CN108610261B - Synthetic method for improving yield of phenylenediamine - Google Patents
Synthetic method for improving yield of phenylenediamine Download PDFInfo
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- CN108610261B CN108610261B CN201810393439.3A CN201810393439A CN108610261B CN 108610261 B CN108610261 B CN 108610261B CN 201810393439 A CN201810393439 A CN 201810393439A CN 108610261 B CN108610261 B CN 108610261B
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C209/00—Preparation of compounds containing amino groups bound to a carbon skeleton
- C07C209/30—Preparation of compounds containing amino groups bound to a carbon skeleton by reduction of nitrogen-to-oxygen or nitrogen-to-nitrogen bonds
- C07C209/32—Preparation of compounds containing amino groups bound to a carbon skeleton by reduction of nitrogen-to-oxygen or nitrogen-to-nitrogen bonds by reduction of nitro groups
- C07C209/36—Preparation of compounds containing amino groups bound to a carbon skeleton by reduction of nitrogen-to-oxygen or nitrogen-to-nitrogen bonds by reduction of nitro groups by reduction of nitro groups bound to carbon atoms of six-membered aromatic rings in presence of hydrogen-containing gases and a catalyst
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D9/00—Crystallisation
- B01D9/0004—Crystallisation cooling by heat exchange
- B01D9/0013—Crystallisation cooling by heat exchange by indirect heat exchange
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C209/00—Preparation of compounds containing amino groups bound to a carbon skeleton
- C07C209/82—Purification; Separation; Stabilisation; Use of additives
- C07C209/84—Purification
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C209/00—Preparation of compounds containing amino groups bound to a carbon skeleton
- C07C209/82—Purification; Separation; Stabilisation; Use of additives
- C07C209/86—Separation
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D9/00—Crystallisation
- B01D2009/0086—Processes or apparatus therefor
Abstract
The invention relates to a synthetic method for improving the yield of phenylenediamine, which takes nitroaniline as a raw material and sodium sulfide as a reducing agent to carry out a reduction reaction at a high temperature so as to generate phenylenediamine solution, sodium thiosulfate solution and sodium hydroxide solution in a first reaction kettle; distilling the material in the first reaction kettle under the vacuum condition and distilling out a sodium thiosulfate solution under the vacuum condition; continuously carrying out negative pressure distillation on the residual materials in the first reaction kettle, and distilling out a phenylenediamine solution under a vacuum condition; crystallizing the p-phenylenediamine solution in a second reaction kettle to obtain a crude product of the p-phenylenediamine; and rectifying the phenylenediamine crude product in a third reaction kettle, and slicing and packaging. Wherein, the second reaction device comprises a kettle body, a kettle cover and a jacket. The synthetic method for improving the yield of phenylenediamine effectively reduces the cooling time in the crystallization process of phenylenediamine, so that the yield of phenylenediamine reaches over 90 percent.
Description
Technical Field
The invention relates to a method for synthesizing phenylenediamine, belongs to the field of fine chemical engineering, and particularly relates to a method for synthesizing phenylenediamine with improved yield.
Background
The phenylenediamine is an organic chemical intermediate with wide application, and comprises three isomers, namely m-phenylenediamine, o-phenylenediamine and p-phenylenediamine. The p-phenylenediamine can be used for preparing azo dyes and high molecular polymers, and can also be used for producing fur coloring agents, rubber anti-aging agents and photo developers, and the p-phenylenediamine is also a commonly used sensitive reagent for detecting iron and copper.
The finished p-phenylenediamine product sold in the market mainly has two states of a sheet state and a block state, and the sheet state is formed by condensing and slicing refined p-phenylenediamine after rectification. Compared with a blocky product, the flaky phenylenediamine has a small oxidized proportion in the high-temperature cooling process due to large contact area with air and high heat dissipation speed; however, during the conventional storage process, the phenylenediamine in a flake shape is easily slowly oxidized in the air so as to gradually change from white to gray and black, and the storage life of the product is influenced. Therefore, the phenylenediamine in the form of a sheet should be vented after unpackaged and used again well and used up as soon as possible. Compared with the flaky p-phenylenediamine, the blocky p-phenylenediamine product has higher density and low thermal conductivity coefficient, meanwhile, the contact area of the blocky p-phenylenediamine and air is small, and the main oxidation process is on the surface and is relatively more storage-resistant.
At present, the main production process for producing massive p-phenylenediamine in China is to use p-nitroaniline as a raw material and obtain the massive p-phenylenediamine by reducing sodium sulfide. The existing process method has the following defects: the product has low yield which is less than 80%; a large amount of sulfide-containing red water is generated after the reduction reaction, and the pollution to the environment is serious; the reaction solution is difficult to adopt a rectification method, and the yield is low. The existing reaction kettle has the following disadvantages: the traditional cooling method generally adopts a crystallization kettle with a larger volume, and the crystallization kettle is cooled by introducing low-temperature and saturated salt solution (cooling liquid) into an outer jacket, but as massive phenylenediamine is only contacted with air on the surface, the phenylenediamine has high density and poor heat conductivity, the temperature reduction speed of the center of the phenylenediamine liquid is extremely low, the center part of the phenylenediamine liquid is easy to oxidize and blacken, and the difficulty of screening good products is increased while the yield of the phenylenediamine is reduced.
In summary, from the storage and use perspective, the blocky phenylenediamine product is more suitable for conventional use and storage, and has a longer shelf life, but the synthesis process and equipment in the prior art have defects, resulting in low yield of the finished product. Meanwhile, the flaky phenylenediamine is formed by condensing and slicing blocky phenylenediamine after rectification, so the flaky phenylenediamine can be regarded as a product obtained by adding a slicing process to the blocky phenylenediamine. Therefore, it is desirable to provide a synthesis method and a reaction apparatus for improving the yield of phenylenediamine.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention provides the method for synthesizing p-phenylenediamine, which can effectively improve the yield of the p-phenylenediamine, reduce the pollution of waste liquid and waste gas and reduce the labor intensity.
The purpose of the invention is realized by the following technical scheme:
a synthetic method for improving the yield of p-phenylenediamine comprises the following steps:
(1) pumping a sodium sulfide solution into a first reaction kettle, injecting cold water into a jacket of the first reaction kettle, and adding p-nitroaniline into a kettle body of the first reaction kettle to perform reduction reaction;
(2) adding nitroaniline with the same amount as that in the step (1) into a kettle body of the first reaction kettle, carrying out reduction reaction, and generating a phenylenediamine solution, a sodium thiosulfate solution and a sodium hydroxide solution after the reduction reaction;
(3) sampling and analyzing the materials in the first reaction kettle, and reducing the temperature in the reaction kettle to 30 ℃ when the content of nitroaniline is lower than 1%;
(4) carrying out negative pressure distillation on the materials in the first reaction kettle under a vacuum condition, distilling out a sodium thiosulfate solution under the vacuum condition, and carrying out centralized purification treatment on the sodium thiosulfate solution;
(5) distilling the residual materials in the first reaction kettle under the vacuum condition and distilling a phenylenediamine solution under the vacuum condition;
(6) putting the phenylenediamine solution distilled in the step (5) into a second reaction kettle for crystallization treatment to obtain a phenylenediamine crude product;
(7) and (4) rectifying the phenylenediamine crude product prepared in the step (6) to sublimate the phenylenediamine in the phenylenediamine crude product and desublimate the phenylenediamine in a kettle top condenser of a third reaction kettle, and slicing and packaging the collected high-purity phenylenediamine.
In order to further realize the method, the part ratio of the sodium sulfide to the nitroaniline in the step (1) is 1.5-1.55: 1.15-1.25.
In order to further realize the invention, the reaction temperature in the step (1) is 55 ℃, and the reaction time is 1 hour.
In order to further realize the invention, the reaction temperature in the step (2) is 95 ℃, and the reaction time is 8 hours.
In order to further realize the invention, in the step (4), the material in the first reaction kettle is distilled under negative pressure at the temperature of 85-95 ℃.
In order to further realize the invention, the material remained in the first reaction kettle in the step (5) is subjected to negative pressure distillation at the temperature of 165-170 ℃.
In order to further realize the invention, the second reaction device in the step (6) comprises a kettle body, a kettle cover and a jacket, wherein the kettle body is a flat cuboid, a tray for storing phenylenediamine liquid is detachably arranged in the kettle body, and a sealing rubber ring is arranged between the kettle cover and the kettle body; the jacket is arranged right below the kettle body, one end of the jacket is provided with a medium inlet, and the other end of the jacket is provided with a medium outlet; the inside of the jacket is provided with a plurality of groups of baffles which are arranged in a parallel and staggered mode at intervals, so that the medium in the jacket flows in an S shape and flows out of the medium outlet in a circuitous way from the medium inlet.
In order to further realize the invention, the liquid level height of the phenylenediamine solution in the step (6) in the second reaction kettle is 3-10 cm.
In order to further realize the invention, the liquid level height of the phenylenediamine solution in the step (6) in the second reaction kettle is 5-7 cm.
In order to further realize the invention, in the step (7), the crude phenylenediamine is rectified under the conditions of the temperature of 165-170 ℃ and vacuum.
The invention has the beneficial effects that:
(1) according to the synthetic method for improving the yield of phenylenediamine, nitroaniline is used as a raw material, sodium sulfide is used as a reducing agent, reduction reaction is carried out at high temperature, and nitroaniline is added into the first reaction kettle twice, so that the reaction is more sufficient, and the yield of phenylenediamine in the synthetic process is improved. The method comprises the steps of carrying out negative pressure distillation on phenylenediamine solution, sodium thiosulfate solution and sodium hydroxide solution generated in a first reaction kettle under a vacuum condition, distilling the sodium thiosulfate solution and the phenylenediamine solution in sequence, and then crystallizing and rectifying the phenylenediamine solution, so that impurities in the finished phenylenediamine are few, the precision is high, the yield of the finished phenylenediamine is high, the yield of the phenylenediamine in the prior art is reduced by less than 80%, and is increased to more than 90%.
(2) The invention relates to a synthetic method for improving the yield of phenylenediamine, wherein a second reaction device in the step (6) comprises a kettle body, a kettle cover and a jacket, wherein the kettle body is in a flat cuboid shape, the jacket is in a flat cuboid shape, one end of the jacket is provided with a medium inlet, and the other end of the jacket is provided with a medium outlet; the inside of the jacket is provided with a plurality of groups of baffles which are arranged in a parallel and staggered mode at intervals, so that the medium in the jacket flows in an S shape and flows out of the medium outlet in a circuitous way from the medium inlet. The setting of the baffle in the clamp cover has effectively prolonged the flow time of medium in the clamp cover, has increased the area of contact of medium and cauldron body bottom for the area of heat exchange is big, and the cooling is more even. The problem of corner vacuum easily formed when the straight line style rivers flow through reation kettle, lead to partial region heat exchange effect poor, avoided phenylenediamine solution in the crystallization process phenylenediamine's cooling inequality, cause the yields low is avoided.
(3) The synthetic method for improving the yield of phenylenediamine comprises the steps of carrying out negative pressure distillation under a vacuum condition, and conveying a distilled sodium thiosulfate aqueous solution to a purification section for treatment; there is a small amount of residue in the distillation process, handles as dangerous solid waste is unified, has not only reduced the impurity of finished product phenylenediamine, has improved the yields, moreover, waste liquid centralized processing has avoided causing the pollution to the environment, can retrieve the recycle to the waste liquid. The waste gas in the second reaction kettle is collected and treated in a centralized manner, so that the air pollution caused by the discharge of the waste gas in the kettle body is avoided.
(4) According to the synthetic method for improving the yield of phenylenediamine, the liquid level height of phenylenediamine is controlled to be 3-10cm in the crystallization process, and preferably, the liquid level height is 5-7 cm. The liquid level is too low, so that the thickness of the phenylenediamine crystal is not enough, the phenylenediamine is changed into flaky phenylenediamine, and the phenylenediamine is easily oxidized and blackened in the storage process; if the liquid level is too high, the heat exchange efficiency of the middle portion of the phenylenediamine liquid becomes low. Oxidation easily occurs during cooling. Therefore, in the liquid level range of 3-10cm, the cooling speed of the phenylenediamine is ideal, and the black product rate is low; meanwhile, the formed large phenylenediamine can be further crushed into small pieces for subpackage, and the storage and the use of the finished phenylenediamine are facilitated.
(5) According to the synthetic method for improving the yield of phenylenediamine, the tray for storing phenylenediamine liquid is arranged in the second reaction kettle in the step (6), so that the massive phenylenediamine fine product after final cooling can be conveniently taken out, the labor intensity of workers is reduced, and the labor efficiency is high.
Drawings
FIG. 1 is a schematic view of the structure of a crystallization vessel according to the present invention;
fig. 2 is a cross-sectional view of fig. 1 taken along line AA'.
Detailed Description
The technical solution of the present invention is explained below with reference to specific embodiments.
A synthetic method for improving the yield of phenylenediamine comprises the following steps:
(1) pumping a sodium sulfide solution into a first reaction kettle, injecting cold water into a jacket of the first reaction kettle, adding nitroaniline into a kettle body of the first reaction kettle, slowly heating the first reaction kettle to 55 ℃, and carrying out stirring reduction reaction for 1 hour; wherein the part ratio of the sodium sulfide to the nitroaniline is 1.5-1.55: 1.15-1.25;
(2) after reacting for 1 hour, stopping stirring, and adding nitroaniline with the same amount as that in the step (1) into the kettle body of the first reaction kettle to ensure that the part ratio of the sodium sulfide to the nitroaniline is 1.5-1.55: 2.3-2.5; slowly raising the temperature in the first reaction kettle to 95 ℃, stirring and preserving the temperature for 8 hours; generating phenylenediamine solution, sodium thiosulfate solution and sodium hydroxide solution after reduction reaction in the first reaction kettle;
(3) sampling and analyzing the materials in the first reaction kettle, and reducing the temperature in the reaction kettle to 30 ℃ when the content of nitroaniline is lower than 1%;
(4) adding heat conducting oil into a jacket of the first reaction kettle to heat materials in the first reaction kettle to 85-95 ℃; carrying out negative pressure distillation on the material in the first reaction kettle under the vacuum condition, directly distilling sodium thiosulfate (with the boiling point of 100 ℃) to a receiving tank, and sending the distilled sodium thiosulfate aqueous solution to a purification section for treatment;
(5) after the distillation of the sodium thiosulfate is finished, the temperature of the remaining materials in the first reaction kettle is continuously raised to 165-170 ℃, and the phenylenediamine liquid is distilled out under the vacuum condition; a small amount of residues exist in the distillation process, and are treated as dangerous solid wastes in a unified way;
(6) putting the phenylenediamine solution distilled in the step (5) into a second reaction kettle for crystallization treatment to obtain a phenylenediamine crude product; wherein the liquid level height of the phenylenediamine solution in the second reaction kettle is 3-10cm, preferably, the liquid level height of the phenylenediamine solution is 5-7 cm;
(7) rectifying the phenylenediamine crude product prepared in the step (6) at the temperature of 165-; and slicing and packaging the collected high-purity phenylenediamine, and uniformly collecting and treating a small amount of residues generated after rectification as dangerous substances.
As shown in fig. 1-2, the second reaction device in step (6) of the synthesis method for improving the yield of phenylenediamine comprises a kettle body 1, a kettle cover 2, and a jacket 3, wherein:
the kettle body 1 is used for containing reaction solution and providing a generating space for the synthesis of phenylenediamine. The kettle body 1 is in a flat cuboid shape, the kettle body 1 is made of stainless steel materials, and the kettle body 1 is realized by adopting the prior art. Furthermore, the tray 11 used for storing phenylenediamine liquid is detachably arranged in the kettle body, so that the cooled blocky phenylenediamine is taken out and cut into blocks conveniently, the labor intensity is reduced, and the labor efficiency is higher.
The kettle cover 2 is used for sealing an opening part of the kettle body 1 and is matched with the kettle body 1 to provide a sealed space for the synthesis of phenylenediamine. Be equipped with charge door 21 on the kettle cover 2, charge door 21 is equipped with the charging valve, arranges the pipeline in the kettle body 1 through the charge door during reinforced for the pipeline is located 2-3cm department above the tray, avoids liquid to splash. A sealing rubber ring is arranged between the kettle cover 2 and the kettle body 1 and used for preventing the leakage of liquid/gas in the kettle body 1. The kettle cover 2 is made of high temperature resistant, pressure resistant and difficult cracking iron cover or stainless steel cover. An anti-corrosion protective layer is arranged in the kettle cover 2, so that the kettle cover 2 is effectively prevented from being corroded by corrosive gas; wherein, the anti-corrosion protective layer is a fluoroplastic coating, and preferably, the fluoroplastic is polytetrafluoroethylene, fluorinated ethylene propylene or PFA plastic.
The jacket 3 is used for matching with the kettle body 1 to realize the functions of heating, cooling and the like in the chemical reaction process. The jacket 3 is arranged right below the kettle body 1, the jacket 3 is in a flat cuboid shape, one end of the jacket 3 is provided with a medium inlet 31, and the other end of the jacket 3 is provided with a medium outlet 32; a plurality of groups of baffles 33 which are arranged in parallel and staggered at intervals are arranged in the jacket 3, so that the medium in the jacket 3 flows in an S shape and bypasses from the medium inlet 31 to the medium outlet 32. The arrangement of the baffle 33 in the jacket 3 prolongs the flowing time of the medium in the jacket 3, and increases the contact area of the medium and the bottom of the kettle body 1, so that the heat exchange area is large, and the condensation/heat conduction is uniform.
The above description is only a preferred embodiment of the present invention, the present invention is not limited to the above embodiment, and there may be some slight structural changes in the implementation, and if there are various changes or modifications to the present invention without departing from the spirit and scope of the present invention, and within the claims and equivalent technical scope of the present invention, the present invention is also intended to include those changes and modifications.
Claims (9)
1. A synthetic method for improving the yield of phenylenediamine is characterized by comprising the following steps:
(1) pumping the sodium sulfide solution into a first reaction kettle, injecting cold water into a jacket of the first reaction kettle, and adding nitroaniline into a kettle body of the first reaction kettle to perform reduction reaction;
(2) adding p-nitroaniline with the same amount as that in the step (1) into a kettle body of a first reaction kettle, carrying out reduction reaction, and generating a phenylenediamine solution, a sodium thiosulfate solution and a sodium hydroxide solution after the reduction reaction;
(3) sampling and analyzing the materials in the first reaction kettle, and reducing the temperature in the reaction kettle to 30 ℃ when the content of the paranitroaniline is lower than 1 percent;
(4) carrying out negative pressure distillation on the materials in the first reaction kettle under a vacuum condition, distilling out a sodium thiosulfate solution under the vacuum condition, and carrying out centralized purification treatment on the sodium thiosulfate solution;
(5) distilling the residual materials in the first reaction kettle under the vacuum condition and distilling a phenylenediamine solution under the vacuum condition;
(6) putting the phenylenediamine solution distilled in the step (5) into a second reaction kettle for crystallization treatment to obtain a phenylenediamine crude product;
(7) rectifying the phenylenediamine crude product prepared in the step (6) to sublimate the phenylenediamine in the phenylenediamine crude product and desublimate the phenylenediamine in a kettle top condenser of a third reaction kettle, and slicing and packaging the collected high-purity phenylenediamine;
the second reaction device in the step (6) comprises a kettle body, a kettle cover and a jacket, wherein the kettle body is a flat cuboid, a tray for storing phenylenediamine liquid is detachably arranged in the kettle body, and a sealing rubber ring is arranged between the kettle cover and the kettle body; the jacket is arranged right below the kettle body, one end of the jacket is provided with a medium inlet, and the other end of the jacket is provided with a medium outlet; the inside of the jacket is provided with a plurality of groups of baffles which are arranged in a parallel and staggered mode at intervals, so that the medium in the jacket flows in an S shape and flows out of the medium outlet in a circuitous way from the medium inlet.
2. The synthesis method for improving the yield of phenylenediamine according to claim 1, wherein the ratio of sodium sulfide to nitroaniline in step (1) is 1.5-1.55: 1.15-1.25.
3. The method for synthesizing phenylenediamines with improved yield according to claim 1, wherein the reaction temperature in step (1) is 55 ℃ and the reaction time is 1 hour.
4. The method as claimed in claim 1, wherein the reaction temperature in step (2) is 95 ℃ and the reaction time is 8 hours.
5. The synthesis method for improving the yield of phenylenediamine according to claim 1, wherein in the step (4), the material in the first reaction kettle is subjected to negative pressure distillation at a temperature of 85-95 ℃.
6. The method as claimed in claim 1, wherein the remaining materials in the first reaction vessel in step (5) are subjected to negative pressure distillation at a temperature of 165-170 ℃.
7. The method for improving the yield of phenylenediamine according to claim 1, wherein the liquid level of the phenylenediamine solution in the second reaction vessel in step (6) is 3-10 cm.
8. The method for improving the yield of phenylenediamine according to claim 1, wherein the liquid level of the phenylenediamine solution in the second reaction vessel in the step (6) is 5-7 cm.
9. The method as claimed in claim 1, wherein the crude phenylenediamine product in the step (7) is rectified at a temperature of 165-170 ℃ under vacuum.
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102491905A (en) * | 2011-11-18 | 2012-06-13 | 江苏科圣化工装备工程有限公司 | Method and device for co-production of o-phenylenediamine and p-phenylenediamine |
| CN102531921A (en) * | 2010-12-24 | 2012-07-04 | 中国石油化工股份有限公司 | Refining and shaping process of p-phenylenediamine |
| CN106316863A (en) * | 2016-08-13 | 2017-01-11 | 安徽东至广信农化有限公司 | Efficient o-phenylenediamine recovery method |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102531921A (en) * | 2010-12-24 | 2012-07-04 | 中国石油化工股份有限公司 | Refining and shaping process of p-phenylenediamine |
| CN102491905A (en) * | 2011-11-18 | 2012-06-13 | 江苏科圣化工装备工程有限公司 | Method and device for co-production of o-phenylenediamine and p-phenylenediamine |
| CN106316863A (en) * | 2016-08-13 | 2017-01-11 | 安徽东至广信农化有限公司 | Efficient o-phenylenediamine recovery method |
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