A method and system for the preparation of a 2-acrylamido-2-methylpropane sulfonic acid salt solution having an ultra-low content of acrylonitrile

Abstract

The present application relates to the technical field of chemical synthesis, in particular to a preparation method and system of 2-acrylamido-2-methylpropanesulfonic acid salt solution with ultra-low acrylonitrile content. In the present application, the content of acrylonitrile in 2-acrylamido-2-methylpropanesulfonic acid salt solution is reduced by density difference separation, distillation and hydration reaction in turn, so that the content of acrylonitrile in the final 2-acrylamido-2-methylpropanesulfonic acid salt solution is less than 1 ppm, and 2-acrylamido-2-methylpropanesulfonic acid salt solution with ultra-low acrylonitrile content is obtained. In the present application, acrylonitrile is converted into acrylamide by hydration reaction, which not only reduces the content of acrylonitrile, but also the polymerization activity of the converted acrylamide is much greater than that of acrylonitrile, which can greatly reduce the impact on the subsequent polymerization process, has a larger adjustable range, better formula inclusiveness, and can prepare ultra-high molecular weight water-soluble polymers.

Description

Technical Field

[0001] This invention relates to the field of chemical synthesis technology, specifically to a method and system for preparing a 2-acrylamido-2-methylpropanesulfonate solution with ultra-low acrylonitrile content. Background Technology

[0002] 2-Acrylamide-2-methylpropanesulfonic acid (AMPS) is a multifunctional, water-soluble anionic monomer. It has wide applications in oilfield chemicals, water treatment agents, synthetic fibers, plastics, printing and dyeing, coatings, surfactants, antistatic agents, ceramics, photography, detergents, ion exchange resins, gas separation membranes, and the electronics industry.

[0003] 2-Acrylamido-2-methylpropanesulfonic acid is a powdery solid and a strong acid, which easily generates dust, corrodes equipment, and pollutes the environment during actual production. Liquid products overcome these drawbacks, are more convenient to use, offer higher production efficiency, and are easier to automate. Currently, 2-acrylamido-2-methylpropanesulfonic acid salt products have been developed on the market, generally prepared by neutralizing 2-acrylamido-2-methylpropanesulfonic acid powder with an alkaline substance. However, 2-acrylamido-2-methylpropanesulfonic acid powder is prepared using acrylonitrile (AN) as one of the raw materials and also as a solvent; therefore, a certain amount of acrylonitrile inevitably remains in the 2-acrylamido-2-methylpropanesulfonic acid powder.

[0004] Theoretically, while acrylonitrile can be removed by enhancing the drying effect, the drying results are often unsatisfactory due to factors such as differences in the stirring effect of the dryer and limitations in drying temperature. Furthermore, solvent encapsulation occurs during crystallization, and this form of acrylonitrile residue cannot be removed by simple drying. For these reasons, residual acrylonitrile in 2-acrylamido-2-methylpropanesulfonic acid powder is carried into the 2-acrylamido-2-methylpropanesulfonate solution product. However, the presence of acrylonitrile in the salt solution product not only negatively impacts the molecular weight and solubility of downstream polymers but also limits the application areas of sodium salts due to their toxicity, such as in coatings, daily chemicals, and pharmaceuticals. Summary of the Invention

[0005] To overcome the above problems, the present invention provides a method and system for preparing a 2-acrylamido-2-methylpropanesulfonate solution with ultra-low acrylonitrile content.

[0006] To achieve the above technical objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a method for preparing a 2-acrylamido-2-methylpropanesulfonate solution with ultra-low acrylonitrile content, comprising the following steps: The undried crude 2-acrylamido-2-methylpropanesulfonic acid was neutralized with an alkaline solution to obtain an aqueous solution of the first 2-acrylamido-2-methylpropanesulfonate; the mass fraction of acrylonitrile in the first 2-acrylamido-2-methylpropanesulfonate aqueous solution was 5-30%. The first 2-acrylamido-2-methylpropanesulfonate aqueous solution was separated into two phases by density difference, namely an acrylonitrile phase and a second 2-acrylamido-2-methylpropanesulfonate aqueous solution phase; The aqueous solution of the second 2-acrylamido-2-methylpropanesulfonate was distilled to obtain the aqueous solution of the third 2-acrylamido-2-methylpropanesulfonate. A catalyst for the hydration reaction of acrylonitrile was added to the aqueous solution of the third 2-acrylamido-2-methylpropanesulfonate, and the reaction temperature and time were controlled to obtain the aqueous solution of the fourth 2-acrylamido-2-methylpropanesulfonate. The catalyst for the acrylonitrile hydration reaction was separated by filtration of the aqueous solution of the fourth 2-acrylamido-2-methylpropanesulfonate to obtain a 2-acrylamido-2-methylpropanesulfonate solution with ultra-low acrylonitrile content, the acrylonitrile content of which was less than 1 ppm.

[0007] In one or more embodiments, the mass ratio of acrylonitrile to 2-acrylamido-2-methylpropanesulfonic acid in the undried crude 2-acrylamido-2-methylpropanesulfonic acid is (5:95) to (30:70).

[0008] In one or more embodiments, the alkali includes one of alkali metal or alkaline earth metal hydroxide, alkali metal or alkaline earth metal oxide, and ammonia. Preferably, when the alkali is an alkali metal or alkaline earth metal oxide, it can be selected from sodium hydroxide, potassium hydroxide, lithium hydroxide, magnesium hydroxide, and calcium hydroxide.

[0009] Preferably, the alkali is an alkali metal or alkaline earth metal oxide, and may be selected from sodium oxide, potassium oxide, calcium oxide and magnesium oxide.

[0010] In one or more embodiments, the mass fraction of the alkali solution is 10-50%, preferably 15-30%.

[0011] In one or more embodiments, the mass fraction of 2-acrylamido-2-methylpropanesulfonate in the first aqueous solution of 2-acrylamido-2-methylpropanesulfonate is 50-65%.

[0012] In one or more embodiments, during the neutralization reaction, the temperature is controlled at 10~30℃ and the pH value is controlled at 8.5~10.0.

[0013] In one or more embodiments, a polymerization inhibitor may be added during the neutralization reaction; Preferably, the polymerization inhibitor comprises one or more of thiazide, 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxy, phenylenediamine derivatives and mixtures thereof, or phenolic derivatives.

[0014] Preferably, the mass fraction of the polymerization inhibitor is 10~50 ppm.

[0015] In one or more embodiments, the distillation method is vacuum distillation, the vacuum degree of which is 30~150mbar; the temperature during vacuum distillation is 25~35℃.

[0016] In one or more embodiments, the catalyst for the acrylonitrile hydration reaction is a bio-enzyme catalyst; Preferably, the amount of bio-enzyme catalyst added is 0.5~4 kg / ton of acrylonitrile.

[0017] In one or more embodiments, the hydration reaction temperature is 15~25°C, the hydration reaction time is 1~4 h, and the pH during the hydration reaction is 8.5~9.5.

[0018] In one or more embodiments, an ultrafiltration membrane with a pore size of 0.005~0.05 μm is used for filtration. This ultrafiltration membrane can effectively separate catalyst macromolecules and oligomers generated during the neutralization reaction.

[0019] A second aspect of the present invention provides a system for achieving an ultra-low acrylonitrile content 2-acrylamido-2-methylpropanesulfonate solution as described in the first aspect, comprising a neutralization vessel, an oil-water separator, a distillation apparatus, a hydration vessel, and a temporary storage vessel connected in sequence. The neutralization vessel is used to neutralize undried crude 2-acrylamido-2-methylpropanesulfonic acid with alkaline solution. An oil-water separator is used to separate a first aqueous solution of 2-acrylamido-2-methylpropanesulfonate into two phases by means of density difference; The distillation apparatus was used for distilling the second 2-acrylamido-2-methylpropanesulfonate aqueous solution; The hydration reactor is used to carry out a hydration reaction of the aqueous solution of 2-acrylamido-2-methylpropanesulfonate to convert acrylonitrile into acrylamide. The temporary storage vessel is used to store a 2-acrylamido-2-methylpropanesulfonate solution with ultra-low acrylonitrile content obtained after filtering and separating the catalyst for the acrylonitrile hydration reaction.

[0020] The beneficial effects of this invention are as follows: In this invention, the acrylonitrile content in a 2-acrylamido-2-methylpropanesulfonate solution is reduced sequentially through density difference separation, distillation, and hydration reaction, resulting in a final acrylonitrile content of less than 1 ppm, thus obtaining an ultra-low acrylonitrile content 2-acrylamido-2-methylpropanesulfonate solution. This invention uses a hydration reaction to convert acrylonitrile to acrylamide, which not only reduces the acrylonitrile content but also results in acrylamide with significantly higher polymerization activity than acrylonitrile. This greatly reduces the impact on subsequent polymerization processes, allows for a wider adjustment range, better formulation compatibility, and enables the preparation of ultra-high molecular weight water-soluble polymers. Attached Figure Description

[0021] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0022] Figure 1 The image shows the liquid chromatogram of the sodium 2-acrylamido-2-methylpropanesulfonate aqueous solution with ultra-low acrylonitrile content in Example 2, where peak 4 represents acrylonitrile and peak 5 represents acrylic acid. Detailed Implementation

[0023] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0024] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0025] Inevitably, a certain amount of acrylonitrile remains in 2-acrylamido-2-methylpropanesulfonic acid powder. Theoretically, although acrylonitrile can be removed by enhancing the drying effect, the drying effect is often unsatisfactory due to factors such as differences in the stirring effect of the dryer and limitations in the drying temperature. In addition, due to solvent encapsulation during reaction crystallization, this form of acrylonitrile residue cannot be removed by simple drying. For the aforementioned reasons, the acrylonitrile residue in 2-acrylamido-2-methylpropanesulfonic acid powder is carried into the 2-acrylamido-2-methylpropanesulfonate solution product. However, the presence of acrylonitrile in the salt solution product not only negatively affects the molecular weight and solubility of downstream polymers, but also limits the application fields of sodium salt due to its toxicity, such as coatings, daily chemicals, and pharmaceuticals.

[0026] To overcome the above problems, the present invention provides a method and system for preparing a 2-acrylamido-2-methylpropanesulfonate solution with ultra-low acrylonitrile content.

[0027] This invention directly neutralizes undried crude 2-acrylamido-2-methylpropanesulfonic acid with an alkaline solution to obtain a first aqueous solution of 2-acrylamido-2-methylpropanesulfonate. Subsequently, density difference separation, distillation, and hydration reactions are performed sequentially to reduce the acrylonitrile content in the 2-acrylamido-2-methylpropanesulfonate solution. Specifically, since acrylonitrile and the aqueous solution of 2-acrylamido-2-methylpropanesulfonate are immiscible and have a significant density difference, most of the acrylonitrile can be removed by density difference separation. Distillation further reduces the acrylonitrile content, and finally, hydration converts acrylonitrile to acrylamide, further reducing the acrylonitrile content. This results in an acrylonitrile content of less than 1 ppm in the final 2-acrylamido-2-methylpropanesulfonate solution, obtaining an ultra-low acrylonitrile content 2-acrylamido-2-methylpropanesulfonate solution.

[0028] In this invention, a hydration reaction is used to convert acrylonitrile into acrylamide, which not only reduces the content of acrylonitrile, but also the polymerization activity of the converted acrylamide is much greater than that of acrylonitrile. This can significantly reduce the impact on subsequent polymerization processes, has a wider adjustment range, better formulation compatibility, and can prepare ultra-high molecular weight water-soluble polymers.

[0029] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0030] In the following examples, the biological enzyme used was acrylonitrile hydratase, and the fermentation broth was purchased from Dongying Baomo Environmental Engineering Co., Ltd.

[0031] Example 1 Figure 1The system for achieving an ultra-low acrylonitrile content 2-acrylamido-2-methylpropanesulfonate solution includes a neutralization vessel 1, an oil-water separator 2, a distillation apparatus 3, a hydration vessel 4, and a temporary storage vessel 5 connected in sequence. The neutralization vessel is used to neutralize undried crude 2-acrylamido-2-methylpropanesulfonic acid with alkaline solution. Oil-water separator 1 is used to separate the first aqueous solution of 2-acrylamido-2-methylpropanesulfonate into two phases by density difference; Distillation apparatus 2 is used for distilling the second 2-acrylamido-2-methylpropanesulfonate aqueous solution; Hydration reactor 3 is used for the hydration reaction of aqueous solution of third 2-acrylamido-2-methylpropanesulfonate to convert acrylonitrile into acrylamide; Temporary storage vessel 4 is used to store a 2-acrylamido-2-methylpropanesulfonate solution with ultra-low acrylonitrile content obtained after filtering and separating the catalyst for the acrylonitrile hydration reaction.

[0032] The undried crude 2-acrylamido-2-methylpropanesulfonic acid is transported into the neutralization vessel 1 by one of the following methods: pneumatic conveying, belt conveying, spiral conveying, pipeline conveying, or tubular chain conveying.

[0033] An overflow port is provided at the top of the neutralization vessel 1, enabling continuous reaction and improving reaction efficiency. Furthermore, the neutralization vessel 1 is equipped with a temperature sensor and a pH sensor; a cooling unit is also installed inside the neutralization vessel 1.

[0034] Oil-water separator 2 includes gravity type, centrifugal type and coalescing type oil-water separator.

[0035] The distillation apparatus 3 includes a membrane evaporator, a rising film evaporator, a scraped thin film evaporator, a short-path evaporator, a forced circulation evaporator, a spiral tube evaporator, and a flash cooling evaporator, etc.

[0036] The hydration vessel 4 is equipped with a temperature sensor and a pH sensor.

[0037] After a 2-acrylamido-2-methylpropanesulfonate solution with low acrylonitrile content enters the temporary storage vessel, key indicators such as the concentration of 2-acrylamido-2-methylpropanesulfonate and the content of polymerization inhibitor need to be tested. Based on the test results, deionized water and polymerization inhibitor can be added to precisely adjust the aforementioned indicators to the range specified by the manufacturer for product delivery.

[0038] Example 2 The method for preparing an ultra-low acrylonitrile content 2-acrylamido-2-methylpropanesulfonate solution using the system described in Example 1 includes the following steps: (1) Undried crude 2-acrylamido-2-methylpropanesulfonic acid (acrylonitrile mass fraction of 15%) was continuously fed into neutralization vessel 1 at a rate of 500 kg / h. At the same time, a sodium hydroxide solution with a mass fraction of 20% was fed into neutralization vessel 1 at a rate of 420 kg / h. The polymerization inhibitor p-hydroxyanisole was added into the neutralization vessel at the same time as the sodium hydroxide solution at a rate of 40 g / h. The temperature of neutralization vessel 1 was controlled at 25℃. The mass fraction of the first 2-acrylamido-2-methylpropanesulfonic acid that overflowed was 55.64%; the mass fraction of acrylonitrile was 8.9%.

[0039] (2) The first aqueous solution of sodium 2-acrylamido-2-methylpropanesulfonate is introduced into the oil-water separator 2 and separated into two phases by density difference: an acrylonitrile phase and a second aqueous solution of sodium 2-acrylamido-2-methylpropanesulfonate. The acrylonitrile overflow rate is approximately 75 kg / h. The mass fraction of acrylonitrile in the second aqueous solution of sodium 2-acrylamido-2-methylpropanesulfonate is 2.5%.

[0040] (3) The second aqueous solution of sodium 2-acrylamido-2-methylpropanesulfonate was introduced into the thin film evaporator at a rate of 845 kg / h. The temperature of the evaporator was 30°C and the vacuum degree was 50 mbar. After distillation, the solution was cooled to room temperature to obtain the third aqueous solution of sodium 2-acrylamido-2-methylpropanesulfonate. The concentration of acrylonitrile in the third aqueous solution of sodium 2-acrylamido-2-methylpropanesulfonate was 350 ppm.

[0041] (4) The aqueous solution of sodium 2-acrylamido-2-methylpropanesulfonate (3) was transferred to the hydration reactor 4, and the temperature was controlled at 15~25℃. The reaction in the hydration reactor was a batch reaction. When the amount of solution entering reached 10 t, 50 kg of aqueous solution containing 25 g of bio-enzyme purified from fermentation broth (fermentation broth purchased from Dongying Baomo Environmental Engineering Co., Ltd.) was added, and the reaction was stirred. The acrylonitrile content was monitored by chromatography. When the acrylonitrile content was <1 ppm, the aqueous solution of sodium 2-acrylamido-2-methylpropanesulfonate (4) was obtained in about 3 h.

[0042] (5) The fourth aqueous solution of sodium 2-acrylamido-2-methylpropanesulfonate was pumped into an ultrafiltration membrane filtration device. The pore size of the ultrafiltration membrane was 0.01 μm. After ultrafiltration, the aqueous solution of sodium 2-acrylamido-2-methylpropanesulfonate was transferred to a temporary storage vessel. 1128 kg of deionized water and 90 kg of the polymerization inhibitor p-hydroxyanisole were added to prepare an aqueous solution of sodium 2-acrylamido-2-methylpropanesulfonate with an ultra-low acrylonitrile content of 50% and a polymerization inhibitor content of 90 ppm. The solution color was <20. Chromatographic analysis (e.g.) was performed to determine the color of the solution. Figure 1 As shown in the figure, the acrylonitrile (peak 4) content in the final product is 1 ppm.

[0043] The sodium 2-acrylamido-2-methylpropanesulfonate aqueous solution with ultra-low acrylonitrile content obtained in this embodiment was used to prepare a polyacrylamide product for oil displacement (the amount added accounts for about 30% of the total mass of monomers). The molecular weight can reach 30 million, the water insoluble content is 0.02%, and the apparent viscosity reaches 18.5 mPa.s.

[0044] Comparative Example 1 The first aqueous solution of sodium 2-acrylamido-2-methylpropanesulfonate in Example 2 was diluted to a 50% (w / w) aqueous solution of sodium 2-acrylamido-2-methylpropanesulfonate, with the same amount of polymerization inhibitor added (90 ppm), and used as a control raw material solution. The test results showed that the residual acrylonitrile in this control raw material solution was approximately 200 ppm, and the color was approximately 40. An oil displacement polyacrylamide product was prepared using the exact same formulation as in Example 2. The resulting product had a molecular weight of approximately 27 million, a water-insoluble content of 0.18%, and an apparent viscosity of 16.8 mPa·s.

[0045] A comparison of the two groups of samples shows that reducing the residual acrylonitrile in the raw materials significantly increases the molecular weight and apparent viscosity of the synthesized polymer, while greatly reducing the content of water-insoluble matter. This improvement is an order of magnitude.

[0046] Example 3 The sodium 2-acrylamido-2-methylpropanesulfonate aqueous solution with ultra-low acrylonitrile content prepared in Example 2 was used to prepare a temperature-resistant and salt-resistant oil displacement polymer (the sodium 2-acrylamido-2-methylpropanesulfonate content accounts for 60% of the total mass of the monomer, the water-insoluble matter is ≤0.1%, and the filtration ratio is ≤1.2). The molecular weight can reach 25 million, the water-insoluble matter content is 0.02%, and the filtration ratio is 1.01.

[0047] Comparative Example 2 The control raw material solution in Comparative Example 1 was used to prepare the same product as in Example 3. The resulting polymer had a molecular weight of approximately 22 million, a water-insoluble content of 0.2%, and a filtration ratio of 1.3, which did not meet the requirements for use at all.

[0048] Comparison of the performance of the two groups of samples shows that the raw material treated with acrylonitrile removal has a more significant advantage under high addition conditions compared to the system without acrylonitrile removal. This is because the higher the amount of raw material added, the greater the total amount of acrylonitrile impurities introduced into the system, and the amplified negative impact on the various properties of the downstream finished product will also be.

[0049] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a 2-acrylamido-2-methylpropanesulfonate solution with ultra-low acrylonitrile content, characterized in that, Includes the following steps: The undried crude 2-acrylamido-2-methylpropanesulfonic acid was neutralized with an alkaline solution to obtain an aqueous solution of the first 2-acrylamido-2-methylpropanesulfonate; the mass fraction of acrylonitrile in the first 2-acrylamido-2-methylpropanesulfonate aqueous solution was 5-30%. The first 2-acrylamido-2-methylpropanesulfonate aqueous solution was separated into two phases by density difference, namely an acrylonitrile phase and a second 2-acrylamido-2-methylpropanesulfonate aqueous solution phase; The aqueous solution of the second 2-acrylamido-2-methylpropanesulfonate was distilled to obtain the aqueous solution of the third 2-acrylamido-2-methylpropanesulfonate. A catalyst for the hydration reaction of acrylonitrile was added to the aqueous solution of the third 2-acrylamido-2-methylpropanesulfonate, and the reaction temperature and time were controlled to obtain the aqueous solution of the fourth 2-acrylamido-2-methylpropanesulfonate. The catalyst for the acrylonitrile hydration reaction was separated by filtration of the aqueous solution of the fourth 2-acrylamido-2-methylpropanesulfonate to obtain a 2-acrylamido-2-methylpropanesulfonate solution with ultra-low acrylonitrile content, the acrylonitrile content of which was less than 1 ppm.

2. The preparation method as described in claim 1, characterized in that, The mass ratio of acrylonitrile to 2-acrylamido-2-methylpropanesulfonic acid in the undried crude 2-acrylamido-2-methylpropanesulfonic acid is (5:95) to (30:70).

3. The preparation method as described in claim 1, characterized in that, The alkali includes one of alkali metal or alkaline earth metal hydroxide, alkali metal or alkaline earth metal oxide and ammonia. Alternatively, the mass fraction of the alkali solution is 10-50%, preferably 15-30%.

4. The preparation method as described in claim 3, characterized in that, When the alkali is an alkali metal or alkaline earth metal oxide, it may be selected from sodium hydroxide, potassium hydroxide, lithium hydroxide, magnesium hydroxide, and calcium hydroxide. Alternatively, the alkali may be an alkali metal or alkaline earth metal oxide, selected from sodium oxide, potassium oxide, calcium oxide, and magnesium oxide.

5. The preparation method as described in claim 1, characterized in that, The mass fraction of 2-acrylamido-2-methylpropanesulfonate in the first aqueous solution of 2-acrylamido-2-methylpropanesulfonate is 50-65%; Alternatively, during the neutralization reaction, the temperature is controlled at 10~30℃ and the pH value is controlled at 8.5~10.

0.

6. The preparation method as described in claim 1, characterized in that, During the neutralization reaction, polymerization inhibitors can be added; Preferably, the polymerization inhibitor comprises one or more of thiazide, 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxy, phenylenediamine derivatives and mixtures thereof, or phenolic derivatives; Preferably, the mass fraction of the polymerization inhibitor is 10~50 ppm.

7. The preparation method as described in claim 1, characterized in that, The distillation method is vacuum distillation, with a vacuum level of 30~150 mbar and a temperature of 25~35℃.

8. The preparation method as described in claim 1, characterized in that, The catalyst for the acrylonitrile hydration reaction is a bio-enzyme catalyst; Preferably, the amount of bio-enzyme catalyst added is 0.5~4 kg / ton of acrylonitrile; Alternatively, the hydration reaction temperature is 15~25℃, the hydration reaction time is 1~4 h, and the pH during the hydration reaction is 8.5~9.

5.

9. The preparation method as described in claim 1, characterized in that, An ultrafiltration membrane with a pore size of 0.005~0.05 μm is used for filtration.

10. A system for producing a 2-acrylamido-2-methylpropanesulfonate solution with ultra-low acrylonitrile content as described in any one of claims 1 to 9, characterized in that, It includes a neutralization vessel, an oil-water separator, a distillation unit, a hydration vessel, and a temporary storage vessel connected in sequence. The neutralization vessel is used to neutralize undried crude 2-acrylamido-2-methylpropanesulfonic acid with alkaline solution. An oil-water separator is used to separate a first aqueous solution of 2-acrylamido-2-methylpropanesulfonate into two phases by means of density difference; The distillation apparatus was used for distilling the second 2-acrylamido-2-methylpropanesulfonate aqueous solution; The hydration reactor is used to carry out a hydration reaction of the aqueous solution of 2-acrylamido-2-methylpropanesulfonate to convert acrylonitrile into acrylamide. The temporary storage vessel is used to store a 2-acrylamido-2-methylpropanesulfonate solution with ultra-low acrylonitrile content obtained after filtering and separating the catalyst for the acrylonitrile hydration reaction.

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