ① is sent to an o-chlorophenol distillation tower for heating and pressure distillation, and the finished o-chlorophenol is extracted from the top of the o-chlorophenol distillation tower, and the mixed phenol is extracted from the bottom of the tower; the o-chlorophenol content of the finished product extracted here is greater than or equal to 99.5%, and it also contains a trace amount of phenol. The mixed phenol extracted here contains more than 70% phenol, and the rest is o-chlorophenol and tar;

[0011] Step 3: distillation of p-chlorophenol

[0012] The crude para-chlorophenol extracted from the bottom of the crude o-chlorophenol tower in step ① is sent to a para-chlorophenol distillation tower for heating and pressure distillation, and mixed phenol is extracted from the top of the para-chlorophenol distillation tower, and crude para-chlorophenol is extracted from the bottom of the tower; the mixed phenol extracted here contains o-chlorophenol, phenol, 2,6-dichlorophenol, 2,4-dichlorophenol, and para-chlorophenol, wherein the content of para-chlorophenol is less than or equal to 30%; the content of para-chlorophenol in the crude para-chlorophenol extracted here is greater than or equal to 99.5%, and the rest is 2,6-dichlorophenol, 2,4,6-trichlorophenol, and tar;

[0013] Step ④ p-chlorophenol refining

[0014] In step ③, the crude p-chlorophenol extracted from the bottom of the p-chlorophenol distillation tower is sent to a p-chlorophenol refining tower for heating and pressure refining, the mixed phenol is extracted from the top of the tower, the finished p-chlorophenol is extracted from the upper side line, and the bottoms are discharged regularly; the p-chlorophenol content of the finished product extracted here is greater than or equal to 99%, and it also contains trace amounts of phenol and 2,6-dichlorophenol, and tar is removed by refining; the mixed phenol here contains phenol, p-chlorophenol, and 2,6-dichlorophenol, wherein the phenol content is greater than or equal to 60%; the main component of the bottoms is tar, containing a small amount of p-chlorophenol.

[0015] The crude o-chlorophenol tower, o-chlorophenol distillation tower, p-chlorophenol distillation tower and p-chlorophenol refining tower are sequentially connected in sequence according to the above steps ①②③④, and the above steps ①②③④ are continuously performed.

[0016] Preferably, the mixed liquid of the reaction of phenol and chlorine in step ① contains the following material components by weight: 5-8 parts by weight of phenol, 30-35 parts by weight of o-chlorophenol, 53-60 parts by weight of p-chlorophenol, 1.0-4.0 parts by weight of 2,4-dichlorophenol, 0.1-0.3 parts by weight of 2,6-dichlorophenol, and 0.19-0.4 parts by weight of tar.

[0017] Preferably, the control conditions of the crude o-chlorophenol tower are: tower top pressure 2-4 KPa, tower bottom pressure 1-4 KPa higher than the tower top, tower top temperature 60-80°C, and tower bottom temperature 110-130°C.

[0018] Preferably, the control conditions of the o-chlorophenol distillation tower are: tower top pressure 2-4 KPa, tower bottom pressure 1-4 KPa higher than the tower top, tower top temperature 60-80°C, and tower bottom temperature 110-130°C.

[0019] Preferably, the control conditions of the p-chlorophenol distillation tower are: tower top pressure 2-4 KPa, tower bottom pressure 1-4 KPa higher than the tower top, tower top temperature 80-110°C, and tower bottom temperature 120-140°C.

[0020] Preferably, the control conditions of the p-chlorophenol refining tower are: tower top pressure 2-4KPa, tower bottom pressure 1-4KPa higher than the tower top, tower top temperature 110-140°C, and tower bottom temperature 120-150°C.

[0021] Preferably, the speed at which the mixed liquid described in step ① is fed into the crude o-chlorophenol tower is 1300-1700 Kg / h.

[0022] Preferably, the reboilers of the crude o-chlorophenol tower, o-chlorophenol distillation tower, p-chlorophenol distillation tower and p-chlorophenol refining tower are all vertical tube-and-shell thermosyphon heat exchangers, which have high thermal efficiency and are energy-saving.

[0023] Preferably, the controlled reflux ratio of the crude o-chlorophenol tower is 1.7-1.8, the controlled reflux ratio of the o-chlorophenol distillation tower is 1.0-1.1, the controlled reflux ratio of the p-chlorophenol distillation tower is 2.0-2.1, and the controlled reflux ratio of the p-chlorophenol refining tower is 2.0-2.2.

[0024] Preferably, the mixed phenol extracted in step ② or ④ is returned to the mixed liquid prepared in step ①. Since the phenol content in the mixed phenol at these two places is high, it can be used as a raw material for the reaction of phenol and chlorine, realizing the recycling of materials.

[0025] The beneficial effects of the present invention are as follows: in the method for separating o-chlorophenol / p-chlorophenol from phenol chlorinated liquid, steps ①②③④ are performed continuously, materials flow continuously, residence time is short, production efficiency is greatly improved, energy consumption is reduced, the thermal sensitivity problem of p-chlorophenol being converted into tar is reduced, and the quality stability of the output product is improved.

[0026] 1. The reboiler of the distillation tower in this process adopts a vertical tube thermosyphon heat exchanger, which occupies a small area and requires less investment compared to the horizontal distillation kettle used for heating in intermittent distillation;

[0027] 2. This process uses continuous distillation separation, which increases the production capacity by 40% compared with intermittent distillation;

[0028] 3. This process uses continuous distillation separation, which has a shorter residence time than batch distillation, and the thermal sensitivity of chlorophenol to tar is reduced;

[0029] 4. This process uses continuous distillation separation, and the product quality is more stable than that of intermittent distillation;

[0030] 5. This process uses continuous distillation separation, which requires fewer people than intermittent distillation and is conducive to automated operation;

[0031] 6. This process uses continuous distillation separation, which reduces energy consumption by 30% compared to intermittent distillation. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 The present invention is a process diagram of the method for separating o-chlorophenol and p-chlorophenol in phenol chlorination liquid. DETAILED DESCRIPTION

[0033] Example 1: See Figure 1 , a method for separating o-chlorophenol / p-chlorophenol in phenol chlorination liquid, comprising the following steps:

[0034] Step 1

[0035] The mixed liquid after the reaction of phenol and chlorine is sent to the crude o-chlorophenol tower for separation at a speed of 1300Kg / h. The mixed liquid contains the following material components by weight: 6.6 parts by weight of phenol, 34.07 parts by weight of o-chlorophenol, 55.1 parts by weight of p-chlorophenol, 0.23 parts by weight of 2,6-dichlorophenol, 3.6 parts by weight of 2,4-dichlorophenol, and 0.4 parts by weight of tar. The operating parameters of the crude o-chlorophenol tower are: the top pressure / temperature is 2.8Kpa / 66°C, the bottom pressure / temperature is 4.63Kpa / 122°C, and the reflux ratio is controlled to be 1.8. The crude o-chlorophenol is extracted from the top of the crude o-chlorophenol tower, and the o-chlorophenol content is 94.15% and the phenol content is 5.85%, and it is sent to the o-chlorophenol distillation tower. The crude p-chlorophenol is extracted from the bottom of the crude o-chlorophenol tower and enters the p-chlorophenol distillation tower.

[0036] Step 2

[0037] The top of the o-chlorophenol distillation tower produces finished o-chlorophenol to the receiving tank, where the o-chlorophenol content is 99.92% and the phenol content is 0.08%. The bottom of the tower produces mixed phenol and sends it to the mixed phenol storage tank, where the o-chlorophenol content is 13.25%, the phenol content is 86.72%, and the tar content is 0.03%. The operating parameters of the o-chlorophenol tower are: the top pressure / temperature are 2.83Kpa / 72.3℃, the bottom pressure / temperature are 3.98Kpa / 112℃, and the reflux ratio is controlled at 1.0.

[0038] Step 3

[0039] The top of the p-chlorophenol distillation tower produces mixed phenol, and the content of o-chlorophenol is 2.39%, phenol is 42.75%, 2,6-dichlorophenol is 1.57%, 2,4-dichlorophenol is 29.1%, and p-chlorophenol is 24.19%. The crude p-chlorophenol produced at the bottom is sent to the p-chlorophenol refining tower, and the content of p-chlorophenol is 99.86%, 2,6-dichlorophenol is 0.09%, 2,4,6-trichlorophenol is 0.02%, and tar is 0.03%. The operating parameters of the p-chlorophenol distillation tower are: the top pressure / temperature are 3.0Kpa / 88.3℃, the bottom pressure / temperature are 4.25Kpa / 138℃, and the reflux ratio is controlled at 2.0.

[0040] Step 4

[0041] The top of the p-chlorophenol refining tower produces a phenol-rich mixed phenol to a receiving tank, where the phenol content is 61.8%, p-chlorophenol 37.8%, and 2,6-dichlorophenol 0.4%. The finished p-chlorophenol is produced from the upper side line, where the p-chlorophenol content is 99.88%, phenol 0.08%, and 2,6-dichlorophenol 0.04%. Tar is discharged intermittently at the bottom. The operating parameters of the p-chlorophenol refining tower are: the top pressure / temperature are 2.0Kpa / 120.3℃, the bottom pressure / temperature are 4.25Kpa / 142℃, and the reflux ratio is controlled at 2.0.

[0042] The reboilers of the crude o-chlorophenol tower, o-chlorophenol distillation tower, p-chlorophenol distillation tower and p-chlorophenol refining tower are all vertical tube-in-tube thermosyphon heat exchangers with high thermal efficiency and energy saving.

[0043] Example 2: See Figure 1 A method for separating o-chlorophenol and p-chlorophenol from phenol chlorination liquid comprises the following steps: step ①

[0044] The mixed liquid after the reaction of phenol and chlorine is sent to the crude o-chlorophenol tower for separation at a speed of 1700Kg / h. The mixed liquid contains the following material components by weight: 6.1 parts by weight of phenol, 33.1 parts by weight of o-chlorophenol, 57.1 parts by weight of p-chlorophenol, 0.21 parts by weight of 2,6-dichlorophenol, 3.3 parts by weight of 2,4-dichlorophenol, and 0.19 parts by weight of tar. The operating parameters of the crude o-chlorophenol tower: the top pressure / temperature are 2.6Kpa / 60℃, the bottom pressure / temperature are 3.60Kpa / 118℃, and the reflux ratio is controlled to be 1.7. The crude o-chlorophenol is extracted from the top of the crude o-chlorophenol tower, wherein the o-chlorophenol content is 95.22% and the phenol content is 4.78%, and it is sent to the o-chlorophenol distillation tower. The crude p-chlorophenol is extracted from the bottom of the o-chlorophenol tower and enters the p-chlorophenol distillation tower.

[0045] Step 2

[0046] The top of the o-chlorophenol distillation tower produces finished o-chlorophenol to a receiving tank, where the o-chlorophenol content is 99.98% and the phenol content is 0.02%. The bottom produces mixed phenol to a mixed phenol storage tank, where the o-chlorophenol content is 14.10%, the phenol content is 85.87%, and the tar content is 0.03%. The operating parameters of the o-chlorophenol tower are: the top pressure / temperature are 2.78Kpa / 68.3℃, the bottom pressure / temperature are 3.92Kpa / 109℃, and the reflux ratio is controlled at 1.1.

[0047] Step 3

[0048] The top of the p-chlorophenol distillation tower produces mixed phenol, which contains 2.44% o-chlorophenol, 43.22% phenol, 1.41% 2,6-dichlorophenol, 29.03% 2,4-dichlorophenol and 23.90% p-chlorophenol. The bottom produces crude p-chlorophenol and sends it to the p-chlorophenol refining tower, which contains 99.87% p-chlorophenol, 0.09% 2,6-dichlorophenol, 0.02% 2,4,6-trichlorophenol and 0.02% tar. The operating parameters of the p-chlorophenol distillation tower are: the top pressure / temperature are 2.8Kpa / 85.3℃, the bottom pressure / temperature are 4.4Kpa / 135℃, and the reflux ratio is controlled at 2.1.

[0049] Step 4

[0050] The top of the p-chlorophenol refining tower produces a phenol-rich mixed phenol to a receiving tank, where the phenol content is 65.8%, p-chlorophenol is 33.8%, and 2,6-dichlorophenol is 0.4%. The upper side line produces finished p-chlorophenol, where the p-chlorophenol content is 99.90%, phenol is 0.06%, and 2,6-dichlorophenol is 0.04%. Tar is discharged intermittently at the bottom. The operating parameters of the p-chlorophenol refining tower are: the top pressure / temperature are 2.1Kpa / 122.3℃, the bottom pressure / temperature are 4.35Kpa / 144℃, and the reflux ratio is controlled at 2.2.

[0051] The reboilers of the crude o-chlorophenol tower, o-chlorophenol rectifying tower, p-chlorophenol rectifying tower and p-chlorophenol refining tower are all vertical tube-and-tube thermosyphon heat exchangers, which have high thermal efficiency and are energy-saving. The mixed phenol extracted in step ② or ④ described in the above-mentioned embodiment 1 and 2 is returned to the mixed liquid prepared in step ①. Since the phenol content in the mixed phenol at these two places is high, it can be used as a raw material for the reaction of phenol and chlorine, realizing the recycling of materials, reducing waste and saving raw materials, so that a further optimized embodiment can be formed.

Claims

1. A method for separating o-chlorophenol and p-chlorophenol from phenol chlorination liquid, comprising the following steps: Step ① Crude separation of o- / p-chlorophenol The mixed liquid after the reaction of phenol and chlorine is sent to a crude o-chlorophenol tower for heating and pressurization separation, and crude o-chlorophenol is extracted from the top of the crude o-chlorophenol tower, and crude p-chlorophenol is extracted from the bottom of the tower; Step ② Distillation of o-chlorophenol The crude o-chlorophenol extracted in step ① is sent to an o-chlorophenol distillation tower for heating and pressure distillation, and the finished o-chlorophenol is extracted from the top of the o-chlorophenol distillation tower, and the mixed phenol is extracted from the bottom of the tower; Step 3: Distillation of p-chlorophenol The crude p-chlorophenol extracted from the bottom of the crude o-chlorophenol tower in step ① is sent to a p-chlorophenol distillation tower for heating and pressure distillation, and mixed phenol is extracted from the top of the p-chlorophenol distillation tower, and crude p-chlorophenol is extracted from the bottom of the tower; Step ④ Purification of p-chlorophenol In step ③, the crude p-chlorophenol extracted from the bottom of the p-chlorophenol distillation tower is sent to a p-chlorophenol refining tower for heating and pressure refining, mixed phenol is extracted from the top of the tower, finished p-chlorophenol is extracted from the upper side line, and the bottoms are discharged regularly; The crude o-chlorophenol tower, o-chlorophenol distillation tower, p-chlorophenol distillation tower and p-chlorophenol refining tower are sequentially connected in sequence according to the above steps ①②③④, and the above steps ①②③④ are continuously performed.

2. A method for separating o- / p-chlorophenol in a chlorinated phenol solution according to claim 1, characterized in that: The mixed liquid of the reaction of phenol and chlorine in step ① contains the following material components by weight: 5-8 parts by weight of phenol, 30-35 parts by weight of o-chlorophenol, 53-60 parts by weight of p-chlorophenol, 1.0-4.0 parts by weight of 2,4-dichlorophenol, 0.1-0.3 parts by weight of 2,6-dichlorophenol, and 0.19-0.4 parts by weight of tar.

3. A method for separating o- / p-chlorophenol in a chlorinated phenol solution according to claim 1, characterized in that: The control conditions of the crude o-chlorophenol tower are: tower top pressure 2-4Kpa, tower bottom pressure 1-4Kpa higher than the tower top, tower top temperature 60-80°C, and tower bottom temperature 110-130°C.

4. A method for separating o- / p-chlorophenol in a chlorinated phenol solution according to claim 3, characterized in that: The control conditions of the o-chlorophenol distillation tower are: tower top pressure 2-4Kpa, tower bottom pressure 1-4Kpa higher than the tower top, tower top temperature 60-80°C, and tower bottom temperature 110-130°C.

5. A method for separating o- / p-chlorophenol in a chlorinated phenol solution according to claim 4, characterized in that: The control conditions of the p-chlorophenol distillation tower are: tower top pressure 2-4Kpa, tower bottom pressure 1-4Kpa higher than the tower top, tower top temperature 80-110°C, and tower bottom temperature 120-140°C.

6. A method for separating o-chlorophenol and p-chlorophenol in a chlorinated phenol solution according to claim 5, characterized in that: The control conditions of the p-chlorophenol refining tower are: tower top pressure 2-4Kpa, tower bottom pressure 1-4Kpa higher than tower top, tower top temperature 110-140°C, and tower bottom temperature 120-150°C.

7. A method for separating o-chlorophenol and p-chlorophenol in chlorinated phenol solution 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 1300 ~ 1700 Kg / h.

8. A method for separating o-chlorophenol and p-chlorophenol in chlorinated phenol solution according to claim 1, characterized in that: The reboilers of the crude o-chlorophenol tower, o-chlorophenol distillation tower, p-chlorophenol distillation tower and p-chlorophenol refining tower are all vertical tube-and-shell thermosyphon heat exchangers.

9. A method for separating o-chlorophenol and p-chlorophenol in chlorinated phenol solution according to claim 8, characterized in that: The controlled reflux ratio of the crude o-chlorophenol tower is 1.7-1.8, the controlled reflux ratio of the o-chlorophenol distillation tower is 1.0-1.1, the controlled reflux ratio of the p-chlorophenol distillation tower is 2.0-2.1, and the controlled reflux ratio of the p-chlorophenol refining tower is 2.0-2.

2.

10. A method for separating o-chlorophenol and p-chlorophenol in chlorinated phenol solution according to claim 1, characterized in that: The mixed phenol extracted in step ② or ④ is returned to the mixed liquid prepared in step ①.

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