Method for recovering ammonium sulfate from pyprioffine intermediate aldehyde pyridine wastewater

Abstract

The present application belongs to the technical field of wastewater treatment, and particularly relates to a method for recovering ammonium sulfate from aldehyde pyridine intermediate aldehyde pyridine wastewater. Dichloromethane is added to the aldehyde pyridine liquid, and the obtained ammonium acetate wastewater is extracted again with dichloromethane. The extracted ammonium acetate wastewater is subjected to light component removal under reduced pressure, and the water phase after light component removal is added with activated carbon. After stirring, the activated carbon is filtered out. Concentrated sulfuric acid is added dropwise to the water phase, and then the temperature is increased and the water phase is distilled under reduced pressure. Then the temperature is decreased, and the filter cake is washed with saturated ammonium sulfate aqueous solution. After drying, ammonium sulfate salt is obtained. The intermediate aldehyde pyridine is separated out, the intermediate wastewater is treated separately to recover ammonium sulfate, and the treatment process is avoided to be complicated due to impurities in the pymetrozine technical material wastewater. Meanwhile, economic benefits are generated by recovering ammonium sulfate. The ammonium sulfate recovered from the wastewater meets the national standard GB / T535-2020 for fertilizer-grade ammonium sulfate.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment technology, specifically relating to a method for recovering ammonium sulfate from pymetrozine intermediate aldehyde pyridine wastewater. Background Technology

[0002] Pymetrozine belongs to the pyridine (pyridine-imino) or triazinone class of insecticides. It is a non-bacterial insecticide that exhibits excellent control effects against piercing-sucking pests on various crops. The existing method for synthesizing pymetrozine involves first using cyanopyridine as a raw material and water as a solvent for hydrogenation reduction to synthesize the intermediate aldehyde pyridine. The aldehyde pyridine intermediate is then directly reacted with aminotriazinone hydrochloride in the entire batch of feed solution under alkali conditions to synthesize pymetrozine. Filtration yields solid pymetrozine and mother liquor wastewater. During the synthesis of aldehyde pyridine, salts and wastewater are generated without treatment and are directly incorporated into the pymetrozine reaction process.

[0003] Therefore, during the preparation process, the synthesis of the intermediate aldehyde pyridine produces ammonium acetate as a byproduct. Since the solvent is water, this generates ammonium acetate brine, which is directly incorporated into the pymetrozine mother liquor wastewater. This brine contains both ammonium acetate and sodium chloride, leading to a complex and costly treatment process for pymetrozine technical wastewater. Therefore, pre-treating the aldehyde pyridine feed solution would simplify the composition of the pymetrozine technical wastewater.

[0004] Summary of the Invention

[0005] The purpose of this invention is to provide a method for recovering ammonium sulfate from pymetrozine intermediate aldehyde wastewater.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A method for recovering ammonium sulfate from pymetrozine intermediate aldehyde pyridine wastewater involves adding dichloromethane to an aldehyde pyridine feed solution, extracting it to obtain an aldehyde pyridine dichloromethane solution and ammonium acetate wastewater; adding dichloromethane again to the ammonium acetate wastewater for extraction, removing light components from the extracted ammonium acetate wastewater under reduced pressure, adding activated carbon to the aqueous phase after light component removal, stirring and filtering out the activated carbon, adding concentrated sulfuric acid dropwise to the aqueous phase, then heating and distilling under reduced pressure, then cooling and filtering, washing the filter cake with a saturated ammonium sulfate aqueous solution, and drying the filter cake to obtain ammonium sulfate salt.

[0008] The aldehyde pyridine feed solution is synthesized by hydrogenation reduction of cyanopyridine as a raw material and water as a solvent to form the intermediate aldehyde pyridine. The feed solution includes the byproduct ammonium acetate.

[0009] The pressure reduction and light removal conditions are: -90 kPa / 44~46℃ at the top of the tower.

[0010] The heating and vacuum distillation conditions are: -90 kPa / 53~55℃.

[0011] The activated carbon accounts for 1% to 2% of the mass of the liquid feed.

[0012] Furthermore, activated carbon is added to the aqueous phase after light removal, and the mixture is stirred at 20–40°C for 2–4 hours.

[0013] The ratio of dichloromethane to aldehyde pyridine solution is 20-50%.

[0014] The ratio of dichloromethane to ammonium acetate wastewater is 20-50%.

[0015] Furthermore, the ammonium acetate wastewater is extracted 1-3 times with dichloromethane.

[0016] Furthermore, the filter cake is washed 2-5 times with a saturated ammonium sulfate aqueous solution.

[0017] The superior effects achieved by this invention compared to existing technologies:

[0018] (1) After the synthesis of the intermediate aldehyde pyridine, this invention separates the intermediate aldehyde pyridine and treats the intermediate wastewater separately to recover ammonium sulfate. This avoids the complex treatment process caused by impurities in the wastewater of pymetrozine technical grade, while also generating economic benefits from the recovery of ammonium sulfate. The ammonium sulfate recovered from the wastewater by this invention is analyzed according to the national standard GB / T535-2020 and meets the requirements for fertilizer-grade ammonium sulfate.

[0019] (2) The intermediate wastewater of the present invention is treated separately, which simplifies the composition of the pymetrozine technical wastewater.

[0020] (3) The synthesis method of the present invention is suitable for large-scale industrial production. Detailed Implementation

[0021] The following describes in detail the specific embodiments of the technical solution of the present invention, but the present invention is not limited to the following description.

[0022] Example 1

[0023] The preparation method of aldehyde pyridine solution is as follows: 200g of water, 69g of glacial acetic acid, 120g of 3-cyanopyridine and 5g of catalyst are added to a high-pressure reactor; hydrogen is introduced, pressure is 0.2MPa, temperature is 20-30℃, and the temperature is maintained for 6h. After the reaction is completed, the material in the reactor is discharged.

[0024] Example 2

[0025] 400g of the aldehyde-pyridine feed solution prepared in Example 1 was added to a 1000ml four-necked flask, along with 120g of dichloromethane. The mixture was stirred for 20 minutes, allowed to stand and separate into layers, yielding a dichloromethane solution of aldehyde-pyridine and ammonium acetate wastewater. The ammonium acetate wastewater was further extracted twice with 120g of dichloromethane. The aqueous phase after three extractions was then subjected to vacuum distillation to remove light components until the solution reached -90kPa / 44~46℃ at the top of the column. 4g of activated carbon was added to the aqueous phase after light component removal, and the mixture was stirred at 30℃ for 2 hours. The activated carbon was then filtered out, and 70.5g of concentrated sulfuric acid was added dropwise to the aqueous phase. The mixture was then heated and distilled under reduced pressure until it reached -90kPa / 53~55℃. Distillation was then stopped, the temperature was lowered, and the mixture was filtered. The filter cake was washed three times with a saturated ammonium sulfate aqueous solution and dried to obtain ammonium sulfate salt. According to the national standard GB / T535-2020, the solution met the requirements for fertilizer-grade ammonium sulfate.

[0026] Example 3

[0027] 4 kg of the aldehyde-pyridine feed solution prepared in Example 1 was added to a 10 L reactor, along with 1.6 kg of dichloromethane. The mixture was stirred for 20 minutes, allowed to stand and separate into layers, yielding a dichloromethane solution of aldehyde-pyridine and ammonium acetate wastewater. The ammonium acetate wastewater was further extracted twice with 1.6 kg of dichloromethane. The aqueous phase after three extractions was then subjected to vacuum distillation to remove light components until the solution reached -90 kPa / 44–46 °C at the top of the column. 40 g of activated carbon was added to the aqueous phase after light component removal, and the mixture was stirred at 25 °C for 4 hours. The activated carbon was then filtered out, and 705 g of concentrated sulfuric acid was added dropwise to the aqueous phase. The mixture was then heated and distilled under reduced pressure until it reached -90 kPa / 53–55 °C. Distillation was then stopped, the temperature was lowered, and the mixture was filtered. The filter cake was washed three times with a saturated ammonium sulfate aqueous solution and dried to obtain ammonium sulfate salt. According to the national standard GB / T535-2020, the solution met the requirements for fertilizer-grade ammonium sulfate.

[0028] Comparative Example 1

[0029] 400g of the aldehyde pyridine feed solution prepared in Example 1 was added to a 1000ml four-necked flask, along with 120g of ethyl acetate. The mixture was stirred for 20 minutes, allowed to stand and separate into layers, yielding an ethyl acetate solution of aldehyde pyridine and ammonium acetate wastewater. The ammonium acetate wastewater was further extracted four times with 120g of ethyl acetate. After five extractions, the aqueous phase was subjected to vacuum distillation to remove light components until the temperature reached -90kPa / 44-46℃ at the top of the column. 4g of activated carbon was added to the aqueous phase after light component removal, and the mixture was stirred at 20-40℃ for 2 hours. The activated carbon was then filtered out, and 70.5g of concentrated sulfuric acid was added dropwise to the aqueous phase. The mixture was then heated and distilled under reduced pressure until the temperature reached -90kPa / 53-55℃. Distillation was then stopped, the temperature was lowered, and the mixture was filtered. The filter cake was washed three times with a saturated ammonium sulfate aqueous solution and dried to obtain ammonium sulfate salt. The ammonium sulfate salt was irritating, and a small amount of aldehyde pyridine residue was detected.

[0030] Comparative Example 2

[0031] 400g of the aldehyde-pyridine feed solution prepared in Example 1 was added to a 1000ml four-necked flask, along with 120g of dichloromethane. The mixture was stirred for 20 minutes, allowed to stand and separate into layers, yielding a dichloromethane solution of aldehyde-pyridine and ammonium acetate wastewater. The ammonium acetate wastewater was further extracted twice with 120g of dichloromethane each time. After three extractions, the aqueous phase was removed from the light phase under reduced pressure in a column until the temperature reached -90kPa / 44~46℃ at the top of the column. 70.5g of concentrated sulfuric acid was added dropwise to the aqueous phase after the light phase removal, and the temperature was raised and the mixture was distilled under reduced pressure until the temperature reached -90kPa / 53~55℃. Distillation was then stopped, the temperature was lowered, and the mixture was filtered. The filter cake was washed three times with a saturated ammonium sulfate aqueous solution and dried to obtain ammonium sulfate salt, which was blackish-gray in appearance.

[0032] As can be seen from the comparative examples and the embodiments, the ammonium sulfate salt obtained by extraction with ethyl acetate in the comparative examples does not meet the requirements for fertilizer-grade ammonium sulfate. The present invention recovers fertilizer-grade ammonium sulfate from aldehyde pyridine wastewater, which significantly reduces the overall production cost. Moreover, the separate treatment of aldehyde pyridine wastewater simplifies the composition of pymetrozine technical wastewater and creates better conditions for the industrial-scale production of the product.

[0033] The above examples are merely illustrative of the technical concept and features of the present invention and should not be construed as limiting the scope of protection of the present invention. All equivalent transformations or modifications made in accordance with the essence of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for recovering ammonium sulfate from pymetrozine intermediate aldehyde wastewater, characterized in that: Dichloromethane was added to the aldehyde pyridine feed solution for extraction. The resulting ammonium acetate wastewater was then extracted with dichloromethane 1-3 times. The extracted ammonium acetate wastewater was then de-lightened under reduced pressure. Activated carbon was added to the aqueous phase after de-lightening, and the mixture was stirred at 20-40°C for 2-4 hours. After stirring, the activated carbon was filtered out. Concentrated sulfuric acid was added dropwise to the aqueous phase, and the mixture was then heated and distilled under reduced pressure. The mixture was then cooled and filtered. The filter cake was washed with a saturated ammonium sulfate aqueous solution. After drying the filter cake, ammonium sulfate salt was obtained. The amount of dichloromethane used is 20-50% of the mass of the aldehyde-pyridine solution.

2. The method for recovering ammonium sulfate from pymetrozine intermediate aldehyde wastewater according to claim 1, characterized in that: The aldehyde pyridine feed solution is synthesized by hydrogen reduction of cyanopyridine as a raw material and water as a solvent to form the intermediate aldehyde pyridine. The feed solution includes the byproduct ammonium acetate.

3. The method for recovering ammonium sulfate from pymetrozine intermediate aldehyde wastewater according to claim 1, characterized in that: The pressure reduction and light removal conditions are: -90 kPa / 44~46℃ at the top of the tower.

4. The method for recovering ammonium sulfate from pymetrozine intermediate aldehyde wastewater according to claim 1, characterized in that: The heating and vacuum distillation conditions are: -90 kPa / 53~55℃.

5. The method for recovering ammonium sulfate from pymetrozine intermediate aldehyde wastewater according to claim 1, characterized in that: The mass of the activated carbon is 1% to 2% of the mass of the liquid feed.

6. The method for recovering ammonium sulfate from pymetrozine intermediate aldehyde wastewater according to claim 1, characterized in that: The dosage of dichloromethane is 20-50% of the mass of ammonium acetate wastewater.

7. The method for recovering ammonium sulfate from pymetrozine intermediate aldehyde wastewater according to claim 1, characterized in that: Wash the filter cake 2-5 times with a saturated ammonium sulfate aqueous solution.

Images