Ionic covalent organic framework coupling metal salt material as well as preparation method and application thereof

Abstract

The invention provides an ionic covalent organic framework coupled metal salt material as well as a preparation method and application thereof, and relates to the technical field of catalytic synthesis of carbonic ester. The defects in the prior art are overcome, and the ionic covalent organic framework coupling metal salt material is obtained by copolymerizing an aromatic aldehyde group-containing monomer and an aromatic amino monomer according to a certain proportion to obtain an ionic covalent organic framework precursor, and then sulfonating and carrying out ion exchange. The ionic covalent organic framework coupled metal salt material can realize efficient conversion of an epoxy compound and CO2 to produce cyclic carbonate, and the yield of the cyclic carbonate can reach 97%; the ionic covalent organic framework coupling metal salt material can be easily separated from reactants and products and can be recycled.

Description

Technical Field

[0001] The present invention relates to the technical field of catalytic synthesis of carbonates, and particularly relates to an ionic covalent organic framework coupled with a metal salt material, a preparation method thereof, and an application thereof. Background Art

[0002] Effective utilization of CO2 has always been a hot topic widely studied in the field of chemical synthesis. Capturing and converting CO2 into high-value chemicals is an important way to reduce dependence on fossil fuels. Among them, synthesizing cyclic carbonates from CO2 and various alkylene oxides is one of the ways with good atom economy and great potential, and has important research significance and application value.

[0003] In the reaction of synthesizing cyclic carbonates from CO2 and various alkylene oxides, the most widely used is the synthesis of ethylene carbonate from CO2 and ethylene oxide. It is an excellent aprotic solvent and is widely used in the synthesis of bulk chemicals such as dimethyl carbonate and ethylene glycol, as well as fine chemical products such as pharmaceuticals and engineering plastics. Such reactions usually require high temperature, high pressure, and a catalyst. The performance of the catalyst indirectly determines the reaction conditions and production costs. The catalysts for this reaction can be divided into homogeneous catalysts and heterogeneous catalysts.

[0004] Homogeneous catalysts are currently widely used in industrial production and mainly include quaternary ammonium salts, quaternary phosphonium salts, imidazole-based ionic liquids, etc. Since the homogeneous catalytic system has the catalyst, reactants, and products in the same phase, its separation and recovery processes are complex and energy-consuming, resulting in an increase in production costs and limited development prospects in industrial production. The activity of the catalyst can be improved by adding certain metal salts. For example, CN 105126912A discloses a method for preparing ethylene carbonate derivatives by cycloaddition of ethylene oxide derivatives and CO2 catalyzed by an imidazole-based ionic liquid-zinc halide / alkali system, which has high activity, a wide substrate adaptation range in a short time under mild conditions, but has problems of large dosage and poor stability.

[0005] Heterogeneous catalysts have high stability and are easy to separate in the reaction system, and are currently the focus of industrial catalysis research. They mainly include ion exchange resin-type catalysts, catalysts loaded with alkali metal salts or quaternary phosphonium salts, etc. Such catalysts have disadvantages such as low activity, large dosage, and short service life, and it is difficult to meet the requirements of industrial production. CN 105294643A discloses a method for preparing ethylene carbonate using a metal mixed oxide and a quaternary phosphonium salt co-catalyst. The catalytic system has a synergistic catalytic effect of multiple active centers, with less catalyst dosage and long service life, but has problems of high reaction pressure and long reaction time. CN 117358307A discloses a method for catalytic cycloaddition reaction using a styrene cross-linked copolymer resin grafted with a quaternary phosphonium salt containing inorganic nanomaterials. The catalyst has high activity and stability and is easy to separate, but has problems such as large catalyst usage and high toxicity of reagents used in preparation.

[0006] Synthesizing a high molecular polymer using small molecules with active centers is a way to convert homogeneous catalysts into heterogeneous catalysts. Such catalysts have the advantages of high activity of homogeneous catalysts and easy separation and good stability of heterogeneous catalysts. CN 115504954 B discloses a method for catalytically synthesizing cyclic carbonates based on high ion density polyionic liquids, which realizes the stable conversion of epoxides and has high product selectivity, but the catalyst has a single active center and requires relatively high reaction temperature and pressure. Therefore, for the reaction of synthesizing cyclic carbonates from CO2 and epoxides, it is necessary to further develop high-quality polyionic liquid catalysts with high activity, good selectivity and stability. Summary of the Invention

[0007] Aiming at the deficiencies of the prior art, the present invention provides an ionic covalent organic framework coupled with metal salt material and its application. The ionic covalent organic framework coupled with metal salt material is prepared by copolymerizing an aromatic aldehyde group-containing monomer and an aromatic amine group-containing monomer in a certain proportion to obtain an ionic covalent organic framework precursor, and then sulfonating and ion-exchanging; the application of the ionic covalent organic framework coupled with metal salt material in the catalytic preparation of cyclic carbonates can realize the efficient conversion of epoxides and CO2 to produce cyclic carbonates, and the yield of cyclic carbonates can reach 97%; the ionic covalent organic framework coupled with metal salt material is easy to separate from reactants and products and can be reused.

[0008] To achieve the above objectives, the technical solution of the present invention is realized through the following technical solutions:

[0009] An ionic covalent organic framework coupled with metal salt material, the structural formula of the ionic covalent organic framework coupled with metal salt material is shown as follows:

[0010] ;

[0011] In the formula: x, y, and z are each independently selected from any positive integer; M is any one or more of Co, Cu, Mn, Zn, Ni, etc.; X1 is any one or more of chloride ion, bromide ion, iodide ion, etc.; X2 is any one or more of chloride ion, bromide ion, iodide ion, acetate, trifluoroacetate, carboxylate, sulfate, bisulfate, phosphate, etc.

[0012] The preparation method of the above ionic covalent organic framework coupled with metal salt material includes the following steps:

[0013] S1. Using 1,3,5-tris(bromomethyl)benzene and 4-aminopyridine as reaction raw materials, and mesitylene as a solvent, react under the protection of an inert gas to obtain 1,3,5-tris(4-aminopyridine bromide)methylbenzene;

[0014] S2. Using 1,3,5-triformylphloroglucinol and the 1,3,5-tris(4-aminopyridinium bromide)methylbenzene prepared above as reaction raw materials, mesitylene as the solvent, adding glacial acetic acid to the solvent under the protection of an inert gas to prepare an ionic covalent organic framework precursor;

[0015] S3. Subjecting the above ionic covalent organic framework precursor to a sulfonation reaction to obtain an ionic covalent organic framework precursor with sulfonic acid functional groups;

[0016] S4. Dispersing the above ionic covalent organic framework precursor with sulfonic acid functional groups in an aqueous solution of a metal salt, performing an ion exchange reaction, and then washing and drying to obtain an ionic covalent organic framework coupled with a metal salt material.

[0017] Preferably, in step S1, the molar ratio of 1,3,5-tris(bromomethyl)benzene to 4-aminopyridine is 1:2.0 - 5.0, and the amount of the added solvent is 10 - 20 times the total weight of the reaction raw materials, the reaction temperature is 80 - 140 °C, and the reaction time is 2 - 6 h.

[0018] Preferably, in step S2, the molar ratio of 1,3,5-triformylphloroglucinol to 1,3,5-tris(4-aminopyridinium bromide)methylbenzene is 1:0.33 - 3, and the amount of added glacial acetic acid is 7 - 10 times the total weight of the reaction raw materials; the reaction temperature is 90 - 130 °C, and the reaction time is 1 - 3 h.

[0019] Preferably, in step S3, concentrated sulfuric acid is used for the sulfonation reaction, and the amount of concentrated sulfuric acid is 25 - 40 times the total weight of the ionic covalent organic framework precursor; and the sulfonation reaction temperature is 70 - 90 °C, and the reaction time is 24 - 36 h.

[0020] Preferably, in step S4, the concentration of the metal salt in the aqueous solution of the metal salt is 2 - 4 M, and the ion exchange reaction time is 24 - 36 h.

[0021] The above ionic covalent organic framework coupled with a metal salt material is applied to the catalytic synthesis of carbonates, and the application method is: using the ionic covalent organic framework coupled with a metal salt material as a catalyst to catalyze the synthesis of cyclic carbonates from epoxides and CO2.

[0022] Preferably, the epoxide is selected from at least one of ethylene oxide, propylene oxide, epichlorohydrin, 1,2-epoxybutane, styrene oxide, etc.

[0023] Preferably, the amount of the ionic covalent organic framework coupled with metal salt material added during the catalysis is 0.5 wt.% - 3 wt.% of the mass of the epoxide; and the reaction temperature of the catalytic reaction is 80 - 150 °C; the reaction pressure is 2 - 4 MPa; the reaction time is 2 - 6 h; the reaction general formula for catalytic synthesis is as follows:

[0024] ;

[0025] wherein R is one of a substituted or unsubstituted C1 - C15 straight-chain or branched-chain alkyl group, a substituted or unsubstituted C3 - C15 cycloalkyl group, a substituted or unsubstituted C3 - C15 heterocycloalkyl group, and a substituted or unsubstituted C6 - C15 aryl group, Cat. is the ionic covalent organic framework coupled with metal salt material as a catalyst, T represents the reaction temperature, and P represents the reaction pressure.

[0026] The present invention provides an ionic covalent organic framework coupled with metal salt material, its preparation method and application. Compared with the prior art, the advantages are as follows:

[0027] (1) The ionic covalent organic framework coupled with metal salt material of the present invention has high catalytic efficiency. This material combines the high specific surface area of ICOFs and the high catalytic performance of metal salts, and can achieve efficient catalytic conversion of CO2 and epoxides under mild conditions, with a high yield of cyclic carbonates;

[0028] (2) The ionic covalent organic framework coupled with metal salt material of the present invention has an easy-to-recycle effect. As a heterogeneous catalyst, this material is easy to separate from the reaction system and recycle for reuse, reducing the operating cost and environmental pollution;

[0029] (3) The ionic covalent organic framework coupled with metal salt material of the present invention has good stability. Metal ions are firmly loaded in the ICOFs framework through ion exchange, and are not easily detached or inactivated, ensuring the long-term stability and catalytic activity of the catalyst;

[0030] (4) The ionic covalent organic framework coupled with metal salt material of the present invention has a wide range of applications. By adjusting the structure of ICOFs and the type and loading amount of metal salts, composite materials with different catalytic properties can be prepared, which are suitable for different types of epoxides and reaction conditions;

[0031] (5) The catalytic system of the present invention uses CO2 and epoxides as raw materials, and the product cyclic carbonate is a green chemical, which conforms to the development concept of green chemistry. The innovative technology of using the ionic covalent organic framework and metal salt composite material to catalyze the cycloaddition of CO2 in the present invention provides new ideas and methods for solving the problem of CO2 resource utilization, and has important scientific significance and application value. Detailed implementation mode

[0032] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of 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 fall within the protection scope of the present invention.

[0033] Example 1:

[0034] Preparation of ionic covalent organic framework coupled with metal salt material ICOF-Zn(OAc)2:

[0035] (1) Preparation of ionic covalent organic framework (ICOFs):

[0036] Weigh 3.54 g (10.0 mmol) of 1,3,5-tris(bromomethyl)benzene and 2.82 g (30.0 mmol) of 4-aminopyridine, mix them evenly, and add them to 100 mL of mesitylene solvent. React at 120 °C for 5 hours under nitrogen protection. After filtering the product, wash it three times with ethyl acetate, 30 mL each time, and dry it in a vacuum drying oven at 60 °C for 10 h to obtain 1,3,5-tris(4-aminopyridine bromide)methylbenzene, and the structure is as follows:

[0037]

[0038] Weigh 0.65 g (1.4 mmol) of 1,3,5-tris(4-aminopyridine bromide)methylbenzene and 0.30 g (1.4 mmol) of 2,4,6-triformylphloroglucinol as monomers for constructing ICOFs; after mixing the two monomers evenly, add them to 15 mL of mesitylene solvent, add 8 mL of glacial acetic acid, and react at 120 °C for 72 hours under nitrogen protection. After filtering the product, wash it three times with methanol and deionized water, 30 mL each time, and place the product in a drying oven at 60 °C for 8 h to obtain the ICOFs precursor;

[0039] Ionization modification: Take 0.5 g of the obtained ICOFs precursor and disperse it in 20 mL of concentrated sulfuric acid. Stir at 80 °C for 24 hours for the sulfonation reaction. After separating the solid product, wash it three times with methanol, 30 mL each time, and dry it in a vacuum drying oven at 60 °C for 10 h to obtain an ionic covalent organic framework with sulfonic acid functional groups, denoted as ICOF-1.

[0040] (2) Loading of metal salt:

[0041] Take 0.5 g of the obtained ICOF-1 and disperse it in 80 mL of an aqueous solution containing 3 M Zn(OAc)₂. Stir at room temperature for 24 hours to carry out an ion exchange reaction, so that Zn 2+ ions are loaded into the ICOF framework; after the reaction, the solid product is filtered and washed with methanol and deionized water, three times for each, 30 mL each time; after washing, the product is placed in a vacuum drying oven and dried at 60 °C for 10 h; the ICOF-Zn(OAc)₂ composite material is obtained.

[0042] Example 2:

[0043] Preparation of ionic covalent organic framework coupled metal salt material ICOF-CoBr₂:

[0044] This example is basically the same as the preparation method of Example 1, with the difference only in step (2):

[0045] (2) Take 0.5 g of the obtained ICOF-1 and disperse it in 80 mL of an aqueous solution containing 3 M CoBr₂. Stir at room temperature for 24 hours to carry out an ion exchange reaction; after the reaction, the solid product is filtered and washed with methanol and deionized water, three times for each, 30 mL each time; after washing, the product is placed in a vacuum drying oven and dried at 60 °C for 10 h; the ICOF-CoBr₂ composite material is obtained.

[0046] Detection:

[0047] The ionic covalent organic framework coupled metal salt material catalyzes the synthesis of cyclic carbonates, and the specific general formula is as follows:

[0048] ;

[0049] where Cat. is the ionic covalent organic framework coupled metal salt material catalyst;

[0050] Add the catalyst to a 100 mL stainless steel autoclave, displace the air in the autoclave with nitrogen 3 times, and add 20 g of epoxide to the autoclave; fill a certain amount of CO₂ at room temperature, and close the intake valve of the autoclave; place the autoclave in a temperature-controlled heating furnace, first adjust the pressure of the autoclave to 1 MPa to prevent the cycloaddition reaction from being too violent at the initial reaction stage. After the temperature in the autoclave reaches the reaction temperature, keep it for about 10 min, fill CO₂ to adjust the pressure of the autoclave to the reaction pressure, and carry out the reaction. After the reaction, place the autoclave in a water bath and cool it to room temperature, slowly release the remaining gas, and take out a small amount of the reaction solution for conversion rate and selectivity analysis with an Anyipu gas chromatograph-mass spectrometer.

[0051] Referring to the above operation process, different experimental groups are set as shown in Table 1 below. Different catalysts, catalyst addition masses, epoxides, reaction temperatures, reaction pressures, and reaction times are selected in each experimental group:

[0052]

[0053] The catalyst used in Experimental Group 12 in Table 1 above is the ICOF-Zn(OAc)2 catalyst recovered after the reaction in Experimental Group 1; the catalyst used in Experimental Group 13 is the ICOF-Zn(OAc)2 catalyst recovered after the reaction in Experimental Group 12; the catalyst used in Experimental Group 14 is ICOF-1 without loading Zn salt.

[0054] And the yields and selectivities of the product carbonate esters in each experimental group are shown in Table 2 below:

[0055]

[0056] As can be seen from the above table, the ionic covalent organic framework coupled with metal salt materials can effectively ensure the yield and selectivity of carbonate esters, and the ionic covalent organic framework coupled with metal salt materials can be recycled repeatedly with little impact on its catalytic effect.

[0057] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An ionic covalent organic framework coupled with metal salt material, characterized in that, The structural formula of the ionic covalent organic framework coupled with metal salt material is as follows: ； Wherein: x, y, and z are each independently selected from any positive integers; M is any one or more of Co, Cu, Mn, Zn, and Ni; X1 is any one or more of chloride ions, bromide ions, and iodide ions; X2 is any one or more of chloride ions, bromide ions, iodide ions, acetate ions, trifluoroacetate ions, carboxylate ions, sulfate ions, bisulfate ions, and phosphate ions.

2. A preparation method of an ionic covalent organic framework coupled with a metal salt material as described in claim 1, characterized in that, The preparation method includes the following steps: S1. Using 1,3,5-tris(bromomethyl)benzene and 4-aminopyridine as reaction raw materials, and mesitylene as a solvent, reacting under the protection of an inert gas to obtain 1,3,5-tris(4-aminopyridine bromide)methylbenzene; S2. Using 1,3,5-triformylphloroglucinol and the 1,3,5-tris(4-aminopyridine bromide)methylbenzene prepared above as reaction raw materials, and mesitylene as a solvent, adding glacial acetic acid to the solvent under the protection of an inert gas to react to obtain an ionic covalent organic framework precursor; S3. Subjecting the above ionic covalent organic framework precursor to a sulfonation reaction to obtain an ionic covalent organic framework precursor with a sulfonic acid functional group; S4. Dispersing the above ionic covalent organic framework precursor with a sulfonic acid functional group in an aqueous solution of a metal salt, performing an ion exchange reaction, and then washing and drying to obtain an ionic covalent organic framework coupled with a metal salt material.

3. The preparation method according to claim 2, wherein: In the step S1, the molar ratio of 1,3,5-tris(bromomethyl)benzene to 4-aminopyridine is 1:2.0 - 5.0, and the amount of the added solvent is 10 - 20 times the total weight of the reaction raw materials, the reaction temperature is 80 - 140 °C, and the reaction time is 2 - 6 h.

4. According to the preparation method described in claim 2, in the step S2, the molar ratio of 1,3,5-triformylphloroglucinol to 1,3,5-tris(4-aminopyridine bromide)methylbenzene is 1:0.33 - 3, and the amount of added glacial acetic acid is 7 - 10 times the total weight of the reaction raw materials, and the amount of the solvent mesitylene is 10 - 20 times the total weight of the reaction raw materials; the reaction temperature is 90 - 130 °C, and the reaction time is 1 - 3 h.

5. The preparation method according to claim 2, characterized in that: In the step S3, concentrated sulfuric acid is used for the sulfonation reaction, and the amount of concentrated sulfuric acid used is 25 - 40 times the total weight of the ionic covalent organic framework precursor; and the sulfonation reaction temperature is 70 - 90 °C, and the reaction time is 24 - 36 h.

6. The preparation method according to claim 2, characterized in that: In the step S4, the concentration of the metal salt in the aqueous solution of the metal salt is 2 - 4 M, and the ion exchange reaction time is 24 - 36 h.

7. An application of the ionic covalent organic framework coupled with a metal salt material as described in claim 1 in the catalytic synthesis of carbonates.

8. The application according to claim 7, characterized in that, The application method is: using the ionic covalent organic framework coupled with a metal salt material as a catalyst to catalyze the synthesis of cyclic carbonates from epoxides and CO2.

9. The application according to claim 8, wherein: The epoxide is selected from at least one of ethylene oxide, propylene oxide, epichlorohydrin, 1,2-epoxybutane, and styrene oxide.

10. The application according to claim 8, characterized in that: The amount of the ionic covalent organic framework coupled with metal salt material added during the catalytic process is 0.5 wt.% - 3 wt.% of the mass of the epoxide; and the reaction temperature of the catalytic reaction is 80 - 150 °C; the reaction pressure is 2 - 4 MPa; the reaction time is 2 - 6 h; the reaction general formula for catalytic synthesis is shown as follows: ； Wherein R is one of a substituted or unsubstituted C1 - C15 straight-chain or branched-chain alkyl group, a substituted or unsubstituted C3 - C15 cycloalkyl group, a substituted or unsubstituted C3 - C15 heterocycloalkyl group, and a substituted or unsubstituted C6 - C15 aryl group, Cat. is the ionic covalent organic framework coupled with metal salt material as a catalyst, T represents the reaction temperature, and P represents the reaction pressure.

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