A porous boron nitride-loaded copper nanomaterial and its preparation method and application

Abstract

The present invention belongs to the technical field of nanomaterial preparation, and particularly relates to a porous boron nitride-loaded copper nanomaterial and a preparation method thereof, as well as the application of the porous boron nitride-loaded copper nanomaterial as a catalyst in C-H activation / C-O coupling reaction. The material is a porous boron nitride nanomaterial with an active metal copper salt dispersed on the surface, wherein the active metal copper salt is dispersed on the surface of the material in the form of Cu4(SO4)(OH)6. The present invention prepares a novel porous boron nitride-loaded copper nanomaterial containing a copper base with high catalytic ability and having the characteristics of large specific surface area and multi-porosity. The copper salt loaded by the porous boron nitride-loaded copper nanomaterial has the characteristics of small particle size and uniform dispersion, and therefore has an excellent catalytic effect. Moreover, the porous boron nitride-loaded copper nanomaterial also has good structural stability, is easy to separate from an organic medium, and can be used as a catalyst for C-H activation / C-O coupling reaction.

Description

Technical Field

[0001] The present invention belongs to the technical field of nanomaterial preparation, and particularly relates to a porous boron nitride-supported copper nanomaterial and a preparation method thereof, as well as application of the porous boron nitride-supported copper nanomaterial as a catalyst in a CH activation / CO coupling reaction. Background Art

[0002] C-H bonds are present in almost all organic compounds and are a very common type of chemical bond. C-H bond activation is widely used in research fields such as organic synthesis, post-modification, and materials science. With the continuous development of C-H activation, CO coupling reactions have also become increasingly popular. As the most abundant chemical bond in nature, CO bonds are common in basic structural units of energy chemical industry, biomolecules, and medicinal chemistry. However, due to the shortcomings of traditional cross-coupling reactions, people have been exploring new methods for constructing CO bonds. Compared with Ullmann-type CO coupling reactions, C-H activation / CO coupling reactions eliminate the pre-functionalization step and have higher atom economy. More importantly, the byproducts of their reactions are theoretically more environmentally friendly than halides, which is beneficial to resource sustainability and environmental protection, and is in line with the current green chemistry initiative.

[0003] Pristine boron nitride nanomaterials are a class of nanomaterials with excellent properties, including high-temperature stability, chemical stability, low density, high permeability, and oxidative inertness. They are excellent metal catalyst supports, boasting large specific surface area, high porosity, and ease of functionalization, making them suitable for supporting various metal nanoparticles. The porous boron nitride-supported copper nanomaterial of the present invention not only shares the excellent properties of pristine boron nitride nanomaterials, but also features a dispersion and linkage of copper salt nanoparticles on the boron nitride surface, which positively impacts catalytic performance. The material is easily separated from the reaction and can be reused repeatedly. Summary of the Invention

[0004] The present invention aims to provide a porous boron nitride-supported copper nanomaterial and a preparation method thereof, as well as use of the porous boron nitride-supported copper nanomaterial as a catalyst in a CH activation / CO coupling reaction.

[0005] To achieve the above purpose, the present invention adopts the following technical solutions:

[0006] A porous boron nitride loaded copper nanomaterial, wherein active metal copper salt is dispersed on the surface of the porous boron nitride nanomaterial, wherein the active metal copper salt is dispersed on the surface of the material in the form of Cu4(SO4)(OH)6.

[0007] The loading amount of the active metal copper salt is 5-20% of the total mass of the porous boron nitride loaded copper nanomaterial.

[0008] A preparation method of the porous boron nitride-supported copper nanomaterial comprises hydroxylating hexagonal boron nitride under alkaline conditions and then reacting with CuSO4·5H2O to obtain a novel porous boron nitride-supported copper nanomaterial containing a copper base with high catalytic ability and having the characteristics of large specific surface area and multiple pores.

[0009] Specifically:

[0010] 1) Disperse hexagonal boron nitride in an alkaline solution and react at 80-85°C for 12-14 hours under magnetic stirring;

[0011] 2) filtering the suspension obtained in step 1) through a filter membrane, washing the filter cake with water until neutral, and drying the resulting filter cake at 60-70° C. for 24-30 hours to obtain hydroxylated hexagonal boron nitride;

[0012] 3) Dissolve CuSO4·5H2O in deionized water, add concentrated ammonia dropwise at 70-80°C with stirring until the generated light blue precipitate is completely dissolved, add the hydroxylated hexagonal boron nitride obtained in step 2), and continue stirring until a blue-green precipitate is generated;

[0013] 4) The suspension obtained in step 3) is filtered through a filter membrane, and the filter cake is washed with anhydrous ethanol and ether in sequence. The filter cake is dried at 60-70° C. for 24-30 hours to obtain a water-green porous boron nitride-loaded copper nanomaterial.

[0014] The mass ratio of the hydroxylated hexagonal boron nitride to CuSO4.5H2O is 1:2-1:3.

[0015] The material is a porous boron nitride-loaded copper nanomaterial that has been dried in an oven, has a particle size of 5-400 nm, and is dried at a temperature of 60°C.

[0016] The concentration of the concentrated ammonia water is 25%.

[0017] The carrier is a dried porous boron nitride-loaded copper nanomaterial, and the particle size thereof is 5-400 nm.

[0018] An application of the porous boron nitride-supported copper nanomaterial, and an application of the porous boron nitride-supported copper nanomaterial as a catalyst in a CH activation / CO coupling reaction.

[0019] When the reaction substrate is 1 mmol, the amount of the catalyst used is 15-20 mg.

[0020] The porous boron nitride-loaded copper nanomaterial prepared by the present invention is easily separated from the reaction system by conventional methods, such as centrifugation or filtration with filter paper. Therefore, copper salt nanoparticles are further loaded onto the surface of the porous boron nitride nanomaterial, resulting in not only a good catalytic effect but also easy separation from the reaction product after the catalytic reaction is completed. Experiments with CH activation and CO coupling reactions have confirmed that the catalyst prepared above indeed has a good catalytic effect and stability, and is easy to separate and reuse.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The porous boron nitride-loaded copper nanomaterial of the present invention has a simple preparation process, is easy to operate, and is suitable for large-scale production.

[0023] The porous boron nitride-supported copper nanocatalyst of the present invention has the characteristics of uniformly dispersed copper salt particles, extremely high copper atom utilization rate, and metal particles are not easy to agglomerate. It can be applied to the CH activation / CO coupling reaction and can effectively catalyze the coupling reaction under relatively mild conditions. It has the advantages of high activity, high selectivity, and the catalyst is stable and easy to recover. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 XRD patterns of Cu@BNNSs and pristine BNNSs-OH prepared in Example 1 of the present invention.

[0025] Figure 2 SEM images of Cu@BNNSs and pristine BNNSs-OH prepared in Example 1 of the present invention; wherein, A is the SEM image of pristine BNNSs-OH, and B is the SEM image of Cu@BNNSs.

[0026] Figure 3 TEM images of Cu@BNNSs prepared in Example 1 of the present invention; wherein, A is a TEM image taken at a scale of 200 nm, and B is a TEM image taken at a scale of 20 nm.

[0027] Figure 4 XPS graph of Cu@BNNSs prepared in Example 1 of the present invention; wherein A is the full-scan XPS spectrum of Cu@BNNSs, B is the high-resolution three-dimensional spectrum of Cu, and C is the high-resolution three-dimensional spectrum of B.

[0028] Figure 5 Cyclic catalytic test results of Cu@BNNSs prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0029] The present invention is described in detail below by specific examples, but these examples do not limit the content of the present invention. Meanwhile, the examples only provide some conditions for achieving this purpose, but do not mean that these conditions must be met to achieve this purpose.

[0030] The present invention discloses a novel porous boron nitride-supported copper nanomaterial containing a copper base with high catalytic activity, a large specific surface area, and high porosity. The copper salt supported by the porous boron nitride-supported copper nanomaterial has small particle size and uniform dispersion, thereby exhibiting excellent catalytic effects. Furthermore, the porous boron nitride-supported copper nanomaterial has good structural stability and is easily separated from organic media, making it suitable as a catalyst for CH activation / CO coupling reactions.

[0031] Example 1:

[0032] The porous boron nitride-loaded copper nanomaterials were prepared according to the following specific steps.

[0033] 1) Weigh 1.0 g of hexagonal boron nitride and disperse it in 250 mL of 5 mol / L NaOH aqueous solution. Incubate the mixture at 80°C for 12 h under magnetic stirring.

[0034] 2) The suspension obtained in step 1) was filtered through a filter membrane, and the filter cake was washed with water until neutral. The filter cake was dried at 65° C. for 24 h to obtain hydroxylated hexagonal boron nitride, which was designated as BNNSs-OH.

[0035] 3) Dissolve 3.1 g of CuSO4·5H2O in 25 mL of deionized water. Add 25% concentrated ammonia dropwise at 70°C with stirring until the resulting light blue precipitate is completely dissolved. Add the hydroxylated hexagonal boron nitride obtained in step 2) and continue stirring until a blue-green precipitate is formed.

[0036] 4) The suspension obtained in step 3) was filtered through a filter membrane, and the filter cake was washed with 10 mL of anhydrous ethanol and 2 mL of ether. The filter cake was dried at 65°C for 24 h to obtain a water-green porous boron nitride-supported copper nanomaterial, which was designated as Cu@BNNSs (see Figure 1-4 ).

[0037] The structural information and crystal phase of Cu@BNNSs and BNNSs-OH were analyzed by XRD. Figure 1As shown, Cu@BNNSs and BNNSs-OH exhibit characteristic peaks at 2θ = 26.62°, 41.46°, 43.76°, 49.92°, 55.08°, and 75.84°, which correspond to the boron nitride structure (JCPDS The (002), (100), (101), (102), (004) and (110) lattice planes of Pd-BNPs-1100 (JCPDS No. 34-0421) indicate that the crystal structure of boron nitride is not destroyed by the reaction. In the XRD pattern of Pd-BNPs-1100, clear new diffraction peaks appear at 2θ = 22.80°, 27.98°, 30.54°, 33.32°, 35.60°, 36.44°, 41.60°, 52.46°, 59.10° and 65.00°, which belong to the (310), (400), (230), (420), (-222), (510), (-232), (-442), (-802) and (830) lattice planes of Cu4(SO4)(OH)6 (JCPDS No. 43-1458), respectively. Depend on Figure 2 The SEM image shows that Cu@BNNSs is a sheet-like material. Figure 3 The TEM image shows that the copper salt is loaded on the surface of the BNNSs-OH material. The electronic information and existence state of copper in Cu@BNNSs were studied by XPS. Figure 4 The existing survey scanning XPS spectrum (A) shows that there are five sharp binding energy peaks in Cu@BNNSs, which belong to Cu, O, N, C and B respectively; and further high-resolution Cu three-dimensional spectrum has six binding energy peaks (B), of which 955.11, 959.20 and 962.51eV belong to Cu 2p 1 / 2 , 934.95, 940.55 and 943.52eV belong to Cu2p 3 / 2 ; At the same time, in the high-resolution three-dimensional spectrum of B (C), the binding energy peaks of 190.26 and 191.02 correspond to the BN and BO functional bonds, respectively.

[0038] Comparative Example 1: CuSO4·5H2O catalyzed CO coupling reaction of 2-phenylpyridine and ethylene glycol. The specific process and results are as follows:

[0039] Under normal pressure and air atmosphere, CuSO4·5H2O catalyst (40 mol%), 2-phenylpyridine (1.0 mmol), and ethylene glycol (3 ml) were added to a 20 mL sealed tube and stirred at 120°C. After 24 h, the reaction was post-processed and extracted with ethyl acetate and water. The ethyl acetate extract was washed with saturated brine, dried over anhydrous sodium sulfate, and filtered. The ethyl acetate was evaporated on a rotary evaporator to obtain a white solid, which was then purified by silica gel column chromatography to obtain the product 2-[2-(2-pyridyl)phenoxy]ethanol in a yield of 61%.

[0040] Application Example 2: Cu@BNNSs-catalyzed CO coupling reaction of 2-phenylpyridine and ethylene glycol. The specific process and results are as follows:

[0041] Under normal pressure air atmosphere, Cu@BNNSs catalyst (20 mg), 2-phenylpyridine (1.0 mmol), and ethylene glycol (3 ml) were added to a 20 mL sealed tube, and the reaction was stirred at 120°C. After 24 hours, post-reaction treatment was carried out, and the catalyst was recovered by filtration with a filter membrane. The separated material on the filter paper was washed with ethyl acetate, water, and ethyl acetate to obtain the catalyst. The separated catalyst was used for the next cyclic catalytic test; the filtrate was extracted with ethyl acetate and water; the ethyl acetate extract was washed with saturated brine, dried over anhydrous sodium sulfate, and filtered; the ethyl acetate was evaporated on a rotary evaporator to obtain a white solid, which was then purified by silica gel column chromatography to obtain the product 2-[2-(2-pyridyl)phenoxy]ethanol with a yield of 80%.

[0042] From the above application examples, it can be seen that the Cu@BNNSs catalyst has high reaction activity. The catalyst was recovered after the reaction and the cycle stability test was carried out. The results are as follows Figure 5 It can be seen that porous boron nitride-loaded copper nanomaterials have high activity and reactant stability.

[0043] In summary, the porous boron nitride-supported copper nanomaterial of the present invention, used as a catalyst for the CH activation / CO coupling reaction, provides an efficient and stable method for achieving CO coupling. The catalyst preparation process is simple and amenable to large-scale production. It possesses uniformly dispersed copper salt particles and extremely high copper atom utilization, enabling highly active catalysis of the CH activation / CO coupling reaction. Furthermore, the reaction process is environmentally friendly, and the catalyst is stable and easily recyclable.

[0044] The above embodiments are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. The scope of protection of the present invention shall be determined by the scope defined in the claims. Other variations or modifications may be made based on the above description. Obvious variations or modifications derived therefrom shall remain within the scope of protection of the present invention.

Claims

1. A porous boron nitride-loaded copper nanomaterial, characterized by: The material is a porous boron nitride nanomaterial with active metal copper salt dispersed on the surface, wherein the active metal copper salt is dispersed on the surface of the material in the form of Cu4(SO4)(OH)6.

2. The porous boron nitride-supported copper nanomaterial according to claim 1, characterized in that: The loading amount of the active metal copper salt is 5-20% of the total mass of the porous boron nitride loaded copper nanomaterial.

3. A method for preparing the porous boron nitride-supported copper nanomaterial according to claim 1, characterized in that: Hexagonal boron nitride is hydroxylated in alkaline conditions and then reacted with CuSO4·5H2O to obtain a novel porous boron nitride-loaded copper nanomaterial containing a copper base with high catalytic activity and having large specific surface area and multiple pores.

4. The method for preparing the catalyst according to claim 3, wherein: 1) Disperse hexagonal boron nitride in an alkaline solution and react at 80-85°C for 12-14 hours under magnetic stirring; 2) filtering the suspension obtained in step 1) through a filter membrane, washing the filter cake with water until neutral, and drying the resulting filter cake at 60-70° C. for 24-30 hours to obtain hydroxylated hexagonal boron nitride; 3) Dissolve CuSO4·5H2O in deionized water, add concentrated ammonia dropwise at 70-80°C with stirring until the generated light blue precipitate is completely dissolved, add the hydroxylated hexagonal boron nitride obtained in step 2), and continue stirring until a blue-green precipitate is generated; 4) The suspension obtained in step 3) is filtered through a filter membrane, and the filter cake is washed with anhydrous ethanol and ether in sequence. The filter cake is dried at 60-70° C. for 24-30 hours to obtain a water-green porous boron nitride-loaded copper nanomaterial.

5. The preparation method according to claim 4, characterized in that: The mass ratio of the hydroxylated hexagonal boron nitride to CuSO4.5H2O is 1:2-1:

3.

6. The preparation method according to claim 4, characterized in that: The material is a porous boron nitride-loaded copper nanomaterial that has been dried in an oven, has a particle size of 5-400 nm, and is dried at a temperature of 60°C.

7. An application of the porous boron nitride-supported copper nanomaterial according to claim 1, characterized in that: The porous boron nitride-supported copper nanomaterial is used as a catalyst in a CH activation / CO coupling reaction.

8. The use according to claim 7, characterized in that: When the reaction substrate is 1 mmol, the amount of the catalyst used is 15-20 mg.

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