A COF-CuTEP-SA polymer and its preparation method and application

Abstract

The present invention relates to the technical field of porous organic polymer materials, and in particular to a COF-CuTEP-SA polymer, a preparation method thereof, and its use as a catalyst in catalyzing the oxidation reaction of alkyl aromatic hydrocarbons. The ligand 5,10,15,20-tetrakis(4-ethynylphenyl)porphyrin copper and p-aminobenzenesulfonic acid are dispersed in an organic solvent, stirred and polymerized under visible light to obtain a COF-CuTEP-SA polymer, wherein the COF-CuTEP-SA polymer has the following structure as a structural repeating unit. The COF-CuTEP-SA polymer prepared by the present invention has excellent photothermal catalytic performance for the photocatalytic oxidation reaction of alkyl aromatic hydrocarbons. After the COF-CuTEP-SA polymer is subjected to five cycle reactions, the catalytic yield is still maintained at 93% or above. Therefore, it can be proved that the COF-CuTEP-SA polymer provided by the present invention has efficient and stable catalytic performance and can be recycled multiple times. #imgabs0#

Description

Technical Field

[0001] The present invention relates to the technical field of porous organic polymer materials, and in particular to a COF-CuTEP-SA polymer, a preparation method thereof, and application of the polymer as a catalyst in catalyzing alkyl aromatic hydrocarbon oxidation reactions. Background Art

[0002] The information disclosed in this background technology section is only intended to enhance understanding of the overall background of the invention and should not necessarily be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to those skilled in the art.

[0003] Aromatic carboxylic acids are widely used in various industries, including pharmaceuticals, chemicals, and food and feed additives. They permeate every aspect of human life, making them indispensable chemicals. Their primary raw material, methyl aromatic hydrocarbons, is primarily derived directly or indirectly from petroleum and is used to produce a variety of functional chemicals, including oil products, polyesters, and various chemical intermediates. The catalytic oxidation of alkyl groups on aromatic rings is a crucial reaction in the petrochemical industry, necessitating the development of cleaner and more efficient catalysts to improve raw material and energy efficiency.

[0004] Large-scale industrial production of aromatic carboxylic acids emerged in the early 20th century. The earliest process employed nitric acid oxidation, which later evolved into liquid-phase oxidation processes catalyzed by transition metal salts. Liquid-phase air oxidation processes implemented industrially in the 1940s included cyclohexane, butane, cumene, and p-xylene. Reagent oxidation is also a commonly used oxidation technique, utilizing strong oxidants such as permanganate and dichromate to oxidize the raw materials and produce the corresponding carboxylic acids. However, due to its lengthy process, low reaction efficiency, high cost, and significant pollution, it does not meet the "green chemistry" standards advocated by modern chemical industry and is gradually being phased out. In 1958, Mid-Century Corporation developed a liquid-phase catalytic oxidation technology for alkyl aromatic hydrocarbons using a soluble divalent cobalt, divalent manganese, and bromide catalyst system and acetic acid as the solvent. This technology was later acquired by Acomo and optimized into the current Acomo-MC process, the most widely used of which is the oxidation of p-xylene to produce terephthalic acid. This catalyst system is highly active, resulting in relatively high raw material conversion rates and selectivity for the target product. However, it suffers from harsh reaction conditions and severe environmental pollution. In addition to the currently most widely used MC process, there are also the Henkel process, the air one-step catalytic oxidation process, and the reagent oxidation process. The Henkel process uses cadmium or zinc as a catalyst. Under conditions of 350°C to 450°C and 1-5 MPa, phthalic anhydride is first converted into dipotassium phthalate. A metathesis reaction produces dipotassium terephthalate, which is then acidified to produce terephthalic acid. This method is costly and technically complex, and has not been widely adopted. The air one-step catalytic oxidation process uses a vanadium-titanium catalyst and air as the oxygen source to selectively oxidize aromatic carboxylic acids in a single step. This process produces no polluting raw materials or byproducts, produces high purity target products, and has low production costs. It is an environmentally friendly and relatively economical synthetic route, but it requires complex equipment, high energy consumption, and low production capacity.

[0005] Therefore, there is an urgent need to develop an efficient, green synthesis process that can rapidly and selectively oxidize the side chains of alkyl aromatic hydrocarbons to aromatic carboxylic acid products while minimizing environmental impact. Photocatalytic technology can directly utilize solar energy to carry out reactions, consuming virtually no other energy. Therefore, it is gaining increasing attention in organic synthesis, particularly in photocatalytic selective oxidation. Summary of the Invention

[0006] In order to overcome the above problems, the present invention provides a COF-CuTEP-SA polymer and a preparation method and application thereof.

[0007] In order to achieve the above technical objectives, the present invention adopts the following technical solutions:

[0008] In the first aspect of the present invention, a COF-CuTEP-SA polymer is provided, wherein the COF-CuTEP-SA polymer has the structure represented by formula (I) as a structural repeating unit;

[0009]

[0010] The second aspect of the present invention provides a method for preparing the COF-CuTEP-SA polymer described in the first aspect, comprising:

[0011] The ligand 5,10,15,20-tetrakis(4-ethynylphenyl)porphyrin copper (CuTEP) and p-aminobenzenesulfonic acid (SA) were dispersed in an organic solvent and polymerized under visible light under stirring to obtain COF-CuTEP-SA polymer.

[0012] The third aspect of the present invention provides use of the COF-CuTEP-SA polymer described in the first aspect as a catalyst.

[0013] A fourth aspect of the present invention provides a method for oxidizing an alkyl aromatic hydrocarbon to produce an aromatic carboxylic acid, comprising:

[0014] Alkyl aromatic hydrocarbons are dispersed in a solvent, the COF-CuTEP-SA polymer described in the first aspect is added as a catalyst, and the aromatic carboxylic acid is obtained by stirring under visible light.

[0015] The beneficial effects of the present invention are:

[0016] (1) In the present invention, the ligand 5,10,15,20-tetrakis(4-ethynylphenyl)porphyrin copper (CuTEP) and p-aminobenzenesulfonic acid (SA) are dispersed in an organic solvent and polymerized by stirring under visible light to obtain a COF-CuTEP-SA polymer. The COF-CuTEP-SA polymer prepared by the present invention has the properties of high crystallinity, large porosity, and good chemical stability, and therefore has the potential to be used as a catalyst. The COF-CuTEP-SA polymer contains a porphyrin motif and has a unique macrocyclic conjugated structure, a large rigid plane, excellent photoelectric properties and coordination ability, etc., which enables this photosensitizer to efficiently absorb visible light and effectively capture electrons generated by light excitation, thereby showing good photocatalytic efficiency.

[0017] (2) The COF-CuTEP-SA polymer prepared by the present invention has excellent photothermal catalytic performance for the photocatalytic oxidation reaction of alkyl aromatic hydrocarbons. After the COF-CuTEP-SA polymer is subjected to five cycles of reaction, the catalytic yield is still maintained at 93% or above. Therefore, it can be proved that the COF-CuTEP-SA polymer provided by the present invention has efficient and stable catalytic performance and can be recycled multiple times.

[0018] (3) The present invention uses the prepared polymer COF-CuTEP-SA polymer as a catalyst for the oxidation reaction of alkyl aromatic hydrocarbons. The catalyst is low in price, has high yield and purity, is easy to separate, no special, toxic or harmful reagents are used during the experiment, and the reaction conditions are mild. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The accompanying drawings, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0020] Figure 1 This is a scanning electron microscope image of COF-CuTEP-SA prepared in Example 1 of the present invention;

[0021] Figure 2 This is the thermogravimetric diagram of COF-CuTEP-SA prepared in Example 1 of the present invention;

[0022] Figure 3 1 are the experimental and simulated PXRD patterns of COF-CuTEP-SA prepared in Example 1 of the present invention;

[0023] Figure 4 This is the N2 adsorption graph of COF-CuTEP-SA prepared in Example 1 of the present invention;

[0024] Figure 5 This is the PXRD pattern of the COF-CuTEP-SA prepared in Example 1 of the present invention after catalysis for 5 times. DETAILED DESCRIPTION

[0025] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0026] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0027] A first typical embodiment of the present invention provides a COF-CuTEP-SA polymer, wherein the COF-CuTEP-SA polymer has the structure represented by formula (I) as a structural repeating unit;

[0028]

[0029] A second typical embodiment of the present invention provides a method for preparing the COF-CuTEP-SA polymer described in the first aspect, comprising:

[0030] The ligand 5,10,15,20-tetrakis(4-ethynylphenyl)porphyrin copper (CuTEP) and p-aminobenzenesulfonic acid (SA) were dispersed in an organic solvent and polymerized under visible light under stirring to obtain COF-CuTEP-SA polymer.

[0031] In one or more embodiments, the molar ratio of the ligand 5,10,15,20-tetrakis(4-ethynylphenyl)porphyrin copper (CuTEP) to p-aminobenzenesulfonic acid (SA) is 1:1.8-2.2, preferably 1:2.

[0032] In one or more embodiments, the organic solvent includes N,N-dimethylformamide (DMF).

[0033] In one or more embodiments, the concentration of the ligand copper 5,10,15,20-tetrakis(4-ethynylphenyl)porphyrin (CuTEP) in the organic solvent is 9 to 11 mmol / L, preferably 10 mmol / L.

[0034] In one or more embodiments, a xenon lamp is used to simulate visible light, and the power of the xenon lamp is 250-400W, preferably 300W.

[0035] In one or more embodiments, the time for stirring polymerization under visible light is 70 to 75 hours, preferably 72 hours.

[0036] A third typical embodiment of the present invention provides use of the COF-CuTEP-SA polymer described in the first aspect as a catalyst.

[0037] In one or more embodiments, the application includes: catalyzing the oxidation of alkyl aromatic hydrocarbons to produce aromatic carboxylic acids under visible light.

[0038] Preferably, a xenon lamp is used to simulate visible light, and the power of the xenon lamp is 250-400W, preferably 300W.

[0039] A fourth typical embodiment of the present invention provides a method for oxidizing alkyl aromatic hydrocarbons to produce aromatic carboxylic acids, comprising:

[0040] Alkyl aromatic hydrocarbons are dispersed in a solvent, the COF-CuTEP-SA polymer described in the first aspect is added as a catalyst, and the aromatic carboxylic acid is obtained by stirring under visible light.

[0041] In one or more embodiments, a xenon lamp is used to simulate visible light, and the power of the xenon lamp is 250-400W, preferably 300W.

[0042] In one or more embodiments, the solvent includes deionized water.

[0043] In one or more embodiments, the molar ratio of the alkyl aromatic hydrocarbon to the COF-CuTEP-SA polymer is 15 to 20:1, preferably 16.7:1.

[0044] In order to enable those skilled in the art to more clearly understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0045] Example 1

[0046] Preparation of COF-CuTEP-SA polymer:

[0047] The ligand 5,10,15,20-tetrakis(4-ethynylphenyl)porphyrin copper (CuTEP) (0.02 mmol, 16.0 mg) and p-aminobenzenesulfonic acid (SA) (0.04 mmol, 6.9 mg) were dispersed in N,N-dimethylformamide (DMF) (2 mL). The mixed solution was then placed under a 300 W xenon lamp (λ>400 nm, intensity of 2.5 W cm -2 The mixture was stirred at 30 cm from the reaction vessel and irradiated in air at room temperature for 72 h. A black crystalline solid, i.e., COF-CuTEP-SA polymer, was formed. The black crystalline solid was transferred to a vacuum chamber and maintained at 100°C for 12 h to obtain COF-CuTEP-SA polymer.

[0048] The COF-CuTEP-SA polymer prepared in this example was characterized. Figure 1 is the scanning electron microscope image of COF-CuTEP-SA polymer. Figure 2 Thermogravimetric image of COF-CuTEP-SA polymer. Figure 3 is the PXRD pattern of COF-CuTEP-SA polymer, Figure 4 N2 adsorption image of COF-CuTEP-SA polymer. Figure 1 、 Figure 3 and Figure 4 It can be seen from the above that the COF-CuTEP-SA polymer prepared in this embodiment has a porous structure. Figures 2 and 3 It can be seen that the COF-CuTEP-SA polymer is a crystalline porous material with high thermal stability.

[0049] Example 2

[0050] Preparation of COF-CuTEP-SA polymer:

[0051] The ligand 5,10,15,20-tetrakis(4-ethynylphenyl)porphyrin copper (CuTEP) (0.018 mmol, 14.4 mg) and p-aminobenzenesulfonic acid (SA) (0.04 mmol, 6.9 mg) were dispersed in N,N-dimethylformamide (DMF) (2 mL). The mixed solution was then placed under a 250 W xenon lamp (λ>400 nm, intensity of 2.5 W cm -2 The mixture was stirred at 30 cm from the reaction vessel and irradiated in air at room temperature for 75 h. A black crystalline solid, i.e., COF-CuTEP-SA polymer, was formed. The black crystalline solid was transferred to a vacuum chamber and maintained at 100°C for 12 h to obtain COF-CuTEP-SA polymer.

[0052] Example 3

[0053] Preparation of COF-CuTEP-SA polymer:

[0054] The ligand 5,10,15,20-tetrakis(4-ethynylphenyl)porphyrin copper (CuTEP) (0.022 mmol, 17.6 mg) and p-aminobenzenesulfonic acid (SA) (0.04 mmol, 6.9 mg) were dispersed in N,N-dimethylformamide (DMF) (2 mL). The mixed solution was then placed under a 400 W xenon lamp (λ>400 nm, intensity of 2.5 W cm -2 The mixture was stirred at 30 cm from the reaction vessel and irradiated in air at room temperature for 70 h. A black crystalline solid, i.e., COF-CuTEP-SA polymer, was formed. The black crystalline solid was transferred to a vacuum chamber and maintained at 100°C for 12 h to obtain COF-CuTEP-SA polymer.

[0055] Experimental Example 1

[0056] The COF-CuTEP-SA polymer prepared in Example 1 of the present invention was used as a catalyst to catalyze the oxidation reaction of alkyl aromatic hydrocarbons.

[0057] The preparation process is as follows: toluene (0.5 mmol) and COF-CuTEP-SA (0.03 mmol, 26.0 mg) are placed in a flask, water (2.5 mL) is added, and the mixed solution is placed under a 300 W xenon lamp (λ>400 nm, intensity of 2.5 W cm -2 , 30 cm away from the reaction vessel) and stirred, and irradiated in an air atmosphere at room temperature for 8 h to obtain the corresponding product.

[0058] The specific reaction equation is as follows:

[0059]

[0060] The reaction was tracked by TLC. After the reaction was completed, the catalyst was recovered by centrifugation and directly put into the next cycle reaction. According to the above conditions, the catalyst was used for 5 cycles. The reaction solution was separated and the yield was calculated. The catalytic effect is shown in Table 1. Figure 5 The PXRD pattern of the catalyst after 5 cycles is shown in Figure 2. Figure 5 It can be seen that after 5 cycles of the catalyst, the COF-CuTEP-SA framework has not changed. Figure 5 As can be seen from Table 1, after the catalyst was recycled three times, the yield of the product remained basically the same. After five cycles, it showed only a slight downward trend, reflecting the excellent stability of the catalyst. It can be reused more than five times, which can significantly improve the utilization rate of the catalyst and reduce production costs.

[0061] Table 1 Catalytic effect of COF-CuTEP-SA multiple cycle reactions

[0062]

[0063] The present invention provides a COF-CuTEP-SA polymer, its preparation method, and its application. The polymer has high crystallinity, large porosity, and good chemical stability. As a catalyst, it exhibits excellent photothermal catalytic performance in the photocatalytic oxidation of alkyl aromatic hydrocarbons. The COF-CuTEP-SA polymer provided by the present invention can be used as a catalyst for the oxidation of alkyl aromatic hydrocarbons, with a yield of up to 97%. After five cycles of reaction, the polymer still maintained a catalytic yield of over 93%, demonstrating its efficient and stable catalytic performance and multiple recycling capabilities.

[0064] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A COF-CuTEP-SA polymer, characterized in that The COF-CuTEP-SA polymer has the structure shown in formula (I) as a structural repeating unit; Formula (I).

2. The method for preparing the COF-CuTEP-SA polymer according to claim 1, wherein include: The ligand 5,10,15,20-tetrakis(4-ethynylphenyl)porphyrin copper and p-aminobenzenesulfonic acid were dispersed in an organic solvent and stirred and polymerized under visible light to obtain COF-CuTEP-SA polymer.

3. The preparation method according to claim 2, wherein The molar ratio of the ligand 5,10,15,20-tetrakis(4-ethynylphenyl)porphyrin copper to p-aminobenzenesulfonic acid is 1:1.8~2.

2.

4. The preparation method according to claim 3, wherein The molar ratio of the ligand 5,10,15,20-tetrakis(4-ethynylphenyl)porphyrin copper and p-aminobenzenesulfonic acid is 1:

2.

5. The preparation method according to claim 2, wherein The organic solvent includes N,N-dimethylformamide.

6. The preparation method according to claim 2, wherein The concentration of the ligand 5,10,15,20-tetrakis(4-ethynylphenyl)porphyrin copper in the organic solvent is 9-11 mmol / L.

7. The preparation method according to claim 6, wherein The concentration of the ligand 5,10,15,20-tetrakis(4-ethynylphenyl)porphyrin copper in the organic solvent was 10 mmol / L.

8. The preparation method according to claim 2, wherein A xenon lamp is used to simulate visible light, and the power of the xenon lamp is 250~400w.

9. The preparation method according to claim 8, wherein The power of the xenon lamp is 300 W.

10. The preparation method according to claim 2, wherein The stirring polymerization time under visible light is 70~75h.

11. The preparation method according to claim 10, characterized in that The polymerization time under visible light stirring was 72 h.

12. Use of the COF-CuTEP-SA polymer according to claim 1 or the COF-CuTEP-SA polymer prepared by the preparation method according to any one of claims 2 to 11 as a catalyst.

13. The use according to claim 12, characterized in that The application includes: catalyzing the oxidation of alkyl aromatic hydrocarbons to generate aromatic carboxylic acids under visible light.

14. The use according to claim 13, characterized in that A xenon lamp is used to simulate visible light, and the power of the xenon lamp is 250~400w.

15. The use according to claim 14, characterized in that The power of the xenon lamp is 300 W.

16. A method for oxidizing alkyl aromatic hydrocarbons to produce aromatic carboxylic acids, characterized in that: include: Alkyl aromatic hydrocarbon is dispersed in a solvent, the COF-CuTEP-SA polymer according to claim 1 or the COF-CuTEP-SA polymer prepared by the preparation method according to any one of claims 2 to 11 is added as a catalyst, and the aromatic carboxylic acid is obtained by stirring under visible light.

17. The method according to claim 16, wherein A xenon lamp is used to simulate visible light, and the power of the xenon lamp is 250~400w.

18. The method according to claim 17, wherein The power of the xenon lamp is 300 W.

19. The method according to claim 16, wherein The solvent includes deionized water.

20. The method of claim 16, wherein: The molar ratio of alkyl aromatic hydrocarbon to COF-CuTEP-SA polymer is 15~20:

1.

21. The method according to claim 20, wherein The molar ratio of alkyl aromatic hydrocarbon to COF-CuTEP-SA polymer is 16.7:1.

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