CN111793218A - Preparation method and application of Schiff base dicarboxylic acid ligands Zn, Cu metal-organic framework materials - Google Patents

Abstract

The preparation method and application of Schiff base dicarboxylic acid ligands Zn and Cu metal-organic framework materials, the invention relates to a synthesis method and application of metal-organic framework materials, which aims to solve the reduction efficiency of existing MOFs photocatalytic CO ₂ lower problem. Preparation method: add Schiff base dicarboxylic acid ligand and organic medium into the inner liner of the reaction kettle, dissolve Zn salt or Cu salt in the organic solvent, add _HNO3 solution, mix and react at 90-120 ° C, and pass Washing, soaking and drying to obtain Schiff base dicarboxylic acid ligands Zn and Cu metal organic framework materials. The application is to use Schiff base dicarboxylic acid ligands Zn, Cu metal-organic framework materials as photocatalysts for photocatalytic _CO reduction. The invention prepares a metal-organic framework catalyst with good performance through the design of ligands and central metal, shows good reduction efficiency, and realizes good carbon dioxide photocatalytic reduction performance.

Description

Preparation method and preparation method of Schiff base dicarboxylic acid ligand Zn, Cu metal organic framework material application

technical field

The invention relates to a method for synthesizing Zn and Cu metal-organic framework materials containing Schiff base dicarboxylic acid ligands, and the application of the metal-organic framework materials in photocatalytic CO ₂ reduction.

Background technique

With the rapid development of the national economy, the demand for fossil energy continues to increase, especially the consumption of fossil fuels is increasing. The fossil fuels coal, oil and natural gas currently used are all non-renewable energy sources. As its consumption grows, supply is bound to be tight. In addition, the burning of fossil fuels produces large amounts of carbon dioxide, increasing the amount of carbon dioxide in the atmosphere. Carbon dioxide can lead to the greenhouse effect and has a certain impact on climate change. According to statistics, the concentration of carbon dioxide in the atmosphere is constantly rising, reaching 390 ppm in 2011. Since then, the concentration of carbon dioxide in the atmosphere has continued to increase. Carbon dioxide emissions are expected to increase further in the coming decades. Therefore, from the perspective of saving resources, protecting the environment and sustainable development, the comprehensive utilization of carbon dioxide is of great significance.

Using carbon dioxide as raw material to prepare chemical products is one of the effective ways to balance the carbon cycle and reduce carbon dioxide emissions. In addition, the use of carbon dioxide into fuel is expected to provide a renewable energy source. It has great practical significance for saving energy. Inspired by photosynthesis in nature, researchers have made active efforts in the field of photocatalytic CO2 reduction directly using sunlight, and prepared simple C1/C2 fuels by using suitable photocatalysts to introduce solar energy into the CO2 reduction process ( Such as CO, CH ₄ , CH ₃ OH, C ₂ H ₅ OH, HCHO and HCOO ^- etc.). Solar energy is a kind of renewable energy, and photocatalysis can effectively utilize solar energy, which has the advantages of environmental protection and economy, and has become an effective method for _CO2 treatment in recent years.

The early used photocatalyst is TiO ₂ , which can photocatalyze the reduction of carbon dioxide, and then many inorganic semiconductor photocatalysts have been developed, including WO ₃ , Sr ₂ Nb ₂ O ₆ , Bi ₂ WO ₆ and so on. However, most inorganic semiconductors have large band gap widths and only show photocatalytic activity in the ultraviolet range, in addition, their inherent non-porous structure causes the photocatalytic reaction to proceed only on the outer surface, which affects the catalytic performance.

Metal-organic frameworks (MOFs) are porous crystalline materials with a network structure, which are self-assembled by metal ions or their oxygen clusters and organic ligands through chemical coordination bonds. MOFs have large specific surface area, tunable pore size and shape, and have the advantages of large pores and long channels. Currently, MOFs have been used in _CO capture and conversion, and excellent performance can be obtained by tuning the pore structure and surface charge of MOFs. In photocatalytic _CO2 reduction, MOFs are usually used as photocatalysts, in which organic ligands absorb visible light and metals serve as active sites to utilize solar energy for photocatalytic reduction of _CO2 . Wang et al. (Journal of the American Chemical Society, 2011, 133:13445-13454) used 2,2'-bipyridine-5,5'-dicarboxylic acid ligands to coordinate with rhenium, and then complexed with zirconium ions to synthesize The visible-light-responsive photosensitizer-functionalized MOF photocatalyst can catalyze the reduction of CO ₂ to CO under visible light. Li et al. (Chemical Science, 2014, 5:3808-3813) reported a metal-organic framework synthesized from 2-phenylpyridine, 2,2-bipyridine-4,4-dicarboxylic acid and metal iridium and yttrium. These transition metal-derived metal-organic frameworks exhibit wider absorption bands that can be extended to the visible light region, and thus have better visible-light-driven photocatalytic _CO reduction capabilities. Xu et al. (Journal of the American Chemical Society, 2015, 137:13440-13443) utilized 4,4',4",4"-(porphyrin-5,10,15,20-tetrayl)tetrabenzoate A zirconium porphyrin metal-organic framework material was constructed with zirconium, which can effectively suppress the electron-hole recombination, thereby improving the _CO2 photoreduction efficiency. Chen et al. (Journal of Materials Chemistry A, 2016, 4:2657-2662) used an electron-rich conjugated linker 4,4'-(anthracene-9,10-diylbis(acetylene-2,1- Diyl))) dibenzoic acid reacted with zirconium tetrachloride to synthesize a new type of metal organic framework material, which can catalytically reduce CO ₂ under visible light to generate HCOO ^- .

Researchers have done a lot of research on the catalytic conversion of carbon dioxide. Since _CO2 is thermodynamically very stable, its selective activation and conversion is difficult. Therefore, how to prepare efficient catalysts and improve the conversion efficiency of carbon dioxide has become the main problem faced in this field. From the current research, although MOFs have made some progress in photocatalytic _CO reduction, from the perspective of practical application, it is necessary to develop metal-organic framework materials with better performance to achieve better and efficient photocatalysis _CO2 reduction.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a preparation method and application of Schiff base dicarboxylic acid ligands Zn and Cu metal organic framework materials in order to solve the problem of low reduction efficiency of CO ₂ in photocatalysis of existing MOFs.

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

Add Schiff base dicarboxylic acid ligand and organic medium to the polytetrafluoroethylene liner of the reaction kettle, and then dissolve Zn(NO ₃ ) ₂ ·6H ₂ O or Cu(NO ₃ ) ₂ ·3H ₂ O in the organic In the solvent, the metal salt solution is obtained, the metal salt solution is added to the inner tank of polytetrafluoroethylene, the _HNO3 solution is added, and stirred for 0.5 to 2 hours, and then the inner tank of polytetrafluoroethylene is put into the reaction kettle, and the temperature is 90 to 120. React at ℃ for 18 to 36 hours, terminate the reaction, (slowly) drop to room temperature, filter the reaction solution, wash the collected solid phase with an organic solvent for several times, then soak in the organic solvent, wash and dry to obtain a Schiff base Dicarboxylic acid ligands Zn, Cu metal organic framework materials;

(L₁)或者

(L₂)。Described Schiff base dicarboxylic acid ligand is

(L ₁ ) or

(L ₂ ).

The application of the Schiff base dicarboxylic acid ligand Zn and Cu metal organic framework material of the present invention is to use the Schiff base dicarboxylic acid ligand Zn and Cu metal organic framework material as a photocatalyst for photocatalytic CO ₂ reduction.

The invention utilizes Schiff base dicarboxylic acid ligands to synthesize zinc and copper metal organic framework materials, and the metal organic framework materials can reduce carbon dioxide by photocatalysis. Zinc and copper have the advantages of low cost and good stability of the formed metal organic framework. In addition, zinc and copper as metal cluster centers have better semiconductor properties. The Schiff base dicarboxylic acid ligand of the present invention contains a relatively large conjugated structure, which is conducive to enhancing and expanding spectral absorption, and the -OH group introduced into the organic ligand can enhance the interaction with carbon dioxide molecules, which is conducive to improving Catalytic properties of metal organic frameworks. The invention prepares a metal organic framework catalyst with good performance through the design of the ligand and the central metal, shows good reduction efficiency, realizes good carbon dioxide photocatalytic reduction performance, and the formaldehyde yield can reach 65 μmol g ^{− 1} h ^-1 or more.

Description of drawings

Fig. ₁ is the infrared spectrogram of the metal organic framework C that the embodiment obtains;

Fig. ₂ is the infrared spectrogram of the metal organic framework C that the embodiment obtains;

Fig. 3 is the test chart of the photocatalytic carbon dioxide reduction performance of different solvent sacrificial agents in application examples 6 and 7, wherein 1 represents CH ₃ CN+TEOA, 2 represents DMF+TEOA, 3 represents CH ₃ CN+TEA, and 4 represents DMF +TEA;

Fig. 4 is the variation test chart of formaldehyde generation amount with temperature in application embodiment eight, nine, ten;

Fig. 5 is the test chart of the photocatalytic carbon dioxide reduction performance of the catalyst dosage in Application Example 12.

Detailed ways

Embodiment 1: The preparation method of the Schiff base dicarboxylic acid ligands Zn and Cu metal-organic framework materials of the present embodiment is implemented according to the following steps:

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

Add Schiff base dicarboxylic acid ligand and organic medium to the polytetrafluoroethylene liner of the reaction kettle, and then dissolve Zn(NO ₃ ) ₂ ·6H ₂ O or Cu(NO ₃ ) ₂ ·3H ₂ O in the organic In the solvent, the metal salt solution is obtained, the metal salt solution is added to the inner tank of polytetrafluoroethylene, the _HNO3 solution is added, and stirred for 0.5 to 2 hours, and then the inner tank of polytetrafluoroethylene is put into the reaction kettle, and the temperature is 90 to 120. React at ℃ for 18 to 36 hours, terminate the reaction, (slowly) drop to room temperature, filter the reaction solution, wash the collected solid phase with an organic solvent for several times, then soak in the organic solvent, wash and dry to obtain a Schiff base Dicarboxylic acid ligands Zn, Cu metal organic framework materials;

(L₁)或者

(L₂)。Described Schiff base dicarboxylic acid ligand is

(L ₁ ) or

(L ₂ ).

Embodiment 2: The difference between this embodiment and Embodiment 1 is that the molar ratio of the Schiff base dicarboxylic acid ligand to Zn(NO ₃ ) ₂ ·6H ₂ O or Cu(NO ₃ ) ₂ ·3H ₂ O is 1:1.5～1:3.

Embodiment 3: The difference between this embodiment and Embodiment 1 or 2 is that the organic medium is N,N-dimethylformamide (DMF), N,N-diethylformamide (DEF), One or more mixtures _of methanol (CH3OH).

Embodiment 4: The difference between this embodiment and one of Embodiments 1 to 3 is that the organic solvent is one or more mixed solvents of DMF, DEF, methanol, tetrahydrofuran (THF) and acetone.

Embodiment 5: The difference between this embodiment and one of Embodiments 1 to 4 is that the concentration of the HNO ₃ solution is 1 to 5 mol/L.

The added amount of the HNO ₃ solution in this embodiment is 50-200 μL.

Embodiment 6: The difference between this embodiment and one of Embodiments 1 to 5 is that the soaking treatment time in an organic solvent is 24-48 hours.

Embodiment 7: The application of Schiff base dicarboxylic acid ligands Zn and Cu metal organic framework materials in this embodiment is to use Schiff base dicarboxylic acid ligands Zn and Cu metal organic framework materials as photocatalysts for photocatalysis of CO ₂ reduction.

Embodiment 8: The difference between this embodiment and Embodiment 7 is that the process of using Schiff base dicarboxylic acid ligands Zn and Cu metal organic framework materials as photocatalysts for photocatalytic _CO reduction is as follows:

The Schiff base dicarboxylic acid ligand Zn, Cu metal-organic framework material, sacrificial agent, solvent and deionized water were added to the reaction flask, followed by nitrogen bubbling and carbon dioxide bubbling, and the photocatalytic reaction was carried out with xenon lamp illumination.

The dosage of the Schiff base dicarboxylic acid ligand Zn and Cu metal organic framework material in this embodiment is 10-50 mg, the solvent is 5-50 mL, the sacrificial agent is 1-5 mL, and the deionized water is 1-5 mL.

Embodiment 9: The difference between this embodiment and Embodiment 8 is that the sacrificial agent is triethanolamine, triethylamine or a mixture of the two.

Embodiment 10: The difference between this embodiment and the eighth embodiment is that the photocatalytic reaction time is 3 to 10 hours at 25-50° C. with xenon lamp illumination.

Embodiment 1: The preparation method of the Schiff base dicarboxylic acid ligand Zn metal-organic framework material of the present embodiment is implemented according to the following steps:

The Schiff base dicarboxylic acid ligand L ₁ (0.16 g, 0.40 mmol) and 50 mL of DMF were added to the polytetrafluoroethylene liner of the reaction kettle, and then Zn(NO ₃ ) ₂ .6H ₂ O (0.24 g, 0.8mmol) was dissolved in DMF solution (6mL) to obtain a metal salt solution, the metal salt solution was added to the inner tank of polytetrafluoroethylene, 3mol/L HNO ₃ (100 μL) was added, stirred for 0.5 hours, and then the polytetrafluoroethylene was added. The ethylene liner was put into the reaction kettle, put into a drying oven, reacted at 100 ° C for 36 hours, terminated the reaction, (slowly) lowered to room temperature, filtered the reaction solution, and the collected solid phase was washed 3 times with DMF/CH ₃ OH , and then soaked in acetone for 36 hours, washed with acetone three times, and dried to obtain zinc metal organic framework material C ₁ (brown solid).

Embodiment 2: The preparation method of the Schiff base dicarboxylic acid ligand Zn metal-organic framework material of the present embodiment is implemented according to the following steps:

The Schiff base dicarboxylic acid ligand L ₂ (0.18 g, 0.35 mmol) and 60 mL of DMF were added to the polytetrafluoroethylene liner of the reaction kettle, and then Zn(NO ₃ ) ₂ .6H ₂ O (0.21 g, 0.7mmol) was dissolved in DMF solution (5mL) to obtain a metal salt solution, the metal salt solution was added to the inner tank of polytetrafluoroethylene, 3mol/L of HNO ₃ (150μL) was added, stirred for 1 hour, and then the polytetrafluoroethylene was added. The ethylene liner was put into the reactor, put into a drying oven, reacted at 100 ° C for 24 hours, terminated the reaction, (slowly) lowered to room temperature, filtered the reaction solution, and the collected solid was washed 3 times with DMF/CH ₃ OH , and then soaked in acetone for 24 hours, washed three times with acetone, and dried to obtain zinc metal organic framework material C ₂ (brown solid).

Embodiment 3: The preparation method of the Schiff base dicarboxylic acid ligand Cu metal-organic framework material of the present embodiment is implemented according to the following steps:

The Schiff base dicarboxylic acid ligand L ₁ (0.16 g, 0.40 mmol) and 50 mL of DMF were added to the polytetrafluoroethylene liner of the reaction kettle, and then Cu(NO ₃ ) ₂ .3H ₂ O (0.19 g, 0.8mmol) was dissolved in DMF solution (5mL) to obtain a metal salt solution, the metal salt solution was added to the inner tank of polytetrafluoroethylene, 3mol/L HNO ₃ (200μL) was added, stirred for 0.5 hours, and then the polytetrafluoroethylene was added. The ethylene liner was put into the reactor, put into a drying oven, reacted at 100 ° C for 24 hours, terminated the reaction, (slowly) lowered to room temperature, filtered the reaction solution, and the collected solid was washed 3 times with THF/CH ₃ OH , and then soaked in acetone for 24 hours, washed with acetone three times, and dried to obtain copper metal organic framework material C ₃ (dark green solid).

Embodiment 4: The preparation method of the Schiff base dicarboxylic acid ligand Cu metal-organic framework material of the present embodiment is implemented according to the following steps:

The Schiff base dicarboxylic acid ligand L ₂ (0.18g, 0.35mmol) and 60mL of DMF were added to the polytetrafluoroethylene liner of the reaction kettle, and then Cu(NO ₃ ) ₂ .3H ₂ O (0.17g, 0.7mmol) was dissolved in DMF solution (5mL) to obtain a metal salt solution, the metal salt solution was added to the inner tank of polytetrafluoroethylene, 3mol/L of HNO ₃ (150μL) was added, stirred for 0.5 hours, and then the polytetrafluoroethylene was added. The ethylene liner was put into the reactor, put into a drying oven, reacted at 110 ° C for 24 hours, terminated the reaction, (slowly) lowered to room temperature, filtered the reaction solution, and the collected solid phase was washed 3 times with DMF/CH ₃ OH , and then soaked in acetone for 24 hours, washed with acetone three times, and dried to obtain copper metal organic framework material C ₄ (dark green solid).

Embodiment 5: The preparation method of the Schiff base dicarboxylic acid ligand Cu metal-organic framework material of this embodiment is implemented according to the following steps:

The Schiff base dicarboxylic acid ligand L ₁ (0.16 g, 0.40 mmol) and 50 mL of DMF were added to the polytetrafluoroethylene liner of the reaction kettle, and then Cu(NO ₃ ) ₂ .3H ₂ O (0.19 g, 0.8mmol) was dissolved in MeOH solution (5mL) to obtain a metal salt solution, the metal salt solution was added to the inner tank of polytetrafluoroethylene, 5mol/L HNO ₃ (150μL) was added, stirred for 1 hour, and then the polytetrafluoroethylene was added. The ethylene liner was put into the reactor, put into a drying oven, reacted at 100 ° C for 36 hours, terminated the reaction, (slowly) lowered to room temperature, filtered the reaction solution, and the collected solid was washed 3 times with DMF/THF, and then Soak in acetone for 24 hours, wash with acetone three times, and dry to obtain copper metal organic framework material C ₃ (dark green solid).

Application Example 1: The metal organic framework material C ₁ (0.015g), triethanolamine (5mL), deionized water (5mL) and DMF (25mL) were added to the reaction flask, nitrogen was bubbled for 20 minutes, and carbon dioxide was bubbled for 30 minutes. minutes, the temperature of the thermostatic system was kept at 25°C, and the reaction was irradiated with a 300W Xe lamp for 7 hours to terminate the reaction.

In this example, the product was analyzed by gas chromatography (GC), and the obtained formaldehyde was 6.86 μmol (formaldehyde yield: 65 umol g ⁻¹ h ⁻¹ ).

Application Example 2: The metal organic framework material C ₁ (0.015g), triethylamine (2mL), deionized water (2mL) and DMF (6mL) were added to the reaction flask, nitrogen was bubbled for 20 minutes, and carbon dioxide was bubbled For 30 minutes, the temperature of the constant temperature system was kept at 25°C, and the reaction was irradiated with 300W Xe light for 7 hours to terminate the reaction.

The product was analyzed by gas chromatography (GC) in this example. The resulting formaldehyde was 5.58 μmol.

Application Example 3: The metal organic framework material C ₂ (0.015g), triethylamine (2mL), deionized water (2mL) and acetonitrile (8mL) were added to the reaction flask, nitrogen was bubbled for 20 minutes, and carbon dioxide was bubbled For 30 minutes, the temperature of the constant temperature system was kept at 25°C, and the reaction was irradiated with 300W Xe light for 6 hours to terminate the reaction.

In this example, the product was analyzed by gas chromatography (GC), and the obtained formaldehyde was 5.73 μmol (formaldehyde yield: 63 umol g ⁻¹ h ⁻¹ ).

Application Example 4: The metal organic framework material C ₂ (0.010g), triethanolamine (3mL), deionized water (3mL) and DMF (9mL) were added to the reaction flask, nitrogen was bubbled for 20 minutes, and carbon dioxide was bubbled for 30 minutes. minutes, the constant temperature system was kept at 25°C, and the reaction was irradiated with 300W Xe light for 6 hours to terminate the reaction.

The product was analyzed by gas chromatography (GC) in this example. The resulting formaldehyde was 6.77 μmol.

Application Example 5: The metal organic framework material C ₂ (0.015g), triethylamine (2mL), deionized water (2mL) and DMF (10mL) were added to the reaction flask, nitrogen was bubbled for 20 minutes, and carbon dioxide was bubbled For 30 minutes, the temperature of the constant temperature system was kept at 35°C, and the reaction was irradiated with 300W Xe light for 7 hours to terminate the reaction.

In this example, the product was analyzed by gas chromatography (GC), and the obtained formaldehyde was 9.33 μmol (formaldehyde yield: 88 umol g ⁻¹ h ⁻¹ ).

Application Example 6: Add metal-organic framework material C ₂ (0.010g), triethanolamine (2mL), deionized water (3mL) to two reaction flasks respectively, and then add acetonitrile (6mL) to the two reaction flasks respectively , DMF (6mL), respectively, nitrogen was bubbled for 20 minutes, carbon dioxide was bubbled for 30 minutes, the temperature of the constant temperature system was maintained at 25°C, and the reaction was terminated by illuminating the reaction with 300W Xe light for 7 hours.

In this example, the products in the two reaction flasks were analyzed by gas chromatography (GC), and the obtained formaldehyde was 7.75 μmol and 9.31 μmol (as shown in FIG. 3 ).

Application Example 7: Add metal-organic framework material C ₂ (0.010g), triethylamine (2mL), deionized water (3mL) to the two reaction flasks respectively, and then add acetonitrile (6mL) to the two reaction flasks respectively. ), DMF (6mL), respectively, nitrogen was bubbled for 20 minutes, carbon dioxide was bubbled for 30 minutes, the temperature of the constant temperature system was maintained at 25 ° C, and the reaction was irradiated with a 300W Xe lamp for 7 hours to terminate the reaction.

In this example, the products in the two reaction flasks were analyzed by gas chromatography (GC), and the obtained formaldehyde was 3.83 μmol and 3.92 μmol (as shown in FIG. 3 ).

Application Example 8: The metal organic framework material C ₂ (0.015g), triethanolamine (2mL), deionized water (2mL) and DMF (6mL) were added to the reaction flask, nitrogen was bubbled for 20 minutes, and carbon dioxide was bubbled for 30 minutes. minutes, the constant temperature system was kept at 25°C, and the reaction was irradiated with 300W Xe light for 6 hours to terminate the reaction.

The product was analyzed by gas chromatography (GC) in this example. The resulting formaldehyde was 6.73 μmol (as shown in FIG. 4 ).

Application Example 9: The metal organic framework material C ₂ (0.015g), triethanolamine (2mL), deionized water (2mL) and DMF (6mL) were added to the reaction flask, nitrogen was bubbled for 20 minutes, and carbon dioxide was bubbled for 30 minutes. minutes, the temperature of the thermostatic system was kept at 35°C, and the reaction was irradiated with 300W Xe light for 6 hours to terminate the reaction.

In this example, the product was analyzed by gas chromatography (GC), and the obtained formaldehyde was 7.12 μmol (as shown in FIG. 4 ).

Application Example Ten: The metal organic framework material C ₂ (0.015g), triethanolamine (2mL), deionized water (2mL) and DMF (6mL) were added to the reaction flask, nitrogen was bubbled for 20 minutes, and carbon dioxide was bubbled for 30 minutes. minutes, the temperature of the thermostatic system was kept at 50°C, and the reaction was irradiated with a 300W Xe lamp for 6 hours to terminate the reaction.

In this example, the product was analyzed by gas chromatography (GC), and the obtained formaldehyde was 9.36 μmol (as shown in FIG. 4 ).

Application Example Eleven: The metal organic framework C ₃ (0.015g), triethanolamine (3mL), deionized water (3mL) and DMF (12mL) were added to the reaction flask, nitrogen was bubbled for 20 minutes, and carbon dioxide was bubbled for 30 minutes. minutes, the temperature of the thermostatic system was kept at 25°C, and the reaction was irradiated with a 300W Xe lamp for 7 hours to terminate the reaction.

In this example, the product was analyzed by gas chromatography (GC), and the obtained formaldehyde was 6.06 μmol.

Application Example Twelve: Add 0.010, 0.015, 0.020, 0.025g of metal organic framework material C ₂ to four reaction flasks, and then add triethanolamine (2mL), deionized water (4mL) and DMF (8mL) respectively , bubbling nitrogen for 20 minutes, bubbling carbon dioxide for 30 minutes, maintaining the temperature of the constant temperature system at 25°C, and illuminating the reaction with 300W Xe light for 6 hours to terminate the reaction.

In this example, the products in the four reaction vials were analyzed by gas chromatography (GC). The obtained formaldehyde was 7.83, 9.32, 8.57, 7.86 μmol (as shown in FIG. 5 ).

Application Example Thirteen: The metal organic framework material C ₁ (0.020g), triethylamine (2mL), deionized water (2mL) and acetonitrile (8mL) were added to the reaction flask, nitrogen was bubbled for 20 minutes, carbon dioxide was bubbled After soaking for 30 minutes, the temperature of the constant temperature system was kept at 35°C, and the reaction was irradiated with 300W Xe light for 6 hours to terminate the reaction.

In this example, the product was analyzed by gas chromatography (GC), and the obtained formaldehyde was 6.69 μmol, and the formic acid was 1.36 μmol.

Claims (10)

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

Or

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 ℃.

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