阅读说明：本技术 希夫碱二羧酸配体Zn、Cu金属有机骨架材料的制备方法和应用 (Preparation method and application of Schiff base dicarboxylic acid ligand Zn and Cu metal organic framework material ) 是由 胡明刚 王晓雄 宋新锋 于 2020-08-12 设计创作，主要内容包括：希夫碱二羧酸配体Zn、Cu金属有机骨架材料的制备方法和应用,本发明涉及一种金属有机骨架材料的合成方法及其应用,它为了解决现有MOFs光催化CO<Sub>2</Sub>的还原效率较低的问题。制备方法：向反应釜内胆中加入希夫碱二羧酸配体和有机介质,将Zn盐或者Cu盐溶于有机溶剂中,加入HNO<Sub>3</Sub>溶液,混合后在90～120℃下反应,经过洗涤、浸泡、干燥,得到希夫碱二羧酸配体Zn、Cu金属有机骨架材料。应用是将希夫碱二羧酸配体Zn、Cu金属有机骨架材料作为光催化剂用于光催化CO<Sub>2</Sub>还原。本发明通过对配体和中心金属的设计,制备出性能良好的金属有机骨架催化剂,表现出良好的还原效率,实现了较好的二氧化碳光催化还原性能。(The invention relates to a preparation method and application of a Schiff base dicarboxylic acid ligand Zn and Cu metal organic framework material, and aims to solve the problem of the existing MOFs photocatalysis CO 2 The reduction efficiency of (2) is low. The preparation method comprises the following steps: adding Schiff base dicarboxylic acid ligand and organic medium into the inner container of the reaction kettle, dissolving Zn salt or Cu salt in organic solvent, and adding HNO 3 And (3) mixing the solutions, reacting at 90-120 ℃, washing, soaking and drying to obtain the Schiff base dicarboxylic acid ligand Zn and Cu metal organic framework material. The application is that Schiff base dicarboxylic acid ligand Zn and Cu metal organic framework material is used as photocatalyst for photocatalysisTo convert CO 2 And (4) reducing. The invention prepares the metal organic framework catalyst with good performance by designing the ligand and the central metal, shows good reduction efficiency and realizes better carbon dioxide photocatalytic reduction performance.)

1. The preparation method of the Schiff base dicarboxylic acid ligand Zn and Cu metal organic framework material is characterized by comprising the following steps:

adding Schiff base dicarboxylic acid ligand and organic medium into a polytetrafluoroethylene inner container of a reaction kettle, and then adding Zn (NO)₃)₂·6H₂O or Cu (NO)₃)₂·3H₂Dissolving O in organic solvent to obtain metal salt solution, adding the metal salt solution into the inner container of polytetrafluoroethylene, adding HNO₃Stirring the solution for 0.5-2 hours, then placing a polytetrafluoroethylene inner container into a reaction kettle, reacting for 18-36 hours at 90-120 ℃, stopping the reaction, cooling to room temperature, filtering the reaction solution, washing the collected solid phase substance for multiple times by using an organic solvent, soaking in the organic solvent, washing and drying to obtain Schiff base dicarboxylic acid ligand Zn and Cu metal organic framework materials;

the Schiff base dicarboxylic acid ligand is

2. The process according to claim 1, wherein the Schiff base dicarboxylic acid ligand Zn, Cu metal-organic framework material is formed by reacting Schiff base dicarboxylic acid ligand with Zn (NO)₃)₂·6H₂O or Cu (NO)₃)₂·3H₂The molar ratio of O is 1: 1.5-1: 3.

3. The method for preparing the Schiff base dicarboxylic acid ligand Zn and Cu metal-organic framework material according to claim 1, wherein the organic medium is one or more of N, N-dimethylformamide, N-diethylformamide and methanol.

4. The method for preparing the Schiff base dicarboxylic acid ligand Zn and Cu metal-organic framework material according to claim 1, wherein the organic solvent is one or more of DMF, DEF, methanol, tetrahydrofuran and acetone.

5. The method for preparing Schiff base dicarboxylic acid ligand Zn, Cu metal-organic framework material according to claim 1, wherein the HNO is HNO₃The concentration of the solution is 1-5 mol/L.

6. The method for preparing the Schiff base dicarboxylic acid ligand Zn and Cu metal-organic framework material according to claim 1, wherein the soaking treatment time in the organic solvent is 24-48 hours.

7. Use of the Schiff base dicarboxylic acid ligand Zn, Cu metal organic framework material prepared according to claim 1, characterized in that the Schiff base dicarboxylic acid ligand Zn, Cu metal organic framework material is used as photocatalyst for photocatalysis of CO₂And (4) reducing.

8. The use of the Schiff base dicarboxylic acid ligand Zn, Cu metal organic framework material according to claim 7, wherein the Schiff base dicarboxylic acid ligand Zn, Cu metal organic framework material is used as a photocatalyst for photocatalysis of CO₂The reduction process is as follows:

adding Schiff base dicarboxylic acid ligand Zn, Cu metal organic framework material, sacrificial agent, solvent and deionized water into a reaction bottle, carrying out nitrogen bubbling and carbon dioxide bubbling in sequence, and carrying out photocatalytic reaction under the illumination of a xenon lamp.

9. The use of Schiff base dicarboxylic acid ligand Zn, Cu metal organic framework material according to claim 8, wherein the sacrificial agent is triethanolamine, triethylamine or a mixture of the two.

10. The application of the Schiff base dicarboxylic acid ligand Zn and Cu metal-organic framework material according to claim 8, wherein the application is characterized in that the application is realized by irradiating with a xenon lamp, and the photocatalytic reaction time is 3-10 hours at 25-50 ℃.

Technical Field

The invention relates to a method for synthesizing Zn and Cu metal organic framework materials containing Schiff base dicarboxylic acid ligands, which comprises the following stepsAnd application of the metal organic framework material in photocatalysis of CO₂Application in reduction.

Background

The rapid development of national economy has continued to increase the demand for fossil energy, and in particular, the consumption of fossil fuels has increased. The currently used fossil fuel coal, oil and natural gas are non-renewable energy sources. As its consumption increases, supply is necessarily strained. In addition, fossil fuels produce large amounts of carbon dioxide during combustion, resulting in an increasing carbon dioxide content in the atmosphere. Carbon dioxide can cause greenhouse effect and has certain influence on climate change. It is statistical that the concentration of carbon dioxide in the atmosphere is rising continuously, reaching 390ppm in 2011, and thereafter, the concentration of carbon dioxide in the atmosphere is continuously increasing. The emission of carbon dioxide is expected to increase further in the next decades. Therefore, the comprehensive utilization of carbon dioxide is of great significance from the viewpoints of resource saving, environmental protection and sustainable development.

The preparation of chemical products by taking carbon dioxide as a raw material is one of effective ways for balancing carbon cycle and reducing carbon dioxide emission. In addition, the carbon dioxide is converted into fuel, so that a renewable energy source is hopefully provided. Has great practical significance for saving energy. Inspired by photosynthesis in nature, researchers have made active efforts in the field of photocatalytic carbon dioxide reduction using direct sunlight to produce simple C1/C2 fuels (e.g., CO, CH) by introducing solar energy into the carbon dioxide reduction process using a suitable photocatalyst₄、CH₃OH、C₂H₅OH, HCHO and HCOO^-Etc.). Solar energy is a renewable energy source, the photocatalysis method can effectively utilize the solar energy, has the advantages of environmental protection and economy, and becomes a method for treating CO in recent years₂An effective method of (1).

Early used photocatalyst was TiO₂Photocatalytic reduction of carbon dioxide has been possible, and subsequently a number of inorganic semiconductor photocatalysts have been developed, including WO₃，Sr₂Nb₂O₆、Bi₂WO₆And the like. However, most inorganic semiconductors have a large bandThe width of the gap, which shows photocatalytic activity only in the ultraviolet range, and in addition, its inherent non-porous structure causes photocatalytic reaction only at the outer surface, thereby affecting catalytic performance.

The Metal Organic Frameworks (MOFs) are porous crystalline materials with a network structure, which are formed by self-assembling metal ions or oxygen clusters thereof and organic ligands through chemical coordination bonds. The MOFs has the advantages of large specific surface area, adjustable aperture and shape, large pores, long channels and the like, shows excellent performance in the aspects of gas storage and separation, catalysis, chemical sensing and the like, and is widely concerned. At present, MOFs are in CO₂By adjusting the pore structure and surface charge of the MOFs, excellent performance can be obtained. In the photocatalysis of CO₂In reduction, MOFs are usually used as photocatalysts, wherein organic ligands absorb visible light, metal is used as an active site, and solar photocatalysis is utilized to reduce CO₂. Wang et al (Journal of the American chemical Society,2011,133:13445-13454) synthesized a visible-light-responsive photosensitizer-functionalized MOF photocatalyst by coordinating a 2,2 '-bipyridine-5, 5' -dicarboxylic acid ligand with rhenium, and then complexing with zirconium ions, and catalytically reduced CO under visible light₂CO is generated. Li et al (Chemical Science,2014,5:3808-₂Reducing power. Xu et al (Journal of the American Chemical Society,2015,137:13440-₂Photoreduction efficiency. Chen et al (Journal of Materials Chemistry A,2016,4: 2657-2662)) synthesized a novel metal-organic framework material by reacting an electron-rich conjugated linker 4,4' - (anthracene-9, 10-diylbis (acetylene-2, 1-diyl)) dibenzoic acid with zirconium tetrachloride, which can be visualized under visible lightCatalytic reduction of CO₂Generating HCOO^-。

Researchers have made a great deal of research on the catalytic conversion of carbon dioxide. Due to CO₂Is thermodynamically very stable, and its selective activation and transformation are difficult. Therefore, how to prepare a high-efficiency catalyst and improve the conversion efficiency of carbon dioxide become a main problem in the field. From the current research, although MOFs are in photocatalysis of CO₂Although some progress is made in reduction, from the practical application point of view, the development of a metal organic framework material with more excellent performance is necessary to realize better high-efficiency photocatalysis of CO₂And (4) reducing.

Disclosure of Invention

The invention aims to solve the problem of the existing MOFs photocatalytic CO₂The reduction efficiency is low, and provides a preparation method and application of Schiff base dicarboxylic acid ligand Zn and Cu metal organic framework materials.

The preparation method of the Schiff base dicarboxylic acid ligand Zn and Cu metal organic framework material is realized according to the following steps:

adding Schiff base dicarboxylic acid ligand and organic medium into a polytetrafluoroethylene inner container of a reaction kettle, and then adding Zn (NO)₃)₂·6H₂O or Cu (NO)₃)₂·3H₂Dissolving O in organic solvent to obtain metal salt solution, adding the metal salt solution into the inner container of polytetrafluoroethylene, adding HNO₃Stirring the solution for 0.5-2 hours, then placing a polytetrafluoroethylene inner container into a reaction kettle, reacting for 18-36 hours at 90-120 ℃, terminating the reaction, (slowly) cooling to room temperature, filtering the reaction solution, washing the collected solid phase substance for multiple times by using an organic solvent, soaking in the organic solvent, washing and drying to obtain the Schiff base dicarboxylic acid ligand Zn and Cu metal organic framework material;

the Schiff base dicarboxylic acid ligand is(L₁) Or

(L₂)。

The application of the Schiff base dicarboxylic acid ligand Zn and Cu metal organic framework material is to use the Schiff base dicarboxylic acid ligand Zn and Cu metal organic framework material as a photocatalyst for photocatalysis of CO₂And (4) reducing.

The invention utilizes Schiff base dicarboxylic acid ligand to synthesize zinc and copper metal organic framework materials, and the metal organic framework materials can reduce carbon dioxide by photocatalysis. The zinc and the copper have the advantages of low cost, good stability of the formed metal organic framework and the like. In addition, zinc and copper are used as the centers of the metal clusters, so that the semiconductor has better semiconductor performance. The Schiff base dicarboxylic acid ligand of the invention contains a larger conjugated structure, which is beneficial to enhancing and expanding spectrum absorption, and-OH groups introduced into the organic ligand can enhance the interaction with carbon dioxide molecules and is beneficial to improving the catalytic performance of a metal organic framework. The invention prepares the metal organic framework catalyst with good performance by designing the ligand and the central metal, shows good reduction efficiency, realizes better carbon dioxide photocatalytic reduction performance, and has the formaldehyde yield of 65 mu mol g^-1h^-1The above.

Drawings

FIG. 1 shows the metal-organic framework C obtained in example₃(ii) an infrared spectrum;

FIG. 2 shows the metal-organic framework C obtained in the example₄(ii) an infrared spectrum;

FIG. 3 is a graph showing the performance of photocatalytic carbon dioxide reduction by using different solvent sacrificial agents in six and seven of the application examples, wherein 1 represents CH₃CN + TEOA, 2 for DMF + TEOA, 3 for CH₃CN + TEA, 4 represents DMF + TEA;

FIG. 4 is a graph showing the measurement of the amount of formaldehyde generated in the eighth, ninth and tenth application examples with the change of temperature;

FIG. 5 is a graph showing the reduction performance of photocatalytic carbon dioxide measured by the amount of catalyst used in the twelfth application example.

Detailed Description