A class of magnetic Fe3O4@SiO2@PNIPAM supported PdCu catalysts, their irradiation preparation method and applications

Abstract

This invention belongs to the field of heterogeneous catalytic hydrogenation technology of chloronitrobenzene, specifically the irradiation preparation and application of a magnetic Fe3O4@SiO2@PNIPAM supported PdCu catalyst. This catalyst is synthesized through gamma-ray irradiation induction, using an organic-inorganic hybrid material of polymer PNIPAM grafted with silica and coated with iron(III) oxide as the catalyst support, and loaded with a palladium-copper active bimetallic catalyst. This catalyst provides milder reaction conditions in the tandem hydrogenation of chloronitrobenzene, achieving complete hydrogenation reduction of chloronitrobenzene at room temperature and pressure. The catalyst exhibits good stability and rapid reaction; the absence of any inorganic or organic additives greatly simplifies the product separation or purification process, avoids the use of high-pressure hydrogen sources, significantly improves production safety, and reduces production costs.

Description

Technical Field

[0001] This invention belongs to the field of heterogeneous catalytic hydrogenation technology of chloronitrobenzene, specifically the irradiation preparation of a magnetic Fe3O4@SiO2@PNIPAM supported PdCu catalyst and its catalytic hydrogenation method for chloronitrobenzene. Background Technology

[0002] Chlorotibene is an important class of organic compounds and industrial intermediates, widely used in human society and industrial development. However, these compounds also cause many environmental hazards; for example, they have strong resistance to biodegradation and can cause serious damage to the central nervous system of animals. Currently, the most effective method for removing chloronitrobenzene is its reduction to the corresponding chloroaniline. Chloroaniline, as an important industrial intermediate in chemical production, is widely used in various production fields such as chemicals and fine chemicals. Therefore, research on the hydrogenation reduction of chloronitrobenzene is of great significance to the ecological environment and industrial production.

[0003] The traditional hydrogenation reduction of chloronitrobenzene utilizes compressed H2 under high temperature and pressure. However, compressed H2 has poor solubility in solution and poses a flammable and explosive hazard. Therefore, in recent years, hydrogen-rich compounds such as sodium borohydride, formic acid, and ammonia borane have been used to replace traditional compressed H2. This allows for in-situ hydrogen production in the liquid phase via a one-pot method, which is then directly applied to the hydrogenation reduction of chloronitrobenzene. This method effectively increases the reaction rate and is simpler and safer. It not only eliminates the need for additional hydrogen gas but also eliminates the risks associated with flammable and explosive hydrogen reduction methods.

[0004] In the hydrogenation reduction of halonitro compounds, halonitrobenzene may undergo dechlorination to form aniline. To solve the dehalogenation phenomenon during the reduction process, the preparation of highly active and selective catalysts has become the primary problem to be solved. Generally, noble metals have higher activity than non-noble metals, and the smaller the particle size and the larger the specific surface area, the greater the activity. However, metal catalysts are easily leached out of the solution during the reaction, and are difficult to separate and recover after the reaction. Therefore, a good support is needed to solve the above problems. Magnetic core-shell structure materials have the characteristics of easy recovery due to their magnetic properties. At the same time, compared with single metal catalysts, in the case of bimetallic or multimetallic catalysts, the metals will produce synergistic effects and have high chemical selectivity (Journal of the American Chemical Society.2008,130(27):8748-8753.). Since single magnetic core-shell structure materials themselves have limitations such as lack of active components, hydrothermal stability and poor reactivity, especially in aqueous solutions, magnetic catalysts are prone to agglomeration, which affects the catalytic effect. Therefore, in order to expand the scope of practical applications, the materials can be modified. Poly(N-isopropylacrylamide) (PNIPAM) is a common temperature-responsive polymer. Its aqueous solution has a minimum critical solution temperature (LCST) of approximately 32°C. From below to above the LCST, the structure of PNIPAM undergoes a reversible transformation from hydrophilic to hydrophobic. Polymerizing monomeric NIPAM on the surface of a magnetic core-shell structure material to synthesize hybrid particles with a shell of PNIPAM significantly improves its dispersibility in aqueous solution and allows for dual recovery based on both temperature and magnetic properties.

[0005] Material modification is typically carried out through chemical methods, which, while significantly improving catalyst activity, involve complex preparation processes. Therefore, external physical methods can be explored to improve metal nanocatalysts. Radiation techniques, utilizing the chemical effects of high-energy rays such as gamma (γ) rays and electron beams, offer several advantages, including environmental friendliness, mild conditions, high reduction efficiency, ease of operation, and large-scale production. Furthermore, γ-rays possess strong penetrating power, allow for large processable thicknesses, and are environmentally friendly, energy-saving, and pollution-free, avoiding the cumbersome processes of conventional methods and overcoming the disadvantage of uneven nucleation during nanoparticle reduction. N. Lingaiah et al. prepared a Cu-Cr-Zn mixed oxide catalyst using gamma-ray radiation, which demonstrated excellent hydrogenation activity when used as a hydrogenation catalyst for the selective hydrogenation of furfural to furfuryl alcohol (Catalysis Letters 2019, 149, 2758-2766). Chinese patent (CN104418756A) uses a prepared supported noble metal catalyst to selectively hydrogenate chloronitrobenzene to produce chloroaniline in a liquid phase system using hydrogen as the hydrogen source. Summary of the Invention

[0006] The first objective of this invention is to address the problems existing in the prior art by improving the preparation method of a magnetic Fe3O4@SiO2@PNIPAM supported PdCu catalyst. In this method, by mixing polymer monomers, palladium salts, and copper salts and adding them to the reaction system, in-situ reduction of the palladium-copper bimetallic compound is achieved simultaneously with polymer grafting, simplifying the catalyst preparation process. Furthermore, it utilizes the advantages of gamma rays—environmentally friendly, mild conditions, high reduction efficiency, ease of operation, and large-scale production—as well as their strong penetrating power and environmentally friendly, energy-saving, and pollution-free characteristics. This avoids the cumbersome processes of conventional methods and overcomes the disadvantage of uneven nucleation during nanoparticle reduction.

[0007] The second objective of this invention is to protect a magnetic Fe3O4@SiO2@PNIPAM supported PdCu catalyst prepared by the above method, which exhibits good stability and rapid reaction.

[0008] The third objective of this invention is to protect the application of a magnetic Fe3O4@SiO2@PNIPAM supported PdCu catalyst prepared by the above method. This catalyst can be used in the method of catalyzing the hydrogenation reduction of chloronitrobenzene. It has very good hydrogenation reduction performance for chloronitrobenzene, so that chloronitrobenzene can be completely reduced to chloroaniline.

[0009] To achieve the above-mentioned objectives, the specific technical solution of this invention is as follows:

[0010] A magnetic Fe3O4@SiO2@PNIPAM-supported PdCu catalyst was synthesized in a one-pot manner induced by gamma ray irradiation. The catalyst support was an organic-inorganic hybrid material with polymer (PNIPAM) grafted silica and magnetic iron oxide coated with magnetic iron oxide, which was used as the catalyst support to support a palladium-copper active bimetallic catalyst.

[0011] Furthermore, to obtain a magnetic Fe3O4@SiO2@PNIPAM-supported PdCu catalyst with better performance, the theoretical loading mass ratio of the active metal Pd to Cu is 1:10. The mass of the active metal Pd is 4 wt% of the mass of the Fe3O4@SiO2@PNIPAM-supported PdCu catalyst.

[0012] The preferred irradiation intensity of the γ-rays used is 5–50 KGy.

[0013] A method for preparing a type of magnetic Fe3O4@SiO2@PNIPAM supported PdCu catalyst includes the following steps:

[0014] 1) Dissolve ferric chloride and ferrous sulfate in water, stir under N2 atmosphere, and add concentrated ammonia dropwise when the temperature rises to a certain temperature. After the solution turns from orange to black, heat it to a certain temperature and stir vigorously for a period of time. After the reaction stops, filter and dry under vacuum to obtain magnetic iron(III) oxide.

[0015] 2) The magnetic iron oxide prepared in 1) was added to a mixed solution of ethanol and water, stirred, and then tetraethyl orthosilicate and ammonia were added. The mixture was stirred and cooled to room temperature. The mixture was then vacuum dried to obtain a dark brown powder. The dark brown powder prepared by the above method, along with a surfactant and concentrated ammonia, was then added to a mixed solution of ethanol and water. Tetraethyl orthosilicate was added while stirring at a certain temperature. The mixture was reacted for a period of time, cooled to room temperature, vacuum dried, and then calcined at high temperature to obtain silica-coated magnetic iron oxide.

[0016] 3) The silica-coated magnetic iron tetroxide prepared in step 2) was added to a toluene solution and stirred. Triethylamine and silane coupling agent KH-570 were added under N2 atmosphere. After heating to a certain temperature and reacting for a period of time, stirring was continued. After cooling to room temperature, the mixture was filtered, washed, and vacuum dried to prepare a precursor of magnetic Fe3O4@SiO2@PNIPAM supported PdCu catalyst.

[0017] 4) Add the precursor and polymer monomer obtained in step 3) to the alcohol solution, stir, then add the alcohol solution containing copper salt and Pd salt, continue stirring, purge with nitrogen gas for half an hour, and then place... 60 The catalyst was irradiated under a Co γ-ray source, centrifuged after irradiation, and then vacuum dried to obtain Fe3O4@SiO2@PNIPAM supported PdCu catalyst.

[0018] Preferably, the silicon source is tetraethyl orthosilicate; the silane coupling agent is silane coupling agent KH-570; the polymer monomer is acrylamide, the palladium salt is palladium chloride, the copper salt is copper sulfate; and the alcohol is ethanol.

[0019] The irradiation source intensity is 5–50 kGy, and the irradiation time is 24–72 h.

[0020] In order to achieve a reasonable ratio between palladium salt and copper salt in the present invention, the preferred mass ratio of palladium element in palladium salt to copper element in copper salt is 1:10.

[0021] In order to make the reaction more complete, it is preferable to stir during the reaction, with a stirring speed of 200 to 800 rpm, and more preferably 300 rpm.

[0022] In step 1), in order to dissolve the iron salt in the water, it needs to be stirred for about 1 hour, and after heating concentrated ammonia water (25wt%), it needs to be reacted at 85℃ for 1 hour.

[0023] After adding the silicon source and concentrated ammonia in step 2), the reaction needs to be carried out for 5 hours.

[0024] After adding the silane coupling agent and triethylamine in step 3), the reaction needs to be carried out at 80°C for 4 hours.

[0025] In step 4), the precursor, polymer monomer, palladium salt, and copper salt need to be stirred in the alcohol for 4 hours.

[0026] The vacuum drying temperature in all steps is 50°C to 70°C, more preferably 60°C, and the drying time is 6 to 12 hours, more preferably 8 hours.

[0027] As a preferred embodiment of this application, step 1) specifically involves: mixing ferric chloride and ferrous sulfate in a certain proportion (Fe... 3+ Fe 2+ =1.0~2.5:1) Dissolve in water, stir under N2 atmosphere, and when the temperature rises to 65℃, add 25wt% concentrated ammonia dropwise. After the solution turns from orange to black, raise the temperature to 85℃ and stir vigorously for a certain period of time (preferably about 1 hour). After the reaction stops, filter and vacuum dry to obtain magnetic iron(III) oxide.

[0028] As a preferred embodiment of this application, step 2) specifically involves: adding the magnetic iron(III) oxide prepared in step 1) to a mixed solution of 125 mL of ethanol and water and stirring, wherein the mixed solution contains 75 wt% ethanol and 25 wt% water; then adding tetraethyl orthosilicate and ammonia solution with a mass fraction of 25 wt%, V 正硅酸乙酯 V 氨水 = 4:1; continue stirring, cool to room temperature, and vacuum dry to obtain a dark brown powder; then mix the dark brown powder prepared by the above method with a surfactant at m 粉末 :m 表面活性剂 =2:1, 25wt% concentrated ammonia solution was added to 150mL of a mixed solution of ethanol and water, which contained 35wt% ethanol and 65wt% water. 4mL of tetraethyl orthosilicate was added while stirring at 80℃, and the reaction was carried out for 2h. After cooling to room temperature, the mixture was vacuum dried for 8h and then calcined at high temperature to obtain silica-coated magnetic iron tetroxide. The surfactant was dodecyltrimethylammonium bromide. The high-temperature calcination temperature was 450-650℃ and the high-temperature calcination time was 3h.

[0029] As a preferred embodiment of this application, the specific steps of step 3) are as follows: the silica-coated magnetic iron tetroxide prepared in step 2) is added to 100 mL of toluene solution, stirred, 1 mL of triethylamine and 2 mL of silane coupling agent KH-570 are added under N2 atmosphere, heated to 80°C and reacted for 4 h with stirring, cooled to room temperature, filtered and washed, and vacuum dried to prepare the precursor of magnetic Fe3O4@SiO2@PNIPAM supported PdCu catalyst.

[0030] As a preferred embodiment of this application, step 4) specifically involves: mixing the precursor obtained in step 3) with the polymer monomer (m 前驱体 :m 聚合物单体 =4:1) Add to 50 mL of alcohol solution, stir for 30 min, then add alcohol solution containing copper salt (35-140 mg / mL, specifically 35 mg / mL, 45 mg / mL, 55 mg / mL, 65 mg / mL, 75 mg / mL, 85 mg / mL, 95 mg / mL, 105 mg / mL, 115 mg / mL, 125 mg / mL, 135 mg / mL, 140 mg / mL, etc.) and alcohol solution containing Pd salt (7 mg / mL), continue stirring, purge with nitrogen gas for half an hour, then place 60 Irradiate the catalyst with a Co γ-ray source for 12–72 h (specifically 12 h, 15 h, 20 h, 25 h, 30 h, 35 h, 40 h, 45 h, 50 h, 55 h, 60 h, 65 h, 70 h, 72 h, etc.), centrifuge after irradiation, and vacuum dry to obtain Fe3O4@SiO2@PNIPAM supported PdCu catalyst.

[0031] Preferably, the polymer monomer is acrylamide; the palladium salt is palladium chloride; the copper salt is copper sulfate; the alcohol is ethanol; and the intensity of the irradiation source is 5–50 kGy (specifically, it can be 5 kGy, 10 kGy, 15 kGy, 20 kGy, 25 kGy, 30 kGy, 35 kGy, 40 kGy, 45 kGy, 50 kGy, etc.).

[0032] In this invention, palladium and copper are mainly added in the form of metal compounds, and then reduced, so that the final product on the catalyst is 0-valent palladium and 0-valent copper.

[0033] The amounts of palladium and copper compounds are determined based on the amount of palladium and copper in the final magnetic Fe3O4@SiO2@PNIPAM supported PdCu catalyst, which is equal to the mass of the catalyst.

[0034] Whether the reduction is complete can be detected by X-ray photoelectron spectroscopy analysis until the loaded metal is at zero valence.

[0035] The method for catalyzing the hydrogenation reduction of chloronitrobenzene using the magnetic Fe3O4@SiO2@PNIPAM supported PdCu catalyst prepared in this invention is carried out according to the following steps:

[0036] The magnetic Fe3O4@SiO2@PNIPAM supported PdCu catalyst, chloronitrobenzene, and ammonia borane prepared in this invention are added to a reaction flask. The mass ratio of the magnetic Fe3O4@SiO2@PNIPAM supported PdCu catalyst to chloronitrobenzene and ammonia borane is 5:78:16-62. Then, a mixed solvent of ethanol and water is added while stirring at a temperature of 25°C. After the reaction is completed, the reaction solution is removed after cooling.

[0037] Further, the chloronitrobenzene is preferably m-chloronitrobenzene, o-chloronitrobenzene, or p-chloronitrobenzene; the mass of the magnetic Fe3O4@SiO2@PNIPAM supported PdCu catalyst is preferably 1-30 mg (specifically, it can be 1 mg, 2 mg, 3 mg, 4 mg, 5 mg, 6 mg, 7 mg, 8 mg, 9 mg, 10 mg, 11 mg, 12 mg, 13 mg, 14 mg, 15 mg, 16 mg, 17 mg, 18 mg, 19 mg, 20 mg, 21 mg, 22 mg, 23 mg, 24 mg, 25 mg, 26 mg, 27 mg, 28 mg, 29 mg, 30 mg, etc.).

[0038] Furthermore, it is preferable that the amount of ethanol added in the mixed solvent is 20% to 100%.

[0039] Further, it is preferred that the introduced ammonia borane is 16-62 mg (16 mg, 20 mg, 25 mg, 30 mg, 35 mg, 40 mg, 45 mg, 50 mg, 55 mg, 60 mg, 62 mg, etc.); the stirring speed is preferably 300-1300 rpm; and the reaction time for the hydrogenation reduction of chloronitrobenzene is 2-60 min (2 min, 5 min, 10 min, 15 min, 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, 60 min, etc.).

[0040] Compared with the prior art, the positive effects of the present invention are reflected in:

[0041] (I) A Fe3O4@SiO2@PNIPAM-supported PdCu catalyst was prepared using gamma-ray induction. In the preparation process, the polymer monomer, palladium salt, and copper salt were mixed and added to the reaction system, achieving in-situ reduction of the palladium-copper bimetallic compound while simultaneously grafting the polymer, simplifying the catalyst preparation process. Furthermore, the advantages of gamma rays—environmentally friendly, mild conditions, high reduction efficiency, ease of operation, large-scale production, strong penetrating power, and environmentally friendly, energy-saving, and pollution-free—were utilized. This avoids the cumbersome processes of conventional methods and overcomes the disadvantage of uneven nucleation during nanoparticle reduction. This type of catalyst exhibits excellent hydrogenation reduction performance for chloronitrobenzene, enabling the complete reduction of chloronitrobenzene to chloroaniline.

[0042] (ii) The reaction conditions are milder, achieving complete reduction of chloronitrobenzene at room temperature and pressure. The catalyst exhibits good stability and the reaction is rapid. For example, the reaction time reported in the literature is generally 1 hour, while the catalyst prepared using the method of this invention can achieve a reaction time as fast as 5 minutes.

[0043] (III) The hydrogenation reduction system of chloronitrobenzene in this invention does not require any inorganic or organic additives or additional hydrogen sources, which greatly simplifies the separation or purification process of the product and reduces production costs.

[0044] (iv) The hydrogenation reduction system of chloronitrobenzene in this invention can be carried out in a green chemical solvent, which greatly reduces environmental pollution and is more in line with the concept of green chemistry. Attached Figure Description

[0045] Figure 1 This is a schematic diagram of the irradiation-assisted preparation of a magnetic organic-inorganic hybrid nano-Fe3O4@SiO2@PNIPAM supported PdCu catalyst.

[0046] Figure 2 A schematic diagram of in-situ hydrogenation of chloronitrobenzene catalyzed by a PdCu catalyst supported on magnetic organic-inorganic hybrid nano-Fe3O4@SiO2@PNIPAM. Detailed Implementation

[0047] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, unless otherwise specified, the following embodiments and features can be combined with each other. Operations not described in detail in this application are conventional operations in the art or do not have a specific impact on the effect of this application.

[0048] In the following examples, the polymer monomers are all acrylamide, the palladium salt is palladium chloride, the copper salt is copper sulfate, the alcohol is ethanol, the surfactant is dodecyltrimethylammonium bromide, and the silane coupling agent is KH-570. In this application, the mass fraction of concentrated ammonia is 25%.

[0049] Example 1:

[0050] Preparation of magnetic Fe3O4@SiO2@PNIPAM supported PdCu catalyst and method for catalyzing the reduction of m-chloronitrobenzene using this catalyst:

[0051] First, 4.73 g of ferric chloride and 2.78 g of ferrous sulfate were dissolved in 100 mL of water. Then, 30 mL of concentrated ammonia (mass fraction: 25%) was added to the solution at 65 °C. After the solution turned from orange to black, the temperature was raised to 85 °C and stirred vigorously for 1 h. After the reaction stopped, the solution was filtered and dried under vacuum at 60 °C for 8 h to obtain magnetic iron(III) oxide.

[0052] Next, 2g of magnetic Fe3O4 was added to 100mL of anhydrous ethanol and 25mL of water, and sonicated for 30min. Then, 6mL of tetraethyl orthosilicate (TEOS) and 24mL of ammonia were added, and the mixture was mechanically stirred at 40℃ for 5h. After stirring, the mixture was cooled to room temperature and dried under vacuum at 60℃ for 8h. 2g of the dried powder and 1g of hexadecylammonium bromide were added to a 250mL three-necked flask. 50mL of ethanol, 100mL of water, and 12mL of ammonia were added to the flask, and the mixture was stirred until the temperature reached 80℃. Then, 4mL of TEOS was added, and the reaction was continued for 2h. The mixture was then poured into a beaker and sonicated for 30min. After washing three times with alternating ethanol and water, the mixture was dried under vacuum at 60℃ for 8h. The resulting sample was then calcined in a muffle furnace at 650℃ for 3h and ground to obtain magnetic Fe3O4@SiO2.

[0053] 2g of silica-coated magnetic iron tetroxide was added to 100mL of toluene solution and stirred. Then, 1mL of triethylamine and 2mL of silane coupling agent were added. The mixture was heated to 80℃ and reacted for 4h. After cooling to room temperature, the mixture was filtered, washed, and dried under vacuum at 60℃ for 8h to prepare a precursor for a magnetic Fe3O4@SiO2@PNIPAM-supported PdCu catalyst.

[0054] Finally, 1g of precursor, 250mg of polymer monomer, 70mg of palladium salt, and 700mg of copper salt were added to the alcohol and stirred for 4 hours. Nitrogen gas was then bubbled through the mixture for half an hour, and the mixture was placed in a container. 60 Irradiated with a Co γ-ray source for 48 h at an absorbed dose of 25 kGy. After irradiation, the catalyst was centrifuged and dried under vacuum at 60 °C for 8 h to obtain the magnetic Fe3O4@SiO2@PNIPAM supported PdCu catalyst of this invention.

[0055] 5.0 mg of magnetic Fe3O4@SiO2@PNIPAM supported PdCu catalyst, 78 mg of m-chloronitrobenzene, and 46 mg of ammonia borane were added to a 25 mL two-necked round-bottom flask. Then, 5 mL of a mixed solvent (60 w% ethanol, 40 w% water) was added while stirring at 20 rar / s. After reacting for 5 min, the mixture was filtered through a funnel, and the filtrate was subjected to gas phase analysis. The conversion rate of m-chloronitrobenzene was 100%, and the yield of m-chloroaniline was 100%.

[0056] Example 2:

[0057] Preparation of magnetic Fe3O4@SiO2@PNIPAM supported PdCu catalyst and method for catalyzing the reduction of m-chloronitrobenzene using this catalyst:

[0058] 4.73 g of ferric chloride and 2.78 g of ferrous sulfate were dissolved in 100 mL of water. Then, 30 mL of concentrated ammonia (mass fraction: 25%) was added to the solution at 65 °C. After the solution turned from orange to black, the temperature was raised to 85 °C and stirred vigorously for 1 h. After the reaction stopped, the solution was filtered and dried under vacuum at 60 °C for 8 h to obtain magnetic iron(III) oxide.

[0059] 2g of magnetic Fe3O4 was added to 100mL of anhydrous ethanol and 25mL of water, and sonicated for 30min. Then, 6mL of tetraethyl orthosilicate (TEOS) and 24mL of ammonia were added, and the mixture was mechanically stirred at 40℃ for 5h. Stirring continued, and the mixture was cooled to room temperature and dried under vacuum at 60℃ for 8h. 2g of the dried powder and 1g of hexadecylammonium bromide were added to a 250mL three-necked flask. 50mL of ethanol, 100mL of water, and 12mL of ammonia were added to the flask, and the mixture was stirred until the temperature reached 80℃. Then, 4mL of TEOS was added, and the reaction continued for 2h. The mixture was then poured into a beaker and sonicated for 30min. After washing three times alternately with ethanol and water, the mixture was dried under vacuum at 60℃ for 8h. The resulting sample was then calcined in a muffle furnace at 650℃ for 3h and ground to obtain magnetic Fe3O4@SiO2.

[0060] 2g of silica-coated magnetic iron tetroxide was added to 100mL of toluene solution and stirred. Then, 1mL of triethylamine and 2mL of silane coupling agent were added. The mixture was heated to 80℃ and reacted for 4h. After cooling to room temperature, the mixture was filtered, washed, and dried under vacuum at 60℃ for 8h to prepare a precursor for a magnetic Fe3O4@SiO2@PNIPAM-supported PdCu catalyst.

[0061] Finally, 1g of precursor, 250mg of polymer monomer, 70mg of palladium salt, and 700mg of copper salt were added to the alcohol and stirred for 4 hours. Nitrogen gas was then bubbled through the mixture for half an hour, and the mixture was placed in a container. 60Irradiated with a Co γ-ray source for 48 h at an absorbed dose of 25 kGy. After irradiation, the catalyst was centrifuged and dried under vacuum at 60 °C for 8 h to obtain the magnetic Fe3O4@SiO2@PNIPAM supported PdCu catalyst of this invention.

[0062] 5.0 mg of magnetic Fe3O4@SiO2@PNIPAM supported PdCu catalyst, 78 mg of m-chloronitrobenzene, and 62 mg of ammonia borane were added to a 25 mL two-necked round-bottom flask. Then, 5 mL of a mixed solvent (60 w% ethanol, 40 w% water) was added while stirring at 20 rar / s. After reacting for 5 min, the mixture was filtered through a funnel, and the filtrate was subjected to gas phase analysis. The conversion rate of m-chloronitrobenzene was 100%, and the yield of m-chloroaniline was 99.53%.

[0063] Example 3:

[0064] Preparation of magnetic Fe3O4@SiO2@PNIPAM supported PdCu catalyst and method for catalyzing the reduction of m-chloronitrobenzene using this catalyst:

[0065] First, 4.73 g of ferric chloride and 2.78 g of ferrous sulfate were dissolved in 100 mL of water. Then, 30 mL of concentrated ammonia (mass fraction: 25%) was added to the solution at 65 °C. After the solution turned from orange to black, the temperature was raised to 85 °C and stirred vigorously for 1 h. After the reaction stopped, the solution was filtered and dried under vacuum at 60 °C for 8 h to obtain magnetic iron(III) oxide.

[0066] Next, 2g of magnetic Fe3O4 was added to 100mL of anhydrous ethanol and 25mL of water, and sonicated for 30min. Then, 6mL of tetraethyl orthosilicate (TEOS) and 24mL of ammonia were added, and the mixture was mechanically stirred at 40℃ for 5h. After stirring, the mixture was cooled to room temperature and dried under vacuum at 60℃ for 8h. 2g of the dried powder and 1g of hexadecylammonium bromide were added to a 250mL three-necked flask. 50mL of ethanol, 100mL of water, and 12mL of ammonia were added to the flask, and the mixture was stirred until the temperature reached 80℃. Then, 4mL of TEOS was added, and the reaction was continued for 2h. The mixture was then poured into a beaker and sonicated for 30min. After washing three times with alternating ethanol and water, the mixture was dried under vacuum at 60℃ for 8h. The resulting sample was then calcined in a muffle furnace at 650℃ for 3h and ground to obtain magnetic Fe3O4@SiO2.

[0067] 2g of silica-coated magnetic iron tetroxide was added to 100mL of toluene solution and stirred. Then, 1mL of triethylamine and 2mL of silane coupling agent were added. The mixture was heated to 80℃ and reacted for 4h. After cooling to room temperature, the mixture was filtered, washed, and dried under vacuum at 60℃ for 8h to prepare a precursor for a magnetic Fe3O4@SiO2@PNIPAM-supported PdCu catalyst.

[0068] Finally, 1g of precursor, 250mg of polymer monomer, 70mg of palladium salt, and 700mg of copper salt were added to the alcohol and stirred for 4 hours. Nitrogen gas was then bubbled through the mixture for half an hour, and the mixture was placed in a container. 60 Irradiated for 24 hours with a Co γ-ray irradiation source and an absorbed irradiation dose of 15 kGy. After irradiation, the catalyst was centrifuged and dried under vacuum at 60°C for 8 hours to obtain the magnetic Fe3O4@SiO2@PNIPAM supported PdCu catalyst of this invention.

[0069] 5.0 mg of magnetic Fe3O4@SiO2@PNIPAM supported PdCu catalyst, 78 mg of m-chloronitrobenzene, and 46 mg of ammonia borane were added to a 25 mL two-necked round-bottom flask. Then, 5 mL of a mixed solvent (60 w% ethanol, 40 w% water) was added while stirring at 20 rar / s. After reacting for 10 min, the mixture was filtered through a funnel, and the filtrate was subjected to gas phase analysis. The conversion rate of m-chloronitrobenzene was 100%, and the yield of m-chloroaniline was 99.30%.

[0070] Example 4:

[0071] Preparation of magnetic Fe3O4@SiO2@PNIPAM supported PdCu catalyst and method for catalyzing the reduction of m-chloronitrobenzene using this catalyst:

[0072] First, 4.73 g of ferric chloride and 2.78 g of ferrous sulfate were dissolved in 100 mL of water. Then, 30 mL of concentrated ammonia (mass fraction: 25%) was added to the solution at 65 °C. After the solution turned from orange to black, the temperature was raised to 85 °C and stirred vigorously for 1 h. After the reaction stopped, the solution was filtered and dried under vacuum at 60 °C for 8 h to obtain magnetic iron(III) oxide.

[0073] Next, 2g of magnetic Fe3O4 was added to 100mL of anhydrous ethanol and 25mL of water, and sonicated for 30min. Then, 6mL of tetraethyl orthosilicate (TEOS) and 24mL of ammonia were added, and the mixture was mechanically stirred at 40℃ for 5h. After stirring, the mixture was cooled to room temperature and dried under vacuum at 60℃ for 8h. 2g of the dried powder and 1g of hexadecylammonium bromide were added to a 250mL three-necked flask. 50mL of ethanol, 100mL of water, and 12mL of ammonia were added to the flask, and the mixture was stirred until the temperature reached 80℃. Then, 4mL of TEOS was added, and the reaction was continued for 2h. The mixture was then poured into a beaker and sonicated for 30min. After washing three times with alternating ethanol and water, the mixture was dried under vacuum at 60℃ for 8h. The resulting sample was then calcined in a muffle furnace at 650℃ for 3h and ground to obtain magnetic Fe3O4@SiO2.

[0074] 2g of silica-coated magnetic iron tetroxide was added to 100mL of toluene solution and stirred. Then, 1mL of triethylamine and 2mL of silane coupling agent were added. The mixture was heated to 80℃ and reacted for 4h. After cooling to room temperature, the mixture was filtered, washed, and dried under vacuum at 60℃ for 8h to prepare a precursor for a magnetic Fe3O4@SiO2@PNIPAM-supported PdCu catalyst.

[0075] Finally, 1g of precursor, 250mg of polymer monomer, 70mg of palladium salt, and 700mg of copper salt were added to the alcohol and stirred for 4 hours. Nitrogen gas was then bubbled through the mixture for half an hour, and the mixture was placed in a container. 60 Irradiated for 12 hours with a Co γ-ray source at an absorbed dose of 5 kGy. After irradiation, the product was centrifuged and dried under vacuum at 60°C for 8 hours to obtain the magnetic Fe3O4@SiO2@PNIPAM supported PdCu catalyst of this invention.

[0076] 20.0 mg of magnetic Fe3O4@SiO2@PNIPAM supported PdCu catalyst, 78 mg of m-chloronitrobenzene, and 46 mg of ammonia borane were added to a 25 mL two-necked round-bottom flask. Then, 5 mL of a mixed solvent (40 w% ethanol, 60 w% water) was added while stirring at 20 rar / s. After reacting for 10 min, the mixture was filtered through a funnel, and the filtrate was analyzed by gas chromatography. The conversion rate of m-chloronitrobenzene was 100%, and the yield of m-chloroaniline was 97.82%.

[0077] Example 5:

[0078] Preparation of magnetic Fe3O4@SiO2@PNIPAM supported PdCu catalyst and method for catalyzing the reduction of m-chloronitrobenzene using this catalyst:

[0079] First, 4.73 g of ferric chloride and 2.78 g of ferrous sulfate were dissolved in 100 mL of water. Then, 30 mL of concentrated ammonia (mass fraction: 25%) was added to the solution at 65 °C. After the solution turned from orange to black, the temperature was raised to 85 °C and stirred vigorously for 1 h. After the reaction stopped, the solution was filtered and dried under vacuum at 60 °C for 8 h to obtain magnetic iron(III) oxide.

[0080] Next, 2g of magnetic Fe3O4 was added to 100mL of anhydrous ethanol and 25mL of water, and sonicated for 30min. Then, 6mL of tetraethyl orthosilicate (TEOS) and 24mL of ammonia were added, and the mixture was mechanically stirred at 40℃ for 5h. After stirring, the mixture was cooled to room temperature and dried under vacuum at 60℃ for 8h. 2g of the dried powder and 1g of hexadecylammonium bromide were added to a 250mL three-necked flask. 50mL of ethanol, 100mL of water, and 12mL of ammonia were added to the flask, and the mixture was stirred until the temperature reached 80℃. Then, 4mL of TEOS was added, and the reaction was continued for 2h. The mixture was then poured into a beaker and sonicated for 30min. After washing three times with alternating ethanol and water, the mixture was dried under vacuum at 60℃ for 8h. The resulting sample was then calcined in a muffle furnace at 650℃ for 3h and ground to obtain magnetic Fe3O4@SiO2.

[0081] 2g of silica-coated magnetic iron tetroxide was added to 100mL of toluene solution and stirred. Then, 1mL of triethylamine and 2mL of silane coupling agent were added. The mixture was heated to 80℃ and reacted for 4h. After cooling to room temperature, the mixture was filtered, washed, and dried under vacuum at 60℃ for 8h to prepare a precursor for a magnetic Fe3O4@SiO2@PNIPAM-supported PdCu catalyst.

[0082] Finally, 1g of precursor, 250mg of polymer monomer, 70mg of palladium salt, and 700mg of copper salt were added to the alcohol and stirred for 4 hours. Nitrogen gas was then bubbled through the mixture for half an hour, and the mixture was placed in a container. 60 Irradiated for 72 hours with a Co γ-ray irradiation source and an absorbed dose of 50 kGy, the catalyst was centrifuged after irradiation and dried under vacuum at 60°C for 8 hours to obtain the magnetic Fe3O4@SiO2@PNIPAM supported PdCu catalyst of this invention.

[0083] 5.0 mg of magnetic Fe3O4@SiO2@PNIPAM supported PdCu catalyst, 78 mg of m-chloronitrobenzene, and 46 mg of ammonia borane were added to a 25 mL two-necked round-bottom flask. Then, 5 mL of a mixed solvent (60 w% ethanol, 40 w% water) was added while stirring at 20 rar / s. After reacting for 5 min, the mixture was filtered through a funnel, and the filtrate was subjected to gas phase analysis. The conversion rate of m-chloronitrobenzene was 96.93%, and the yield of m-chloroaniline was 96.48%.

[0084] Example 6:

[0085] Preparation of magnetic Fe3O4@SiO2@PNIPAM supported PdCu catalyst and method for catalyzing the reduction of m-chloronitrobenzene using this catalyst:

[0086] First, 4.73 g of ferric chloride and 2.78 g of ferrous sulfate were dissolved in 100 mL of water. Then, 30 mL of concentrated ammonia (mass fraction: 25%) was added to the solution at 65 °C. After the solution turned from orange to black, the temperature was raised to 85 °C and stirred vigorously for 1 h. After the reaction stopped, the solution was filtered and dried under vacuum at 60 °C for 8 h to obtain magnetic iron(III) oxide.

[0087] Next, 2g of magnetic Fe3O4 was added to 100mL of anhydrous ethanol and 25mL of water, and sonicated for 30min. Then, 6mL of tetraethyl orthosilicate (TEOS) and 24mL of ammonia were added, and the mixture was mechanically stirred at 40℃ for 5h. After stirring, the mixture was cooled to room temperature and dried under vacuum at 60℃ for 8h. 2g of the dried powder and 1g of hexadecylammonium bromide were added to a 250mL three-necked flask. 50mL of ethanol, 100mL of water, and 12mL of ammonia were added to the flask, and the mixture was stirred until the temperature reached 80℃. Then, 4mL of TEOS was added, and the reaction was continued for 2h. The mixture was then poured into a beaker and sonicated for 30min. After washing three times with alternating ethanol and water, the mixture was dried under vacuum at 60℃ for 8h. The resulting sample was then calcined in a muffle furnace at 650℃ for 3h and ground to obtain magnetic Fe3O4@SiO2.

[0088] 2g of silica-coated magnetic iron tetroxide was added to 100mL of toluene solution and stirred. Then, 1mL of triethylamine and 2mL of silane coupling agent were added. The mixture was heated to 80℃ and reacted for 4h. After cooling to room temperature, the mixture was filtered, washed, and dried under vacuum at 60℃ for 8h to prepare a precursor for a magnetic Fe3O4@SiO2@PNIPAM-supported PdCu catalyst.

[0089] Finally, 1g of precursor, 250mg of polymer monomer, 70mg of palladium salt, and 700mg of copper salt were added to the alcohol and stirred for 4 hours. Nitrogen gas was then bubbled through the mixture for half an hour, and the mixture was placed in a container. 60 Irradiated with a Co γ-ray source for 48 h at an absorbed dose of 25 kGy, followed by centrifugation and vacuum drying at 60 °C for 8 h after irradiation to obtain the magnetic Fe3O4@SiO2@PNIPAM supported PdCu catalyst of this invention.

[0090] 5.0 mg of magnetic Fe3O4@SiO2@PNIPAM supported PdCu catalyst, 78 mg of m-chloronitrobenzene, and 46 mg of ammonia borane were added to a 25 mL two-necked round-bottom flask. Then, 5 mL of a mixed solvent (60 w% ethanol, 40 w% water) was added while stirring at 20 rar / s. After reacting for 20 min, the mixture was filtered through a funnel, and the filtrate was analyzed by gas chromatography. The conversion of m-chloronitrobenzene was 100%, and the yield of m-chloroaniline was 99.53%.

[0091] Example 7:

[0092] Preparation of magnetic Fe3O4@SiO2@PNIPAM supported PdCu catalyst and method for catalyzing the reduction of m-chloronitrobenzene using this catalyst:

[0093] First, 4.73 g of ferric chloride and 2.78 g of ferrous sulfate were dissolved in 100 mL of water. Then, 30 mL of concentrated ammonia (mass fraction: 25%) was added to the solution at 65 °C. After the solution turned from orange to black, the temperature was raised to 85 °C and stirred vigorously for 1 h. After the reaction stopped, the solution was filtered and dried under vacuum at 60 °C for 8 h to obtain magnetic iron(III) oxide.

[0094] Next, 2g of magnetic Fe3O4 was added to 100mL of anhydrous ethanol and 25mL of water, and sonicated for 30min. Then, 6mL of tetraethyl orthosilicate (TEOS) and 24mL of ammonia were added, and the mixture was mechanically stirred at 40℃ for 5h. After stirring, the mixture was cooled to room temperature and dried under vacuum at 60℃ for 8h. 2g of the dried powder and 1g of hexadecylammonium bromide were added to a 250mL three-necked flask. 50mL of ethanol, 100mL of water, and 12mL of ammonia were added to the flask, and the mixture was stirred until the temperature reached 80℃. Then, 4mL of TEOS was added, and the reaction was continued for 2h. The mixture was then poured into a beaker and sonicated for 30min. After washing three times with alternating ethanol and water, the mixture was dried under vacuum at 60℃ for 8h. The resulting sample was then calcined in a muffle furnace at 650℃ for 3h and ground to obtain magnetic Fe3O4@SiO2.

[0095] 2g of silica-coated magnetic iron tetroxide was added to 100mL of toluene solution and stirred. Then, 1mL of triethylamine and 2mL of silane coupling agent were added. The mixture was heated to 80℃ and reacted for 4h. After cooling to room temperature, the mixture was filtered, washed, and dried under vacuum at 60℃ for 8h to prepare a precursor for a magnetic Fe3O4@SiO2@PNIPAM-supported PdCu catalyst.

[0096] Finally, 1g of precursor, 250mg of polymer monomer, 70mg of palladium salt, and 700mg of copper salt were added to the alcohol and stirred for 4 hours. Nitrogen gas was then bubbled through the mixture for half an hour, and the mixture was placed in a container. 60 Irradiated with a Co γ-ray source for 48 h at an absorbed dose of 25 kGy. After irradiation, the catalyst was centrifuged and dried under vacuum at 60 °C for 8 h to obtain the magnetic Fe3O4@SiO2@PNIPAM supported PdCu catalyst of this invention.

[0097] 10.0 mg of magnetic Fe3O4@SiO2@PNIPAM supported PdCu catalyst, 78 mg of m-chloronitrobenzene, and 46 mg of ammonia borane were added to a 25 mL two-necked round-bottom flask. Then, 5 mL of a mixed solvent (60 w% ethanol, 40 w% water) was added while stirring at 20 rar / s. After reacting for 5 min, the mixture was filtered through a funnel, and the filtrate was subjected to gas phase analysis. The conversion rate of m-chloronitrobenzene was 100%, and the yield of m-chloroaniline was 100%.

[0098] Example 8:

[0099] Preparation of magnetic Fe3O4@SiO2@PNIPAM supported PdCu catalyst and method for catalytic reduction of p-chloronitrobenzene using this catalyst:

[0100] 4.73 g of ferric chloride and 2.78 g of ferrous sulfate were dissolved in 100 mL of water. Then, 30 mL of concentrated ammonia (mass fraction: 25%) was added to the solution at 65 °C. After the solution turned from orange to black, the temperature was raised to 85 °C and stirred vigorously for 1 h. After the reaction stopped, the solution was filtered and dried under vacuum at 60 °C for 8 h to obtain magnetic iron(III) oxide.

[0101] 2g of magnetic Fe3O4 was added to 100mL of anhydrous ethanol and 25mL of water, and sonicated for 30min. Then, 6mL of tetraethyl orthosilicate (TEOS) and 24mL of ammonia were added, and the mixture was mechanically stirred at 40℃ for 5h. Stirring continued, and the mixture was cooled to room temperature and dried under vacuum at 60℃ for 8h. 2g of the dried powder and 1g of hexadecylammonium bromide were added to a 250mL three-necked flask. 50mL of ethanol, 100mL of water, and 12mL of ammonia were added to the flask, and the mixture was stirred until the temperature reached 80℃. Then, 4mL of TEOS was added, and the reaction continued for 2h. The mixture was then poured into a beaker and sonicated for 30min. After washing three times alternately with ethanol and water, the mixture was dried under vacuum at 60℃ for 8h. The resulting sample was then calcined in a muffle furnace at 650℃ for 3h and ground to obtain magnetic Fe3O4@SiO2.

[0102] 2g of silica-coated magnetic iron tetroxide was added to 100mL of toluene solution and stirred. Then, 1mL of triethylamine and 2mL of silane coupling agent were added. The mixture was heated to 80℃ and reacted for 4h. After cooling to room temperature, the mixture was filtered, washed, and dried under vacuum at 60℃ for 8h to prepare a precursor for a magnetic Fe3O4@SiO2@PNIPAM-supported PdCu catalyst.

[0103] Finally, 1g of precursor, 250mg of polymer monomer, 70mg of palladium salt, and 700mg of copper salt were added to the alcohol and stirred for 4 hours. Nitrogen gas was then bubbled through the mixture for half an hour, and the mixture was placed in a container. 60 Irradiated with a Co γ-ray source for 48 h at an absorbed dose of 25 kGy. After irradiation, the catalyst was centrifuged and dried under vacuum at 60 °C for 8 h to obtain the magnetic Fe3O4@SiO2@PNIPAM supported PdCu catalyst of this invention.

[0104] 5.0 mg of magnetic Fe3O4@SiO2@PNIPAM supported PdCu catalyst, 78 mg of p-chloronitrobenzene, and 46 mg of ammonia borane were added to a 25 mL two-necked round-bottom flask. Then, 5 mL of a mixed solvent (60 w% ethanol, 40 w% water) was added while stirring at 20 rar / s. After reacting for 5 min, the mixture was filtered through a funnel, and the filtrate was subjected to gas phase analysis. The conversion rate of o-chloronitrobenzene was 99.18%, and the yield of o-chloroaniline was 97.53%.

[0105] Example 9:

[0106] Preparation of magnetic Fe3O4@SiO2@PNIPAM supported PdCu catalyst and method for catalytic reduction of o-chloronitrobenzene using this catalyst:

[0107] 4.73 g of ferric chloride and 2.78 g of ferrous sulfate were dissolved in 100 mL of water. Then, 30 mL of concentrated ammonia (mass fraction: 25%) was added to the solution at 65 °C. After the solution turned from orange to black, the temperature was raised to 85 °C and stirred vigorously for 1 h. After the reaction stopped, the solution was filtered and dried under vacuum at 60 °C for 8 h to obtain magnetic iron(III) oxide.

[0108] 2g of magnetic Fe3O4 was added to 100mL of anhydrous ethanol and 25mL of water, and sonicated for 30min. Then, 6mL of tetraethyl orthosilicate (TEOS) and 24mL of ammonia were added, and the mixture was mechanically stirred at 40℃ for 5h. Stirring continued, and the mixture was cooled to room temperature and dried under vacuum at 60℃ for 8h. 2g of the dried powder and 1g of hexadecylammonium bromide were added to a 250mL three-necked flask. 50mL of ethanol, 100mL of water, and 12mL of ammonia were added to the flask, and the mixture was stirred until the temperature reached 80℃. Then, 4mL of TEOS was added, and the reaction continued for 2h. The mixture was then poured into a beaker and sonicated for 30min. After washing three times alternately with ethanol and water, the mixture was dried under vacuum at 60℃ for 8h. The resulting sample was then calcined in a muffle furnace at 650℃ for 3h and ground to obtain magnetic Fe3O4@SiO2.

[0109] 2g of silica-coated magnetic iron tetroxide was added to 100mL of toluene solution and stirred. Then, 1mL of triethylamine and 2mL of silane coupling agent were added. The mixture was heated to 80℃ and reacted for 4h. After cooling to room temperature, the mixture was filtered, washed, and dried under vacuum at 60℃ for 8h to prepare a precursor for a magnetic Fe3O4@SiO2@PNIPAM-supported PdCu catalyst.

[0110] Finally, 1g of precursor, 250mg of polymer monomer, 70mg of palladium salt, and 700mg of copper salt were added to the alcohol and stirred for 4 hours. Nitrogen gas was then bubbled through the mixture for half an hour, and the mixture was placed in a container. 60Irradiated with a Co γ-ray source for 48 h at an absorbed dose of 25 kGy. After irradiation, the catalyst was centrifuged and dried under vacuum at 60 °C for 8 h to obtain the magnetic Fe3O4@SiO2@PNIPAM supported PdCu catalyst of this invention.

[0111] 5.0 mg of magnetic Fe3O4@SiO2@PNIPAM supported PdCu catalyst, 78 mg of o-chloronitrobenzene, and 46 mg of ammonia borane were added to a 25 mL two-necked round-bottom flask. Then, 5 mL of a mixed solvent (60 w% ethanol, 40 w% water) was added while stirring at 20 rar / s. After reacting for 5 min, the mixture was filtered through a funnel, and the filtrate was subjected to gas phase analysis. The conversion rate of o-chloronitrobenzene was 79.90%, and the yield of o-chloroaniline was 78.63%.

[0112] The foregoing basic examples and their further alternative examples of the present invention can be freely combined to form multiple embodiments, all of which are embodiments that can be adopted and are claimed by the present invention. In the present invention, each alternative example can be arbitrarily combined with any other basic example and alternative example. Those skilled in the art will recognize numerous combinations.

[0113] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a type of magnetic Fe3O4@SiO2@PNIPAM supported PdCu catalyst, characterized in that... This catalyst was synthesized via gamma-ray irradiation induction, using an organic-inorganic hybrid material of polymer PNIPAM grafted with silica and coated with iron oxide as the catalyst support, and loaded with palladium-copper active bimetals; the specific steps include the following: 1) Dissolve ferric chloride and ferrous sulfate in water, stir under N2 atmosphere, and add concentrated ammonia dropwise when the temperature rises to a certain temperature. After the solution turns from orange to black, heat it to a certain temperature and stir vigorously for a period of time. After the reaction stops, filter and vacuum dry to obtain magnetic iron(III) oxide. 2) The magnetic iron oxide prepared in 1) was added to a mixed solution of ethanol and water, stirred, and then tetraethyl orthosilicate and ammonia were added. The mixture was stirred and cooled to room temperature. The mixture was then vacuum dried to obtain a dark brown powder. The dark brown powder prepared by the above method, along with a surfactant and concentrated ammonia, was then added to a mixed solution of ethanol and water. A silicon source was added and stirred at a certain temperature. The mixture was reacted for a period of time, cooled to room temperature, vacuum dried, and then calcined at high temperature to obtain silicon dioxide-coated magnetic iron oxide. 3) The silica-coated magnetic iron tetroxide prepared in step 2) was added to a toluene solution and stirred. Triethylamine and silane coupling agent KH-570 were added under N2 atmosphere. After heating to a certain temperature and reacting for a period of time, stirring was continued. After cooling to room temperature, the mixture was filtered, washed, and vacuum dried to prepare a precursor of magnetic Fe3O4@SiO2@PNIPAM supported PdCu catalyst. 4) Add the precursor and polymer monomer obtained in step 3) to the alcohol solution, stir, then add the alcohol solution containing copper salt and Pd salt, continue stirring, purge with nitrogen gas for half an hour, and then place it in a container. 60 The catalyst was irradiated under a Co γ-ray source, centrifuged after irradiation, and then vacuum dried to obtain Fe3O4@SiO2@PNIPAM supported PdCu catalyst.

2. The preparation method according to claim 1, characterized in that... Step 1) involves the following steps: ferric chloride and ferrous sulfate are mixed according to Fe... 3+ Fe 2+ The solution was dissolved in water at a ratio of 1.0 to 2.5:1 and stirred under a nitrogen atmosphere. When the temperature reached 65 °C, concentrated ammonia was added dropwise. After the solution turned from orange to black, the temperature was raised to 85 °C and stirred vigorously for a certain period of time. After the reaction stopped, the solution was filtered and dried under vacuum to obtain magnetic iron(III) oxide.

3. The preparation method according to claim 1, characterized in that, In step 2), the silicon source is tetraethyl orthosilicate. Specifically, this step involves adding the magnetic iron(III) oxide prepared in step 1) to a mixed solution of ethanol and water and stirring. Then, tetraethyl orthosilicate and concentrated ammonia are added. 正硅酸乙酯 V 氨水 = 4:1; continue stirring, cool to room temperature, and vacuum dry to obtain a dark brown powder; then mix the dark brown powder prepared by the above method with a surfactant at m 粉末 :m 表面活性剂 =2:1, concentrated ammonia water is added to a mixed solution of 35 wt% ethanol and 65 wt% water, and 4 mL of tetraethyl orthosilicate is added while stirring at 80 °C. The reaction is carried out for at least 2 h. After cooling to room temperature, the mixture is vacuum dried for 8 h to 10 h and then calcined at high temperature to obtain silica-coated magnetic iron tetroxide. The surfactant is dodecyltrimethylammonium bromide. The high-temperature calcination temperature is 450–650 °C and the high-temperature calcination time is 3–5 h.

4. The preparation method according to claim 1, characterized in that, The specific steps of step 3) are as follows: the silica-coated magnetic iron tetroxide prepared in step 2) is added to 100 mL of toluene solution, stirred, and 1 mL of triethylamine and 2 mL of silane coupling agent KH-570 are added under N2 atmosphere. After heating to 80 ℃, the reaction is continued for 4 h with stirring. After cooling to room temperature, the mixture is filtered, washed, and vacuum dried to prepare the precursor of magnetic Fe3O4@SiO2@PNIPAM supported PdCu catalyst.

5. The preparation method according to claim 1, characterized in that, Step 4 involves adding the precursor and polymer monomer obtained in step 3) to 50 mL of an alcohol solution. 前驱体 :m 聚合物单体 =4:1; After stirring for 30 min, add an alcohol solution containing 35-140 mg / mL copper salt and 7 mg / mL Pd salt, continue stirring, purge with nitrogen gas for half an hour, and then place... 60 Irradiated for 12–72 h under a Co γ-ray irradiation source, followed by centrifugation and vacuum drying to obtain a Fe3O4@SiO2@PNIPAM supported PdCu catalyst; the palladium salt was palladium chloride; the copper salt was copper sulfate; the alcohol was ethanol; and the intensity of the irradiation source was 5–50 KGy.

6. The preparation method according to claim 1, characterized in that: In steps 1) through 4), the vacuum drying temperature is 50 ℃ to 70 ℃; the drying time is 6 to 12 h.

7. The application of the magnetic Fe3O4@SiO2@PNIPAM supported PdCu catalyst prepared by any of the methods described in claims 1-6 in the catalytic hydrogenation reduction of chloronitrobenzene.

8. A method for the catalytic hydrogenation reduction of chloronitrobenzene using a magnetic Fe3O4@SiO2@PNIPAM supported PdCu catalyst prepared by any one of claims 1-6, characterized in that... Includes the following steps: A magnetic Fe3O4@SiO2@PNIPAM supported PdCu catalyst, chloronitrobenzene, and ammonia borane were added to a reaction flask. Then, a mixed solvent of ethanol and water was added under stirring at 25 °C to carry out the reduction reaction. After the reaction was completed, the reaction solution was removed after cooling.

9. The method for catalytic hydrogenation reduction of chloronitrobenzene as described in claim 8, characterized in that: The chloronitrobenzene is m-chloronitrobenzene, o-chloronitrobenzene, or p-chloronitrobenzene; the mass of the magnetic Fe3O4@SiO2@PNIPAM supported PdCu catalyst is 1~30 mg.

10. The method for catalytic hydrogenation reduction of chloronitrobenzene as described in claim 8, characterized in that: The amount of ethanol added in the mixed solvent is 20-100%; the amount of ammonia borane introduced is 0.5-2 mmol; the reaction time for the hydrogenation reduction of chloronitrobenzene is 2-60 min; and the mass ratio of Fe3O4@SiO2@PNIPAM supported PdCu catalyst to chloronitrobenzene and ammonia borane is 5:78:16-62.

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