Molecularly imprinted material with monobasic amine adsorption function, preparation method and application thereof

Abstract

The application relates to the field of hexanediamine purification and discloses a molecular imprinting material with monamine adsorption function, a preparation method and application, which comprises the following steps: in the presence of a first dispersing agent, a monamine, an initiator and an optional carrier, a functional monomer is subjected to a polymerization reaction, and then a monamine removal operation is performed. The molecular imprinting material prepared by the application has good selective adsorption effects on hexylamine and cyclohexylideneimine, the adsorption material can be rapidly collected under an external magnetic field, and the effects of rapidly removing hexylamine and cyclohexylideneimine in a hexanediamine product are achieved.

Description

Technical Field

[0001] This invention relates to the field of hexamethylenediamine purification, specifically to a molecularly imprinted material with the function of adsorbing monoamines, its preparation method, and its application. Background Technology

[0002] Compared to other general-purpose plastics, engineering plastic Nylon 66 not only boasts high mechanical strength, good toughness and wear resistance, but also possesses excellent properties such as self-lubrication, flame retardancy, and non-toxicity, making it widely used in the machinery and electrical fields, primarily in gears, bearings, electronic appliances, and automotive parts. Hexamethylenediamine (HDME) is a key intermediate in the production of Nylon 66, and its purity and impurity composition significantly impact the product quality. The main methods for synthesizing HDME include the caprolactam method, adiponitrile method, and hexanediol method. All these methods inevitably involve distillation to purify HDME. The hexanediol method uses 1,6-hexanediol as a raw material. The process involves the amination and dehydration condensation of 1,6-hexanediol under a catalyst to obtain 1,6-hexanediamine. This process generates numerous byproducts, but these byproducts can be treated to produce 1,6-hexanediamine, thus achieving a relatively high yield.

[0003] Currently, the monoamine impurities that may be present in 1,6-hexanediamine prepared by the 1,6-hexanediamine amination process are mainly 1-hexylamine and cyclohexylamine. These impurities easily cause chain breakage in high-molecular-weight nylon fibers during the hexanediamine polymerization reaction and are strictly controlled toxic compounds in hexanediamine products. CN103936595A and CN101939286A disclose purification methods for crude hexanediamine, which employ column distillation separation, resulting in low separation efficiency and high energy consumption. Therefore, a mild method for removing the monoamines 1-hexylamine and cyclohexylamine from hexanediamine is urgently needed to meet the requirements of downstream nylon 66 production. Summary of the Invention

[0004] In view of the above situation, the present invention provides a molecularly imprinted material with the function of adsorbing monoamines, a preparation method and application. The molecularly imprinted material with the function of adsorbing monoamines (also known as a magnetic adsorbent) can specifically adsorb 1-hexylamine and cyclohexylamine in crude hexamethylenediamine, which solves the problem that the trace monoamines in crude hexamethylenediamine are difficult to remove and affect the production of nylon 66.

[0005] To achieve the above objectives, the first aspect of the present invention provides a method for preparing a molecularly imprinted material with the function of adsorbing a monoamine, the method comprising: polymerizing a functional monomer in the presence of a first dispersant, a monoamine, an initiator and an optional carrier, and then removing the monoamine.

[0006] A second aspect of the present invention provides a molecularly imprinted material with the function of adsorbing monoamines prepared by the method described above;

[0007] Alternatively, the saturation magnetization of the molecularly imprinted material is >20 emu / g.

[0008] A third aspect of the present invention provides a method for removing monoamine impurities from crude hexamethylenediamine, the method comprising: contacting the molecularly imprinted material described above with crude hexamethylenediamine;

[0009] Alternatively, the molecularly imprinted material can be prepared according to the method described above, and then the molecularly imprinted material can be contacted with crude hexamethylenediamine.

[0010] The molecularly imprinted material (magnetic molecularly imprinted material) of this invention, which has the function of adsorbing monoamines, is produced using molecular imprinting technology. Modified iron oxide microspheres are used as a carrier, and hexylamine and cyclohexylimine are used as template molecules to form core-shell magnetic microspheres with iron oxide microspheres as the core and a specifically adsorbing polymer imprinted material as the shell. The microspheres have uniform particle size and exhibit good selective adsorption of hexylamine and cyclohexylimine. Preferably, the molecularly imprinted material of this invention is rapidly collected under an external magnetic field, achieving rapid removal of hexamethylenediamine products hexylamine and cyclohexylimine. Attached Figure Description

[0011] Figure 1 The image shows a transmission electron microscope (TEM) image of the magnetic adsorbent prepared in Example 1. Detailed Implementation

[0012] The endpoints and any values ​​of the ranges 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 endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0013] The first aspect of the present invention provides a method for preparing a molecularly imprinted material with the function of adsorbing a monoamine, the method comprising: polymerizing a functional monomer in the presence of a first dispersant, a monoamine, an initiator and an optional support, and then removing the monoamine.

[0014] According to the present invention, preferably, the functional monomers include methacrylic acid and divinylbenzene.

[0015] According to the present invention, preferably, the initiator is azobisisobutyronitrile.

[0016] According to the present invention, preferably, the weight ratio of the monoamine to methacrylic acid, divinylbenzene and azobisisobutyronitrile is 1:2.5-5:10-20:0.3-0.7.

[0017] According to the present invention, preferably, the monoamine is hexylamine and / or cyclohexylamine.

[0018] According to the present invention, preferably, the weight ratio of hexylamine to cyclohexylamine is 1:0.2-5.

[0019] According to the present invention, the first dispersant is preferably at least one selected from toluene, benzene, ethylbenzene, xylene, tetrahydrofuran, and dioxane; more preferably, toluene.

[0020] According to the present invention, preferably, the amount of the first dispersant is 50-80 mL relative to each gram of monoamine.

[0021] According to the present invention, preferably, the polymerization temperature is 40-80°C, more preferably 55-65°C, and the polymerization time is 5-20h, more preferably 10-15h.

[0022] According to the present invention, preferably, the process of removing the monoamine comprises washing the reaction product with a mixture of acid and alcohol. The volume ratio of acid to alcohol in the acid-alcohol mixture can be 1:5-20. The acid in the acid-alcohol mixture can be formic acid and / or acetic acid, and the alcohol in the acid-alcohol mixture can be methanol and / or ethanol.

[0023] According to the present invention, there is no particular limitation on the number of times the reaction product is washed with a mixture of acid and alcohol, which can be determined according to the actual situation. Preferably, the number of times the reaction product is washed with a mixture of acid and alcohol is sufficient to ensure that no monoamine molecules are detected in the washing solution.

[0024] According to the present invention, preferably, the method further includes washing the product after the removal of the monoamine with a cleaning agent, wherein the cleaning agent is at least one selected from methanol, ethanol, acetonitrile, propanol and isopropanol, preferably methanol and / or ethanol.

[0025] According to the present invention, preferably, the method further includes drying the washed product; more preferably, the drying is carried out under vacuum. The vacuum drying conditions can be drying conditions commonly used in the art.

[0026] According to the present invention, preferably, the carrier is an amino-modified magnetic carrier.

[0027] According to the present invention, preferably, the amount of amino-modified magnetic carrier used is 5-10g relative to each gram of monoamine.

[0028] According to the present invention, preferably, the magnetic carrier is iron oxide microspheres, and preferably, the particle size of the iron oxide microspheres is 1-12 μm.

[0029] According to the present invention, preferably, the amino-modified magnetic support is obtained by reacting the magnetic support, the amination reagent, and the crosslinking agent in an alkaline environment for 0.5-5 hours in the presence of a second dispersant and an optional solvent.

[0030] According to the present invention, preferably, the reaction temperature during the amination process is 15-40°C.

[0031] According to the present invention, preferably, the second dispersant is a C1-C10 monohydric alcohol and / or acetonitrile, more preferably at least one selected from methanol, ethanol, acetonitrile, propanol, and isopropanol, and more preferably methanol and / or ethanol. In the present invention, "C1-C10" represents a substance with 1-10 carbon atoms.

[0032] According to the present invention, preferably, the amount of dispersant used is 15-25 mL per gram of magnetic carrier.

[0033] According to the present invention, preferably, the amination agent is an amino-containing silanizing agent, preferably (3-aminopropyl)triethoxysilane and / or (3-aminopropyl)trimethoxysilane;

[0034] According to the present invention, preferably, the amount of amination reagent used is 0.2-1 mL relative to each gram of magnetic carrier.

[0035] According to the present invention, preferably, the crosslinking agent is a silanizing agent, preferably tetramethoxysilane and / or tetraethoxysilane.

[0036] According to the present invention, preferably, the volume ratio of the amination agent to the crosslinking agent is 1:0.5-2.

[0037] According to the present invention, preferably, the amination reagent and the crosslinking agent are added in the form of an alcohol solution, that is, an alcohol solution containing the amination reagent and the crosslinking agent is first prepared by mixing alcohol with the amination reagent and the crosslinking agent. The amount of alcohol used is 5-15 mL relative to each mL of the amination reagent. The alcohol in the alcohol solution containing the amination reagent and the crosslinking agent is methanol and / or ethanol.

[0038] According to the present invention, the alkaline environment can be provided by ammonia water, preferably, the concentration of ammonia water is 20-30 wt%, and more preferably, the amount of ammonia water used is 0.5-1.5 mL relative to each gram of magnetic carrier.

[0039] According to the present invention, preferably, the solvent is water; more preferably, the amount of solvent used is 0.5-1.5 mL per gram of magnetic carrier.

[0040] According to the present invention, preferably, the method of obtaining the amino-modified magnetic support further includes washing and drying the reaction product. More preferably, the washing agent used in the washing process includes at least one selected from methanol, ethanol, acetonitrile, propanol, and isopropanol, and more preferably methanol and / or ethanol. More preferably, the drying is carried out under vacuum, and the vacuum drying conditions can be drying conditions commonly used in the art.

[0041] A second aspect of the present invention provides a molecularly imprinted material with the function of adsorbing monoamines prepared by the method described above;

[0042] Alternatively, the saturation magnetization of the molecularly imprinted material is >20 emu / g. Molecularly imprinted materials exhibit excellent superparamagnetism, enabling rapid separation.

[0043] According to the present invention, preferably, the particle size of the molecularly imprinted material is 1-50 μm.

[0044] A third aspect of the present invention provides a method for removing monoamine impurities from crude hexamethylenediamine, the method comprising: contacting the molecularly imprinted material described above with crude hexamethylenediamine;

[0045] Alternatively, the molecularly imprinted material can be prepared according to the method described above, and then the molecularly imprinted material can be contacted with crude hexamethylenediamine.

[0046] In this invention, it is understood that the crude hexamethylenediamine is the hexamethylenediamine before it is treated by the method of this invention, that is, the hexamethylenediamine before purification.

[0047] According to the present invention, the source of crude hexamethylenediamine is not particularly limited. Preferably, the crude hexamethylenediamine is hexamethylenediamine after distillation. More preferably, the purity of the crude hexamethylenediamine is >99.5%, the content of hexamethylenediamine in the crude hexamethylenediamine is <0.5wt%, and the content of cyclohexamethylenediamine in the crude hexamethylenediamine is <0.5wt%.

[0048] According to the present invention, preferably, the contact conditions include a temperature of 40-60°C and a time of 10-30 hours.

[0049] According to the present invention, preferably, the mass ratio of the molecularly imprinted material to crude hexamethylenediamine is 1:500-2000, more preferably 1:500-600.

[0050] In this invention, the method for removing monoamine impurities from crude hexamethylenediamine further includes regenerating the molecularly imprinted material after contact with crude hexamethylenediamine. The regeneration process can be carried out by any method known to those skilled in the art that can be used for adsorbent regeneration. Preferably, the regeneration method includes any one of solvent washing, Soxhlet extraction, gas purging, solid-phase extraction, and supercritical extraction.

[0051] The molecularly imprinted material (magnetic molecularly imprinted material) of the present invention with the function of adsorbing monoamines is a core-shell structure magnetic microsphere with magnetic iron oxide microspheres as the core and a polymer imprinted shell layer covering the core. The polymer imprinted shell layer contains hexylamine and cyclohexylimine molecular imprints.

[0052] The present invention will be described in detail below through embodiments. In the following embodiments,

[0053] The room temperature is approximately 25°C.

[0054] Example 1

[0055] (1) Take 1g of iron oxide microspheres (with a particle size of about 10μm) and add 20mL of methanol, 1mL of water and 1mL of 25wt% concentrated ammonia. After ultrasonic mixing, add an ethanol solution containing (3-aminopropyl)triethoxysilane and tetraethoxysilane (0.5mL of (3-aminopropyl)triethoxysilane, 0.5mL of tetraethoxysilane and 8mL of ethanol). Stir the reaction at room temperature for 1h. Then, use a magnet to separate the product magnetically, wash the product with methanol and dry it under vacuum to obtain the surface amino-modified iron oxide microspheres.

[0056] (2) Dissolve 0.5g hexylamine, 0.5g cyclohexylamine, 3g methacrylic acid, 15g divinylbenzene, and 0.5g azobisisobutyronitrile in 60mL of toluene. After mixing, add 6g of amino-modified iron oxide magnetic microspheres, mix well, and purge with nitrogen for 5min. Seal the mixture and react at 60℃ for 12h. After the reaction is complete, dry the solid and wash it with a mixture of methanol and formic acid at a volume ratio of 1:9 until hexylamine and cyclohexylamine are no longer detected in the washing solution. Then, vacuum dry to obtain the magnetic adsorbent (a molecularly imprinted material with the function of adsorbing monoamines).

[0057] The above magnetic adsorbents (such as...) were investigated using transmission electron microscopy (TEM). Figure 1 As shown), by Figure 1 It can be seen that the particle size of the modified imprinted material is significantly increased, indicating that the molecularly imprinted polymer has been significantly modified onto the surface of the iron oxide microspheres.

[0058] According to VSM hysteresis loop testing, the saturation magnetization of the magnetic adsorbent is >20 emu / g, meaning that the magnetic adsorbent still exhibits good superparamagnetism and can be separated rapidly.

[0059] Example 2

[0060] (1) Take 1g of iron oxide microspheres (with a particle size of about 5μm) and add 20mL of ethanol, 0.8mL of water and 0.8mL of 25wt% concentrated ammonia. After ultrasonic mixing, add an ethanol solution containing (3-aminopropyl)triethoxysilane and tetraethoxysilane (0.6mL of (3-aminopropyl)triethoxysilane, 0.4mL of tetraethoxysilane and 10mL of ethanol). Stir the reaction at room temperature for 1h. Then, use a magnet to separate the product magnetically, wash the product with methanol, and dry it under vacuum to obtain the surface amino-modified iron oxide microspheres.

[0061] (2) Dissolve 0.5g hexylamine, 0.5g cyclohexylamine, 4g methacrylic acid, 16g divinylbenzene, and 0.8g azobisisobutyronitrile in 80mL of toluene. After mixing, add 7g of amino-modified iron oxide magnetic microspheres, mix well, and purge with nitrogen for 5min. Seal the mixture and react at 65℃ for 15h. After the reaction is complete, dry the solid and wash it with a mixture of methanol and formic acid at a volume ratio of 1:10 until hexylamine and cyclohexylamine are no longer detected in the washing solution. Then, vacuum dry to obtain the magnetic adsorbent.

[0062] Example 3

[0063] (1) Take 1g of iron oxide microspheres (with a particle size of about 8μm) and add 15mL of methanol, 0.8mL of water and 1.2mL of 25wt% concentrated ammonia. After ultrasonic mixing, add an ethanol solution containing (3-aminopropyl)triethoxysilane and tetraethoxysilane (0.8mL of (3-aminopropyl)triethoxysilane, 0.6mL of tetraethoxysilane and 10mL of ethanol). Stir the reaction at room temperature for 1h. Then, use a magnet to separate the product magnetically, wash the product with methanol and dry it under vacuum to obtain the surface amino-modified iron oxide microspheres.

[0064] (2) Dissolve 0.5g hexylamine, 0.5g cyclohexylamine, 2g methacrylic acid, 14g divinylbenzene, and 0.6g azobisisobutyronitrile in 60mL of toluene. After mixing, add 8g of amino-modified iron oxide magnetic microspheres, mix well, and purge with nitrogen for 5min. Seal the mixture and react at 60℃ for 15h. After the reaction is complete, dry the solid and wash it with a mixture of ethanol and acetic acid in a volume ratio of 1:9 until hexylamine and cyclohexylamine are no longer detected in the washing solution. Then, vacuum dry to obtain the magnetic adsorbent.

[0065] Example 4

[0066] The magnetic adsorbent was prepared according to the method of Example 1, except that the iron oxide microspheres were not subjected to the surface amination modification in step (1), and 6g of iron oxide magnetic microspheres were directly added in step 2.

[0067] TEM characterization revealed that the surface of the microspheres was almost entirely free of molecularly imprinted material coating.

[0068] Example 5

[0069] The magnetic adsorbent was prepared according to the method in Example 1, except that the amount of methacrylic acid used was 13g and the amount of divinylbenzene used was 5g.

[0070] Example 6

[0071] The magnetic adsorbent was prepared according to the method of Example 1, except that methacrylic acid was replaced with an equal weight of 2-ethylacrylic acid.

[0072] Comparative Example 1

[0073] The magnetic adsorbent was prepared according to the method in Example 1, except that hexylamine and cyclohexylamine were not added.

[0074] Test case

[0075] The magnetic adsorbents prepared in the above examples and comparative examples were used to purify crude hexamethylenediamine (hexamethylenediamine after distillation) to obtain purified hexamethylenediamine product. The purification method included adding 0.1 kg of magnetic adsorbent to 50 kg of hexamethylenediamine, stirring and adsorbing at 50 °C for 20 h, and then separating the magnetic adsorbent using a strong magnet. The purified hexamethylenediamine was then subjected to gas chromatography to test its purity and the contents of hexamethylenediamine and cyclohexamethylenediamine. The results are shown in Table 1.

[0076] Recovery rate of hexamethylenediamine = (Mass of purified hexamethylenediamine ÷ Mass of hexamethylenediamine before purification) × 100%

[0077] Table 1

[0078]

[0079] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for preparing a molecularly imprinted material with the function of adsorbing monoamines, characterized in that, The method includes: polymerizing a functional monomer in an inert atmosphere in the presence of a first dispersant, a monoamine, an initiator, and a support, followed by removing the monoamine. The functional monomers include methacrylic acid and divinylbenzene; The carrier is an amino-modified magnetic carrier, and the magnetic carrier is iron oxide microspheres.

2. The method according to claim 1, wherein, The initiator is azobisisobutyronitrile.

3. The method according to claim 2, wherein, The monoamine is hexylamine and / or cyclohexylamine; And / or, the weight ratio of the monoamine to methacrylic acid, divinylbenzene, and azobisisobutyronitrile is 1: 2.5-5：10-20：0.3-0.7。 4. The method according to claim 1, wherein, The first dispersant is at least one selected from toluene, benzene, ethylbenzene, xylene, tetrahydrofuran, and dioxane; And / or, the amount of the first dispersant is 50-80 mL relative to each gram of monoamine.

5. The method according to claim 1, wherein, The polymerization reaction is carried out at a temperature of 40-80℃ for 5-20 hours. And / or, the process of removing monoamines includes washing the product of the polymerization reaction with a mixture of acid and alcohol.

6. The method according to claim 1, wherein, The amount of the amino-modified magnetic carrier used is 5-10g relative to each gram of monoamine.

7. The method according to claim 1 or 6, wherein, The amino-modified magnetic carrier is obtained by reacting the magnetic carrier, the amination reagent, and the crosslinking agent in an alkaline environment for 0.5-5 hours in the presence of a second dispersant and an optional solvent.

8. The method according to claim 7, wherein, The second dispersant is a C1-C10 monohydric alcohol and / or acetonitrile; the amount of the second dispersant is 15-25 mL per gram of magnetic carrier. And / or, the amination reagent is an amino-containing silanizing reagent; the amount of the amination reagent used is 0.2-1 mL relative to each gram of magnetic carrier; And / or, the crosslinking agent is a silanizing agent; And / or, the volume ratio of the amination agent to the crosslinking agent is 1:0.5-2.

9. The method according to claim 8, wherein, The amination reagent is (3-aminopropyl)triethoxysilane and / or (3-aminopropyl)trimethoxysilane; the amount of the amination reagent used is 0.2-1 mL per gram of magnetic carrier; And / or, the crosslinking agent is tetramethoxysilane and / or tetraethoxysilane.

10. Molecularly imprinted materials prepared by the method according to any one of claims 1-9.

11. The molecularly imprinted material according to claim 10, wherein, The saturation magnetization of the molecularly imprinted material is >20 emu / g.

12. A method for removing monoamine impurities from crude hexamethylenediamine, characterized in that, The method includes: contacting the molecularly imprinted material of claim 10 or 11 with crude hexamethylenediamine; Alternatively, the molecularly imprinted material may be prepared according to the method described in any one of claims 1-9, and then the molecularly imprinted material may be contacted with crude hexamethylenediamine.

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