CN108299306B - Tail gas treatment process in synthesis process of bromochlorohydantoin - Google Patents
Tail gas treatment process in synthesis process of bromochlorohydantoin Download PDFInfo
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- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D233/00—Heterocyclic compounds containing 1,3-diazole or hydrogenated 1,3-diazole rings, not condensed with other rings
- C07D233/54—Heterocyclic compounds containing 1,3-diazole or hydrogenated 1,3-diazole rings, not condensed with other rings having two double bonds between ring members or between ring members and non-ring members
- C07D233/66—Heterocyclic compounds containing 1,3-diazole or hydrogenated 1,3-diazole rings, not condensed with other rings having two double bonds between ring members or between ring members and non-ring members with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. ester or nitrile radicals, directly attached to ring carbon atoms
- C07D233/72—Two oxygen atoms, e.g. hydantoin
- C07D233/80—Two oxygen atoms, e.g. hydantoin with hetero atoms or acyl radicals directly attached to ring nitrogen atoms
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Abstract
The invention relates to a tail gas treatment process in a synthesis process of bromochlorohydantoin, which comprises the following steps of 1, preparing the bromochlorohydantoin in a synthesis kettle by taking 5, 5-dimethylhydantoin as a raw material; introducing tail gas of the synthesis kettle into a tail gas absorption kettle, and emptying the tail gas absorption kettle through an environment-friendly absorption tower; a tail gas absorption liquid which is a mixed liquid of an aqueous solution of 5, 5-dimethylhydantoin and sodium hydroxide or a dibromohydantoin mother liquid of 5, 5-dimethylhydantoin and sodium hydroxide is arranged in the tail gas absorption kettle; the environment-friendly absorption tower is internally provided with leaching absorption liquid which is a sodium hydroxide aqueous solution or a mixture of sodium hydroxide and a dibromo hydantoin mother liquor; 2. and after the synthesis kettle is empty, transferring the tail gas absorption liquid in the tail gas absorption kettle into the synthesis kettle, transferring the leaching absorption liquid in the environment-friendly absorption tower into the tail gas absorption kettle, and adding 5, 5-dimethyl hydantoin. The invention ensures that the tail gas generated in the synthesis process of the bromochlorohydantoin is absorbed by the tail gas absorption kettle and the environment-friendly absorption tower in two stages, thereby meeting the requirement of environment-friendly emission.
Description
Technical Field
The invention belongs to the field of organic synthesis, and particularly relates to a tail gas treatment process in a bromine-chlorine hydantoin synthesis process.
Background
Bromochlorohydantoin, known collectively as 1-bromo-3-chloro-5, 5-dimethylhydantoin; 1-bromo-3-chloro-5, 5-dimethylhydantoin, as a white or off-white crystalline powder, with a slightly chlorine odor, is soluble in benzene, dichloromethane and chloroform, and can be further processed into granules and tablets. The bromochloro-sea integrates the sterilization advantages of bromochloro because of the new generation of oxidation type disinfectant, has the characteristics of high stability, small smell, stronger sterilization effect, slow release, long lasting effectiveness and the like compared with other chlorine preparations, and can be widely used for: sterilizing and disinfecting swimming pools and drinking water; disinfecting the water body in the aquaculture industry; sterilizing and algae removing industrial circulating cooling water; the environment of public places such as hotels, hospitals and the like is disinfected. At present, the enterprises in China produce the bromochlorohydantoin, mainly take 5, 5-dimethylhydantoin, sodium hydroxide, bromine or dibromohydantoin mother liquor (sodium bromide aqueous solution) and chlorine as raw materials, and adopt a public method such as CN 103333115A; CN 101103723A; CN1611492A and the like,
the chemical reaction formula is as follows:
synthesizing the bromochlorohydantoin in an enamel reaction kettle at a certain temperature. Any one of the above methods for synthesizing bromochlorohydantoin, the method for treating the synthesis tail gas containing chlorine, is to directly introduce the synthesis tail gas into an environment-friendly spray tower, absorb chlorine with alkali liquor and then evacuate, thereby generating a large amount of tail gas absorption waste liquid, being not beneficial to environmental protection and simultaneously increasing the production cost.
Disclosure of Invention
The invention aims to provide a tail gas treatment process in the synthesis process of bromochlorohydantoin, and after the tail gas is treated by the process, no tail gas absorption waste liquid is generated any more, so that the process is beneficial to environmental protection, and meanwhile, chlorine in the tail gas is reused, so that the utilization rate of the chlorine is improved, and the cost is reduced.
In order to achieve the above object, the present invention provides a tail gas treatment process in a synthesis process of bromochlorohydantoin, which comprises the following steps,
(1) preparing bromochlorohydantoin from 5, 5-dimethylhydantoin in a synthesis kettle; introducing tail gas of the synthesis kettle into a tail gas absorption kettle, and emptying a emptying pipe of the tail gas absorption kettle through an environment-friendly absorption tower; a tail gas absorption liquid is arranged in the tail gas absorption kettle, and the tail gas absorption liquid is a water solution of 5, 5-dimethylhydantoin and sodium hydroxide or a mixed liquid of a mother solution of 5, 5-dimethylhydantoin and sodium hydroxide dibromine hydantoin;
the environment-friendly absorption tower is internally provided with eluting absorption liquid, and the eluting absorption liquid is sodium hydroxide aqueous solution or a mixture of sodium hydroxide and dibromohydantoin mother liquor;
(2) when the synthesis kettle in the step (1) completes synthesis of a batch of materials, and the kettle is empty, transferring tail gas absorption liquid in the tail gas absorption kettle into the synthesis kettle to synthesize bromochlorohydantoin, transferring leaching absorption liquid in the environment-friendly absorption tower into the tail gas absorption kettle, and adding 5, 5-dimethylhydantoin synthesized in the step (1) to be used as the tail gas absorption liquid of the tail gas absorption kettle; and (4) preparing the leaching absorption liquid in the environment-friendly absorption tower again.
Further, the synthesis method for preparing the bromochlorohydantoin in the step (1) comprises the following steps,
dissolving 5, 5-dimethylhydantoin and sodium hydroxide in water according to a conventional ratio, and carrying out bromination and chlorination reactions by using bromine and chlorine as halogenating agents;
the tail gas absorption liquid is prepared by adding 5, 5-dimethylhydantoin, sodium hydroxide and water according to a synthetic ratio;
the leaching absorption liquid is prepared by adding sodium hydroxide and water according to a synthetic ratio.
Further, in the step (2), when the synthesis kettle in the step (1) completes synthesis of a batch of materials, after the kettle is empty, tail gas absorption liquid in the tail gas absorption kettle is transferred into the synthesis kettle, bromine is dropwise added into the synthesis kettle according to the proportion in the step (1) and chlorine is introduced into the synthesis kettle to synthesize the bromochlorohydantoin again; transferring the leaching absorption liquid in the environment-friendly absorption tower into a tail gas absorption kettle, and adding 5, 5-dimethylhydantoin according to the proportion in the step (1) to be used as the tail gas absorption liquid of the tail gas absorption kettle; and (4) preparing the leaching absorption liquid in the environment-friendly absorption tower again.
Further, the synthesis method for preparing bromochlorohydantoin in step (1) comprises dissolving 5, 5-dimethylhydantoin and 15-25% sodium hydroxide of the total weight of the process proportion in water according to the conventional proportion, dropwise adding bromine and introducing chlorine into the solution, and simultaneously dropwise adding the rest sodium hydroxide aqueous solution;
the tail gas absorption liquid is a mixture of 5, 5-dimethylhydantoin prepared according to a synthesis ratio, water and sodium hydroxide accounting for 15-25% of the total weight of the process ratio;
the leaching absorption liquid is a mixture of water prepared according to a synthetic ratio and sodium hydroxide accounting for 15-25% of the total weight of the process ratio;
further, in the step (2), when the synthesis kettle in the step (1) completes synthesis of a batch of materials, and after the kettle is empty, tail gas absorption liquid in the tail gas absorption kettle is transferred into the synthesis kettle, bromine and chlorine gas are dripped into the synthesis kettle according to the proportion in the step (1), and simultaneously, 75-85% of sodium hydroxide which is remained in the total weight of the process proportion in the step (1) is dripped, so that the bromochlorohydantoin is synthesized again; meanwhile, transferring the leaching absorption liquid in the environment-friendly absorption tower into a tail gas absorption kettle, and adding the 5, 5-dimethylhydantoin synthesized in the step (1) to be used as the tail gas absorption liquid of the tail gas absorption kettle; and (4) preparing the leaching absorption liquid in the environment-friendly absorption tower again.
Further, the synthesis method for preparing bromochlorohydantoin in the step (1) comprises the steps of dissolving 5, 5-dimethylhydantoin in a mother liquor containing sodium bromide generated in the production of dibromohydantoin according to a conventional ratio, using chlorine as a halogenating agent, and simultaneously dropwise adding a sodium hydroxide solution with the mass fraction of 30-37% for bromination and chlorination reaction;
the tail gas absorption liquid is a mixture of 5, 5-dimethylhydantoin prepared according to a synthesis ratio, mother liquid containing sodium bromide and a sodium hydroxide solution with the mass fraction of 30-37 percent, wherein the mass fraction of the sodium hydroxide solution is 15-25 percent of the total weight of the process ratio;
the leaching absorption liquid is a mixture of water prepared according to a synthetic ratio and a sodium hydroxide solution with the mass fraction of 30-37% and the total weight of 15-25% of the process ratio.
Further, the mother liquor containing sodium bromide produced in the production of dibromohydantoin is: taking 5, 5-dimethylhydantoin, sodium hydroxide and bromine as raw materials, wherein the molar ratio of the raw materials is 1: (2.0-2.1): (2.0-2.2), in an aqueous solution, controlling the reaction temperature to be-5 ℃ to 35 ℃, dropwise adding bromine for bromination reaction, after the reaction is finished, centrifugally separating to remove the dibromohydantoin, and obtaining the residual liquid as the dibromohydantoin mother liquor.
Further, in the step (2), when the synthesis kettle in the step (1) completes synthesis of a batch of materials, after the kettle is empty, tail gas absorption liquid in the tail gas absorption kettle is transferred into the synthesis kettle, chlorine is introduced into the synthesis kettle, and simultaneously, sodium hydroxide solution with the mass fraction of 30-37% of the residual 75-85% of the total weight of the process proportion in the step (1) is dripped, so that bromochlorohydantoin is synthesized again; meanwhile, transferring the leaching absorption liquid in the environment-friendly absorption tower into a tail gas absorption kettle, and adding the 5, 5-dimethylhydantoin synthesized in the step (1) to be used as the tail gas absorption liquid of the tail gas absorption kettle; and (4) preparing the leaching absorption liquid in the environment-friendly absorption tower again.
Further, the pH value of the tail gas absorption liquid in the tail gas absorption kettle is above 12; and controlling the temperature of the feed liquid in the tail gas absorption kettle to be 5-15 ℃.
Further, the pH value of the leaching absorption liquid in the environment-friendly absorption tower is more than 12.
Further, the pH value of tail gas absorption liquid in the tail gas absorption kettle is 12-14;
further, the pH value of the leaching absorption liquid in the environment-friendly absorption tower is 13-14.
The invention has the following positive effects:
(1) tail gas generated in the synthesis process of the bromochlorohydantoin is absorbed by a tail gas absorption kettle and an environment-friendly absorption tower in two stages, so that the environment-friendly emission requirement is met.
(2) The tail gas absorption liquid in the tail gas absorption kettle and the leaching absorption liquid in the environment-friendly absorption tower are both used as synthesis raw materials, and are fully utilized. No tail gas absorption waste liquid is generated any more, which is beneficial to environmental protection. Meanwhile, the chlorine in the tail gas is reused, so that the utilization rate of the chlorine is improved, and the cost is reduced.
Detailed Description
The following describes embodiments of the present invention in further detail.
The present invention refers to patents CN 103333115A; CN 101103723A; the compounding ratio and technological process of synthetic bromochlorohydantoin of CN1611492A, etc.
The present invention includes the steps of, including,
(1) preparing bromochlorohydantoin from 5, 5-dimethylhydantoin in a synthesis kettle; introducing tail gas of the synthesis kettle into a tail gas absorption kettle, and emptying a emptying pipe of the tail gas absorption kettle through an environment-friendly absorption tower; a tail gas absorption liquid is arranged in the tail gas absorption kettle, and the tail gas absorption liquid is a water solution of 5, 5-dimethylhydantoin and sodium hydroxide or a mixed liquid of a mother solution of 5, 5-dimethylhydantoin and sodium hydroxide dibromine hydantoin;
the environment-friendly absorption tower is internally provided with eluting absorption liquid, and the eluting absorption liquid is sodium hydroxide aqueous solution or a mixture of sodium hydroxide and dibromohydantoin mother liquor;
(2) when the synthesis kettle in the step (1) completes synthesis of a batch of materials, and the kettle is empty, transferring tail gas absorption liquid in the tail gas absorption kettle into the synthesis kettle to synthesize bromochlorohydantoin, transferring leaching absorption liquid in the environment-friendly absorption tower into the tail gas absorption kettle, and adding 5, 5-dimethylhydantoin synthesized in the step (1) to be used as the tail gas absorption liquid of the tail gas absorption kettle; and (4) preparing the leaching absorption liquid in the environment-friendly absorption tower again.
Example 1
The synthesis of bromochlorohydantoin in this example was performed according to conventional methods. 5, 5-dimethyl hydantoin, water, sodium hydroxide, bromine and chlorine are taken as raw materials. Firstly, dissolving 5, 5-dimethylhydantoin and all sodium hydroxide in water according to a preset proportion, controlling a certain temperature, dropwise adding bromine, introducing chlorine, and carrying out bromination and chlorination reaction. And (4) carrying out centrifugal separation, washing and drying on the halogenated product to obtain the bromochlorohydantoin.
The synthetic method for preparing the bromochlorohydantoin in the step (1) comprises the following steps,
dissolving 5, 5-dimethylhydantoin and sodium hydroxide in water according to a conventional ratio, and carrying out bromination and chlorination reactions by using bromine and chlorine as halogenating agents;
the tail gas absorption liquid is prepared by adding 5, 5-dimethylhydantoin, sodium hydroxide and water according to a synthetic ratio;
the leaching absorption liquid is prepared by adding sodium hydroxide and water according to a synthetic ratio.
In the step (2), when the synthesis kettle in the step (1) completes synthesis of a batch of materials, after the kettle is empty, tail gas absorption liquid in the tail gas absorption kettle is transferred into the synthesis kettle, bromine is dropwise added into the synthesis kettle according to the proportion in the step (1) and chlorine is introduced into the synthesis kettle to synthesize the bromochlorohydantoin again; transferring the leaching absorption liquid in the environment-friendly absorption tower into a tail gas absorption kettle, and adding 5, 5-dimethylhydantoin according to the proportion in the step (1) to be used as the tail gas absorption liquid of the tail gas absorption kettle; and (4) preparing the leaching absorption liquid in the environment-friendly absorption tower again.
Specifically, the method comprises the following steps:
a. 1600kg of water is added into a 2000L enamel synthesis reaction kettle, stirring is started, the temperature of materials in the kettle is controlled to be 5-9 ℃, 120kg of 5, 5-dimethylhydantoin and 75kg of flaky sodium hydroxide are added, and stirring and dissolving are carried out. Meanwhile, the temperature of the ice brine is reduced. When the temperature of the materials in the synthesis kettle is reduced to 5 ℃, 75kg of bromine is dripped. After the completion of the dropwise addition of bromine, stirring was carried out for 15 minutes. Then the temperature of the materials in the kettle is controlled at 5-10 ℃, and 100kg of chlorine gas is introduced. After the chlorine is completely introduced, stirring for 30 minutes, centrifuging the materials, removing liquid, washing with 115kg of water, dehydrating, and drying at 50-80 ℃ to obtain 218kg of bromochlorohydantoin. The yield was 96.3%, and the content was 99.5%.
The tail gas of the reaction is introduced into a 2000L tail gas absorption kettle. The tail gas absorption liquid in the tail gas absorption kettle is as follows: 1600kg of water is added with 120kg of 5, 5-dimethylhydantoin and 75kg of sodium hydroxide and stirred to be dissolved. The temperature is controlled at 5-15 ℃. The pH value of the tail gas absorption liquid is 14.
And an emptying pipe of the tail gas absorption kettle is communicated with the environment-friendly absorption tower. The leaching absorption liquid of the environment-friendly absorption tower is as follows: 1600kg of water was added with 75kg of sodium hydroxide and dissolved by stirring. The pH value of the tail gas absorption liquid is 14.
b. In the step a, the synthesis kettle finishes discharging, after the synthesis kettle is emptied, tail gas absorption liquid in the tail gas absorption kettle is transferred to the synthesis kettle, bromine is dripped into the synthesis kettle according to the proportion in the step (1) and chlorine is introduced into the synthesis kettle to synthesize the bromochlorohydantoin again. Transferring the leaching absorption liquid in the environmental protection tower to a tail gas absorption kettle, adding 120kg of 5, 5-dimethyl hydantoin, and stirring for dissolving. The temperature is controlled at 5-15 ℃. And (d) preparing the leaching absorption liquid in the environment-friendly tower again in the same way as the case a.
In order to illustrate that the quality of the bromochlorohydantoin synthesized by using the tail gas absorption liquid in the tail gas absorption kettle is not affected. This example was further verified as follows:
when the temperature of the materials in the synthesis kettle is reduced to 5 ℃, 75kg of bromine is added dropwise. After the completion of the dropwise addition of bromine, stirring was carried out for 15 minutes. And then controlling the temperature of the materials in the kettle at 5-10 ℃, introducing 94kg of chlorine (6 kg of chlorine is absorbed by the tail gas absorption liquid and the environment-friendly absorption liquid), stirring for 30 minutes after the chlorine is introduced, centrifugally removing the liquid from the materials, washing with 115kg of water, dehydrating, and drying at 50-80 ℃ to obtain 217.5kg of bromochlorohydantoin. The yield is 96.1 percent, and the content is 99.6 percent.
c. And after the b cases are finished, repeating the b cases to obtain 218.5kg of bromochlorohydantoin with the yield of 96.5 percent and the content of 99.4 percent. The quality of the bromochlorohydantoin synthesized by using the tail gas absorption liquid in the tail gas absorption kettle is not affected.
Example 2:
the synthesis of bromochlorohydantoin in this example was performed according to conventional methods. 5, 5-dimethyl hydantoin, water, sodium hydroxide, bromine and chlorine are taken as raw materials. The synthesis method for preparing the bromochlorohydantoin in the step (1) comprises the steps of dissolving 5, 5-dimethylhydantoin and sodium hydroxide which accounts for 15-25% of the total weight of the process proportion in water according to the conventional proportion, dropwise adding bromine and chlorine into the solution, and dropwise adding the rest sodium hydroxide aqueous solution;
the tail gas absorption liquid is a mixture of 5, 5-dimethylhydantoin prepared according to a synthesis ratio, water and sodium hydroxide accounting for 15-25% of the total weight of the process ratio;
the leaching absorption liquid is a mixture of water and sodium hydroxide which is 15-25% of the total weight of the process proportion and is prepared according to the synthesis proportion.
In the step (2), when the synthesis kettle in the step (1) completes synthesis of a batch of materials, and the kettle is empty, tail gas absorption liquid in the tail gas absorption kettle is transferred into the synthesis kettle, bromine is dropwise added into the synthesis kettle according to the proportion in the step (1), and sodium hydroxide accounting for 75-85% of the total weight of the process proportion in the step (1) is dropwise added into the synthesis kettle to synthesize the bromochlorohydantoin again; meanwhile, transferring the leaching absorption liquid in the environment-friendly absorption tower into a tail gas absorption kettle, and adding the 5, 5-dimethylhydantoin synthesized in the step (1) to be used as the tail gas absorption liquid of the tail gas absorption kettle; and (4) preparing the leaching absorption liquid in the environment-friendly absorption tower again.
Specifically, the method comprises the following steps:
d. 135kg of 5, 5-dimethyl hydantoin, 50kg of 32 percent (by weight) sodium hydroxide and 1000kg of water are added into a 2000L enamel reaction kettle and stirred to be dissolved. And (3) controlling the temperature of the materials in the kettle to be 5-9 ℃, and dropwise adding 84kg of bromine. After completion of the dropwise addition of bromine, stirring was carried out for 30 minutes. Controlling the temperature to be 5-9 ℃, and introducing 113kg of chlorine. 214kg of 32 wt% sodium hydroxide solution was added dropwise with addition of bromine and chlorine. After the dropwise addition of the sodium hydroxide solution, the solution was stirred for 10 minutes, 5kg of chlorine gas was continuously introduced, and the reaction was stirred for 30 minutes. The reaction material is centrifugally dewatered, washed by 110kg of water and dried at the temperature of 60-80 ℃ to obtain 245kg of bromochlorohydantoin with the yield of 96.2 percent and the content of 99.5 percent.
And introducing the tail gas pipe of the synthesis reaction kettle into a 2000L tail gas absorption kettle. The tail gas absorption liquid in the tail gas absorption kettle is as follows: 135kg of 5, 5-dimethylhydantoin and 50kg of 32% (weight percent) sodium hydroxide solution are added into 1000kg of water and stirred to be dissolved. The temperature is controlled at 5-15 ℃. The pH value of the tail gas absorption liquid is 14.
And an emptying pipe of the tail gas absorption kettle is communicated with the environment-friendly absorption tower. The leaching absorption liquid of the environment-friendly absorption tower is as follows: 1000kg of water was added with 50kg of 32% (by weight) sodium hydroxide solution, and the mixture was dissolved by stirring. The pH value of the tail gas absorption liquid is 14.
e. d, discharging the synthesis kettle, emptying the synthesis kettle, transferring the tail gas absorption liquid in the tail gas absorption kettle to the synthesis kettle, dropwise adding bromine and introducing chlorine gas into the synthesis kettle according to the proportion in the step (1), and dropwise adding 214kg of sodium hydroxide accounting for 75-85% of the total weight of the process proportion in the step (1) to synthesize the bromochlorohydantoin again. Transferring the leaching absorption liquid in the environmental protection tower to a tail gas absorption kettle, adding 135kg of 5, 5-dimethyl hydantoin, stirring and dissolving, and using as the tail gas absorption liquid of the tail gas absorption kettle. The temperature is controlled at 5-15 ℃. And (d) preparing the leaching absorption liquid in the environment-friendly tower again.
In order to illustrate that the quality of the bromochlorohydantoin synthesized by using the tail gas absorption liquid in the tail gas absorption kettle is not affected. This example was further verified as follows:
when the temperature of the materials in the synthesis kettle is 5-9 ℃, simultaneously, 124kg of 32% (weight percentage) of sodium hydroxide solution and 84kg of bromine are added dropwise according to the proportion, (because the tail gas absorption solution and the environment-friendly leacheate contain sodium hydroxide and absorb 6kg of chlorine gas, the amount of the added sodium hydroxide solution is reduced when bromine and chlorine gas are added dropwise, and 6kg of chlorine gas is reduced), and the bromine is stirred for 30 minutes after the addition. Controlling the temperature to be 5-9 ℃, simultaneously dripping 124kg of 32 percent (weight percentage) of sodium hydroxide solution and introducing 107kg of chlorine. After the dropwise addition of the sodium hydroxide solution, the solution was stirred for 10 minutes, 5kg of chlorine gas was continuously introduced, and the reaction was stirred for 30 minutes. The reaction material is centrifugally dewatered, washed by 110kg of water and dried at the temperature of 60-80 ℃ to obtain 244.6kg of bromochlorohydantoin with the yield of 96.0 percent and the content of 99.6 percent.
f. When the example e is finished, the operation of the example e is repeated to obtain 245.2kg of bromochlorohydantoin, the yield is 96.3 percent, and the content is 99.2 percent. The quality of the bromochlorohydantoin synthesized by using the tail gas absorption liquid in the tail gas absorption kettle is not affected.
Example 3:
the synthesis of bromochlorohydantoin in this example was performed according to conventional methods. The synthesis method for preparing the bromochlorohydantoin in the step (1) comprises the steps of dissolving 5, 5-dimethylhydantoin in a mother liquor containing sodium bromide generated in the production of the dibromohydantoin according to a conventional ratio, using chlorine gas as a halogenating agent, and simultaneously dropwise adding a sodium hydroxide solution with the mass fraction of 30-37% for bromination and chlorination reaction;
the tail gas absorption liquid is a mixture of 5, 5-dimethylhydantoin prepared according to a synthesis ratio, mother liquid containing sodium bromide and a sodium hydroxide solution with the mass fraction of 30-37 percent, wherein the mass fraction of the sodium hydroxide solution is 15-25 percent of the total weight of the process ratio;
the leaching absorption liquid is a mixture of water prepared according to a synthetic ratio and a sodium hydroxide solution with the mass fraction of 30-37% and the total weight of 15-25% of the process ratio.
The mother liquor containing sodium bromide produced in the production of dibromohydantoin is: taking 5, 5-dimethylhydantoin, sodium hydroxide and bromine as raw materials, wherein the molar ratio of the raw materials is 1: (2.0-2.1): (2.0-2.2), in an aqueous solution, controlling the reaction temperature to be-5 ℃ to 35 ℃, dropwise adding bromine for bromination reaction, after the reaction is finished, centrifugally separating to remove the dibromohydantoin, and obtaining the residual liquid as the dibromohydantoin mother liquor.
In the step (2), when the synthesis kettle in the step (1) completes synthesis of a batch of materials, after the kettle is emptied, tail gas absorption liquid in the tail gas absorption kettle is transferred into the synthesis kettle, chlorine is introduced into the synthesis kettle, and simultaneously, sodium hydroxide solution with the mass fraction of 30-37 percent of the residual 75-85 percent of the total weight of the process ratio in the step (1) is dripped, so that bromochlorohydantoin is synthesized again; meanwhile, transferring the leaching absorption liquid in the environment-friendly absorption tower into a tail gas absorption kettle, and adding the 5, 5-dimethylhydantoin synthesized in the step (1) to be used as the tail gas absorption liquid of the tail gas absorption kettle; and (4) preparing the leaching absorption liquid in the environment-friendly absorption tower again.
Specifically, the method comprises the following steps:
g. 135kg of 5, 5-dimethyl hydantoin and 980kg of 11 percent (by weight) of dibromo hydantoin mother liquor are added into a 2000L enamel reaction kettle and stirred to be dissolved. Controlling the temperature of the materials in the kettle at 5-9 ℃, simultaneously dropwise adding 264kg of 32% (weight percentage) sodium hydroxide solution according to the proportion, and introducing 152kg of chlorine. After the dropwise addition of the sodium hydroxide solution, the solution was stirred for 10 minutes, 5kg of chlorine gas was continuously introduced, and the reaction was stirred for 30 minutes. The reaction material is centrifugally dewatered, washed by 110kg of water and dried at the temperature of 60-80 ℃ to obtain 245kg of bromochlorohydantoin with the yield of 96.2 percent and the content of 99.5 percent.
And introducing the tail gas pipe of the synthesis reaction kettle into a 2000L tail gas absorption kettle. The tail gas absorption liquid in the tail gas absorption kettle is as follows: 980kg of 11% (weight percent) dibromohydantoin mother liquor is added with 135kg of 5, 5-dimethylhydantoin and 50kg of 32% (weight percent) sodium hydroxide solution, and stirred and dissolved. The temperature is controlled at 5-15 ℃. The pH value of the tail gas absorption liquid is 14.
And an emptying pipe of the tail gas absorption kettle is communicated with the environment-friendly absorption tower. The leaching absorption liquid of the environment-friendly absorption tower is as follows: 980kg of 11% (weight percent) dibromohydantoin mother liquor is added with 50kg of 32% (weight percent) sodium hydroxide solution and stirred for dissolution. The pH value of the tail gas absorption liquid is 14.
h. And g, discharging the synthesis kettle in the example, emptying the synthesis kettle, transferring the tail gas absorption liquid in the tail gas absorption kettle to the synthesis kettle, introducing chlorine into the synthesis kettle, and simultaneously dropwise adding 214g of sodium hydroxide solution with the weight of 30-37% of the total weight of the process ratio in the step (1) to synthesize the bromochlorohydantoin again. Transferring the leached absorption liquid in the environmental protection tower to a tail gas absorption kettle, adding 135kg of 5, 5-dimethyl hydantoin, and stirring for dissolving. The temperature is controlled at 5-15 ℃. And (4) preparing the leaching absorption liquid in the environment-friendly tower again with the same g of the leaching absorption liquid.
In order to illustrate that the quality of the bromochlorohydantoin synthesized by using the tail gas absorption liquid in the tail gas absorption kettle is not affected. This example was further verified as follows:
the temperature of the materials in the synthesis kettle is reduced to 5-9 ℃, 214kg of 32 percent (weight percentage) sodium hydroxide solution is dripped in proportion, and 141kg of chlorine is introduced. After the dropwise addition of the sodium hydroxide solution, the solution was stirred for 10 minutes, 5kg of chlorine gas was continuously introduced, and the reaction was stirred for 30 minutes. The reaction mass is centrifuged to remove liquid, washed by 110kg of water and dried at 60-80 ℃ to obtain 245.2kg of bromochlorohydantoin with the yield of 96.3 percent and the content of 99.2 percent.
j. And after h, repeating the h operations to obtain 244.8kg of bromochlorohydantoin with the yield of 96.1 percent and the content of 99.6 percent. The quality of the bromochlorohydantoin synthesized by using the tail gas absorption liquid in the tail gas absorption kettle is not affected.
The tail gas generated in the synthesis process of the bromine-chlorine hydantoin in the invention (1) is absorbed by a tail gas absorption kettle and an environment-friendly absorption tower in two stages, thus meeting the requirement of environment-friendly emission.
(2) The tail gas absorption liquid in the tail gas absorption kettle and the leaching absorption liquid in the environment-friendly absorption tower are both used as synthesis raw materials, and are fully utilized. No tail gas absorption waste liquid is generated any more, which is beneficial to environmental protection. Meanwhile, the chlorine in the tail gas is reused, so that the utilization rate of the chlorine is improved, and the cost is reduced.
The above description is only a few examples of the present invention, and is not intended to limit the present invention. Any modification, equivalent replacement or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (6)
1. A tail gas treatment process in a synthesis process of bromochlorohydantoin is characterized in that: the method comprises the following steps of (1) preparing bromochlorohydantoin by taking 5, 5-dimethylhydantoin as a raw material in a synthesis kettle; introducing tail gas of the synthesis kettle into a tail gas absorption kettle, and emptying a emptying pipe of the tail gas absorption kettle through an environment-friendly absorption tower; a tail gas absorption liquid is arranged in the tail gas absorption kettle, and a leaching absorption liquid is arranged in the environment-friendly absorption tower; (2) when the synthesis kettle in the step (1) completes synthesis of a batch of materials, and the kettle is empty, transferring tail gas absorption liquid in the tail gas absorption kettle into the synthesis kettle to synthesize bromochlorohydantoin, transferring leaching absorption liquid in the environment-friendly absorption tower into the tail gas absorption kettle, and adding 5, 5-dimethylhydantoin synthesized in the step (1) to be used as the tail gas absorption liquid of the tail gas absorption kettle; preparing the leaching absorption liquid in the environment-friendly absorption tower again;
wherein the first synthesis method for preparing the bromochlorohydantoin in the step (1) comprises the following steps: dissolving 5, 5-dimethylhydantoin in mother liquor containing sodium bromide generated in the production of dibromohydantoin according to a conventional ratio, using chlorine as a halogenating agent, and simultaneously dropwise adding a sodium hydroxide solution with the mass fraction of 30-37% to perform bromination and chlorination reactions;
the tail gas absorption liquid is a mixture of 5, 5-dimethylhydantoin prepared according to a synthesis ratio, mother liquid containing sodium bromide and sodium hydroxide solution with the mass fraction of 30-37 percent, wherein the mass fraction of the mixture is 15-25 percent of the total weight of the process ratio, the pH value is above 12, and the temperature of the feed liquid in the tail gas absorption kettle is controlled to be 5-15 ℃; the leaching absorption liquid is a mixture of water prepared according to a synthetic ratio and a sodium hydroxide solution with the mass fraction of 30-37% and the total weight of the process ratio of 15-25%;
the mother liquor containing sodium bromide produced in the production of dibromohydantoin is: taking 5, 5-dimethylhydantoin, sodium hydroxide and bromine as raw materials, wherein the molar ratio of the raw materials is 1: (2.0-2.1): (2.0-2.2), in an aqueous solution, controlling the reaction temperature to be-5 ℃ to 35 ℃, dropwise adding bromine to carry out bromination reaction, after the reaction is finished, centrifugally separating to remove dibromohydantoin, and obtaining the residual liquid as dibromohydantoin mother liquor;
or the synthesis method II for preparing the bromochlorohydantoin in the step (1) comprises the following steps: dissolving 5, 5-dimethylhydantoin and sodium hydroxide in water according to a conventional ratio, and carrying out bromination and chlorination reactions by using bromine and chlorine as halogenating agents;
the tail gas absorption liquid is a mixture of 5, 5-dimethylhydantoin, water and sodium hydroxide which accounts for 15-25% of the total weight of the process proportion, the pH value is above 12, and the temperature of the feed liquid in the tail gas absorption kettle is controlled to be 5-15 ℃; the leaching absorption liquid is a mixture of water and sodium hydroxide which is 15-25% of the total weight of the process proportion and is prepared according to the synthesis proportion.
2. The tail gas treatment process in the synthesis process of the bromochlorohydantoin according to claim 1, wherein the tail gas treatment process comprises the following steps: in the step (2), when the synthesis kettle in the step (1) completes synthesis of a batch of materials, after the kettle is empty, tail gas absorption liquid in the tail gas absorption kettle is transferred into the synthesis kettle, bromine is dropwise added into the synthesis kettle according to the proportion in the step (1) and chlorine is introduced into the synthesis kettle to synthesize the bromochlorohydantoin again; transferring the leaching absorption liquid in the environment-friendly absorption tower into a tail gas absorption kettle, and adding 5, 5-dimethylhydantoin according to the proportion in the step (1) to be used as the tail gas absorption liquid of the tail gas absorption kettle; and (4) preparing the leaching absorption liquid in the environment-friendly absorption tower again.
3. The tail gas treatment process in the synthesis process of the bromochlorohydantoin according to claim 1, wherein the tail gas treatment process comprises the following steps: dissolving 5, 5-dimethylhydantoin and sodium hydroxide which accounts for 15-25% of the total weight of the process proportion in water according to the conventional proportion, dropwise adding bromine into the solution, introducing chlorine gas into the solution, and dropwise adding the rest sodium hydroxide aqueous solution; the tail gas absorption liquid is a mixture of 5, 5-dimethylhydantoin prepared according to a synthesis ratio, water and sodium hydroxide accounting for 15-25% of the total weight of the process ratio; the leaching absorption liquid is a mixture of water and sodium hydroxide which is 15-25% of the total weight of the process proportion and is prepared according to the synthesis proportion.
4. The tail gas treatment process in the synthesis process of the bromochlorohydantoin according to claim 3, wherein: in the step (2), in the second synthesis method, when the synthesis kettle in the step (1) completes synthesis of a batch of materials, and the kettle is empty, tail gas absorption liquid in the tail gas absorption kettle is transferred into the synthesis kettle, bromine and chlorine gas are dripped into the synthesis kettle according to the proportion in the step (1), and simultaneously, 75-85% of sodium hydroxide which is remained in the total weight of the proportion in the step (1) is dripped, so that the bromochlorohydantoin is synthesized again; meanwhile, transferring the leaching absorption liquid in the environment-friendly absorption tower into a tail gas absorption kettle, and adding the 5, 5-dimethylhydantoin synthesized in the step (1) to be used as the tail gas absorption liquid of the tail gas absorption kettle; and (4) preparing the leaching absorption liquid in the environment-friendly absorption tower again.
5. The tail gas treatment process in the synthesis process of the bromochlorohydantoin according to claim 1, wherein the tail gas treatment process comprises the following steps: in the step (2), in the first synthesis method, when the synthesis kettle in the step (1) completes synthesis of a batch of materials, after the kettle is empty, tail gas absorption liquid in the tail gas absorption kettle is transferred into the synthesis kettle, chlorine is introduced into the synthesis kettle, and simultaneously, 75-85% of sodium hydroxide solution with the mass fraction of 30-37% which is the rest of the total weight of the process proportion in the step (1) is dripped, so that bromochlorohydantoin is synthesized again; meanwhile, transferring the leaching absorption liquid in the environment-friendly absorption tower into a tail gas absorption kettle, and adding the 5, 5-dimethylhydantoin synthesized in the step (1) to be used as the tail gas absorption liquid of the tail gas absorption kettle; and (4) preparing the leaching absorption liquid in the environment-friendly absorption tower again.
6. The tail gas treatment process in the synthesis process of the bromochlorohydantoin according to claim 1, wherein the tail gas treatment process comprises the following steps: the pH value of the leaching absorption liquid in the environment-friendly absorption tower is more than 12.
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