Preparation and application of a MOF / CdZnS composite material

Abstract

The invention discloses a MOF / Cd x Zn 1‑x The invention discloses a preparation method and application of a MOF / Cd S composite material, which belongs to the field of photocatalytic material preparation. x Zn 1‑x S composite material, which is simple, cost-effective, environmentally friendly, easy to promote on a large scale, and the obtained MOF / Cd x Zn 1‑x The S composite material has a lamellar stacking morphology and can photocatalyze the selective oxidation of benzyl alcohol to produce hydrogenated benzoin under visible light irradiation, and synergistically produce hydrogen. Therefore, it can not only meet the sustainable development needs of green synthesis, but also simultaneously obtain high value-added industrial products and clean hydrogen energy, and has good application prospects.

Description

Technical Field

[0001] The present invention belongs to the field of photocatalytic material preparation, and specifically relates to a MOF / Cd x Zn 1-x Preparation method and application of S composite material. Background Art

[0002] Hydrogenated benzoin is an important organic synthesis intermediate and fine chemical product. It can be used as a chiral auxiliary, structural unit and chiral ligand. It is widely used in the pharmaceutical, dye and other industries. It can be synthesized by oxidation of benzyl alcohol. However, traditional oxidation methods often need to be carried out under harsh conditions such as high temperature, high pressure, strong acid and strong alkali. It not only consumes energy but also may cause environmental pollution, which is not in line with the concept of green environmental protection. Photocatalytic oxidation of benzyl alcohol to produce hydrogenated benzoin is a green synthesis method with simple process and green environmental protection. It can not only use solar energy to photocatalyze the oxidation of benzyl alcohol to produce hydrogenated benzoin, but also obtain clean and efficient hydrogen energy. Solid solution sulfide Cd x Zn 1-x S is a visible light photocatalyst with easy-to-obtain raw materials and simple preparation methods. Its valence band potential can oxidize benzyl alcohol to produce hydrogenated benzoin, but Cd x Zn 1-x The high recombination rate of photogenerated carriers in S limits its practical application. x Zn 1-x The application of S-based materials in visible light-photocatalytic benzyl alcohol oxidation coupled with hydrogen production is of great significance for the green synthesis of high value-added organic compounds. Summary of the invention

[0003] In view of the shortcomings of the prior art, the present invention aims to provide a MOF / Cd x Zn 1-x The preparation method and application of MOF / Cd S composite material are simple, cost-effective, environmentally friendly, and easy to promote on a large scale. x Zn 1-x The S composite material has the advantages of high photocatalytic activity, high selectivity and good stability, and can be applied to the visible light light catalytic oxidation coupling of benzyl alcohol to produce hydrogen.

[0004] To achieve the above object, the present invention adopts the following technical solution:

[0005] A MOF / Cd x Zn 1-x A method for preparing a composite material of metal organic framework material MOF and solid solution sulfide Cd x Zn 1-x S was synthesized by electrostatic self-assembly; specifically, a certain amount of MOF and Cd x Zn1-x S was dispersed in a mixed solution of deionized water and anhydrous ethanol (2:1, v / v), and stirred in a constant temperature oil bath at 60-100 °C for 3-5 h to obtain the MOF / Cd x Zn 1-x S composite material.

[0006] Furthermore, the MOF and Cd x Zn 1-x The mass ratio of S is (0.05~0.65):1.

[0007] Furthermore, the MOF is any one of Ni-MOF-74, MIL-53(Fe), and ZIF-67.

[0008] Furthermore, the Cd x Zn 1-x S is synthesized by a solvothermal method using a cadmium source, a zinc source and a sulfur source as raw materials. Specifically, the cadmium source and the zinc source are dispersed in a mixed solution of deionized water and ethylenediamine (1:1, v / v) in the required proportion, stirred for 0.5 h, and then the sulfur source is added. After continuing to stir for 0.5 h, the dispersion is transferred to a high-pressure reactor and reacted at a constant temperature of 150-180°C for 10-24 h to obtain the product.

[0009] Wherein, the cadmium source is any one of cadmium acetate, cadmium nitrate and cadmium chloride, the zinc source is any one of zinc acetate, zinc nitrate and zinc chloride, and the sulfur source is any one of thioacetamide, sodium sulfide and thiourea.

[0010] MOF / Cd prepared by the above method x Zn 1-x The S composite material can be used in the visible light-photocatalytic benzyl alcohol oxidation coupled with hydrogen production reaction.

[0011] The significant advantages of the present invention are:

[0012] (1) The MOF / Cd synthesized by the electrostatic self-assembly method x Zn 1-x The S composite material has excellent photocatalytic activity and stability. It can catalyze the selective oxidation of benzyl alcohol to produce hydrogenated benzoin in an acetonitrile solvent system under visible light irradiation, and can reduce protons to produce H2.

[0013] (2) The preparation method of the present invention is simple to operate, low in cost, environmentally friendly, and has no harsh operating environment requirements, which is conducive to large-scale promotion. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 The Cd prepared in Example 1 0.7 Zn 0.3S, Ni-MOF-74 and Ni-MOF-74 / Cd 0.7 Zn 0.3 X-ray powder diffraction pattern of S;

[0015] Figure 2 The Cd prepared in Example 1 0.7 Zn 0.3 S(a), Ni-MOF-74(b) and Ni-MOF-74 / Cd 0.7 Zn 0.3 SEM image of S (c);

[0016] Figure 3 The Cd prepared in Example 1 0.7 Zn 0.3 S, Ni-MOF-74 and Ni-MOF-74 / Cd 0.7 Zn 0.3 UV-visible absorption spectrum of S;

[0017] Figure 4 The Cd prepared in Example 1 0.7 Zn 0.3 S, Ni-MOF-74 and Ni-MOF-74 / Cd 0.7 Zn 0.3 Activity comparison of S photocatalytic benzyl alcohol oxidation coupled to hydrogen production;

[0018] Figure 5 The Ni-MOF-74 / Cd prepared in Example 1 0.7 Zn 0.3 S shows the stability results of the visible light-photocatalytic benzyl alcohol oxidation coupled with hydrogen production. DETAILED DESCRIPTION

[0019] In order to make the contents of the present invention easier to understand, the technical solution of the present invention is further described below in conjunction with specific implementation methods, but the present invention is not limited thereto.

[0020] Example 1: Ni-MOF-74 / Cd 0.7 Zn 0.3 Preparation of S composite materials

[0021] 1) Weigh 1.6791 g of cadmium acetate and 0.5927 g of zinc acetate, disperse them in a mixed solution of 30 mL of deionized water and 30 mL of ethylenediamine, stir for 0.5 h, then add 1.8783 g of thioacetamide, continue stirring for 0.5 h, transfer the dispersion to a 100 mL autoclave, keep the reaction at 180 °C for 24 h, cool to room temperature naturally, wash with ethanol and deionized water until the ion concentration is <10 ppm, and dry at 60 °C for 24 h to obtain yellow Cd0.7 Zn 0.3 S powder;

[0022] 2) Weigh 1.60 g nickel nitrate hexahydrate, 0.48 g terephthalic acid, and 2.40 g polyvinyl pyrrolidone, dissolve in 20 mL deionized water, 20 mL anhydrous ethanol, and 20 mL N,N-dimethylformamide, stir for 1 h, then transfer the mixed solution into a 100 mL high-pressure reactor, keep the reaction at 150 ° C for 10 h, and after naturally cooling to room temperature, wash the resulting mixture with ethanol and deionized water until the ion concentration is <10 ppm, and dry at 60 ° C for 24 h to obtain green Ni-MOF-74 powder;

[0023] 3) Weigh 0.0175 g Ni-MOF-74 and 0.1 g Cd 0.7 Zn 0.3 S was dispersed in a mixed solution of 40 mL deionized water and 20 mL anhydrous ethanol, stirred in an 80 °C constant temperature oil bath for 3.5 h, and after the solvent evaporated, dried at 60 °C for 24 h to obtain the composite material Ni-MOF-74 / Cd 0.7 Zn 0.3 S.

[0024] Figure 1 The Cd prepared in Example 1 0.7 Zn 0.3 S, Ni-MOF-74 and Ni-MOF-74 / Cd 0.7 Zn 0.3 X-ray powder diffraction pattern of S. As can be seen from the figure, the prepared Cd 0.7 Zn 0.3 S is cubic, while Ni-MOF-74 / Cd 0.7 Zn 0.3 The S composites can be observed to be attributed to the cubic Cd 0.7 Zn 0.3 Characteristic diffraction peaks of S and Ni-MOF-74.

[0025] Figure 2 The Cd prepared in Example 1 0.7 Zn 0.3 S(a), Ni-MOF-74(b) and Ni-MOF-74 / Cd 0.7 Zn 0.3 S (c) SEM image. As shown in the figure, Cd 0.7 Zn 0.3 S is an irregular particle with a diameter of about 100 nm, and Ni-MOF-74 is a sheet-like stacked structure with a side length of about 10 μm. The composite material is characterized by Cd uniformly distributed on Ni-MOF-74. 0.7Zn 0.3 S particles.

[0026] Figure 3 The Cd prepared in Example 1 0.7 Zn 0.3 S, Ni-MOF-74 and Ni-MOF-74 / Cd 0.7 Zn 0.3 UV-visible absorption spectrum of S. As shown in the figure, the composite material Ni-MOF-74 / Cd 0.7 Zn 0.3 S and Cd 0.7 Zn 0.3 There is no obvious difference in the photoresponse spectra of S, and the absorption band edges are all around 500 nm.

[0027] Application Example 1 Testing of the performance of visible light catalytic benzyl alcohol oxidation coupled hydrogen production

[0028] The Cd prepared in Example 1 0.7 Zn 0.3 S, Ni-MOF-74 and Ni-MOF-74 / Cd 0.7 Zn 0.3 The S composite material was used for visible light catalytic benzyl alcohol oxidation coupling hydrogen production. The reaction was carried out in a closed system with a reactor volume of about 15 mL. A 300 W xenon lamp equipped with a 400 nm filter was used as the light source. 10 mg of the sample was weighed and placed in the reactor. 10 mL of acetonitrile was added, and 100 μL of benzyl alcohol was added dropwise. The reaction system was magnetically stirred and sealed with vacuum grease. Condensed water was passed to keep the temperature of the reaction system at 20 °C. High-purity argon was continuously passed for 0.5 h to exclude air, and then the vent valve was closed. After 3 h of illumination, quantitative sampling was performed. The product was detected by gas chromatography and liquid chromatography. The results are shown as follows: Figure 4 .

[0029] Figure 4 The Cd prepared in Example 1 0.7 Zn 0.3 S, Ni-MOF-74 and Ni-MOF-74 / Cd 0.7 Zn 0.3 Comparison of the photocatalytic activity of benzyl alcohol oxidation coupled to hydrogen production. 0.7 Zn 0.3 The yield of hydrogenated benzoin catalyzed by S composite material was 3.8 mmol g -1 h -1 The yield of benzaldehyde was 0.08 mmol g -1 h -1 The hydrogen production rate reached 3.74 mmol g -1 h -1, with a selectivity of up to 95%. Under the same conditions, no product was detected in Ni-MOF-74, and Cd 0.7 Zn 0.3 The yield of benzaldehyde catalyzed by S was 0.35 mmol g -1 h -1 The hydrogen production rate is 0.341 mmol g -1 h -1 , indicating that Ni-MOF-74 / Cd 0.7 Zn 0.3 The S composite material has excellent photocatalytic activity for benzyl alcohol oxidation coupled hydrogen production.

[0030] Application Example 2 Stability test of visible light catalytic benzyl alcohol oxidation coupled hydrogen production

[0031] The photocatalytic benzyl alcohol oxidation coupled hydrogen production activity experiment of Application Example 1 was tested for 5 cycles, that is, after one reaction, the catalyst was filtered and dried to recover, and the next round of reaction was carried out, and the test was continued for 5 times. The results are as follows: Figure 5 .

[0032] Figure 5 The Ni-MOF-74 / Cd prepared in Example 1 0.7 Zn 0.3 The stability results of the visible light-photocatalytic benzyl alcohol oxidation coupled hydrogen production are shown in the figure. As shown in the figure, after a total reaction time of 15 h, Ni-MOF-74 / Cd 0.7 Zn 0.3 The S composite material still retains a high catalytic activity, indicating that it has good stability.

[0033] Example 2: MIL-53(Fe) / Cd 0.8 Zn 0.2 Preparation of S composite materials

[0034] 1) Weigh 1.9190 g of cadmium acetate and 0.3951 g of zinc acetate, disperse them in a mixed solution of 30 mL of deionized water and 30 mL of ethylenediamine, stir for 0.5 h, then add 1.8783 g of thioacetamide, continue stirring for 0.5 h, transfer the dispersion to a 100 mL autoclave, keep the reaction at 180 °C for 24 h, cool to room temperature naturally, wash with ethanol and deionized water until the ion concentration is <10 ppm, and dry at 60 °C for 24 h to obtain yellow Cd 0.8 Zn 0.2 S powder;

[0035] 2) Weigh 0.2700 g of ferric chloride and 0.1660 g of terephthalic acid, disperse them in 5 mL of N, N-dimethylformamide, stir them magnetically for 0.5 h, transfer them to a 20 mL high-pressure reactor, and keep them at 150 °C for 12 h. After naturally cooling to room temperature, the resulting mixture is washed with ethanol and deionized water until the ion concentration is <10 ppm, and dried at 60 °C for 24 h to obtain yellow MIL-53(Fe) powder;

[0036] 3) Weigh 0.010 g MIL-53(Fe) and 0.1 g Cd 0.8 Zn 0.2 S was dispersed in a mixed solution of 40 mL deionized water and 20 mL anhydrous ethanol, stirred in a constant temperature oil bath at 60 °C for 5 h, and after the solvent evaporated, dried at 60 °C for 24 h to obtain the composite material MIL-53(Fe) / Cd 0.8 Zn 0.2 S.

[0037] Example 3: ZIF-67 / Cd 0.9 Zn 0.1 Preparation of S composite materials

[0038] 1) Weigh 2.1588 g of cadmium acetate and 0.1976 g of zinc acetate, disperse them in a mixed solution of 30 mL of deionized water and 30 mL of ethylenediamine, stir for 0.5 h, then add 1.8783 g of thioacetamide, continue stirring for 0.5 h, transfer the dispersion to a 100 mL autoclave, keep the reaction at 180 °C for 24 h, cool to room temperature naturally, wash with ethanol and deionized water until the ion concentration is <10 ppm, and dry at 60 °C for 24 h to obtain yellow Cd 0.9 Zn 0.1 S powder;

[0039] 2) Weigh 2.3282 g of cobalt nitrate in 180 mL of methanol (liquid A) and stir for 10 min. Weigh 2.6272 g of 2-methylimidazole in 140 mL of methanol (liquid B) and stir for 10 min. Quickly inject liquid B into liquid A. After standing at room temperature for 24 h, wash with methanol until the ion concentration is <10 ppm. Dry at 60 °C for 24 h to obtain purple ZIF-67 powder.

[0040] 3) Weigh 0.020 g ZIF-67 and 0.1 g Cd 0.9 Zn 0.1 S was dispersed in a mixed solution of 40 mL deionized water and 20 mL anhydrous ethanol, stirred in a constant temperature oil bath at 70 °C for 4 h, and then dried at 60 °C for 24 h to obtain the composite material ZIF-67 / Cd0.9 Zn 0.1 S.

[0041] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made according to the scope of the patent application of the present invention should fall within the scope of the present invention.

Claims

1. A MOF / Cd x Zn 1-x The preparation method of S composite material is characterized by: The MOF / Cd x Zn 1-x The S composite material is composed of metal organic framework material MOF and solid solution sulfide Cd x Zn 1-x S was synthesized by electrostatic self-assembly; specifically, a certain amount of MOF and Cd x Zn 1-x S was dispersed in a mixed solution of deionized water and anhydrous ethanol and stirred for 3 to 5 h in a constant temperature oil bath at 60 to 100 °C to obtain the MOF / Cd x Zn 1-x S composite material; MOF and Cd x Zn 1-x The mass ratio of S is (0.05~0.65):1,0≤x≤1; The Cd x Zn 1-x S is synthesized by a solvothermal method using a cadmium source, a zinc source and a sulfur source as raw materials, and specifically, the cadmium source and the zinc source are dispersed in a mixed solution of deionized water and ethylenediamine according to the required proportion, stirred for 0.5 h, and then the sulfur source is added, and the dispersion is transferred to a high-pressure reactor after stirring for 0.5 h, and the reaction is carried out at a constant temperature of 150-180°C for 10-24 h to obtain the obtained product; MOF / Cd prepared by the above method x Zn 1-x The S composite material can be used in the visible light photocatalytic benzyl alcohol oxidation coupled with hydrogen production reaction.

2. MOF / Cd according to claim 1 x Zn 1-x The preparation method of S composite material is characterized by: The MOF is any one of Ni-MOF-74, MIL-53(Fe), and ZIF-67.

3. MOF / Cd according to claim 1 x Zn 1-x The preparation method of S composite material is characterized by: The volume ratio of deionized water to anhydrous ethanol in the mixed solution is 2:1.

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