Cd-MOF material and preparation method and application thereof

Abstract

The invention relates to the technical field of photocatalysis, in particular to a Cd-MOF material and a preparation method and application thereof. The preparation method comprises the following steps: dissolving 2, 6-naphthalene dicarboxylic acid, an organic ligand 2, 5-bis (pyridine-4-yl) thiazolo [5, 4-d] thiazole and cadmium nitrate tetrahydrate in N, N-dimethylformamide, uniformly stirring, sealing in a glass bottle, and carrying out solvothermal reaction to obtain a Cd-MOF material; the Cd-MOF material can efficiently photocatalytically degrade dye in water, and Cd-MOF is used as a catalyst, so that the Cd-MOF material has relatively high catalytic activity. The prepared Cd-MOF is used as a catalyst to perform photocatalytic amine oxidative coupling to prepare imine, air is used as an oxygen source, the light utilization rate is high, the reaction condition is mild, and a product with relatively high yield is obtained. The Cd-MOF photocatalyst is short in reaction time, high in catalytic activity, good in stability and capable of being recycled.

Description

Technical Field

[0001] The present invention relates to the field of photocatalysis technology, and in particular to a Cd-MOF material and a preparation method and application thereof. Background Art

[0002] In recent years, with the rapid development of science and technology and society, fossil energy has been developed and utilized in large quantities, resulting in energy shortages and environmental pollution. The development of alternative clean energy is urgent. Compared with traditional thermal catalytic organic synthesis reactions, photocatalytic reactions are widely used in environmental remediation, energy conversion and organic synthesis because of their simple process and environmental friendliness and pollution-free. As an important intermediate, imines have received extensive attention in the fields of medicine and biology. Traditional imine synthesis usually requires unstable aldehydes as raw materials, Lewis acid catalysts and dehydrating agents, so people are committed to developing green, efficient and economical imine synthesis methods. The direct conversion of photocatalytic benzylamine to the corresponding imine provides a positive alternative for the synthesis of imines. Many heterogeneous catalysts have been developed for photocatalytic imine synthesis under mild conditions, but these photocatalysts still have many disadvantages, such as the need to introduce oxygen and high temperature in the reaction, which greatly hinders their practical application. Therefore, it is still challenging to develop an efficient photocatalyst in a reaction system with air as an oxidant at room temperature. Among them, metal organic frameworks (MOFs), as organic-classical inorganic hybrid porous crystalline materials, have a large surface area and easy functionalization structure, and are excellent platforms for constructing photocatalysts. Therefore, the development of MOFs materials with mild conditions and improved light utilization efficiency has important practical significance and application prospects for the photocatalytic preparation of imines.

[0003] Globally, many industries such as textiles, papermaking, food, and pharmaceuticals discharge various toxic and harmful colored dyes into the environment during the production process. These dyes have caused serious damage to aquatic organisms due to their low biodegradability, complex colors, high COD and BOD, etc. Photocatalytic degradation technology has become a research hotspot in the field of environmental governance due to its advantages of environmental protection and efficient degradation. Among them, metal-organic frameworks (MOFs) are organic-inorganic hybrid materials constructed by metal ions and organic ligands. They are widely used in photocatalytic degradation of organic dyes due to their high specific surface area, ideal topological structure, rich surface active sites, and flexible modification. Summary of the invention

[0004] The present invention overcomes the deficiencies of the prior art and provides a Cd-MOF material and a preparation method and application thereof. The present invention adopts a solvothermal method to prepare a Cd-MOF material, which is simple to operate. The Cd-MOF material can efficiently photocatalytically degrade dyes in water, and Cd-MOF is used as a catalyst with high catalytic activity. The prepared Cd-MOF is used as a catalyst to carry out photocatalytic amine oxidative coupling to prepare imines, with air as an oxygen source, high light utilization rate, mild reaction conditions, and a product with a high yield. The Cd-MOF photocatalyst has a short reaction time, high catalytic activity, good stability, and can be recycled.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: a Cd-MOF material, whose molecular formula is C 102 H 98 Cd3N 20 O 12 S6, its crystal system belongs to the Monoclinic system, and the unit cell parameters are: a=45.899(6) Å, b=17.4621(17) Å, c=33.535(4) Å, α=90°, β=132.477(5)°, γ=90°.

[0006] The invention provides a method for preparing a Cd-MOF material. The method comprises the following steps: dissolving 2,6-naphthalene dicarboxylic acid, an organic ligand 2,5-di(pyridin-4-yl)thiazo[5,4-d]thiazole and cadmium nitrate tetrahydrate in N,N-dimethylformamide, stirring the mixture evenly, sealing the mixture in a glass bottle, and performing a solvothermal reaction to obtain the Cd-MOF material.

[0007] As a further limitation of the technical solution of the present invention, the molar ratio of 2,6-naphthalene dicarboxylic acid, 2,5-di(pyridin-4-yl)thiazolo[5,4-d]thiazole and cadmium nitrate tetrahydrate is 1:1:2; the volume ratio of the molar amount of the 2,6-naphthalene dicarboxylic acid to N,N-dimethylformamide is: 3mmol:400mL.

[0008] As a further limitation of the technical solution of the present invention, the temperature of the solvent thermal reaction is 120° C. and the time is 7 days.

[0009] In addition, the present invention also provides the use of the above-mentioned Cd-MOF material in the preparation of imines by photocatalytic amine oxidative coupling.

[0010] As a further limitation of the above technical solution, at room temperature, Cd-MOF material is used as a photocatalyst, benzylamine and its derivatives are used as raw materials, an organic solvent is added, and a catalytic reaction is carried out under the irradiation of simulated visible light and an air atmosphere to obtain imine.

[0011] As a further limitation of the above technical solution, the raw material is benzylamine, 3-methylbenzylamine, 4-bromobenzylamine or 4-chlorobenzylamine; and the organic solvent is anhydrous acetonitrile.

[0012] In addition, the invention also provides the use of the above-mentioned Cd-MOF material in the photocatalytic degradation of dyes in wastewater.

[0013] As a further limitation of the above technical solution, Cd-MOF is added as a catalyst into the wastewater containing the dye, and after the dark reaction adsorption equilibrium is reached, photocatalytic degradation is carried out under the irradiation of visible light.

[0014] Compared with the prior art, the present invention has the following beneficial effects: The invention synthesizes Cd-MOF materials and provides a method for preparing imines by photocatalytic amine oxidative coupling using Cd-MOF materials. By screening the concentration of substrates, reaction atmosphere, catalyst dosage, and solvent types, a series of imines with high yields are obtained under optimized conditions, with a yield of 90%-99%. The catalyst dosage used is small, the catalytic activity is high, the reaction conditions are mild, and the catalyst can be recycled for multiple times. Air is used as an oxygen source, which is low-cost, low-pollution, and environmentally friendly.

[0015] In addition, the present invention also provides a method for photocatalytically degrading dyes in wastewater using the Cd-MOF material synthesized by the present invention. By screening the type of dye, catalyst capacity, concentration of reactants, and pH of the aqueous solution, under optimized conditions, the degradation rate of rhodamine B in water is 99% after 30 minutes, and the catalyst used has good stability and can be recycled for multiple times. This method provides a new idea for constructing Cd-MOF catalysts to achieve photocatalytic degradation of dyes. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Schematic diagram of the crystal structure of Cd-MOF of the present invention.

[0017] Figure 2 This is a crystal molecular model diagram of Cd-MOF of the present invention.

[0018] Figure 3 Characterization pictures of Cd-MOF, where a is the SEM picture, b is the XRD picture, c is the BET picture and D is the TGA picture.

[0019] Figure 4 This is the H NMR spectrum of the corresponding imine in the photocatalytic oxidative coupling of benzylamine.

[0020] Figure 5 This is the H NMR spectrum of the photocatalytic oxidative coupling of 3-methylbenzylamine to the corresponding imine.

[0021] Figure 6This is the H NMR spectrum of the photocatalytic oxidative coupling of 4-bromobenzylamine to the corresponding imine.

[0022] Figure 7 This is the H NMR spectrum of the photocatalytic oxidative coupling of 4-chlorobenzylamine to the corresponding imine.

[0023] Figure 8 This is a graph showing the change of the UV-visible absorption spectrum of Rhodamine B during photocatalytic degradation over time.

[0024] Fig. 9 This is a graph showing the degradation rate of Rhodamine B changing with time under photocatalytic degradation.

[0025] Fig.10 This is the cycling performance diagram of Cd-MOF material photocatalyst. DETAILED DESCRIPTION

[0026] The present invention is further described below in conjunction with specific embodiments. Example

[0027] A method for synthesizing a Cd-MOF material is to dissolve 2,6-naphthalene dicarboxylic acid (0.015 mmol, 3.2 mg), an organic ligand (0.015 mmol, 4.5 g) and cadmium nitrate tetrahydrate (0.03 mmol, 9.24 mg) in 2 mL of N,N-dimethylformamide, stir evenly, seal in a 10 mL glass bottle, and perform a solvothermal reaction (120° C. for 7 days) to obtain Cd-MOF.

[0028] Figure 1 Schematic diagram of the crystal structure of the above-mentioned Cd-MOF material. Figure 2 This is a crystal molecular model diagram of the above-mentioned Cd-MOF material.

[0029] Figure 3 These are the SEM, XRD, BET and TGA characterization pictures of the above Cd-MOF materials.

[0030] The synthesized Cd-MOF material was used for the photocatalytic amine oxidative coupling to prepare imines as described in Examples 2-5, and for the photocatalytic degradation of dyes in wastewater as described in Example 6. Example

[0031] A method for preparing imine by photocatalytic amine oxidative coupling of Cd-MOF, the specific operation steps are as follows: (1) Add 10 mg of Cd-MOF catalyst into a quartz tube, take 0.1 mmol of benzylamine as raw material, add 1 mL of anhydrous acetonitrile as solvent, and mix the system evenly by ultrasonication for 10 min under dark conditions.

[0032] (2) At room temperature and in air atmosphere, a 300W xenon lamp was introduced as the light source to irradiate the quartz tube and the reaction was continued for 6.5 hours.

[0033] (3) After the reaction, the solid catalyst was separated using a 0.45 μm filter membrane, the liquid product was dried, and the yield of the product was evaluated by nuclear magnetic resonance hydrogen spectrum. After detection and analysis, the corresponding imine yield was 99%.

[0034] Figure 4 This is the H NMR spectrum of the corresponding imine in the photocatalytic oxidative coupling of benzylamine. Example

[0035] (1) Add 10 mg of Cd-MOF catalyst into a quartz tube, take 0.1 mmol of 3-methylbenzylamine as raw material, add 1 mL of anhydrous acetonitrile as solvent, and mix the system evenly by ultrasonication for 10 min under dark conditions.

[0036] (2) At room temperature and in air atmosphere, a 300W xenon lamp was introduced as the light source to irradiate the quartz tube and the reaction was continued for 6.5 hours.

[0037] (3) After the reaction, the solid catalyst was separated using a 0.45 μm filter membrane, the liquid product was dried, and the yield of the product was evaluated by nuclear magnetic resonance hydrogen spectrum. After detection and analysis, the corresponding imine yield was 93%.

[0038] Figure 5 This is the H NMR spectrum of the photocatalytic oxidative coupling of 3-methylbenzylamine to the corresponding imine. Example

[0039] (1) Add 10 mg of Cd-MOF catalyst into a quartz tube, take 0.1 mmol of 4-bromobenzylamine as raw material, add 1 mL of anhydrous acetonitrile as solvent, and mix the system evenly by ultrasonication for 10 min under dark conditions.

[0040] (2) At room temperature and in air atmosphere, a 300W xenon lamp was introduced as the light source to irradiate the quartz tube and the reaction was continued for 6.5 hours.

[0041] (3) After the reaction, the solid catalyst was separated using a 0.45 μm filter membrane, the liquid product was dried, and the yield of the product was evaluated by nuclear magnetic resonance hydrogen spectrum. After detection and analysis, the corresponding imine yield was 96%.

[0042] Figure 6 This is the H NMR spectrum of the photocatalytic oxidative coupling of 4-bromobenzylamine to the corresponding imine. Example

[0043] (1) Add 10 mg of Cd-MOF catalyst into a quartz tube, take 0.1 mmol of 4-chlorobenzylamine as raw material, add 1 mL of anhydrous acetonitrile as solvent, and mix the system evenly by ultrasonication for 10 min under dark conditions.

[0044] (2) At room temperature and in air atmosphere, a 300W xenon lamp was introduced as the light source to irradiate the quartz tube and the reaction was continued for 6.5 hours.

[0045] (3) After the reaction, the solid catalyst was separated using a 0.45 μm filter membrane, the liquid product was dried, and the yield of the product was evaluated by nuclear magnetic resonance hydrogen spectrum. After detection and analysis, the corresponding imine yield was 99%.

[0046] Figure 7 This is the H NMR spectrum of the photocatalytic oxidative coupling of 4-chlorobenzylamine to the corresponding imine. Example

[0047] A method for photocatalytic degradation of dyes in wastewater by Cd-MOF, using the Cd-MOF prepared in Example 1, specifically comprises the following steps: (1) 5 mg of Cd-MOF catalyst was dispersed in 15 mL of 100 mg / mL Rhodamine B aqueous solution and then stirred in the dark for 30 min to reach adsorption equilibrium.

[0048] (2) A 300 W xenon lamp was introduced as the light source to photocatalytically degrade the Rhodamine B aqueous solution. A certain amount of the solution was taken every 5 minutes, centrifuged, and the supernatant was analyzed using a UV-visible spectrophotometer.

[0049] Figure 8 The figure shows the change of the UV-visible absorption spectrum of the photocatalytic degradation of Rhodamine B over time. As can be seen from the figure, the Cd-MOF catalyst prepared by the present invention has a photocatalytic effect and can effectively photocatalytically degrade Rhodamine B.

[0050] Fig. 9 This is a graph showing the degradation rate of Rhodamine B over time. The horizontal axis is time and the vertical axis is C t / C0, where C0 is the initial concentration of rhodamine B; C t The concentration of rhodamine B was measured by sampling every 5 minutes; Fig. 9 It can be seen that under simulated visible light irradiation, the degradation rate of Rhodamine B of the Cd-MOF photocatalyst prepared in Example 1 was 99% at 30 min, and the performance was excellent.

[0051] , filter the mixture after the degradation treatment for 30 minutes in step (2) to screen out the Cd-MOF photocatalyst, wash it with water and anhydrous ethanol, and after drying, it can be recycled. The degradation rate of Rhodamine B in the aqueous solution is still up to 90%.

[0052] Fig.10 The cycle performance diagram of the Cd-MOF photocatalyst prepared in Example 1 of the present invention is shown in FIG. Fig.10 It can be seen that the Cd-MOF photocatalyst prepared in Example 1 has good stability and recyclability.

Claims

1. A Cd-MOF material, characterized in that: Its molecular formula is C 102 H 98 Cd3N 20 O 12 S6, its crystal system belongs to the Monoclinic system, and the unit cell parameters are: a=45.899(6) Å, b=17.4621(17) Å, c=33.535(4) Å, α=90°, β=132.477(5)°, γ=90°.

2. The method for preparing a Cd-MOF material according to claim 1, characterized in that: 2,6-naphthalene dicarboxylic acid, organic ligand 2,5-di(pyridin-4-yl)thiazolyl[5,4-d]thiazole and cadmium nitrate tetrahydrate were dissolved in N,N-dimethylformamide, stirred evenly, sealed in a glass bottle, and subjected to solvothermal reaction to obtain Cd-MOF material.

3. The method for preparing a Cd-MOF material according to claim 2, characterized in that: The molar ratio of 2,6-naphthalenedicarboxylic acid, 2,5-di(pyridin-4-yl)thiazolo[5,4-d]thiazole and cadmium nitrate tetrahydrate is 1:1:2; the volume ratio of the molar amount of 2,6-naphthalenedicarboxylic acid to N,N-dimethylformamide is: 3mmol:400mL.

4. The method for preparing a Cd-MOF material according to claim 2, characterized in that: The temperature of the solvent thermal reaction is 120° C. and the time is 7 days.

5. Use of a Cd-MOF material according to claim 1 in preparing imines by photocatalytic amine oxidative coupling.

6. The use according to claim 5, characterized in that: At room temperature, Cd-MOF material is used as a photocatalyst, benzylamine and its derivatives are used as raw materials, an organic solvent is added, and a catalytic reaction is carried out under the irradiation of simulated visible light and an air atmosphere to obtain imine.

7. The use according to claim 6, characterized in that: The raw material is benzylamine, 3-methylbenzylamine, 4-bromobenzylamine or 4-chlorobenzylamine; and the organic solvent is anhydrous acetonitrile.

8. Use of a Cd-MOF material according to claim 1 in photocatalytic degradation of dyes in wastewater.

9. The use according to claim 8, characterized in that: Cd-MOF is added as a catalyst into wastewater containing dyes. After dark reaction adsorption equilibrium is reached, photocatalytic degradation is carried out under the irradiation of visible light.

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