Iron-based sulfide with hierarchical structure and preparation method and application thereof

Abstract

The application belongs to the technical field of transition metal catalysts, and discloses an iron-based sulfide with a hierarchical structure and a preparation method and application thereof. The preparation method comprises the following steps: reacting an iron source and diethyl dithiocarbamate in an aqueous solution, collecting and drying the precipitate to obtain iron diethyl dithiocarbamate; dispersing the iron diethyl dithiocarbamate in anhydrous ethylenediamine for a solvothermal reaction, collecting and drying the precipitate to obtain a precursor; dispersing the precursor in water, adding an organic exchanger for ion exchange, collecting and drying the precipitate, and the iron-based sulfide with a hierarchical structure is obtained. The specific surface area of the iron-based sulfide with a hierarchical structure is significantly increased, the exposed active sites are greatly increased, and the catalytic efficiency and selectivity of hydrazine hydrate in reducing nitroaromatic hydrocarbons are improved. The catalytic conversion rate of different nitroaromatic hydrocarbons is greater than 91%, and the highest can reach 100%, and the selectivity is greater than 99%.

Description

Technical Field

[0001] This application belongs to the field of transition metal catalyst technology, specifically relating to an iron-based sulfide with a hierarchical structure, its preparation method, and its application. Background Technology

[0002] The reduction of nitroaromatics is a very important class of reactions in industry. The reduction products, aromatic amines, are important chemical raw materials and intermediates with wide applications in dyes, pharmaceuticals, pesticides, textiles, and photosensitive materials. Currently, the main methods for reducing nitroaromatics include catalytic hydrogenation, electrochemical reduction, sodium sulfide reduction, and hydrazine hydrate reduction. Among these, hydrazine hydrate reduction is a green and environmentally friendly method, requiring no high-pressure hydrogen gas but using hydrazine hydrate as the hydrogen source. It has advantages such as mild reaction conditions, low energy consumption, and no pollution from hydrazine decomposition products.

[0003] In the hydrazine hydrate reduction process, hydrazine hydrate needs to release active hydrogen with the assistance of a catalyst to achieve efficient reduction of nitroaromatics. Iron is one of the most abundant elements on Earth, with advantages such as low price and non-toxicity. Existing research has demonstrated that iron-based catalysts have great potential in catalyzing the reduction of nitroaromatics by hydrazine hydrate.

[0004] Current iron-based catalysts are mainly Fe2O3, Fe3O4, and Fe-CN materials. Research on iron-based sulfides is scarce. The few reports (New Journal of Chemistry, 2021, 45, 17808; Applied Organometallic Chemistry, 2021, 35, e6294) involve iron-based sulfides such as particulate or blocky FeS2 and Fe7S8. These are low-dimensional iron-based sulfides with simple structures and uncontrollable morphology, resulting in few active sites and low catalytic efficiency. Summary of the Invention

[0005] This application provides an iron-based sulfide with a hierarchical structure, its preparation method, and its application, aiming to solve the technical problem of low catalytic efficiency caused by the simple structure, uncontrollable morphology, and few active sites of existing iron-based sulfides.

[0006] To achieve the above objectives, the present application adopts the following technical solution.

[0007] A first aspect of this application provides a method for preparing an iron-based sulfide with a hierarchical structure, comprising the following steps:

[0008] Step 1: The iron source and diethyldithiocarbamate are reacted in an aqueous solution, the precipitate is collected and dried to obtain iron diethyldithiocarbamate.

[0009] Step 2: The iron diethyldithiocarbamate is dispersed in anhydrous ethylenediamine and subjected to a solvothermal reaction. The precipitate is collected and dried to obtain the precursor.

[0010] Step 3: Disperse the precursor in water, add an organic exchanger for ion exchange, collect the precipitate, and dry it to obtain the final product.

[0011] In some embodiments, the iron source is one or more of ferric chloride, ferric sulfate, ferric nitrate, ferric chloride hydrate, ferric sulfate hydrate, or ferric nitrate hydrate.

[0012] In some embodiments, the diethyldithiocarbamate is one or more of sodium diethyldithiocarbamate, potassium diethyldithiocarbamate, sodium diethyldithiocarbamate hydrate, or potassium diethyldithiocarbamate hydrate.

[0013] In some embodiments, the weight-to-volume ratio of the iron diethyldithiocarbamate to the anhydrous ethylenediamine is 1 g / 30-50 mL.

[0014] In some embodiments, the mass ratio of the precursor to the organic exchanger is 1:(0.5 to 1.5).

[0015] In some embodiments, the organic exchanger is tris(hydroxymethyl)aminomethane.

[0016] In some embodiments, the temperature of the solvothermal reaction is 140–180°C.

[0017] Another aspect of this application provides an iron-based sulfide with a hierarchical structure prepared by the above-described preparation method.

[0018] Another aspect of this application provides the application of the aforementioned iron-based sulfides with hierarchical structures in catalysts.

[0019] Another aspect of this application provides a catalyst for the reduction of nitroaromatics, comprising the aforementioned iron-based sulfides having a hierarchical structure.

[0020] Compared with the prior art, the beneficial effects of this application are as follows:

[0021] In the method for preparing iron-based sulfides with hierarchical structures in this application, during the solvothermal reaction of iron diethyldithiocarbamate with the nucleophile ethylenediamine, ethylenediamine attacks the carbon atoms on the sulfur carbonyl group, causing some CNEt2 encapsulation groups to detach and form exposed Et2NCS2-Fe-S sites. After combining, these sites form iron-sulfur clusters with a cuboethane cluster structure and alternating Fe and S atoms at the vertices, exhibiting a rod-like morphological structure. During the ion exchange process of tris(hydroxymethyl)aminomethane on the rod-like iron-sulfur clusters, the lone electrons of the NH2 group of tris(hydroxymethyl)aminomethane reduce the oxidation state of Fe in the cluster skeleton of the outer rod-like iron-sulfur clusters, weakening the Fe-S bond. Subsequently, the bond breaks, and O in tris(hydroxymethyl)aminomethane replaces some S, transforming the outer layer of the rod-like iron-sulfur clusters from a cuboethane cluster structure to a chain-like cluster structure, exhibiting a plate-like morphological structure, thus giving the iron-based sulfides a hierarchical structure.

[0022] The iron-based sulfide with a hierarchical structure of this application has a significantly increased specific surface area, which greatly increases the number of exposed active sites, thereby improving the catalytic efficiency and selectivity of hydrazine hydrate reduction of nitroaromatics. The catalytic conversion rate of different nitroaromatics is greater than 91%, and can reach up to 100%, with a selectivity greater than 99%. Attached Figure Description

[0023] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 The SEM image of iron diethyldithiocarbamate provided in Example 1;

[0025] Figure 2 SEM and TEM spectra of the precursor provided in Example 1;

[0026] Figure 3 EDS spectrum of the precursor provided in Example 1;

[0027] Figure 4 SEM and TEM spectra of the iron-based sulfides with hierarchical structures provided in Example 1;

[0028] Figure 5 XRD pattern of iron-based sulfides with hierarchical structure provided in Example 1;

[0029] Figure 6 Nitrogen adsorption-desorption curves of the precursor and the iron-based sulfide with a hierarchical structure provided in Example 1;

[0030] Figure 7 TEM spectrum of iron-based sulfides provided for Comparative Example 1;

[0031] Figure 8 TEM spectrum of iron-based sulfides provided for Comparative Example 2. Detailed Implementation

[0032] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0033] In the following description of this embodiment, the terms "including", "comprising", "having", and "containing" are all open-ended terms, meaning that they include but are not limited to.

[0034] In the following description of this embodiment, the term "and / or" is used to describe the association relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, B existing alone, and A and B existing simultaneously. A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0035] In the following description of this embodiment, the term "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple.

[0036] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms "a" and "the" as used in the embodiments of this application and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise.

[0037] Those skilled in the art should understand that, in the following description of the embodiments of this application, the sequence of numbers does not imply the order of execution. Some or all steps may be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0038] Those skilled in the art will understand that the numerical ranges in the embodiments of this application should be understood to specifically disclose each intermediate value between the upper and lower limits of the range. Each smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this application. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0039] Unless otherwise stated, the technical / scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. While this application describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this application. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0040] A first aspect of this application provides a method for preparing the aforementioned iron-based sulfide with a hierarchical structure, comprising the following steps:

[0041] Step 1: Mix and stir the aqueous solution of iron source and the aqueous solution of diethyldithiocarbamate, collect the precipitate and dry it to obtain iron diethyldithiocarbamate.

[0042] The iron source is one or a mixture of ferric chloride, ferric sulfate, ferric nitrate, ferric chloride hydrate, ferric sulfate hydrate, or ferric nitrate hydrate; the diethyldithiocarbamate is one or a mixture of sodium diethyldithiocarbamate, potassium diethyldithiocarbamate, sodium diethyldithiocarbamate hydrate, or potassium diethyldithiocarbamate hydrate. It should be noted that the iron salts and diethyldithiocarbamates in this application include, but are not limited to, the above-mentioned compounds. Combinations of other iron compounds capable of preparing ferric diethyldithiocarbamate with diethyldithiocarbamate are also within the scope of protection of this application.

[0043] The iron diethyldithiocarbamate has a clustered aggregate structure and is brownish-black in appearance.

[0044] Step 2: The iron diethyldithiocarbamate is dispersed in anhydrous ethylenediamine and subjected to a solvothermal reaction. The precipitate is collected and dried to obtain the precursor.

[0045] The solvothermal reaction temperature is 140–180℃, such as 140℃, 150℃, 160℃, 170℃, or 180℃. In the solvothermal reaction, the weight-to-volume ratio of the iron diethyldithiocarbamate to the anhydrous ethylenediamine is 1 g / 30–50 mL, such as 1 g / 30 mL, 1 g / 40 mL, 1 g / 50 mL, or any ratio within this range. Under the action of anhydrous ethylenediamine, some of the CNEt2 ligand groups in the clustered Fe(S2CNEt2)3 detach, forming exposed Et2NCS2-Fe-S sites, and the precursor transforms into a rod-like structure.

[0046] Step 3: Disperse the precursor in water, add an organic exchanger for ion exchange, collect the precipitate, and dry it to obtain the final product.

[0047] The organic exchanger is trihydroxymethylaminomethane. The NH2 in trihydroxymethylaminomethane has a lone pair of electrons, which can act as a reducing agent to reduce the oxidation state of Fe in the clusters of the rod-shaped iron-sulfur clusters on the outer layer of the precursor, weakening the Fe-S bond. Subsequently, the bond breaks, and the O in trihydroxymethylaminomethane replaces part of the S. The outer layer of the rod-shaped iron-sulfur cluster changes from a cubane cluster structure to a chain cluster structure, and the morphological structure is plate-like, giving the iron-based sulfide a hierarchical structure.

[0048] The hierarchical structure described in this application is a regular and ordered three-dimensional structure assembled from simple low-dimensional nanostructures as the main building blocks in a specific arrangement. This can reduce material aggregation and expose more active sites. In this application, the hierarchical structure uses nanosheets as the main building blocks, which are uniformly arranged and distributed on the outer layer of a rod-shaped structure to assemble into a regular and ordered three-dimensional structure.

[0049] In this application, the mass ratio of the precursor to the organic exchanger is 1:(0.5 to 1.5), such as 1:0.5, 1:1, 1:1.5, or any ratio within this range. Within this range, a good hierarchical structure can be obtained. When there is too much organic exchanger, the rod-like structure of the iron-based sulfide collapses; while when there is too little exchanger, it is difficult to form a hierarchical structure.

[0050] This application also provides iron-based sulfides with hierarchical structures prepared by the above-described method, wherein nanosheets, as the main building blocks, are uniformly arranged and distributed on the outer layer of the rod-shaped structure, assembling into a regular and ordered three-dimensional structure. The hierarchical structure significantly increases the specific surface area of ​​the iron-based sulfides, greatly increasing the exposed active sites, thereby improving the catalytic efficiency and selectivity of hydrazine hydrate reduction of nitroaromatics.

[0051] The iron-based sulfides with hierarchical structures provided in this application can be used as catalysts for the reduction of nitroaromatics by hydrazine hydrate reduction. The catalytic conversion rates for different nitroaromatics are all greater than 91%, and can reach up to 100%, with a selectivity greater than 99%.

[0052] This application also provides a catalyst for the reduction of nitroaromatics, the catalyst comprising the iron-based sulfide with a hierarchical structure provided in this application, which can be used to catalyze the reduction of nitroaromatics or nitrobenzene derivatives, both of which have excellent catalytic conversion and selectivity.

[0053] The present application will be further illustrated by the following examples.

[0054] Example 1

[0055] This embodiment provides a method for preparing iron-based sulfides with a hierarchical structure, including:

[0056] Step 1: Dissolve 10 mmol of ferric chloride hexahydrate in 20 mL of water to prepare solution 1, and dissolve 30 mmol of sodium diethyldithiocarbamate trihydrate in 20 mL of water to prepare solution 2. Mix the two solutions, stir for 15 min, centrifuge at 8000 rpm for 2 min in a high-speed centrifuge, collect the substrate solid, and dry it in a 60℃ forced-air drying oven to obtain brownish-black iron diethyldithiocarbamate with the chemical formula Fe(S2CNEt2)3.

[0057] Step 2: Take 1g of ferric diethyldithiocarbamate and disperse it evenly in 40mL of anhydrous ethylenediamine. Then transfer it to a tetrafluoroethylene reactor, seal it, and react it in a solvothermal environment at 180℃ for 24h. Centrifuge the reaction product at 8000rpm for 2min in a high-speed centrifuge. Wash the resulting brown solid with water three times and dry it in a forced-air drying oven at 40℃ to obtain the precursor.

[0058] Step 3: Disperse 100 mg of the precursor evenly in 80 mL of water, add 120 mg of tris(hydroxymethyl)aminomethane, and stir for 24 h. Centrifuge the reaction product at 8000 rpm for 2 min in a high-speed centrifuge, wash the obtained solid twice with water, and dry it in a vacuum drying oven at 40 °C to obtain the iron-based sulfide with a hierarchical structure.

[0059] The iron diethyldithiocarbamate prepared in step 1 was subjected to SEM analysis, and its SEM spectrum is shown below. Figure 1 As shown, iron diethyldithiocarbamate has a clustered aggregate structure with a size of approximately 25 μm.

[0060] The precursor prepared in step 2 was subjected to SEM and TEM tests, and its spectrum is shown below. Figure 2As shown, a is its SEM spectrum, and b is its TEM spectrum. Figure 2 It can be seen that the precursor has a rod-shaped structure with a diameter of 200–500 nm.

[0061] The precursor was subjected to EDS testing, and its EDS spectrum is shown below. Figure 3 As shown, Fe, S, C, and N atoms are uniformly distributed on the nanorod structure, with an atomic ratio of Fe to S of approximately 1:2. Test results indicate that, under the influence of ethylenediamine, some of the CNEt2 ligand groups in the clustered Fe(S2CNEt2)3 detach and transform into a rod-shaped structure.

[0062] The iron-based sulfide with a hierarchical structure prepared in step 4 was subjected to SEM and TEM tests, and its spectrum is shown in the figure below. Figure 4 As shown, a is its SEM spectrum, and b is its TEM spectrum. Figure 4 It can be seen that after treatment with tris(hydroxymethyl)aminomethane, the precursor changes from a simple rod-shaped structure to a hierarchical structure with axial rod-shaped structure and radially grown nanosheets.

[0063] The iron-based sulfide with a hierarchical structure prepared in step 4 was subjected to XRD analysis, such as... Figure 5 As shown, iron-based sulfides with hierarchical structures exist in an amorphous form.

[0064] Nitrogen adsorption tests were performed on the precursor prepared in step 3 and the iron-based sulfide with a hierarchical structure prepared in step 4. The test results are as follows: Figure 6 As shown. From Figure 6 It is evident that iron-based sulfides with a hierarchical structure exhibit significantly higher adsorption capacity compared to rod-shaped precursors without a hierarchical structure, and the adsorption capacity increases rapidly at a relative pressure of 0.95. The test results indicate that the specific surface area of ​​iron-based sulfides with a hierarchical structure is substantially increased, resulting in a greater number of exposed active sites.

[0065] Example 2

[0066] This embodiment provides a method for preparing iron-based sulfides with a hierarchical structure, including:

[0067] Step 1: Dissolve 10 mmol of ferric chloride hexahydrate in 20 mL of water to prepare solution 1, and dissolve 30 mmol of sodium diethyldithiocarbamate trihydrate in 20 mL of water to prepare solution 2. Mix the two solutions, stir for 15 min, centrifuge at 8000 rpm for 2 min in a high-speed centrifuge, collect the substrate solid, and dry it in a 60℃ forced-air drying oven to obtain brownish-black iron diethyldithiocarbamate with the chemical formula Fe(S2CNEt2)3.

[0068] Step 2: Take 1g of ferric diethyldithiocarbamate and disperse it evenly in 30mL of anhydrous ethylenediamine. Then transfer it to a tetrafluoroethylene reactor, seal it, and react it in a solvothermal environment at 180℃ for 24h. Centrifuge the reaction product at 8000rpm for 2min in a high-speed centrifuge. Wash the resulting brown solid with water three times and dry it in a forced-air drying oven at 40℃ to obtain the precursor.

[0069] Step 3: Disperse 100 mg of the precursor evenly in 80 mL of water, add 50 mg of tris(hydroxymethyl)aminomethane, and stir for 24 h. Centrifuge the reaction product at 8000 rpm for 2 min in a high-speed centrifuge, wash the obtained solid twice with water, and dry it in a vacuum drying oven at 40 °C to obtain the iron-based sulfide with a hierarchical structure.

[0070] Example 3

[0071] This embodiment provides a method for preparing iron-based sulfides with a hierarchical structure, including:

[0072] Step 1: Dissolve 10 mmol of ferric chloride hexahydrate in 20 mL of water to prepare solution 1, and dissolve 30 mmol of sodium diethyldithiocarbamate trihydrate in 20 mL of water to prepare solution 2. Mix the two solutions, stir for 15 min, centrifuge at 8000 rpm for 2 min in a high-speed centrifuge, collect the substrate solid, and dry it in a 60℃ forced-air drying oven to obtain brownish-black iron diethyldithiocarbamate with the chemical formula Fe(S2CNEt2)3.

[0073] Step 2: Take 1g of ferric diethyldithiocarbamate and disperse it evenly in 50mL of anhydrous ethylenediamine. Then transfer it to a tetrafluoroethylene reactor, seal it, and react it in a solvothermal environment at 180℃ for 24h. Centrifuge the reaction product at 8000rpm for 2min in a high-speed centrifuge. Wash the resulting brown solid with water three times and dry it in a forced-air drying oven at 40℃ to obtain the precursor.

[0074] Step 3: Disperse 100 mg of the precursor evenly in 80 mL of water, add 150 mg of tris(hydroxymethyl)aminomethane, and stir for 24 h. Centrifuge the reaction product at 8000 rpm for 2 min in a high-speed centrifuge, wash the obtained solid twice with water, and dry it in a vacuum drying oven at 40 °C to obtain the iron-based sulfide with a hierarchical structure.

[0075] Comparative Example 1

[0076] The difference between Comparative Example 1 and Example 1 is that the organic exchanger was replaced with a poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymer, while all other aspects were the same as in Example 1.

[0077] The iron-based sulfides prepared in Comparative Example 1 were subjected to TEM testing, such as... Figure 7 As shown, most of the rod-like structure of the precursor collapses into nanosheets and cannot form an ordered hierarchical structure.

[0078] Comparative Example 2

[0079] The difference between Comparative Example 2 and Example 1 is that the organic exchanger was replaced with a mixture of tris(hydroxymethyl)aminomethane and polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer, while the rest were the same as in Example 1.

[0080] The iron-based sulfides prepared in Comparative Example 2 were subjected to TEM testing, such as... Figure 8 As shown, most of the rod-like structure of the precursor collapses into nanosheets, and it is also unable to form an ordered hierarchical structure.

[0081] The iron-based sulfides from Examples 1, 1, and 2 were used to catalyze the reduction of nitrobenzene by hydrazine hydrate. The specific steps were as follows: 1 mmol of nitrobenzene, 3.5 mmol of hydrazine hydrate, 10 mg of catalyst, and 5 mL of ethanol were sequentially added to a pressure-resistant reaction flask. The mixture was stirred at 80°C for 1.5 h. After the reaction was stopped, the catalyst was removed using a microporous membrane. The product was analyzed by gas chromatography using the internal standard method (anisole as the internal standard), and the results are shown in Table 1.

[0082] Table 1 Catalytic data for three iron-based sulfides

[0083] Serial Number catalyst Conversion rate (%) Selectivity (%) 1 Example 1 100 99.9 2 Example 2 58 85.8 3 Example 3 79 89.9

[0084] As shown in Table 1, the iron-based sulfide with a hierarchical structure prepared in Example 1 of this application exhibits the best catalytic effect, with a nitrobenzene conversion rate of 100%, which is significantly higher than that of the iron-based sulfides in Comparative Examples 1 and 2. The aniline selectivity reaches 99.9%, also significantly higher than that of the iron-based sulfides in Comparative Examples 1 and 2.

[0085] The iron-based sulfide with a hierarchical structure obtained in Example 1 was used to catalyze the reduction of nitrobenzene derivatives by hydrazine hydrate. The specific steps were as follows: 1 mmol of nitrobenzene derivative, 3.5 mmol of hydrazine hydrate, 10 mg of catalyst, and 5 mL of ethanol were sequentially added to a pressure-resistant reaction flask. The mixture was stirred at 80°C for a certain time. After the reaction was stopped, the catalyst was removed using a microporous membrane. The nitrobenzene derivatives included, but were not limited to, 4-chloronitrobenzene, 2-chloronitrobenzene, 4-bromonitrobenzene, 4-iodonitrobenzene, 4-nitrophenol, 4-nitroanisole, 4-methyl-2-nitroaniline, and ethyl p-nitrobenzene. After the nitrobenzene derivatives were reduced, the products were analyzed by gas chromatography using the internal standard method (anisole as the internal standard). The results are shown in Table 2.

[0086] Table 2 Catalytic data of iron-based sulfides with hierarchical structures catalyzing different nitrobenzene derivatives.

[0087]

[0088] As can be seen from the data in Table 2, the iron-based sulfides with hierarchical structure of this application have excellent conversion and selectivity for the reduction of different nitrobenzene derivatives. The conversion rates are all greater than 91%, and the highest can reach more than 99%. Except for the selectivity of 97.8% for the reduction of 4-iodonitrobenzene, the selectivity for the other nitrobenzene derivatives is greater than 99%.

[0089] Although this application has been described in detail in this specification with general descriptions and specific embodiments, some modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, such modifications or improvements made without departing from the spirit of this application are all within the scope of protection claimed in this application.

Claims

1. A method for preparing iron-based sulfides with a hierarchical structure, characterized in that, Includes the following steps: Step 1: The iron source and diethyldithiocarbamate are reacted in an aqueous solution, the precipitate is collected and dried to obtain iron diethyldithiocarbamate. Step 2: The iron diethyldithiocarbamate is dispersed in anhydrous ethylenediamine and subjected to a solvothermal reaction. The precipitate is collected and dried to obtain the precursor. Step 3: Disperse the precursor in water, add an organic exchanger for ion exchange, collect the precipitate, and dry it to obtain the final product; The organic exchanger is tris(hydroxymethyl)aminomethane; the mass ratio of the precursor to the organic exchanger is 1:(0.5~1.5).

2. The method for preparing iron-based sulfides with a hierarchical structure according to claim 1, characterized in that, The iron source is one or a mixture of ferric chloride, ferric sulfate, or ferric nitrate.

3. The method for preparing iron-based sulfides with a hierarchical structure according to claim 1, characterized in that, The diethyldithiocarbamate is sodium diethyldithiocarbamate and / or potassium diethyldithiocarbamate.

4. The method for preparing iron-based sulfides with a hierarchical structure according to claim 1, characterized in that, The weight-to-volume ratio of the ferric diethyldithiocarbamate to the anhydrous ethylenediamine is 1 g / 30~50 mL.

5. The method for preparing iron-based sulfides with a hierarchical structure according to claim 1, characterized in that, The temperature of the solvothermal reaction is 140~180℃.

6. The iron-based sulfide with a hierarchical structure prepared by the preparation method according to any one of claims 1-5.

7. The application of the iron-based sulfide with a hierarchical structure according to claim 6 in the catalytic reduction of nitroaromatic hydrocarbons.

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