A MOFs-supported quaternary ammonium base catalyst for the synthesis of acryloyloxyethyltrimethylammonium chloride and a preparation method thereof

Abstract

The present invention relates to the field of catalyst processing technology, and specifically discloses a MOFs-supported quaternary ammonium base catalyst for use in the synthesis of acryloyloxyethyltrimethylammonium chloride and a preparation method thereof. The preparation method comprises: first preparing UiO-66-AZO from 4,4'-azodibenzoic acid and ZrCl4, then activating and grafting a quaternary ammonium salt to obtain a catalyst precursor, and finally mixing and loading homemade CoFe2O4 nanoparticles, a catalyst precursor, and a dispersant in ethanol. The high specific surface area of ​​UiO-66-AZO in the catalyst provides abundant active sites, the quaternary ammonium base group enhances the alkaline catalytic ability, and CoFe2O4 imparts magnetic separation characteristics. In the synthesis of acryloyloxyethyltrimethylammonium chloride, the catalyst exhibits high activity, excellent cyclic stability, and high selectivity, while avoiding the difficulty of separating homogeneous catalysts, meeting the requirements of green chemistry.

Description

Technical Field

[0001] The present invention relates to the technical field of catalysts, and more particularly to an MOFs-supported quaternary ammonium base catalyst used in the synthesis of acryloyloxyethyltrimethylammonium chloride and a preparation method thereof. Background Art

[0002] Acryloyloxyethyltrimethylammonium chloride is an important cationic monomer widely used in flocculants and polymer material modification in fields such as water treatment, papermaking, and textiles. Its synthesis typically involves a quaternization reaction, which requires the presence of an alkaline catalyst. Conventional processes employ homogeneous quaternary ammonium bases as catalysts, but these processes present challenges such as difficult catalyst separation, low recycling rates, complex product purification, and environmental pollution. Therefore, the development of efficient and recyclable supported quaternary ammonium base catalysts has become a research hotspot in this field.

[0003] Metal-organic frameworks (MOFs) have shown great potential as catalyst supports due to their high specific surface area, good thermal stability, and tunable pore structure. In particular, when MOFs are used as supports, different active sites can be introduced through surface functionalization, thereby achieving effective catalysis of specific reactions. In the prior art, alkalinity can be enhanced by introducing quaternary ammonium groups into MOFs, but the loading efficiency of quaternary ammonium bases and the adaptability of MOFs pores have not been systematically optimized, which can easily lead to the loss of active components. In addition, the recycling of the catalyst still relies on centrifugation or filtration, making it difficult to achieve industrial continuous operation. Based on this, the present invention provides a MOFs-supported quaternary ammonium base catalyst for the synthesis of acryloyloxyethyltrimethylammonium chloride and a preparation method thereof to solve the above-mentioned technical problems. Summary of the Invention

[0004] The present invention provides a MOFs-supported quaternary ammonium base catalyst for use in the synthesis of acryloyloxyethyltrimethylammonium chloride and a preparation method thereof. The catalyst prepared by the present invention exhibits high activity, excellent cyclic stability, and high selectivity in the synthesis of acryloyloxyethyltrimethylammonium chloride, while avoiding the difficulty of separating homogeneous catalysts and meeting the requirements of green chemistry.

[0005] In a first aspect, the present invention provides a method for preparing a MOFs-supported quaternary ammonium base catalyst for the synthesis of acryloyloxyethyltrimethylammonium chloride, using the following technical solution:

[0006] A method for preparing a MOFs-supported quaternary ammonium base catalyst for the synthesis of acryloyloxyethyltrimethylammonium chloride comprises the following steps:

[0007] S1. Dissolve 4,4'-azodibenzoic acid and ZrCl4 in N,N-dimethylformamide, add 35-40wt% hydrochloric acid, stir continuously at 118-125°C for 20-25h, then centrifuge, wash and dry to obtain a MOF framework intermediate, labeled as UiO-66-AZO;

[0008] S2. Disperse UiO-66-AZO in N,N-dimethylformamide, add an activator, and continue stirring at room temperature for 1-3 hours. Then, add N,N,N-trimethyl-1-dodecylammonium bromide, continue stirring at 58-65°C for 20-25 hours, and then centrifuge, wash, and dry to obtain a catalyst precursor.

[0009] S3, dissolving CoCl2•6H2O and FeCl3•6H2O in deionized water, adding ammonia water dropwise under nitrogen protection to adjust the pH, then heating to 130-140°C, stirring continuously for 3-6 hours, and then separating, washing, and drying to obtain CoFe2O4 nanoparticles;

[0010] S4. Disperse CoFe2O4 nanoparticles in ethanol, add a catalyst precursor and a dispersant, and continue stirring at 60-70°C for 2-4 hours, then separate, wash, and dry to obtain a MOFs-supported quaternary ammonium base catalyst.

[0011] Preferably, in step S1, the mass ratio of 4,4'-azodibenzoic acid, ZrCl4, N,N-dimethylformamide and hydrochloric acid is 1:(0.8-1.3):(5-10):(0.08-0.6).

[0012] Preferably, the activating agent in step S2 is composed of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide in a molar ratio of 1:(1-3).

[0013] Preferably, in step S2, the mass ratio of UiO-66-AZO, N,N-dimethylformamide, activator and N,N,N-trimethyl-1-dodecylammonium bromide is 1:(8-12):(0.8-1.5):(2-4).

[0014] Preferably, the pH in step S3 is adjusted to 9-11.

[0015] Preferably, in step S3, the mass ratio of CoCl2•6H2O to FeCl3•6H2O is 1:(2.3-2.8).

[0016] Preferably, the dispersant in step S4 is at least one of polyethylene glycol, sodium dodecylbenzenesulfonate and oleic acid.

[0017] Preferably, in step S4, the components by weight include 1-3 parts of CoFe2O4 nanoparticles, 15-20 parts of ethanol, 2-6 parts of catalyst precursor and 0.3-0.5 parts of dispersant.

[0018] In a second aspect, the present invention further provides a MOFs-supported quaternary ammonium base catalyst for the synthesis of acryloyloxyethyltrimethylammonium chloride, which adopts the following technical solution:

[0019] A MOFs-supported quaternary ammonium base catalyst used for the synthesis of acryloyloxyethyltrimethylammonium chloride is prepared by the above-mentioned preparation method.

[0020] In summary, the present invention has the following beneficial effects:

[0021] This invention prepares a catalyst using a UiO-66-AZO metal-organic framework (MOF) as a carrier, covalently grafted with quaternary ammonium base active sites, and composited with magnetic CoFe2O4 nanoparticles. The UiO-66-AZO carrier, with 4,4'-azodibenzoic acid as a ligand, forms a porous framework with high specific surface area with ZrCl4 under solvothermal conditions. Its azo groups not only enhance electron transfer but also provide anchoring sites for subsequent quaternary ammonium base grafting. The quaternary ammonium base active sites are covalently immobilized on the MOF surface via an EDC / NHS system via amide bonds, forming a high-density alkaline site. This significantly improves the conversion rate and selectivity of acryloyloxyethyltrimethylammonium chloride synthesis while preventing the loss of active components due to physical adsorption. The CoFe2O4 magnetic particles are synthesized via a coprecipitation-hydrothermal method. Their spinel structure imparts strong magnetism. Combined with a dispersant, the interfacial composite is stabilized by hydrogen bonds and steric hindrance, allowing the catalyst to be rapidly separated by an external magnetic field, preventing the magnetic particles from falling off and optimizing the distribution of active sites.

[0022] In summary, the catalyst prepared by this invention not only achieves efficient catalysis through the porosity of MOFs and the strong basicity of quaternary ammonium bases, but also utilizes a magnetic core to simplify the separation process. Combined with covalent grafting and interfacial stabilization, this catalyst overcomes the challenges of traditional catalysts, such as the easy loss of active sites and high energy consumption for recovery. In the synthesis of acryloyloxyethyltrimethylammonium chloride, its high activity, high selectivity, and magnetic recyclability significantly reduce production costs and environmental pollution, providing a solution for the industrial application of green chemical processes. DETAILED DESCRIPTION

[0023] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0024] The experimental methods in the following examples are conventional methods unless otherwise specified, and the experimental materials used are purchased from conventional biochemical reagent stores unless otherwise specified. The quantitative experiments in the following examples were all repeated three times, and the data are the average or mean ± standard deviation of the three repeated experiments.

[0025] Polyethylene glycol, purchased from Liaoning Kelong Fine Chemical Co., Ltd., CAS25322-68-3;

[0026] Oleic acid was purchased from Hebei Clavier Biotechnology Co., Ltd., product number 112-80-1.

[0027] Example 1

[0028] A method for preparing a MOFs-supported quaternary ammonium base catalyst for the synthesis of acryloyloxyethyltrimethylammonium chloride comprises the following steps:

[0029] S1. Add 4,4'-azodibenzoic acid, ZrCl4, and N,N-dimethylformamide to a reactor, add 35 wt% hydrochloric acid, control the stirring rate to 200 rpm, and continue stirring at 118 ° C for 25 hours. After centrifugation, washing, and drying, a MOF framework intermediate is obtained, labeled as UiO-66-AZO, wherein the mass ratio of 4,4'-azodibenzoic acid, ZrCl4, N,N-dimethylformamide, and hydrochloric acid is 1:0.8:5:0.08;

[0030] S2. Dispersing UiO-66-AZO in N,N-dimethylformamide, adding an activator, stirring continuously for 3 hours at room temperature, and then adding N,N,N-trimethyl-1-dodecylammonium bromide. The stirring rate is controlled to 200 rpm, and the mixture is stirred continuously for 25 hours at 58° C., followed by centrifugal washing and drying to obtain a catalyst precursor, wherein the activator is composed of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide in a molar ratio of 1:1, and the mass ratio of UiO-66-AZO, N,N-dimethylformamide, activator and N,N,N-trimethyl-1-dodecylammonium bromide is 1:8:0.8:2;

[0031] S3, dissolving CoCl2•6H2O and FeCl3•6H2O in deionized water in a mass ratio of 1:2.3:7, adding ammonia water dropwise under nitrogen protection to adjust the pH to 9, heating to 130°C, stirring continuously for 6 hours, and then separating, washing, and drying to obtain CoFe2O4 nanoparticles;

[0032] S4. Disperse 1 part of CoFe2O4 nanoparticles in 15 parts of ethanol by weight, add 2 parts of catalyst precursor and 0.3 parts of oleic acid, control the stirring rate to 200 rpm, continue stirring at 60°C for 4 hours, then separate, wash and dry to obtain a MOFs-supported quaternary ammonium base catalyst.

[0033] Example 2

[0034] A method for preparing a MOFs-supported quaternary ammonium base catalyst for the synthesis of acryloyloxyethyltrimethylammonium chloride comprises the following steps:

[0035] S1. Add 4,4'-azodibenzoic acid, ZrCl4, and N,N-dimethylformamide to a reactor, add 36 wt% hydrochloric acid, control the stirring rate to 220 rpm, and continue stirring at 120 ° C for 24 hours. After centrifugation, washing, and drying, a MOF framework intermediate is obtained, which is labeled as UiO-66-AZO. The mass ratio of 4,4'-azodibenzoic acid, ZrCl4, N,N-dimethylformamide, and hydrochloric acid is 1:1.1:7:0.3.

[0036] S2. Dispersing UiO-66-AZO in N,N-dimethylformamide, adding an activator, stirring continuously for 2 hours at room temperature, and then adding N,N,N-trimethyl-1-dodecylammonium bromide. The stirring rate is controlled to 220 rpm, and stirring is continued for 24 hours at 60°C. After centrifugation, washing and drying, a catalyst precursor is obtained, wherein the activator is composed of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide in a molar ratio of 1:2, and the mass ratio of UiO-66-AZO, N,N-dimethylformamide, activator and N,N,N-trimethyl-1-dodecylammonium bromide is 1:9:1.2:3;

[0037] S3, dissolving CoCl2•6H2O and FeCl3•6H2O in deionized water in a mass ratio of 1:2.4:8, adding ammonia water dropwise under nitrogen protection to adjust the pH to 10, heating to 135°C, stirring continuously for 5 h, and then separating, washing, and drying to obtain CoFe2O4 nanoparticles;

[0038] S4. Disperse 2 parts of CoFe2O4 nanoparticles in 16 parts of ethanol by weight, add 4 parts of catalyst precursor and 0.4 parts of sodium dodecylbenzenesulfonate, control the stirring rate to 300 rpm, continue stirring at 63°C for 3.8 hours, then separate, wash and dry to obtain a MOFs-supported quaternary ammonium base catalyst.

[0039] Example 3

[0040] A method for preparing a MOFs-supported quaternary ammonium base catalyst for the synthesis of acryloyloxyethyltrimethylammonium chloride comprises the following steps:

[0041] S1. Add 4,4'-azodibenzoic acid, ZrCl4, and N,N-dimethylformamide to a reactor, add 40 wt% hydrochloric acid, control the stirring rate to 400 rpm, and continue stirring at 125°C for 20 hours. After centrifugation, washing, and drying, a MOF framework intermediate is obtained, which is labeled as UiO-66-AZO. The mass ratio of 4,4'-azodibenzoic acid, ZrCl4, N,N-dimethylformamide, and hydrochloric acid is 1:1.3:10:0.6.

[0042] S2. Dispersing UiO-66-AZO in N,N-dimethylformamide, adding an activator, stirring continuously for 3 hours at room temperature, and then adding N,N,N-trimethyl-1-dodecylammonium bromide. The stirring rate is controlled to 400 rpm, and the mixture is stirred continuously for 20 hours at 65°C, followed by centrifugal washing and drying to obtain a catalyst precursor, wherein the activator is composed of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide in a molar ratio of 1:3, and the mass ratio of UiO-66-AZO, N,N-dimethylformamide, activator and N,N,N-trimethyl-1-dodecylammonium bromide is 1:12:1.5:4;

[0043] S3, dissolving CoCl2•6H2O and FeCl3•6H2O in deionized water at a mass ratio of 1:2.8:10, adding ammonia water dropwise under nitrogen protection to adjust the pH to 11, heating to 140°C, stirring continuously for 3 h, and then separating, washing, and drying to obtain CoFe2O4 nanoparticles;

[0044] S4. Disperse 3 parts of CoFe2O4 nanoparticles in 20 parts of ethanol by weight, add 6 parts of catalyst precursor and 0.5 parts of polyethylene glycol, control the stirring rate to 400 rpm, continue stirring at 60°C for 2 hours, then separate, wash and dry to obtain a MOFs-supported quaternary ammonium base catalyst.

[0045] Example 4

[0046] A method for preparing a MOFs-supported quaternary ammonium base catalyst for the synthesis of acryloyloxyethyltrimethylammonium chloride comprises the following steps:

[0047] S1. Add 4,4'-azodibenzoic acid, ZrCl4, and N,N-dimethylformamide to a reactor, add 38 wt% hydrochloric acid, control the stirring rate to 400 rpm, and continue stirring at 125°C for 24 hours. After that, centrifuge, wash, and dry to obtain a MOF framework intermediate, labeled as UiO-66-AZO, wherein the mass ratio of 4,4'-azodibenzoic acid, ZrCl4, N,N-dimethylformamide, and hydrochloric acid is 1:1.2:10:0.5;

[0048] S2. Dispersing UiO-66-AZO in N,N-dimethylformamide, adding an activator, stirring continuously for 2.5 hours at room temperature, and then adding N,N,N-trimethyl-1-dodecylammonium bromide. The stirring rate is controlled to 400 rpm, and the mixture is stirred continuously for 24 hours at 60°C, followed by centrifugal washing and drying to obtain a catalyst precursor, wherein the activator is composed of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide in a molar ratio of 1:3, and the mass ratio of UiO-66-AZO, N,N-dimethylformamide, activator and N,N,N-trimethyl-1-dodecylammonium bromide is 1:10:1.4:4;

[0049] S3, dissolving CoCl2•6H2O and FeCl3•6H2O in deionized water in a mass ratio of 1:2.8:10, adding ammonia water dropwise under nitrogen protection to adjust the pH to 10, heating to 140°C, stirring continuously for 4 hours, and then separating, washing, and drying to obtain CoFe2O4 nanoparticles;

[0050] S4. Disperse 3 parts of CoFe2O4 nanoparticles in 18 parts of ethanol by weight, add 6 parts of catalyst precursor and 0.5 parts of sodium dodecylbenzenesulfonate, control the stirring rate to 400 rpm, continue stirring at 70°C for 3 hours, then separate, wash and dry to obtain a MOFs-supported quaternary ammonium base catalyst.

[0051] Comparative Example 1

[0052] A method for preparing a MOFs-supported quaternary ammonium base catalyst for the synthesis of acryloyloxyethyltrimethylammonium chloride comprises the following steps:

[0053] S1. Add 4,4'-azodibenzoic acid, ZrCl4, and N,N-dimethylformamide to a reactor, add 38 wt% hydrochloric acid, control the stirring rate to 400 rpm, and continue stirring at 125°C for 24 hours. After that, centrifuge, wash, and dry to obtain a MOF framework intermediate, labeled as UiO-66-AZO, wherein the mass ratio of 4,4'-azodibenzoic acid, ZrCl4, N,N-dimethylformamide, and hydrochloric acid is 1:1.2:10:0.5;

[0054] S2. Dispersing UiO-66-AZO in N,N-dimethylformamide, adding an activator, stirring continuously for 2.5 hours at room temperature, and then adding N,N,N-trimethyl-1-dodecyl ammonium bromide. The stirring rate is controlled to 400 rpm, and the mixture is stirred continuously for 24 hours at 60°C, followed by centrifugal washing and drying. The result is a MOFs-supported quaternary ammonium base catalyst, wherein the activator is composed of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide in a molar ratio of 1:3, and the mass ratio of UiO-66-AZO, N,N-dimethylformamide, activator and N,N,N-trimethyl-1-dodecyl ammonium bromide is 1:10:1.4:4;

[0055] Comparative Example 2

[0056] A method for preparing a MOFs-supported quaternary ammonium base catalyst for the synthesis of acryloyloxyethyltrimethylammonium chloride comprises the following steps:

[0057] S1. Add 4,4'-azodibenzoic acid, ZrCl4, and N,N-dimethylformamide to a reactor, add 38 wt% hydrochloric acid, control the stirring rate to 400 rpm, and continue stirring at 125°C for 24 hours. After that, centrifuge, wash, and dry to obtain a MOF framework intermediate, labeled as UiO-66-AZO, wherein the mass ratio of 4,4'-azodibenzoic acid, ZrCl4, N,N-dimethylformamide, and hydrochloric acid is 1:1.2:10:0.5;

[0058] S2. Dispersing UiO-66-AZO in N,N-dimethylformamide, adding N,N,N-trimethyl-1-dodecylammonium bromide, controlling the stirring rate to 400 rpm, stirring continuously at 60° C. for 24 h, and then centrifuging, washing, and drying to obtain a catalyst precursor, wherein the mass ratio of UiO-66-AZO, N,N-dimethylformamide, and N,N,N-trimethyl-1-dodecylammonium bromide is 1:10:4;

[0059] S3, dissolving CoCl2•6H2O and FeCl3•6H2O in deionized water in a mass ratio of 1:2.8:10, adding ammonia water dropwise under nitrogen protection to adjust the pH to 10, heating to 140°C, stirring continuously for 4 hours, and then separating, washing, and drying to obtain CoFe2O4 nanoparticles;

[0060] S4. Disperse 3 parts of CoFe2O4 nanoparticles in 18 parts of ethanol by weight, add 6 parts of catalyst precursor and 0.5 parts of sodium dodecylbenzenesulfonate, control the stirring rate to 400 rpm, continue stirring at 70°C for 3 hours, then separate, wash and dry to obtain a MOFs-supported quaternary ammonium base catalyst.

[0061] Comparative Example 3

[0062] A method for preparing a MOFs-supported quaternary ammonium base catalyst for the synthesis of acryloyloxyethyltrimethylammonium chloride comprises the following steps:

[0063] S1. Add 4,4'-azodibenzoic acid, ZrCl4, and N,N-dimethylformamide to a reactor, add 38 wt% hydrochloric acid, control the stirring rate to 400 rpm, and continue stirring at 125°C for 24 hours. After that, centrifuge, wash, and dry to obtain a MOF framework intermediate, labeled as UiO-66-AZO, wherein the mass ratio of 4,4'-azodibenzoic acid, ZrCl4, N,N-dimethylformamide, and hydrochloric acid is 1:1.2:10:0.5;

[0064] S2. Dispersing UiO-66-AZO in N,N-dimethylformamide, adding an activator, stirring continuously for 2.5 hours at room temperature, and then adding N,N,N-trimethyl-1-dodecylammonium bromide. The stirring rate is controlled to 400 rpm, and the mixture is stirred continuously for 24 hours at 60°C, followed by centrifugal washing and drying to obtain a catalyst precursor, wherein the activator is composed of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide in a molar ratio of 1:3, and the mass ratio of UiO-66-AZO, N,N-dimethylformamide, activator and N,N,N-trimethyl-1-dodecylammonium bromide is 1:10:1.4:4;

[0065] S3. Disperse 3 parts of Fe3O4 nanoparticles in 18 parts of ethanol by weight, add 6 parts of catalyst precursor and 0.5 parts of sodium dodecylbenzenesulfonate, control the stirring rate to 400 rpm, continue stirring at 70°C for 3 hours, then separate, wash and dry to obtain a MOFs-supported quaternary ammonium base catalyst.

[0066] Comparative Example 4

[0067] A method for preparing a MOFs-supported quaternary ammonium base catalyst for the synthesis of acryloyloxyethyltrimethylammonium chloride comprises the following steps:

[0068] S1. Add 4,4'-azodibenzoic acid, ZrCl4, and N,N-dimethylformamide to a reactor, add 38 wt% hydrochloric acid, control the stirring rate to 400 rpm, and continue stirring at 125°C for 24 hours. After that, centrifuge, wash, and dry to obtain a MOF framework intermediate, labeled as UiO-66-AZO, wherein the mass ratio of 4,4'-azodibenzoic acid, ZrCl4, N,N-dimethylformamide, and hydrochloric acid is 1:1.2:10:0.5;

[0069] S2. Dispersing UiO-66-AZO in N,N-dimethylformamide, adding an activator, stirring continuously for 2.5 hours at room temperature, then adding tetramethylammonium bromide, controlling the stirring rate to 400 rpm, stirring continuously for 24 hours at 60°C, centrifuging, washing, and drying to obtain a catalyst precursor, wherein the activator is composed of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide in a molar ratio of 1:3, and the mass ratio of UiO-66-AZO, N,N-dimethylformamide, activator, and tetramethylammonium bromide is 1:10:1.4:4;

[0070] S3, dissolving CoCl2•6H2O and FeCl3•6H2O in deionized water in a mass ratio of 1:2.8:10, adding ammonia water dropwise under nitrogen protection to adjust the pH to 10, heating to 140°C, stirring continuously for 4 hours, and then separating, washing, and drying to obtain CoFe2O4 nanoparticles;

[0071] S4. Disperse 3 parts of CoFe2O4 nanoparticles in 18 parts of ethanol by weight, add 6 parts of catalyst precursor and 0.5 parts of sodium dodecylbenzenesulfonate, control the stirring rate to 400 rpm, continue stirring at 70°C for 3 hours, then separate, wash and dry to obtain a MOFs-supported quaternary ammonium base catalyst.

[0072] Comparative Example 5

[0073] A method for preparing a MOFs-supported quaternary ammonium base catalyst for the synthesis of acryloyloxyethyltrimethylammonium chloride comprises the following steps:

[0074] S1. Add 4,4'-azodibenzoic acid, ZrCl4, and N,N-dimethylformamide to a reactor, add 38 wt% hydrochloric acid, control the stirring rate to 400 rpm, and continue stirring at 125°C for 24 hours. After that, centrifuge, wash, and dry to obtain a MOF framework intermediate, labeled as UiO-66-AZO, wherein the mass ratio of 4,4'-azodibenzoic acid, ZrCl4, N,N-dimethylformamide, and hydrochloric acid is 1:1.2:10:0.5;

[0075] S2. Dispersing UiO-66-AZO in N,N-dimethylformamide, adding an activator, stirring continuously for 2.5 hours at room temperature, and then adding N,N,N-trimethyl-1-dodecylammonium bromide. The stirring rate is controlled to 400 rpm, and the mixture is stirred continuously for 24 hours at 60°C, followed by centrifugal washing and drying to obtain a catalyst precursor, wherein the activator is composed of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide in a molar ratio of 1:3, and the mass ratio of UiO-66-AZO, N,N-dimethylformamide, activator and N,N,N-trimethyl-1-dodecylammonium bromide is 1:10:1.4:4;

[0076] S3, dissolving CoCl2•6H2O and FeCl3•6H2O in deionized water in a mass ratio of 1:2.8:10, adding ammonia water dropwise under nitrogen protection to adjust the pH to 10, heating to 140°C, stirring continuously for 4 hours, and then separating, washing, and drying to obtain CoFe2O4 nanoparticles;

[0077] S4. Disperse 3 parts of CoFe2O4 nanoparticles in 18 parts of ethanol by weight, add 6 parts of catalyst precursor, control the stirring rate to 400 rpm, continue stirring at 70°C for 3 hours, then separate, wash and dry to obtain a MOFs-supported quaternary ammonium base catalyst.

[0078] Comparative Example 6

[0079] A method for preparing a MOFs-supported quaternary ammonium base catalyst for the synthesis of acryloyloxyethyltrimethylammonium chloride comprises the following steps:

[0080] S1. Add terephthalic acid, ZrCl4, and N,N-dimethylformamide to a reactor, add 38 wt% hydrochloric acid, control the stirring rate to 400 rpm, and continue stirring at 125° C. for 24 h, then centrifuge, wash, and dry to obtain UiO-66, wherein the mass ratio of terephthalic acid, ZrCl4, N,N-dimethylformamide, and hydrochloric acid is 1:1.2:10:0.5;

[0081] S2. Dispersing UiO-66 in N,N-dimethylformamide, adding an activator, stirring continuously for 2.5 hours at room temperature, then adding N,N,N-trimethyl-1-dodecylammonium bromide, controlling the stirring rate to 400 rpm, stirring continuously for 24 hours at 60°C, and then centrifuging, washing, and drying to obtain a catalyst precursor, wherein the activator is composed of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide in a molar ratio of 1:3, and the mass ratio of UiO-66-AZO, N,N-dimethylformamide, activator, and N,N,N-trimethyl-1-dodecylammonium bromide is 1:10:1.4:4;

[0082] S3, dissolving CoCl2•6H2O and FeCl3•6H2O in deionized water in a mass ratio of 1:2.8:10, adding ammonia water dropwise under nitrogen protection to adjust the pH to 10, heating to 140°C, stirring continuously for 4 hours, and then separating, washing, and drying to obtain CoFe2O4 nanoparticles;

[0083] S4. Disperse 3 parts of CoFe2O4 nanoparticles in 18 parts of ethanol by weight, add 6 parts of catalyst precursor and 0.5 parts of sodium dodecylbenzenesulfonate, control the stirring rate to 400 rpm, continue stirring at 70°C for 3 hours, then separate, wash and dry to obtain a MOFs-supported quaternary ammonium base catalyst.

[0084] Performance Testing

[0085] 0.5 g of MOFs-supported quaternary ammonium base catalyst, 10 mmol of hydroxyethyl acrylate, and 12 mmol of trimethylammonium chloride were added to 50 mL of ethanol and reacted at 80°C under nitrogen for 4 h. The reaction solution was analyzed by high-performance liquid chromatography, and the conversion and selectivity were calculated. After the reaction, the catalyst was recovered by separation using a 0.5 T external magnetic field, washed three times with ethanol, dried, and reused in the next reaction. The conversion retention after five cycles was recorded. 0.5 g of the catalyst was dispersed in 50 mL of ethanol and subjected to a 0.5 T magnetic field. The time required for complete separation was recorded, and the recovery was calculated. The test results are shown in Table 1.

[0086] Table 1

[0087]

[0088] The test results show that the MOFs-supported quaternary ammonium base catalysts prepared in Examples 1-4 all performed well in terms of catalytic activity, cyclic stability, selectivity, magnetic separation performance, and morphology. In contrast, the performance of Comparative Examples 1-6 was significantly reduced due to the lack of key steps or components. For example, Comparative Example 1 did not add CoFe2O4 nanoparticles, resulting in poor magnetic separation performance and low recovery rate; Comparative Example 2 did not undergo activation treatment, resulting in fewer catalyst active sites and reduced conversion rate and selectivity; Comparative Example 3 used Fe3O4 nanoparticles instead of CoFe2O4 nanoparticles, resulting in weaker magnetism and slower separation speed; Comparative Example 4 used tetramethylammonium bromide instead of N,N,N-trimethyl-1-dodecylammonium bromide, resulting in a lower active center density and reduced catalytic performance; Comparative Example 5 did not add a dispersant, resulting in uneven distribution of the catalyst during the loading process, leading to performance fluctuations; Comparative Example 6 used terephthalic acid instead of 4,4'-azodibenzoic acid, which weakened the carrier's electron transfer ability and active site anchoring ability, affecting overall performance. In summary, the catalysts prepared in Examples 1-4 of the present invention have excellent comprehensive performance, can effectively solve the problems existing in traditional catalysts, and have good application prospects in the synthesis of acryloyloxyethyltrimethylammonium chloride.

[0089] The above contents are merely examples and explanations of the present invention. Those skilled in the art may make various modifications or additions to the described specific embodiments or replace them in similar ways. As long as they do not deviate from the invention or exceed the scope defined by the claims, they should all fall within the scope of protection of the present invention.

Claims

1. A method for preparing a MOFs-supported quaternary ammonium base catalyst for the synthesis of acryloyloxyethyltrimethylammonium chloride, characterized in that: The method comprises the following preparation steps: S1. Dissolve 4,4'-azodibenzoic acid and ZrCl4 in N,N-dimethylformamide, add 35-40wt% hydrochloric acid, stir continuously at 118-125°C for 20-25h, then centrifuge, wash and dry to obtain a MOF framework intermediate, labeled as UiO-66-AZO; S2. Disperse UiO-66-AZO in N,N-dimethylformamide, add an activator, and continue stirring at room temperature for 1-3 hours. Then, add N,N,N-trimethyl-1-dodecylammonium bromide, continue stirring at 58-65°C for 20-25 hours, and then centrifuge, wash, and dry to obtain a catalyst precursor. S3, dissolving CoCl2•6H2O and FeCl3•6H2O in deionized water, adding ammonia water dropwise under nitrogen protection to adjust the pH, then heating to 130-140°C, stirring continuously for 3-6 hours, and then separating, washing, and drying to obtain CoFe2O4 nanoparticles; S4, dispersing CoFe2O4 nanoparticles in ethanol, adding a catalyst precursor and a dispersant, stirring continuously at 60-70°C for 2-4 hours, and then separating, washing, and drying to obtain a MOFs-supported quaternary ammonium base catalyst; In step S1, the mass ratio of 4,4'-azodibenzoic acid, ZrCl4, N,N-dimethylformamide and hydrochloric acid is 1:0.8-1.3:5-10:0.08-0.6, the activator in step S2 is composed of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide in a molar ratio of 1:1-3, the mass ratio of UiO-66-AZO, N,N-dimethylformamide, activator and N,N,N-trimethyl-1-dodecylammonium bromide is 1:8-12:0.8-1.5:2-4, and the step S4 comprises 1-3 parts of CoFe2O4 nanoparticles, 15-20 parts of ethanol, 2-6 parts of catalyst precursor and 0.3-0.5 parts of dispersant in parts by weight.

2. The preparation method according to claim 1, characterized in that In step S3, the pH is adjusted to 9-11.

3. The preparation method according to claim 1, characterized in that In step S3, the mass ratio of CoCl2•6H2O to FeCl3•6H2O is 1:2.3-2.

8.

4. The preparation method according to claim 1, characterized in that The dispersant in step S4 is at least one of polyethylene glycol, sodium dodecylbenzenesulfonate and oleic acid.

5. A MOFs-supported quaternary ammonium base catalyst for the synthesis of acryloyloxyethyltrimethylammonium chloride, characterized in that: The catalyst is prepared by the preparation method of the MOFs-supported quaternary ammonium base catalyst used for the synthesis of acryloyloxyethyltrimethylammonium chloride according to any one of claims 1 to 4.

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