阅读说明：本技术 一种大红粉的连续化无盐环保制备方法 (Continuous salt-free environment-friendly preparation method of scarlet powder ) 是由 陈泽海 闫庆余 郭帅 孙新世 于 2019-11-28 设计创作，主要内容包括：本发明公开了一种大红粉的连续化无盐环保制备方法,其制备方法是以甲醇为溶剂,氨、硫化氢、2-氰基-4-硝基苯胺为原料,经硫代化反应生成2-氨基-5-硝基硫代苯甲酰胺,再用过氧化氢闭环得3-氨基-5-硝基-2,1-苯并异噻唑(大红粉)的工艺,实现了四釜串联连续化生产,过量氨和硫化氢被溶剂甲醇吸收后全部循环回用,反应过程中不生成含盐废液,硫代物收率可达到100％,工艺简单,环保、收率高。(The invention discloses a continuous salt-free environment-friendly preparation method of scarlet powder, which is a process for preparing 3-amino-5-nitro-2, 1-benzisothiazole (scarlet powder) by using methanol as a solvent, using ammonia, hydrogen sulfide and 2-cyano-4-nitroaniline as raw materials through a thionation reaction to generate 2-amino-5-nitrobenzamide and performing ring closure by using hydrogen peroxide, so that four-kettle series continuous production is realized, excessive ammonia and hydrogen sulfide are absorbed by the solvent methanol and then are recycled completely, no salt-containing waste liquid is generated in the reaction process, the yield of a thio-compound can reach 100%, the process is simple, the environment is protected, and the yield is high.)

1. A continuous salt-free environment-friendly preparation method of scarlet powder is characterized by comprising the following steps:

feeding, namely adding 1914 parts of methanol into 500 parts of 2-cyano-4-nitroaniline in a No. 1 reaction kettle in parts by weight, stirring until the mixture is uniformly dispersed, then adding 100 parts of liquid ammonia, stirring uniformly, slowly adding 110 parts of hydrogen sulfide, controlling the temperature in the reaction kettle to be 1-5 ℃, stopping stirring and opening a tail gas condensation reflux device after feeding for 4 hours, and feeding overflowed feed gas and non-condensable gas into a methanol falling film absorption device;

step two, carrying out heat preservation reaction, opening a discharge valve after feeding, feeding into a No. 2 reaction kettle, starting stirring, controlling the temperature in the reaction kettle to be 40-45 ℃, reacting for 4 hours, stopping stirring, opening a tail gas condensation reflux device, and feeding overflowed raw material gas and non-condensable gas into a methanol falling film absorption device;

step three, carrying out heat preservation reaction, opening a discharge valve, feeding the mixture into a No. 3 reaction kettle, starting stirring, controlling the temperature in the reaction kettle to be 55-60 ℃, reacting for 2 hours, sampling, detecting the end point, supplementing hydrogen sulfide, continuing to react to the end point, stopping stirring, opening a tail gas condensation reflux device, and feeding overflowed feed gas and non-condensable gas into a methanol falling film absorption device;

and step four, carrying out heat preservation reaction, opening a discharge valve, feeding the mixture into a No. 4 reaction kettle, starting stirring, slowly cooling the temperature in the reaction kettle to 5-10 ℃, cooling for 3 hours, stopping stirring, opening a tail gas condensation reflux device, and feeding overflowed feed gas and non-condensable gas into a methanol falling film absorption device.

Step five, centrifugally extracting, opening a discharge valve, feeding the obtained product into a centrifugal machine, feeding the obtained filter cake after centrifugation into a closed-loop reaction kettle, and carrying out closed-loop reaction by using hydrogen peroxide to obtain 3-amino-5-nitro-2, 1-benzisothiazole;

and step six, falling film absorption, wherein the filtrate from the centrifuge contains 92% of methanol, enters an absorption storage tank, is conveyed to the upper part of a falling film absorber by an absorption pump, vertically descends in a film shape along the inner wall of a tube array through a liquid phase distributor, a gas phase passes through the inner tube space from bottom to top, gas-liquid two phases carry out mass transfer on a flowing liquid film, ammonia and hydrogen sulfide in tail gas are absorbed by the methanol solution and then return to the absorption storage tank for recycling, and cooling water is introduced outside the tube array to keep the temperature in the falling film absorber at 5-10 ℃.

And seventhly, recycling, wherein 5-8% of methanol is lost in the process, 5-8% of supplemented fresh methanol enters a falling film absorption device to be mixed with the recycled methanol, ammonia and hydrogen sulfide in tail gas are absorbed, and then the mixture enters a No. 1 reaction kettle.

2. The continuous salt-free environment-friendly preparation method of scarlet powder according to claim 1, wherein in the first step, the hydrogen sulfide and 2-cyano-4-nitroaniline are subjected to a thioreaction under the action of ammonia and methanol to form a thioproduct, the concentration of the methanol is 98%, the concentration of the hydrogen sulfide is 99%, the thioproduct is 2-amino-5-nitrothioformamide, and the feeding ratio of the methanol dissolution to the thioproduct is 3: 1.

3. The continuous salt-free environment-friendly preparation method of scarlet powder according to claim 1, characterized in that the # 1 reaction kettle, the # 2 reaction kettle, the # 3 reaction kettle and the # 4 reaction kettle comprise a discharge valve, a stirring device, a temperature control device, a tail gas condensation reflux device and a methanol falling film absorption device, wherein the tail gas condensation reflux device is a methanol condenser.

4. The continuous salt-free environment-friendly preparation method of scarlet powder according to claim 1, characterized in that the 1# reaction kettle, the 2# reaction kettle, the 3# reaction kettle and the 4# reaction kettle are connected in series.

5. The continuous salt-free environment-friendly preparation method of scarlet powder according to claim 1, characterized in that the stirring speed of the first step, the second step, the third step and the fourth step is 50-150 r/min.

Technical Field

The invention relates to the technical field of scarlet powder preparation, in particular to a continuous salt-free environment-friendly preparation method of scarlet powder.

Background

The chemical name of scarlet powder is 3-amino-5-nitro-2, 1-benzisothiazole, which is an intermediate for synthesizing disperse blue 148 and is also used as an intermediate of heterocyclic disperse dyes.

The existing scarlet powder is produced by diazotizing aniline and coupling with sodium naphthol AS. The main production process comprises the following steps:

firstly, diazotization, namely discharging water in a diazotization pot, adding hydrochloric acid, slowly adding aniline under stirring, uniformly stirring, keeping the temperature at 3-5 ℃, and uniformly adding a sodium nitrite solution into the diazotization pot to react; and stopping stirring after the end point is determined to be reached, and standing for reaction for later use.

And secondly, preparing the naphthol AS sodium salt, namely putting clear water into a naphthol AS sodium salt barrel, adding NaOH and sulfonated castor oil, stirring uniformly, then adding the nekal, heating, slowly adding the naphthol AS, and stirring until the mixture is completely transparent for later use.

Thirdly, coupling, namely putting clean water in a coupling pot in advance, sieving the dissolved naphthol AS solution, putting the sieved solution into the coupling pot, stirring, adjusting the total volume, uniformly injecting the diazonium salt into the coupling pot, and performing coupling reaction, wherein the pH value is 8 and the temperature is 31 ℃ after the diazonium salt is added; after the coupling is finished, stirring, adding hydrochloric acid for acidification, stirring again after acidification, and slowly heating to 100 ℃; and (3) preserving heat, filtering, rinsing with water until the pH value is 6.5-7.0, and drying a filter cake at 80 ℃ to obtain the finished product of the scarlet powder.

The method aims at the problem that sodium hydrosulfide and ammonium chloride or ammonium sulfate are used as raw materials in the first step of the existing scarlet powder production process, and therefore salts in a filter cake need to be washed by process water in the production process, so that a large amount of salt-containing waste liquid is generated, and the waste liquid is very difficult to treat due to more than two kinds of mixed salts. Meanwhile, the waste liquid contains about 50% of methanol, so that the recovery cost is high, and the waste liquid also contains a small amount of intermediate products, so that the yield is directly influenced, and the difficulty of waste liquid treatment is increased.

In order to fundamentally overcome the technical problem of treating the salt-containing waste liquid in the production of scarlet powder, realize environment-friendly production, improve the yield and reduce the production cost, the development of a production process of scarlet powder, which has simple process, meets the environment-friendly requirement, and has low cost and high yield, is urgently needed.

Disclosure of Invention

The invention aims to overcome the technical defects and provide a continuous salt-free environment-friendly preparation method of scarlet powder, which adopts continuous production, does not generate salts in the production, omits a washing link, avoids the treatment and discharge of wastewater, realizes the recycling of excessive raw materials and solvents, reduces the consumption and cost, and has the advantages of simple process, environment protection and high yield.

In order to solve the technical problems, the technical scheme provided by the invention is as follows:

a continuous salt-free environment-friendly preparation method of scarlet powder comprises the following steps:

feeding, namely adding 1914 parts of methanol into 500 parts of 2-cyano-4-nitroaniline in a 1# reaction kettle in parts by weight, starting stirring, adding 100 parts of liquid ammonia after stirring until the mixture is uniformly dispersed, slowly adding 110 parts of hydrogen sulfide after stirring, controlling the temperature in the reaction kettle to be 1-5 ℃, stopping stirring and opening a tail gas condensation reflux device after feeding for 4 hours, and feeding overflowed feed gas and non-condensable gas into a methanol falling film absorption device

Step two, carrying out heat preservation reaction, opening a discharge valve after feeding, feeding into a No. 2 reaction kettle, starting stirring, controlling the temperature in the reaction kettle to be 40-45 ℃, reacting for 4 hours, stopping stirring, opening a tail gas condensation reflux device, and feeding overflowed raw material gas and non-condensable gas into a methanol falling film absorption device;

step three, carrying out heat preservation reaction, opening a discharge valve, entering a No. 3 reaction kettle, starting stirring, controlling the temperature in the reaction kettle to be 55-60 ℃, reacting for 2 hours, sampling, detecting the end point, supplementing hydrogen sulfide, continuing to react to the end point, stopping stirring, simultaneously opening a tail gas condensation reflux device, and entering overflowed feed gas and non-condensable gas into a methanol falling film absorption device;

and step four, carrying out heat preservation reaction, opening a discharge valve, feeding the mixture into a No. 4 reaction kettle, starting stirring, slowly cooling to 5-10 ℃, cooling for 3 hours, stopping stirring, opening a tail gas condensation reflux device, and feeding overflowed raw material gas and non-condensable gas into a methanol falling film absorption device.

Step five, centrifugally extracting, opening a discharge valve, feeding the obtained product into a centrifugal machine, feeding the obtained filter cake after centrifugation into a closed-loop reaction kettle, and performing closed-loop reaction by using hydrogen peroxide to obtain 3-amino-5-nitro-2, 1-benzisothiazole;

and step six, falling film absorption, wherein the filtrate from the centrifuge contains 92% of methanol, enters an absorption storage tank, is conveyed to the upper part of a falling film absorber by an absorption pump, vertically descends in a film shape along the inner wall of a tube array through a liquid phase distributor, a gas phase passes through the inner tube space from bottom to top, gas-liquid two phases carry out mass transfer on a flowing liquid film, ammonia and hydrogen sulfide in tail gas are absorbed by the methanol solution and then return to the absorption storage tank for recycling, and cooling water is introduced outside the tube array to keep the temperature in the falling film absorber at 5-10 ℃.

And seventhly, recycling, wherein 3-5% of methanol is lost in the process, supplementing 3-5% of fresh methanol, entering a falling film absorption device, mixing with the recycled methanol, absorbing ammonia and hydrogen sulfide in tail gas, and then entering a No. 1 reaction kettle.

Further, the continuous salt-free environment-friendly preparation method of scarlet powder comprises the step one of carrying out a thionation reaction on hydrogen sulfide and 2-cyano-4-nitroaniline under the action of ammonia and methanol to form a thionated product, wherein the concentration of the methanol is 98%, the concentration of the hydrogen sulfide is 99%, the thionated product is 2-amino-5-nitrothioformamide, and the feeding ratio of methanol dissolution to the thionated product is 3: 1.

Further, the continuous salt-free environment-friendly preparation method of the scarlet powder comprises a 1# reaction kettle, a 2# reaction kettle, a 3# reaction kettle and a 4# reaction kettle, and comprises a discharge valve, a stirring device, a temperature control device, a tail gas condensation reflux device and a methanol falling film absorption device, wherein the tail gas condensation reflux device is a methanol condenser.

Further, a continuous salt-free environment-friendly preparation method of scarlet powder, wherein a No. 1 reaction kettle, a No. 2 reaction kettle, a No. 3 reaction kettle and a No. 4 reaction kettle are connected in series.

Further, a continuous salt-free environment-friendly preparation method of the scarlet powder, wherein the stirring speed of the first step, the second step, the third step and the fourth step is 50-150 revolutions per minute.

Compared with the prior art, the invention has the beneficial effects that:

1. the invention adopts the 2-cyano-4-nitroaniline and the hydrogen sulfide as the raw materials, the raw materials and the product do not contain salts, the washing process is saved, the discharge of waste water is avoided, the excessive raw materials and the solvent are recycled, and the consumption and the cost are reduced.

2. The process of connecting four reaction kettles in series is adopted, so that the service time of a single reaction kettle is shortened, all equipment can be continuously used, and continuous production is realized;

3. the excessive ammonia and hydrogen sulfide are adopted as solvents to realize full circulation, and the method is safe, environment-friendly and high in utilization rate;

4. the falling film absorption is adopted, ammonia and hydrogen sulfide overflowing in the reaction are absorbed by a methanol falling film absorption device, and the absorption effect is good;

5. continuous production is adopted, and the solvent methanol lost in the reaction absorbs ammonia and hydrogen sulfide in the tail gas together with the circulating methanol, and then enters a No. 1 reaction kettle to realize recycling;

6. the yield of the thio-compound is more than or equal to 98.3 percent through recycling.

Drawings

FIG. 1 is a schematic diagram of the reaction flow of the continuous salt-free environment-friendly preparation method of scarlet powder.

FIG. 2 is a schematic diagram of the structural principle of the continuous salt-free environment-friendly preparation method of scarlet powder.

As shown in the figure: 1.1# reaction kettle; 2.2# reaction kettle, 3.3# reaction kettle, 4.4# reaction kettle, 5. closed loop reaction kettle, 6. centrifuge, 7. falling film absorption device, 8. absorption storage tank, 9. water scrubber, 11. ammonia pipeline inlet, 12.2-cyano-4-nitroaniline pipeline inlet, 13. hydrogen sulfide pipeline inlet, 14. fresh methanol inlet

Detailed Description

The present invention will be described in further detail with reference to specific embodiments below:

the method aims to solve the problems that in the existing scarlet powder production, sodium hydrosulfide and ammonium chloride or ammonium sulfate are used as raw materials, and water is needed to wash salts in a filter cake, so that a large amount of salt-containing waste liquid is generated, the treatment is difficult, methanol in the waste liquid is difficult to recover, the environmental protection requirement is not met, the yield is low, and the cost is high.

The invention provides a continuous salt-free environment-friendly preparation method of scarlet powder, which takes methanol as a solvent, ammonia, hydrogen sulfide and 2-cyano-4-nitroaniline as raw materials, realizes continuous production by connecting 4 reaction kettles in series, and has the advantages of simple process, environment protection and high yield.

In order to solve the technical problems, the technical scheme provided by the invention is as follows: