CN1180066A - Chloroacetic acid producing process - Google Patents
Chloroacetic acid producing process Download PDFInfo
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- CN1180066A CN1180066A CN 96109887 CN96109887A CN1180066A CN 1180066 A CN1180066 A CN 1180066A CN 96109887 CN96109887 CN 96109887 CN 96109887 A CN96109887 A CN 96109887A CN 1180066 A CN1180066 A CN 1180066A
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Abstract
The present invention relates to a new technological process for producing organic chemical raw material chloroacetic acid. Said new process optimizes the technological conditions and equipment of existent generally-adopted acetic acid chlorination method, and under the condition of dasically no changing technological process and equipment makes the purity of chloroacetic acid raised to above 98%, content of dichloroacetic acid reduced to below 1%, acetic acid consumption can be up to about 680 kg/t, chlorine gas consumption can be up to about 810 kg/t, and the chloroacetic acid content in the chlorinated liquor can be up to 95-97%, and for production of agricultural pesticides of omethoate and dimethoate, it has no need of crystallization, and can be directly used after esterification. Said invention possesses the advantages of simple process, easy operation, high product quality, low consumption and strong practicality, etc..
Description
The invention belongs to an organic chemical raw material.
The present invention is a new technology for producing chloroacetic acid. The product is an important intermediate of organophosphorus pesticide, and is also an important raw material for producing CMC (carboxymethyl cellulose) and glycine. It has a chemical structural formula as follows:
at present, more than 100 manufacturers for producing chloroacetic acid in China produce about 10 million tons every year, and the currently generally adopted production method is an acetic acid chlorination method. It takes acetic acid as raw material, and the general reaction formula is as follows:
sulfur powder
The reaction process of the sulfur powder as the catalyst is as follows:
1、
2、
3、
4、
possible side reactions are:
1、
2、 from the above catalytic reaction scheme, it can be seen that: the catalytic active intermediate of the chlorination reaction is acetyl chloride, so the concentration of the acetyl chloride during the chlorination reaction directly influences the chlorination reaction speed and the generation of the byproduct, namely the dichloroacetic acid. The production process of chloroacetic acid adopted at present is as follows:
respectively adding the same amount of acetic acid and sulfur powder with the amount of 2.5 percent acetic acid into a main chlorination reaction kettle and a secondary chlorination reaction kettle which are provided with a straight chlorine pipe, and starting heating after the two kettles are completely charged; when the temperature of the main kettle reaches 95 ℃ and the temperature of the auxiliary kettle reaches 75 ℃, chlorine is slowly introduced into the main kettle for chlorination, a large amount of hydrogen chloride gas generated by the reaction carries unreacted chlorine and generated low-boiling-point substances such as acetyl chloride and the like through the water-cooled condenser, the hydrogen chloride carries the chlorine and the uncondensed low-boiling-point substances such as acetyl chloride and the like into the auxiliary kettle, the chlorine continuously reacts with acetic acid, the condensed low-boiling-point substances such as acetyl chloride and the like return to the main kettle, the temperature of the main kettle and the auxiliary kettle can continuously rise along with the continuous introduction of the chlorine, the temperature of the main kettle is maintained at 100 +/-2 ℃ and the temperature of the auxiliary kettle is maintained at 80 +/-2 ℃ in the chlorine introducing process, and the chlorination reaction is immediately stopped when the specific gravity of the chlorination liquid in the main kettle reaches 1.35/80 ℃, so that the chlorination reaction is finished. After chlorination reaction, pumping chlorination liquid in a main kettle into a crystallization kettle, adding a proper amount of chloroacetic acid mother liquor, slowly cooling the chlorination liquid to crystallize under stirring, when the temperature of crystals is reduced to 28-30 ℃, indicating that crystallization is finished, then placing a mixture of crystals and the mother liquor into a suction filtration barrel, and separating the crystals and the mother liquor by vacuum suction filtration to obtain a chloroacetic acid crystal product. The method needs to consume more than 750Kg of acetic acid and more than 1000Kg of chlorine per ton of chloroacetic acid crystal products, and the purity of the chloroacetic acid crystal products is below 96 percent.
In recent years, some technical data and patents (CN 1031563C) report improvement of chloroacetic acid production, which aims to reduce the loss of acetyl chloride, inhibit the generation of dichloroacetic acid as a byproduct and reduce the consumption of raw materials. If the method is adopted for production, 714Kg of acetic acid is consumed by each ton of chloroacetic acid crystal products, which is reported, and compared with the currently generally adopted production process, the consumption of the acetic acid is reduced by 30-80 Kg/t. The specific improved scheme is as follows: 1. the amount of the sulfur powder of the catalyst is about 1 percent of the amount of the acetic acid; 2. when the temperaturereaches 70 ℃, chlorine is slowly introduced into the main kettle for chlorination, a large amount of hydrogen chloride gas generated by the reaction carries unreacted chlorine and generated low-boiling-point substances such as acetyl chloride and the like to pass through a frozen brine condenser below-15 ℃, the hydrogen chloride carries the chlorine to enter a subsidiary kettle, the chlorine continuously reacts with acetic acid, the condensed acetyl chloride returns to the main kettle, the initial chlorine introduction amount is 20-25 Kg/h, the middle chlorine introduction amount is 35-40 Kg/h, the later chlorine introduction amount is 20-25 Kg/h, the final chlorination temperature reaches 98 +/-2 ℃, and the temperature of the subsidiary kettle is kept constant at about 70 ℃; 3. when the specific weight of the chlorinated liquid in the main kettle reaches 1.21-1.24/80 ℃, closing the frozen brine to distill low-boiling-point substances such as acetyl chloride and the like in the main kettle, and when the specific weight of the chlorinated liquid in the main kettle reaches 1.32/80 ℃, further distilling substances in the reaction kettle through a short-cut distillation tube (a distillation tube which does not pass through a main kettle condenser) arranged on the main kettle; 4. when the specific weight of the chlorination liquid in the main kettle reaches 1.35/80 ℃, stopping introducing chlorine, and introducing nitrogen for 10-20 minutes.
Through the deep understanding and investigation of the existing acetic acid chlorination production process, a large number of industrial tests and dynamic tracking analysis show that:
1. the chlorination reaction system is a solid-liquid-gas heterogeneous reaction system, and the general production process and the method reported by the patent have the phenomena of uneven distribution and local over-concentration of chlorine gas, so that the byproduct dichloroacetic acid is increased, the chlorine gas is incompletely reacted, the consumption of the chlorine gas and the acetic acid is increased, and the chlorine introducing time is prolonged.
2. The chlorine introducing temperature of the general production process is too high, and the chlorine introducing speed is too low, namely the chlorine introducing time is too long in the method reported by the patent, so that the dichloroacetic acid by-product is increased.
3. In the chlorination reaction process, the generated active intermediate acetyl chloride has a low boiling point (about 51 ℃) and is easy to volatilize, and a large amount of hydrogen chloride gas generated in the chlorination reaction can carry materials, for example, according to the production situation, only a water-cooled condenser or only a single-stage frozen brine condenser or only a frozen brine condenser with insufficient cooling area is adopted on a reaction kettle, so that the condensation effect of the whole system is poor, low-boiling-point substances such as the active intermediate acetyl chloride and the like cannot be condensed and returned to the chlorination kettle in time, the loss of the acetyl chloride is caused, if sulfur powder is not supplemented in time, the catalytic reaction activity is reduced, the consumption of chlorine and acetic acid is increased, the chlorine passing time is prolonged, and the dichloroacetic acid byproduct is increased.
4. The general production process has high sulfur powder consumption, increases chloroacetyl chloride in the chlorination reaction process and promotes the generation of dichloroacetic acid as a byproduct. The patent reports that the sulfur powder is less in amount, which is advantageous for inhibiting the formation of dichloroacetic acid as a by-product in the initial stage, but the chlorination reaction is slow in the later stage, the chlorine introducing time is prolonged, and the formation of dichloroacetic acid as a by-product is promoted.
5. As reported in the above patent, when the specific gravity of the chlorinated solution is about 1.20/80 ℃, low boiling point substances such as acetyl chloride are distilled out, so that the concentration of acetyl chloride is reduced, the catalytic reaction activity is greatly reduced, the late chlorination reaction is not facilitated, the consumption of chlorine and acetic acid is increased, the chlorination reaction time is prolonged, and the by-product dichloroacetic acid is increased, which is obviously not preferable.
6. The crystallization method of the chlorination liquid comprises the following steps: at present, a one-step cooling crystallization method is generally adopted, and the chloroacetic acid crystal obtained by the method has small particles and poor appearance.
7. Isolated form of the crystals from the mother liquor: at present, vacuum pump suction filtration is generally adopted, and if the vacuum degree of a system is low or the position of an exhaust tube under a suction filtration cylinder is not properly installed, the mother liquor is not separated completely, and the purity of chloroacetic acid is influenced. Moreover, the separation time is long, so that the chloroacetic acid mother liquor is increased.
These factors are most dependent not only on the purity of the chloroacetic acid and the appearance of the crystals, but also increase the consumption of acetic acid and chlorine.
On the basis of summarizing the defects of the existing acetic chlorination production process, the invention not only provides a scheme for optimizing chlorination reaction process conditions, equipment pipelines and the like, but also provides a scheme for optimizing a crystallization method and a separation form of the acetic chlorination reaction process. And invents a new process for improving the purity of chloroacetic acid, reducing the content of dichloroacetic acid and reducing the consumption of raw materials.
The invention has the following processes and devices for modifying the steps of chlorination, crystallization, separation and the like in the production process of the chloroacetic acid:
firstly, chlorination reaction:
1. the form of a chlorine distributor is changed, and the phenomena of uneven distribution and local over-concentration of chlorine in the chlorination reaction are overcome.
2. In order to make up for the loss caused by a large amount of hydrogen chloride gas carrying acetyl chloride and overcome the increase of dichloroacetic acid as a byproduct caused by too much sulfur powder in the initial stage, the catalyst sulfur powder is added in a small amount for a plurality of times in the chlorination reaction process, so that the proper concentration and catalytic activity of the acetyl chloride can be ensured, and the total amount of the sulfur powder can be reduced.
3. The temperature of chlorination reaction in the main kettle and the auxiliary kettle is reduced, the chlorine introducing speed is accelerated as much as possible, the chlorination reaction time is shortened, and the generation of dichloroacetic acid as a byproduct is reduced.
4. The main kettle and the auxiliary kettle are respectively provided with a water-cooled condenser and a frozen salt water-cooled condenser with enough condensation areas so as to strengthen the condensation effect of the system, reduce the loss of acetyl chloride and reduce the consumption of chlorine and acetic acid.
II, crystallization:
the product quality can be improved by adopting a crystallization method of cooling, heating and cooling again or a natural crystallization method without adding mother liquor.
Thirdly, separation:
1. changing the separation form of the crystal and the mother liquor;
2. the leaching and re-separation process of the primary crystals is added.
The optimization process of the specific operation of each step of the invention is as follows:
a: chlorination reaction:
the chlorination reaction is carried out by respectively adding acetic acid with the same amount and sulfur powder with 0.5% -2% acetic acid amount according to different conditions into a main kettle and a subsidiary kettle of a multi-hole multi-tube gas distributor (shown in attached figure) provided with similar outdoor antennas, heating when the materials are added into the two kettles, quickly introducing chlorine into the main kettle for chlorination when the temperature of the main kettle reaches 85 ℃ and the temperature of the subsidiary kettle reaches 65 ℃, condensing low-boiling-point substances such as unreacted chlorine and generated acetyl chloride carried by a large amount of hydrogen chloride gas generated by reaction by a water-cooled condenser, thoroughly condensing the uncondensed low-boiling-point substances such as acetyl chloride and the like by a large-area frozen brine condenser, respectively returning the secondary condensate into the main kettle, and feeding the chlorine carried by the hydrogen chloride into the subsidiary kettle, and continuously reacting the chlorine and the acetic acid. The chlorine introducing speed is as fast as possible on the basis of ensuring that the chlorination reaction temperature of the main kettle is maintained at 90 +/-5 ℃ and no obvious yellow chlorine gas escapes from the main gas pipe. The temperature of the main kettle and theauxiliary kettle is continuously increased along with the continuous introduction of the chlorine gas, the temperature of the main kettle is maintained at 90 +/-5 ℃, the temperature of the auxiliary kettle is maintained at 70 +/-5 ℃, and the chlorine introduction is stopped until the specific gravity of the chlorination liquid reaches 1.35/80 ℃.
B: crystallization of
a. Pumping the chlorination liquid at about 80 ℃ into a crystallization kettle, adding a proper amount of chloroacetic acid mother liquor, cooling the chlorination liquid at the highest stirring speed, slowing the stirring speed when the chlorination liquid is cooled to the temperature of about 48 ℃, preserving the heat for 2-3 hours, cooling to 30 ℃, heating the crystal to 45 ℃, preserving the heat for a period of time to melt a part of small-particle crystals, and finally cooling to 25-28 ℃, thus obtaining the material. And finishing the whole process of cooling, heating, cooling again and crystallizing.
b. Or a natural crystallization method without adding mother liquor, namely, the chlorination liquid is naturally cooled to room temperature.
C: separation of
a. The separation form of the crystal and the mother liquor adopts a centrifuge for spin-drying, so that the mother liquor in the crystallization mixed liquor can be removed more thoroughly than that by using a vacuum filtration method, and the purity of the product can be improved. The mother liquor after spin-drying separation is used as the crystallization mother liquor of the next batch, or is used as the reaction raw material of the next batch, or is directly esterified and fractionated.
b. And (3) leaching the chloroacetic acid crystals after spin-drying separation by using 0.5-2% acetic acid of the crystals if the purity requirement is high, and then performing centrifugal spin-drying to obtain a mother solution which can be used as a next batch of reaction raw materials.
The invention comprehensively optimizes various process conditions and equipment for producing chloroacetic acid by an acetic chlorination method, improves the purity of the chloroacetic acid to more than 98 percent, reduces the content of dichloroacetic acid to less than 1 percent, reduces the acetic acid consumption to about 680Kg/t and the chlorine gas consumption to about 810Kg/t under the conditions of basically not changing production raw materials and not greatly moving process equipment, can produce products (such as omethoate, dimethoate and the like) with lower purity requirement on the chloroacetic acid, can simplify the operation, namely does not need crystallization or esterification fractionation, and can be directly used after the chlorination liquid is esterified. The invention has the advantages of simple and easy operation, high product quality, low consumption, strong practicability, small investment, quick effect, high profit and the like, and can improve the capacity of earning foreign exchange in product export.
Several industrial experimental examples and comparative examples for optimizing process conditions and equipment are given below.
[ Industrial example 1]
1. 25Kmol of acetic acid and 25Kg of sulfur powder in a main kettle and 15Kg of sulfur powder in a sub kettle are respectively and sequentially added into the main kettle and the sub kettle of a multi-hole multi-tube gas distributor similar to an outdoor antenna, then the two kettles are heated simultaneously, when the temperature of the main kettle reaches 85 ℃ and the temperature of the sub kettle reaches 65 ℃, chlorine is rapidly introduced into the main kettle for chlorination, and the chlorine introducing speed is as fast as possible on the basis of ensuring that the chlorination reaction temperature of the main kettle is maintained at 90 +/-5 ℃ and no obvious yellow chlorine is escaped from a main gas tube. And (3) gradually raising the temperature of the main kettle and the auxiliary kettle along with the continuous introduction of the chlorine, maintaining the temperature of the main kettle at 90 +/-5 ℃ and the temperature of the auxiliary kettle at 70 +/-5 ℃ until the specific gravity of the chlorination liquid reaches 1.35/80 ℃, indicating that the reaction is at the end point, and immediately stopping the introduction of the chlorine to obtain the chlorination liquid. At this time, the chloroacetic acid content in the chlorination solution reaches 95.31%.
2. Pumping the chlorination liquid in the main kettle into a crystallization kettle, adding 800Kg of chloroethylene, cooling the chlorination liquid at the fastest stirring speed, changing the stirring speed to 30 rpm when the chlorination liquid is cooled to 48-50 ℃, preserving heat for 3 hours, cooling the chlorination liquid to 30 ℃, heating the crystal to 45 ℃, preserving heat for 0.5 hour, finally cooling the chlorination liquid to 28 ℃, and discharging the chlorination liquid to obtain the mixed liquid of the crystal and the mother liquid.
3. And (3) spin-drying the mixed solution by using a centrifugal machine to obtain chloroacetic acid crystals, wherein the purity of the product is 98.35%, and the content of dichloroacetic acid is 0.80%. The chloroacetic acid crystals are leached by acetic acid with the crystal amount of 1 percent, and then are dried by spinning, the purity of the obtained chloroacetic acid is 98.46 percent, and the content of dichloroacetic acid is 0.53 percent.
690Kg of acetic acid and 810Kg of chlorine are consumed for each ton of chloroacetic acid crystal products.
[Industrial example 2]
1. Pumping the sub-kettle mixed liquid generated in the industrial example 1 into the main chlorination kettle, supplementing 5Kg of sulfur powder, adding 25Kmol acetic acid and 10Kg of sulfur powder into the sub-kettle, heating the two kettles simultaneously after the feeding is finished, and introducing chlorine gas into the main kettle for chlorination when the temperature of the main kettle reaches 85 ℃ and the temperature of the sub-kettle reaches 65 ℃, wherein the chlorine introducing speed is as fast as possible on the basis of ensuring that the chlorination reaction temperature of the main kettle is maintained at 90 +/-5 ℃ and no obvious yellow chlorine gas escapes from a main gas pipe. And (3) gradually increasing the temperature of the main kettle and the auxiliary kettle along with the continuous introduction of chlorine, maintaining the temperature of the main kettle at 90 +/-5 ℃ and the temperature of the auxiliary kettle at 70 +/-5 ℃ until the specific gravity of the chlorination liquid reaches 1.35/80 ℃, indicating that the reaction reaches the end point, immediately stopping chlorine introduction, and obtaining the chlorination liquid, wherein the chloroacetic acid content in the chlorination liquid reaches 95.68%.
2. And naturally cooling the chlorination liquid in the main kettle to room temperature without adding mother liquid to obtain a mixed liquid of the crystal and the mother liquid.
3. And (3) spin-drying the mixed solution by using a centrifugal machine to obtain chloroacetic acid crystals, wherein the purity of the product is 98.37%, and the content of dichloroacetic acid is 0.93%.
685Kg of acetic acid and 800Kg of chlorine are consumed for each ton of chloroacetic acid crystal products.
[ Industrial example 3]
1. Pumping the secondary kettle mixed liquid generated in the industrial embodiment 2 into the chlorination main kettle, supplementing 3Kg of sulfur powder, adding 25Kmol acetic acid and 8Kg of sulfur powder into the secondary kettle, heating the two kettles simultaneously after the feeding is finished, and introducing chlorine gas into the main kettle for chlorination when the temperature of the main kettle reaches 85 ℃ and the temperature of the secondary kettle reaches 65 ℃, wherein the chlorine introducing speed is better on the basis of ensuring that the chlorination reaction temperature of the main kettle is maintained at 90 +/-5 ℃ and no obvious yellow chlorine gas escapes from a main gas pipe. When the chlorination reaction does not reach the end point and a large amount of yellow chlorine escapes from the main gas pipe, 2Kg of sulfur powder is supplemented. The temperature of the main kettle and the auxiliary kettle is gradually increased along with the continuous introduction of the chlorine gas, the temperature of the main kettle is maintained at 90 +/-5 ℃, the temperature of the auxiliary kettle is maintained at 70 +/-5 ℃, when the specific gravity of the chlorination liquid reaches 1.35/80 ℃, the reaction is ended, the chlorine introduction is immediately stopped, and the chlorination liquid is obtained, wherein the chloroacetic acid content in the chlorination liquid reaches 96.18%.
2. Pumping the chlorination liquid in the main kettle into a crystallization kettle, adding 600Kg of chloroacetic acid mother liquor, cooling the chlorination liquid at the fastest stirring speed, changing the stirring speed to 30 rpm when the chlorination liquid is cooled to 48-50 ℃, preserving heat for 2 hours, cooling to 30 ℃, heating the crystal to 45 ℃, preserving heat for 1 hour, finally cooling to 28 ℃, and discharging to obtain the mixed liquid of the crystal and the mother liquor.
3. And (3) spin-drying the mixed solution by using a centrifugal machine to obtain chloroacetic acid crystals, wherein the purity of the product is 98.97%, and the content of dichloroacetic acid is 0.54%.
The consumption of acetic acid and chlorine in each ton of chloroacetic acid crystal products is 680Kg and 805 Kg.
[ Industrial example 4]
1. Pumping the secondary kettle mixed liquid generated in the industrial embodiment 3 into the main chlorination kettle, adding 4Kg of sulfur powder, adding 25Kmol acetic acid and 10Kg of sulfur powder into the secondary kettle, heating the two kettles simultaneously after the feeding is finished, and introducing chlorine gas into the main kettle when the temperature of the main kettle reaches 85 ℃ and the temperature of the secondary kettle reaches 65 ℃, wherein the chlorine introducing speed is better on the basis of ensuring that the chlorination reaction temperature of the main kettle is maintained at 90 +/-5 ℃ and no obvious yellow chlorine gas escapes from a main gas pipe. When the chlorination reaction does not reach the end point and a large amount of yellow chlorine escapes from the main gas pipe, 1Kg of sulfur powder is added, the temperature of the main kettle and the auxiliary kettle gradually rises along with the continuous introduction of the chlorine, the temperature of the main kettle and the auxiliary kettle is maintained at 90 +/-5 ℃ and 70 +/-5 ℃ until the specific gravity of the chlorination liquid reaches 1.35/80 ℃, the chlorine introduction is stopped immediately after the reaction reaches the end point, and the chlorination liquid is obtained, wherein the chloroacetic acid content in the chlorination liquid reaches 96.88%, and then the chlorination liquid is esterified and directly used for omethoate production.
If the method of non-crystallization or esterification fractionation of the chlorinated solution is adopted, 665Kg/t of acetic acid is consumed, and 795Kg/t ofchlorine is consumed.
[ Industrial comparative example 1]
1. Respectively adding 25Kmol acetic acid and 38Kg of sulfur powder into a chlorination main kettle and a chlorination auxiliary kettle which are provided with a straight pipe chlorine introducing pipe, heating the two kettles simultaneously after the charging is finished, introducing chlorine gas into the main kettle at a speed of 50-60 Kg/h for chlorination when the temperature of the main kettle reaches 95 ℃ and the temperature of the auxiliary kettle reaches 75 ℃, increasing the chlorine introducing speed to 80-100 Kg/h after 5 hours, gradually increasing the temperature of the main kettle and the auxiliary kettle along with the continuous introduction of the chlorine gas, maintaining the temperature of the main kettle to be 100 +/-2 ℃, and maintaining the temperature of the auxiliary kettle to be 80 +/-2 ℃. And (3) after chlorine is introduced for about the last 5 hours, reducing the chlorine introduction speed to 50-70 Kg/h until the specific gravity of the chlorination liquid reaches 1.35/80 ℃, indicating that the reaction reaches the end point, and immediately stopping chlorine introduction to obtain the chlorination liquid, wherein the content of chloroacetic acid in the chlorination liquid is only 89.64%.
2. Pumping the chlorination liquid in the main kettle into a crystallization kettle, adding 1000Kg of mother liquid, cooling at the stirring speed of 30 r/min, preserving heat for 5 hours when the chlorination liquid is cooled to 48-50 ℃, and finally cooling to 30 ℃ to obtain the mixed liquid of the crystal and the mother liquid.
3. And (3) discharging the mixed solution, performing suction filtration by using a vacuum pump, and obtaining chloroacetic acid crystals after the suction filtration, wherein the purity of the product is 94.17%, and the content of dichloroacetic acid is 4.85%.
780Kg of acetic acid and 1080Kg of chlorine are consumed for each ton of chloroacetic acid crystal products.
Claims (6)
1. An improved method for producing chloroacetic acid, which takes acetic acid and chlorine as raw materials to produce chloroacetic acid, and is characterized in that: respectively adding acetic acid and sulfur powder with the amount of 0.5-2% acetic acid into a main chlorination kettle and a sub-chlorination kettle of a multi-hole multi-tube gas distributor with similar outdoor antennas, when the temperature of the main chlorination kettle reaches 85 ℃ and the temperature of the sub-chlorination kettle reaches 65 ℃, quickly introducing chlorine gas into the main chlorination kettle for chlorination, condensing a large amount of hydrogen chloride gas generated by reaction with a small amount of unreacted chlorine gas and generated low-boiling substances such as acetyl chloride through a water-cooled condenser, completely condensing the uncondensed low-boiling substances such as acetyl chloride through a large-area chilled brine condenser, respectively returning the secondary condensate into the main chlorination kettle, introducing chlorine gas into the sub-chlorination kettle, continuously reacting the chlorine gas with the acetic acid, and ensuring that the chlorination reaction temperature of the main chlorination kettle is kept at 90 +/-5 ℃ and no obvious yellow chlorine gas escapes from a main gas pipe, so as to shorten the chlorine introducing time as much as possible, stopping chlorine introduction until the specific gravity of the chlorination liquid reaches 1.35/80 ℃ and the reaction reaches the end point,
2. a method according to claim 1, characterized in that: the sulfur powder as catalyst for chlorination reactionmay be added several times in small amount, and the sulfur powder is replenished after the chlorination reaction has not reached the end point and great amount of yellow chlorine gas has escaped from the main gas pipe. The catalyst can also be selected from phosphorus, acetic anhydride, acetyl chloride, phosphorus trichloride and the like.
3. A method according to claim 1, characterized in that: the crystallization method of the chlorination liquid adopts a crystallization method of firstly cooling to 48-50 ℃, preserving heat for 2-3 hours, then cooling to 30 ℃, then heating to 45 ℃, preserving heat for a period of time to melt a part of small-particle crystals, and finally cooling to 25-28 ℃.
4. A method according to claim 1, characterized in that: the crystallization method of the chlorination liquid can adopt a natural crystallization method without adding mother liquid, namely, the chlorination liquid is naturally cooled to room temperature.
5. A method according to claim 1, characterized in that: the crystal and mother liquor are separated by centrifugal drying, and the obtained mother liquor is used as next crystallization mother liquor, or next reaction raw material, or directly esterified and fractionated.
6. The method of claim 5, wherein: and (3) leaching the chloroacetic acid crystals after spin-drying separation by using 0.5-2% acetic acid of the crystals if the purity requirement is high, and then performing centrifugal spin-drying to obtain a mother solution which can be used as a next batch of reaction raw materials.
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| CN96109887A CN1059662C (en) | 1996-10-03 | 1996-10-03 | Chloroacetic acid producing process |
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| CN96109887A CN1059662C (en) | 1996-10-03 | 1996-10-03 | Chloroacetic acid producing process |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102875357A (en) * | 2012-10-11 | 2013-01-16 | 江苏省格林艾普化工股份有限公司 | Process for producing chloroactic acid by large chlorinated kettles and chlorinated kettles for reaction |
| CN101386574B (en) * | 2007-09-10 | 2013-01-23 | 张天德 | Method for preparing chloracetic acid using acetyl chloride as catalyst |
| CN102908955A (en) * | 2011-08-01 | 2013-02-06 | 中国石油化工股份有限公司 | Large-hole sieve tray esterification reactor and preparation method of dimethyl maleate |
| CN106220491A (en) * | 2016-07-29 | 2016-12-14 | 河北科技大学 | Production of chloroacetic acid method |
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| CN101844058A (en) * | 2010-06-03 | 2010-09-29 | 濮阳市普天化工有限公司 | Equipment for producing chloroacetic acid |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN1009277B (en) * | 1987-08-25 | 1990-08-22 | 吉林大学 | Production of nonantigenic high-performance antitumour drug-l-asparaginase |
| CN1033450A (en) * | 1987-12-05 | 1989-06-21 | 杜谏 | New universal handle |
| CN1027889C (en) * | 1991-01-31 | 1995-03-15 | 翟超进 | Method for preparing monochloro-acetic acid |
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| CN101386574B (en) * | 2007-09-10 | 2013-01-23 | 张天德 | Method for preparing chloracetic acid using acetyl chloride as catalyst |
| CN102908955A (en) * | 2011-08-01 | 2013-02-06 | 中国石油化工股份有限公司 | Large-hole sieve tray esterification reactor and preparation method of dimethyl maleate |
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| CN102875357A (en) * | 2012-10-11 | 2013-01-16 | 江苏省格林艾普化工股份有限公司 | Process for producing chloroactic acid by large chlorinated kettles and chlorinated kettles for reaction |
| CN102875357B (en) * | 2012-10-11 | 2014-10-15 | 江苏省格林艾普化工股份有限公司 | Process for producing chloroactic acid by large chlorinated kettles and chlorinated kettles for reaction |
| CN106220491A (en) * | 2016-07-29 | 2016-12-14 | 河北科技大学 | Production of chloroacetic acid method |
| CN106220491B (en) * | 2016-07-29 | 2018-12-11 | 河北科技大学 | Production of chloroacetic acid method |
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