Preparation method of a tetrazine-based three-dimensional covalent organic framework with a dual interpenetrating structure and application thereof in photocatalytic synthesis of urea

Abstract

The application discloses a preparation method of a four-dimension covalent organic framework with a double interpenetrating structure, and comprises the following steps: 1, 5, 5'-(1, 2, 4, 5-tetrazine-3, 6-diyl) bisphenyl-1, 3-diamine and 1, 3, 5-tri-(p-formylphenyl) benzene are added into a high-pressure-resistant glass container containing a mixed solvent of mesitylene and dioxane, and an acetic acid solution is added; 2, nitrogen is injected into the container, and the container is sealed after degassing; 3, the sealed container is placed in an oven, and heating and heat preservation are carried out; 4, the reactants are cooled, filtered, washed, and vacuum dried, so that a double-interpenetrating four-dimension covalent organic framework with an ffc topological structure is obtained, and the structural formula of the four-dimension covalent organic framework is The yield is about 60%; the four-dimension covalent organic framework material with the double interpenetrating structure is obtained through an aldehyde-amine condensation condensation reaction; the preparation method is simple in operation, excellent in photocatalytic performance, and conducive to the recycling of the catalyst; and is suitable for urea production.

Description

TECHNICAL FIELD

[0001] The application 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 interpenetration structure and application thereof in photocatalytic synthesis of urea. BACKGROUND

[0002] Urea, as an important nitrogen fertilizer, is an indispensable raw material in agricultural production. In addition, urea also 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 large amount of energy and emits a large amount of greenhouse gas CO2. Therefore, it is particularly important to synthesize urea by using an energy-saving and environmentally friendly route.

[0003] Covalent organic framework material is a crystalline porous material with precise topological structure and clear pore size distribution linked by covalent bonds. COFs material is composed of some light chemical elements (C, N, B, O, Si) and has excellent pore properties, large specific surface area, good stability and easy functionalization, and is widely used in gas storage and separation, photoelectric materials, catalysis, drug release and energy fields and shows excellent application prospect, thereby attracting wide attention and research of material scientists and chemists and becoming a new type of functional material after metal-organic framework (MOFs). Compared with traditional inorganic porous materials linked by non-covalent bonds, COFs are linked by covalent bonds, so that the pore properties of the material are maintained, and the molecular grid structure is more stable. Due to the diversity of molecular structural units and synthesis methods of COFs, the final COFs material has rich structural composition and controllable pore properties, and more importantly, the final material has corresponding functional properties by purposefully introducing functional building blocks.

[0004] According to the characteristics of covalent organic framework material, the application develops a tetrazine-based three-dimensional covalent organic framework with a double interpenetration structure and imine bond linkage which can catalyze NH3 and CO2 to generate urea at normal temperature and pressure. SUMMARY

[0005] The application provides a preparation method of a tetrazine-based three-dimensional covalent organic framework with a double interpenetration structure and application thereof in photocatalytic synthesis of urea, and aims to solve the existing energy crisis and or global warming environmental problems.

[0006] To achieve the above-mentioned purpose, the technical scheme adopted by the application is as follows:

[0007] A preparation method of a tetrazine-based three-dimensional covalent organic framework with a double interpenetration structure comprises the following steps:

[0008] Step one, 5,5'-(1,2,4,5-tetrazine-3,6-diyl)bisbenzene-1,3-diamine and 1,3,5-tri(p-formylphenyl)benzene are added to a high-pressure resistant glass container containing a mixed solvent of mesitylene and dioxane in a molar ratio of 3:4, and an acetic acid solution is added;

[0009] Step two, the high-pressure resistant glass container is flushed with nitrogen and degassed, and then sealed in a vacuum state;

[0010] Step three, the sealed glass container is placed in an oven for heating and incubation;

[0011] Step four, 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 double-interpenetrated tetrazine-based three-dimensional covalent organic framework with ffc topology, and the structural formula of the tetrazine-based three-dimensional covalent organic framework is The yield is about 60%.

[0012] Further, in step one, the total mass of 5,5'-(1,2,4,5-tetrazine-3,6-diyl)bisbenzene-1,3-diamine and 1,3,5-tri(p-formylphenyl)benzene in the mixed solvent per milliliter is 15-35 milligrams.

[0013] Further, in step two, the degassing treatment is at least 3 times.

[0014] Further, in step three, the heating is to 120 degrees Celsius, and the incubation is for 72 hours.

[0015] Further, in step four, the drying temperature is 60 degrees Celsius, and the drying is until the washing agent is completely evaporated.

[0016] The application of a tetrazine-based three-dimensional covalent organic framework with a double-interpenetrated structure in the photocatalytic synthesis of urea, wherein the tetrazine-based three-dimensional covalent organic framework with a double-interpenetrated structure is a double-interpenetrated tetrazine-based three-dimensional covalent organic framework with ffc topology prepared by the method for preparing a tetrazine-based three-dimensional covalent organic framework with a double-interpenetrated structure according to any one of claims 1-5.

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

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

[0019] Further, water is used as the solvent of the reaction system.

[0020] Further, under irradiation, in NH3 / CO2 atmosphere, the rate of urea production is 532 μmol g -1 h -1 .

[0021] The present application has at least one of the following technical progresses compared with the prior art due to the adoption of the above structure:

[0022] 1. The four-dimensional covalent organic framework material with a dual interpenetrating structure is obtained by aldehyde amine condensation reaction of 5,5'-(1,2,4,5-tetrazine-3,6-diyl) bisphenyl-1,3-diamine and 1,3,5-tri-p-(formylphenyl) benzene. Under light driving, it has very excellent performance of photocatalytic coupling of NH3 and CO2 to generate urea.

[0023] 2. The preparation method of the four-dimensional covalent organic framework with a dual interpenetrating structure is simple in operation, has excellent photocatalytic performance, is conducive to recycling of the catalyst, and has excellent potential for practical commercial application.

[0024] 3. The catalytic reaction system of the four-dimensional covalent organic framework material with a dual interpenetrating structure is pure water, and has the characteristics of green reaction system, no pollution, and low cost. BRIEF DESCRIPTION OF DRAWINGS

[0025] The accompanying drawings are included to provide a further understanding of the present application, and constitute a part of the specification, illustrate the present application together with the embodiments thereof, and explain the principles of the present application, and do not constitute a limitation of the present application.

[0026] In the drawings:

[0027] Figure 1 is a schematic diagram of the molecular structure of the four-dimensional covalent organic framework of the present application;

[0028] Figure 2 is a schematic diagram of the dual interpenetrating structure of the four-dimensional covalent organic framework of the present application;

[0029] Figure 3 is a powder X-ray diffraction spectrum of the four-dimensional covalent organic framework with a dual interpenetrating structure of the present application;

[0030] Figure 4 is a high-resolution transmission electron microscope characterization diagram of the four-dimensional covalent organic framework with a dual interpenetrating structure of the present application;

[0031] Figure 5 is a schematic diagram of the molecular structure of the four-dimensional covalent organic framework of the present application;

[0032] Figure 6X-ray powder diffraction pattern of the pyrazine-based three-dimensional covalent organic framework of the present application with dual interpenetrating structure;

[0033] Figure 7 Schematic diagram of the yield of urea catalyzed by the tetrazine-based three-dimensional covalent organic framework and the pyrazine-based three-dimensional covalent organic framework of the present application for the production of urea;

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

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

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

[0037] This embodiment 1 discloses a preparation method of a tetrazine-based three-dimensional covalent organic framework with dual interpenetrating structure, as shown in the following formula: Figure 1 The tetrazine-based three-dimensional covalent organic framework (3D-TBBD-COF) with dual interpenetrating structure is mainly synthesized by Schiff base reaction of aldehyde amine condensation of 5,5'-(1,2,4,5-tetrazine-3,6-diyl) biphenyl-1,3-diamine and 1,3,5-tris(p-formylphenyl) benzene, and is linked by covalent bond between the two, and 5,5'-(1,2,4,5-tetrazine-3,6-diyl) biphenyl-1,3-diamine is synthesized as a new connecting unit: Step one: dissolve 3,5-diaminobenzonitrile, hydrazine hydrate and sulfur powder in ethanol; Step two: heat and stir the obtained solution at 90 degrees Celsius for 10 hours, and after the reaction is completed, wash with ethanol and acetone; Step three: dry in a vacuum oven at 60 degrees Celsius to obtain a bright yellow powder; Step four: disperse the bright yellow powder in dry dimethyl sulfoxide and pass in oxygen; Step five: add 150 milliliters of distilled water to the oxidized compound, and the fresh red product is dispersed in the H2O2 solution, and the red product 5,5'-(1,2,4,5-tetrazine-3,6-diyl) biphenyl-1,3-diamine is separated by centrifugation; 1,3,5-tris(p-formylphenyl) benzene is an existing product and can be purchased in the market.

[0038] A preparation method of a tetrazine-based three-dimensional covalent organic framework with dual interpenetrating structure, which is specifically prepared by the following method:

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

[0040] Step two, flush nitrogen into the long glass tube, perform three cycles of freeze-pumping-thawing to degas, and seal it with a flame after being pumped into a vacuum state;

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

[0042] Step four, cool the reactants to 25 degrees Celsius, collect the precipitated solids by filtration, and wash them with tetrahydrofuran (2x20ml) and acetone (3x20ml), then dry the obtained solids at 60 degrees Celsius under vacuum until the washing agents are completely evaporated, to obtain a double-interpenetrated tetrazine-based three-dimensional covalent organic framework material with ffc topology, with a yield of about 60%, and the structural formula of the tetrazine-based three-dimensional covalent organic framework is

[0043] Perform structural analysis on the double-interpenetrated tetrazine-based three-dimensional covalent organic framework prepared above, and obtain the results as shown in Figures 1-4

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

[0045] As can be seen from Figure 2 , the tetrazine-based three-dimensional covalent organic framework has a clear double-interpenetrated structure.

[0046] As can be seen from Figure 3 , the tetrazine-based three-dimensional covalent organic framework with a double-interpenetrated structure has sharp diffraction peaks.

[0047] As can be seen from Figure 4 , the double-interpenetrated tetrazine-based three-dimensional covalent organic framework has clear lattice fringes, indicating that it is a highly crystalline framework material.

[0048] ​Example 1, a control group, discloses a method for preparing a pyrazine-based three-dimensional covalent organic framework with a dual interpenetrating structure. This method is used to compare and study the advantages of a tetrazine-based three-dimensional covalent organic framework with a dual interpenetrating structure in the photocatalytic synthesis of urea. Figure 5 As shown, the pyrazine-based three-dimensional covalent organic framework (3D-PDDP-COF) with a double interpenetrating structure is synthesized mainly by using 5,5'-(pyrazine-3,6-diyl)di-m-phenylcarboxaldehyde and 1,3,5-tris(4-aminophenyl)xylbenzene as novel linking units: Step 1: 3,5-dicarboxyphenylboronic acid, potassium carbonate, and tetra-triphenylphosphine palladium were dissolved in a mixed solution of dioxane and water under argon atmosphere; Step 2: The resulting solution was heated and stirred at 110°C for 24 hours. After the reaction was completed, the solvent was evaporated under reduced pressure; Step 3: The product was extracted with ethyl acetate and water, and then evaporated to dryness; Step 4: The crude product was purified by silica gel flash column chromatography to obtain pure 5,5'-(pyrazine-3,6-diyl)di-m-phenylcarboxaldehyde; 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 dual interpenetrating structure, specifically through the following method:

[0050] Step 1: Add 5,5'-(pyrazine-3,6-diyl)di-m-phenylenedialdehyde and 1,3,5-tris(4-aminophenyl)benzene to a long glass tube in a molar ratio of 3:4 into a mixed solvent of mesitylene and dioxane. Each milliliter of the mixed solvent contains 15-35 mg of the total mass of 5,5'-(pyrazine-3,6-diyl)m-m-phenylenedialdehyde and 1,3,5-tris(4-aminophenyl)benzene. Acetic acid solution is added to catalyze the reaction.

[0051] Step 2: Pour nitrogen into the long glass tube and perform three cycles of freezing-evacuation-thawing to degas the tube, then evacuate it to a vacuum state and seal it with a flame.

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

[0053] Step 4: Cool the reactants to 25°C, filter to collect the precipitate, and wash with tetrahydrofuran (2×20 ml) and acetone (3×20 ml). Dry the resulting solid under vacuum at 60°C until the washings are completely evaporated to obtain a pyrazine-based three-dimensional covalent organic framework material with the same structure as the tetraazine-based three-dimensional covalent organic framework, with a yield of approximately 70%. The structural formula of the pyrazine-based three-dimensional covalent organic framework is as follows:

[0054] Structural analysis was performed on the pyrazine-based three-dimensional covalent organic framework with the double interpenetrating structure prepared above, and the results were as follows:Figures 5-6 The results shown are as follows:

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

[0056] like Figure 6 As shown, pyrazine-based three-dimensional covalent organic frameworks with double interpenetrating structures also exhibit sharp diffraction peaks.

[0057] Example 2: Application of a tetraazine-based three-dimensional covalent organic framework with a dual interpenetrating structure in the photocatalytic synthesis of urea, specifically including the following steps:

[0058] A tetrazine-based three-dimensional covalent organic framework with a double interpenetrating structure was used as the catalyst, and water was used as the solvent in the reaction system. Under light irradiation, the temperature of the space in the photocatalytic batch reactor was maintained at 25 degrees Celsius. Before the catalytic reaction started, NH3 and CO2 were introduced into the reactor to remove other gases. After the reaction was completed, the concentration of the liquid product produced in the experiment was detected by colorimetric method using a UV spectrophotometer.

[0059] Example 2, a control group, describes the application of a pyrazine-based three-dimensional covalent organic framework with a dual interpenetrating structure in the photocatalytic synthesis of urea. The specific steps include:

[0060] A pyrazine-based three-dimensional covalent organic framework with a double interpenetrating structure was used as the catalyst, and water was used as the solvent in the reaction system. Under light irradiation, the temperature of the space in the photocatalytic batch reactor was maintained at 25 degrees Celsius. Before the catalytic reaction started, NH3 and CO2 were introduced into the reactor to remove other gases. After the reaction was completed, the concentration of the liquid product produced in the experiment was detected by colorimetric method using a UV spectrophotometer.

[0061] Combining Example 2 and Control Group Example 2, by Figure 7 It is known that the highest photocatalytic rate of urea production from NH3 and CO2 by the tetrazine-based three-dimensional covalent organic framework material with a double interpenetrating structure is greater than 532 μmol g. -1 h -1 The highest photocatalytic rate of urea production from NH3 and CO2 by pyrazine-based three-dimensional covalent organic framework materials with a double interpenetrating structure is greater than 196 μmol g. -1 h -1 The yield of the pyrazine-based three-dimensional covalent organic framework material with a double interpenetrating structure was lower than that of the tetrazine-based three-dimensional covalent organic framework material with a double interpenetrating structure. Furthermore, in Example 2, the reaction solution was replaced with fresh reaction solvent every 1 hour to evaluate the stability of the tetrazine-based three-dimensional covalent organic framework photocatalyst with a double interpenetrating structure. The results are as follows: Figure 8As shown, the tetrazine-based three-dimensional covalent organic framework photocatalyst with a double interpenetrating structure can continuously produce urea at least four times without significant performance degradation. The results indicate that the tetrazine-based three-dimensional covalent organic framework with a double interpenetrating structure has the advantages of efficient, green, and low-cost photocatalytic urea production.

[0062] The above descriptions only cover the tetrazine-based three-dimensional covalent organic framework with a double interpenetrating structure prepared using 5,5'-(1,2,4,5-tetraazine-3,6-diyl)bisphenyl-1,3-diamine and 1,3,5-tris(p-formylphenyl)benzene as basic building blocks, the pyrazine-based three-dimensional covalent organic framework with a double interpenetrating structure prepared using 5,5'-(pyrazine-3,6-diyl)xylbenzene-xylenediformaldehyde and 1,3,5-tris(4-aminophenyl)benzene as basic building blocks, and the photocatalytic synthesis of urea.

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

[0064] The parts of this invention not described in detail are common knowledge to those skilled in the art.

[0065] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within 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 with a dual interpenetrating structure, characterized in that: Includes the following steps: Step 1: Add 5,5'-(1,2,4,5-tetraazine-3,6-diyl)bisphenyl-1,3-diamine and 1,3,5-tris(p-formylphenyl)benzene in a molar ratio of 3:4 to a high-pressure resistant glass container containing a mixture of trimethylolpropene and dioxane, and add acetic acid solution. Step 2: Pour nitrogen into the high-pressure resistant glass container to degas it, then evacuate it to a vacuum state and seal it. Step 3: Place the sealed glass container in an oven, heat it, and keep it warm. Step 4: Cool the reactants to 25°C, filter, wash the precipitate with tetrahydrofuran and acetone respectively, and dry under vacuum to obtain a tetraazine-based three-dimensional covalent organic framework with an FFC topology. The structural formula of the tetraazine-based three-dimensional covalent organic framework is as follows: .

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

3. The method for preparing a tetrazine-based three-dimensional covalent organic framework with a dual interpenetrating structure according to claim 1, characterized in that: The degassing process in step two shall be performed at least three times.

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

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

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

7. The application of the tetraazine-based three-dimensional covalent organic framework with a double interpenetrating structure according to claim 6 in the photocatalytic synthesis of urea, characterized in that: In a photocatalytic batch reactor, the tetrazine-based three-dimensional covalent organic framework with a double interpenetrating structure serves as a photocatalyst to convert NH3 and CO2 into urea via a photocatalytic coupling reaction.

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

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

10. The application of the tetraazine-based three-dimensional covalent organic framework with a dual interpenetrating structure according to claim 9 in the photocatalytic synthesis of urea, characterized in that: Under light irradiation and in an NH3 / CO2 atmosphere, the rate of urea production is 532 µmol g. -1 h -1 .

Images