An NH2-MIL-53 / UiO-66-NH2 catalyst for photocatalytic reduction of CO2, its preparation method and its uses

Abstract

The application discloses an NH2-MIL-53 / UiO-66-NH2 catalyst for photocatalytic reduction of CO2, a preparation method and application thereof. By means of a surfactant-assisted growth method, a zirconium-based metal organic framework UiO-66-NH2 with an octahedron and NH2-MIL-53 are combined, a composite material of hierarchical core-shell NH2-MIL-53 / UiO-66-NH2 is successfully prepared, and is used for photocatalytic reduction of CO2 under visible light. By adjusting the band gap of the metal organic framework material, the application improves the separation and transfer efficiency of photo-generated carriers, has excellent photocatalytic reduction performance of CO2, and has a simple preparation method and certain application prospect.

Description

Technical Field

[0001] This invention belongs to the technical field of MOF-on-MOF nanocomposite material preparation and its photocatalytic reduction of CO2, and relates to an NH2-MIL-53 / UiO-66-NH2 composite material with photocatalytic CO2 reduction performance and its preparation method. Background Technology

[0002] The rapid development of modern technology has led to excessive carbon dioxide emissions and global warming. Significant efforts have been made to address this challenge. Currently, carbon capture and storage (CFS) technology is a recognized working method. Captured carbon dioxide is injected into underground geological structures for permanent storage. However, catalytically converting captured carbon dioxide into high-value chemicals and / or fuels is more feasible than simply storing it as waste. Therefore, utilizing solar energy to reduce carbon dioxide is one of the most promising solutions. In the past few decades, semiconductors, zeolites, and metal complexes have been widely used for CO2 photoreduction, but these molecular systems are mostly limited to expensive noble metal catalysts. Therefore, developing photocatalysts with broad visible light responsiveness is quite necessary.

[0003] Metal-organic frameworks (MOFs) are a new class of crystalline porous materials that have recently attracted considerable attention. Due to the high porosity and tunability of MOFs, they can interact with carbon dioxide molecules. The metal clusters in MOFs can behave as inorganic semiconductor quantum entities, and organic connectors can act as antennas to activate these metal clusters under photoexcitation, thus making "MOF-based photocatalysis" possible.

[0004] Among them, the binary MOF photocatalyst not only maintains the high porosity, crystallinity and properties of the single parent MOF, but the obtained binary MOF hierarchical structure also has an extended light response, an optimized band gap, and a greatly enhanced effective separation of photogenerated charges. Summary of the Invention:

[0005] The purpose of this invention is to provide an NH2-MIL-53 / UiO-66-NH2 composite material, its preparation, and its application. A hierarchical core-shell structured MOF-on-MOF photocatalyst composite material of NH2-MIL-53 / UiO-66-NH2 was prepared using a surfactant-assisted growth method. The combination of NH2-MIL-53 and UiO-66-NH2 enhances the photocatalytic reduction of CO2. The prepared photocatalyst facilitates photogenerated charge separation and transfer, and also exhibits an extended light response, optimized band gap, and good visible light photocatalytic activity.

[0006] To achieve the objectives of this invention, the following technical solution was adopted:

[0007] The preparation method of NH2-MIL-53 / UiO-66-NH2 composite material includes the following steps:

[0008] (1) Preparation of NH2-MIL-53: Metal salt and organic ligand were added to N,N-dimethylformamide, a regulator was added, the mixture was stirred, heated, and centrifuged to obtain sample NH2-MIL-53;

[0009] (2) Preparation of NH2-MIL-53 / UiO-66-NH2: The sample NH2-MIL-53 synthesized in step (1) was added to the mother liquor of UiO-66-NH2, and a surfactant was added; after complete dissolution, the mixture was stirred, heated, and centrifuged to obtain the sample NH2-MIL-53 / UiO-66-NH2 composite material.

[0010] Preferably, the metal salt in step (1) is FeCl3·6H2O or FeCl x Or Fe(NO3) x Or Fe(NO3) x ·9H2O, X=2,3; any one of them;

[0011] Preferably, the organic ligand in step (1) is aminoterephthalic acid;

[0012] Preferably, the molar ratio of the metal salt to the organic ligand in step (1) is 6:5 to 9:5, for example, 6:5, 7:5, 8:5, or 9:5; the concentration of the dissolved organic ligand is 0.1852 to 0.202 mol·L⁻¹. -1 Preferably, the medium regulator in step (1) is any one of formic acid, acetic acid, propionic acid, and hydrochloric acid; the volume is 5 to 10 mL, for example 5 mL, 6 mL, 7 mL, 8 mL, 9 mL, or 10 mL.

[0013] Preferably, in step (1), the volume ratio of the regulator to N,N-dimethylformamide is 1:5 to 1:10;

[0014] Preferably, the reaction temperature in step (1) is 120–150°C; for example, 120°C, 130°C, 140°C, 150°C.

[0015] Preferably, the reaction time in step (1) is 20 to 24 hours, for example, 20 hours, 21 hours, 22 hours, 23 hours, or 24 hours.

[0016] Preferred method for preparing UiO-66-NH2 mother liquor in step (2): dissolve zirconium salt and aminoterephthalic acid in solvent, stir to dissolve, and obtain mixed solution;

[0017] Preferably, in the preparation method of UiO-66-NH2 mother liquor in step (2), the zirconium salt is selected from any one of zirconium chloride, zirconium nitrate, and zirconium chloride octahydrate;

[0018] Preferably, in the preparation method of UiO-66-NH2 mother liquor in step (2), the molar ratio of metal salt to organic ligand amino terephthalic acid is 3:1 to 1:3;

[0019] Preferably, in the preparation method of UiO-66-NH2 mother liquor in step (2), the solvent is selected from a mixed solution of acetic acid and water, which is green and environmentally friendly, and the volume ratio is acetic acid:water = 1:4 to 3:2; for example, 1:4, 1:3, 1:2, 1:1, 2:1, 3:1, 3:2.

[0020] Preferably, in step (2), the concentration of the UiO-66-NH2 mother liquor after dissolution of aminoterephthalic acid is 0.0254–0.0308 mol·L⁻¹. -1 Preferably, in step (2), the molar ratio of NH2-MIL-53 to UiO-66-NH2 is 5:1 to 1:1; for example, 5:1, 4:1, 3:1, 2:1, 1:1; the concentration of the dispersed NH2-MIL-53 is 0.0236 to 0.05917 mol·L. -1 ;

[0021] Preferably, the surfactant in step (2) is selected from polyvinylpyrrolidone (PVP) with a molecular weight of 30,000; the mass ratio of the surfactant to NH2-MIL-53 is 1:1.

[0022] Preferably, the reaction temperature in step (2) is 100–120°C; the reaction time is 12–20 h. A second objective of this invention is to provide a composite catalyst NH2-MIL-53 / UiO-66-NH2, which is prepared as described above. A third objective of this invention is to provide an application of the NH2-MIL-53 / UiO-66-NH2 catalyst described above, for photocatalytic CO2 reduction. Weigh 1–5 mg of catalyst, 0.1 mL of water, 0.1 mL of triethylamine, and 0.4 mL of acetonitrile. Then, using visible light or a xenon lamp as the photocatalytic light source and carbon dioxide as the reaction atmosphere, first equilibrate under dark conditions for one hour at a reaction pressure of 0.05–1 MPa, and then proceed with the photocatalytic reaction.

[0023] The beneficial technical effects of the present invention are as follows:

[0024] A hierarchical core-shell NH2-MIL-53 / UiO-66-NH2 composite material was successfully prepared by combining octahedral zirconium-based metal-organic frameworks UiO-66-NH2 and NH2-MIL-53 using a surfactant-assisted growth method. This composite material is used for photocatalytic reduction of CO2 under visible light. This invention improves the separation and transfer efficiency of photogenerated carriers by adjusting the band gap of the metal-organic framework material, exhibiting excellent photocatalytic CO2 reduction performance. Furthermore, the preparation method is simple and shows promising application prospects.

[0025] The preparation method provided by this invention is simple, uses water as a solvent, is green and environmentally friendly, easy to implement, has a high yield, and is easy to mass-produce. Attached image description:

[0026] Figure 1 The image shows the XRD pattern of the NH2-MIL-53 / UiO-66-NH2 composite material in the embodiments of the present invention.

[0027] Figure 2 This is a SEM image of the NH2-MIL-53 / UiO-66-NH2 composite material in an embodiment of the present invention.

[0028] Figure 3 The image shows the photocatalytic performance of the NH2-MIL-53 / UiO-66-NH2 composite material in the embodiments of the present invention. Detailed implementation method:

[0029] This invention is not limited to the specific embodiments listed below. Those skilled in the art can implement this invention using various other specific embodiments based on the content disclosed herein. Any modifications or alterations made to the design structure and concept of this invention fall within the protection scope of this invention. It should be noted that, unless otherwise specified, the embodiments and features described in this invention can be combined with each other.

[0030] Implementation Case 1

[0031] Preparation of NH2-MIL-53 / UiO-66-NH2 composite material:

[0032] (1) Ferric chloride (0.86 g) and aminoterephthalic acid (0.102 g) were dissolved in 50 mL of N,N-dimethylformamide and 5 mL of acetic acid, and reacted at 100 °C for 24 h. After centrifugation and drying, NH2-MIL-53 was obtained, yielding iron-based rod-shaped MOF nanorods.

[0033] (2) Aminoterephthalic acid (0.046 g) and zirconium chloride octahydrate (0.104 g) were dissolved in a mixture of 5 mL water and 5 mL acetic acid. 0.1 g NH2-MIL-53 and 0.1 g polyvinylpyrrolidone were added, and the mixture was reacted at 100 °C for 20 h. After centrifugation and drying, a hierarchical core-shell MOF-on-MOF structure was obtained by the NH2-MIL-53 / UiO-66-NH2 composite material.

[0034] (3) Weigh 5 mg of catalyst, 0.1 mL of water, 0.1 mL of triethylamine, and 0.4 mL of acetonitrile. Use a 300 W xenon lamp as the light source for the photocatalytic experiment and carbon dioxide as the reaction atmosphere. First, equilibrate in the dark for one hour at a reaction pressure of 0.1 MPa, and then irradiate with light. Take samples every hour and analyze the results using gas chromatography.

[0035] Implementation Case 2

[0036] (1) Ferric chloride (0.56 g) and aminoterephthalic acid (0.224 g) were dissolved in 60 mL of N,N-dimethylformamide and 10 mL of acetic acid, and reacted at 100 °C for 24 h. After centrifugation and drying, NH2-MIL-53 was obtained, yielding iron-based rod-shaped MOF nanorods.

[0037] (2) Aminoterephthalic acid (0.056 g) and zirconium chloride octahydrate (0.228 g) were dissolved in a mixture of 6 mL water and 4 mL acetic acid. 0.1 g NH₂-MIL-53 and 0.1 g polyvinylpyrrolidone were added, and the mixture was reacted at 100 °C for 24 h. The solution was then centrifuged and dried to obtain…

[0038] The composite material of NH2-MIL-53 / UiO-66-NH2 was used to obtain a hierarchical core-shell MOF-on-MOF structure. (3) Weigh 3 mg of catalyst, 0.1 mL of water, 0.1 mL of triethylamine and 0.4 mL of acetonitrile. Use a 300W xenon lamp as the light source for the photocatalytic experiment and carbon dioxide as the reaction atmosphere. First, equilibrate in the dark for one hour at a reaction pressure of 0.1 MPa, and then irradiate. Take samples every hour and analyze the results by gas chromatography.

[0039] Implementation Case 3

[0040] (1) Ferric chloride (0.12 g) and aminoterephthalic acid (0.105 g) were dissolved in 70 mL of N,N-dimethylformamide and 7 mL of acetic acid, and reacted at 100 °C for 24 h. After centrifugation and drying, NH2-MIL-53 was obtained, yielding iron-based rod-shaped MOF nanorods. (2) Aminoterephthalic acid (0.043 g) and zirconium chloride octahydrate (0.058 g) were dissolved in a mixed solution of 15 mL of water and 10 mL of acetic acid. 0.1 g of NH2-MIL-53 and 0.1 g of polyvinylpyrrolidone were added, and the mixture was reacted at 120 °C for 12 h. After centrifugation and drying, a composite material of NH2-MIL-53 / UiO-66-NH2 was obtained, yielding a hierarchical core-shell MOF-on-MOF structure. (3) Weigh 5 mg of catalyst, 0.1 mL of water, 0.1 mL of triethylamine, and 0.4 mL of acetonitrile. Use a 300W xenon lamp as the light source for the photocatalytic experiment and carbon dioxide as the reaction atmosphere. First, equilibrate in the dark for one hour at a reaction pressure of 0.1 MPa, then irradiate with light. Take samples every hour and analyze the results using gas chromatography. The above content is only a preferred embodiment of the present invention, but the present invention should not be limited to the content disclosed in this embodiment. Therefore, any equivalent or modified versions made without departing from the spirit of the present invention fall within the scope of protection of the present invention.

Claims

1. An NH2-MIL-53 / UiO-66-NH2 catalyst for photocatalytic reduction of CO2, characterized in that, The catalyst has a hierarchical core-shell structure with NH2-MIL-53 as the core and UiO-66-NH2 as the outer shell.

2. The method for preparing the NH2-MIL-53 / UiO-66-NH2 catalyst for photocatalytic reduction of CO2 as described in claim 1, characterized in that, Includes the following steps: (1) Preparation of NH2-MIL-53: Metal salt and organic ligand were added to N,N-dimethylformamide, a regulator was added, the mixture was stirred, heated, and centrifuged to obtain sample NH2-MIL-53; (2) Preparation of NH2-MIL-53 / UiO-66-NH2: The sample NH2-MIL-53 synthesized in step (1) was added to the mother liquor of UiO-66-NH2, and a surfactant was added; the mixture was stirred, heated, and centrifuged to obtain the sample NH2-MIL-53 / UiO-66-NH2 composite material; The preparation method of UiO-66-NH2 mother liquor involves dissolving zirconium salt and aminoterephthalic acid in a solvent, stirring until dissolved, to obtain a mixed solution. The zirconium salt is selected from any one of zirconium chloride, zirconium nitrate, and zirconium chloride octahydrate. The molar ratio of zirconium salt to the organic ligand aminoterephthalic acid is 3:1 to 1:

3. The solvent is selected from a mixed solution of acetic acid and water, with a volume ratio of acetic acid:water = 1:4 to 3:

2. The concentration of the dissolved aminoterephthalic acid is 0.0254 to 0.0308 mol·L⁻¹. -1 ; In step (2), the molar ratio of NH2-MIL-53 to UiO-66-NH2 is 5:1 to 1:1; the concentration of the dispersed NH2-MIL-53 is 0.0236 to 0.05917 mol·L⁻¹. -1 The surfactant is selected from polyvinylpyrrolidone (PVP) with a molecular weight of 30,000; the mass ratio of the surfactant to NH2-MIL-53 is 1:1; the reaction temperature is 100~120 ℃; and the reaction time is 12~20 h.

3. The method for preparing the NH2-MIL-53 / UiO-66-NH2 composite material according to claim 1, characterized in that, The metal salt in step (1) is FeCl3·6H2O or FeCl x Or Fe(NO3) x Or Fe(NO3) x ·9H2O, X=2, 3 (any one); the organic ligand in step (1) is aminoterephthalic acid; the molar ratio of metal salt to organic ligand is 6:5~9:5; the concentration of the dissolved organic ligand is 0.1852~0.202 mol·L -1 The regulator in step (1) is any one of formic acid, acetic acid, propionic acid, or hydrochloric acid; the volume ratio of the regulator to N,N-dimethylformamide is 1:5 to 1:10; the reaction temperature in step (1) is 120 to 150 °C; and the reaction time is 20 to 24 h.

4. The method for preparing the NH2-MIL-53 / UiO-66-NH2 composite material according to claim 1, characterized in that: The particle size of UiO-66-NH2 in the composite material is 50-150 nm, and the particle size of NH2-MIL-53 is 1-2 μm.

5. The application of the NH2-MIL-53 / UiO-66-NH2 composite material as described in claim 1, characterized in that: Used for photocatalytic CO2 reduction under visible light conditions.

6. According to the application described in claim 5, weigh 1-5 mg of catalyst, 0.1 mL of water, 0.1 mL of triethylamine, and 0.4 mL of acetonitrile. Then, use visible light or a xenon lamp as the light source for photocatalysis, and carbon dioxide as the reaction atmosphere. First, equilibrate in the dark for one hour at a reaction pressure of 0.05-1 MPa, and then carry out the photocatalytic reaction.

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