Device and method for continuously preparing 2-acrylamido-2-methylpropanesulfonic acid

Abstract

The invention belongs to the technical field of production processes of chemical products, and relates to a device and a method for continuously preparing 2-acrylamido-2-methylpropanesulfonic acid. The annular pipeline reaction system comprises a crystallization reactor, a tubular reactor group and a mother liquor internal circulation pipeline which form an annular passage; the solid-liquid separation refining system comprises a solid-liquid separation device, a reduced pressure distillation device, a product refining device, a drying device and a heat exchanger; the external circulation and feeding system comprises a mother liquor external circulation pipeline, an isobutene feeding pipeline, a sulfuric acid feeding pipeline, an acrylonitrile feeding pipeline and an acrylonitrile reflux pipeline; the acrylonitrile feeding pipeline is divided into three branches, one branch is connected with the crystallization reactor, one branch is converged with the isobutene feeding pipeline, the mother liquor external circulation pipeline and the acrylonitrile backflow pipeline to be connected with an isobutene feeding port, and the other branch is converged with the sulfuric acid feeding pipeline, the mother liquor external circulation pipeline and the acrylonitrile backflow pipeline to be connected with a sulfuric acid feeding port. According to the invention, the production efficiency is improved, and the yield and purity of the product are higher.

Description

Technical Field

[0001] The present invention belongs to the technical field of production processes for chemical products, and in particular relates to a device and method for continuously preparing 2-acrylamido-2-methylpropanesulfonic acid. Background Art

[0002] 2-Acrylamide-2-methylpropanesulfonic acid (2-Acrylamide-2-methylpropanesulfonic acid) is a versatile, water-soluble anionic monomer present as a white, crystalline solid. Its molecular structure contains a carbon-carbon double bond, a carbonyl group, and a sulfonic acid functional group, resulting in excellent water solubility, salt tolerance, adsorption, and complexing properties. Due to its excellent properties, 2-Acrylamide-2-methylpropanesulfonic acid is currently widely used in industries such as textiles, plastics, wastewater treatment, papermaking, and oil extraction.

[0003] The synthesis method of 2-acrylamido-2-methylpropanesulfonic acid was first described in US Patent No. 2,983,712 of DuPont, USA. This patent uses acryloyl chloride, a primary aliphatic alcohol, and sulfonic acid as the main raw materials for synthesis. In the 1970s, Lubrizol, USA, proposed a two-step production process in which isobutylene was sulfonated to form an intermediate, which was then reacted with acrylonitrile in the presence of water and sulfuric acid to obtain 2-acrylamido-2-methylpropanesulfonic acid. Later, Nitto Chemical Co., Ltd. of Japan proposed a one-step synthesis process in which isobutylene was introduced into a solution of fuming sulfuric acid and acrylonitrile to synthesize 2-acrylamido-2-methylpropanesulfonic acid. This process has mild reaction conditions and readily available raw materials, making it a commonly used production method in modern industrial production. However, this process route is a batch process, with different reaction conditions in each step, requiring complex process operations, high labor intensity, and complex control. This results in a low yield of 2-acrylamido-2-methylpropanesulfonic acid and poor quality stability.

[0004] In 2002, US Pat. No. 6,448,347 proposed a continuous process for synthesizing 2-acrylamido-2-methylpropanesulfonic acid. First, acrylonitrile and fuming sulfuric acid were mixed in a primary reactor and then reacted continuously with isobutylene in a secondary reactor to produce 2-acrylamido-2-methylpropanesulfonic acid. Although this method was stable in operation, it had a low conversion rate and produced a large number of by-products. US Pat. No. 6,504,050 proposed mixing sulfuric acid and phosphoric acid in a first reactor and then reacting with isobutylene and acrylonitrile in a second reactor to produce 2-acrylamido-2-methylpropanesulfonic acid. After filtration and drying, the reaction yield was 89.73%. CN201110246607.4 disclosed a four-reactor continuous synthesis method for 2-acrylamido-2-methylpropanesulfonic acid, with a maximum yield and purity of 97.9% and 98.2%, respectively. Although the continuous process has advantages such as a simple process and ease of operation, controlling impurities during the continuous reaction becomes difficult, and the product contains a large number of residual by-products, resulting in a product that does not achieve the desired yield and purity. Summary of the Invention

[0005] In response to the above-mentioned deficiencies in the prior art, the present invention provides a device and method for continuously preparing 2-acrylamido-2-methylpropanesulfonic acid. The device and method of the present invention not only reduce the content of byproducts in the 2-acrylamido-2-methylpropanesulfonic acid product, enabling the recycling of the raw material acrylonitrile, but also shorten the process flow and improve product production efficiency. Furthermore, the present invention utilizes continuous reaction technology, making operation simpler and product quality more stable, thereby providing a more economical and environmentally friendly preparation process.

[0006] In order to achieve the purpose of the present invention, the first aspect of the present invention provides a device for continuously preparing 2-acrylamido-2-methylpropanesulfonic acid, the device comprising: a ring pipeline reaction system, a solid-liquid separation and refining system, and an external circulation and feeding system;

[0007] The annular pipeline reaction system includes a crystallization reactor, a tubular reactor group and a mother liquid internal circulation pipeline, the three forming an annular passage;

[0008] The solid-liquid separation and refining system includes a solid-liquid separation device, a vacuum distillation device, a product refining device, a drying device and a heat exchanger;

[0009] The external circulation and feeding system includes a mother liquor external circulation pipeline, an isobutylene feeding pipeline, a sulfuric acid feeding pipeline, an acrylonitrile feeding pipeline and an acrylonitrile reflux pipeline;

[0010] The tubular reactor group includes a plurality of tubular reactors arranged vertically and in parallel, each tubular reactor includes at least one sulfuric acid feed port and at least one isobutylene feed port, and the sulfuric acid feed port is located above the isobutylene feed port. The acrylonitrile feed line is divided into three branches, one of which is connected to the crystallization reactor, another is connected to the isobutylene feed port after merging with the isobutylene feed line, and the last is connected to the sulfuric acid feed port after merging with the sulfuric acid feed line;

[0011] The crystallization reactor is provided with a crystallization reactor overflow outlet pipeline, the crystallization reactor overflow outlet pipeline is divided into two branches, one of which serves as a mother liquor external circulation pipeline, and the other is connected to a solid-liquid separation device, the solid-liquid separation device is provided with a solid-phase discharge pipeline and a solid-liquid separation device liquid-phase discharge pipeline, the solid-liquid separation device solid-phase discharge pipeline is sequentially connected to a product refining device and a drying device, the drying device is provided with a product discharge port, the solid-liquid separation device liquid-phase discharge pipeline is connected to a vacuum distillation device and a heat exchanger and then divided into two branches, one of which serves as an acrylonitrile reflux pipeline, and the other is connected to the product refining device;

[0012] After the mother liquor external circulation pipeline and the acrylonitrile reflux pipeline are merged, they are divided into two branches, which are respectively connected to the isobutylene feed port and the sulfuric acid feed port.

[0013] A second aspect of the present invention provides a method for continuously preparing 2-acrylamido-2-methylpropanesulfonic acid, which is carried out using the apparatus for continuously preparing 2-acrylamido-2-methylpropanesulfonic acid, and comprises the following steps:

[0014] Step 1: adding the first portion of acrylonitrile as an initial mother liquor into a crystallization reactor, and the mother liquor enters each tubular reactor through an internal circulation line of the mother liquor; isobutylene and the second portion of acrylonitrile are mixed, and then enter each tubular reactor through an isobutylene feed port; sulfuric acid and the third portion of acrylonitrile are mixed, and then enter each tubular reactor through a sulfuric acid feed port; the isobutylene, sulfuric acid, and acrylonitrile react in the tubular reactor to obtain a crude product;

[0015] Step 2: The crude product obtained in step 1 enters a crystallization reactor, is mixed with the initial mother liquor, and matured. A portion of the crude product is returned to each tubular reactor via the mother liquor internal circulation pipeline as an internal circulation mother liquor, and the other portion flows out of the overflow port of the crystallization reactor and is divided into two portions, one portion of which is used as an external circulation mother liquor, and the other portion enters a solid-liquid separation device for solid-liquid separation;

[0016] In step 3, the liquid phase obtained by the solid-liquid separation device is sent to a vacuum distillation device for vacuum distillation to obtain vaporized acrylonitrile. After condensation in a heat exchanger, a portion is sent to a product refining device, and the other portion is used as reflux acrylonitrile and mixed with an external circulation mother liquor and then divided into two parts, which enter each tubular reactor through an isobutylene feed port and a sulfuric acid feed port respectively. The solid phase obtained by the solid-liquid separation device is sequentially sent to a product refining device and a drying device for washing, filtering and drying to obtain a 2-acrylamido-2-methylpropanesulfonic acid product.

[0017] The continuous production device and method of the present invention are simple to operate, shorten the reaction time, improve the production efficiency, and have higher yield and purity of the product.

[0018] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Exemplary embodiments of the present invention will be described in more detail with reference to the accompanying drawings.

[0020] Figure 1 The figure shows a schematic diagram of a device for continuously preparing 2-acrylamido-2-methylpropanesulfonic acid provided by the present invention.

[0021] Description of Reference Numerals

[0022] 1-Crystallization reactor 2-Solid-liquid separation device

[0023] 3- Vacuum distillation unit 4- Product refining unit

[0024] 5-Drying device 6, 23-Heat exchanger

[0025] 7-Sulfuric acid static mixer 8-Isobutylene static mixer

[0026] 9-Mixer internals 10-Tubular reactor

[0027] 11-mother liquor internal circulation pipeline 12,13,14,21,22-flow pump

[0028] 15-Mother liquor external circulation pipeline 16-Isobutylene feed pipeline

[0029] 17- sulfuric acid feed line 18- acrylonitrile feed line

[0030] 19-Acrylonitrile reflux line 20-Product discharge port DETAILED DESCRIPTION

[0031] The following is a detailed description of the specific embodiments of the present invention. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention and are not intended to limit the present invention.

[0032] In order to achieve the purpose of the present invention, the first aspect of the present invention provides a device for continuously preparing 2-acrylamido-2-methylpropanesulfonic acid, the device comprising: a ring pipeline reaction system, a solid-liquid separation and refining system, and an external circulation and feeding system;

[0033] The annular pipeline reaction system includes a crystallization reactor 1, a tubular reactor group and a mother liquid internal circulation pipeline 11, the three forming an annular passage;

[0034] The solid-liquid separation and refining system includes a solid-liquid separation device 2, a vacuum distillation device 3, a product refining device 4, a drying device 5 and a heat exchanger 6;

[0035] The external circulation and feeding system includes a mother liquor external circulation pipeline 15, an isobutylene feeding pipeline 16, a sulfuric acid feeding pipeline 17, an acrylonitrile feeding pipeline 18 and an acrylonitrile reflux pipeline 19;

[0036] The tubular reactor group includes a plurality of tubular reactors 10 arranged vertically and in parallel, each tubular reactor 10 includes at least one sulfuric acid feed port and at least one isobutylene feed port, and the sulfuric acid feed port is located above the isobutylene feed port. The acrylonitrile feed line 18 is divided into three branches, one of which is connected to the crystallization reactor 1, another is connected to the isobutylene feed port after merging with the isobutylene feed line 16, and the last is connected to the sulfuric acid feed port after merging with the sulfuric acid feed line 17;

[0037] The crystallization reactor 1 is provided with a crystallization reactor overflow outlet pipeline, the crystallization reactor overflow outlet pipeline is divided into two branches, one of which serves as a mother liquor external circulation pipeline 15, and the other is connected to the solid-liquid separation device 2, the solid-liquid separation device 2 is provided with a solid-liquid separation device solid phase discharge pipeline and a solid-liquid separation device liquid phase discharge pipeline, the solid-liquid separation device solid phase discharge pipeline is sequentially connected to the product refining device 4 and the drying device 5, the drying device 5 is provided with a product discharge port 20, the solid-liquid separation device liquid phase discharge pipeline is connected to the vacuum distillation device 3 and the heat exchanger 6 and then divided into two branches, one of which serves as an acrylonitrile reflux pipeline 19, and the other is connected to the product refining device 4;

[0038] After the mother liquor external circulation pipeline 15 and the acrylonitrile reflux pipeline 19 are merged, they are divided into two branches, which are respectively connected to the isobutylene feed port and the sulfuric acid feed port.

[0039] The production process of 2-acrylamido-2-methylpropanesulfonic acid provided by the present invention has a parallel arrangement of reaction sections and parallel multi-point feeding, which can minimize the generation of by-products. By arranging a mother liquor internal circulation system, only axial mixing is achieved in the reactor without radial back-mixing, and the residence time is uniform, thereby improving the utilization efficiency of the mother liquor and achieving both energy saving and high efficiency. In addition, since the dissolution of isobutylene is a reaction-controlling step, the process arranges the isobutylene feed port below the sulfuric acid feed port, and promotes the dispersion of isobutylene by regulating the flow rate of the circulating mother liquor and arranging the internal components of the static mixer, thereby ensuring the full dissolution of isobutylene and accelerating the reaction process. The inventors have also found through research that, when the isobutylene and sulfuric acid feed amounts are fixed, the conversion rate of sulfuric acid increases with the increase of the isobutylene feed points, which can effectively improve the conversion rate of the reaction.

[0040] In the present invention, the solid-liquid separation method can be any method that can achieve solid-liquid separation, such as filtration method, including atmospheric pressure filtration method, vacuum filtration method, centrifugal separation, etc.

[0041] In the present invention, the solid-liquid separation device, the reduced pressure distillation device and the vacuum drying device can be conventional devices for solid-liquid separation (such as a centrifugal filter), the reduced pressure distillation device (rotary evaporator) and the vacuum drying device (such as a vacuum oven).

[0042] According to the present invention, preferably, the tubular reactor is a straight-through tubular structure, the inner diameter of the tube is 0.5 mm-10 mm, preferably 4 mm-6 mm, and the length of the tube is 0.5 m-5 m, preferably 1 m-3 m.

[0043] Preferably, a flow pump is provided at the bottom of each tubular reactor, on the confluence line of the mother liquor external circulation pipeline 15 and the acrylonitrile reflux pipeline 19, and on the pipeline connecting the confluence line of the mother liquor external circulation pipeline 15 and the acrylonitrile reflux pipeline 19 and the isobutylene feed port, for controlling the flow rate of the circulating mother liquor.

[0044] Preferably, each sulfuric acid feed port and each isobutylene feed port are provided with a control valve and a metering instrument.

[0045] According to the present invention, preferably, the external circulation feeding system further includes a sulfuric acid static mixer 7 , an isobutylene static mixer 8 and a heat exchanger 23 .

[0046] Preferably, the confluent pipeline of the mother liquor external circulation line 15 and the acrylonitrile reflux line 19 is divided into two branches, one of which is connected to the isobutylene feed line 16 and then sequentially connected to the heat exchanger 23, the isobutylene static mixer 8 and the isobutylene feed port, and the other is connected to the sulfuric acid static mixer 7 and the sulfuric acid feed port after merging with the sulfuric acid feed line 17.

[0047] According to the present invention, preferably, the product refining device 4 is further provided with a product refining device liquid phase discharge pipeline, and the product refining device liquid phase discharge pipeline is connected to the vacuum distillation device 3.

[0048] Preferably, the materials of the crystallization reactor 1 , the tubular reactor and the mother liquid circulation reflux pipe 11 are independently selected from at least one of glass, enamel and fluoropolymer.

[0049] Preferably, the product refining device 4 is a solid-liquid separation device with a spray system, preferably a spray filter.

[0050] According to the present invention, preferably, the number of tubular reactors is 3-8, and the number of tubular reactors used and the flow rate of the internal circulating mother liquor can be controlled according to production needs, thereby achieving the purpose of controlling the reaction scale and reaction process.

[0051] According to the present invention, preferably, each tubular reactor is provided with at least two static mixer internals. At least two static mixer internals are provided in each tubular reactor to enhance mass transfer, enhance the mixing effect of sulfuric acid, isobutylene and acrylonitrile, and improve reaction efficiency. Preferably, the structure of the static mixer internals is a ridge-shaped structure, and the material is organic glass or polytetrafluoroethylene.

[0052] According to the present invention, preferably, each tubular reactor has 1 to 2 sulfuric acid feed ports, each tubular reactor has 1 to 2 isobutylene feed ports, and the isobutylene feed port is arranged below the sulfuric acid feed port. By connecting multiple tubular reactors in parallel, multi-point feeding of sulfuric acid and isobutylene is achieved, which helps to uniformly mix the two, improve reaction efficiency, and reduce side reactions.

[0053] A second aspect of the present invention provides a method for continuously preparing 2-acrylamido-2-methylpropanesulfonic acid, which is carried out using the apparatus for continuously preparing 2-acrylamido-2-methylpropanesulfonic acid, and comprises the following steps:

[0054] Step 1: Add the first portion of acrylonitrile as an initial mother liquor into a crystallization reactor 1, and the mother liquor enters each tubular reactor 10 through a mother liquor internal circulation line 11; after isobutylene and the second portion of acrylonitrile are mixed, they enter each tubular reactor through an isobutylene feed port; after sulfuric acid and the third portion of acrylonitrile are mixed, they enter each tubular reactor through a sulfuric acid feed port; the isobutylene, sulfuric acid, and acrylonitrile react in the tubular reactor to obtain a crude product;

[0055] Step 2: The crude product obtained in step 1 enters the crystallization reactor 1, is mixed with the initial mother liquor, and matured. A portion of the crude product is returned to each tubular reactor 10 via the mother liquor internal circulation pipeline 11 as the internal circulation mother liquor, and the other portion flows out of the overflow port of the crystallization reactor 1 and is divided into two portions, one portion of which is used as the external circulation mother liquor, and the other portion enters the solid-liquid separation device 2 for solid-liquid separation;

[0056] In step 3, the liquid phase obtained by the solid-liquid separator 2 is fed to a vacuum distillation device 3 for vacuum distillation to obtain vaporized acrylonitrile. After condensation in a heat exchanger 6, a portion is fed to a product refining device 4, and the other portion is mixed with an external circulating mother liquor as reflux acrylonitrile and then divided into two portions, which enter each tubular reactor through an isobutylene feed port and a sulfuric acid feed port, respectively. The solid phase obtained by the solid-liquid separator 2 is sequentially fed to a product refining device 4 and a drying device 5 for washing, filtering, and drying to obtain a 2-acrylamido-2-methylpropanesulfonic acid product.

[0057] According to the present invention, preferably, the operating conditions in the crystallization reactor 1 include: a temperature of 30-50° C., preferably 35-45° C., a residence time of 0.5-3 h, preferably 1-2 h;

[0058] The operating conditions of the vacuum distillation device 3 include: vacuum degree ≥ 0.08 MPa, temperature 40-50°C;

[0059] The operating conditions of the drying device 5 include: a temperature of 50-80° C., preferably 70-80° C., and a vacuum degree ≥ 0.08 MPa.

[0060] According to the present invention, preferably, the sulfuric acid is fuming sulfuric acid, and the concentration of the fuming sulfuric acid is 98%-103%, preferably 100%-102%;

[0061] The isobutylene and the second portion of acrylonitrile are initially mixed in a molar ratio of 1:(2-10), preferably 1:(2-5), and the mixing temperature is 30-50° C., preferably 35-45° C.;

[0062] The molar ratio of the sulfuric acid and the third part of acrylonitrile when initially mixed is 1:(1-5), preferably 1:(1-3), and the mixing temperature is -10 to 20°C, preferably -5 to 5°C;

[0063] The molar ratio of isobutylene to sulfuric acid feed is 1:(1-5), preferably 1:(1-2).

[0064] According to the present invention, preferably, the content of 2-acrylamido-2-methylpropanesulfonic acid in the 2-acrylamido-2-methylpropanesulfonic acid product is ≥99% by weight.

[0065] The present invention will be further described below with reference to the examples, but the scope of the present invention is not limited to these examples.

[0066] In the following embodiments:

[0067] The purity of the crude and pure 2-acrylamido-2-methylpropanesulfonic acid was determined by liquid chromatography using a Zorbax SAX column, a 0.1 mol / L KH2PO4 solution as the mobile phase, a flow rate of 1.0 mL / min, and a UV detector.

[0068] Yield of 2-acrylamido-2-methylpropanesulfonic acid = number of moles of 2-acrylamido-2-methylpropanesulfonic acid in the product / number of moles of isobutylene × 100%.

[0069] In the following examples and comparative examples, fuming sulfuric acid (with a concentration of 102%) was used as sulfuric acid, and analytically pure acrylonitrile (with a water content of 0.5% by weight) was used as acrylonitrile.

[0070] Example 1

[0071] This embodiment adopts Figure 1 The device for continuously preparing 2-acrylamido-2-methylpropanesulfonic acid is shown, which includes: a ring pipeline reaction system, a solid-liquid separation and refining system, and an external circulation and feeding system;

[0072] The annular pipeline reaction system includes a crystallization reactor 1, three parallel tubular reactors 10 and a mother liquor internal circulation pipeline 11, which form an annular passage; two static mixer internal components are set in each tubular reactor, and the inner diameter of the tubular reactor tube is 4mm and the length is 2m;

[0073] The solid-liquid separation and refining system includes a solid-liquid separation device 2, a vacuum distillation device 3, a product refining device 4, a drying device 5 and a heat exchanger 6;

[0074] The external circulation and feeding system includes a mother liquor external circulation pipeline 15, an isobutylene feeding pipeline 16, a sulfuric acid feeding pipeline 17, an acrylonitrile feeding pipeline 18 and an acrylonitrile reflux pipeline 19;

[0075] Each tubular reactor 10 includes two sulfuric acid feed ports and two isobutylene feed ports, and the sulfuric acid feed ports are all located above the isobutylene feed port. The acrylonitrile feed line 18 is divided into three branches, one of which is connected to the crystallization reactor 1, another is connected to the isobutylene feed port after merging with the isobutylene feed line 16, and the last is connected to the sulfuric acid feed port after merging with the sulfuric acid feed line 17;

[0076] The crystallization reactor 1 is provided with a crystallization reactor overflow outlet pipeline, the crystallization reactor overflow outlet pipeline is divided into two branches, one of which serves as a mother liquor external circulation pipeline 15, and the other is connected to the solid-liquid separation device 2, the solid-liquid separation device 2 is provided with a solid-liquid separation device solid phase discharge pipeline and a solid-liquid separation device liquid phase discharge pipeline, the solid-liquid separation device solid phase discharge pipeline is sequentially connected to the product refining device 4 and the drying device 5, the drying device 5 is provided with a product discharge port 20, the solid-liquid separation device liquid phase discharge pipeline is connected to the vacuum distillation device 3 and the heat exchanger 6 and then divided into two branches, one of which serves as an acrylonitrile reflux pipeline 19, and the other is connected to the product refining device 4;

[0077] After the mother liquor external circulation pipeline 15 and the acrylonitrile reflux pipeline 19 are merged, they are divided into two branches, which are respectively connected to the isobutylene feed port and the sulfuric acid feed port;

[0078] Flow pumps are provided at the bottom of each tubular reactor, on the confluence line of the mother liquor external circulation pipeline 15 and the acrylonitrile reflux pipeline 19, and on the pipeline connecting the confluence line of the mother liquor external circulation pipeline 15 and the acrylonitrile reflux pipeline 19 and the isobutylene feed port.

[0079] The method for continuously preparing 2-acrylamido-2-methylpropanesulfonic acid is as follows:

[0080] Step 1: Add 1000g of acrylonitrile as an initial mother liquor into a crystallization reactor 1, and enter each tubular reactor 10 at a flow rate of 300g / min through a mother liquor internal circulation line 11. The reactor temperature is controlled at 35°C. Isobutylene and the second part of acrylonitrile are mixed at speeds of 21g / min and 56g / min, and then passed into an isobutylene static mixer 8. The mixer temperature is 35°C, and then the mixture enters each tubular reactor through an isobutylene feed port. Sulfuric acid and the third part of acrylonitrile are mixed at speeds of 35g / min and 56g / min, and then passed into a sulfuric acid static mixer 7. The mixer temperature is 5°C, and then the mixture enters each tubular reactor through a sulfuric acid feed port. Isobutylene, sulfuric acid and acrylonitrile react in the tubular reactor to obtain a crude product.

[0081] Step 2: The crude product obtained in step 1 enters the crystallization reactor 1 and is mixed with the initial mother liquor and matured. A portion of the crude product is returned to each tubular reactor 10 via the mother liquor internal circulation pipeline 11 as the internal circulation mother liquor, and the other portion flows out of the overflow port of the crystallization reactor 1 and is divided into two parts, one of which is used as the external circulation mother liquor, and the other portion enters the solid-liquid separation device 2 for solid-liquid separation; during operation, the flow rate of the mother liquor and the refluxed acrylonitrile in the external circulation pipeline is adjusted by controlling each circulation flow pump on the pipeline to maintain a stable liquid level in the crystallization reactor, and the residence time of the reactants in the crystallization reactor is controlled to be 1 hour.

[0082] In step 3, the liquid phase obtained by the solid-liquid separator 2 is fed into a vacuum distillation apparatus 3 for vacuum distillation to obtain vaporized acrylonitrile. After condensation in a heat exchanger 6, a portion is fed into a product refining apparatus 4, and the other portion is mixed with an external circulation mother liquor as reflux acrylonitrile and then divided into two portions, which enter each tubular reactor through an isobutylene feed port and a sulfuric acid feed port, respectively. The solid phase obtained by the solid-liquid separator 2 is sequentially fed into a product refining apparatus 4 and a drying apparatus 5 for washing, filtering, and drying to obtain a 2-acrylamido-2-methylpropanesulfonic acid product. Parameters such as the purity and impurity content of the product are shown in Table 1.

[0083] Example 2

[0084] 2-Acrylamido-2-methylpropanesulfonic acid was prepared according to the method described in Example 1, except that the flow rates of isobutylene and acrylonitrile during initial mixing were 21 g / min and 94 g / min, respectively, and the flow rates of fuming sulfuric acid and acrylonitrile during initial mixing were 35 g / min and 19 g / min, respectively. The purity and impurity content of the resulting 2-acrylamido-2-methylpropanesulfonic acid product are shown in Table 1.

[0085] Example 3

[0086] 2-Acrylamido-2-methylpropanesulfonic acid was prepared according to the method described in Example 1, except that the temperature of the isobutylene static mixer was 45°C and the temperature of the sulfuric acid static mixer was -5°C. The purity and impurity content of the final 2-acrylamido-2-methylpropanesulfonic acid product are shown in Table 1.

[0087] Example 4

[0088] 2-Acrylamido-2-methylpropanesulfonic acid was prepared according to the method described in Example 1, except that the residence time of the reactants in the crystallization reactor was controlled to 2 hours by regulating the various circulation flow pumps in the pipeline. The purity and impurity content of the final 2-acrylamido-2-methylpropanesulfonic acid product are shown in Table 1.

[0089] Example 5

[0090] 2-Acrylamido-2-methylpropanesulfonic acid was prepared according to the method described in Example 1, except that the tubular reactor had an inner diameter of 6 mm and a length of 1 m. The product parameters and impurity content of the resulting pure 2-acrylamido-2-methylpropanesulfonic acid are shown in Table 1.

[0091] Example 6

[0092] 2-Acrylamido-2-methylpropanesulfonic acid was prepared according to the method described in Example 1, except that an isobutylene feed port was added to each tubular reactor. The purity and impurity content of the final 2-acrylamido-2-methylpropanesulfonic acid product are shown in Table 1.

[0093] Example 7

[0094] 2-Acrylamido-2-methylpropanesulfonic acid was prepared according to the method described in Example 1, except that the reaction section consisted of four tubular reactors. The purity and impurity content of the final 2-acrylamido-2-methylpropanesulfonic acid product are shown in Table 1.

[0095] Table 1

[0096]

[0097] As can be seen from Table 1, the method for continuously preparing 2-acrylamido-2-methylpropanesulfonic acid of the present invention can obtain a 2-acrylamido-2-methylpropanesulfonic acid product with low residual by-products, high yield, and a purity of ≥99 wt%.

[0098] While various embodiments of the present invention have been described above, the above description is intended to be illustrative, not exhaustive, and not limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

[0099] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

Claims

1. A device for continuously preparing 2-acrylamido-2-methylpropanesulfonic acid, characterized in that: The device comprises: a ring pipeline reaction system, a solid-liquid separation and refining system, and an external circulation and feeding system; The annular pipeline reaction system comprises a crystallization reactor (1), a tubular reactor group and a mother liquid internal circulation pipeline (11), the three forming an annular passage; The solid-liquid separation and refining system comprises a solid-liquid separation device (2), a vacuum distillation device (3), a product refining device (4), a drying device (5) and a heat exchanger (6); The external circulation and feeding system includes a mother liquor external circulation pipeline (15), an isobutylene feeding pipeline (16), a sulfuric acid feeding pipeline (17), an acrylonitrile feeding pipeline (18) and an acrylonitrile reflux pipeline (19); The tubular reactor group comprises a plurality of tubular reactors (10) vertically and in parallel, each tubular reactor (10) comprising at least one sulfuric acid feed port and at least one isobutylene feed port, and the sulfuric acid feed ports are all located above the isobutylene feed port, the acrylonitrile feed line (18) is divided into three branches, one of which is connected to the crystallization reactor (1), another is connected to the isobutylene feed port after merging with the isobutylene feed line (16), and the last is connected to the sulfuric acid feed port after merging with the sulfuric acid feed line (17); The crystallization reactor (1) is provided with a crystallization reactor overflow outlet pipeline, the crystallization reactor overflow outlet pipeline is divided into two branches, one of which serves as a mother liquid external circulation pipeline (15), and the other is connected to the solid-liquid separation device (2), the solid-liquid separation device (2) is provided with a solid-phase discharge pipeline of the solid-liquid separation device and a liquid-phase discharge pipeline of the solid-liquid separation device, the solid-phase discharge pipeline of the solid-liquid separation device is sequentially connected to the product refining device (4) and the drying device (5), the drying device (5) is provided with a product discharge port (20), the liquid-phase discharge pipeline of the solid-liquid separation device is connected to the vacuum distillation device (3) and the heat exchanger (6) and then divided into two branches, one of which serves as an acrylonitrile reflux pipeline (19), and the other is connected to the product refining device (4); After the mother liquor external circulation pipeline (15) and the acrylonitrile reflux pipeline (19) are merged, they are divided into two branches, which are respectively connected to the isobutylene feed port and the sulfuric acid feed port.

2. The device for continuously preparing 2-acrylamido-2-methylpropanesulfonic acid according to claim 1, wherein: The tubular reactor is a straight-through tubular structure, the inner diameter of the tube is 0.5 mm to 10 mm, preferably 4 mm to 6 mm, and the length of the tube is 0.5 m to 5 m, preferably 1 m to 3 m.

3. The device for continuously preparing 2-acrylamido-2-methylpropanesulfonic acid according to claim 1, wherein: The number of the tubular reactors is 3-8; Flow pumps are provided at the bottom of each tubular reactor, on the confluence line of the mother liquid external circulation pipeline (15) and the acrylonitrile reflux pipeline (19), and on the pipeline connecting the confluence line of the mother liquid external circulation pipeline (15) and the acrylonitrile reflux pipeline (19) and the isobutylene feed port; Each sulfuric acid feed port and each isobutylene feed port are provided with a control valve and a metering instrument; preferably, each tubular reactor has 1 to 2 sulfuric acid feed ports, and each tubular reactor has 1 to 2 isobutylene feed ports.

4. The device for continuously preparing 2-acrylamido-2-methylpropanesulfonic acid according to claim 1, wherein: The external circulation feeding system further includes a sulfuric acid static mixer (7), an isobutylene static mixer (8) and a heat exchanger (23); The merging pipeline of the mother liquor external circulation pipeline (15) and the acrylonitrile reflux pipeline (19) is divided into two branches, one of which is connected to the isobutylene feed pipeline (16) and then sequentially connected to the heat exchanger (23), the isobutylene static mixer (8) and the isobutylene feed port, and the other is connected to the sulfuric acid feed pipeline (17) and then sequentially connected to the sulfuric acid static mixer (7) and the sulfuric acid feed port.

5. The device for continuously preparing 2-acrylamido-2-methylpropanesulfonic acid according to claim 1, wherein: The product refining device (4) is further provided with a product refining device liquid phase discharge pipeline, and the product refining device liquid phase discharge pipeline is connected to the vacuum distillation device (3).

6. The device for continuously preparing 2-acrylamido-2-methylpropanesulfonic acid according to claim 1, wherein: Each tubular reactor is provided with at least two static mixer internals. Preferably, the static mixer internals have a ridge-shaped structure and are made of organic glass or polytetrafluoroethylene. The materials of the crystallization reactor (1), the tubular reactor and the mother liquid circulation reflux pipe (11) are independently selected from at least one of glass, enamel and fluoropolymer; The product refining device (4) is a solid-liquid separation device with a spray system, preferably a spray filter.

7. A method for continuously preparing 2-acrylamido-2-methylpropanesulfonic acid, characterized in that: The steps include: Step 1: Add the first portion of acrylonitrile as an initial mother liquor into a crystallization reactor (1), and enter each tubular reactor (10) through a mother liquor internal circulation line (11); after isobutylene and the second portion of acrylonitrile are mixed, they enter each tubular reactor through an isobutylene feed port; after sulfuric acid and the third portion of acrylonitrile are mixed, they enter each tubular reactor through a sulfuric acid feed port; the isobutylene, sulfuric acid, and acrylonitrile react in the tubular reactor to obtain a crude product; Step 2: The crude product obtained in step 1 enters the crystallization reactor (1) and is mixed with the initial mother liquor and matured. A portion of the crude product is returned to each tubular reactor (10) via the mother liquor internal circulation pipeline (11) as the internal circulation mother liquor. The other portion flows out of the overflow port of the crystallization reactor (1) and is divided into two portions, one portion of which is used as the external circulation mother liquor, and the other portion enters the solid-liquid separation device (2) for solid-liquid separation. In step 3, the liquid phase obtained by the solid-liquid separation device (2) is sent to a vacuum distillation device (3) for vacuum distillation to obtain vaporized acrylonitrile. After condensation in a heat exchanger (6), a portion is sent to a product refining device (4), and the other portion is mixed with an external circulation mother liquor as reflux acrylonitrile and then divided into two portions, which enter each tubular reactor through an isobutylene feed port and a sulfuric acid feed port respectively. The solid phase obtained by the solid-liquid separation device (2) is sequentially sent to a product refining device (4) and a drying device (5) for washing, filtering and drying to obtain a 2-acrylamido-2-methylpropanesulfonic acid product.

8. The method for continuously preparing 2-acrylamido-2-methylpropanesulfonic acid according to claim 7, wherein: The operating conditions in the crystallization reactor (1) include: a temperature of 30-50°C, preferably 35-45°C, a residence time of 0.5-3h, preferably 1-2h; The operating conditions of the vacuum distillation device (3) include: vacuum degree ≥ 0.08 MPa, temperature 40-50°C; The operating conditions of the drying device (5) include: a temperature of 50-80°C, preferably 70-80°C, and a vacuum degree ≥0.08Mpa.

9. The method for continuously preparing 2-acrylamido-2-methylpropanesulfonic acid according to claim 7, wherein: The sulfuric acid is fuming sulfuric acid, and the concentration of the fuming sulfuric acid is 98%-103%, preferably 100%-102%.

10. The method for continuously preparing 2-acrylamido-2-methylpropanesulfonic acid according to claim 7, wherein: The isobutylene and the second portion of acrylonitrile are initially mixed in a molar ratio of 1:(2-10), preferably 1:(2-5), and the mixing temperature is 30-50° C., preferably 35-45° C.; The molar ratio of the sulfuric acid and the third part of acrylonitrile when initially mixed is 1:(1-5), preferably 1:(1-3), and the mixing temperature is -10 to 20°C, preferably -5 to 5°C; The molar ratio of isobutylene to sulfuric acid feed is 1:(1-5), preferably 1:(1-2).

11. The method for continuously preparing 2-acrylamido-2-methylpropanesulfonic acid according to claim 7, wherein: The content of 2-acrylamido-2-methylpropanesulfonic acid in the 2-acrylamido-2-methylpropanesulfonic acid product is ≥99% by weight.

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