Reducing support-loaded metal nanoparticles and their use in the preparation of azoarenes

Abstract

The application relates to a reducing carrier loaded metal nanoparticle and its application in preparation of azoarenes, relates to the field of catalytic hydrogenation of nitroarenes, and is characterized in that the reducing carrier loaded metal nanoparticle is dispersed into an alcohol solvent containing a bidentate amine assistant, a nitroarene is added, air in a reaction container is discharged by introducing hydrogen, hydrogen with a pressure of 0.1-0.6 MPa is kept, a catalytic hydrogenation reaction is carried out below 5 DEG C, after the hydrogenation reaction is completed, air is introduced into the reaction container to carry out an oxidation reaction, and azobenzene (I) is obtained, wherein R is selected from hydrogen, an alkyl group, halogen, an alkoxy group, a hydroxyl group, an amino group or an acyl group.

Description

Technical Field

[0001] This invention relates to the field of catalytic hydrogenation of nitroaromatics, and more specifically to a reducing support-supported metal nanoparticle and its application in the preparation of azoaromatics. Background Technology

[0002] Catalysis is a key discipline for sustainable development, enabling chemical transformations to occur at lower temperatures while reducing or even eliminating the formation of byproducts. Therefore, the preparation of more active, and especially more selective, catalysts is crucial. Selectivity is essential for chemical transformations, particularly when a reaction involves multiple reactive groups and only one specific group needs to be transformed while others are avoided. These reactions include direct, condensation, and disproportionation pathways, each containing numerous products. Furthermore, the presence of one or more substituents on the aromatic ring, such as C=C, C≡C, C=O, C=N, C≡N, and CX (halogens), presents a significant challenge in selectively recognizing and transforming nitro groups to obtain functionalized nitrosamines, hydroxylamines, and amines. Simultaneously, the design and synthesis of novel catalysts with high catalytic selectivity holds immense application value.

[0003] Azobenzene oxide, diphenylhydrazine, and azobenzene are essential intermediates for the production of many fine and bulk chemicals, such as dyes, pharmaceuticals, and agrochemicals. According to literature reports (ChemCatChem, 2009, 1, 210-221; Chem.Rev., 2019, 119, 2611-2680), while current catalysts can effectively achieve the deep hydrogenation of nitroaromatics to the corresponding amines, the high selectivity for azobenzene oxide, diphenylhydrazine, and azobenzene remains a long-standing scientific and technological challenge. It is well known that heterogeneous noble metal catalysts can continuously activate H2 at low temperatures and achieve rapid hydrogenation of unsaturated groups, typically exhibiting high activity. However, these catalysts lack target group recognition, resulting in very low selectivity. On the other hand, stoichiometric reducing agents, such as Na₂S₂O₄, Fe, Sn, or Zn, can selectively hydrogenate numerous unsaturated compounds, are low-cost, and easy to operate. However, their fatal flaw lies in the large amount of solid waste generated during the reaction, which is environmentally unfriendly and unsustainable (Science, 2006, 313, 332-334). If their disadvantages can be avoided and their advantages integrated, that would undoubtedly be the best choice. Summary of the Invention

[0004] On the one hand, a catalyst for selectively catalytically hydrogenating nitrobenzene is provided; on the other hand, a method for selectively preparing azobenzene oxide, diphenylhydrazine, and azobenzene from nitrobenzene is provided.

[0005] The technical solution of the present invention is as follows:

[0006] In a first aspect, a metal nanoparticle catalyst supported on a reducible support is provided, wherein the metal includes one or more of Pt, Pd, Ni, Ir, Ru, and Rh, the metal nanoparticles have a particle size of less than 5 nm, and the reducible support includes one or more of SnO2, Fe2O3, Fe3O4, FeO, Co3O4, TiO2, MnO2, CuO, ZnO, Ga2O3, In2O3, or GeO2; based on the total mass of the catalyst, the content of metal nanoparticles in the catalyst is approximately 0.5-10 wt%, and the content of the reducible support is approximately 90-99.5 wt%.

[0007] In some embodiments, the content of metal nanoparticles in the catalyst is about 0.5-5.0 wt%.

[0008] Secondly, a method for selectively preparing azobenzene from nitrobenzene is provided. The method involves dispersing metal nanoparticles supported on a reducing support as described in the first aspect of the invention into an organic solvent containing a bidentate amine auxiliary agent, adding nitroaromatic hydrocarbons, purging hydrogen gas to purge air from the reaction vessel, maintaining a hydrogen pressure of 0.1-0.6 MPa, and carrying out a catalytic hydrogenation reaction below 5°C. After the hydrogenation reaction is completed, air is introduced into the reaction vessel to carry out an oxidation reaction to obtain azobenzene (I).

[0009] R is selected from hydrogen, alkyl, halogen, alkoxy, hydroxy, amino, or acyl.

[0010] Thirdly, a method for preparing diphenylhydrazine is provided, wherein metal nanoparticles supported on a reducing support are dispersed in an organic solvent containing a bidentate amine auxiliary agent, nitroaromatic hydrocarbons are added, hydrogen gas is introduced to purge air from the reaction vessel, and a hydrogen gas pressure of 0.1-0.6 MPa is maintained. A catalytic hydrogenation reaction is carried out below 5°C. After the hydrogenation reaction is completed, air is introduced into the reaction vessel to carry out an oxidation reaction to obtain azobenzene(I), and then hydrogen gas at 0.1-0.6 MPa is introduced to carry out a catalytic hydrogenation reaction. After the hydrogenation reaction is completed, diphenylhydrazine(II) is obtained.

[0011] Each of the R groups is independently selected from hydrogen, alkyl, halogen, alkoxy, hydroxy, amino, or acyl groups.

[0012] Fourthly, a method for preparing azobenzene is provided. Metal nanoparticles supported on a reducing support are dispersed in an organic solvent containing a bidentate amine auxiliary agent. Nitroaromatic hydrocarbons are added, and hydrogen gas is introduced to purge air from the reaction vessel, maintaining a hydrogen pressure of 0.1-0.6 MPa. A catalytic hydrogenation reaction is carried out below 5°C. After the hydrogenation reaction is complete, air is introduced into the reaction vessel to carry out an oxidation reaction to obtain azobenzene oxide (I). Then, hydrogen gas at 0.1-0.6 MPa is introduced to carry out a catalytic hydrogenation reaction. After the hydrogenation reaction is complete, diphenylhydrazine (II) is obtained. Air is then introduced into the reaction vessel to oxidize diphenylhydrazine to obtain azobenzene (III).

[0013] Each of the R groups is independently selected from hydrogen, alkyl, halogen, alkoxy, hydroxy, amino, or acyl groups.

[0014] In some embodiments, the bidentate amine adjuvant is selected from one or more of ethylenediamine, propylenediamine, butanediamine, pentanediamine, and / or hexamethylenediamine.

[0015] In some embodiments, the bidentate amine accounts for 40%-100% of the total volume of the organic solvent.

[0016] In some embodiments, the organic solvent is selected from one or more of ethanol, methanol, cyclohexanol, isopropanol, cyclohexane, tetrahydrofuran, dioxane, dimethyl sulfoxide, and / or chloroform.

[0017] The above-mentioned technical solution has the following beneficial effects:

[0018] In this invention, metal nanoparticles supported on a reducible carrier are used as catalysts, and bidentate amine is introduced as an auxiliary agent. Azobenzene oxide, diphenylhydrazine, and azobenzene can be prepared by selectively reducing or oxidizing the reaction system with hydrogen or air. The three preparation methods of this invention have mild reaction conditions, high conversion rate of nitroaromatic hydrocarbons and selectivity of target products, and good cycle stability.

[0019] Terminology Explanation

[0020] In this invention, "room temperature" and "normal temperature" refer to ambient temperature, ranging from approximately 10°C to approximately 40°C. In some embodiments, "room temperature" or "normal temperature" refers to a temperature ranging from approximately 20°C to approximately 30°C; in other embodiments, "room temperature" or "normal temperature" refers to a temperature ranging from approximately 25°C to approximately 30°C; and in still other embodiments, "room temperature" or "normal temperature" refers to 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, etc.

[0021] The term "anaerobic" in this invention 1 "H-NMR technology" refers to the process of sampling, preparing, and performing hydrogenation of nitroaromatic hydrocarbons under anaerobic conditions.1 H-NMR test.

[0022] In this invention, the term "bis-dental amine" refers to one of ethylenediamine, propylenediamine, butanediamine, pentanediamine, and hexamethylenediamine.

[0023] In this invention, the term "chelation" refers to the coordination interaction between a bidentate or polydentate ligand and the coordination center atom.

[0024] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0025] The terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, or article that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, or article. Unless otherwise specified, an element defined by the phrase "comprising..." or "including..." does not exclude the presence of other elements in the process, method, or article that includes said element. Furthermore, in this document, "greater than," "less than," "exceeding," etc., are understood to exclude the stated number; "above," "below," "within," etc., are understood to include the stated number.

[0026] All numerical values ​​disclosed in this invention are approximate, regardless of whether the terms "about" or "approximately" are used in connection with them. They may differ by 1%, 2%, 5%, or sometimes even 10% to 20%. Whenever a numerical range with a lower limit RL and an upper limit RU is disclosed, it is considered that any numerical value falling within said range is specifically disclosed. Specifically, the following numerical values ​​within said range are specifically disclosed: R = RL + k * (RU - RL), where k is a variable ranging from 1% to 100% in increments of 1%, i.e., k is 1%, 2%, 3%, 4%, 5%, ..., 50%, 51%, 52%, ..., 95%, 96%, 97%, 98%, 99%, or 100%. Furthermore, any numerical range defined by the two R numbers defined above is also specifically disclosed.

[0027] Certain embodiments of the invention will now be described in detail, examples of which are illustrated by the accompanying structural and chemical formulas. The invention is intended to encompass all alternatives, modifications, and equivalents, all of which are included within its scope. Those skilled in the art will recognize that many similar or equivalent methods and materials can be used to practice the invention. The invention is by no means limited to the methods and materials described herein. In the event that one or more of the incorporated documents, patents, and similar materials differ from or contradict this application (including, but not limited to, defined terminology, application of terminology, described techniques, etc.), this application shall prevail. Attached Figure Description

[0028] Figure 1 This is a transmission electron microscope image of the Pt NPs / SnO2 catalyst with a metal loading of 1 wt% prepared in Example 1.

[0029] Figure 2 This is the powder X-ray diffraction pattern of the Pt NPs / SnO2 catalyst with a metal loading of 1 wt% prepared in Example 1.

[0030] Figure 3 This is a scanning transmission electron microscope image of the Pt NPs / SnO2 catalyst with a metal loading of 1 wt% prepared in Example 1.

[0031] Figure 4 The energy dispersive spectroscopy characterization of the Pt NPs / SnO2 catalyst with a metal loading of 1 wt% prepared in Example 1 is shown.

[0032] Figure 5 These are high-resolution transmission electron microscope images and corresponding fast Fourier transform analysis images of the Pt NPs / SnO2 catalyst with a metal loading of 1 wt% prepared in Example 1.

[0033] Figure 6 This refers to the reaction before and after the oxidation of hydroxyaniline to azobenzene in Example 7. 1 1H NMR spectrum.

[0034] Figure 7 This is the high-performance liquid chromatogram of azobenzene prepared in Example 7.

[0035] Figure 8 This is the 1H NMR spectrum before and after the hydrogenation of azobenzene to diphenylhydrazine in Example 8.

[0036] Figure 9 This is the high-performance liquid chromatogram of diphenylhydrazine prepared in Example 8.

[0037] Figure 10 In Example 1, the hydrogenation of azobenzene produced aniline as the main product, not diphenylhydrazine.1 1H NMR spectrum.

[0038] Figure 11 This refers to the reaction before and after the oxidation of diphenylhydrazine to azobenzene in Example 9. 1 1H NMR spectrum. Detailed Implementation

[0039] To enable those skilled in the art to better understand the technical solutions of the present invention, some non-limiting embodiments are further disclosed below to provide a more detailed description of the present invention.

[0040] Example 1: Preparation of metal nanoparticle catalysts supported on reducing supports

[0041] Weigh 1 g of SnO2 support and place it in a 250 mL round-bottom flask. Add 150 mL of ultrapure water and sonicate for 1 min. Stir thoroughly for 2 h using a stirrer. Slowly add 5 mL of potassium chloroplatinate (K2PtCl4) aqueous solution (5 mg / mL) and 4 mL of sodium borohydride (NaBH4) aqueous solution (1 mg / mL). Continue stirring for 2 h. Collect the solid by centrifugation or filtration, wash three times with ultrapure water, and dry in a forced-air drying oven at 60 °C for 24 h to obtain a Pt NPs / SnO2 catalyst with a Pt loading of 1 wt%. In other embodiments, the Pt loading can be 0.5-10 wt%, preferably 0.5-5 wt%.

[0042] The Pt NPs / SnO2 catalyst prepared in this example was analyzed:

[0043] Figure 1 These are transmission electron microscope images of the catalyst, showing that only small-sized Pt NPs are dispersed on the surface of the SnO2 support, while no large-sized particles are present, with particle sizes less than 5 nm.

[0044] Figure 2 These are the powder X-ray diffraction (PXRD) patterns of the catalysts, where Pt NPs / SnO2 is the PXRD pattern of the catalyst and SnO2 is the PXRD pattern of the standard. Analysis was performed by referring to the PDF#41-1445 SnO2 and PDF#07-0802 Pt X-ray diffraction crystal phase data cards, respectively. Figure 2 Only diffraction peaks of SnO2 can be observed. SnO2 has a rutile structure, belongs to the tetragonal crystal system, and has the space group P42 / mnm. The absence of diffraction peaks corresponding to face-centered cubic Pt NPs further proves that the nanoparticles are all small in size, with no large particles present.

[0045] Figure 3The image is a scanning transmission electron microscope image of the catalyst. The results also show that the SnO2 support surface has only small-sized Pt NPs, no large-sized particles, and the particle size is less than 5 nm.

[0046] Figure 4 The energy dispersive spectroscopy characterization of the catalyst showed that small-sized Pt NPs were uniformly loaded on the surface of the SnO2 support.

[0047] Figure 5 The high-resolution transmission electron microscope images and corresponding fast Fourier transform (FFT) analyses of the catalyst show that the (111) interplanar spacing of Pt NPs is... It has a face-centered cubic lattice structure and a space group of Fm-3m. In summary, the structure of the PtNPs / SnO2 catalyst is that uniformly small Pt NPs are uniformly supported on the surface of the SnO2 support.

[0048] Examples 2-6: Preparation of azobenzene using Pt NPs / SnO2 catalysts with different loadings

[0049] 19.5 mg of Pt NPs / SnO2 catalysts with different metal loadings (0.5 wt%, 2 wt%, 3 wt%, 4 wt%, and 5 wt%) were uniformly dispersed in 4.9 mL of ethanol containing 0.1 mL of ethylenediamine. The catalysts were then added to a 48 mL thick-walled, pressure-resistant glass flask. The flask was cooled and kept at 0°C. 102 μL of nitrobenzene was added, and hydrogen gas at 0.1 MPa was introduced to purge the air from the flask for 1 min. The pressure-resistant flask was then sealed, maintaining a hydrogen gas pressure of 0.1 MPa. The reaction was carried out with thorough stirring. After 120 min, 60 min, 40 min, 30 min, and 20 min of reaction time, air was introduced into the reaction system, and stirring was continued for 10 min to obtain azobenzene.

[0050]

[0051] Example 7: Selective catalytic hydrogenation of nitroaromatics to prepare azobenzene

[0052] 19.5 mg of a 1 wt% Pt NPs / SnO2 catalyst was uniformly dispersed in 6.5 mL of dioxane containing 0.1 mL of hexamethylenediamine. This mixture was then added to a 48 mL thick-walled, pressure-resistant glass flask. The flask was cooled and kept at 0°C. 102 μL of nitrobenzene was added, and hydrogen gas at 0.1 MPa was introduced to purge the air from the flask for 1 min. The pressure-resistant flask was then sealed, maintaining a hydrogen pressure of 0.1 MPa. The reaction was carried out with thorough stirring. After 75 min of reaction, air was introduced into the reaction system, and stirring was continued at room temperature for 10 min. Under anaerobic conditions, the reaction proceeded through… 1H NMR was used to detect the conversion rate and selectivity of the reaction process.

[0053] like Figure 6 As shown, at a reaction time of 0 min, only nitrobenzene was detected. After the hydrogenation reaction proceeded for 75 min, only hydroxyaniline was detected in the system, indicating that nitrobenzene was completely converted and selectively converted to hydroxyaniline. After the subsequent oxidation reaction proceeded for 10 min, only azobenzene was detected in the system, indicating that hydroxyaniline was completely converted to azobenzene. The high-performance liquid chromatography (HPLC) results also confirmed this result. Figure 7 ).

[0054] Example 8: Selective catalytic hydrogenation of nitroaromatics to prepare diphenylhydrazine

[0055] 3.90 mg of a 5.0 wt% Pt NPs / SnO2 catalyst was uniformly dispersed in 4.9 mL of ethanol containing 0.1 mL of ethylenediamine. This mixture was then added to a 48 mL thick-walled, pressure-resistant glass flask. The flask was cooled and kept at 0°C. 102 μL of nitrobenzene was added, and hydrogen gas at 0.1 MPa was introduced to purge the air from the flask for 1 min. The flask was then sealed, maintaining a hydrogen pressure of 0.1 MPa, and the reaction was carried out with thorough stirring. After 75 min of reaction, air was introduced into the reaction system, and stirring was continued for 10 min. Hydrogen gas at 0.1 MPa was then introduced to purge the air from the flask for 1 min. The reaction temperature was set to 60°C, and the flask was sealed, maintaining a hydrogen pressure of 0.1 MPa. The reaction was carried out with thorough stirring for 20 min. Under anaerobic conditions, the reaction proceeded... 1 1H NMR was used to detect the conversion rate and selectivity of the reaction process. For example, Figure 8 As shown, at a reaction time of 0 min, only nitrobenzene was present. After the first hydrogenation reaction proceeded for 75 min, only hydroxyaniline was present in the system, indicating that nitrobenzene was completely converted and selectively converted to hydroxyaniline. After the subsequent oxidation reaction proceeded for 10 min, only azobenzene was present in the system, indicating that hydroxyaniline was completely converted to azobenzene. After the second hydrogenation reaction proceeded for 20 min, only diphenylhydrazine was present in the system, indicating that azobenzene was completely converted to diphenylhydrazine. The high-performance liquid chromatography (HPLC) results also confirmed this result. Figure 9 ).

[0056] Example 9: Method for preparing azobenzene

[0057] 19.5 mg of a 3.90 wt% Pt NPs / SnO2 catalyst was uniformly dispersed in 4.9 mL of ethanol containing 0.1 mL of ethylenediamine. This mixture was then added to a 48 mL thick-walled, pressure-resistant glass flask. The flask was cooled and kept at 0°C. 102 μL of nitrobenzene was added, and hydrogen gas at 0.1 MPa was introduced to purge the flask for 1 min to remove air. The flask was then sealed, maintaining a hydrogen pressure of 0.1 MPa, and the reaction was carried out with thorough stirring. After 75 min of reaction, air was introduced into the reaction system, and stirring was continued for 10 min. Hydrogen gas at 0.1 MPa was introduced again to purge the flask for 1 min to remove air. The reaction temperature was set to 60°C. The flask was sealed, maintaining a hydrogen pressure of 0.1 MPa, and the reaction was carried out with stirring until diphenylhydrazine was obtained. Air was then introduced into the reaction vessel for oxidation to obtain azobenzene. Under anaerobic conditions, the reaction proceeded through… 1 H NMR is used to detect the conversion rate and selectivity of the reaction process, such as Figure 11 As shown.

[0058] Examples 10-39

[0059] While keeping other reaction conditions unchanged in Example 7, the type of substrate was changed by controlling a single variable. Examples 10-36 used p-methylnitrobenzene, m-methylnitrobenzene, o-methylnitrobenzene, p-chloronitrobenzene, m-chloronitrobenzene, o-chloronitrobenzene, p-fluoronitrobenzene, m-fluoronitrobenzene, o-fluoronitrobenzene, p-bromonitrobenzene, p-iodonitrobenzene, p-ethylnitrobenzene, p-propylnitrobenzene, p-tert-butylnitrobenzene, p-nitrobenzaldehyde, p-nitrobenzeneacetophenone, p-nitrobenzenonitrile, p-nitrostyrene, p-nitrobenzeneethyne, p-nitrobenzamide, p-nitrobenzamide chloride, p-nitrobenzamide, p-nitrobenzeneacetyl chloride, p-nitrobenzamide, p-nitrobenzeneacetylene ... Nitro groups can be completely converted within 80 minutes, the selectivity of azobenzene is greater than 98%, and other substituents can be retained.

[0060] Examples 40-45

[0061] While keeping other reaction conditions unchanged in Example 7, the metal loading was varied to 0.5 wt%, 2 wt%, 4 wt%, 6 wt%, 8 wt%, and 10 wt%. Nitrobenzene was completely converted within 100 min, and the product was azobenzene.

[0062] Examples 46-56

[0063] Keeping all other conditions unchanged from Example 7, only the catalyst was changed to one of Pt / Fe2O3, Pt / Fe3O4, Pt / FeO, Pt / Co3O4, Pt / TiO2, Pt / MnO2, Pt / CuO, Pt / ZnO, Pt / Ga2O3, Pt / In2O3, Pt / GeO2, Pt / Al2O3, Pt / SiO2, and Pt / MgO. The reaction was carried out for 85 min (hydrogenation time was 75 min, oxidation time was 10 min). The conversion rate of nitrobenzene was close to 100%, and the selectivity of azobenzene oxide was about 100%. The conversion rate and selectivity are shown in the table below.

[0064]

[0065] Comparative Example 1

[0066] Keeping the reaction conditions unchanged from Example 7, after obtaining azobenzene, Pt / SnO2 was used as a catalyst in an ethanol solvent. Hydrogen gas at 0.1 MPa was introduced and purged for 1 minute to remove air from the flask. The reaction temperature was set to 60 degrees Celsius, and the pressure-resistant flask was sealed, maintaining 0.1 MPa of hydrogen gas. The reaction was carried out with thorough stirring. Under anaerobic conditions, through… 1 1H NMR was used to detect the conversion rate and selectivity of the reaction process. For example, Figure 10 As shown, after 25 minutes of hydrogenation, aniline is produced as a byproduct, and diphenylhydrazine cannot be obtained with high selectivity.

[0067] Comparative Example 2

[0068] 19.5 mg of a 1 wt% Pt NPs / SnO2 catalyst was uniformly dispersed in 4.9 mL of ethanol containing 0.1 mL of n-butylamine. This mixture was then added to a 48 mL thick-walled, pressure-resistant glass flask. The flask was cooled and kept at 0°C. 102 μL of nitrobenzene was added, and hydrogen gas at 0.1 MPa was introduced to purge the air from the flask for 1 min. The pressure-resistant flask was then sealed, maintaining a hydrogen pressure of 0.1 MPa. The reaction was carried out with thorough stirring. After 75 min of reaction, air was introduced into the reaction system, and stirring was continued at room temperature for another 10 min. After the reaction was complete, the mixture was... 1 The conversion and selectivity of the reaction process were detected by H NMR, and a mixture containing azobenzene oxide was obtained, wherein the aniline content was greater than 70% and the yield of azobenzene oxide was less than 30%.

[0069] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. The use of a reducing-supported metal nanoparticle catalyst in the preparation of azobenzene oxide, diphenylhydrazine, or azobenzene, characterized in that, The metal includes one or more of Pt, Pd, Ni, Ir, Ru, and Rh, the metal nanoparticles have a particle size of less than 5 nm, and the reducing support includes one or more of SnO2, Fe2O3, Fe3O4, FeO, Co3O4, TiO2, MnO2, CuO, ZnO, Ga2O3, In2O3, or GeO2; based on the total mass of the catalyst, the content of metal nanoparticles in the catalyst is 0.5-10 wt%, and the content of reducing support is 90-99.5 wt%.

2. The use as described in claim 1, characterized in that, The catalyst contains 0.5-5.0 wt% metal nanoparticles.

3. A method for selectively preparing azobenzene from nitroaromatic hydrocarbons, characterized in that, include: The metal nanoparticles supported on the reducing carrier as described in claim 1 or 2 are dispersed in an organic solvent containing a bidentate amine auxiliary agent. Nitroaromatic hydrocarbons are added, and hydrogen gas is introduced to purge the air from the reaction vessel, maintaining a hydrogen pressure of 0.1-0.6 MPa. A catalytic hydrogenation reaction is carried out at a temperature below 5°C. After the hydrogenation reaction is completed, air is introduced into the reaction vessel to carry out an oxidation reaction to obtain azobenzene(I). (I), Each of the R groups is independently selected from hydrogen, alkyl, halogen, alkoxy, hydroxy, amino, or acyl groups.

4. The method as described in claim 3, characterized in that, The bidentate amine adjuvant is selected from one or more of ethylenediamine, propylenediamine, butanediamine, pentanediamine, and hexamethylenediamine.

5. The method as described in claim 3, characterized in that, The bidentate amine auxiliary agent accounts for 40%-100% of the total volume of the organic solvent.

6. The method as described in claim 3, characterized in that, The organic solvent is selected from one or more of ethanol, methanol, cyclohexanol, isopropanol, cyclohexane, tetrahydrofuran, dioxane, dimethyl sulfoxide, and chloroform.

7. A method for preparing diphenylhydrazine, characterized in that, include: The metal nanoparticles supported on the reducing carrier as described in claim 1 or 2 are dispersed in an organic solvent containing a bidentate amine auxiliary agent, nitroaromatic hydrocarbons are added, hydrogen gas is introduced to purge the air from the reaction vessel, and the hydrogen gas is maintained at 0.1-0.6 MPa. A catalytic hydrogenation reaction is carried out at a temperature below 5°C. After the hydrogenation reaction is completed, air is introduced into the reaction vessel to carry out an oxidation reaction to obtain azobenzene (I). Then, hydrogen gas at 0.1-0.6 MPa is introduced to carry out a catalytic hydrogenation reaction. After the hydrogenation reaction is completed, diphenylhydrazine (II) is obtained. (II), Each of the R groups is independently selected from hydrogen, alkyl, halogen, alkoxy, hydroxy, amino, or acyl groups.

8. The method as described in claim 7, characterized in that, The bidentate amine adjuvant is selected from one or more of ethylenediamine, propylenediamine, butanediamine, pentanediamine, and hexamethylenediamine.

9. The method as described in claim 7, characterized in that, The bidentate amine auxiliary agent accounts for 40%-100% of the total volume of the organic solvent.

10. The method as described in claim 7, characterized in that, The organic solvent is selected from one or more of ethanol, methanol, cyclohexanol, isopropanol, cyclohexane, tetrahydrofuran, dioxane, dimethyl sulfoxide, and chloroform.

11. A method for preparing azobenzene, characterized in that, include: The metal nanoparticles supported on the reducing carrier as described in claim 1 or 2 are dispersed in an organic solvent containing a bidentate amine auxiliary agent. Nitroaromatic hydrocarbons are added, and hydrogen gas is introduced to purge air from the reaction vessel, maintaining a hydrogen pressure of 0.1-0.6 MPa. A catalytic hydrogenation reaction is carried out below 5°C. After the hydrogenation reaction is complete, air is introduced into the reaction vessel to carry out an oxidation reaction to obtain azobenzene(I). Then, hydrogen gas at 0.1-0.6 MPa is introduced to carry out a catalytic hydrogenation reaction, and diphenylhydrazine(II) is obtained after the hydrogenation reaction is complete. Then, air is introduced into the reaction vessel to oxidize diphenylhydrazine(II) to obtain azobenzene(III). (III), Each of the R groups is independently selected from hydrogen, alkyl, halogen, alkoxy, hydroxy, amino, or acyl groups.

12. The method as described in claim 11, characterized in that, The bidentate amine adjuvant is selected from one or more of ethylenediamine, propylenediamine, butanediamine, pentanediamine, and hexamethylenediamine.

13. The method as described in claim 11, characterized in that, The bidentate amine auxiliary agent accounts for 40%-100% of the total volume of the organic solvent.

14. The method as described in claim 11, characterized in that, The organic solvent is selected from one or more of ethanol, methanol, cyclohexanol, isopropanol, cyclohexane, tetrahydrofuran, dioxane, dimethyl sulfoxide, and chloroform.

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