Recovery method of sulfolane waste liquid

Abstract

The invention relates to the technical field of waste liquid recovery, in particular to a method for recovering sulfolane waste liquid. The method comprises the following steps: step 1, carrying out suction filtration on the sulfolane wastewater, and evaporating out water from the sulfolane wastewater after suction filtration until no water is evaporated out, so as to obtain a first sulfolane mixed solution; 2, adding toluene into the first sulfolane mixed solution, stirring, and carrying out suction filtration to obtain a first filtrate, and 3, adding calcium oxide into the first filtrate, and carrying out stirring reflux to obtain a second sulfolane mixed solution; 4, the second sulfolane mixed solution is subjected to suction filtration to obtain a second filtrate, the second filtrate is subjected to reduced pressure distillation to remove methylbenzene, the obtained residual solution is sulfolane, the sulfolane is used for producing chlorpyridazinone, p-toluenesulfonic acid and urea, the sulfolane wastewater is generated after chlorpyridazinone, p-toluenesulfonic acid and urea are used for producing chlorpyridazinone, p-toluenesulfonic acid and urea are used for producing chlorpyridazinone, p-toluenesulfonic acid and urea are used for producing chlorpyridazinone, p-toluenesulfonic acid and urea. The recycling method can be used for efficiently recycling the sulfolane wastewater for producing chlorpheniramine, so that the recycled sulfolane solution can be repeatedly utilized.

Description

Technical Field

[0001] The present invention relates to the technical field of waste liquid recovery, and particularly relates to a method for recovering sulfolane waste liquid. Background Art

[0002] Chloridazon is a selective systemic herbicide. After spraying, it can be quickly absorbed by the roots of plants and transported to various parts of the plants. After being absorbed by the young buds and roots of weeds, it is conducted to the stems and leaves, causing the weeds to die. It is most sensitive to broad-leaved weeds before the 3-4 leaf stage, harmless to resistant crops such as sugar beets, and can effectively control annual broad-leaved weeds in sugar beet, tomato, cucumber, carrot, and cabbage fields, having broad application and market prospects.

[0003] Currently, there are mainly two process routes for synthesizing chloridazon. Route one uses 4,5-dichloropyridazin-3(2H)-one, lead acetate, zinc chloride, etc. as raw materials, and through a catalytic reaction, 1-phenyl-4,5-dichloro-6-pyridazinone is obtained, and then it reacts with ammonia through a substitution reaction to synthesize chloridazon. Heavy metals are used in this route, and the reaction yield is relatively low. Route two uses mucochloric acid, phenylhydrazine, etc. as raw materials, and through a ring-closure reaction, 1-phenyl-4,5-dichloro-6-pyridazinone is obtained, and then it reacts with ammonia through a substitution reaction to synthesize chloridazon. The process operation of this route is relatively simple, and the yield is relatively high.

[0004] In the new process for synthesizing chloridazon, dichloropyridazinone, p-toluenesulfonic acid, and urea are used as raw materials, and sulfolane is used as a solvent. However, the price of sulfolane is relatively high, reaching 20,000 yuan per ton. Therefore, realizing the recycling of sulfolane is of great significance for reducing production costs and promoting the industrial application of the new synthesis process. Summary of the Invention

[0005] The purpose of the present invention is to avoid the deficiencies in the prior art and provide a method for recovering sulfolane waste liquid, which can efficiently recover the sulfolane wastewater used in the production of chloridazon, so that the recovered sulfolane solution can be reused.

[0006] To achieve the above purpose, the present invention provides the following technical solutions:

[0007] A method for recovering sulfolane waste liquid is provided, including the following steps:

[0008] Step one: Filter the sulfolane wastewater by suction, and evaporate the water from the filtered sulfolane wastewater until no water is evaporated, obtaining a first sulfolane mixture;

[0009] Step two: Add toluene to the first sulfolane mixture and stir, and then filter by suction to obtain a first filtrate.

[0010] Step three: Add calcium oxide to the first filtrate and stir and reflux to obtain a second sulfolane mixture;

[0011] Step 4. Filter the second sulfolane mixture by suction to obtain a second filtrate. Distill toluene from the second filtrate under reduced pressure. The resulting residue is sulfolane, and the sulfolane is used for the production of chloridazon.

[0012] Wherein, the sulfolane wastewater is the sulfolane wastewater generated after the production of chloridazon from chloridazone, p-toluenesulfonic acid, and urea.

[0013] In some embodiments, in Step 2, the volume ratio of toluene to the first sulfolane mixture is 1:5 - 6.

[0014] In some embodiments, in Step 3, the weight ratio of calcium oxide to the sulfolane wastewater is 1:10 - 12.

[0015] In some embodiments, in Step 1, water is distilled off under reduced pressure using a water pump.

[0016] In some embodiments, in Step 1, water is distilled off at 100 °C under reduced pressure using a water pump.

[0017] In some embodiments, in Step 3, the time for stirring and refluxing is 40 - 80 min.

[0018] Advantages of the method for recycling sulfolane waste liquid of the present invention:

[0019] For the method for recycling sulfolane waste liquid of the present invention, water in the sulfolane wastewater is initially distilled off by distillation to obtain a first sulfolane mixture. Subsequently, toluene is used to extract the first sulfolane mixture to remove nitrogen-containing substances such as urea and p-toluenesulfonamide. Then, the first filtrate is obtained through suction filtration. After adding calcium oxide to the first filtrate, stirring and refluxing are carried out for dehydration. Adding calcium oxide for reflux dehydration can remove water more thoroughly. Among them, the method of adding calcium oxide for reflux dehydration can achieve dehydration more efficiently, ensuring that the recycled sulfolane can be used again for the production of chloridazon. After dehydration and suction filtration again, toluene is then distilled off, and the resulting residue is sulfolane. The recycled sulfolane is close to pure sulfolane and can be used for the efficient and repeated production of chloridazon. This recycling method solves the problem of sulfolane discharge, and can reuse sulfolane, which is beneficial to reducing the production cost of chloridazon and more conducive to promoting the large-scale application of new chloridazon processes. Specific Embodiments

[0020] The following will refer to the preferred embodiments of the present invention. Although the preferred embodiments are presented, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to make the present invention more thorough and complete, and to be able to fully convey the scope of the present invention to those skilled in the art.

[0021] Example 1

[0022] To illustrate the origin of the sulfolane waste liquid of the present invention, the following process for preparing metribuzin is described:

[0023] In the new process for synthesizing metribuzin, 4,6-dichloropyridazin-3(2H)-one, p-toluenesulfonic acid, and urea are used as raw materials, and sulfolane is used as a solvent. To fully illustrate the new process for synthesizing metribuzin, the synthesis process of the new metribuzin synthesis is exemplarily disclosed: In a 2000 ml three-necked flask, 410 g (1.65 mol, 97.5%) of 4,6-dichloropyridazin-3(2H)-one, 323 g (1.70 mol) of p-toluenesulfonic acid, 204 g (3.4 mol) of urea, and 700 ml of sulfolane are added respectively, and the temperature is raised to 160-170 °C. Stir and react for 3 h, then add 204 g (3.4 mol) of urea to the reaction system, and continue to stir and react at this temperature until thin plate analysis shows that the raw materials disappear, and the total reaction time is 7 h.

[0024] The reaction system is cooled to room temperature, and the reaction mixture is poured into 1500 ml of water. A large amount of white solid precipitates. After stirring for 2 h, suction filtration is carried out, washed with water, and dried to obtain 321 g of crude metribuzin with a content of 88.5%.

[0025] Although the above can obtain a good recovery rate of metribuzin, however, the price of sulfolane is relatively high, reaching 20,000 yuan / ton. Therefore, it is necessary to realize the recycling of sulfolane.

[0026] In this regard, this embodiment discloses a method for recycling sulfolane waste liquid, including the following steps:

[0027] Step 1: Filter the sulfolane wastewater by suction filtration to evaporate the water from the filtered sulfolane wastewater until no water is evaporated, and obtain a first sulfolane mixture;

[0028] Step 2: Add toluene to the first sulfolane mixture and stir, and then filter by suction to obtain a first filtrate.

[0029] Step 3: Add calcium oxide to the first filtrate and stir and reflux to obtain a second sulfolane mixture;

[0030] Step 4: Filter the second sulfolane mixture by suction to obtain a second filtrate. Distill off toluene from the second filtrate under reduced pressure, and the resulting residue is sulfolane, and the sulfolane is used for the production of metribuzin.

[0031] Wherein, the sulfolane wastewater is the sulfolane wastewater generated after the production of chloridazon, p-toluenesulfonic acid, and urea to produce metribuzin.

[0032] The above method for recycling sulfolane waste liquid preliminarily evaporates the water in the sulfolane wastewater by distillation to obtain a first sulfolane mixture, and then uses toluene to extract the first sulfolane mixture to remove nitrogen-containing substances such as urea and p-toluenesulfonamide. Subsequently, suction filtration is performed to obtain a first filtrate. After adding calcium oxide to the first filtrate, stirring and refluxing for dehydration are carried out. Adding calcium oxide and refluxing for dehydration can more thoroughly remove water. Among them, the method of adding calcium oxide and refluxing for dehydration can more efficiently achieve dehydration, ensuring that the recycled sulfolane can be used again in the production of chloridazon. After dehydration and suction filtration again, toluene is then evaporated, and the resulting residual liquid is sulfolane. The recycled sulfolane is close to pure sulfolane and can be used for the efficient and repeated production of chloridazon. This recycling method solves the problem of sulfolane discharge, can reuse sulfolane, is beneficial to reducing the production cost of chloridazon, and is more conducive to promoting the large-scale application of new chloridazon processes.

[0033] In this embodiment, in step two, the volume ratio of the toluene to the first sulfolane mixture is 1:5 to 6, preferably 1:5.5.

[0034] In this embodiment, in step three, the weight ratio of the calcium oxide to the sulfolane wastewater is 1:10 to 12, preferably 1:11. In this embodiment, in step one, a water pump is used to evaporate water under reduced pressure.

[0035] In this embodiment, in step one, water is evaporated at 100 °C under reduced pressure by a water pump.

[0036] In this embodiment, in step three, the stirring and refluxing time is 40 to 80 min, preferably 60 minutes.

[0037] Experimental process

[0038] To further illustrate the experimental process of the present invention, the following experiments are carried out.

[0039] Using dichloropyridazinone, p-toluenesulfonic acid, and urea as raw materials, cyclopentane as solvent, the waste water after the reaction is the waste liquid of cyclopentane. For this, most of the water is first evaporated. In order to further remove the residues of dichloropyridazinone, p-toluenesulfonic acid, and urea in the waste liquid, the waste liquid is extracted with toluene to obtain a toluene solution containing cyclopentane. For this, the toluene solution is first separated and then toluene is evaporated, and the remaining is the recovered cyclopentane. The recovered cyclopentane is reused to synthesize the product. However, the crude product content obtained by the synthesis of the recovered cyclopentane is relatively low, below 75%. And the yield is below 65%, which is still relatively low (about 65%). The analysis results show that the cyclopentane recovered by this method has a much higher by-product content of the product. The invention adds an operation of dehydrating again after adding calcium chloride in the experimental link of recovering sulfolane, that is, after distilling water from sulfolane-containing wastewater, extracting with toluene, adding calcium oxide to the obtained toluene solution, stirring and refluxing for dehydration for 30 minutes, and achieving the requirements that cannot be achieved by the conventional reflux dehydration method by adding calcium oxide and stirring and refluxing for dehydration, and filtering and distilling toluene from the filtrate, the residual liquid is sulfolane. The recovery rate of sulfolane by this method is 75-80%, and the sulfolane dehydrated by calcium oxide is used for the synthesis of products, and the quality of the obtained products is similar to that of fresh sulfolane as a solvent.

[0040] Specific experimental example:

[0041] In the new process for synthesizing chlorpyrifos, dichloropyridazinone, p-toluenesulfonic acid, and urea are used as raw materials, and sulfolane is used as a solvent. In order to fully illustrate the new process for synthesizing chlorpyrifos and the recovery process of its waste liquid, the new process for synthesizing chlorpyrifos is disclosed as an example: 410 grams (1.65 mol, 97.5%) of dichloropyridazinone, 323 grams (1.70 mol) of p-toluenesulfonic acid, 204 grams (3.4 mol) of urea and 700 ml of sulfolane are added to a 2000 ml three-necked bottle, and the temperature is heated to 160-170° C. The reaction is stirred for 3 hours, and then 204 grams (3.4 mol) of urea is added to the reaction system, and the reaction is continued to be stirred at this temperature until the thin plate analysis shows that the raw materials disappear, and the total reaction time is 7 hours.

[0042] Sulfolane wastewater recycling and treatment steps:

[0043] After the filtration, the sulfolane wastewater is evaporated under reduced pressure by a water pump until no water is evaporated under reduced pressure at about 100°C. After adding 600ml of toluene and stirring for 30min, the filter is filtered and the filter residue is about 500g. After adding 100g of calcium oxide, the filtrate is stirred and refluxed for 1 hour, filtered, and the filtrate is decompressed to evaporate toluene. The residual liquid is sulfolane, about 600ml, which can be used repeatedly for the synthesis of chlorpyrifos. The recovery rate is about 85%.

[0044] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for recycling sulfolane waste liquid, characterized in that, It includes the following steps: Step 1: Filter the sulfolane wastewater by suction filtration, and evaporate the water from the filtered sulfolane wastewater until no water is evaporated, obtaining a first sulfolane mixture; Step 2: Add toluene to the first sulfolane mixture and stir, then filter by suction to obtain a first filtrate; Step 3: Add calcium oxide to the first filtrate and stir and reflux to obtain a second sulfolane mixture; Step 4: Filter the second sulfolane mixture by suction to obtain a second filtrate, distill off toluene from the second filtrate under reduced pressure, and the resulting residue is sulfolane, and the sulfolane is used for the production of chloridazon; Wherein, the sulfolane wastewater is the sulfolane wastewater generated after the production of chloridazon from chlorodazinone, p-toluenesulfonic acid, and urea.

2. The method for recycling sulfolane waste liquid according to claim 1, wherein In Step 2, the volume ratio of the toluene to the first sulfolane mixture is 1:5 - 6.

3. The method for recycling sulfolane waste liquid according to claim 1, characterized in that, In Step 3, the weight ratio of the calcium oxide to the sulfolane wastewater is 1:10 - 12.

4. The method for recycling sulfolane waste liquid according to claim 1, characterized in that, In Step 1, a water pump is used to evaporate water under reduced pressure.

5. The recovery method of sulfolane waste liquid according to claim 4, characterized in that, In Step 1, water is evaporated at 100 °C under reduced pressure by a water pump.

6. The recovery method of sulfolane waste liquid according to claim 1, wherein In Step 3, the stirring and reflux time is 40 - 80 min.