A copper atomic-level dispersed catalyst and its preparation method and application

Abstract

The present application belongs to the technical field of copper catalysts, and in particular, relates to a copper atomic-level dispersed catalyst, a preparation method and an application thereof; the copper atomic-level dispersed catalyst provided by the present application uses carbon nanotubes as a carrier to load copper single atoms, and in the process of catalytic synthesis of chiral dinaphthol, the copper single atom active center can fully participate in the reaction of catalytic synthesis of chiral dinaphthol, thereby improving the catalytic effect of the catalyst; and the copper atomic-level dispersed catalyst provided by the present application can be recovered and reused, and the copper atomic-level dispersed catalyst has good catalytic stability, thereby solving the technical problem that the copper catalyst provided in the prior art has a low effect in catalytic synthesis of chiral dinaphthol molecules.

Description

Technical Field

[0001] The present application belongs to the technical field of copper catalysts, and in particular relates to a copper atomic-level dispersed catalyst and a preparation method and application thereof. Background Art

[0002] The two naphthalene rings in the chiral binaphthol (BINOLs) molecule are not coplanar. It is a typical chiral compound with a C2-symmetry axis and has a strong chiral induction effect. As a multifunctional chiral auxiliary and ligand in organic synthesis, it can induce the configuration of new asymmetric carbon atoms and generate unequal amounts of stereoisomers. At the same time, chiral binaphthol (BINOLs) molecules are needed in the preparation of second nonlinear optics and organic light-emitting devices (OLEDs). Chiral binaphthol (BINOLs) molecules are also needed in nuclear magnetic resonance spectroscopy (NMR), high performance liquid chromatography (HPLC), X-ray crystallography and electrochemistry in the process of enantioselective molecular recognition. Chiral binaphthol (BINOLs) molecules are important chiral raw materials.

[0003] At present, the catalysts used in the catalytic synthesis of chiral binaphthol (BINOLs) molecules are mainly precious metal catalysts such as platinum and cheap metal catalysts such as copper. Copper catalysts are inexpensive, which is conducive to the large-scale catalytic synthesis of chiral binaphthol (BINOLs) molecules. However, among the copper catalysts currently used, there are not many copper active centers directly involved in the reaction, and most of the copper active centers are unable to participate in the reaction at the bottom layer. At the same time, copper catalysts are difficult to separate, recover and regenerate after the reaction, which limits the effect of copper catalysts in catalyzing the synthesis of chiral binaphthol (BINOLs) molecules. Summary of the invention

[0004] In view of this, the present application provides a copper atomic-level dispersed catalyst and a preparation method and application thereof, which are used to solve the technical problem that the copper catalyst provided in the prior art has a low effect in catalyzing the synthesis of chiral dinaphthol molecules.

[0005] In a first aspect, the present application provides a copper atomic-level dispersed catalyst, comprising carbon nanotubes and copper single atoms;

[0006] The carbon nanotubes support the copper single atoms.

[0007] Preferably, the mass ratio of the carbon nanotubes to the copper atoms is 500:0.25-2.5.

[0008] The second aspect of the present application provides a method for preparing a copper atomic-level dispersed catalyst, which can be used to prepare the copper atomic-level dispersed catalyst described in the first aspect. The preparation method comprises the steps of:

[0009] Step S1, adding carbon nanotubes into a Cu-EDTA solution and stirring until the solvent is completely evaporated, and drying to obtain a copper atomic-level dispersed catalyst precursor;

[0010] Step S2, calcining the copper atomic-level dispersed catalyst precursor at high temperature to obtain the copper atomic-level dispersed catalyst.

[0011] Preferably, in step S1, the amount of the carbon nanotubes is 500 mg, the concentration of the Cu-EDTA solution is 5-15 mg / ml, and the amount is 100-300 µl.

[0012] Preferably, in step S1, the temperature during the stirring process is 80-120°C.

[0013] Preferably, in step S2, the atmosphere for high-temperature calcination is nitrogen, the heating rate is 5°C / min, the holding time is 600-800°C, and the time is 2-4h.

[0014] The third aspect of the present application provides an application of a copper atomic-level dispersed catalyst in the catalytic synthesis of chiral binaphthol.

[0015] Preferably, the application specifically includes:

[0016] The copper atomic-level dispersed catalyst described in the first aspect catalyzes an asymmetric reaction of β-naphthol to synthesize chiral binaphthol.

[0017] Preferably, in the asymmetric reaction, the reaction atmosphere is oxygen, the reaction pressure is 0.2-0.8 MPa, the reaction temperature is 50-90° C., and the reaction time is 16-32 h.

[0018] Preferably, in the asymmetric reaction, the ratio of the copper atomic-level dispersed catalyst to the β-naphthol is 800 mg: 10-50 mmol.

[0019] In summary, the present application provides a copper atomic-level dispersed catalyst and a preparation method and application thereof. The copper atomic-level dispersed catalyst provided by the present application utilizes a carbon nanotube carrier to load copper single atoms, and the copper single atom active center is stably dispersed at the atomic level, which fully enables the copper active center to catalyze the synthesis of chiral binaphthol (BINOLs) molecules. At the same time, the carbon nanotube carrier can remain stable under conditions of high temperature, high pressure, etc., which is conducive to the separation and reuse of the catalyst, and the carbon nanotube can avoid the influence of salt or impurity elements on the catalytic synthesis of chiral binaphthol molecules. Therefore, the copper atomic-level dispersed catalyst provided by the present application can improve the effect of the catalyst in catalyzing the synthesis of chiral binaphthol (BINOLs) molecules, and can solve the technical problem that the copper catalyst provided in the prior art has a low effect in catalyzing the synthesis of chiral binaphthol molecules. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the specific implementation methods of the present application or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0021] Figure 1 This is a high-angle annular dark field image-scanning transmission electron microscope image of the copper atomic-level dispersed catalyst provided in Example 1 of the present application;

[0022] Figure 2 This is an X-ray extension diagram of the copper atomic-level dispersed catalyst provided in Example 1 of the present application;

[0023] Figure 3 A schematic diagram of a chiral binaphthol molecule catalyzed and synthesized by the copper atomic-level dispersed catalyst provided in Example 1 of the present application;

[0024] Figure 4 A synthetic route for chiral binaphthol molecules synthesized by the copper atomic-level dispersed catalyst provided in Example 1 of the present application;

[0025] Figure 5 The nuclear magnetic resonance hydrogen spectrum of the chiral binaphthol molecule synthesized by the copper atomic-level dispersed catalyst provided in Example 1 of the present application;

[0026] Figure 6 This is the carbon nuclear magnetic resonance spectrum of the chiral binaphthol molecule catalytically synthesized by the copper atomic-level dispersed catalyst provided in Example 1 of the present application. DETAILED DESCRIPTION

[0027] The present application provides a copper atomic-level dispersed catalyst and a preparation method and application thereof, which are used to solve the technical problem that the copper catalyst provided in the prior art has a low effect in catalyzing the synthesis of chiral binaphthol molecules.

[0028] The technical solution of the present application will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present application.

[0029] In view of the fact that the copper catalyst currently used in the process of catalytic synthesis of chiral binaphthol (BINOLs) molecules has few copper active centers participating in the reaction, and the copper catalyst has a low effect in catalytic synthesis of chiral binaphthol molecules, the present application provides a copper atomic-level dispersed catalyst, which comprises carbon nanotubes and copper single atoms; the carbon nanotubes as a carrier load the copper single atoms; the carrier carbon nanotubes have a unique tubular structure and an extremely high specific surface area, which can promote the copper active centers to be stably dispersed as single atoms on the carrier surface, the active centers in the catalyst are at the atomic level, the effective utilization rate of the copper active centers is improved, and the waste of the underlying atoms is reduced, so that more copper active centers participate in the reaction of catalytic synthesis of chiral binaphthol (BINOLs) molecules, and the efficiency of the catalytic reaction is accelerated. At the same time, the strong chemical bonds and unique lattice structure of the carbon nanotubes enable them to remain stable under high temperature, high pressure and other conditions, which is conducive to the separation and reuse of the catalyst, thereby improving the effect of the catalyst in catalytic synthesis of chiral binaphthol (BINOLs) molecules and overcoming the current defect of low effect of copper catalyst in catalytic synthesis of chiral binaphthol molecules.

[0030] At the same time, carbon nanotubes are composed of pure carbon elements and do not contain additional salt or impurity elements, which avoids the influence of salt or impurity elements on the catalytic synthesis of chiral binaphthol molecules. At the same time, when different batches of carbon nanotubes are used, the impact is also less, which is conducive to the long-term stability of the catalytic synthesis of chiral binaphthol (BINOLs) molecules.

[0031] The copper atomic-level dispersed catalyst provided in the present application will be specifically described below in conjunction with embodiments and experimental examples.

[0032] Example 1

[0033] Example 1 of the present application provides a method for preparing a copper atomic-level dispersed catalyst, the preparation method comprising the steps of preparing a Cu-EDTA solution, loading a complex copper, and loading copper atoms.

[0034] Wherein, the steps of preparing the Cu-EDTA solution include:

[0035] Mix 0.00629 mmol of disodium ethylenediaminetetraacetate (EDTA-2Na), 0.00629 mmol of copper nitrate hexahydrate (Cu(NO3)2·6H2O) and 40 ml of deionized water, add NaOH to adjust the pH to 6-7, and obtain 40 mL, 10 mg / ml Cu-EDTA complex solution (Cu:EDTA=1:1).

[0036] The steps of loading the complexed copper include:

[0037] Add 250µl of 10mg / ml Cu-EDTA complex solution (Cu:EDTA=1:1), 500mg of carbon nanotubes and 20mL of deionized water into a 50ml beaker, stir magnetically at room temperature for 1h, then heat to 100°C, remove the solvent water under magnetic stirring, and after the solvent is evaporated, move the catalyst to a blower dryer and dry at 70°C for 5h to obtain a copper atomic-level dispersed catalyst precursor loaded with complexed copper.

[0038] The steps of loading copper atoms include:

[0039] The copper atomic-level dispersed catalyst precursor loaded with complex copper was moved to a tubular furnace for calcination. The calcination conditions were as follows: in a nitrogen atmosphere, the temperature was increased from 20°C to 700°C at a heating rate of 5°C / min, and the temperature was kept at 700°C for 2 hours before being cooled to room temperature. During the calcination process, the complex copper ligand skeleton was thermally decomposed to obtain a copper atomic-level dispersed catalyst with carbon nanotubes as the carrier. The mass of the copper atomic-level dispersed catalyst was about 478 mg, and the copper doping amount was about 0.5wt%, which can be recorded as 0.5wt%Cu-N / C.

[0040] Experimental Example 1

[0041] Experimental Example 1 of the present application conducts structural and performance tests on the copper atomic-level dispersed catalyst provided in Example 1.

[0042] Electron microscopy images of copper atomic-level dispersed catalysts Figure 1 As shown, from Figure 1 It can be clearly seen that nano-sized particles are stably dispersed on the surface of carbon nanotubes. Figure 2 It can be seen from the X-ray diffraction pattern that the particles with a size of about nanometers should be single copper atoms, which means that in the preparation method provided in the present application, copper can be dispersed on the surface of carbon nanotubes at the atomic level.

[0043] Among them, the performance test of copper atomic-level dispersed catalyst, using β-naphthol as the reaction substrate, asymmetric catalytic synthesis of chiral binaphthol, the structural diagram of chiral binaphthol is shown in Figure 3 The synthetic route is shown in the attached Figure 4 shown.

[0044] The process of synthesizing chiral binaphthol by asymmetric reaction of β-naphthol catalyzed by copper atomically dispersed catalyst includes:

[0045] 800 mg of copper atomic-level dispersed catalyst was weighed into a 40 mL high-pressure reactor, 20 mmol of β-naphthol substrate was added and mixed in 20 mL of methanol, the reactor was sealed, O2 was filled into the reactor six times and discharged, all the air in the reactor was discharged, and then oxygen was introduced to make the pressure reach 0.5 MPa, and it was placed at 70 ° C and stirred at a stirring rate of 500 r / min. The reaction time was 24 h, and the product chiral dinaphthol was obtained with a yield of 89.41% and a conversion number of 57.31. Its hydrogen spectrum and carbon spectrum are as follows: Figure 5-6 shown.

[0046] from Figure 4-6 It can be seen that the atomically dispersed copper catalyst provided in the present application catalyzes β-naphthol, and uses atomically dispersed copper as the active center, which can efficiently catalyze the asymmetric reaction of β-naphthol to synthesize chiral binaphthol, and the yield of the product is relatively high, which shows that the atomically dispersed copper can improve the effect of the catalyst in catalyzing the synthesis of chiral binaphthol (BINOLs) molecules through effective utilization; at the same time, the atomically dispersed copper is dispersed on the carbon nanotubes, which is conducive to the recycling of the atomically dispersed copper.

[0047] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some or all of the technical features thereof may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. Application of a copper atomic-level dispersed catalyst in catalytic synthesis of chiral binaphthol, characterized in that: The application specifically includes: using a copper atomic-level dispersed catalyst to catalyze an asymmetric reaction of β-naphthol to synthesize chiral binaphthol; in the asymmetric reaction, the reaction atmosphere is oxygen, the reaction pressure is 0.2-0.8 MPa, the reaction temperature is 50-90° C., and the reaction time is 16-32 hours; The method for preparing the copper atomic-level dispersed catalyst comprises the following steps: Step S1, adding carbon nanotubes into a Cu-EDTA solution and stirring until the solvent is completely evaporated, and drying to obtain a copper atomic-level dispersed catalyst precursor; Step S2, calcining the copper atomic-level dispersed catalyst precursor at high temperature to obtain the copper atomic-level dispersed catalyst.

2. The use of a copper atomic-level dispersed catalyst according to claim 1 in catalytic synthesis of chiral binaphthol, characterized in that: In the asymmetric reaction, the ratio of the copper atomic-level dispersed catalyst to the β-naphthol is 800 mg: 10-50 mmol.

3. The use of a copper atomic-level dispersed catalyst according to claim 1 in catalytic synthesis of chiral binaphthol, characterized in that: In step S1, the amount of the carbon nanotubes is 500 mg, the concentration of the Cu-EDTA solution is 5 to 15 mg / mL, and the amount is 100 to 300 μL.

4. The use of a copper atomic-level dispersed catalyst according to claim 1 in catalytic synthesis of chiral binaphthol, characterized in that: In step S1, the temperature during the stirring process is 80-120°C.

5. The use of a copper atomic-level dispersed catalyst according to claim 1 in catalytic synthesis of chiral binaphthol, characterized in that: In step S2, the atmosphere of the high-temperature calcination is nitrogen, the heating rate is 5°C / min, the holding time is 600-800°C, and the time is 2-4h.

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