Method for producing acrylamide monomer solution

Abstract

The invention discloses an acrylamide monomer solution production method which comprises the following steps: adding acrylonitrile, water and immobilized nitrile hydratase into a reaction kettle for hydration reaction to prepare an acrylamide monomer; the reaction kettle comprises a kettle body, a kettle cover is arranged at the upper end of the kettle body, a discharging pipe is arranged at the bottom of the kettle body, a first feeding pipe, a second feeding pipe, a third feeding pipe and a stirring motor are arranged on the kettle cover, a stirring shaft is arranged on an output shaft of the stirring motor, and stirring paddles are distributed on the stirring shaft; an annular distributor is further arranged in the kettle body and comprises a distribution cavity, the upper end of the distribution cavity is connected with an adjusting cavity, a spraying head is arranged in the adjusting cavity and provided with spraying holes communicated with the distribution cavity, the distribution cavity is communicated with the bottom of the kettle body through a circulating pipe, and a circulating pump is arranged on the circulating pipe. According to the method disclosed by the invention, acrylonitrile is hydrolyzed by using the immobilized nitrile hydratase with high stability, so that the problems of relatively poor enzyme stability and relatively high production cost in preparation of acrylamide by an existing biological catalysis method are solved.

Description

Technical Field

[0001] The invention relates to the technical field of acrylamide production, in particular to a method for producing an acrylamide monomer solution. Background Art

[0002] Acrylamide is an important chemical intermediate, widely used in the production of polyacrylamide, flocculants, sewage treatment agents, papermaking and textile auxiliaries, etc. There are two main preparation methods: chemical method and biocatalytic method.

[0003] The chemical method for preparing acrylamide mainly includes the nitrile hydration method and the hydrolysis method. The nitrile hydration method uses acrylonitrile as the raw material, and hydrolyzes acrylonitrile into acrylamide in an acidic medium under the catalysis of copper sulfate; the hydrolysis method is that acrylonitrile directly reacts with water to generate acrylamide, which is usually carried out under high temperature and high pressure conditions. The existing chemical method for preparing acrylamide has problems such as many by-products, greater environmental pollution and high energy consumption.

[0004] The biocatalytic method for preparing acrylamide mainly includes the enzyme catalytic method and the microbial catalytic method. The enzyme catalytic method is to use nitrile hydratase to directly hydrolyze acrylonitrile to acrylamide; the microbial catalytic method is to use microorganisms that can produce nitrile hydratase to catalyze the hydrolysis of acrylonitrile to produce acrylamide. The existing biocatalytic method for preparing acrylamide has problems such as poor enzyme stability and high production cost. Summary of the invention

[0005] Based on the technical problems existing in the background technology, the present invention proposes a method for producing acrylamide monomer solution, in which acrylonitrile is hydrolyzed by immobilized nitrile hydratase with high stability, thereby solving the problems of poor enzyme stability and high production cost in the existing biocatalytic method for preparing acrylamide.

[0006] The method for producing acrylamide monomer solution provided by the present invention comprises the following steps: adding acrylonitrile, water and immobilized nitrile hydratase into a reaction kettle for hydration reaction to obtain acrylamide monomer;

[0007] The method steps for preparing the immobilized nitrile hydratase are as follows:

[0008] S1: Dissolve nickel salt, cobalt salt and cysteine ​​in deionized water respectively;

[0009] S2: dissolving 1-H-3,5-pyrazoledicarboxylic acid monohydrate in dimethyl sulfoxide;

[0010] S3: mixing the nickel salt solution and the cobalt salt solution, adding them to the cysteine ​​solution and mixing them evenly;

[0011] S4: adding the 1-H-3,5-pyrazoledicarboxylic acid monohydrate solution of S2 to the mixed solution of S3 to react, and obtaining a catalyst support after filtering and vacuum drying;

[0012] S5: The catalyst carrier is dispersed in PBS buffer, and then nitrile hydratase is added, stirred and then allowed to stand to obtain immobilized nitrile hydratase.

[0013] Preferably, the volume ratio of acrylonitrile to water is 1:3-5, and the addition amount of the immobilized nitrile hydratase is 0.05-0.15% of the total mass of acrylonitrile and water.

[0014] Preferably, the hydration reaction temperature is 18-25°C and the time is 5-10h.

[0015] Preferably, the nickel salt in S1 is one or more of nickel nitrate, nickel acetate, nickel sulfate, and nickel chloride; the cobalt salt is one or more of cobalt nitrate, cobalt acetate, cobalt sulfate, and cobalt chloride; and the cysteine ​​is L-cysteine.

[0016] Preferably, the molar ratio of 1-H-3,5-pyrazoledicarboxylic acid monohydrate, nickel salt, cobalt salt and cysteine ​​is 1:0.3-0.5:0.3-0.5:0.05-0.15.

[0017] Preferably, the reaction temperature in S4 is 20-30°C and the time is 12-36h; the vacuum drying temperature is 30-40°C and the time is 1-3h.

[0018] Preferably, in S5, the stirring time is 5-10 h, the stirring rate is 100-300 rpm, the standing time is 10-14 h, and the standing temperature is 0-35°C.

[0019] Preferably, the reaction kettle comprises a kettle body with an opening at the upper end, a kettle cover is detachably provided at the opening at the upper end of the kettle body, a discharge pipe is provided at the bottom of the kettle body, a first feed pipe, a second feed pipe, a third feed pipe and a stirring motor are provided on the kettle cover, a stirring shaft is fixedly provided on the output shaft of the stirring motor, and a plurality of stirring paddles are evenly distributed on the stirring shaft located in the kettle body;

[0020] An annular distributor is also provided in the kettle body, and the distributor includes a distribution cavity, and a plurality of evenly distributed regulating cavities are connected to the upper end of the distribution cavity. A spray head is detachably provided in the regulating cavity, and the spray head is provided with a spray hole connected to the distribution cavity. The distribution cavity is connected to the bottom of the kettle body through a circulation pipe, and a circulation pump is provided on the circulation pipe.

[0021] Preferably, the stirring paddles are distributed above and below the distributor.

[0022] Preferably, the stirring speed N of the stirring shaft is determined according to the following formula:

[0023] N=300·Q α ·sin(θ+θ0) β

[0024] Where Q is the circulation pump flow rate; θ is the injection hole inclination angle; θ0 is the angle correction value; α is the circulation pump flow rate influence index; β is the injection hole inclination angle influence index.

[0025] Beneficial technical effects of the present invention:

[0026] (1) The present invention utilizes nickel and cobalt to synthesize a bimetallic organic framework, which can optimize the electronic structure of MOF by regulating the electronic interaction between metal ions. This electronic regulation can affect the conductivity and electron density distribution of MOF, thereby improving the electron transfer efficiency between the enzyme and the matrix; in addition, the nickel and cobalt bimetallic centers can enhance the stability and catalytic performance of MOF through synergistic effects. Nickel and cobalt have different redox potentials, which effectively ensure the stability and catalytic efficiency of nitrile hydratase.

[0027] (2) The cysteine ​​of the present invention can form a stable coordination bond with the metal center (nickel, cobalt) of MOF, and this coordination effect can stabilize the immobilization of nitrile hydratase on MOF, thereby improving the activity and stability of the enzyme; the amino and carboxyl groups on cysteine ​​can also form hydrogen bonds with MOF, thereby improving the hydrophilicity of MOF, helping to maintain the structural stability of the enzyme in water, and enhancing the catalytic activity of the enzyme; in addition, cysteine ​​can also improve the affinity between MOF and nitrile hydratase, making the immobilization of the enzyme on MOF more stable; finally, the sulfur atom of cysteine ​​can also participate in the electron transfer process, further promoting the electron transfer efficiency of the enzyme, accelerating the reaction rate, and improving the catalytic performance of nitrile hydratase.

[0028] (3) The 1-H-3,5-pyrazoledicarboxylic acid monohydrate of the present invention can form a stable chelate structure with nickel and cobalt, which can not only enhance the stability of the MOF structure, but also provide more binding sites; by regulating the pore size and morphology of MOF, the immobilization effect of nitrile hydratase can be improved, and the pore structure can provide a suitable microenvironment for nitrile hydratase, which helps to maintain the activity of nitrile hydratase.

[0029] (4) The present invention constructs a mathematical model of the stirring rate, the circulation pump flow rate and the injection angle of the injection hole. When the three satisfy the mathematical model, the optimal acrylamide production efficiency can be obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a structural schematic diagram of the reaction kettle proposed by the present invention;

[0031] Figure 2 This is a schematic diagram of the structure of the distributor proposed in the present invention.

[0032] In the figure: 1-kettle body, 2-distributor, 3-discharge pipe, 4-circulation pump, 5-circulation pipe, 6-stirring shaft, 7-first feed pipe, 8-second feed pipe, 9-stirring motor, 10-third feed pipe, 11-kettle cover, 12-stirring paddle, 13-adjusting chamber, 14-distribution chamber, 15-injection head, 16-injection hole. DETAILED DESCRIPTION

[0033] The present invention will be further explained below in conjunction with specific embodiments.

[0034] Reference Figure 1-2 The reactor proposed by the present invention comprises a reactor body 1 with an opening at the upper end, a reactor cover 11 is detachably provided at the opening at the upper end of the reactor body 1, a discharge pipe 3 is provided at the bottom of the reactor body 1, the reactor cover 11 is provided with a first feed pipe 7, a second feed pipe 8, a third feed pipe 10 and a stirring motor 9, a stirring shaft 6 is fixedly provided on the output shaft of the stirring motor 9, and the stirring shaft 6 is located in the reactor body 1 and has a plurality of stirring paddles 12 evenly distributed thereon; the first feed pipe 7, the second feed pipe 8 and the third feed pipe 10 are respectively used to add acrylonitrile, water and immobilized nitrile hydratase into the reactor.

[0035] An annular distributor 2 is also provided in the kettle body 1, and the distributor 2 includes a distribution chamber 14, and a plurality of evenly distributed adjustment chambers 13 are connected to the upper end of the distribution chamber 14. A spray head 15 is detachably provided in the adjustment chamber 13, and the spray head 15 is provided with a spray hole 16 connected to the distribution chamber 14. The distribution chamber 14 is connected to the bottom of the kettle body 1 through a circulation pipe 5, and a circulation pump 4 is provided on the circulation pipe 5.

[0036] The stirring paddles 12 are distributed above and below the distributor 2; the stirring speed N of the stirring shaft is determined according to the following formula:

[0037] N=300·Q α ·sin(θ+θ0) β

[0038] Where Q is the circulation pump flow rate; θ is the injection hole inclination angle; θ0 is the angle correction value; α is the circulation pump flow rate influence index; β is the injection hole inclination angle influence index.

[0039] For the parameters α, β and θ0 of the present application, the specific values ​​are determined through experiments. For the reactor in the embodiment of the present application, θ is 30°, Q is 3×10 -4 m 3 / min, the simulated parameters α, β, and θ0 are 0.12, 0.38, and 2.24°, respectively; the stirring rate N is determined to be 89.3 rpm by calculation. The stirring shaft speed in the reactor of Examples 1-3 of the present invention is 90 rpm.

[0040] Example 1

[0041] The method for producing acrylamide monomer solution provided by the present invention comprises the following steps: adding acrylonitrile, water and immobilized nitrile hydratase into a reaction kettle for hydration reaction to obtain acrylamide monomer;

[0042] The volume ratio of acrylonitrile to water is 1:4, and the addition amount of the immobilized nitrile hydratase is 0.1% of the total mass of acrylonitrile and water.

[0043] The hydration reaction temperature was 22°C and the time was 8h.

[0044] The method for preparing the immobilized nitrile hydratase proposed by the present invention comprises the following steps:

[0045] S1: dissolve nickel nitrate, cobalt nitrate and L-cysteine ​​in deionized water respectively;

[0046] S2: dissolving 1-H-3,5-pyrazoledicarboxylic acid monohydrate in dimethyl sulfoxide;

[0047] S3: mixing the nickel salt solution and the cobalt salt solution, adding them to the cysteine ​​solution and mixing them evenly;

[0048] S4: adding the 1-H-3,5-pyrazoledicarboxylic acid monohydrate solution of S2 to the mixed solution of S3 to react, and obtaining a catalyst support after filtering and vacuum drying;

[0049] S5: The catalyst carrier is dispersed in PBS buffer, and then nitrile hydratase is added, stirred and then allowed to stand to obtain immobilized nitrile hydratase.

[0050] The molar ratio of 1-H-3,5-pyrazoledicarboxylic acid monohydrate, nickel salt, cobalt salt and cysteine ​​is 1:0.4:0.4:0.1.

[0051] The reaction temperature in S4 is 25°C and the reaction time is 24h; the vacuum drying temperature is 35°C and the reaction time is 2h.

[0052] In S5, the stirring time is 8 h, the stirring rate is 200 rpm, the standing time is 10 h, and the standing temperature is 15°C.

[0053] Example 2

[0054] The method for producing acrylamide monomer solution provided by the present invention comprises the following steps: adding acrylonitrile, water and immobilized nitrile hydratase into a reaction kettle for hydration reaction to obtain acrylamide monomer;

[0055] The volume ratio of acrylonitrile to water is 1:3, and the added amount of the immobilized nitrile hydratase is 0.05% of the total mass of acrylonitrile and water.

[0056] The hydration reaction temperature was 18°C ​​and the time was 5 h.

[0057] The method for preparing the immobilized nitrile hydratase proposed by the present invention comprises the following steps:

[0058] S1: dissolve nickel nitrate, cobalt nitrate and L-cysteine ​​in deionized water respectively;

[0059] S2: dissolving 1-H-3,5-pyrazoledicarboxylic acid monohydrate in dimethyl sulfoxide;

[0060] S3: mixing the nickel salt solution and the cobalt salt solution, adding them to the cysteine ​​solution and mixing them evenly;

[0061] S4: adding the 1-H-3,5-pyrazoledicarboxylic acid monohydrate solution of S2 to the mixed solution of S3 to react, and obtaining a catalyst support after filtering and vacuum drying;

[0062] S5: The catalyst carrier is dispersed in PBS buffer, and then nitrile hydratase is added, stirred and then allowed to stand to obtain immobilized nitrile hydratase.

[0063] The molar ratio of 1-H-3,5-pyrazoledicarboxylic acid monohydrate, nickel nitrate, cobalt nitrate and cysteine ​​is 1:0.3:0.3:0.05.

[0064] The reaction temperature in S4 is 20°C and the reaction time is 12 h; the vacuum drying temperature is 30°C and the reaction time is 1 h.

[0065] In S5, the stirring time is 5 h, the stirring rate is 100 rpm, the standing time is 10 h, and the standing temperature is 10°C.

[0066] Example 3

[0067] The method for producing acrylamide monomer solution provided by the present invention comprises the following steps: adding acrylonitrile, water and immobilized nitrile hydratase into a reaction kettle for hydration reaction to obtain acrylamide monomer;

[0068] The volume ratio of acrylonitrile to water is 1:5, and the added amount of the immobilized nitrile hydratase is 0.15% of the total mass of acrylonitrile and water.

[0069] The hydration reaction temperature was 25°C and the time was 10 h.

[0070] The method for preparing the immobilized nitrile hydratase proposed by the present invention comprises the following steps:

[0071] S1: dissolve nickel nitrate, cobalt nitrate and L-cysteine ​​in deionized water respectively;

[0072] S2: dissolving 1-H-3,5-pyrazoledicarboxylic acid monohydrate in dimethyl sulfoxide;

[0073] S3: mixing the nickel salt solution and the cobalt salt solution, adding them to the cysteine ​​solution and mixing them evenly;

[0074] S4: adding the 1-H-3,5-pyrazoledicarboxylic acid monohydrate solution of S2 to the mixed solution of S3 to react, and obtaining a catalyst support after filtering and vacuum drying;

[0075] S5: The catalyst carrier is dispersed in PBS buffer, and then nitrile hydratase is added, stirred and then allowed to stand to obtain immobilized nitrile hydratase.

[0076] The molar ratio of 1-H-3,5-pyrazoledicarboxylic acid monohydrate, nickel nitrate, cobalt nitrate and cysteine ​​is 1:0.5:0.5:0.15.

[0077] The reaction temperature in S4 is 30°C and the reaction time is 36 h; the vacuum drying temperature is 40°C and the reaction time is 3 h.

[0078] In S5, the stirring time is 10 h, the stirring rate is 300 rpm, the standing time is 14 h, and the standing temperature is 20°C.

[0079] Comparative Example 1

[0080] The method steps for preparing the immobilized nitrile hydratase of this scheme are as follows:

[0081] S1: Dissolve nickel nitrate and L-cysteine ​​in deionized water respectively;

[0082] S2: dissolving 1-H-3,5-pyrazoledicarboxylic acid monohydrate in dimethyl sulfoxide;

[0083] S3: mixing the nickel salt solution and the cobalt salt solution, adding them to the cysteine ​​solution and mixing them evenly;

[0084] S4: adding the 1-H-3,5-pyrazoledicarboxylic acid monohydrate solution of S2 to the mixed solution of S3 to react, and obtaining a catalyst support after filtering and vacuum drying;

[0085] S5: The catalyst carrier is dispersed in PBS buffer, and then nitrile hydratase is added, stirred and then allowed to stand to obtain immobilized nitrile hydratase.

[0086] The molar ratio of 1-H-3,5-pyrazoledicarboxylic acid monohydrate, nickel nitrate and cysteine ​​is 1:0.8:0.1.

[0087] The reaction temperature in S4 is 25°C and the reaction time is 24h; the vacuum drying temperature is 35°C and the reaction time is 2h.

[0088] In S5, the stirring time is 8 h, the stirring rate is 200 rpm, the standing time is 10 h, and the standing temperature is 15°C.

[0089] Comparative Example 2

[0090] The method steps for preparing the immobilized nitrile hydratase of this scheme are as follows:

[0091] S1: Dissolve cobalt nitrate and L-cysteine ​​in deionized water respectively;

[0092] S2: dissolving 1-H-3,5-pyrazoledicarboxylic acid monohydrate in dimethyl sulfoxide;

[0093] S3: mixing the nickel salt solution and the cobalt salt solution, adding them to the cysteine ​​solution and mixing them evenly;

[0094] S4: adding the 1-H-3,5-pyrazoledicarboxylic acid monohydrate solution of S2 to the mixed solution of S3 to react, and obtaining a catalyst support after filtering and vacuum drying;

[0095] S5: The catalyst carrier is dispersed in PBS buffer, and then nitrile hydratase is added, stirred and then allowed to stand to obtain immobilized nitrile hydratase.

[0096] The molar ratio of 1-H-3,5-pyrazoledicarboxylic acid monohydrate, cobalt nitrate and cysteine ​​is 1:0.8:0.1.

[0097] The reaction temperature in S4 is 25°C and the reaction time is 24h; the vacuum drying temperature is 35°C and the reaction time is 2h.

[0098] In S5, the stirring time is 8 h, the stirring rate is 200 rpm, the standing time is 10 h, and the standing temperature is 15°C.

[0099] Comparative Example 3

[0100] The method steps for preparing the immobilized nitrile hydratase of this scheme are as follows:

[0101] S1: dissolve nickel nitrate and cobalt nitrate in deionized water respectively;

[0102] S2: dissolving 1-H-3,5-pyrazoledicarboxylic acid monohydrate in dimethyl sulfoxide;

[0103] S3: mixing the nickel nitrate solution and the cobalt nitrate solution uniformly;

[0104] S4: adding the 1-H-3,5-pyrazoledicarboxylic acid monohydrate solution of S2 to the mixed solution of S3 to react, and obtaining a catalyst support after filtering and vacuum drying;

[0105] S5: The catalyst carrier is dispersed in PBS buffer, and then nitrile hydratase is added, stirred and then allowed to stand to obtain immobilized nitrile hydratase.

[0106] The molar ratio of 1-H-3,5-pyrazoledicarboxylic acid monohydrate, nickel nitrate and cobalt nitrate is 1:0.4:0.4.

[0107] The reaction temperature in S4 is 25°C and the reaction time is 24h; the vacuum drying temperature is 35°C and the reaction time is 2h.

[0108] In S5, the stirring time is 8 h, the stirring rate is 200 rpm, the standing time is 10 h, and the standing temperature is 15°C.

[0109] Comparative Example 4

[0110] The stirring speed of the stirring paddle in this solution is 80 rpm, and the other conditions are the same as those in Example 1.

[0111] Comparative Example 5

[0112] The stirring speed of the stirring paddle in this solution is 100 rpm, and the other conditions are the same as those in Example 1.

[0113] The initial enzyme activity of the immobilized nitrile hydratase prepared in Examples 1-3 and Comparative Examples 1-3 was measured, and the test results are shown in Table 1; the acrylonitrile conversion rate of Examples 1-3 and Comparative Examples 4-5 was measured, and the test results are shown in Table 2.

[0114] Table 1 Results of immobilized nitrile hydratase activity test

[0115]

[0116]

[0117] Table 2 Acrylonitrile conversion test results

[0118] Group Acrylonitrile conversion rate (%) Example 1 99.9 Example 2 99.5 Example 3 99.8 Comparative Example 4 97.3 Comparative Example 5 97.7

[0119] It can be seen from the test results of Examples 1-3 in Table 1 that the immobilized nitrile hydratase of the present invention has a very high enzyme activity. It can be seen from the test results of Comparative Examples 1-3 that when a single metal salt is used or cysteine ​​is not added, the catalytic performance and stability of the prepared biocatalyst are greatly reduced. The reason for this phenomenon may be that Comparative Examples 1-3 cannot provide a suitable microenvironment for nitrile hydratase, nor can they optimize the active center structure of nitrile hydratase.

[0120] It can be seen from the test results in Table 2 that when the stirring rate, the circulation pump flow rate and the injection angle of the injection hole meet the mathematical model constructed in this application, the optimal acrylamide production efficiency can be achieved.

Claims

1. A method for producing an acrylamide monomer solution, characterized in that: The method comprises the following steps: adding acrylonitrile, water and immobilized nitrile hydratase into a reactor to carry out hydration reaction to obtain acrylamide monomer; The method steps for preparing the immobilized nitrile hydratase are as follows: S1: Dissolve nickel salt, cobalt salt and cysteine ​​in deionized water respectively; S2: dissolving 1-H-3,5-pyrazoledicarboxylic acid monohydrate in dimethyl sulfoxide to obtain a 1-H-3,5-pyrazoledicarboxylic acid monohydrate solution; S3: mixing the nickel salt solution and the cobalt salt solution, adding the mixture to the cysteine ​​solution and mixing them evenly to obtain a mixed solution; S4: adding the 1-H-3,5-pyrazoledicarboxylic acid monohydrate solution of S2 to the mixed solution of S3 to react, and obtaining a catalyst support after filtering and vacuum drying; S5: The catalyst carrier is dispersed in PBS buffer, and then nitrile hydratase is added, stirred and then allowed to stand to obtain immobilized nitrile hydratase.

2. The method for producing acrylamide monomer solution according to claim 1, characterized in that: The volume ratio of acrylonitrile to water is 1:3-5, and the addition amount of the immobilized nitrile hydratase is 0.05-0.15% of the total mass of acrylonitrile and water.

3. The method for producing acrylamide monomer solution according to claim 1, characterized in that: The hydration reaction temperature is 18-25°C and the time is 5-10h.

4. The method for producing acrylamide monomer solution according to claim 1, characterized in that: The nickel salt in S1 is one or more of nickel nitrate, nickel acetate, nickel sulfate, and nickel chloride; the cobalt salt is one or more of cobalt nitrate, cobalt acetate, cobalt sulfate, and cobalt chloride; and the cysteine ​​is L-cysteine.

5. The method for producing acrylamide monomer solution according to claim 1, characterized in that: The molar ratio of 1-H-3,5-pyrazoledicarboxylic acid monohydrate, nickel salt, cobalt salt and cysteine ​​is 1:0.3-0.5:0.3-0.5:0.05-0.

15.

6. The method for producing acrylamide monomer solution according to claim 1, characterized in that: The reaction temperature in S4 is 20-30°C and the reaction time is 12-36h; the vacuum drying temperature is 30-40°C and the reaction time is 1-3h.

7. The method for producing acrylamide monomer solution according to claim 1, characterized in that: In S5, the stirring time is 5-10 h, the stirring rate is 100-300 rpm, the standing time is 10-14 h, and the standing temperature is 0-35°C.

8. The method for producing acrylamide monomer solution according to claim 1, characterized in that: The reaction kettle comprises a kettle body (1) with an opening at the upper end, a kettle cover (11) is detachably provided at the opening at the upper end of the kettle body (1), a discharge pipe (3) is provided at the bottom of the kettle body (1), the kettle cover (11) is provided with a first feed pipe (7), a second feed pipe (8), a third feed pipe (10) and a stirring motor (9), a stirring shaft (6) is fixedly provided on the output shaft of the stirring motor (9), and the stirring shaft (6) is located in the kettle body (1) and has a plurality of stirring paddles (12) evenly distributed thereon; The kettle body (1) is also provided with an annular distributor (2), the distributor (2) comprising a distribution chamber (14), the upper end of the distribution chamber (14) being connected to a plurality of evenly distributed regulating chambers (13), a spray head (15) being detachably provided in the regulating chamber (13), the spray head (15) being provided with a spray hole (16) connected to the distribution chamber (14), the distribution chamber (14) being connected to the bottom of the kettle body (1) via a circulation pipe (5), and a circulation pump (4) being provided on the circulation pipe (5).

9. The method for producing acrylamide monomer solution according to claim 8, characterized in that: The stirring paddles (12) are distributed above and below the distributor (2).

10. The method for producing acrylamide monomer solution according to claim 8, characterized in that: The stirring speed N of the stirring shaft is determined by the following formula: N=300·Q α ·sin(θ+θ0) β Where Q is the circulation pump flow rate; θ is the injection hole inclination angle; θ0 is the angle correction value; α is the circulation pump flow rate influence index; β is the injection hole inclination angle influence index.

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