A method for recovering 2-acrylamido-2-methylpropanesulfonic acid

Abstract

The present invention belongs to the technical field of purification and recovery of 2-acrylamide-2-methylpropane sulfonic acid, specifically discloses a recovery method of 2-acrylamide-2-methylpropane sulfonic acid, comprising the following steps: S1, adding the recrystallization filtrate to the first container for vacuum distillation, adding a certain weight of stabilizer, distillation temperature 50-80 DEG C, distilling until the material begins to be turbid, and the distillation concentrate is standby; S2, adding an organic solvent in advance into the second container, the weight ratio of the addition amount of the organic solvent to the distillation concentrate is 0.5-3:1; S3, the distillation concentrate is slowly transferred into the second container, crystallization 20-40min, and then cooled to 10-20 DEG C; solid-liquid separation and drying are carried out afterwards to obtain 2-acrylamide-2-methylpropane sulfonic acid products. The product obtained by this method has high purity, good stability and low solvent residue, which effectively solves the technical problems such as the easy stickiness of traditional method materials, low product purity and low yield.

Description

Technical Field

[0001] The invention relates to the technical field of production of 2-acrylamide-2-methylpropane sulfonic acid, and in particular to a method for recovering 2-acrylamide-2-methylpropane sulfonic acid. Background Art

[0002] 2-Acrylamido-2-methylpropanesulfonic acid (AMPS for short) is a multifunctional water-soluble anionic monomer that is very easy to self-polymerize or copolymerize with other olefin monomers. Because the AMPS structure contains a sulfonic acid group that is strongly anionic, water-soluble, and insensitive to salt, a shielded amide group, and an unsaturated double bond, it has excellent properties. The special structure of AMPS can also be used to improve the comprehensive properties of non-water-soluble polymers. Its polymers are all excellent functional polymer electrolytes. As dye fixatives, flocculants, dispersants, and thickeners, they have been widely used in chemical fibers, plastics, coatings, surfactants, papermaking, water treatment, and oilfield chemistry.

[0003] At present, the production of 2-acrylamide-2-methylpropane sulfonic acid mostly adopts the batch method, with acrylonitrile and fuming sulfuric acid as the main raw materials to react to generate a slurry product, which is separated and dried to obtain a crude 2-acrylamide-2-methylpropane sulfonic acid, and then the crude 2-acrylamide-2-methylpropane sulfonic acid is dissolved in acetic acid and an aqueous solution system by a recrystallization process, and then centrifuged and other steps are used to perform recrystallization and purification, and finally a high-purity 2-acrylamide-2-methylpropane sulfonic acid product is obtained. The raw materials of this process route are easily available, the reaction conditions are mild, and the yield and quality of the product are relatively stable, so this route is adopted by many manufacturers. Due to the limitation of the recrystallization process and the solubility of the 2-acrylamide-2-methylpropane sulfonic acid product, in the recrystallization filtrate after centrifugation in the recrystallization process, except that a considerable amount of 2-acrylamide-2-methylpropane sulfonic acid is not separated out completely, there are also many foreign substances with large contents dissolved in the recrystallization filtrate, such as acetic acid, acrylonitrile and some other byproducts of reaction, and the recrystallization filtrate has been subjected to long-term and frequent temperature rise and fall operations, and a large part of the residual product inside has undergone phenomena such as polymerization and deterioration, and the material is easily sticky. If conventional distillation extraction method is simply adopted, the 2-acrylamide-2-methylpropane sulfonic acid in the recrystallization filtrate cannot be extracted to carry out operations such as drying, and even if the 2-acrylamide-2-methylpropane sulfonic acid in the recrystallization filtrate is extracted, the quality level of the products obtained therefrom is poor due to the existence of other components. Therefore, there has been no effective method for extracting 2-acrylamide-2-methylpropane sulfonic acid from the recrystallization filtrate, resulting in the 2-acrylamide-2-methylpropane sulfonic acid remaining in the recrystallization filtrate being wasted, increasing the difficulty of recovery, being detrimental to the environmental protection requirements of production, and also causing unnecessary losses of products.

[0004] In order to solve the above problems, the inventor of this case has proposed a method for extracting 2-acrylamido-2-methylpropanesulfonic acid from the recrystallization filtrate (CN103086930A). This method adopts a vacuum distillation method, by adding a stabilizer and then controlling the distillation temperature for recovery and extraction. However, the system after distillation in this method still contains a large concentration of water. The presence of a large concentration of water (especially at relatively high temperatures) will lead to the following problems: First, it is easy to cause the material to polymerize and become sticky, which not only affects the purity and stability of the product, but also brings difficulties to the actual production discharge, centrifugation and other operations; second, due to the high solubility of AMPS material in water, a considerable part of the product will still be dissolved in it and cannot be precipitated, resulting in a low recovery rate of the product. Therefore, the overall technology has a low product recovery rate, low purity, and uncontrolled quality level; third, the solvent residue of the precipitated material is high. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a method for recovering 2-acrylamide-2-methylpropane sulfonic acid. The product obtained by the method has higher purity, lower solvent residue, better product stability, and the material is not easy to polymerize and become sticky during the recovery process.

[0006] In order to solve the above technical problems, the technical solution of the present invention is:

[0007] A method for recovering 2-acrylamido-2-methylpropanesulfonic acid comprises the following steps:

[0008] S1, adding the recrystallized filtrate of 2-acrylamide-2-methylpropane sulfonic acid into the first container for vacuum distillation, and adding 0.001% to 0.006% of the stabilizer relative to the weight of the recrystallized filtrate, the distillation temperature is 50 to 80° C., the vacuum degree is ≥ 0.08Mpa, and the material is distilled until it begins to become turbid, then the heating is stopped, the vacuum system is turned off, and the distilled concentrate in the first container is set aside;

[0009] S2, adding an organic solvent into the second container in advance, wherein the weight ratio of the organic solvent added to the distilled concentrate in the first container is 0.5 to 3:1;

[0010] S3, slowly transferring the distillation concentrate in the first container into a second container with an organic solvent, allowing the distillation concentrate to cool naturally during the transfer process. After all the distillation concentrate in the first container is transferred into the second container, growing the crystals for 20 to 40 minutes, and then cooling to 10 to 20° C.; then performing solid-liquid separation and drying to obtain a 2-acrylamido-2-methylpropanesulfonic acid product.

[0011] Wherein, in step S1, the stabilizer is p-hydroxyanisole or hydroquinone, preferably p-hydroxyanisole.

[0012] Preferably, in step S1, the distillation temperature is 60-70°C.

[0013] Preferably, in step S1, the distillation heating method adopts hot water bath heating, and the hot water bath temperature is 80-90°C.

[0014] In step S2, the organic solvent may be acetic acid, acetone, acetonitrile or ethyl acetate, preferably acetic acid.

[0015] Preferably, in step S3, the transfer time of the distillation concentrate in the first container to the second container is preferably controlled within 20 to 30 minutes.

[0016] Preferably, the first container is a distillation kettle, and the second container is a crystallization kettle.

[0017] Compared with the prior art, the present invention has at least the following beneficial effects: after the filtrate of recrystallization of 2-acrylamide-2-methylpropanesulfonic acid is concentrated to a certain degree by vacuum distillation, an organic solvent is used for reverse crystallization, that is, the distillation concentrate is slowly transferred into the organic solvent, so that firstly, the proportion of water in the system is greatly reduced, the material is less likely to polymerize and become sticky, and the yield will be higher, and the resource utilization rate is high; secondly, the material concentration of the initial crystallization is dispersed, the crystallized material is not easy to wrap the solvent, and the solvent residue is low; thirdly, the organic solvent has a certain solubility for impurities, which is equivalent to a purification of the recovered product, and the obtained product has higher purity; fourthly, after the extraction rate is high, the subsequent distillation kettle residue of the secondary filtrate is lower, the processing difficulty is reduced, and it is more economical and environmentally friendly.

[0018] The invention can scientifically and reasonably recover the 2-acrylamide-2-methylpropane sulfonic acid product in the recrystallization filtrate, and the obtained product has high purity, good stability, low solvent residue, simple operation, and is easy to industrialize. The invention effectively solves the technical problems of easy stickiness of materials, low product purity, low yield, etc. when extracting 2-acrylamide-2-methylpropane sulfonic acid from the recrystallization filtrate, and has great economic value and social value. DETAILED DESCRIPTION

[0019] The present invention will be further described below in conjunction with the embodiments. In the following detailed description, only certain exemplary embodiments of the present invention are described by way of illustration. Needless to say, those of ordinary skill in the art will appreciate that the described embodiments may be modified in a variety of ways without departing from the spirit and scope of the present invention. Therefore, the following description is illustrative in nature and is not intended to limit the scope of protection of the claims.

[0020] Example 1

[0021] 5000 kg of 2-acrylamide-2-methylpropanesulfonic acid recrystallization filtrate was added to the distillation kettle, heated in a hot water bath with hot water at 80°C, stirred, added 0.3 kg of p-hydroxyanisole, the distillation temperature in the distillation kettle was 65°C, vacuum distillation was performed, the vacuum degree was ≥ 0.08 MPa, the distillation produced liquid was condensed and stored in a temporary storage tank, and when the material in the kettle became turbid, the hot water heating was turned off and the vacuum was turned off. Within 20 minutes, the above materials were slowly transferred to the crystallization kettle, 0.5 times of acetic acid was added to the kettle in advance, and the temperature was naturally lowered. After the transfer was completed, the stirring frequency was adjusted to 20HZ, and the temperature was lowered to 15°C for centrifugation after 30 minutes of crystal cultivation. The material was not sticky, and the wet product was dried to obtain 182.5 kg of 2-acrylamide-2-methylpropanesulfonic acid product with a liquid phase purity of 98.52%.

[0022] Example 2

[0023] 5000 kg of 2-acrylamide-2-methylpropanesulfonic acid recrystallization filtrate was added to the distillation kettle, heated in a hot water bath with hot water at 85°C, stirred, added 0.05 kg of p-hydroxyanisole, the distillation temperature in the distillation kettle was 67°C, vacuum distillation was performed, the vacuum degree was ≥ 0.08 MPa, the distillation produced liquid was condensed and stored in a temporary storage tank, and when the material in the kettle became turbid, the hot water heating was turned off and the vacuum was turned off. Within 30 minutes, the above materials were slowly transferred to the crystallization kettle, 1 times of acetic acid was added to the kettle in advance, and the temperature was naturally lowered. After the transfer was completed, the stirring frequency was adjusted to 20HZ, and the temperature was lowered to 15°C for centrifugation after 30 minutes of crystal cultivation. The material was not sticky, and the wet product was dried to obtain 185.1 kg of 2-acrylamide-2-methylpropanesulfonic acid product with a liquid phase purity of 98.68%.

[0024] Example 3

[0025] 5000 kg of 2-acrylamide-2-methylpropanesulfonic acid recrystallization filtrate was added to the distillation kettle, heated in a hot water bath with hot water at 90°C, stirred, added 0.05 kg of p-hydroxyanisole, the distillation temperature in the distillation kettle was 70°C, vacuum distillation was performed, the vacuum degree was ≥ 0.08 MPa, the distillation produced liquid was condensed and stored in a temporary storage tank, and when the material in the kettle became turbid, the hot water heating was turned off and the vacuum was turned off. Within 30 minutes, the above materials were slowly transferred to the crystallization kettle, 1.5 times of acetic acid was added to the kettle in advance, and the temperature was naturally lowered. After the transfer was completed, the stirring frequency was adjusted to 20HZ, and the temperature was lowered to 15°C for centrifugation after 30 minutes of crystal cultivation. The material was not sticky, and the wet product was dried to obtain 184.2 kg of 2-acrylamide-2-methylpropanesulfonic acid product with a liquid phase purity of 98.63%.

[0026] Comparative Example 1

[0027] 5000 kg of 2-acrylamide-2-methylpropanesulfonic acid recrystallization filtrate was added into a distillation kettle, heated in a hot water bath with hot water at 80°C, stirred, added with 0.3 kg of stabilizer p-hydroxyanisole, the distillation temperature in the distillation kettle was 65°C, vacuum distillation was performed, the vacuum degree was ≥0.08 MPa, and the distillation produced liquid was stored in a temporary storage tank after condensation. When the distillation produced ratio was about 60% relative to the weight of the recrystallization filtrate, the distillation was completed, the hot water circulation was turned off, the vacuum was turned off, the temperature was uniformly lowered to 15°C, and then centrifuged. The material was slightly sticky, and the wet product was dried to obtain 155.5 kg of 2-acrylamide-2-methylpropanesulfonic acid product with a liquid phase purity of 96.40%.

[0028] Comparative Example 2

[0029] 5000 kg of 2-acrylamide-2-methylpropanesulfonic acid recrystallization filtrate was added to the distillation kettle, heated in a hot water bath with hot water at 80°C, stirred, added 0.05 kg of stabilizer p-hydroxyanisole, the distillation temperature in the distillation kettle was 67°C, vacuum distillation was performed, the vacuum degree was ≥0.08Mpa, the distillation produced liquid was condensed and stored in a temporary storage tank, and when the material in the kettle became turbid, the hot water heating was turned off and the vacuum was turned off. Slowly add 1 times (relative to the material in the kettle) of acetic acid to the distillation kettle, adjust the stirring frequency to 20HZ, cool to 15°C after crystallization for 30 minutes, then centrifuge, the material is non-sticky, and the wet product is dried to obtain 176.7 kg of 2-acrylamide-2-methylpropanesulfonic acid product with a liquid phase purity of 97.45%.

[0030] Comparative Example 3

[0031] 5000 kg of 2-acrylamide-2-methylpropanesulfonic acid recrystallization filtrate was added to the distillation kettle, heated in a hot water bath with hot water at 90°C, stirred, added 0.05 kg of p-hydroxyanisole, the distillation temperature in the distillation kettle was 70°C, vacuum distillation was performed, the vacuum degree was ≥0.08Mpa, the distillation produced liquid was condensed and stored in a temporary storage tank, and when the material in the kettle became turbid, the hot water heating was turned off and the vacuum was turned off. 1.5 times (relative to the material in the kettle) of acetic acid was slowly added to the distillation kettle, the stirring frequency was adjusted to 20HZ, the temperature was lowered to 15°C after crystallization for 30 minutes, and then centrifuged. The material was slightly sticky, and the wet product was dried to obtain 175.5 kg of 2-acrylamide-2-methylpropanesulfonic acid product with a liquid phase purity of 97.80%.

[0032] The performance indicators of the products recovered from Examples 1-3 and Comparative Examples 1-3 are shown in the following table:

[0033]

[0034] It can be seen from Examples 1-3, Comparative Examples 1-3 and the data in the above table that the product extracted from the recrystallization filtrate of 2-acrylamido-2-methylpropanesulfonic acid by the method of the present invention in Examples 1-3 has a purity of more than 98.5%, good stability, low solvent residue, and high yield.

[0035] By comparing Examples 2 and 3 with Comparative Examples 2 and 3, it can be seen that by adopting the trans-crystallization method of the present invention, compared with the conventional crystallization method of adding acetic acid to the turbid material, the material is less likely to polymerize and become sticky, and the yield will be higher, the product purity will be higher, the stability will be better, and the solvent residue will be lower. This effectively solves the technical problems of easy stickiness of the material, low product purity, low yield, etc. when extracting 2-acrylamide-2-methylpropanesulfonic acid from the recrystallization filtrate by the traditional method, and has great economic value and social value.

[0036] The above description is only an illustrative embodiment of the present invention and is not intended to limit the scope of the present invention. Any equivalent changes and modifications made by any person skilled in the art without departing from the concept and principle of the present invention shall fall within the scope of protection of the present invention.

Claims

1. A method for recovering 2-acrylamido-2-methylpropanesulfonic acid, characterized in that: The steps include: S1, adding the recrystallized filtrate of 2-acrylamide-2-methylpropane sulfonic acid into the first container for vacuum distillation, and adding 0.001% to 0.006% of p-hydroxyanisole relative to the weight of the recrystallized filtrate, the distillation temperature is 50 to 80 ° C, the vacuum degree is ≥ 0.08Mpa, and the material is distilled until it begins to become turbid, then the heating is stopped, the vacuum system is turned off, and the distilled concentrate in the first container is standby; S2, pre-adding acetic acid into the second container, wherein the weight ratio of the acetic acid added to the distilled concentrate in the first container is 0.5 to 3:1; S3, transferring the distillation concentrate in the first container into a second container with an organic solvent, and controlling the transfer time to be 20 to 30 minutes; the distillation concentrate is naturally cooled during the transfer process, and when all the distillation concentrate in the first container is transferred into the second container, the distillation concentrate is grown for 20 to 40 minutes, and then cooled to 10 to 20° C.; thereafter, solid-liquid separation and drying are performed to obtain a 2-acrylamido-2-methylpropanesulfonic acid product.

2. The method for recovering 2-acrylamido-2-methylpropanesulfonic acid according to claim 1, wherein: In step S1, the distillation temperature is 60-70°C.

3. The method for recovering 2-acrylamido-2-methylpropanesulfonic acid according to claim 1, wherein: In step S1, the distillation heating method adopts hot water bath heating, and the hot water bath temperature is 80-90°C.

4. The method for recovering 2-acrylamido-2-methylpropanesulfonic acid according to any one of claims 1 to 3, characterized in that: The first container is a distillation kettle.

5. The method for recovering 2-acrylamido-2-methylpropanesulfonic acid according to any one of claims 1 to 3, characterized in that: The second container is a crystallization kettle.

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