Preparation method of tetrazinyl three-dimensional covalent organic framework with dual interpenetrating structure and application of tetrazinyl three-dimensional covalent organic framework in photocatalytic synthesis of urea

Abstract

The invention discloses a preparation method of a tetrazinyl three-dimensional covalent organic framework with a dual interpenetrating structure, which comprises the following steps: 1, adding 5, 5 '-(1, 2, 4, 5-tetrazin-3, 6-diyl) bisbenzene-1, 3-diamine and 1, 3, 5-tri (p-formylphenyl) benzene into a high-pressure-resistant glass container containing a mixed solvent of mesitylene and dioxane, and adding an acetic acid solution; 2, filling nitrogen into the container, degassing and sealing; 3, placing the sealed container in a drying oven, heating, and preserving heat; 4, the reactants are cooled, filtered, washed, precipitated and dried in vacuum, the dual-interpenetrating tetraazinyl three-dimensional covalent organic framework with an ffc topological structure is obtained, the structural formula of the tetraazinyl three-dimensional covalent organic framework is # imgabs0 #, and the yield is about 60%; the tetraazinyl three-dimensional covalent organic framework material with the constructed dual interpenetrating structure is obtained through an aldehyde amine condensation reaction, and the tetraazinyl three-dimensional covalent organic framework material with the dual interpenetrating structure is obtained; the preparation method is simple to operate, the photocatalytic performance is excellent, and recycling of the catalyst is facilitated; the method is suitable for urea production.

Description

Technical Field

[0001] The invention belongs to the technical field of material preparation and photocatalysis, and particularly relates to a preparation method of a tetrazine-based three-dimensional covalent organic framework with a double interpenetrating structure and an application of the same in photocatalytic synthesis of urea. Background Art

[0002] Urea, as an important nitrogen fertilizer, is an indispensable raw material in agricultural production. In addition, urea has a wide range of non-agricultural applications and can be widely used in the preparation of products such as medicines and dyes. The industrial synthesis of urea currently adopts the Bosch-Meiser process, which requires high temperature and high pressure reaction conditions, consumes a lot of energy and emits a large amount of greenhouse gas CO2. Therefore, it is particularly important to synthesize urea using an energy-saving and environmentally friendly route.

[0003] Covalent organic framework materials are crystalline porous materials with precise topological structures and clear pore size distribution linked by covalent bonds. COFs materials are mostly composed of some lighter chemical elements (C, N, B, O, Si) and have many advantages such as excellent pore properties, large specific surface area, good stability and easy functionalization. In recent years, they have been widely used in gas storage and separation, optoelectronic materials, catalysis, drug release and energy, and have shown excellent application prospects. Therefore, they have attracted extensive attention and research from materials scientists and chemists, and have become another new type of functional material after metal-organic frameworks (MOFs). Compared with traditional inorganic porous materials linked by non-covalent bonds, COFs are linked by covalent bonds. While the pore properties of the material are maintained, the molecular grid structure is more stable. Due to the diversity of molecular structural units and synthetic methods that constitute COFs, not only the final COFs materials have rich structural compositions and controllable pore properties, but more importantly, they can also introduce functional building units purposefully, so that the final materials have corresponding functional properties.

[0004] According to the characteristics of covalent organic framework materials, the present invention develops a tetrazine-based three-dimensional covalent organic framework with a double interpenetrating structure and linked by imine bonds, which can catalyze NH3 and CO2 to generate urea at room temperature and pressure. Summary of the invention

[0005] The purpose of the present invention is to provide a method for preparing a tetrazine-based three-dimensional covalent organic framework with a double interpenetrating structure and its application in photocatalytic synthesis of urea, aiming to solve the existing energy crisis and / or environmental problems of global warming.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0007] A method for preparing a tetrazine-based three-dimensional covalent organic framework having a double interpenetrating structure comprises the following steps:

[0008] Step 1: Add 5,5'-(1,2,4,5-tetrazine-3,6-diyl)biphenyl-1,3-diamine and 1,3,5-tri(p-formylphenyl)benzene in a molar ratio of 3:4 into a high pressure glass container containing a mixed solvent of mesitylene and dioxane, and add acetic acid solution;

[0009] Step 2: nitrogen is poured into the high pressure glass container, and the container is degassed and then evacuated to a vacuum state and sealed;

[0010] Step 3: Place the sealed glass container in an oven to heat and keep it warm;

[0011] Step 4: The reactants are cooled to 25 degrees Celsius, filtered, and the precipitate is washed with tetrahydrofuran and acetone, respectively, and vacuum dried to obtain a doubly interpenetrating tetrazine-based three-dimensional covalent organic framework having an ffc topological structure. The structural formula of the tetrazine-based three-dimensional covalent organic framework is The yield is about 60%.

[0012] Furthermore, in step 1, the total mass of 5,5'-(1,2,4,5-tetrazine-3,6-diyl)biphenyl-1,3-diamine and 1,3,5-tri(p-formylphenyl)benzene contained in each milliliter of the mixed solvent is 15-35 mg.

[0013] Furthermore, the degassing treatment in step 2 is performed at least 3 times.

[0014] Further, in step three, the mixture is heated to 120 degrees Celsius and kept warm for 72 hours.

[0015] Furthermore, in step 4, the drying temperature is 60 degrees Celsius, and the drying is performed until the detergent is completely evaporated.

[0016] A tetrazine-based three-dimensional covalent organic framework with a double interpenetrating structure is used in the photocatalytic synthesis of urea. The tetrazine-based three-dimensional covalent organic framework with a double interpenetrating structure is a double interpenetrating tetrazine-based three-dimensional covalent organic framework with an FFC topological structure prepared according to the preparation method of a tetrazine-based three-dimensional covalent organic framework with a double interpenetrating structure according to any one of claims 1 to 5.

[0017] Furthermore, in a photocatalytic intermittent reactor, the tetrazine-based three-dimensional covalent organic framework with a double interpenetrating structure is used as a photocatalyst to obtain urea through a photocatalytic coupling reaction of NH3 and CO2.

[0018] Furthermore, the photocatalytic temperature is 25 degrees Celsius; the catalytic reaction is carried out under light.

[0019] Furthermore, water is used as a solvent in the reaction system.

[0020] Furthermore, under light, the rate of urea production in an NH3 / CO2 atmosphere was 532 μmol g -1 h -1 .

[0021] Due to the adoption of the above structure, the present invention has at least one of the following technical advances compared with the prior art:

[0022] 1. The tetrazine-based three-dimensional covalent organic framework material with a double interpenetrating structure constructed by the present invention is obtained by the aldehyde-amine condensation reaction of 5,5'-(1,2,4,5-tetrazine-3,6-diyl)diphenyl-1,3-diamine and 1,3,5-tri-p-(formylphenyl)benzene. Under light drive, it has excellent performance in photocatalytic coupling of NH3 and CO2 to generate urea.

[0023] 2. The method for preparing the tetrazine-based three-dimensional covalent organic framework with a double interpenetrating structure provided by the present invention is simple to operate, has excellent photocatalytic performance and is conducive to the recycling of the catalyst, and has excellent practical commercial application potential.

[0024] 3. The catalytic reaction system of the tetrazine-based three-dimensional covalent organic framework material with a double interpenetrating structure of the present invention is pure water, and the reaction system has the characteristics of being green, pollution-free and low-cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings are used to provide further understanding of the present invention and constitute a part of the specification. They are used to explain the present invention together with the embodiments of the present invention and do not constitute a limitation of the present invention.

[0026] In the attached picture:

[0027] Figure 1 Schematic diagram of the molecular structure of the tetrazine-based three-dimensional covalent organic framework of the present invention;

[0028] Figure 2 Schematic diagram of the double interpenetrating structure of the tetrazine-based three-dimensional covalent organic framework of the present invention;

[0029] Figure 3 A powder X-ray diffraction spectrum of the tetrazine-based three-dimensional covalent organic framework with a double interpenetrating structure according to the present invention;

[0030] Figure 4 A high-resolution transmission electron microscope characterization image of the tetrazine-based three-dimensional covalent organic framework of the double interpenetrating structure of the present invention;

[0031] Figure 5 Schematic diagram of the molecular structure of the pyrazine-based three-dimensional covalent organic framework of the present invention;

[0032] Figure 6A powder X-ray diffraction spectrum of the pyrazine-based three-dimensional covalent organic framework with a double interpenetrating structure according to the present invention;

[0033] Figure 7 It is a schematic diagram of the yield of urea produced by the tetrazine-based three-dimensional covalent organic framework and the pyrazine-based three-dimensional covalent organic framework of the present invention;

[0034] Figure 8 Schematic diagram of the stability of the tetrazine-based three-dimensional covalent organic framework catalyzing the production of urea. DETAILED DESCRIPTION

[0035] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0036] Example Preparation method of a tetrazine-based three-dimensional covalent organic framework with a double interpenetrating structure and its application in photocatalytic synthesis of urea

[0037] This embodiment 1 discloses a method for preparing a tetrazine-based three-dimensional covalent organic framework having a double interpenetrating structure, such as Figure 1 As shown, the doubly interpenetrating tetrazine-based three-dimensional covalent organic framework (3D-TBBD-COF) is mainly synthesized by 5,5'-(1,2,4,5-tetrazine-3,6-diyl)biphenyl-1,3-diamine and 1,3,5-tri(p-formylphenyl)benzene through the Schiff base reaction of aldehyde amine condensation, and the two are linked by covalent bonds. 5,5'-(1,2,4,5-tetrazine-3,6-diyl)biphenyl-1,3-diamine is used as a new connecting unit for the synthesis: Step 1: 3,5-diaminobenzonitrile, hydrazine hydrate and sulfur powder are dissolved in ethanol; Step 2: The obtained solution is heated at 90 Heat and stir at 400 °C for 10 hours. After the reaction is completed, wash with ethanol and acetone. Step 3: Dry in a vacuum oven at 60 °C to obtain a bright yellow powder. Step 4: Disperse the bright yellow powder in dry dimethyl sulfoxide and introduce oxygen. Step 5: Add 150 ml of distilled water to the oxidized compound to precipitate a bright red product, which is dispersed in a H2O2 solution. The red product 5,5'-(1,2,4,5-tetrazine-3,6-diyl)diphenyl-1,3-diamine is separated by centrifugation. 1,3,5-Tris(p-formylphenyl)benzene is an existing product and can be purchased on the market.

[0038] A method for preparing a tetrazine-based three-dimensional covalent organic framework having a double interpenetrating structure, which is specifically prepared by the following method:

[0039] Step 1, adding 5,5'-(1,2,4,5-tetrazine-3,6-diyl)biphenyl-1,3-diamine and 1,3,5-tri(p-formylphenyl)benzene in a molar ratio of 3:4 to a mixed solvent of mesitylene and dioxane in a long glass tube, wherein the total mass of 5,5'-(1,2,4,5-tetrazine-3,6-diyl)biphenyl-1,3-diamine and 1,3,5-tri(p-formylphenyl)benzene per milliliter of the mixed solvent is 15-35 mg, and adding acetic acid solution to catalyze the reaction to produce;

[0040] Step 2: nitrogen is flushed into the long glass tube, and degassing treatment is carried out by three freeze-evacuation-thaw cycles, and the tube is evacuated into a vacuum state and sealed with a flame;

[0041] Step 3: Place the sealed long glass tube in an oven, heat to 120 degrees Celsius and keep it for 72 hours;

[0042] Step 4: The reactant was cooled to 25 degrees Celsius, the precipitated solid was collected by filtration, and washed with tetrahydrofuran (2×20 ml) and acetone (3×20 ml). The obtained solid was vacuum dried at 60 degrees Celsius until the detergent was completely evaporated to obtain a doubly interpenetrating tetrazine-based three-dimensional covalent organic framework material with a ffc topological structure. The yield was about 60%. The structural formula of the tetrazine-based three-dimensional covalent organic framework is

[0043] The structure of the tetrazine-based three-dimensional covalent organic framework with double interpenetrating structure prepared above was analyzed, and the following results were obtained: Figure 1-Figure 4 The results shown are:

[0044] like Figure 1 As shown, the tetrazine-based three-dimensional covalent organic framework is composed of 5,5'-(1,2,4,5-tetrazine-3,6-diyl)biphenyl-1,3-diamine and 1,3,5-tri(p-formylphenyl)benzene.

[0045] Depend on Figure 2 It can be seen that the tetrazine-based three-dimensional covalent organic framework has an obvious double interpenetrating structure.

[0046] Depend on Figure 3 It can be seen that the tetrazine-based three-dimensional covalent organic framework with a double interpenetrating structure has a sharp diffraction peak.

[0047] Depend on Figure 4 It can be seen that the tetrazine-based three-dimensional covalent organic framework with a doubly interpenetrating structure has obvious lattice fringes, indicating that it is a highly crystalline framework material.

[0048] Control Example 1 discloses a method for preparing a pyrazine-based three-dimensional covalent organic framework having a double interpenetrating structure, which is used to compare and study the advantages of a tetrazine-based three-dimensional covalent organic framework having a double interpenetrating structure in the photocatalytic synthesis of urea. Figure 5 As shown, the doubly interpenetrating pyrazine-based three-dimensional covalent organic framework (3D-PDDP-COF) is mainly synthesized by using 5,5'-(pyrazine-3,6-diyl)diisophthalaldehyde and 1,3,5-tris(4-aminophenyl)dimethylbenzene as new connecting units: Step 1: 3,5-diformylphenylboronic acid, potassium carbonate and tetrakistriphenylphosphine palladium are dissolved in a mixed solution of dioxane and water under argon environment; Step 2: The obtained solution is heated and stirred at 110°C for 24 hours. After the reaction is completed, the solvent is evaporated under reduced pressure; Step 3: The product is extracted with ethyl acetate and water, and then evaporated to dryness; Step 4: The crude product is purified by silica gel flash column chromatography to obtain pure 5,5'-(pyrazine-3,6-diyl)diisophthalaldehyde; 1,3,5-tris(4-aminophenyl)benzene is an existing product and can be purchased on the market.

[0049] A method for preparing a pyrazine-based three-dimensional covalent organic framework with a double interpenetrating structure, which is specifically prepared by the following method:

[0050] Step 1, adding 5,5'-(pyrazine-3,6-diyl) diisophthalaldehyde and 1,3,5-tris(4-aminophenyl)benzene in a molar ratio of 3:4 to a mixed solvent of mesitylene and dioxane in a long glass tube, wherein the total mass of 5,5'-(pyrazine-3,6-diyl) diisophthalaldehyde and 1,3,5-tris(4-aminophenyl)benzene per milliliter of the mixed solvent is 15-35 mg, and adding acetic acid solution to catalyze the reaction to produce;

[0051] Step 2: nitrogen is flushed into the long glass tube, and degassing treatment is carried out by three freeze-evacuation-thaw cycles, and the tube is evacuated into a vacuum state and sealed with a flame;

[0052] Step 3: Place the sealed long glass tube in an oven, heat to 120 degrees Celsius and keep it for 72 hours;

[0053] Step 4: The reactant is cooled to 25 degrees Celsius, the precipitated solid is collected by filtration, and washed with tetrahydrofuran (2×20 ml) and acetone (3×20 ml). The obtained solid is vacuum dried at 60 degrees Celsius until the detergent is completely evaporated to obtain a pyrazinyl three-dimensional covalent organic framework material having the same structure as the tetrazine-based three-dimensional covalent organic framework, with a yield of about 70%. The structural formula of the pyrazinyl three-dimensional covalent organic framework is

[0054] The structure of the pyrazine-based three-dimensional covalent organic framework with double interpenetrating structure prepared above was analyzed, and the following results were obtained: Figure 5-Figure 6 The results shown are:

[0055] like Figure 5 As shown, the pyrazine-based three-dimensional covalent organic framework is composed of 5,5'-(pyrazine-3,6-diyl)xylene dicarboxaldehyde and 1,3,5-tris(4-aminophenyl)benzene.

[0056] like Figure 6 As shown, the pyrazine-based three-dimensional covalent organic framework with a double interpenetrating structure also has sharp diffraction peaks.

[0057] Example 2 Application of a tetrazine-based three-dimensional covalent organic framework having a double interpenetrating structure in photocatalytic synthesis of urea specifically comprises the following steps:

[0058] The doubly interpenetrating tetrazine-based three-dimensional covalent organic framework material is used as the catalyst, and water is used as the solvent of the reaction system. Under light, the temperature of the space where the photocatalytic intermittent reactor is located is maintained at 25 degrees Celsius. Before the catalytic reaction begins, NH3 and CO2 are introduced into the reactor to remove other gases. After the reaction, the liquid product produced in the experiment is detected by colorimetry using an ultraviolet spectrophotometer to detect the product concentration.

[0059] Control Example 2 Application of a pyrazine-based three-dimensional covalent organic framework having a double interpenetrating structure in photocatalytic synthesis of urea specifically comprises the following steps:

[0060] The double interpenetrating pyrazine-based three-dimensional covalent organic framework material is used as the catalyst, and water is used as the solvent of the reaction system. Under light, the temperature of the space where the photocatalytic intermittent reactor is located is maintained at 25 degrees Celsius. Before the catalytic reaction begins, NH3 and CO2 are introduced into the reactor to remove other gases. After the reaction, the liquid product produced in the experiment is detected by colorimetry using an ultraviolet spectrophotometer to detect the product concentration.

[0061] Combined with Example 2 and Control Group Example 2, by Figure 7 It can be seen that the maximum rate of photocatalytic NH3 and CO2 production of urea by the doubly interpenetrating tetrazine-based three-dimensional covalent organic framework material is greater than 532 μmol g -1 h -1 The maximum rate of photocatalytic NH3 and CO2 production of urea by the doubly interpenetrating pyrazine-based three-dimensional covalent organic framework material is greater than 196 μmol g -1 h -1 The yield of the doubly interpenetrating pyrazine-based three-dimensional covalent organic framework material is lower than that of the doubly interpenetrating tetrazine-based three-dimensional covalent organic framework material; in addition, in Example 2, after each reaction for 1 hour, the post-reaction solution was replaced with a fresh reaction solvent to evaluate the stability of the doubly interpenetrating tetrazine-based three-dimensional covalent organic framework photocatalyst. The results are as follows Figure 8As shown. The doubly interpenetrating tetrazine-based three-dimensional covalent organic framework photocatalyst can produce urea at least four times continuously without significant performance degradation. The results show that the doubly interpenetrating tetrazine-based three-dimensional covalent organic framework as a catalytic material has the advantages of efficient, green and low-cost photocatalytic production of urea.

[0062] The above only introduces the tetrazine-based three-dimensional covalent organic framework with a double interpenetrating structure prepared by using 5,5'-(1,2,4,5-tetrazine-3,6-diyl)diphenyl-1,3-diamine and 1,3,5-tri(p-formylphenyl)benzene as basic building units and the pyrazine-based three-dimensional covalent organic framework with a double interpenetrating structure prepared by using 5,5'-(pyrazine-3,6-diyl)xylene dicarboxaldehyde and 1,3,5-tri(4-aminophenyl)benzene as basic building units as the control group, as well as the photocatalytic synthesis of urea as examples.

[0063] The long glass tube is a high pressure resistant glass tube.

[0064] Parts not described in detail in the present invention belong to common knowledge of those skilled in the art.

[0065] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein with equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a tetrazine-based three-dimensional covalent organic framework having a double interpenetrating structure, characterized in that: The steps include: Step 1: Add 5,5'-(1,2,4,5-tetrazine-3,6-diyl)biphenyl-1,3-diamine and 1,3,5-tri(p-formylphenyl)benzene in a molar ratio of 3:4 into a high pressure glass container containing a mixed solvent of mesitylene and dioxane, and add acetic acid solution; Step 2: nitrogen is injected into the high pressure glass container to degas it, and then the container is evacuated to a vacuum state and sealed; Step 3: Place the sealed glass container in an oven to heat and keep it warm; Step 4: The reactants are cooled to 25 degrees Celsius, filtered, and the precipitate is washed with tetrahydrofuran and acetone, respectively, and vacuum dried to obtain a doubly interpenetrating tetrazine-based three-dimensional covalent organic framework having an ffc topological structure. The structural formula of the tetrazine-based three-dimensional covalent organic framework is The yield is about 60%.

2. The method for preparing a tetrazine-based three-dimensional covalent organic framework having a double interpenetrating structure according to claim 1, characterized in that: In step 1, the total mass of 5,5'-(1,2,4,5-tetrazine-3,6-diyl)biphenyl-1,3-diamine and 1,3,5-tri(p-formylphenyl)benzene contained in each milliliter of the mixed solvent is 15-35 mg.

3. The method for preparing a tetrazine-based three-dimensional covalent organic framework having a double interpenetrating structure according to claim 1, characterized in that: The degassing treatment in step 2 is performed at least 3 times.

4. The method for preparing a tetrazine-based three-dimensional covalent organic framework having a double interpenetrating structure according to claim 1, characterized in that: In step 3, heat to 120 degrees Celsius and keep warm for 72 hours.

5. The method for preparing a tetrazine-based three-dimensional covalent organic framework having a double interpenetrating structure according to claim 1, characterized in that: In step 4, the drying temperature is 60 degrees Celsius, and the drying is carried out until the detergent is completely evaporated.

6. Application of a tetrazine-based three-dimensional covalent organic framework having a double interpenetrating structure in photocatalytic synthesis of urea, characterized in that: The tetrazine-based three-dimensional covalent organic framework with a double interpenetrating structure is a double interpenetrating tetrazine-based three-dimensional covalent organic framework with a ffc topological structure prepared according to the preparation method of a tetrazine-based three-dimensional covalent organic framework with a double interpenetrating structure according to any one of claims 1 to 5.

7. The use of the tetrazine-based three-dimensional covalent organic framework having a double interpenetrating structure in photocatalytic synthesis of urea according to claim 6, characterized in that: In a photocatalytic intermittent reactor, the tetrazine-based three-dimensional covalent organic framework with a double interpenetrating structure is used as a photocatalyst to obtain urea by photocatalytic coupling reaction of NH3 and CO2.

8. The use of the tetrazine-based three-dimensional covalent organic framework with a double interpenetrating structure in photocatalytic synthesis of urea according to claim 7, characterized in that: The photocatalytic temperature is 25 degrees Celsius; the catalytic reaction is carried out under light.

9. The use of the tetrazine-based three-dimensional covalent organic framework with a double interpenetrating structure in photocatalytic synthesis of urea according to claim 8, characterized in that: Water was used as the solvent in the reaction system.

10. Use of the tetrazine-based three-dimensional covalent organic framework with a double interpenetrating structure in photocatalytic synthesis of urea according to claim 9, characterized in that: Under light, the rate of urea production in an NH3 / CO2 atmosphere was 532 μmol g -1 h -1 .

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