Search

CN-116622041-B - Beta-ketoenamine type covalent organic framework material COF-N32 with triazine structure, preparation method thereof and application thereof in hydrogen peroxide photo-synthesis

CN116622041BCN 116622041 BCN116622041 BCN 116622041BCN-116622041-B

Abstract

The invention provides a beta-ketoenamine covalent organic framework material COF-N32 with a triazine structure, a preparation method thereof and application thereof in hydrogen peroxide photo-synthesis. The preparation method comprises the steps of adding 2,4, 6-trihydroxybenzene-1, 3, 5-trioxymethylene and 2,4, 6-tris (4-aminophenyl) -1,3, 5-triazine into a solvent system comprising 1, 4-dioxane, mesitylene and 3mol/L acetic acid solution, carrying out ultrasonic oscillation, heating for reaction, washing and drying to obtain the covalent organic framework material COF-N32. The beta-ketoenamine type covalent organic framework material COF-N32 with the triazine structure can be synthesized only through solvothermal reaction, is used as a photocatalyst for synthesizing hydrogen peroxide, does not need modification in a heterojunction, protonation and other modes, is simple and convenient to operate, is simple and efficient, safe and stable, has no metal ion release risk, and can be effectively regenerated and recycled after being used.

Inventors

  • TONG MEIPING
  • LIU FUYANG

Assignees

  • 北京大学

Dates

Publication Date
20260508
Application Date
20230517

Claims (6)

  1. 1. Use of a β -ketoenamine type covalent organic framework material COF-N32 having a triazine structure in the biosynthesis of hydrogen peroxide, said material comprising periodic structural units as follows: , the periodic structure units are the same periodic structure units which are omitted, and are characterized in that, The preparation method of the beta-ketoenamine type covalent organic framework material COF-N32 with the triazine structure comprises the following steps: Step A1, adding 2,4, 6-trihydroxybenzene-1, 3, 5-trioxymethylene and 2,4, 6-tris (4-aminophenyl) -1,3, 5-triazine into a solvent system consisting of 1, 4-dioxane, mesitylene and 3 mol/L acetic acid solution according to a molar ratio of 1:1 to obtain a mixed solution, introducing nitrogen into the mixed solution and performing ultrasonic vibration for 15-25 minutes to realize full and uniform mixing, wherein the acetic acid solution is 3 mol/L acetic acid solution, and the volume ratio of the 1, 4-dioxane, mesitylene and 3 mol/L acetic acid solution is (2.8-3.2): 2.8-3.2:1; step A2, placing the mixed solution in a closed reaction container, and reacting for 2-4 days at the temperature of 100-120 ℃ to obtain an initial product; Step A3, cooling a closed reaction container to room temperature, filtering the primary product in the reaction container, washing the primary product for 3-5 times by using acetone, and then drying the washed primary product at 60 ℃ for 12 hours to prepare the beta-ketoenamine type covalent organic framework material COF-N32 with the triazine structure; The application comprises the following steps: step B1, dispersing the beta-ketoenamine type covalent organic framework material COF-N32 with a triazine structure in ultrapure water, river water, tap water or seawater to obtain dispersed liquid; Step B2, introducing oxygen into the dispersed liquid under the dark condition, and stirring for 15-30 minutes to ensure that the liquid reaches adsorption and desorption equilibrium; And B3, irradiating the stirred liquid with visible light for at least 12 hours to complete the photocatalytic synthesis of the hydrogen peroxide.
  2. 2. The method according to claim 1, wherein the amount of 2,4, 6-trihydroxybenzene-1, 3, 5-trioxymethylene is 0.3-0.9 mmol and the amount of 2,4, 6-tris (4-aminophenyl) -1,3, 5-triazine is 0.3-0.9 mmol.
  3. 3. The method of claim 1, wherein the total amount of the solvent system in the step A1 is 3.5-10.5 mL.
  4. 4. The use according to claim 1, further comprising: and B4, filtering and separating the beta-ketoenamine type covalent organic framework material COF-N32 with the triazine structure from the liquid after the photocatalytic synthesis in the step B3, and washing and filtering the liquid with deionized water to complete the regeneration of the beta-ketoenamine type covalent organic framework material COF-N32 with the triazine structure.
  5. 5. The use according to claim 1, wherein in step B1, the concentration of the β -ketoenamine type covalent organic framework material COF-N32 having a triazine structure in the dispersed liquid is 100-1500 mg/L.
  6. 6. The method according to claim 1, wherein the step B3 further comprises irradiating the stirred liquid with visible light at 15-35 ℃ for at least 12 hours to effect photocatalytic synthesis of hydrogen peroxide.

Description

Beta-ketoenamine type covalent organic framework material COF-N32 with triazine structure, preparation method thereof and application thereof in hydrogen peroxide photo-synthesis Technical Field The invention relates to a covalent organic framework material and a preparation method and application thereof, in particular to a beta-ketoenamine type covalent organic framework material COF-N32 with a triazine structure, and a preparation method and application thereof in hydrogen peroxide photo-synthesis. Background Hydrogen peroxide (H 2O2) is widely used in the fields of chemical synthesis, energy storage and water treatment. Currently, anthraquinone processes, electrochemical synthesis and noble metal catalysis are common H 2O2 synthesis processes, but require higher energy input and release toxic byproducts resulting in environmental pollution. H 2O2 photo-synthesis, which can utilize naturally occurring water and oxygen as raw materials and sunlight as an energy input, is considered to be a green sustainable synthesis method. However, due to the metastable nature of H 2O2 during synthesis, some side reactions (e.g., decomposition of H 2O2 into oxygen and water) limit the performance of H 2O2 photosynthesization. The covalent organic frameworks (Covalent Organic Frameworks, COFs) material is a novel nonmetallic crystal polymer, can form a proper intermediate to avoid side reactions of H 2O2 synthesis, and has good prospect in the field of H 2O2 photosynthesis. However, in the conventional COFs materials, the generation or separation of excitons (bound state of electron-hole pairs) is insufficient, which reduces the generation of free charges, thereby limiting the efficiency of H 2O2 photo-synthesis. For example, prior art 1 (CN 112538167B) discloses an alkyl chain modified acylhydrazone bond linked covalent organic framework material and its use in photocatalytic hydrogen peroxide production. However, the yield of hydrogen peroxide synthesized by the COFs material through photocatalysis is low and is only 160 mu mol g -1h-1, the COFs material is limited to a laboratory environment, an O 2 atmosphere and deionized water are needed, the water quality condition of an actual water body is very complex, and the application condition of the material in a natural environment can not be deduced according to the yield of the deionized water. In order to promote the photoexcitation and charge separation of COFs, some prior arts adopt interface regulation strategies, such as means of constructing heterojunction, doping single atoms, etc., or promote material reaction by means of electrocatalytic, etc., to promote the charge separation of COFs, but require multi-step, complex and time-consuming synthesis processes. For example, prior art 2 (CN 114164449 a) discloses a method for preparing hydrogen peroxide by catalytic oxygen reduction using a covalent organic framework catalyst. The COFs material is applied to the field of electrocatalysis, and needs to consume electric power and energy, so that the cost is increased. The overpotential is large because COFs are inherently less conductive. Carbon black is additionally added in the electrocatalytic process to improve conductivity, and the operation is complex. It can be seen that the use of COFs materials for H 2O2 efficient photosynthesis under natural conditions also faces significant challenges. Therefore, it is highly desirable to develop a simple and economical charge control strategy for avoiding side reactions and improving the H 2O2 light synthesis efficiency. Disclosure of Invention In order to solve the defects in the prior art, the invention aims to provide a beta-ketoenamine type covalent organic framework material COF-N32 with a triazine structure, which can efficiently synthesize H 2O2, a preparation method thereof and application thereof in hydrogen peroxide photo-synthesis. The invention adopts the following technical scheme: according to a first aspect of the present invention there is provided a β -ketoenamine type covalent organic framework material COF-N32 having a triazine structure. The material COF-N32 includes a periodic structural unit as shown below: the benzene rings in the periodic structural units are connected with one another to form omitted repeated structural units. According to a second aspect of the present invention, there is provided a method for preparing a β -ketoenamine type covalent organic framework material COF-N32 having a triazine structure according to the first aspect of the present invention. The preparation method comprises the following steps: Step A1, adding 2,4, 6-trihydroxybenzene-1, 3, 5-trioxymethylene and 2,4, 6-tris (4-aminophenyl) -1,3, 5-triazine into a solvent system comprising 1, 4-dioxane, mesitylene and acetic acid solution to obtain a mixed solution and fully and uniformly mixing; Step A2, heating the mixed solution to react to obtain an initial product; and step A3, washing and drying the initial product t