Method for purifying AMPS

Abstract

The invention provides a purification method of AMPS, and belongs to the technical field of sulfonic acid. The purification method comprises the steps of dissolving and filtering, ion exchange purification and crystallization. The dissolving and filtering method comprises the following steps: adding the AMPS crude product into methanol, stirring and dissolving at 30-50 DEG C, then adding trisodium citrate, uniformly stirring, standing for 20-30 minutes, and filtering through a 0.2-0.5 mu m microporous filter membrane to obtain filtrate; the purity of the purified AMPS ranges from 99.58% to 99.64%, the mass content of Fe < 3 + > is smaller than or equal to 0.0003%, the yield ranges from 86.21% to 86.35%, and the yield ranges from 92.46% to 92.51%.

Description

Technical Field

[0001] The invention belongs to the technical field of sulfonic acid, and particularly relates to a method for purifying AMPS. Background Art

[0002] 2-Acrylamido-2-methylpropanesulfonic acid (AMPS) is an important functional monomer widely used in water treatment, oilfield chemistry, polymer materials and other fields. During the preparation of AMPS, whether through mainstream processes such as sulfonation or other synthesis methods, the resulting crude AMPS often contains unreacted raw materials, impurities produced by side reactions, catalyst residues, polymerization inhibitors, etc. The presence of these impurities can affect the performance and application effects of AMPS. For example, in polymerization reactions, impurities may lead to unstable polymerization reaction rates, a wider polymer molecular weight distribution, and reduced product quality.

[0003] Currently, common AMPS purification methods include recrystallization and ion exchange. While recrystallization is relatively simple to operate, its effectiveness in removing certain impurities is limited, and repeated recrystallizations can lead to reduced product yields. Ion exchange can effectively remove ionic impurities, but the equipment is expensive and requires regular regeneration and maintenance of the ion exchange resin, increasing production costs and operational complexity. Therefore, there is an urgent need to develop an AMPS purification method that is simple to operate, has good purification effects, and is low-cost. Summary of the Invention

[0004] In response to the problems existing in the prior art, the present invention provides a method for purifying AMPS to achieve the following invention objectives: it can effectively remove various impurities in the crude AMPS product, significantly improve the product purity, and at the same time ensure a high product yield, reduce production costs, and meet the needs of industrial production.

[0005] In order to solve the above technical problems, the technical solutions adopted by the present invention are as follows: A method for purifying AMPS, comprising: 1. Dissolution and filtration Add the crude AMPS to methanol, stir and dissolve at 30-50°C, then add trisodium citrate, stir evenly, let stand for 20-30 minutes, and filter through a 0.2-0.5 μm microporous filter membrane to obtain a filtrate; The purity of the AMPS crude product is 90-95%, of which Fe 3+ The mass content is 0.004~0.008%; The mass ratio of the crude AMPS, methanol, and trisodium citrate is 0.8-1.2:4.5-5.5:0.005-0.007; The stirring rate is 25-35 r / min.

[0006] 2. Ion exchange purification Soak the anion exchange resin in saturated salt water for 18 to 22 hours, wash with deionized water until the supernatant is colorless and odorless, then soak it in NaOH solution for 3 to 5 hours, wash it with deionized water until it is neutral, and then soak it in Na2SO4 solution for 1 to 3 hours. Then, slowly transfer the resin to the chromatography column and slowly load the filtrate from the top of the column at a flow rate of 2 to 4 BV / h. After loading, first elute with a methanol solution of 15 to 25% by mass to remove weakly adsorbed impurities, then elute with a methanol solution of 75 to 85% by mass, collect the liquid below the column to obtain AMPS solution; The concentration of the NaOH solution is 0.8-1.2 mol / L; The concentration of the Na2SO4 solution is 0.45-0.55 mol / L; The preparation method of the anion exchange resin comprises the following steps: mixing styrene, divinylbenzene and benzoyl peroxide, stirring until uniform, slowly adding the mixture dropwise to a polyvinyl alcohol solution at 60-70° C., heating the mixture to 80-90° C., reacting the mixture for 4-6 hours, cooling the mixture at room temperature, filtering the mixture, and washing the mixture with hot water to obtain a white ball resin; immersing the white ball resin in dichloroethane and swelling the mixture at room temperature for 4-6 hours; adding anhydrous zinc chloride, stirring the mixture at 40-50° C. for reaction for 8-12 hours, filtering the mixture, and washing the mixture with methanol and deionized water until the mixture is neutral to obtain a chloromethylated resin; adding the chloromethylated resin to a trimethylamine solution, stirring the mixture at room temperature for reaction for 10-12 hours, filtering the mixture, and washing the mixture with deionized water until the mixture is neutral to obtain an anion exchange resin; In the preparation method of the anion exchange resin, the mass ratio of styrene, divinylbenzene, benzoyl peroxide, and polyvinyl alcohol solution is 8.8-9.2:0.9-1.1:0.08-0.12:20-30; The mass fraction of the polyvinyl alcohol solution is 0.4-0.6%; The mass ratio of the white ball resin, dichloroethane and anhydrous zinc chloride is 0.8-1.2:6-8:0.7-0.9; The mass ratio of the chloromethylated resin to the trimethylamine solution is 0.8-1.2:9-11; The mass fraction of the trimethylamine solution is 30-40%.

[0007] 3. Crystallization Acetone is added to the AMPS solution, and after cooling and crystallization at 0-5°C for 1-3 hours, the crystals are vacuum dried at 40-60°C to a constant weight to obtain purified AMPS; The mass ratio of the AMPS solution to acetone is 4-6:1.8-2.2.

[0008] Compared with the prior art, the present invention has the following beneficial effects: Adding trisodium citrate in step 1 can effectively complex the metal ions in the solution and then remove them by filtration; In step 2, the anion exchange resin can effectively and accurately adsorb AMPS by utilizing the electrostatic interaction between the sulfonic acid group (-SO3H) of AMPS and the quaternary ammonium group (-N(CH3)3) on the resin, and obtain a high-purity AMPS solution through elution; In step 3, acetone is added during the crystallization process. Acetone is miscible with methanol in the AMPS solution, but is almost insoluble in AMPS. Adding acetone to the AMPS solution allows AMPS to crystallize rapidly, thereby separating impurities and avoiding multiple crystallizations to obtain purified AMPS. The purity of the purified AMPS is 99.58-99.64%, of which Fe 3+ The mass content is ≤0.0003%, the yield is 86.21~86.35%, and the productivity is 92.46~92.51%. DETAILED DESCRIPTION

[0009] Example 1 A method for purifying AMPS, comprising: 1. Dissolution and filtration The crude AMPS was added to methanol and dissolved by stirring at 40°C. Then, trisodium citrate was added and stirred evenly. After standing for 25 minutes, the mixture was filtered through a 0.3 μm microporous filter membrane to obtain a filtrate. The purity of the AMPS crude product is 95%, of which Fe 3+ The mass content is 0.006%; The mass ratio of the crude AMPS, methanol, and trisodium citrate is 1:5:0.006; The stirring rate is 30 r / min.

[0010] 2. Ion exchange purification Soak the anion exchange resin in saturated brine for 20 hours, wash with deionized water until the supernatant is colorless and odorless, then soak it in NaOH solution for 4 hours, wash with deionized water until neutral, and then soak it in Na2SO4 solution for 2 hours. Then, slowly transfer the resin to the chromatography column, and slowly load the filtrate from the top of the column at a controlled flow rate of 3BV / h. After loading, first elute with 20% methanol solution to remove weakly adsorbed impurities, then elute with 80% methanol solution, collect the liquid below the column to obtain AMPS solution; The concentration of the NaOH solution is 1 mol / L; The concentration of the Na2SO4 solution is 0.5 mol / L; The anion exchange resin is prepared by mixing styrene, divinylbenzene, and benzoyl peroxide, stirring until uniform, slowly adding the mixture dropwise to a polyvinyl alcohol solution at 65° C., heating the mixture to 85° C., reacting for 5 hours, cooling the mixture at room temperature, filtering the mixture, and washing the mixture with hot water to obtain a white ball resin. The white ball resin is immersed in dichloroethane and swelled at room temperature for 5 hours. Anhydrous zinc chloride is then added, stirring the mixture at 45° C. for 10 hours, filtering the mixture, and washing the mixture with methanol and deionized water until the mixture is neutral to obtain a chloromethylated resin. The chloromethylated resin is added to a trimethylamine solution, stirring the mixture at room temperature for 11 hours, filtering the mixture, and washing the mixture with deionized water until the mixture is neutral to obtain an anion exchange resin. In the preparation method of the anion exchange resin, the mass ratio of styrene, divinylbenzene, benzoyl peroxide, and polyvinyl alcohol solution is 9:1:0.1:25; The mass fraction of the polyvinyl alcohol solution is 0.5%; The mass ratio of the white ball resin, dichloroethane and anhydrous zinc chloride is 1:7:0.8; The mass ratio of the chloromethylated resin to the trimethylamine solution is 1:10; The mass fraction of the trimethylamine solution is 35%.

[0011] 3. Crystallization Acetone was added to the AMPS solution, and after cooling and crystallization at 3°C ​​for 2 h, the crystals were vacuum dried at 50°C to constant weight to obtain purified AMPS; The mass ratio of the AMPS solution to acetone is 5:2.

[0012] Example 2 A method for purifying AMPS, comprising: 1. Dissolution and filtration The crude AMPS was added to methanol and stirred at 30°C to dissolve, and then trisodium citrate was added. After stirring evenly, the mixture was allowed to stand for 20 minutes and then filtered through a 0.2 μm microporous membrane to obtain a filtrate. The purity of the AMPS crude product is 95%, of which Fe 3+ The mass content is 0.006%; The mass ratio of the crude AMPS, methanol, and trisodium citrate is 0.8:4.5:0.005; The stirring rate is 25 r / min.

[0013] 2. Ion exchange purification Soak the anion exchange resin in saturated brine for 18 hours, wash with deionized water until the supernatant is colorless and odorless, then soak it in NaOH solution for 3 hours, wash with deionized water until neutral, and then soak it in Na2SO4 solution for 1 hour. Slowly transfer the resin to the chromatography column, and slowly load the filtrate from the top of the column at a controlled flow rate of 2BV / h. After loading, first elute with 15% methanol solution to remove weakly adsorbed impurities, then elute with 75% methanol solution, collect the liquid below the column to obtain AMPS solution; The concentration of the NaOH solution is 0.8 mol / L; The concentration of the Na2SO4 solution is 0.45 mol / L; The anion exchange resin is prepared by mixing styrene, divinylbenzene, and benzoyl peroxide, stirring until uniform, slowly adding the mixture dropwise to a polyvinyl alcohol solution at 60° C., heating the mixture to 80° C., reacting for 4 hours, cooling the mixture at room temperature, filtering the mixture, and washing the mixture with hot water to obtain a white ball resin. The white ball resin is immersed in dichloroethane and swelled at room temperature for 4 hours. Anhydrous zinc chloride is then added, stirring the mixture at 40° C. for 8 hours, filtering the mixture, and washing the mixture with methanol and deionized water until the mixture is neutral to obtain a chloromethylated resin. The chloromethylated resin is added to a trimethylamine solution, stirring the mixture at room temperature for 10 hours, filtering the mixture, and washing the mixture with deionized water until the mixture is neutral to obtain an anion exchange resin. In the preparation method of the anion exchange resin, the mass ratio of styrene, divinylbenzene, benzoyl peroxide, and polyvinyl alcohol solution is 8.8:0.9:0.08:20; The mass fraction of the polyvinyl alcohol solution is 0.4%; The mass ratio of the white ball resin, dichloroethane and anhydrous zinc chloride is 0.8:6:0.7; The mass ratio of the chloromethylated resin to the trimethylamine solution is 0.8:9; The mass fraction of the trimethylamine solution is 30%.

[0014] 3. Crystallization Acetone was added to the AMPS solution, and after cooling and crystallization at 0°C for 1 hour, the crystals were vacuum dried at 40°C to constant weight to obtain purified AMPS; The mass ratio of the AMPS solution to acetone is 4:1.8.

[0015] Example 3 A method for purifying AMPS, comprising: 1. Dissolution and filtration The crude AMPS was added to methanol and stirred at 50°C to dissolve. Then, trisodium citrate was added and stirred evenly. After standing for 30 minutes, the mixture was filtered through a 0.5 μm microporous filter membrane to obtain a filtrate. The purity of the AMPS crude product is 95%, of which Fe 3+ The mass content is 0.006%; The mass ratio of the crude AMPS, methanol, and trisodium citrate is 1.2:5.5:0.007; The stirring rate is 35 r / min.

[0016] 2. Ion exchange purification Soak the anion exchange resin in saturated brine for 22 hours, wash with deionized water until the supernatant is colorless and odorless, then soak it in NaOH solution for 5 hours, wash it with deionized water until it is neutral, and then soak it in Na2SO4 solution for 3 hours. Then, slowly transfer the resin to the chromatography column, and slowly load the filtrate from the top of the column at a controlled flow rate of 4 BV / h. After loading, first elute with 25% methanol solution to remove weakly adsorbed impurities, then elute with 85% methanol solution, collect the liquid below the column to obtain AMPS solution; The concentration of the NaOH solution is 1.2 mol / L; The concentration of the Na2SO4 solution is 0.55 mol / L; The anion exchange resin is prepared by mixing styrene, divinylbenzene, and benzoyl peroxide, stirring until uniform, slowly adding the mixture dropwise to a polyvinyl alcohol solution at 70° C., heating the mixture to 90° C., reacting for 6 hours, cooling the mixture at room temperature, filtering the mixture, and washing the mixture with hot water to obtain a white ball resin. The white ball resin is immersed in dichloroethane and swelled at room temperature for 6 hours. Anhydrous zinc chloride is then added, stirring the mixture at 50° C. for 12 hours, filtering the mixture, and washing the mixture with methanol and deionized water until the mixture is neutral to obtain a chloromethylated resin. The chloromethylated resin is added to a trimethylamine solution, stirring the mixture at room temperature for 12 hours, filtering the mixture, and washing the mixture with deionized water until the mixture is neutral to obtain an anion exchange resin. In the preparation method of the anion exchange resin, the mass ratio of styrene, divinylbenzene, benzoyl peroxide, and polyvinyl alcohol solution is 9.2:1.1:0.12:30; The mass fraction of the polyvinyl alcohol solution is 0.6%; The mass ratio of the white ball resin, dichloroethane and anhydrous zinc chloride is 1.2:8:0.9; The mass ratio of the chloromethylated resin to the trimethylamine solution is 1.2:11; The mass fraction of the trimethylamine solution is 40%.

[0017] 3. Crystallization Acetone was added to the AMPS solution, and after cooling and crystallization at 5°C for 3 h, the crystals were vacuum dried at 60°C to constant weight to obtain purified AMPS; The mass ratio of the AMPS solution to acetone is 6:2.2.

[0018] Example 4 A method for purifying AMPS is provided, based on Example 1, except that step 2 is deleted and the remaining steps are the same.

[0019] Example 5 A method for purifying AMPS is provided. Based on Example 1, the addition of trisodium citrate is omitted in step 1, and the remaining steps are the same.

[0020] Test example 1. The purity and Fe content of AMPS prepared in Examples 1 to 5 were measured respectively. 3+ The mass content, yield and productivity of the product were tested, and the test results are shown in Table 1: Yield = mass of purified AMPS / mass of crude AMPS × 100% Yield = actual output / theoretical output × 100% Table 1

[0021] From the above results, it can be seen that although the yield and productivity of Example 4 are slightly higher than those of Example 1, Example 4 lacks an anion exchange membrane, which makes it impossible to effectively remove ionic impurities, thereby reducing the purity. If the purity needs to be improved, multiple crystallizations are required, which will lead to a decrease in yield and productivity. Example 5 Omitting the addition of trisodium citrate in step 1 results in an inability to effectively remove metal ions from the crude product. 3+ The mass content is greater than 0.0003%.

Claims

1. A method for purifying AMPS, characterized in that: The purification method includes dissolution and filtration, ion exchange purification, and crystallization; The dissolution and filtration method comprises adding the crude AMPS product to methanol, stirring and dissolving it at 30-50° C., then adding trisodium citrate, stirring evenly, standing for 20-30 minutes, and filtering through a 0.2-0.5 μm microporous filter membrane to obtain a filtrate; The ion exchange purification method comprises soaking an anion exchange resin in saturated saline for 18 to 22 hours, washing with deionized water until the supernatant is colorless and odorless, then soaking in a NaOH solution for 3 to 5 hours, washing with deionized water until neutral, and then soaking in a Na2SO4 solution for 1 to 3 hours, slowly transferring the resin to a chromatography column, slowly loading the filtrate from the top of the column, controlling the flow rate to 2 to 4 BV / h, and after the loading is completed, first eluting with a methanol solution with a mass fraction of 15 to 25% to remove weakly adsorbed impurities, and then eluting with a methanol solution with a mass fraction of 75 to 85%, collecting the liquid below the column to obtain an AMPS solution.

2. The method for purifying AMPS according to claim 1, wherein: In the dissolution and filtration method, the purity of the AMPS crude product is 90-95%, of which Fe 3+ The mass content of AMPS is 0.004-0.008%, the mass ratio of crude AMPS, methanol and trisodium citrate is 0.8-1.2:4.5-5.5:0.005-0.007; the stirring speed is 25-35r / min.

3. The method for purifying AMPS according to claim 1, wherein: In the ion exchange purification method, the concentration of the NaOH solution is 0.8-1.2 mol / L; the concentration of the Na2SO4 solution is 0.45-0.55 mol / L.

4. The method for purifying AMPS according to claim 1, wherein: In the ion exchange purification method, the anion exchange resin is prepared by mixing styrene, divinylbenzene and benzoyl peroxide, stirring until uniform, slowly adding the mixture dropwise to a polyvinyl alcohol solution at 60-70°C, then heating to 80-90°C, reacting for 4-6 hours, cooling at room temperature, filtering, and washing with hot water to obtain a white ball resin, soaking the white ball resin in dichloroethane, swelling it at room temperature for 4-6 hours, then adding anhydrous zinc chloride, stirring and reacting it at 40-50°C for 8-12 hours, filtering, washing the resin with methanol and deionized water until neutral, obtaining a chloromethylated resin, adding the chloromethylated resin to a trimethylamine solution, stirring and reacting it at room temperature for 10-12 hours, filtering, and washing it with deionized water until neutral, thereby obtaining an anion exchange resin.

5. The method for purifying AMPS according to claim 4, wherein: In the preparation method of the anion exchange resin, the mass ratio of styrene, divinylbenzene, benzoyl peroxide, and polyvinyl alcohol solution is 8.8-9.2:0.9-1.1:0.08-0.12:20-30; the mass fraction of the polyvinyl alcohol solution is 0.4-0.6%; the mass ratio of white ball resin, ethylene dichloride, and anhydrous zinc chloride is 0.8-1.2:6-8:0.7-0.9; the mass ratio of chloromethylated resin and trimethylamine solution is 0.8-1.2:9-11; and the mass fraction of the trimethylamine solution is 30-40%.

6. The method for purifying AMPS according to claim 1, wherein: The crystallization method comprises the following steps: adding acetone to an AMPS solution, cooling and crystallizing at 0-5° C. for 1-3 hours, and then vacuum drying the crystals at 40-60° C. to a constant weight to obtain purified AMPS.

7. The method for purifying AMPS according to claim 6, wherein: In the crystallization method, the mass ratio of the AMPS solution to acetone is 4-6:1.8-2.2.

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