Novel metal organic framework supported catalyst, preparation method and application of novel metal organic framework supported catalyst in photocatalytic CO2 reduction

Abstract

The invention belongs to the field of material synthesis catalysis, and discloses a novel metal organic framework supported catalyst, a preparation method and application thereof in photocatalytic CO2 reduction. A Zn-MOF carrier is synthesized through terephthalic acid, zinc nitrate hexahydrate and 3, 5-diamino-1, 2, 4-triazole, an amide type N, N bidentate coordination site is constructed through covalent modification of picolinic acid ligands, then a metal precursor is loaded, a novel metal organic framework supported catalyst is synthesized, and the novel metal organic framework supported catalyst is applied to photocatalytic CO2 reduction. The Zn-MOF carrier and the catalyst both have the advantage of being simple and convenient to prepare, the catalyst is novel in structure and excellent in catalytic performance, compounding of photo-induced electrons and holes is effectively inhibited through precise loading of Ir metal, directional movement of electrons in a frame is promoted, efficient reaction is achieved with Ir as a CO2 reduction catalytic center, and the catalyst is suitable for large-scale industrial production. The utilization rate of visible light and the efficiency of preparing formic acid by reducing CO2 through photocatalysis are improved.

Description

Technical Field

[0001] This invention belongs to the field of materials synthesis catalysis, and relates to a novel metal-organic framework supported catalyst, its preparation method, and its photocatalytic CO2 reduction application. Background Technology

[0002] With the acceleration of global industrialization and the massive consumption of fossil fuels, energy crises and environmental problems are becoming increasingly prominent. More than 80% of global energy consumption comes from fossil fuels, leading to a sharp rise in atmospheric CO2 levels. Excessive CO2 emissions have triggered a series of environmental problems, including global warming, glacial melting, and biodiversity loss, which have become urgent global challenges. At the same time, CO2, as the most active carbon cycle carrier in the Earth's carbon pool, is also a usable carbon source with enormous potential for conversion into renewable energy and high-value-added chemical products. Realizing the resource-based conversion of CO2 is of significant strategic importance and practical value for alleviating the energy crisis and promoting the achievement of "dual carbon" goals.

[0003] Among numerous CO2 conversion technologies, photocatalytic CO2 reduction technology, by simulating natural photosynthesis, utilizes solar energy to drive the conversion of CO2 and H2O into high-value chemicals such as methanol, ethanol, CO, and CH4. It possesses the dual significance of "carbon reduction" and "energy storage," and boasts unique advantages such as abundant energy, readily available raw materials, mild reaction conditions (room temperature and pressure), and no secondary pollution. It is considered one of the most promising solutions to global energy and environmental problems. The photocatalytic CO2 reduction reaction is a complex multi-step process, mainly including three key steps: first, the semiconductor photocatalyst is excited by light with energy greater than its bandgap, generating photogenerated electrons and holes; second, the effective separation of photogenerated electrons and holes; and third, the migration of photogenerated electrons to the catalyst surface to react with CO2 and H2O. + The reduction reaction generates the target product, while photogenerated holes react with H2O to produce O2. The entire process can be carried out in a pure gas phase or solution system. Metal-organic frameworks (MOFs) are a class of crystalline porous materials formed by the self-assembly of metal ions / clusters and organic ligands through coordination bonds. They possess unique advantages such as high specific surface area, regular and tunable pore structure, abundant active sites, tunable electronic structure, and excellent CO2 adsorption capacity, providing an ideal support platform for constructing highly efficient photocatalytic CO2 reduction catalysts. In recent years, they have received extensive exploration and attention in the field of photocatalytic CO2 conversion.

[0004] Studies have shown that by orderly integrating heterogeneous components such as single-atom catalysts, metal nanoclusters, and quantum dots into the MOF framework, the transport path of photogenerated carriers can be effectively controlled, promoting interfacial charge separation efficiency and thus significantly improving the quantum yield and product selectivity of CO2 photoreduction systems. Among them, zinc-based metal-organic frameworks (Zn-MOFs) have shown good application potential in the field of photocatalytic CO2 reduction due to their good stability, ease of functionalization modification, moderate specific surface area, and excellent CO2 capture ability. However, existing Zn-MOF-based catalysts often suffer from problems such as uneven dispersion of active sites, high photogenerated electron-hole recombination rate, and limited catalytic activity. Furthermore, the complex ligand modification methods during their synthesis make it difficult to achieve precise loading and control of catalytic active centers, thus limiting their industrial application. In 2014, Li's research group prepared three amino-functionalized MOFs using a simple ligand exchange method. These were applied to the photocatalytic reduction of CO2 to formate, demonstrating that the amino-functionalized MOFs exhibited stronger photocatalytic activity than the unfunctionalized MOFs (Acs Catalysis, 2014, 8, 4254-4260). This is mainly due to the introduction of NH2, which not only provides more adsorption sites for CO2 but also increases the absorption capacity of visible light. In addition to directly exciting Fe-O clusters, it also excites NH2 functional clusters, leading to electron transfer to the Fe center and forming a unique dual-excitation pathway. Based on this, the present invention designs a novel amide-type ligand-modified Zn-based MOF support by using polynitrogen heterocyclic compounds containing multiple amino groups, introduces N,N bidentate coordination sites through covalent functionalization modification, and further loads an iridium metal precursor as a catalytic active center. This provides a novel, simple, and easy-to-operate method for preparing an amide-type iridium-based Zn-MOF supported catalyst, and provides its application as a catalyst for the photocatalytic reduction of carbon dioxide to formic acid, thereby overcoming the shortcomings of the prior art. Summary of the Invention

[0005] The purpose of this invention is to achieve functional modification of Zn-MOF materials at the molecular level by designing novel amide-type ligands, synthesizing Zn-MOF supports, and further performing iridium metal functionalization modification. This provides a novel, simple, and high-performance method for preparing amide-type iridium-based metal-organic framework supported catalysts, and offers its application as a photocatalyst for CO2 reduction.

[0006] The technical solution of this invention: A novel metal-organic framework supported catalyst has the following structural formula: , or ; The structural formula of the metal-organic framework carrier is as follows: .

[0007] A method for preparing a novel metal-organic framework supported catalyst includes the following steps: (1) Synthesis of Zn-MOF support: Terephthalic acid, zinc nitrate hexahydrate and 3,5-diamino-1,2,4-triazole were dissolved in a mixed solvent of N,N-dimethylformamide and water, and then reacted under an inert atmosphere and at a certain temperature. After the reaction was completed, the mixture was centrifuged, washed with anhydrous methanol, and finally dried under reduced pressure to obtain Zn-MOF support. The molar ratio of terephthalic acid, zinc nitrate hexahydrate, and 3,5-diamino-1,2,4-triazole is 1:1:1 to 1:2:2, and the concentrations of all three in the reaction system are 0.01-0.022 mol / L. The volume ratio of N,N-dimethylformamide to water in the mixed solvent is 1:1 to 4:3; The inert gas is nitrogen or argon; The specified temperature condition is 85℃; the reaction time is 24-48 hours. The vacuum drying temperature is 80℃; the vacuum drying time is 24-48 hours.

[0008] (2) Synthesis of amide-type Zn-MOF support: Zn-MOF support, pyridine carboxylic acid compound, 1-hydroxybenzotriazole (HOBt) and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDCI) were dissolved in dichloromethane and coupled at room temperature. After the reaction was completed, the mixture was centrifuged, washed with dichloromethane and methanol in sequence, ultrasonically dispersed, filtered, and dried at constant temperature to obtain amide-type Zn-MOF support. The molar ratio of Zn-MOF support, pyridine carboxylic acid compound, 1-hydroxybenzotriazole, and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride is 1:2.2:2.2:2.2-1:4:4:4; The concentration of pyridine carboxylic acid compounds in the reaction system was 0.012-0.018 mol / L; The pyridine carboxylic acid compounds are 2-pyridine carboxylic acid, 6-methoxypyridine-2-carboxylic acid, and 6-hydroxypyridine-2-carboxylic acid; The coupling reaction takes 24-48 hours; The constant temperature drying temperature is 80℃, and the time is 24-48 hours.

[0009] (3) Synthesis of amide-type iridium-based Zn-MOF catalyst: The amide-type Zn-MOF support and dichloro(pentamethylcyclopentadiene)iridium(III) dimer were dissolved in anhydrous methanol and reacted for 24 hours under an inert atmosphere and at 65°C. After cooling to room temperature, the solid particles were collected by centrifugation and then repeatedly washed with anhydrous methanol. After vacuum filtration, the catalyst was dried under vacuum to obtain a novel metal-organic framework supported catalyst.

[0010] The concentration of the dichloro(pentamethylcyclopentadiene)iridium(III) dimer in the reaction system is 0.005-0.01 mol / L; The molar ratio of amide-type Zn-MOF support to dichloro(pentamethylcyclopentadiene)iridium(III) dimer is 4:1-2:1; The inert atmosphere is nitrogen or argon; The drying temperature is 80℃, and the drying time is 24-48 hours.

[0011] A method for photocatalytic CO2 reduction using a novel metal-organic framework supported catalyst includes the following steps: (1) Photocatalytic CO2 reduction to formic acid: Under an inert atmosphere, a novel metal-organic framework supported catalyst and sacrificial agent are dispersed in a solvent, then replaced with carbon dioxide multiple times, and finally placed in a photochemical reactor and stirred for 2-10 hours. The sacrificial agent is one of 1,3-dimethyl-2-phenyl-2,3-dihydro-1H-benzo[d]imidazole (BIH), 1-benzyl-1,4-dihydronicotinamide (BNAH), triethanolamine (TEOA), and triethylamine (TEA); The concentration of the sacrificial agent in the reaction system was 0.004-0.016 mol / L; The molar ratio of novel metal-organic framework supported catalysts to sacrificial agents is 1:2 to 1:30; The solvent is one of the following: anhydrous acetonitrile, a mixed solution of acetonitrile and water in a volume ratio of 1:1 to 29:1, anhydrous N,N-dimethylformamide (DMF), a mixed solution of N,N-dimethylformamide and water in a volume ratio of 1:1 to 29:1, anhydrous N,N-dimethylacetamide (DMA), a mixed solution of N,N-dimethylacetamide and water in a volume ratio of 1:1 to 29:1, or water. The inert atmosphere is nitrogen or argon; The photochemical reactor is either a photochemical reactor equipped with a Xe lamp or a parallel photochemical reactor equipped with an LED light source; The reduction product is a formate.

[0012] (2) Determination of formic acid / formate: After the reaction is completed, the reaction solution is taken out from the reaction tube and filtered with an organic filter membrane. All solvents are removed by vacuum distillation. After being diluted with ultrapure water, ion chromatography is performed. The concentration of formic acid / formate is obtained based on the peak area and the formic acid standard curve.

[0013] (3) Catalytic activity r m Measurement: The level of catalytic activity of heterogeneous photocatalytic CO2 reduction is usually measured by the amount of product that can be generated per gram of catalyst per unit time.

[0014] Calculation formula: r m = Conc.(HCOO - ): Concentration of formic acid / formate produced, mol / L; V(HCOO - ): Volume of the solution after the reaction, in liters (L); m(Cat.): Mass of catalyst used, in grams; t: reaction time, h.

[0015] The beneficial effects of this invention are as follows: This invention designs and constructs a novel amide-type iridium-based Zn-based metal-organic framework for the first time. This metal-organic framework is a novel crystalline porous catalytic framework that has not been previously reported. Its unique and novel structure, along with the mild, simple, and controllable process of modifying the Zn-MOF support using amide-type ligands, allows for precise anchoring and uniform dispersion of the Ir metal active center, achieving innovative functional modification of the Zn-MOF support at the molecular level. The amide-type N,N bidentate coordination sites formed by covalent modification with pyridinecarboxylic acid effectively inhibit the recombination of photogenerated electrons and holes, promote directional electron migration, and significantly improve visible light utilization and CO2 adsorption activation capacity. It exhibits excellent performance in the photocatalytic reduction of CO2 to formic acid, with catalytic activity approximately four times higher than that of the unmodified Zn-MOF support. Simultaneously, the novel framework structure endows the catalyst with excellent structural stability and recyclability. The reaction conditions are mild, green, and efficient, possessing the dual value of emission reduction and high-value-added product preparation, and demonstrating promising industrial application prospects. Attached Figure Description

[0016] Figure 1 This is a field emission scanning electron microscope (SEM) spectrum of Ir@Zn-MOF-1 prepared in Example 1 of this invention.

[0017] Figure 2The images show the XRD patterns of the Zn-MOF supports, Ir@Zn-MOF-1, Ir@Zn-MOF-2 and Ir@Zn-MOF-3 prepared in Examples 1-4 of this invention.

[0018] Figure 3 shows the solid-state photoluminescence (PL) spectra of the Zn-MOF supports, Ir@Zn-MOF-1, Ir@Zn-MOF-2 and Ir@Zn-MOF-3 prepared in Examples 1-4 of this invention.

[0019] Figure 4 This is a comparison chart of the catalytic activities of four catalysts in Examples 1-3 of the present invention and those supported by Zn-MOF under the same reaction conditions. Detailed Implementation

[0020] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings and technical solutions.

[0021] Example 1 The preparation of Ir@Zn-MOF-1 and its application in photocatalytic CO2 reduction are as follows: (1) Weigh terephthalic acid (47.6 mg, 0.2 mmol), zinc nitrate hexahydrate (59.4 mg, 0.2 mmol), and 3,5-diamino-1,2,4-triazole (19.8 mg, 0.2 mmol) and place them in a 50 mL round-bottom flask. Add 8 mL of N,N-dimethylformamide and 6 mL of deionized water, and stir the reaction for 24 h. Cool to room temperature, centrifuge to collect the solid, and wash it successively with dichloromethane and anhydrous methanol. Filter under reduced pressure to obtain the final product, place it in an 80 °C vacuum oven, and vacuum dry for 24 h to obtain Zn-MOF support with a yield of 72.0 mg.

[0022] (2) Accurately weigh the above Zn-MOF support (32.0 mg, 0.10 mmol) and place it in a 50 mL standard-mouth round-bottom flask. Add 2-pyridinecarboxylic acid (27.08 mg, 0.22 mmol), HOBt (41.47 mg, 0.22 mmol), and EDCI (58.83 mg, 0.22 mmol) in sequence. Add 15 mL of dichloromethane as solvent and stir the reaction at room temperature for 24 h. After the reaction is completed, cool naturally to room temperature, wash with N,N-dimethylformamide and methanol by centrifugation, collect the solid particles, filter under reduced pressure, and place the product in an 80 °C vacuum oven to dry for 24 h to obtain 40.85 mg of Zn-MOF-1 material.

[0023] (3) The Zn-MOF-1 carrier (53 mg), dichloro(pentamethylcyclopentadiene)iridium(III) dimer ([Cp IrCl2]2 (21.0 mg, 0.026 mmol) was dissolved in 10 mL of anhydrous methanol, substituted with N2 three times, and then heated to 65 °C for 24 h. After cooling to room temperature, the solid particles were collected by centrifugation and then repeatedly washed with anhydrous MeOH. The final product was obtained by vacuum filtration and placed in an 80 °C vacuum oven for vacuum drying for 24 h to obtain Ir@Zn-MOF-1 with a yield of 40.25 mg.

[0024] (4) Under N2 protection, an acetonitrile / water mixture (15 mL, v / v = 14:1) was added to the photoreaction tube, followed by the addition of Ir@Zn-MOF-1 (10 mg) and BIH (30 mg, 0.134 mmol), and the tube was sealed. The tube was replaced three times with high-purity CO2 for 30 min each time. Finally, the tube was placed in a parallel photoreactometer with an 18 W LED light source (λ ≥ 420 nm) and stirred at room temperature for 8 h. The concentration of the sacrificial agent BIH was 0.0089 mol / L, and the molar ratio of the metal-organic framework supported catalyst to the sacrificial agent was 1:13.4. After the reaction, 624.4 μmol of formic acid was generated, and the catalyst activity was 325.4 μmol·g. -1 ·h -1 .

[0025] Example 2 The preparation of Ir@Zn-MOF-2-A and its application in photocatalytic CO2 reduction are as follows: (1) The preparation process of Zn-MOF support is the same as step (1) in Example 1.

[0026] (2) Accurately weigh the above Zn-MOF support (32.0 mg, 0.10 mmol) and place it in a 50 mL standard-mouth round-bottom flask. Add 6-methoxypyridine-2-carboxylic acid (33.69 mg, 0.22 mmol), HOBt (41.47 mg, 0.22 mmol), and EDCI (58.83 mg, 0.22 mmol) in sequence. Add 15 mL of dichloromethane as a solvent. Seal the reaction system and stir at room temperature for 24 h. After the reaction is complete, cool naturally to room temperature. Wash with N,N-dimethylformamide and methanol by centrifugation, collect the solid particles, filter under reduced pressure, and place the product in an 80 °C vacuum oven to dry for 24 h to obtain 51.4 mg of Zn-MOF-2 material.

[0027] (3) Zn-MOF-2 carrier (74.3 mg), dichloro(pentamethylcyclopentadiene)iridium(III) dimer ([Cp IrCl2]2 (39.8 mg, 0.05 mmol) was dissolved in 10 mL of anhydrous methanol, substituted with N2 three times, and then heated to 65 °C for 24 h. After cooling to room temperature, the solid particles were collected by centrifugation and then repeatedly washed with anhydrous MeOH. The final product was obtained by vacuum filtration under reduced pressure and dried in an 80 °C vacuum oven for 24 h to obtain Ir@Zn-MOF-2 with a yield of 76.2 mg.

[0028] (4) Under an inert atmosphere (N2), the Ir@Zn-MOF-2 catalyst and the sacrificial agent BIH were dispersed in anhydrous acetonitrile solvent, then replaced with carbon dioxide multiple times, and finally placed in a parallel photochemical reactor equipped with an 18 W LED light source (λ ≥ 420 nm) and stirred for 8 hours; the concentration of the sacrificial agent BIH was 0.0089 mol / L, and the molar ratio of the metal-organic framework supported catalyst to the sacrificial agent was 1:13.4; after the reaction, 897.6 μmol formic acid was generated, and the catalyst activity was 424.4 μmol·g. -1 ·h -1 .

[0029] Example 3 The preparation of Ir@Zn-MOF-3 and its application in photocatalytic CO2 reduction are as follows: (1) The preparation process of Zn-MOF support is the same as step (1) in Example 1.

[0030] (2) Accurately weigh the above Zn-MOF support (32.0 mg, 0.10 mmol) and place it in a 50 mL standard-mouth round-bottom flask. Add 6-hydroxypyridine-2-carboxylic acid (30.6 mg, 0.22 mmol), HOBt (41.47 mg, 0.22 mmol), and EDCI (58.83 mg, 0.22 mmol) in sequence. Add 15 mL of dichloromethane as a solvent. Seal the reaction system and stir at room temperature for 24 h. After the reaction is complete, cool naturally to room temperature, centrifuge, wash with N,N-dimethylformamide and methanol, collect the solid particles, filter under reduced pressure, and place the product in an 80 °C vacuum oven to dry for 24 h to obtain 53.1 mg of Zn-MOF-3 material.

[0031] (3) The Zn-MOF-3 carrier (70.1 mg), dichloro(pentamethylcyclopentadiene)iridium(III) dimer ([Cp IrCl2]2 (21.0 mg, 0.026 mmol) was dissolved in 10 mL of anhydrous methanol, substituted with N2 three times, and then heated to 65 °C for 24 h. After cooling to room temperature, the solid particles were collected by centrifugation and then repeatedly washed with anhydrous MeOH. The final product was obtained by vacuum filtration and placed in an 80 °C vacuum oven for vacuum drying for 24 h to obtain Ir@Zn-MOF-3, with a yield of 69.2 mg.

[0032] (4) Under an inert atmosphere (N2), the Ir@Zn-MOF-3 catalyst and the sacrificial agent BIH were dispersed in anhydrous acetonitrile solvent, then replaced with carbon dioxide multiple times, and finally placed in a parallel photochemical reactor equipped with an 18 W LED light source (λ ≥ 420 nm) and stirred for 8 hours; the concentration of the sacrificial agent BIH was 0.0089 mol / L, and the molar ratio of the metal-organic framework supported catalyst to the sacrificial agent was 1:13.4; after the reaction, 759.3 μmol formic acid was generated, and the catalyst activity was 364.8 μmol·g. -1 ·h -1 .

[0033] Example 4 The preparation of Ir@Zn-MOF-2-B and its application in photocatalytic CO2 reduction are as follows: (1) Weigh terephthalic acid (47.6 mg, 0.2 mmol), zinc nitrate hexahydrate (59.4 mg, 0.2 mmol), and 3,5-diamino-1,2,4-triazole (19.8 mg, 0.2 mmol) and place them in a 50 mL round-bottom flask. Add 8 mL of N,N-dimethylformamide and 8 mL of deionized water, and stir the reaction for 48 h. Cool to room temperature, centrifuge to collect the solid, and wash it successively with dichloromethane and anhydrous methanol. After vacuum filtration, the final product is obtained and placed in an 80 °C vacuum oven for vacuum drying for 48 h to obtain Zn-MOF support with a yield of 71.3 mg.

[0034] (2) Accurately weigh the above Zn-MOF support (32.0 mg, 0.10 mmol) and place it in a 50 mL standard-mouth round-bottom flask. Add 6-methoxypyridine-2-carboxylic acid (33.69 mg, 0.22 mmol), HOBt (41.47 mg, 0.22 mmol), and EDCI (58.83 mg, 0.22 mmol) in sequence. Add 15 mL of dichloromethane as solvent and stir the reaction at room temperature for 48 h. After the reaction is completed, allow it to cool naturally to room temperature. Wash the solid particles with N,N-dimethylformamide and methanol by centrifugation, collect the solid particles, filter under reduced pressure, and place the product in an 80 °C vacuum oven to dry for 48 h to obtain 48.9 mg of Zn-MOF-2 material.

[0035] (3) The Zn-MOF-2 carrier (51.4 mg, 0.16 mmol), dichloro(pentamethylcyclopentadiene)iridium(III) dimer ([Cp IrCl2]2 (10.0 mg, 0.0125 mmol) was dissolved in 15 mL of anhydrous methanol, substituted with N2 three times, and then heated to 65 °C for 48 h. After cooling to room temperature, the solid particles were collected by centrifugation and then repeatedly washed with anhydrous MeOH. The final product was obtained by vacuum filtration under reduced pressure and dried in an 80 °C vacuum oven for 48 h to obtain Ir@Zn-MOF-2 with a yield of 65.8 mg.

[0036] (4) Under N2 protection, an acetonitrile / water mixture (15 mL, v / v = 14:1) was added to the photoreaction tube, followed by the addition of Ir@Zn-MOF-2 (10 mg) and BIH (30 mg, 0.134 mmol), and the tube was sealed. The tube was replaced three times with high-purity CO2 for 30 min each time. Finally, the tube was placed in a parallel photoreactometer with an 18 W LED light source (λ ≥ 420 nm) and stirred at room temperature for 10 h. The concentration of the sacrificial agent BIH was 0.0089 mol / L, and the molar ratio of the metal-organic framework supported catalyst to the sacrificial agent was 1:30. After the reaction, 895.3 μmol of formic acid was generated, and the catalyst activity was 423.1 μmol. · g -1 ·h -1 .

[0037] Example 5 The preparation of Ir@Zn-MOF-2-C and its application in photocatalytic CO2 reduction are as follows: (1) Weigh terephthalic acid (95.2 mg, 0.4 mmol), zinc nitrate hexahydrate (118.8 mg, 0.4 mmol), and 3,5-diamino-1,2,4-triazole (39.6 mg, 0.4 mmol) and place them in a 100 mL round-bottom flask. Add 16 mL of N,N-dimethylformamide and 12 mL of deionized water, and stir the reaction for 24 h (consistent with the reference group). Cool to room temperature, centrifuge to collect the solid, and wash it successively with dichloromethane and anhydrous methanol. After vacuum filtration, the final product is obtained and placed in an 80 °C vacuum oven for vacuum drying for 24 h to obtain Zn-MOF support with a yield of 289.5 mg.

[0038] (2) Accurately weigh the above Zn-MOF support (64.0 mg, 0.20 mmol) and place it in a 100 mL standard-mouth round-bottom flask. Add 6-methoxypyridine-2-carboxylic acid (67.38 mg, 0.44 mmol), HOBt (82.78 mg, 0.44 mmol), and EDCI (114.30 mg, 0.44 mmol) in sequence. Add 30 mL of dichloromethane as solvent and stir the reaction at room temperature for 24 h. After the reaction is completed, cool naturally to room temperature, wash with N,N-dimethylformamide and methanol by centrifugation, collect the solid particles, filter under reduced pressure, and place the product in an 80 °C vacuum oven to dry for 24 h to obtain 102.3 mg of Zn-MOF-2 material.

[0039] (3) The Zn-MOF-2 carrier (148.6 mg, 0.20 mmol), dichloro(pentamethylcyclopentadiene)iridium(III) dimer ([Cp IrCl2]2 (42.0 mg, 0.052 mmol) was dissolved in 30 mL of anhydrous methanol, substituted with N2 three times, and then heated to 65 °C for 24 h. After cooling to room temperature, the solid particles were collected by centrifugation and then repeatedly washed with anhydrous MeOH. The final product was obtained by vacuum filtration and placed in an 80 °C vacuum oven for vacuum drying for 24 h to obtain Ir@Zn-MOF-2 with a yield of 134.7 mg.

[0040] (4) Under N2 protection, an acetonitrile / water mixture (30 mL, v / v = 14:1) was added to the photoreaction tube, followed by the addition of Ir@Zn-MOF-2 (20 mg) and BIH (60 mg, 0.268 mmol), and the tube was sealed. The tube was replaced three times with high-purity CO2 for 30 min each time. Finally, the tube was placed in a parallel photoreactometer with an 18 W LED light source (λ ≥ 420 nm) and stirred at room temperature for 8 h. The concentration of the sacrificial agent BIH was 0.0089 mol / L, and the molar ratio of the metal-organic framework supported catalyst to the sacrificial agent was 1:13.4. After the reaction, 1792.8 μmol of formic acid was generated, and the catalyst activity was 424.0 μmol·g. -1 ·h -1 .

[0041] Example 6 The preparation of Ir@Zn-MOF-2-D and its application in photocatalytic CO2 reduction are as follows: This embodiment is based on Example 2, but adjusts the material ratio and solvent ratio for the synthesis of Zn-MOF support, the molar ratio of materials for the preparation of amide-type Zn-MOF-2 support, and the amount of material fed in the iridium metal loading step.

[0042] (1) Weigh terephthalic acid (47.6 mg, 0.2 mmol), zinc nitrate hexahydrate (118.8 mg, 0.4 mmol), and 3,5-diamino-1,2,4-triazole (39.6 mg, 0.4 mmol) into a 50 mL round-bottom flask; add 8 mL of N,N-dimethylformamide and 8 mL of deionized water; stir the reaction at 85 °C for 24 h under nitrogen protection. Cool to room temperature, collect the solid by centrifugation, and wash successively with dichloromethane and anhydrous methanol; filter under reduced pressure to obtain the final product, and dry it in a vacuum oven at 80 °C for 24 h to obtain Zn-MOF support with a yield of 143.8 mg.

[0043] (2) Accurately weigh the above Zn-MOF support (32.0 mg, 0.10 mmol) and place it in a 50 mL standard-mouth round-bottom flask. Add 6-methoxypyridine-2-carboxylic acid (61.25 mg, 0.40 mmol), HOBt (75.40 mg, 0.40 mmol), and EDCI (106.96 mg, 0.40 mmol) in sequence. Add 25 mL of dichloromethane as solvent, seal the reaction system, and stir the reaction at room temperature for 24 h. After the reaction is completed, cool naturally to room temperature, wash with N,N-dimethylformamide and methanol by centrifugation, collect the solid particles, filter under reduced pressure, and place the product in an 80 °C vacuum oven to dry for 24 h to obtain 50.2 mg of Zn-MOF-2 material.

[0044] (3) The Zn-MOF-2 carrier (148.6 mg), dichloro(pentamethylcyclopentadiene)iridium(III) dimer ([Cp IrCl2]2) (21.0 mg, 0.026 mmol) was dissolved in 20 mL of anhydrous methanol, substituted with N2 three times, and then heated to 65 °C for 24 h. After cooling to room temperature, the solid particles were collected by centrifugation and then repeatedly washed with anhydrous MeOH. The final product was obtained by vacuum filtration under reduced pressure and dried in an 80 °C vacuum oven for 24 h to obtain Ir@Zn-MOF-2 with a yield of 135.1 mg.

[0045] (4) Under an inert atmosphere (N2), Ir@Zn-MOF-2 catalyst (10 mg) and sacrificial agent BIH (30 mg, 0.134 mmol) were dispersed in anhydrous acetonitrile solvent. The concentration of sacrificial agent BIH was 0.016 mol / L, and the molar ratio of metal-organic framework supported catalyst to sacrificial agent was 1:13.4. Then, carbon dioxide was used to replace the catalyst three times for 30 min each time. Finally, the catalyst was placed in a parallel photochemical reactor equipped with an 18 W LED light source (λ ≥ 420 nm) and stirred at room temperature for 8 hours. After the reaction, 894.1 μmol formic acid was generated, and the catalyst activity was 422.5 μmol·g. -1 ·h -1 .

[0046] Example 7 The preparation of Ir@Zn-MOF-2-E and its application in photocatalytic CO2 reduction are as follows: This embodiment is based on Example 2, but adjusts the reaction time, catalyst and sacrificial agent dosage, and solvent system of the photocatalytic CO2 reduction step. The specific steps are as follows: (1) The preparation process of Zn-MOF support is the same as step (1) in Example 2.

[0047] (2) The preparation process of the amide-type Zn-MOF-2 support is the same as step (2) in Example 2.

[0048] (3) The preparation process of Ir@Zn-MOF-2 catalyst is the same as step (3) in Example 2.

[0049] (4) Under an inert atmosphere (N2), add acetonitrile / water mixed solution (15 mL, v / v = 29:1) to the photoreaction tube, then add Ir@Zn-MOF-2 (10 mg) and BIH (5 mg) to the photoreaction tube and seal the reaction tube. Replace with high-purity CO2 three times for 30 min each time. Finally, place the reaction tube in a parallel photoreactometer equipped with an 18 W LED light source (λ ≥ 420 nm) and stir the reaction at room temperature for 10 h; after the reaction, 276.3 μmol formic acid is generated, and the catalyst activity is 276.3 μmol·g. -1 ·h -1 .

Claims

1. A novel metal-organic framework supported catalyst, characterized in that, The structural formula of this novel metal-organic framework supported catalyst is as follows: 、 or ; The structural formula of the metal-organic framework carrier is as follows: 。 2. A method for preparing a novel metal-organic framework supported catalyst, characterized in that, Includes the following steps: (1) Synthesis of Zn-MOF support: Terephthalic acid, zinc nitrate hexahydrate and 3,5-diamino-1,2,4-triazole were dissolved in a mixed solvent of N,N-dimethylformamide and water, and then reacted under an inert atmosphere and at a certain temperature. After the reaction was completed, the mixture was centrifuged, washed with anhydrous methanol, and finally dried under reduced pressure to obtain Zn-MOF support. (2) Synthesis of amide-type Zn-MOF support: Zn-MOF support, pyridine carboxylic acid compound, 1-hydroxybenzotriazole (HOBt) and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDCI) were dissolved in dichloromethane and coupled at room temperature. After the reaction was completed, the mixture was centrifuged, washed with dichloromethane and methanol in sequence, ultrasonically dispersed, filtered, and dried at constant temperature to obtain amide-type Zn-MOF support. (3) Synthesis of amide-type iridium-based Zn-MOF catalyst: The amide-type Zn-MOF support and dichloro(pentamethylcyclopentadiene)iridium(III) dimer were dissolved in anhydrous methanol and reacted for 24 hours under an inert atmosphere and at 65°C. After cooling to room temperature, the solid particles were collected by centrifugation and then repeatedly washed with anhydrous methanol. After vacuum filtration, the catalyst was dried under vacuum to obtain a novel metal-organic framework supported catalyst.

3. The method for preparing the novel metal-organic framework supported catalyst according to claim 1, characterized in that, In step (1), The molar ratio of terephthalic acid, zinc nitrate hexahydrate, and 3,5-diamino-1,2,4-triazole is 1:1:1 to 1:2:2, and the concentrations of all three in the reaction system are 0.01-0.022 mol / L. The volume ratio of N,N-dimethylformamide to water in the mixed solvent is 1:1 to 4:3; The inert gas is nitrogen or argon; The specified temperature condition is 85℃; the reaction time is 24-48 hours. The vacuum drying temperature is 80℃; the vacuum drying time is 24-48 hours.

4. The method for preparing the novel metal-organic framework supported catalyst according to claim 1, characterized in that, In step (2), The molar ratio of Zn-MOF support, pyridine carboxylic acid compound, 1-hydroxybenzotriazole, and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride is 1:2.2:2.2:2.2-1:4:4:4; The concentration of pyridine carboxylic acid compounds in the reaction system was 0.012-0.018 mol / L; The pyridine carboxylic acid compounds are 2-pyridine carboxylic acid, 6-methoxypyridine-2-carboxylic acid, and 6-hydroxypyridine-2-carboxylic acid; The coupling reaction takes 24-48 hours; The constant temperature drying temperature is 80℃, and the time is 24-48 hours.

5. The method for preparing the novel metal-organic framework supported catalyst according to claim 1, characterized in that, In step (3), The concentration of the dichloro(pentamethylcyclopentadiene)iridium(III) dimer in the reaction system is 0.005-0.01 mol / L; The molar ratio of amide-type Zn-MOF support to dichloro(pentamethylcyclopentadiene)iridium(III) dimer is 4:1-2:1; The inert atmosphere is nitrogen or argon; The drying temperature is 80℃, and the drying time is 24-48 hours.

6. A method for photocatalytic CO2 reduction using a novel metal-organic framework supported catalyst, characterized in that, The steps are as follows: Photocatalytic CO2 reduction to formic acid: Under an inert atmosphere, a novel metal-organic framework supported catalyst and sacrificial agent are dispersed in a solvent, then replaced multiple times with carbon dioxide, and finally placed in a photochemical reactor and stirred for 2-10 hours to produce formate.

7. The method for photocatalytic CO2 reduction using the novel metal-organic framework supported catalyst according to claim 6, characterized in that, The sacrificial agent is one of 1,3-dimethyl-2-phenyl-2,3-dihydro-1H-benzo[d]imidazole (BIH), 1-benzyl-1,4-dihydronicotinamide (BNAH), triethanolamine (TEOA), and triethylamine (TEA); The concentration of the sacrificial agent in the reaction system was 0.004-0.016 mol / L; The molar ratio of novel metal-organic framework supported catalysts to sacrificial agents is 1:2 to 1:30; The solvent is one of the following: anhydrous acetonitrile, a mixed solution of acetonitrile and water in a volume ratio of 1:1 to 29:1, anhydrous N,N-dimethylformamide, a mixed solution of N,N-dimethylformamide and water in a volume ratio of 1:1 to 29:1, anhydrous N,N-dimethylacetamide, a mixed solution of N,N-dimethylacetamide and water in a volume ratio of 1:1 to 29:1, or water. The inert atmosphere is nitrogen or argon; The photochemical reactor is either a photochemical reactor equipped with a Xe lamp or a parallel photochemical reactor equipped with an LED light source.

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