CN114249657B - Method for continuously preparing DCB - Google Patents
Method for continuously preparing DCB Download PDFInfo
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- CN114249657B CN114249657B CN202111494554.8A CN202111494554A CN114249657B CN 114249657 B CN114249657 B CN 114249657B CN 202111494554 A CN202111494554 A CN 202111494554A CN 114249657 B CN114249657 B CN 114249657B
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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
- C07C209/54—Preparation of compounds containing amino groups bound to a carbon skeleton by rearrangement reactions
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
Abstract
The invention provides a method for continuously preparing DCB, the preparation method is realized by a circulating device, the circulating device comprises a reaction kettle and a dispersing pump which are sequentially communicated, the dispersing pump can continuously transfer the reaction liquid in the reaction kettle, so that the sticky materials generated in the transposition reaction process are dispersed and crushed, the mixing effect is enhanced, the reaction is accelerated, and the reaction selectivity and stability are better; meanwhile, the preparation method can continuously carry out transposition reaction, improves the efficiency of preparing DCB and effectively reduces the energy consumption.
Description
Technical Field
The invention relates to the technical field of organic pigment synthesis, in particular to a method for continuously preparing DCB.
Background
3,3' -dichloro benzidine is called DCB for short, is an important intermediate for producing dichloro benzidine yellow organic pigment, and yellow pigment produced by using the same as raw material accounts for about 25% of the total yield of organic pigment, and the organic pigment is widely applied to the coloring of printing ink, paint, rubber and plastic, the production of pigment printing slurry and pigment dyeing slurry, and the like.
The preparation of DCB is to take o-nitrochlorobenzene as raw material, obtain toluene solution of DCB reducing substance through hydrogenation reaction, and then carry out transposition reaction with hydrochloric acid to obtain DCB mixed slurry.
In industry, the equipment adopted for carrying out the transposition reaction is mainly a batch glass lining reaction kettle, and is worth integrating, when the transposition reaction is carried out, the generated DCB hydrochloride is difficult to dissolve in toluene and slightly soluble in high-concentration hydrochloric acid and water, so that after the reaction is carried out to a certain extent, the viscosity of the reaction liquid gradually becomes large, and crystallization is carried out, so that the reaction is uneven, the reaction time is too long, byproducts are increased, and the conversion rate and selectivity of the reaction are affected. Meanwhile, in order to achieve the production aim, a plurality of reaction kettles are carried out simultaneously, and the power consumption of equipment is also larger.
Disclosure of Invention
The invention aims to provide a method for continuously preparing DCB, which can disperse and crush sticky materials generated in the process of transposition reaction, quickens the reaction, and has better reaction selectivity and stability; the preparation method can continuously carry out transposition reaction, improves the efficiency of preparing DCB and effectively reduces the energy consumption.
In order to achieve the above object, the present invention provides a method for continuously preparing DCB, which is implemented by a circulation device comprising a reaction kettle and dispersion pumps which are sequentially communicated, wherein each dispersion pump is provided with at least two regulating valves for circularly transferring reaction liquid in the reaction kettle and controlling the volume of the reaction liquid in the reaction kettle, respectively.
Specifically, the circulation device includes: the device comprises a first-stage reaction kettle, a first-stage dispersion pump, a second-stage reaction kettle, a second-stage dispersion pump and a reaction liquid receiving tank, wherein the first-stage dispersion pump is arranged between the first-stage reaction kettle and the second-stage reaction kettle, is used for circularly transferring the reaction liquid in the first-stage reaction kettle and controlling the volume of the reaction liquid in the first-stage reaction kettle, and is used for transferring part of the reaction liquid in the first-stage reaction kettle into the second-stage reaction kettle; the secondary dispersion pump is arranged between the secondary reaction kettle and the reaction liquid receiving tank, and is used for circularly transferring the reaction liquid in the secondary reaction kettle, controlling the volume of the reaction liquid in the secondary reaction kettle and transferring part of the reaction liquid in the secondary reaction kettle into the reaction liquid receiving tank.
Wherein, a first-stage circulation regulating valve and a first-stage transfer regulating valve for controlling the communication state are respectively arranged between the first-stage dispersing pump and the first-stage reaction kettle and between the first-stage dispersing pump and the second-stage reaction kettle; and a secondary circulation regulating valve and a secondary transfer regulating valve for controlling the communication state are respectively arranged between the secondary dispersion pump and the secondary reaction kettle and between the secondary dispersion pump and the reaction liquid receiving tank.
When the automatic regulating valve is worth integrating, the regulating valves are all automatic regulating valves, and the flow of materials can be automatically controlled. Preferably, the first-stage reaction kettle and the second-stage reaction kettle are both provided with a radar liquid level meter, the radar liquid level meter monitors the liquid volume in the reaction kettle in real time, and information is fed back to a corresponding automatic regulating valve so as to control the flow of materials and the material volumes of the first-stage reaction kettle and the second-stage reaction kettle.
Further, a DCB reduction toluene solution input pump and a hydrochloric acid solution input pump are arranged at the feeding end of the primary reaction kettle, and each input pump can input liquid into the reaction kettle according to preset flow.
Further, the primary dispersion pump and the secondary dispersion pump are special viscous material dispersion pumps and are titanium material pumps or fluoroplastic pumps.
Further, the liquid volumes of the primary reaction kettle and the secondary reaction kettle are 8-10m 3 。
Specifically, the method for preparing DCB by the circulating device comprises the following steps:
step one: adding a certain amount of 15-25% hydrochloric acid into the first-stage reaction kettle, starting stirring, opening a first-stage circulation regulating valve, starting a first-stage dispersing pump, and keeping the first-stage transfer regulating valve closed;
step two: simultaneously injecting DCB reduction toluene solution and 30-35% hydrochloric acid into the first-stage reaction kettle according to a preset flow;
step three: monitoring the liquid level in the first-stage reaction kettle, and when the liquid level in the first-stage reaction kettle reaches a first preset liquid level, opening a first-stage transfer regulating valve, wherein the first preset liquid level is 60-80%, and controlling the liquid level in the first-stage reaction kettle (11) to be kept at 60-80%;
step four: monitoring the liquid level in the secondary reaction kettle, when the liquid level in the secondary reaction kettle reaches a second preset liquid level, opening a secondary circulation regulating valve, and starting a secondary dispersion pump, wherein the second preset liquid level is 10-20%, and keeping the secondary transfer valve closed;
step five: when the liquid level in the secondary reaction kettle reaches a first preset liquid level, a secondary transfer regulating valve is opened, materials are conveyed to a reaction receiving tank, and the volume of the liquid in the secondary reaction kettle is controlled to be kept at 60-80% of the total volume.
Further, in step oneAdding 2m into the primary reaction kettle in advance 3 Is a solution of 20% hydrochloric acid.
Further, in the first step, the flow rate of the liquid circularly transferred by the primary dispersion pump into the primary reaction kettle is 50-100m 3 /h。
Further, in the second step, the flow rate of the DCB reduction toluene solution entering the first-stage reaction kettle is 800-1000kg/h, and the flow rate of the hydrochloric acid entering the first-stage reaction kettle is 950-1200kg/h.
Further, in the second step, the mass ratio of 2,2' -dichlorohydrazobenzene to toluene in the toluene solution of DCB reduced matter was = (1-2): 1.
Further, in the second step, the temperature in the primary reaction kettle and the secondary reaction kettle is controlled to be 30-35 ℃.
Further, in the fourth step, the flow rate of the liquid circularly transferred into the second-stage reaction kettle by the second-stage dispersion pump is 50-100m 3 /h。
The invention has the beneficial effects that:
1. the preparation method provided by the invention can continuously feed and discharge, the reaction is continuously carried out, the reaction time is short, the conversion rate is good, and the reaction selectivity and stability are good.
2. The preparation method provided by the invention can continuously carry out transposition reaction, replaces an intermittent reaction mode, simplifies the process flow of DCB transposition reaction, and improves the efficiency of preparing DCB.
3. The preparation method provided by the invention adopts a small volume of the reaction kettle, has small quantity and low energy consumption.
4. The preparation method provided by the invention is carried out in a closed circulation system, prevents the evaporation of toluene liquid and reduces the emission of organic pollutants.
Drawings
FIG. 1 is a process flow diagram of the preparation of DCB according to the present invention.
Reference numerals illustrate:
11. a first-stage reaction kettle; 12. a second-stage reaction kettle; 21. a first-stage dispersion pump; 22. a secondary dispersion pump; 31. a reaction liquid receiving tank; 41. hydrochloric acid is input into the pump; 42. feeding DCB raw materials into a pump; 51. a primary circulation regulating valve; 52. a first-stage transfer regulating valve; 61. a secondary circulation regulating valve; 62. a secondary transfer regulating valve; 71. a primary radar level gauge; 72. a secondary radar level gauge; 81. a primary stirrer; 82. a secondary stirrer; 91. a primary temperature control unit; 92. and a secondary temperature control unit.
Detailed Description
So that the manner in which the above recited objects, features and advantages of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to the embodiments thereof which are illustrated in the appended drawings, wherein the detailed description is given above, and wherein the detailed description is not to limit the scope of the invention as claimed.
The following detailed description of embodiments of the invention is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
In the description of the present invention, it should be noted that, directions or positional relationships indicated by terms such as "upper", "lower", "left", "right", "inner", "outer", "front", "rear", etc., are directions or positional relationships based on those shown in the drawings, or are directions or positional relationships conventionally put in use of the inventive product, are merely for convenience of describing the present invention and simplifying the description, and are not indicative or implying that the apparatus or element to be referred to must have a specific direction, be configured and operated in a specific direction, and thus should not be construed as limiting the present invention.
In the description of the present invention, unless explicitly stated and limited otherwise, the terms "mounted," "configured," "connected," and the like are to be construed broadly as, for example, "connected," either permanently or detachably, or integrally, either mechanically or electrically, or indirectly, or through intermediaries, in communication between two elements. The specific meaning of the above terms in the present invention will be understood in specific cases by those of ordinary skill in the art.
Embodiment one:
in this embodiment, the preparation of DCB is performed by a recycling apparatus, and as can be seen from the process flow chart of fig. 1, the recycling apparatus for preparing DCB includes: the reaction kettle 11, the primary dispersion pump 21, the secondary reaction kettle 12, the secondary dispersion pump 22 and the reaction liquid receiving tank 31, wherein the primary radar level gauge 71 and the secondary radar level gauge 71, the primary stirrer 81 and the secondary stirrer 82, the primary temperature control unit 91 and the secondary temperature control unit 92 are respectively arranged on the primary reaction kettle 11 and the secondary reaction kettle 12; the feeding end of the primary dispersion pump 21 is connected with the discharging end of the primary reaction kettle 11, and the discharging end of the primary dispersion pump 21 is connected with the feeding ends of the primary reaction kettle 11 and the secondary reaction kettle 12; the feed end of the secondary dispersion pump 22 is connected with the discharge end of the secondary reaction kettle 12, the discharge end of the secondary dispersion pump 22 is connected with the feed ends of the secondary reaction kettle 12 and the reaction liquid receiving tank 31, wherein a primary circulation regulating valve 51 and a primary transfer regulating valve 52 are respectively arranged on a pipeline between the primary reaction kettle 11 and the secondary reaction kettle 12 which are communicated with the discharge end of the primary dispersion pump 21, and a secondary circulation regulating valve 61 and a secondary transfer regulating valve 62 are respectively arranged on a functional pipeline between the secondary reaction kettle 12 and the reaction liquid receiving tank 31 which are communicated with the discharge end of the secondary dispersion pump 22.
Preferably, the primary circulation regulating valve 51, the primary transfer regulating valve 52, the secondary circulation regulating valve 61 and the secondary transfer regulating valve 62 are all automatic regulating valves, and when the radar level gauge monitors the liquid volume in the reaction kettle in real time, information can be fed back to the corresponding automatic regulating valves so as to automatically control the flow rate of materials and the material volumes of the primary reaction kettle 11 and the secondary reaction kettle 12.
Preferably, the primary temperature control unit 91 and the secondary temperature control unit 92 are both jacket layers arranged on the outer layers of the primary reaction kettle 11 and the secondary reaction kettle 12, and are provided with a water inlet and a water outlet, preferably, the water inlet is arranged at the lower end of the reaction kettle, and the water outlet is arranged at the upper end of the reaction kettle, so that the cooling water can cool the reaction kettle well.
Preferably, the primary dispersing pump 21 and the secondary dispersing pump 22 are special viscous material dispersing pumps, and are titanium material pumps or fluoroplastic pumps.
Further, a DCB raw material input pump 42 and a hydrochloric acid input pump 41 are provided at the feed end of the primary reaction kettle 11, and preferably, the input pump is a metering pump, which can input liquid into the primary reaction kettle 11 according to a preset flow rate.
In this example, the metathesis reaction of DCB was carried out by the above-mentioned circulation apparatus, using a continuous reaction method, specifically, the method for preparing DCB comprises the steps of:
step one: to 8m 3 2m of the primary reaction kettle 11 is added 3 Starting the primary stirrer 81, opening the primary circulation regulating valve 51, starting the primary dispersing pump 21, and controlling the flow rate of the liquid injected into the primary reaction kettle 11 by the primary dispersing pump 21 to be 100m 3 /h；
Step two: simultaneously starting a DCB raw material input pump 42 and a hydrochloric acid input pump 41, simultaneously injecting a DCB reduction toluene solution and a 31% hydrochloric acid solution into the primary reaction kettle 11, and controlling the temperature in the primary reaction kettle 11 to be kept at 30-35 ℃ through a primary temperature control unit 91;
wherein, the injection speed of the toluene solution of the DCB reduction product is 800kg/h, and the injection speed of the hydrochloric acid solution is 1000kg/h. And the mass ratio of 2,2' -dichlorohydrazobenzene to toluene in the DCB reduction toluene solution is 2:1.
Step three: the volume of the liquid in the primary reaction kettle 11 is monitored by a primary radar level gauge 71, and when the volume of the reaction liquid reaches 70%, the primary dispersion pump 21 is opened for 8m 3 A first-stage transfer regulating valve 52 of the second-stage reaction kettle 12 transfers part of the reaction liquid into the second-stage reaction kettle 12, and regulates a first-stage circulation regulating valve 51 and the first-stage transfer regulating valve 52 to control the volume of the reaction liquid in the first-stage reaction kettle 11 to be kept at 60-80%; and the temperature in the secondary reaction kettle 12 is controlled to be kept between 30 and 35 ℃ by a secondary temperature control unit 92.
Step four: the volume of the liquid in the secondary reaction kettle 12 is monitored by a secondary radar level gauge 72, and when the volume reaches 15%, the secondary circulation regulating valve 61 is opened, and secondary dispersion is startedA pump 22 for controlling the flow rate of the liquid injected into the secondary reaction kettle 12 by the secondary dispersion pump 22 to be 100m 3 /h；
Step five: when the volume of the liquid in the secondary reaction kettle 12 reaches 70%, a secondary transfer regulating valve 62 of the secondary dispersion pump 22 communicated with the reaction liquid receiving tank 31 is opened, DCB slurry is received in the reaction receiving tank 31, and simultaneously, the secondary circulation regulating valve 61 and the secondary transfer regulating valve 62 are regulated to control the volume of the reaction liquid in the secondary reaction kettle 12 to be 60-80%.
During the continuous shift reaction, samples were taken from the pipe of the reaction liquid receiving tank 31 at different times and analyzed by high performance liquid chromatography, and the analysis data are shown in table 1:
as can be seen from the data, the sampling analysis is carried out at different times, the main content of the slurry is DCB, and a small amount of unreacted raw materials 2, 2-dichlorohydrazobenzene and partial DCB byproducts are found, and in the process of carrying out the transposition reaction continuously, the DCB content, the content of the residual raw materials and the content of the byproducts are stable in the obtained DCB slurry at different times.
Embodiment two:
in this example, the apparatus for preparing DCB is the same as the circulation apparatus for carrying out one, and a continuous reaction is adopted, specifically, the method for preparing DCB includes the steps of:
step one: to 8m 3 2m of the primary reaction kettle 11 is added 3 Starting the primary stirrer 81, opening the primary circulation regulating valve 51, starting the primary dispersing pump 21, and controlling the flow rate of the liquid injected into the primary reaction kettle 11 by the primary dispersing pump 21 to be 100m 3 /h；
Step two: simultaneously starting a DCB raw material input pump 42 and a hydrochloric acid input pump 41, simultaneously injecting a DCB reduction toluene solution and a 31% hydrochloric acid solution into the first-stage reaction kettle 11, and controlling the temperature in the reaction kettle to be kept at 30-35 ℃ through a first-stage temperature control unit 91;
wherein, the injection speed of the toluene solution of the DCB reduction product is 1000kg/h, and the injection speed of the hydrochloric acid solution is 950kg/h. And the mass ratio of the 2,2' -dichlorohydrazobenzene to toluene in the DCB reduction toluene solution is 1.5:1.
Step three: the volume of the liquid in the primary reaction kettle 11 is monitored by a primary radar level gauge 71, and when the volume of the reaction liquid reaches 70%, the primary dispersion pump 21 is opened for 8m 3 The primary transfer regulating valve 52 of the secondary reaction kettle 12 transfers part of the reaction liquid into the secondary reaction kettle 12, the primary circulation regulating valve 51 and the primary transfer regulating valve 52 are regulated to control the volume of the reaction liquid in the primary reaction kettle 11 to be kept at 60-80%, and the temperature in the secondary reaction kettle 12 is controlled to be kept at 30-35 ℃ through the secondary temperature control unit 92.
Step four: the volume of the liquid in the secondary reaction kettle 12 is monitored by a secondary radar level gauge 72, when the volume reaches 15%, a secondary circulation regulating valve 61 is opened, a secondary dispersing pump 22 is opened, and the flow rate of the liquid injected into the secondary reaction kettle 12 by the secondary dispersing pump 22 is controlled to be 100m 3 /h；
Step five: when the volume of the liquid in the secondary reaction kettle 12 reaches 70%, the secondary dispersion pump 22 is opened to communicate with the secondary transfer regulating valve 62 of the reaction liquid receiving tank 31, DCB slurry is received in the reaction receiving tank, and simultaneously, the secondary circulation regulating valve 61 and the secondary transfer regulating valve 62 are regulated to control the volume of the reaction liquid in the secondary reaction kettle 12 to be 60-80%.
During the continuous shift reaction, samples were taken from the pipe of the reaction liquid receiving tank 31 at different times and analyzed by high performance liquid chromatography, and the analysis data are shown in table 2:
as can be seen from the data, the sampling analysis is carried out at different times, the main content of the slurry is DCB, and a small amount of unreacted raw materials 2, 2-dichlorohydrazobenzene and partial DCB byproducts are found, and in the process of carrying out the transposition reaction continuously, the DCB content, the content of the residual raw materials and the content of the byproducts are stable in the obtained DCB slurry at different times.
In order to fully illustrate the manner in which the continuous metathesis reaction provided by the present invention is capable of producing DCB better, the present invention is also contrasted with batch reactions.
Comparative example:
in the comparative example, the apparatus for preparing DCB is a reaction kettle, the reaction kettle is provided with a stirring device, a temperature control device and a hydrochloric acid dropwise adding device, and the method for preparing DCB by the reaction kettle comprises the following steps:
to 8m 3 5000kg of DCB reduction toluene solution is injected into the reaction kettle, wherein the mass ratio of 2,2' -dichlorohydrazobenzene to toluene is 1.5:1, a stirrer is started, 6250kg of 31% hydrochloric acid solution is dropwise added into the reaction kettle, the dropwise addition of hydrochloric acid is controlled within 10 hours, the reaction temperature is controlled to be kept at 30-35 ℃, and the reaction is carried out for 30 hours after the addition of hydrochloric acid, so that the reaction end point is reached.
Sampling the slurry in the reaction kettle for high performance liquid chromatography analysis, wherein the specific experimental data are shown in the following table:
according to the experimental data, the DCB is prepared by adopting a traditional intermittent reaction mode, the reaction conversion rate is slightly lower than that of a continuous reaction mode, the unreacted raw materials are slightly higher than that of a continuous reaction mode, the generated DCB byproduct liquid is slightly higher than that of the continuous reaction mode, the reaction end point can be reached only in a long time, the reaction liquid becomes sticky gradually in the intermittent reaction process, the reaction is uneven, the reaction time is prolonged, the probability of byproduct generation is increased, meanwhile, the reaction is needed to be carried out in batches, the preparation of the next batch of products can be carried out after one batch of reaction is ended, the time consumption is long, and the product preparation efficiency is low. In order to achieve the production goal, a plurality of reaction kettles are needed to be carried out simultaneously, the quantity of the reaction kettles is large, the energy consumption is high, and the time and the cost for generating are increased.
Finally, it should be noted that the above embodiments are only for illustrating the technical solution of the present invention, and not for limiting the same, and although the present invention has been described in detail with reference to the above embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may be modified or some or all of the technical features may be replaced with other technical solutions, which do not depart from the scope of the technical solutions of the embodiments of the present invention.
Claims (6)
1. A process for the continuous preparation of DCB, characterized in that it is carried out by a circulation device, in which,
the circulation device includes: the device comprises a first-stage reaction kettle (11), a first-stage dispersion pump (21), a second-stage reaction kettle (12), a second-stage dispersion pump (22) and a reaction liquid receiving tank (31);
the liquid inlet end of the primary dispersion pump (21) is communicated with the liquid outlet end of the primary reaction kettle (11), the liquid outlet end of the primary dispersion pump (21) is communicated with the liquid inlet ends of the primary reaction kettle (11) and the secondary reaction kettle (12),
a primary circulation regulating valve (51) and a primary transfer regulating valve (52) for controlling the communication state are respectively arranged on the communication pipelines of the primary dispersion pump (21) and the primary reaction kettle (11) and the secondary reaction kettle (12);
the liquid inlet end of the secondary dispersion pump (22) is communicated with the liquid outlet end of the secondary reaction kettle (12), the liquid outlet end of the secondary dispersion pump (22) is communicated with the liquid inlet ends of the secondary reaction kettle (12) and the reaction liquid receiving tank (31),
a secondary circulation regulating valve (61) and a secondary transfer regulating valve (62) are respectively arranged on the communication pipelines of the secondary dispersing pump (22) and the secondary reaction kettle (12) and the reaction liquid receiving tank (31);
the method comprises the following steps:
step one: adding a certain amount of 15-25% hydrochloric acid into the first-stage reaction kettle (11), starting stirring, opening a first-stage circulation regulating valve (51), starting a first-stage dispersing pump (21), and keeping a first-stage transfer regulating valve (52) closed;
step two: simultaneously injecting DCB reduction toluene solution and 30-35% hydrochloric acid into the first-stage reaction kettle (11) according to a preset flow;
step three: monitoring the liquid level in the first-stage reaction kettle (11), and when the liquid level in the first-stage reaction kettle (11) reaches a first preset liquid level, opening a first-stage transfer regulating valve (52), wherein the first preset liquid level is 60-80% of the total volume of the reaction kettle, and controlling the liquid level in the first-stage reaction kettle (11) to be kept at 60-80% of the total volume;
step four: monitoring the liquid level in the secondary reaction kettle (12), and when the liquid level in the secondary reaction kettle (12) reaches a second preset liquid level, opening a secondary circulation regulating valve (61), wherein the second preset liquid level is 10-20% of the total volume of the reaction kettle, opening a secondary dispersing pump (22), and keeping a secondary transfer regulating valve (62) closed;
step five: when the liquid level in the secondary reaction kettle (12) reaches a first preset liquid level, a secondary transfer regulating valve (62) is opened, materials are conveyed to a reaction liquid receiving tank (31), and the liquid volume in the secondary reaction kettle (12) is controlled to be kept at 60-80% of the total volume;
in the first step, the flow rate of the primary dispersion pump (21) is 50-100m 3 /h；
In the second step, the mass ratio of 2,2' -dichlorohydrazobenzene to toluene in the DCB reduction toluene solution is = (1-2) 1;
the total volume of the primary reaction kettle (11) capable of containing liquid is 8-10m 3 The method comprises the steps of carrying out a first treatment on the surface of the The total volume of the secondary reaction kettle (12) capable of containing liquid is 8-10m 3 ；
In the fourth step, the flow rate of the secondary dispersion pump (22) is 50-100m 3 /h。
2. The method for continuously preparing DCB according to claim 1, wherein in the first step, 2m of the reaction mixture is previously charged into the primary reaction vessel (11) 3 Is a solution of 20% hydrochloric acid.
3. The method for continuously producing DCB according to claim 1, wherein in the second step, the flow rate of the toluene solution of the DCB reduced product into the first-stage reaction vessel (11) is 800 to 1000kg/h, and the flow rate of the hydrochloric acid into the first-stage reaction vessel (11) is 950 to 1200kg/h.
4. The method for continuously preparing DCB according to claim 1, wherein the temperature in the primary reaction vessel (11) and the secondary reaction vessel (12) is controlled to be maintained at 30-35 ℃.
5. The method for continuously preparing DCB according to claim 1, wherein the circulating means further comprises a hydrochloric acid input pump (41) and a DCB raw material input pump (42), and both the hydrochloric acid input pump (41) and the DCB raw material input pump (42) are communicated with the feed end of the primary reaction tank (11).
6. The method for continuously preparing DCB according to claim 1, wherein the primary circulation regulating valve (51), the primary transfer regulating valve (52), the secondary circulation regulating valve (61) and the secondary transfer regulating valve (62) are all automatic regulating valves, and the primary reaction kettle (11) and the secondary reaction kettle (12) are respectively provided with a primary radar level gauge (71) and a secondary radar level gauge (72); the primary radar liquid level gauge (71) monitors the liquid level in the primary reaction kettle (11) and is suitable for controlling the primary circulation regulating valve (51) and the primary transfer regulating valve (52); the secondary radar liquid level gauge (72) monitors the liquid level in the secondary reaction kettle (12) and is suitable for controlling the secondary circulation regulating valve (61) and the secondary transfer regulating valve (62).
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4559160A (en) * | 1984-02-09 | 1985-12-17 | Bofors Nobel, Inc. | Highly stable dichlorobenzidine dihydrochloride slurry and a method for preparing such |
| KR20040033627A (en) * | 2002-10-15 | 2004-04-28 | 주식회사 협화화학 | Process for the preparation of benzidine compound |
| CN110105221A (en) * | 2019-05-29 | 2019-08-09 | 江苏仁欣化工股份有限公司 | A kind of continuous production technology of 3,3 '-dichlorobenzidine hydrochlorides |
| CN111116407A (en) * | 2019-12-16 | 2020-05-08 | 浙江秦燕科技股份有限公司 | Method for preparing DCB reducing substance by continuous catalytic hydrogenation reduction |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111420712A (en) * | 2020-04-14 | 2020-07-17 | 郑州大学 | Device and method for continuously producing catalyst based on low-temperature coprecipitation method |
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4559160A (en) * | 1984-02-09 | 1985-12-17 | Bofors Nobel, Inc. | Highly stable dichlorobenzidine dihydrochloride slurry and a method for preparing such |
| KR20040033627A (en) * | 2002-10-15 | 2004-04-28 | 주식회사 협화화학 | Process for the preparation of benzidine compound |
| CN110105221A (en) * | 2019-05-29 | 2019-08-09 | 江苏仁欣化工股份有限公司 | A kind of continuous production technology of 3,3 '-dichlorobenzidine hydrochlorides |
| CN111116407A (en) * | 2019-12-16 | 2020-05-08 | 浙江秦燕科技股份有限公司 | Method for preparing DCB reducing substance by continuous catalytic hydrogenation reduction |
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