MOFs supported quaternary ammonium base catalyst applied to synthesis of acryloyloxyethyl trimethyl ammonium chloride and preparation method of MOFs supported quaternary ammonium base catalyst

Abstract

The invention relates to the technical field of catalyst processing, and particularly discloses an MOFs supported quaternary ammonium base catalyst applied to synthesis of acryloyloxyethyl trimethyl ammonium chloride and a preparation method of the MOFs supported quaternary ammonium base catalyst. The preparation method comprises the following steps: firstly, preparing UiO-66-AZO from 4, 4 '-azodibenzoic acid and ZrCl4, then activating and grafting quaternary ammonium salt to obtain a catalyst precursor, and finally, mixing and loading self-made CoFe2O4 nanoparticles, the catalyst precursor and a dispersing agent in ethanol. The high specific surface area of the UiO-66-AZO in the catalyst provides abundant active sites, the quaternary ammonium base group enhances the alkaline catalytic ability, and the CoFe2O4 endows the magnetic separation characteristic. In the synthesis of acryloyloxyethyl trimethyl ammonium chloride, the catalyst shows high activity, excellent cycle stability and high selectivity, meanwhile, the problem of separation of a homogeneous catalyst is avoided, and the green chemical requirement is met.

Description

Technical Field

[0001] The present invention relates to the technical field of catalysts, and more specifically, it relates to a MOFs-supported quaternary ammonium base catalyst applied to the synthesis of acryloyloxyethyl trimethyl ammonium chloride and a preparation method thereof. Background Art

[0002] Acryloyloxyethyl trimethyl ammonium chloride is an important cationic monomer, which is widely used as a flocculant and a modifier for polymer materials in the fields of water treatment, papermaking, textile, etc. Its synthesis usually involves a quaternization reaction, which needs to be carried out under the action of a basic catalyst. The traditional process uses a homogeneous quaternary ammonium base as the catalyst, but there are problems such as difficult catalyst separation, low recycling efficiency, complex product purification, and environmental pollution. Therefore, the development of an efficient and easily recyclable supported quaternary ammonium base catalyst has become a research hotspot in this field.

[0003] Metal-organic frameworks (MOFs) have shown great potential in the aspect of catalyst carriers due to their high specific surface area, good thermal stability, and adjustable pore structure. Especially when MOFs are used as carriers, different active sites can be introduced through surface functionalization, so as to achieve effective catalysis for specific reactions. In the prior art, the introduction of quaternary ammonium groups into MOFs can enhance the alkalinity, but the loading efficiency of the quaternary ammonium base and the pore compatibility of MOFs have not been systematically optimized, which easily leads to the loss of active components. In addition, the recycling of the catalyst still relies on centrifugation or filtration, and it is difficult to achieve industrial continuous operation. Based on this, the present invention provides a MOFs-supported quaternary ammonium base catalyst applied to the synthesis of acryloyloxyethyl trimethyl ammonium 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 applied to the synthesis of acryloyloxyethyl trimethyl ammonium chloride and a preparation method thereof. The catalyst prepared by the present invention shows high activity, excellent cycle stability, and high selectivity in the synthesis of acryloyloxyethyl trimethyl ammonium chloride, and at the same time avoids the problem of separation of homogeneous catalysts, meeting the requirements of green chemistry.

[0005] In the first aspect, the present invention provides a preparation method of a MOFs-supported quaternary ammonium base catalyst applied to the synthesis of acryloyloxyethyl trimethyl ammonium chloride, adopting the following technical scheme:

[0006] A preparation method of a MOFs-supported quaternary ammonium base catalyst applied to the synthesis of acryloyloxyethyl trimethyl ammonium chloride includes the following preparation steps:

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

[0008] S2. Disperse UiO-66-AZO in N,N-dimethylformamide, add an activator, continuously stir at room temperature for 1-3 h, then add trimethyl(dodecyl)ammonium bromide, continuously stir at 58-65 °C for 20-25 h, then centrifuge, wash, and dry to obtain the catalyst precursor;

[0009] S3. Dissolve CoCl2•6H2O and FeCl3•6H2O in deionized water, under nitrogen protection, add ammonia water to adjust the pH, then heat up to 130-140 °C, continuously stir for 3-6 h, then separate, wash, and dry to obtain CoFe2O4 nanoparticles;

[0010] S4. Disperse CoFe2O4 nanoparticles in ethanol, add the catalyst precursor and a dispersant, continuously stir at 60-70 °C for 2-4 h, then separate, wash, and dry. What is obtained is the 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, in step S2, the activator is composed of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide with a molar ratio of 1: (1-3).

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

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

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

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

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

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

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

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

[0021] The present invention prepares a catalyst with a UiO-66-AZO metal-organic framework as the carrier, covalently grafted quaternary ammonium base active sites and composite with magnetic CoFe2O4 nanoparticles. The UiO-66-AZO carrier uses 4,4'-azodibenzoic acid as the ligand to form a porous framework with a high specific surface area with ZrCl4 under solvothermal conditions. Its azo group not only enhances the electron transfer ability but also provides an anchoring site for subsequent quaternary ammonium base grafting; the quaternary ammonium base active center is covalently immobilized on the surface of MOFs through the EDC / NHS system with amide bonds to form high-density basic sites, significantly improving the conversion rate and selectivity of the synthesis of acryloyloxyethyltrimethylammonium chloride, and at the same time avoiding the loss of active components caused by physical adsorption; CoFe2O4 magnetic particles are synthesized by the co-precipitation-hydrothermal method, and its spinel structure endows strong magnetism. Combined with the interface composite stably regulated by hydrogen bonding and steric hindrance effect of the dispersant, the catalyst can be quickly separated by an external magnetic field, preventing the shedding of magnetic particles and optimizing the distribution of active sites.

[0022] In summary, the catalyst prepared by the present invention not only realizes efficient catalysis through the porosity of MOFs and the strong basicity of quaternary ammonium base, but also simplifies the separation process by using the magnetic core, combines the covalent grafting and interface stabilization processes, and solves the problems of easy loss of active sites and high energy consumption for recovery of traditional catalysts. In the synthesis of acryloyloxyethyltrimethylammonium chloride, its high activity, high selectivity and magnetic recoverable characteristics significantly reduce production costs and environmental pollution, providing a solution for the industrial application of green chemical processes. Specific embodiments

[0023] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

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

[0025] Polyethylene glycol, purchased from Liaoning Kelong Fine Chemical Co., Ltd., CAS 25322-68-3;

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

[0027] Example 1

[0028] A preparation method of a MOF-supported quaternary ammonium base catalyst for the synthesis of acryloyloxyethyltrimethylammonium chloride, comprising the following preparation steps:

[0029] S1. Add 4,4'-azodibenzoic acid, ZrCl4 and N,N-dimethylformamide to the reaction kettle, add hydrochloric acid with a concentration of 35 wt%, control the stirring rate at 200 rpm, and continuously stir at 118 °C for 25 h, then 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 1:0.8:5:0.08;

[0030] S2. Disperse UiO-66-AZO in N,N-dimethylformamide, add an activator, continuously stir at room temperature for 3 h, then add trimethyl(dodecyl)ammonium bromide, control the stirring rate at 200 rpm, and continuously stir at 58 °C for 25 h, then centrifuge, wash and dry to obtain a catalyst precursor, wherein the activator is composed of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide with a molar ratio of 1:1, and the mass ratio of UiO-66-AZO, N,N-dimethylformamide, activator and trimethyl(dodecyl)ammonium bromide is 1:8:0.8:2;

[0031] S3. Dissolve CoCl2•6H2O and FeCl3•6H2O in deionized water according to a mass ratio of 1:2.3:7, dropwise add ammonia water under nitrogen protection to adjust the pH to 9, raise the temperature to 130 °C, continuously stir for 6 h, then separate, wash and dry 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 part of oleic acid, control the stirring rate at 200 rpm, continuously stir at 60 °C for 4 h, then separate, wash and dry. What is obtained is the quaternary ammonium base catalyst supported on MOFs.

[0033] Example 2

[0034] A preparation method of a quaternary ammonium base catalyst supported on MOFs for the synthesis of acryloyloxyethyl trimethyl ammonium chloride, comprising the following preparation steps:

[0035] S1. Add 4,4'-azodibenzoic acid, ZrCl₄ and N,N-dimethylformamide to a reaction kettle, add hydrochloric acid with a concentration of 36 wt%, control the stirring rate at 220 rpm, continuously stir at 120 °C for 24 h, then centrifuge, wash and dry to obtain an MOF framework intermediate, labeled as UiO-66-AZO, where the mass ratio of 4,4'-azodibenzoic acid, ZrCl₄, N,N-dimethylformamide and hydrochloric acid is 1:1.1:7:0.3;

[0036] S2. Disperse UiO-66-AZO in N,N-dimethylformamide, add an activator, continuously stir at room temperature for 2 h, then add trimethyl(dodecyl)ammonium bromide, control the stirring rate at 220 rpm, continuously stir at 60 °C for 24 h, then centrifuge, wash and dry to obtain a catalyst precursor, where the activator consists of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide with a molar ratio of 1:2, and the mass ratio of UiO-66-AZO, N,N-dimethylformamide, activator and trimethyl(dodecyl)ammonium bromide is 1:9:1.2:3;

[0037] S3. Dissolve CoCl₂·6H₂O and FeCl₃·6H₂O in deionized water according to a mass ratio of 1:2.4:8, under nitrogen protection, add ammonia water to adjust the pH to 10, raise the temperature to 135 °C, continuously stir for 5 h, then separate, wash and dry 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 part of sodium dodecylbenzenesulfonate, control the stirring rate at 300 rpm, continuously stir at 63 °C for 3.8 h, then separate, wash and dry. What is obtained is the quaternary ammonium base catalyst supported on MOFs.

[0039] Example 3

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

[0041] S1. Add 4,4'-azodibenzoic acid, ZrCl4 and N,N-dimethylformamide into a reaction kettle, add hydrochloric acid with a concentration of 40 wt%, control the stirring rate at 400 rpm, continuously stir at 125 °C for 20 h, then 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 1:1.3:10:0.6;

[0042] S2. Disperse UiO-66-AZO in N,N-dimethylformamide, add an activator, continuously stir at room temperature for 3 h, then add trimethyl(dodecyl)ammonium bromide, control the stirring rate at 400 rpm, continuously stir at 65 °C for 20 h, then centrifuge, wash and dry to obtain a catalyst precursor, wherein the activator is composed of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide with a molar ratio of 1:3, and the mass ratio of UiO-66-AZO, N,N-dimethylformamide, activator and trimethyl(dodecyl)ammonium bromide is 1:12:1.5:4;

[0043] S3. Dissolve CoCl2•6H2O and FeCl3•6H2O in deionized water according to a mass ratio of 1:2.8:10, dropwise add ammonia water under nitrogen protection to adjust the pH to 11, raise the temperature to 140 °C, continuously stir for 3 h, then separate, wash and dry to obtain CoFe2O4 nanoparticles;

[0044] S4. By weight, disperse 3 parts of CoFe2O4 nanoparticles in 20 parts of ethanol, add 6 parts of the catalyst precursor and 0.5 part of polyethylene glycol, control the stirring rate at 400 rpm, continuously stir at 60 °C for 2 h, then separate, wash and dry, and the obtained product is the MOFs-supported quaternary ammonium base catalyst.

[0045] Example 4

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

[0047] S1. Add 4,4'-azodibenzoic acid, ZrCl4 and N,N-dimethylformamide into a reaction kettle, add hydrochloric acid with a concentration of 38 wt%, control the stirring rate at 400 rpm, continuously stir at 125 °C for 24 h, then centrifuge, wash and dry to obtain the MOF framework intermediate, labeled as UiO-66-AZO, where the mass ratio of 4,4'-azodibenzoic acid, ZrCl4, N,N-dimethylformamide and hydrochloric acid is 1:1.2:10:0.5;

[0048] S2. Disperse UiO-66-AZO in N,N-dimethylformamide, add an activator, continuously stir at room temperature for 2.5 h, then add trimethyl(dodecyl)ammonium bromide, control the stirring rate at 400 rpm, continuously stir at 60 °C for 24 h, then centrifuge, wash and dry to obtain the catalyst precursor, where the activator consists of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide with a molar ratio of 1:3, and the mass ratio of UiO-66-AZO, N,N-dimethylformamide, the activator and trimethyl(dodecyl)ammonium bromide is 1:10:1.4:4;

[0049] S3. Dissolve CoCl2•6H2O and FeCl3•6H2O in deionized water according to the mass ratio of 1:2.8:10, under nitrogen protection, add ammonia water to adjust the pH to 10, raise the temperature to 140 °C, continuously stir for 4 h, then separate, wash and dry to obtain CoFe2O4 nanoparticles;

[0050] S4. By weight, disperse 3 parts of CoFe2O4 nanoparticles in 18 parts of ethanol, add 6 parts of the catalyst precursor and 0.5 part of sodium dodecylbenzenesulfonate, control the stirring rate at 400 rpm, continuously stir at 70 °C for 3 h, then separate, wash and dry, and the obtained product is the MOFs-supported quaternary ammonium base catalyst.

[0051] Comparative Example 1

[0052] A preparation method of an MOFs-supported quaternary ammonium base catalyst applied to the synthesis of acryloyloxyethyltrimethylammonium chloride, comprising the following preparation steps:

[0053] S1. Add 4,4'-azodibenzoic acid, ZrCl4 and N,N-dimethylformamide into a reaction kettle, add hydrochloric acid with a concentration of 38 wt%, control the stirring rate at 400 rpm, continuously stir at 125 °C for 24 h, then centrifuge, wash and dry to obtain the MOF framework intermediate, labeled as UiO-66-AZO, where the mass ratio of 4,4'-azodibenzoic acid, ZrCl4, N,N-dimethylformamide and hydrochloric acid is 1:1.2:10:0.5;

[0054] S2. Disperse UiO-66-AZO in N,N-dimethylformamide, add an activator, continuously stir for 2.5 h at room temperature, then add trimethyl(dodecyl)ammonium bromide, control the stirring rate at 400 rpm, continuously stir at 60 °C for 24 h, then centrifuge, wash, and dry. What is obtained is the quaternary ammonium base catalyst supported by MOFs. The activator is composed of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide with a molar ratio of 1:3. The mass ratio of UiO-66-AZO, N,N-dimethylformamide, the activator, and trimethyl(dodecyl)ammonium bromide is 1:10:1.4:4;

[0055] Comparative Example 2

[0056] A preparation method of a quaternary ammonium base catalyst supported by MOFs for the synthesis of acryloyloxyethyltrimethylammonium chloride, comprising the following preparation steps:

[0057] S1. Add 4,4'-azodibenzoic acid, ZrCl4, and N,N-dimethylformamide to a reaction kettle, add hydrochloric acid with a concentration of 38 wt%, control the stirring rate at 400 rpm, continuously stir at 125 °C for 24 h, then centrifuge, wash, and dry to obtain an MOF framework intermediate, labeled as UiO-66-AZO. The mass ratio of 4,4'-azodibenzoic acid, ZrCl4, N,N-dimethylformamide, and hydrochloric acid is 1:1.2:10:0.5;

[0058] S2. Disperse UiO-66-AZO in N,N-dimethylformamide, add trimethyl(dodecyl)ammonium bromide, control the stirring rate at 400 rpm, continuously stir at 60 °C for 24 h, then centrifuge, wash, and dry to obtain a catalyst precursor. The mass ratio of UiO-66-AZO, N,N-dimethylformamide, and trimethyl(dodecyl)ammonium bromide is 1:10:4;

[0059] S3. Dissolve CoCl2•6H2O and FeCl3•6H2O in deionized water according to a mass ratio of 1:2.8:10, under nitrogen protection, dropwise add ammonia water to adjust the pH to 10, raise the temperature to 140 °C, continuously stir for 4 h, then separate, wash, and dry to obtain CoFe2O4 nanoparticles;

[0060] S4. By weight, disperse 3 parts of CoFe2O4 nanoparticles in 18 parts of ethanol, add 6 parts of the catalyst precursor and 0.5 part of sodium dodecylbenzenesulfonate, control the stirring rate at 400 rpm, continuously stir at 70 °C for 3 h, then separate, wash, and dry. What is obtained is the quaternary ammonium base catalyst supported by MOFs.

[0061] Comparative Example 3

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

[0063] S1. Add 4,4'-azodibenzoic acid, ZrCl4 and N,N-dimethylformamide into a reaction kettle, add hydrochloric acid with a concentration of 38 wt%, control the stirring rate at 400 rpm, continuously stir at 125 °C for 24 h, then 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. Disperse UiO-66-AZO in N,N-dimethylformamide, add an activator, continuously stir at room temperature for 2.5 h, then add trimethyl(dodecyl)ammonium bromide, control the stirring rate at 400 rpm, continuously stir at 60 °C for 24 h, then centrifuge, wash and dry to obtain a catalyst precursor, wherein the activator is composed of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide with a molar ratio of 1:3, and the mass ratio of UiO-66-AZO, N,N-dimethylformamide, the activator and trimethyl(dodecyl)ammonium bromide is 1:10:1.4:4;

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

[0066] Comparative Example 4

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

[0068] S1. Add 4,4'-azodibenzoic acid, ZrCl4 and N,N-dimethylformamide into a reaction kettle, add hydrochloric acid with a concentration of 38 wt%, control the stirring rate at 400 rpm, continuously stir at 125 °C for 24 h, then 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. Disperse UiO-66-AZO in N,N-dimethylformamide, add an activator, continuously stir at room temperature for 2.5 h, then add tetrabutylammonium bromide, control the stirring rate at 400 rpm, continuously stir at 60 °C for 24 h, and then centrifuge, wash and dry to obtain a catalyst precursor. The activator is composed of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide with a molar ratio of 1:3. The mass ratio of UiO-66-AZO, N,N-dimethylformamide, the activator and tetrabutylammonium bromide is 1:10:1.4:4;

[0070] S3. Dissolve CoCl2•6H2O and FeCl3•6H2O in deionized water according to a mass ratio of 1:2.8:10, add ammonia water under nitrogen protection to adjust the pH to 10, raise the temperature to 140 °C, continuously stir for 4 h, and then separate, wash and dry to obtain CoFe2O4 nanoparticles;

[0071] S4. By weight, disperse 3 parts of CoFe2O4 nanoparticles in 18 parts of ethanol, add 6 parts of the catalyst precursor and 0.5 part of sodium dodecylbenzenesulfonate, control the stirring rate at 400 rpm, continuously stir at 70 °C for 3 h, and then separate, wash and dry. What is obtained is the MOFs-supported quaternary ammonium base catalyst.

[0072] Comparative Example 5

[0073] A preparation method of an MOFs-supported quaternary ammonium base catalyst for the synthesis of acryloyloxyethyltrimethylammonium chloride, comprising the following preparation steps:

[0074] S1. Add 4,4'-azodibenzoic acid, ZrCl4 and N,N-dimethylformamide to a reaction kettle, add hydrochloric acid with a concentration of 38 wt%, control the stirring rate at 400 rpm, continuously stir at 125 °C for 24 h, and then centrifuge, wash and dry to obtain an MOF framework intermediate, labeled as UiO-66-AZO. The mass ratio of 4,4'-azodibenzoic acid, ZrCl4, N,N-dimethylformamide and hydrochloric acid is 1:1.2:10:0.5;

[0075] S2. Disperse UiO-66-AZO in N,N-dimethylformamide, add an activator, continuously stir at room temperature for 2.5 h, then add trimethyl(dodecyl)ammonium bromide, control the stirring rate at 400 rpm, continuously stir at 60 °C for 24 h, and then centrifuge, wash and dry to obtain a catalyst precursor. The activator is composed of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide with a molar ratio of 1:3. The mass ratio of UiO-66-AZO, N,N-dimethylformamide, the activator and trimethyl(dodecyl)ammonium bromide is 1:10:1.4:4;

[0076] S3. Dissolve CoCl₂•6H₂O and FeCl₃•6H₂O in deionized water according to the mass ratio of 1:2.8:10. Under nitrogen protection, add ammonia water to adjust the pH to 10, heat up to 140 °C, continuously stir for 4 h, then separate, wash and dry to obtain CoFe₂O₄ nanoparticles;

[0077] S4. By weight, disperse 3 parts of CoFe₂O₄ nanoparticles in 18 parts of ethanol, add 6 parts of catalyst precursor, control the stirring rate at 400 rpm, continuously stir at 70 °C for 3 h, then separate, wash and dry. What is obtained is the MOF-supported quaternary ammonium base catalyst.

[0078] Comparative Example 6

[0079] A preparation method of an MOF-supported quaternary ammonium base catalyst for the synthesis of acryloyloxyethyltrimethylammonium chloride, comprising the following preparation steps:

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

[0081] S2. Disperse UiO-66 in N,N-dimethylformamide, add an activator, continuously stir at room temperature for 2.5 h, then add N,N,N-trimethyl-1-dodecylammonium bromide, control the stirring rate at 400 rpm, continuously stir at 60 °C for 24 h, then centrifuge, wash and dry to obtain the catalyst precursor, where the activator consists of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide with 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. Dissolve CoCl₂•6H₂O and FeCl₃•6H₂O in deionized water according to the mass ratio of 1:2.8:10. Under nitrogen protection, add ammonia water to adjust the pH to 10, heat up to 140 °C, continuously stir for 4 h, then separate, wash and dry 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 part of sodium dodecylbenzenesulfonate, control the stirring rate at 400 rpm, continuously stir at 70 °C for 3 h, then separate, wash and dry. The obtained product is the quaternary ammonium base catalyst supported on MOFs.

[0084] Performance test

[0085] Add 0.5 g of the quaternary ammonium base catalyst supported on MOFs, 10 mmol of 2-hydroxyethyl acrylate and 12 mmol of trimethylammonium chloride to 50 mL of ethanol, and react at 80 °C under nitrogen protection for 4 h. Analyze the reaction solution by high performance liquid chromatography and then calculate the conversion rate and selectivity; after the reaction, separate and recover the catalyst by applying an external magnetic field of 0.5 T, wash it 3 times with ethanol and then dry it, and reuse it for the next round of reaction. Record the conversion rate retention rate after 5 cycles; disperse 0.5 g of the catalyst in 50 mL of ethanol, apply a magnetic field of 0.5 T, record the time required for complete separation, and calculate the recovery rate. The test results are shown in Table 1.

[0086] Table 1

[0087]

[0088] It can be seen from the test results that the quaternary ammonium base catalysts supported on MOFs prepared in Examples 1-4 show excellent performance in terms of catalytic activity, cycle stability, selectivity, magnetic separation performance and morphology structure. In contrast, due to the lack of key steps or components in Comparative Examples 1-6, their performance decreased significantly. For example, in Comparative Example 1, no CoFe2O4 nanoparticles were added, resulting in poor magnetic separation performance and low recovery rate; in Comparative Example 2, no activation treatment was carried out, there were fewer active sites on the catalyst, and the conversion rate and selectivity decreased; in Comparative Example 3, Fe3O4 nanoparticles were used instead of CoFe2O4 nanoparticles, with weaker magnetism and slower separation speed; in Comparative Example 4, tetramethylammonium bromide was used instead of N,N,N-trimethyl-1-dodecylammonium bromide, with a lower density of active centers and a decrease in catalytic performance; in Comparative Example 5, no dispersant was added, and the catalyst was unevenly distributed during the loading process, resulting in performance fluctuations; in Comparative Example 6, terephthalic acid was used instead of 4,4'-azodibenzoic acid, weakening the electron transfer ability and the ability to anchor active sites of the carrier, and affecting the 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 acryloyloxyethyl trimethylammonium chloride.

[0089] The above content is only an example and illustration of the present invention. Those skilled in the art of this technology can make various modifications or supplements to the described specific embodiments or use similar methods for substitution. As long as they do not deviate from the invention or exceed the scope defined by this claim book, they should all fall within the protection scope of the present invention.

Claims

1. A MOF-supported quaternary ammonium base catalyst for the synthesis of acryloyloxyethyltrimethylammonium chloride, characterized in that, The MOF-supported quaternary ammonium base catalyst is prepared by the following steps: S1. Dissolve 4,4'-azodibenzoic acid and ZrCl4 in N,N-dimethylformamide, add hydrochloric acid, and obtain an MOF framework intermediate, labeled as UiO-66-AZO, through solvothermal reaction, solid-liquid separation, washing, and drying. S2. Disperse UiO-66-AZO in N,N-dimethylformamide, add an activator for surface activation, and then add trimethyl(dodecyl)ammonium bromide for quaternization modification. Obtain a catalyst precursor through centrifugation, washing, and drying. S3. Dissolve CoCl2•6H2O and FeCl3•6H2O in deionized water, add ammonia water under the protection of an inert gas to adjust the pH, and obtain CoFe2O4 nanoparticles through hydrothermal reaction, separation and purification, and drying. S4. Disperse the CoFe2O4 nanoparticles in ethanol, add the catalyst precursor and a dispersant, and perform a loading treatment. Obtain the MOF-supported quaternary ammonium base catalyst through separation, washing, and drying.

2. The MOF-supported quaternary ammonium base catalyst according to claim 1, wherein 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).

3. The quaternary ammonium base catalyst supported on MOFs according to claim 1, wherein In step S2, the activator is composed of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide with a molar ratio of 1:(1 - 3).

4. The MOF-supported quaternary ammonium base catalyst according to claim 1, wherein In step S2, the mass ratio of UiO-66-AZO, N,N-dimethylformamide, the activator, and trimethyl(dodecyl)ammonium bromide is 1:(8 - 12):(0.8 - 1.5):(2 - 4).

5. The MOF-supported quaternary ammonium base catalyst according to claim 1, wherein In step S3, the pH is adjusted to 9 - 11.

6. The MOF-supported quaternary ammonium base catalyst according to claim 1, wherein In step S3, the mass ratio of CoCl2•6H2O and FeCl3•6H2O is 1:(2.3 - 2.8).

7. The MOF-supported quaternary ammonium base catalyst according to claim 1, wherein In step S4, the dispersant is at least one of polyethylene glycol, sodium dodecylbenzenesulfonate, and oleic acid.

8. The quaternary ammonium base catalyst supported on MOFs according to claim 1, wherein, In step S4, by weight, it is 1 - 3 parts of CoFe2O4 nanoparticles, 15 - 20 parts of ethanol, 2 - 6 parts of the catalyst precursor, and 0.3 - 0.5 parts of the dispersant.

9. A MOF-supported quaternary ammonium base catalyst applied to the synthesis of acryloyloxyethyl trimethyl ammonium chloride, characterized in that, Prepared by the preparation method of the MOF-supported quaternary ammonium base catalyst for the synthesis of acryloyloxyethyltrimethylammonium chloride according to any one of claims 1 - 8.

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