COF-CuTEP-SA polymer as well as preparation method and application thereof

Abstract

The invention relates to the technical field of porous organic polymer materials, in particular to a COF-CuTEP-SA polymer, a preparation method of the COF-CuTEP-SA polymer and application of the COF-CuTEP-SA polymer as a catalyst to catalysis of alkyl aromatic hydrocarbon oxidation reaction. The preparation method comprises the following steps: dispersing ligands 5, 10, 15, 20-tetra (4-ethynylphenyl) copper porphyrin and sulfanilic acid in an organic solvent, stirring and polymerizing under visible light to obtain a COF-CuTEP-SA polymer, and taking the structure as shown in the specification as a structural repeating unit of the COF-CuTEP-SA polymer. The COF-CuTEP-SA polymer prepared by the invention has excellent photo-thermal catalytic performance on a photocatalytic alkyl aromatic hydrocarbon oxidation reaction, and after the COF-CuTEP-SA polymer is subjected to five times of circular reaction, the catalytic yield is still 93% or above, so that the COF-CuTEP-SA polymer provided by the invention can be proved to have efficient and stable catalytic performance and can be recycled for multiple times. # imgabs0 #

Description

Technical Field

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

[0002] The information disclosed in this background technology section is only intended to enhance the 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 a person skilled in the art.

[0003] Aromatic carboxylic acids are widely used in various industries, including medicine, chemicals, food and feed additives, etc., and have penetrated into every aspect of human life, and are an indispensable class of chemicals. Most of its main raw materials, methyl aromatic hydrocarbons, are directly or indirectly derived from petroleum and are used to produce a variety of functional chemicals such as oil products, polyesters, and various chemical intermediates. The catalytic oxidation reaction of alkyl groups on aromatic rings is the most important reaction in the petrochemical industry. It is urgent to develop cleaner and more efficient catalysts and improve the efficiency of raw material and energy utilization.

[0004] In the early 20th century, large-scale industrial production of aromatic carboxylic acids appeared. The earliest process was nitric acid oxidation, which later developed into a liquid phase oxidation process using transition metal salts as catalysts. The liquid phase air oxidation processes implemented industrially in the 1940s include cyclohexane oxidation, butane oxidation, cumene oxidation, p-xylene oxidation and other liquid phase air oxidation processes. In addition, the reagent oxidation method is also a commonly used oxidation technology. It uses strong oxidants such as permanganate and dichromate to oxidize raw materials to produce corresponding carboxylic acids. However, due to the shortcomings of long process flow, low reaction efficiency, high cost and serious pollution, it does not meet the "green chemistry" requirements advocated by modern chemical industry and is gradually being eliminated. In 1958, Mid-Century developed a soluble divalent cobalt, divalent manganese and bromine salt catalyst system, and acetic acid as a solvent for the liquid phase catalytic oxidation of alkyl aromatic hydrocarbons. It was later bought out by Acomo and optimized into the existing Acomo-MC process, of which the most widely used is the oxidation of p-xylene to produce terephthalic acid. The catalyst system is highly active, so that the conversion rate of raw materials and the selectivity of target products are relatively high, but it has the problems of harsh reaction conditions and serious environmental pollution. In addition to the most widely used MC process, there are also Henkel method, air one-step catalytic oxidation method and reagent oxidation method. The Henkel method uses cadmium or zinc as a catalyst, and at a temperature of 350℃~450℃ and a pressure of 1~5MPa, phthalic anhydride is first converted into dipotassium phthalate, and dipotassium terephthalate can be obtained through transposition reaction, and then acidified to obtain terephthalic acid. This method is costly and technically complex, and has not been promoted. The air one-step catalytic oxidation method can use vanadium titanium catalysts, air as an oxygen source, and one-step selective catalytic oxidation to synthesize aromatic carboxylic acids. It has no polluting raw materials and by-products, the target product has high purity, and the production cost is low. It is an environmentally friendly and relatively economical synthesis route, but the method is complex in equipment, energy consumption is high, and production capacity is low.

[0005] Therefore, it is urgent to develop an efficient green synthesis process that can quickly and highly selectively achieve the branched oxidation of alkyl aromatic hydrocarbons to obtain aromatic carboxylic acid products and reduce the impact on the environment. Photocatalytic technology can directly use solar energy to react, with almost no consumption of other energy, so it has begun to receive more and more attention in organic synthesis, especially 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 a 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 by stirring under visible light 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 alkyl aromatic hydrocarbons to produce aromatic carboxylic acids, 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 stirred and polymerized 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, has a unique macrocyclic conjugated structure, a large rigid plane, excellent photoelectric properties, and coordination ability, etc., so that the photosensitizer can efficiently absorb visible light and can 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 aromatics. 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 aromatics. The catalyst is low in price, high in yield and purity, and 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 in the specification, 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 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 diagram 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 are 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 exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates 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 a 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 according to 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 by stirring under visible light 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 5,10,15,20-tetrakis(4-ethynylphenyl)porphyrin copper (CuTEP) in the organic solvent is 9-11 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 of 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 generate 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 in conjunction with 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), and the mixed solution was 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 an air atmosphere at room temperature for 72 h. A black crystalline solid, i.e., COF-CuTEP-SA polymer, was finally formed. The black crystalline solid was transferred to a vacuum chamber and kept at 100° C. for 12 h to obtain a COF-CuTEP-SA polymer.

[0048] The COF-CuTEP-SA polymer prepared in this example was characterized. Figure 1 This is the scanning electron microscope image of COF-CuTEP-SA polymer. Figure 2 Thermogravimetric images of COF-CuTEP-SA polymer. Figure 3 is the PXRD pattern of COF-CuTEP-SA polymer. Figure 4 This is the N2 adsorption image of COF-CuTEP-SA polymer. Figure 1 , Figure 3 and Figure 4 It can be seen from the figure that the COF-CuTEP-SA polymer prepared in this example has a porous structure. Figure 2-3 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), and the mixed solution was placed under a 250 W xenon lamp (λ>400 nm, intensity of 2.5 W cm -2 , 30 cm from the reaction vessel) and stirred, and irradiated in an air atmosphere at room temperature for 75 h. Finally, a black crystalline solid, i.e., COF-CuTEP-SA polymer, was formed. The black crystalline solid was transferred to a vacuum chamber and kept at 100° C. for 12 h to obtain a 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), and the mixed solution was placed under a 400 W xenon lamp (λ>400 nm, intensity of 2.5 W cm -2 , 30 cm from the reaction vessel) and stirred, and irradiated in an air atmosphere at room temperature for 70 h. Finally, a black crystalline solid, i.e., COF-CuTEP-SA polymer, was formed. The black crystalline solid was transferred to a vacuum chamber and kept at 100° C. for 12 h to obtain a COF-CuTEP-SA polymer.

[0055] Experimental Example 1

[0056] The COF-CuTEP-SA polymer prepared in Example 1 of the present invention is used as a catalyst in catalyzing the oxidation reaction of alkyl aromatics.

[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 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, and the reaction solution was separated to calculate the yield. The catalytic effect is shown in Table 1. Figure 5 The PXRD pattern of the catalyst after 5 cycles. Figure 5 It can be seen that after the catalyst was cycled 5 times, the COF-CuTEP-SA framework did not change. Figure 5 As can be seen from Table 1, after the catalyst was cycled three times, the yield of the product remained basically the same. After five cycles, it only showed 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 multiple cycles of COF-CuTEP-SA

[0062]

[0063] The present invention provides a COF-CuTEP-SA polymer and a preparation method and application thereof. The polymer has high crystallinity, large porosity and good chemical stability. As a catalyst, it exhibits excellent photothermal catalytic performance in the photocatalytic oxidation reaction of alkyl aromatics. The COF-CuTEP-SA polymer provided by the present invention is used as a catalyst for the oxidation of alkyl aromatics, and the yield can reach 97%. After five cycles of reaction, the polymer still maintains a catalytic yield of more than 93%, proving its efficient and stable catalytic performance, and can be recycled for multiple times.

[0064] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope 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; 2. The method for preparing the COF-CuTEP-SA polymer according to claim 1, characterized in that: include: The ligand 5,10,15,20-tetrakis(4-ethynylphenyl)porphyrin copper and p-aminobenzenesulfonic acid are dispersed in an organic solvent and polymerized by stirring under visible light to obtain a COF-CuTEP-SA polymer.

3. The preparation method according to claim 2, characterized in that: 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, preferably 1:

2.

4. The preparation method according to claim 2, characterized in that: The organic solvent includes N,N-dimethylformamide; Alternatively, the concentration of the ligand 5,10,15,20-tetrakis(4-ethynylphenyl)porphyrin copper in the organic solvent is 9 to 11 mmol / L, preferably 10 mmol / L.

5. The preparation method according to claim 2, characterized in that: A xenon lamp is used to simulate visible light, and the power of the xenon lamp is 250-400w, preferably 300w; Alternatively, the time for stirring polymerization under visible light is 70 to 75 hours, preferably 72 hours.

6. Use of the COF-CuTEP-SA polymer according to claim 1 and / or the COF-CuTEP-SA polymer prepared by the preparation method according to any one of claims 2 to 5 as a catalyst.

7. The use according to claim 6, characterized in that The application includes: catalyzing the oxidation of alkyl aromatics to generate aromatic carboxylic acids under visible light; Preferably, a xenon lamp is used to simulate visible light, and the power of the xenon lamp is 250-400w, preferably 300w.

8. A method for oxidizing alkyl aromatic hydrocarbons to produce aromatic carboxylic acids, characterized in that: include: Alkyl aromatic hydrocarbons are dispersed in a solvent, the COF-CuTEP-SA polymer according to claim 1 and / or the COF-CuTEP-SA polymer prepared by the preparation method according to any one of claims 2 to 5 are added as a catalyst, and aromatic carboxylic acid is obtained by stirring under visible light.

9. The method according to claim 8, characterized in that A xenon lamp is used to simulate visible light, and the power of the xenon lamp is 250-400w, preferably 300w.

10. The method according to claim 8, characterized in that The solvent includes deionized water; Alternatively, the molar ratio of the alkyl aromatic hydrocarbon to the COF-CuTEP-SA polymer is 15 to 20:1, preferably 16.7:1.

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