A catalyst having a phthalocyanine-like metal atom structure, and a preparation method and application thereof

Abstract

The application discloses a catalyst with a phthalocyanine-like metal atom structure, and a preparation method thereof, which comprises the following steps: mixing metal powder with an acidic aqueous solution and performing ultrasonic reaction, then adding a precursor solution containing graphene oxide, a peroxide and a nitrogen source, performing hydrothermal reaction to obtain black hydrogel, and washing; stirring the black hydrogel in dilute acid, and washing to obtain the monatomic catalyst. The application in-situ constructs a phthalocyanine-like metal atom structure on an active substrate graphene oxide, improves the electron transmission capacity, has excellent catalytic activity and stability, and has a wide application prospect in the fields of energy conversion, environmental protection, fine chemical industry and the like; and the preparation method is simple, can significantly reduce the preparation cost of the phthalocyanine structure catalyst, and provides a new idea for the preparation of high-performance catalysts.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of catalysts, and particularly relates to a catalyst with a phthalocyanine-like-metal atom structure and a preparation method and application thereof. BACKGROUND

[0002] Single-atom catalysts have attracted much attention due to their excellent catalytic effect and high atom utilization. Research on single-atom catalysts helps to improve catalyst performance and atom utilization, which is particularly important in the fields of energy conversion and environmental governance. However, single-atom catalysts are usually not stable enough in thermodynamics due to incomplete surface coordination, which makes them more prone to shedding or agglomeration, thereby affecting the atom utilization and stability of the catalyst. To solve this problem, adjusting the coordination environment around the metal single atom has become a research hotspot in the field of single-atom catalysts.

[0003] At present, a large number of studies have successfully achieved single-atom anchoring by utilizing the structural characteristics of specific compounds themselves. The prepared single-atom catalysts have advantages such as high selectivity, high activity, and high stability, such as: synthesizing catalysts with stable phthalocyanine structure by using metal phthalocyanine molecules (Rational design of heterogenized molecular phthalocyanine hybrid single-atom electrocatalyst towards two-electron oxygen reduction, Nature Communication, 2023, 14, 1426); synthesizing catalysts with curved active sites by using nanodiamonds (Meso / microporous single-atom catalysts with curved Fe-N4 sites boost the oxygen reduction reaction activity, Angewandte Chemie International Edition, e202415691). However, the anchoring of these single atoms is achieved by using specific precursors or endogenous structures, and the construction of the coordination environment of metal single atoms is limited by the special molecular structure of the precursor itself or the special morphology of the carrier, making the preparation strategy of such single-atom catalysts have great challenges, such as: (1) the preparation method does not have good universality; (2) the coordination environment of the single-atom site cannot be accurately regulated; (3) the introduced characteristic structure is easy to be destroyed in the reaction.

[0004] Therefore, it is of great significance to further study a scheme capable of constructing a stable coordination structure in situ on an active base material, reasonably regulating a coordination environment around a single atom, reducing production cost of a single atom catalyst, and improving stability of the catalyst. SUMMARY

[0005] The main purpose of the present application is to solve the problems and deficiencies of the prior art, and provide a catalyst with a phthalocyanine-like metal atom structure, which in-situ constructs a phthalocyanine-like metal atom (including iron, cobalt, nickel, etc.) structure on an active base graphene oxide, can balance excellent catalytic activity and stability, and simplifies the preparation process.

[0006] To achieve the above purpose, the technical scheme adopted by the present application is:

[0007] A catalyst with a phthalocyanine-like metal atom structure, the preparation method thereof comprises the following steps:

[0008] Mixing the metal powder with the acidic aqueous solution and performing ultrasonic reaction, adding the precursor solution containing graphene oxide, peroxide and nitrogen source into the solution after the metal reaction is completed, performing hydrothermal reaction to obtain black hydrogel, and washing; putting the black hydrogel into dilute acid for stirring treatment, and washing to obtain the catalyst with a phthalocyanine-like metal atom structure.

[0009] In the above scheme, the metal powder is selected from one or more of iron powder, cobalt powder, nickel powder, etc., and the average particle size of the metal powder is 1-10 μm.

[0010] In the above scheme, the acidic aqueous solution is a hydrochloric acid, nitric acid or sulfuric acid solution, and the concentration is 1-6 mol / L.

[0011] In the above scheme, the solid-liquid ratio of the metal powder and the acidic aqueous solution is 2 mg: 5-40 μL.

[0012] In the above scheme, the state of the metal reaction being completed is that no granular solid is visible in the aqueous solution.

[0013] Further, the ultrasonic reaction time is 2-5 min.

[0014] In the above scheme, the nitrogen source can be selected from ammonia, hydrazine hydrate or hydroxylamine.

[0015] In the above scheme, the peroxide can be selected from hydrogen peroxide, tert-butyl hydroperoxide, peroxyformic acid or peroxyacetic acid water.

[0016] In the above scheme, the mass ratio of the introduced metal powder, graphene oxide, peroxide and nitrogen source is 1:(0.77-10):(1-5.56):(0.1-200).

[0017] In the above scheme, the diameter of the graphene oxide sheet is 10nm-40μm.

[0018] Further, the precursor solution is a mixture of graphene oxide dispersion, hydrogen peroxide aqueous solution, and nitrogen source; the concentration of the graphene oxide dispersion is 3-12 mg / L; the concentration of the hydrogen peroxide aqueous solution is 0.1-10 wt%; and the concentration of the nitrogen source is 20-30 wt%.

[0019] In the above scheme, the hydrothermal reaction is carried out at a temperature of 160-220℃ for a time of 6-12 hours.

[0020] In the above scheme, the dilute acid can be hydrochloric acid, nitric acid or sulfuric acid aqueous solution, etc., with a concentration of 1-6 mol / L.

[0021] In the above scheme, the mass ratio of the black hydrogel to the dilute acid is 1:1-5.

[0022] In the above scheme, the stirring treatment time is 1-12 hours and the rotation speed is 300-800 rpm.

[0023] The catalyst prepared according to the above scheme has a phthalocyanine-metal atomic structure with nitrogen-doped porous graphene sheets with a diameter of 10 nm-40 μm and a porous structure (pore size distribution of 2-10 nm). Its extended edge X-ray absorption structure is highly similar to that of phthalocyanine standard, and it has the advantages of easy electron transfer and stable active intermediate.

[0024] The phthalocyanine-metal atom structure catalyst was applied to the hydrogen transfer reaction of hydrazine hydrate on aromatic nitro groups; a good yield was maintained even under mild conditions where the molar ratio of hydrogen transfer agent to aromatic nitro compound was less than (5-10):1.

[0025] Furthermore, the mild hydrogen transfer agent may be selected from hydrazine hydrate or the like.

[0026] This invention uses a small amount of elemental metal (metal powder) as the metal source, which makes it easier to control the size of nanoparticles when loading them in situ on the surface of graphene oxide. After acid etching, it is easier to achieve precise control of the coordination environment of metal single atoms.

[0027] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0028] 1) Compared with expensive metal phthalocyanine compounds, this invention uses inexpensive metal powder as a metal source and anchors it on the active substrate graphene oxide in the form of fine nanoparticles, and promotes the construction of phthalocyanine-like structures, which greatly reduces the production cost of phthalocyanine structure catalysts and can provide a new idea for the preparation of high-performance catalysts.

[0029] 2) The metal atoms on the surface of the catalyst described in this invention are uniformly dispersed, which can exhibit excellent catalytic activity and maintain a good yield even when the molar ratio of mild hydrogen transfer agent to aromatic nitro compound is less than (5-10):1.

[0030] 3) The preparation method involved in this invention is relatively simple, has good repeatability, is easy to apply, and is suitable for widespread application. Attached Figure Description

[0031] Figure 1 This is a transmission electron microscope (TEM) image of the iron catalyst obtained in Example 1;

[0032] Figure 2 The image shows aberration-corrected scanning transmission electron microscope image of the catalyst obtained in Example 1.

[0033] Figure 3 The energy spectrum scan of the catalyst obtained in Example 1 is shown below.

[0034] Figure 4 The K-edge X-ray absorption near-edge spectrum of the catalyst obtained in Example 1;

[0035] Figure 5 The Fourier transform spectrum of the catalyst obtained in Example 1 is the Fe K edge-extended X-ray absorption fine structure spectrum.

[0036] Figure 6 The image shows a transmission electron microscope (TEM) image of the nano-iron catalyst obtained in Comparative Example 1.

[0037] Figure 7 Photograph of the solution color change of p-nitrophenol to p-aminophenol catalyzed by the catalyst obtained in Example 1;

[0038] Figure 8 The UV-Vis absorption curves of the solutions before and after the reduction of p-nitrophenol by the catalyst obtained in Example 1 are shown. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0040] In the following examples, the graphene oxide with a sheet diameter of 10 nm-40 μm used was prepared by a modified Hummers method. The reference is as follows: Preparation of graphic oxide. Journal of the American Chemical Society, 1958, 208, 1334-1339.

[0041] Example 1

[0042] A nitrogen-doped graphene-supported phthalocyanine-iron atom structure catalyst (Fe1-NHG) is prepared by the following steps:

[0043] 20 mg of iron powder with an average particle size of 1 μm was weighed out and added dropwise to 160 μL of 6 mol / L hydrochloric acid solution. After sonication for 1 min, 200 μL of 3 wt% hydrogen peroxide aqueous solution was added and sonicated for 30 s. Then, 3.5 mL of deionized water was added and mixed with 26 mL of a mixture of graphene oxide, hydrogen peroxide, and ammonia (the mass ratio of graphene oxide, hydrogen peroxide, NH3·H2O, and deionized water was 1:0.8:40:220). The mixture was stirred until it was evenly dispersed. After hydrothermal treatment at 180 °C for 6 h, the black hydrogel was washed until neutral. Then, 20 g of the obtained black hydrogel was added to 100 mL of 1 mol / L hydrochloric acid solution and stirred for 12 h (500 rpm). After washing until neutral, the nitrogen-doped graphene-supported phthalocyanine-iron atom structure catalyst was obtained.

[0044] The transmission electron microscope image of the catalyst with a phthalocyanine-iron atom structure prepared in this embodiment is shown below. Figure 1 The microstructure and oxidation etching of graphene can be observed.

[0045] Figure 2 In the aberration-corrected scanning transmission electron microscope, the white bright spots represent uniform and isolated iron single atoms with a size of approximately 2.5 angstroms.

[0046] Figure 3 The energy dispersive spectroscopy (EDS) spectrum confirms that the scheme described in Example 1 can successfully prepare a uniformly distributed iron single-atom catalyst. Furthermore, the synchrotron radiation analysis of the iron single-atom catalyst obtained in this example is shown in [reference needed]. Figure 4 The results showed that in the obtained catalyst product, iron single atoms were distributed in the form of ferrous iron on the surface of nitrogen-doped graphene.

[0047] Figure 5 R-space analysis of the prepared single-atom catalyst revealed no Fe-□Fe or Fe-□O bonds. Furthermore, strong signals were observed at 1.5 Å and 2.5 Å, consistent with the signals of the phthalocyanine iron standard. The product obtained in Example 1 achieved an R-space distribution similar in intensity to the phthalocyanine iron standard, enabling the effective construction of a phthalocyanine-iron atom-like structure.

[0048] Example 2

[0049] A nitrogen-doped graphene-supported phthalocyanine-iron atom structure catalyst (Fe1-NHG) is prepared by the following steps:

[0050] 20 mg of iron powder with an average particle size of 2 μm was weighed out and added dropwise to 100 μL of 6 mol / L nitric acid solution. The mixture was sonicated for 1 min, and then 200 μL of 3 wt% hydrogen peroxide aqueous solution was added. After sonication for 30 s, 3.5 mL of deionized water was added, and then the mixture was added to 26 mL of a mixture of graphene oxide, hydrogen peroxide, and ammonia (the mass ratio of graphene oxide, hydrogen peroxide, NH3·H2O, and deionized water was 1:0.8:40:220). The mixture was stirred until it was evenly dispersed. The mixture was hydrothermally heated at 180 °C for 6 h. After washing the black hydrogel until neutral, 20 g of the obtained black hydrogel was added to 100 mL of 1 mol / L nitric acid solution and stirred for 12 h (500 rpm). After washing until neutral, the nitrogen-doped graphene-supported phthalocyanine-iron atom structure catalyst was obtained.

[0051] Example 3

[0052] A nitrogen-doped graphene-supported phthalocyanine-iron atom structure catalyst (Fe1-NHG) is prepared by the following steps:

[0053] 20 mg of iron powder with an average particle size of 10 μm was weighed out and added dropwise to 80 μL of 6 mol / L sulfuric acid solution. The mixture was sonicated for 3 min, and then 200 μL of 3 wt% hydrogen peroxide aqueous solution was added. After sonication for 30 s, 3.5 mL of deionized water was added, and then the mixture was added to 26 mL of a mixture of graphene oxide, hydrogen peroxide, and ammonia (the mass ratio of graphene oxide, hydrogen peroxide, NH3·H2O, and deionized water was 1:0.8:40:220). The mixture was stirred until it was evenly dispersed. The mixture was hydrothermally heated at 180 °C for 6 h. The black hydrogel was washed until neutral, and then 20.5 g of the obtained black hydrogel was added to 100 mL of 1 mol / L sulfuric acid solution and stirred for 12 h (500 rpm). The mixture was washed until neutral and the final washing solution contained no sulfate ions, thus obtaining a nitrogen-doped graphene-supported phthalocyanine-iron atom structure catalyst.

[0054] Example 4

[0055] A nitrogen-doped graphene-supported phthalocyanine-cobalt atom structure catalyst (Co1-NHG) is prepared by the following steps:

[0056] 20 mg of cobalt powder with an average particle size of 1 μm was weighed out and added dropwise to 160 μL of 6 mol / L hydrochloric acid solution. After sonication for 1 min, 200 μL of 3 wt% hydrogen peroxide aqueous solution was added and sonicated for 30 s. Then, 3.5 mL of deionized water was added and mixed with 26 mL of a mixture of graphene oxide, hydrogen peroxide, and ammonia (the mass ratio of graphene oxide, hydrogen peroxide, NH3·H2O, and deionized water was 1:0.8:40:220). The mixture was stirred until it was evenly dispersed. After hydrothermal treatment at 180 °C for 6 h, the black hydrogel was washed until neutral. Then, 21 g of the obtained black hydrogel was added to 100 mL of 1 mol / L hydrochloric acid solution and stirred for 12 h (500 rpm). After washing until neutral, the nitrogen-doped graphene-supported phthalocyanine-cobalt atom structure catalyst was obtained.

[0057] Example 5

[0058] A nitrogen-doped graphene-supported phthalocyanine-cobalt atom structure catalyst (Co1-NHG) is prepared by the following steps:

[0059] 20 mg of cobalt powder with an average particle size of 5 μm was weighed out and added dropwise to 100 μL of 6 mol / L nitric acid solution. The mixture was sonicated for 1 min, and then 200 μL of 3 wt% hydrogen peroxide aqueous solution was added. After sonication for 30 s, 3.5 mL of deionized water was added, and then the mixture was added to 26 mL of a mixture of graphene oxide, hydrogen peroxide, and ammonia (the mass ratio of graphene oxide, hydrogen peroxide, NH3·H2O, and deionized water was 1:0.8:40:220). The mixture was stirred until it was evenly dispersed. The mixture was hydrothermally heated at 180 °C for 6 h. After washing the black hydrogel until neutral, 20.2 g of the obtained black hydrogel was added to 100 mL of 1 mol / L nitric acid solution and stirred for 12 h (500 rpm). After washing until neutral, the nitrogen-doped graphene-supported phthalocyanine-cobalt atom structure catalyst was obtained.

[0060] Example 6

[0061] A nitrogen-doped graphene-supported phthalocyanine-cobalt atom structure catalyst (Co1-NHG) is prepared by the following steps:

[0062] 20 mg of cobalt powder with an average particle size of 10 μm was weighed out and added dropwise to 80 μL of 6 mol / L sulfuric acid solution. The mixture was sonicated for 3 min, and then 200 μL of 3 wt% hydrogen peroxide aqueous solution was added. After sonication for 30 s, 3.5 mL of deionized water was added, and then the mixture was added to 26 mL of a mixture of graphene oxide, hydrogen peroxide, and ammonia (the mass ratio of graphene oxide, hydrogen peroxide, NH3·H2O, and deionized water was 1:0.8:40:220). The mixture was stirred until it was evenly dispersed. The mixture was hydrothermally heated at 180 °C for 6 h. After washing the black hydrogel until it was neutral, 20.5 g of the obtained black hydrogel was added to 100 mL of 1 mol / L sulfuric acid solution and stirred for 12 h (500 rpm). The mixture was washed until it was neutral and the final washing solution contained no sulfate ions, thus obtaining the nitrogen-doped graphene-supported phthalocyanine-cobalt atom structure catalyst.

[0063] Example 7

[0064] A nitrogen-doped graphene-supported phthalocyanine-nickel atom structure catalyst (Ni1-NHG) is prepared by the following steps:

[0065] 20 mg of nickel powder with an average particle size of 1 μm was weighed and added dropwise to 160 μL of 6 mol / L hydrochloric acid solution. After sonication for 1 min, 200 μL of 3 wt% hydrogen peroxide aqueous solution was added and sonicated for 30 s. Then, 3.5 mL of deionized water was added and mixed with 26 mL of a mixture of graphene oxide, hydrogen peroxide, and ammonia (the mass ratio of graphene oxide, hydrogen peroxide, NH3·H2O, and deionized water was 1:0.8:40:220). The mixture was stirred until it was evenly dispersed. After hydrothermal treatment at 180 °C for 6 h, the black hydrogel was washed until neutral. Then, 20.5 g of the obtained black hydrogel was added to 100 mL of 1 mol / L hydrochloric acid solution and stirred for 12 h (500 rpm). After washing until neutral, the nitrogen-doped graphene-supported phthalocyanine-nickel atom structure catalyst was obtained.

[0066] Example 8

[0067] A nitrogen-doped graphene-supported phthalocyanine-nickel atom structure catalyst (Ni1-NHG) is prepared by the following steps:

[0068] 20 mg of nickel powder with an average particle size of 1 μm was weighed out and added dropwise to 80 μL of 6 mol / L nitric acid solution. The mixture was sonicated for 1 min, and then 200 μL of 3 wt% hydrogen peroxide aqueous solution was added. After sonication for 30 s, 3.5 mL of deionized water was added, and then the mixture was added to 26 mL of a mixture of graphene oxide, hydrogen peroxide, and ammonia (the mass ratio of graphene oxide, hydrogen peroxide, NH3·H2O, and deionized water was 1:0.8:40:220). The mixture was stirred until it was evenly dispersed. The mixture was hydrothermally heated at 180 °C for 6 h. After washing the black hydrogel until neutral, 20.8 g of the obtained black hydrogel was added to 100 mL of 1 mol / L nitric acid solution and stirred for 12 h (500 rpm). After washing until neutral, the nitrogen-doped graphene-supported phthalocyanine-nickel atom structure catalyst was obtained.

[0069] Example 9

[0070] A nitrogen-doped graphene-supported phthalocyanine-nickel atom structure catalyst (Ni1-NHG) is prepared by the following steps:

[0071] 20 mg of nickel powder with an average particle size of 10 μm was weighed out and added dropwise to 80 μL of 6 mol / L sulfuric acid solution. The mixture was sonicated for 3 min, and then 200 μL of 3 wt% hydrogen peroxide aqueous solution was added. After sonication for 30 s, 3.5 mL of deionized water was added, and then the mixture was added to 26 mL of a mixture of graphene oxide, hydrogen peroxide, and ammonia (the mass ratio of graphene oxide, hydrogen peroxide, NH3·H2O, and deionized water was 1:0.8:40:220). The mixture was stirred until it was evenly dispersed. The mixture was hydrothermally heated at 180 °C for 6 h. The black hydrogel was washed until neutral, and then 20.3 g of the obtained black hydrogel was added to 100 mL of 1 mol / L sulfuric acid solution and stirred for 12 h (500 rpm). The mixture was washed until neutral and the final washing solution contained no sulfate ions, thus obtaining the nitrogen-doped graphene-supported phthalocyanine-nickel atom structure catalyst.

[0072] Example 10

[0073] A nitrogen-doped graphene-supported phthalocyanine-like iron-cobalt-nickel three-atom catalyst (FeCoNi-NHG) is prepared by the following steps:

[0074] 20 mg each of iron powder, cobalt powder, and nickel powder with an average particle size of 1 μm were weighed and added dropwise to 160 μL of 6 mol / L hydrochloric acid solution. After sonication for 1 min, 66 μL of 3 wt% hydrogen peroxide aqueous solution was added to each, and after sonication for 30 s, 1.2 mL of deionized water was added to each. The mixture was then added to 26 mL of a mixture of graphene oxide, hydrogen peroxide, and ammonia (the mass ratio of graphene oxide, hydrogen peroxide, NH3·H2O, and deionized water was 1:0.8:40:220), and stirred until uniformly dispersed. The mixture was hydrothermally heated at 180 °C for 6 h. After washing the black hydrogel to neutrality, 20.1 g of the obtained black hydrogel was added to 100 mL of 1 mol / L hydrochloric acid solution and stirred for 12 h (500 rpm). After washing to neutrality, the nitrogen-doped graphene-supported phthalocyanine-like iron-cobalt-nickel triatomic catalyst was obtained.

[0075] Example 11

[0076] A nitrogen-doped graphene-supported phthalocyanine-like iron-cobalt-nickel three-atom catalyst (FeCoNi-NHG) is prepared by the following steps:

[0077] 20 mg each of iron powder, cobalt powder, and nickel powder with an average particle size of 1 μm were weighed out and added dropwise to 80 μL of 6 mol / L nitric acid solution. After sonication for 1 min, 66 μL of 3 wt% hydrogen peroxide aqueous solution was added to each, and after sonication for 30 s, 1.2 mL of deionized water was added to each. The mixture was then added to 26 mL of a mixture of graphene oxide, hydrogen peroxide, and ammonia (the mass ratio of graphene oxide, hydrogen peroxide, NH3·H2O, and deionized water was 1:0.8:40:220), and stirred until uniformly dispersed. The mixture was hydrothermally heated at 180 °C for 6 h. After washing the black hydrogel until neutral, 20 g of the obtained black hydrogel was added to 100 mL of 1 mol / L nitric acid solution and stirred for 12 h (500 rpm). After washing until neutral, the nitrogen-doped graphene-supported phthalocyanine-like iron-cobalt-nickel triatomic catalyst was obtained.

[0078] Example 12

[0079] A nitrogen-doped graphene-supported phthalocyanine-like iron-cobalt-nickel three-atom catalyst (FeCoNi-NHG) is prepared by the following steps:

[0080] 20 mg each of iron powder, cobalt powder, and nickel powder with an average particle size of 1 μm were weighed out and added dropwise to 80 μL of 6 mol / L sulfuric acid solution. After sonication for 1 min, 66 μL of 3 wt% hydrogen peroxide aqueous solution was added to each, and after sonication for 30 s, 1.2 mL of deionized water was added to each. The mixture was then added to 26 mL of a mixture of graphene oxide, hydrogen peroxide, and ammonia (the mass ratio of graphene oxide, hydrogen peroxide, NH3·H2O, and deionized water was 1:0.8:40:220), and stirred until uniformly dispersed. The mixture was hydrothermally heated at 180 °C for 6 h. The black hydrogel was washed until neutral, and then 20.8 g of the obtained black hydrogel was added to 100 mL of 1 mol / L sulfuric acid solution and stirred for 12 h (500 rpm). After washing until neutral, the nitrogen-doped graphene-supported phthalocyanine-like iron-cobalt-nickel triatomic catalyst was obtained.

[0081] Comparative Example 1

[0082] A nitrogen-doped graphene-supported nanoparticle catalyst is prepared using a method largely the same as in Example 1, except that it does not undergo dilute acid post-treatment. The specific preparation method is as follows:

[0083] Weigh out 20 mg of iron powder with an average particle size of 1 μm, add 80 μL of 6 mol / L hydrochloric acid solution, sonicate for 1 min, add 200 μL of 3 wt% hydrogen peroxide aqueous solution, sonicate for 30 s, add 3.5 mL of deionized water, and then add to a 26 mL mixture of graphene oxide, hydrogen peroxide, and ammonia (the mass ratio of graphene oxide, hydrogen peroxide, NH3·H2O, and deionized water is 1:0.8:40:220). Stir until uniformly dispersed. Perform hydrothermal treatment at 180 °C for 6 h, and finally wash the black hydrogel (nanoparticle-type iron catalyst) until neutral.

[0084] The transmission electron microscope image of the supported iron catalyst obtained in this comparative example is shown below. Figure 6 The average particle size of the nanoparticles is 11.18 nm. It can be seen that the absence of dilute acid etching results in more black particles (iron nanoparticles) being distributed on the surface of nitrogen-doped graphene. At this time, the metal utilization rate is low and the cycle stability is poor.

[0085] Application Example 1

[0086] In a 10 mL methanol solution of p-nitrophenol (20 mmol / L), 40 μL of hydrazine hydrate (molar ratio of hydrazine hydrate to aromatic nitro compound was 5:1) was added, and the solution turned bright yellow. Then, 5 mg of the catalyst with a phthalocyanine-like metal structure prepared in Example 1 was added, and after 500 s, the solution turned colorless, indicating that p-nitrophenol was reduced to p-aminophenol. The catalytic effect of the iron single-atom catalyst in the catalytic hydrogenation reduction of p-nitrophenol was further verified by UV-Vis absorption spectroscopy. After the catalytic reaction, the characteristic absorption peak of p-nitrophenol disappeared, and a new absorption peak of p-aminophenol appeared (see...). Figure 8 ).

[0087] Application Example 2

[0088] In a 10 mL methanol-water mixed solution of p-nitrophenol (20 mmol / L), the addition of 378 mg (50 equivalents) of sodium borohydride turned the solution bright yellow. Upon addition of 5 mg of the catalyst obtained in Example 1, the solution became colorless after 180 s (see...). Figure 7 This indicates that p-nitrophenol was reduced to p-aminophenol.

[0089] Application Example 3

[0090] 0.2 mmol of p-nitrobenzoic acid, p-nitrotoluene, p-nitroanisole, p-nitroaniline, p-nitrochlorobenzene, m-nitrochlorobenzene, p-nitrobromobenzene, m-nitrobromobenzene, p-nitrobenzonitrile, and nitrobenzene were dissolved in 10 mL of methanol. 40 μL of hydrazine hydrate was added, along with 5 mg of the catalyst obtained in Example 1. The mixture was heated at 60 °C, and after a period of time, the products were analyzed by high performance liquid chromatography (HPLC). The obtained products were all single and the yields all exceeded 90%; see Table 1 for details.

[0091] Table 1. Application effects of the nitrogen-doped graphene-supported phthalocyanine-like single-atom catalyst described in this invention.

[0092]

[0093]

[0094] Application Example 4

[0095] In a 10 mL methanol solution of p-nitrophenol (20 mmol / L), 40 μL of hydrazine hydrate (5 equivalents) was added, and the solution turned bright yellow. Then, 5 mg of the catalyst obtained in Example 1 was added, and after 500 s, the solution became colorless, indicating that p-nitrophenol was reduced to p-aminophenol. The added catalyst was filtered, washed, dried, and then added back to the same reaction system. After five catalytic cycles, the catalytic time did not decrease significantly.

[0096] In the same reaction system, 5 mg of the nanoparticle iron catalyst prepared in Comparative Example 1 was added. After 500 s, the solution turned colorless, indicating that p-nitrophenol was reduced to p-aminophenol. The added catalyst was filtered, washed, and dried, and then added to the same reaction system again. After three catalytic cycles, the catalytic time was extended to 650 s, proving that the stability of the nanoparticle iron catalyst prepared in Comparative Example 1 was worse than that of the catalyst with a phthalocyanine-like metal atomic structure prepared in Example 1.

[0097] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and its improved concept, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing a catalyst with a phthalocyanine-metal atom structure, characterized in that, The process includes the following steps: mixing metal powder with an acidic aqueous solution and subjecting it to an ultrasonic reaction, then adding it to a precursor solution containing graphene oxide, peroxide, and a nitrogen source, and performing a hydrothermal reaction to obtain a black hydrogel, followed by washing. The black hydrogel was stirred in dilute acid and washed to obtain the catalyst with a phthalocyanine-metal atom structure. The metal powder is one or more of iron powder, cobalt powder, and nickel powder; The dilute acid is an aqueous solution of hydrochloric acid, nitric acid, or sulfuric acid, with a concentration of 1-6 mol / L; The stirring process takes 1-12 hours and rotates at 300-800 rpm.

2. The preparation method according to claim 1, characterized in that, The metal powder has a particle size of 1-10 μm; the acidic aqueous solution is hydrochloric acid, nitric acid, or sulfuric acid solution with a concentration of 1-6 mol / L; the nitrogen source is ammonia, hydrazine hydrate, or hydroxylamine; the peroxide is hydrogen peroxide, tert-butyl hydrogen peroxide, peroxyformic acid, or peracetic acid; and the graphene oxide has a sheet diameter of 10 nm-40 μm.

3. The preparation method according to claim 1, characterized in that, The solid-liquid ratio of the metal powder to the acidic aqueous solution is 2 mg: 2.5-40 μL.

4. The preparation method according to claim 1, characterized in that, The mass ratio of the introduced metal powder, graphene oxide, peroxide, and nitrogen source is 1: (0.77-10): (1-5.56): (0.1-10).

5. The preparation method according to claim 1, characterized in that, The hydrothermal reaction is carried out at a temperature of 160-220℃ for a time of 6-12 hours.

6. The preparation method according to claim 1, characterized in that, The mass ratio of the black hydrogel to the dilute acid is 1:1-5.

7. The phthalocyanine-metal atom structure catalyst prepared by the preparation method according to any one of claims 1 to 6.

8. The application of the phthalocyanine-metal atom structure catalyst of claim 7 in the field of hydrogen transfer reaction.

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