Magnetic supported molybdenum-based catalyst, preparation method and application

Abstract

The invention discloses a magnetic supported molybdenum-based catalyst as well as a preparation method and application thereof, and belongs to the field of organic synthesis catalysis. The preparation method comprises the following steps: taking FeCl3 and ZrOCl2. 8H2O as metal precursors, and preparing a ZrO2-Fe2O3 carrier by adopting a coprecipitation method; ammonium molybdate tetrahydrate is used as a precursor of molybdenum, molybdenum metal is loaded on the ZrO2-Fe2O3 carrier through an impregnation method, and the magnetic loaded molybdenum-based catalyst is prepared. The method for catalyzing carboxylic acid and amine to prepare amide is suitable for a continuous flow reactor and a traditional batch-type reaction device. In a continuous flow reactor, the catalyst does not need to be frequently separated in the reaction process, and the catalyst still keeps high activity after long-time operation. After phenylpropionic acid and n-hexylamine are catalyzed to react for 100 hours in a continuous flow reactor, more than 3 g of product can be generated, and excellent catalytic stability and cycle performance are shown while high yield is kept.

Description

Technical Field

[0001] The present invention belongs to the field of organic synthesis catalysis, and in particular relates to a magnetic supported molybdenum-based catalyst, a preparation method and an application thereof in catalyzing the condensation of acid and amine to prepare amide. Background Art

[0002] As the chemical industry increasingly demands green and efficient synthesis processes, traditional methods for preparing amides through acid-amine condensation have gradually exposed numerous problems. These include difficulties in catalyst recovery, low reaction yields, and poor process continuity. These issues not only lead to high production costs but also generate large amounts of waste, placing significant pressure on the environment. Therefore, the development of novel catalytic systems and synthesis processes to achieve efficient and sustainable production of amides has become a key issue urgently needed in the chemical industry.

[0003] Currently, homogeneous catalysts or non-magnetic heterogeneous catalysts are often used in the process of preparing amides by condensing acid and amine. Although homogeneous catalysts are highly active, they are difficult to separate and cannot be reused, resulting in waste of resources and environmental pollution. Although non-magnetic heterogeneous catalysts can be separated by filtration and other methods, they are easily deactivated during long-term reactions, making it difficult to maintain a stable catalytic effect, resulting in a decrease in yield. At the same time, traditional processes often rely on batch reaction devices, which have low production efficiency and are difficult to meet the needs of industrial large-scale continuous production. In addition, existing processes are difficult to achieve high levels of catalyst stability and yield, which limits the further development of amide synthesis technology. Therefore, there is an urgent need to develop a new amide synthesis technology that has both high stability and high yield and is suitable for continuous production. Summary of the Invention

[0004] In response to the problems of low catalyst yield, poor stability, and difficulty in recovery in the current process of preparing amides by condensing acids and amines, the present invention aims to provide a magnetically supported molybdenum-based catalyst and a preparation method thereof. The prepared catalyst exhibits high yield, easy recovery, and high stability in both batch reactors and continuous flow reactors when catalyzing the condensation of acids and amines to prepare amides, providing a feasible catalyst for large-scale continuous production of amides.

[0005] To achieve the above object, the technical solution adopted by the present invention is as follows: In a first aspect, the present invention provides a method for preparing a magnetic supported molybdenum-based catalyst, comprising: Step 1: Using FeCl3 and ZrOCl2·8H2O as metal precursors, a ZrO2-Fe2O3 support was prepared by co-precipitation method; Step 2: Using ammonium molybdate tetrahydrate as a precursor of molybdenum, molybdenum metal is loaded on a ZrO2-Fe2O3 carrier by an impregnation method to prepare a magnetic supported molybdenum-based catalyst.

[0006] In step 1, the prepared ZrO2-Fe2O3 carrier is metal oxide nanoparticles.

[0007] In step 1, a ZrO2-Fe2O3 carrier is prepared by a coprecipitation method, which specifically includes: FeCl3 and ZrOCl2·8H2O were dissolved in deionized water in a molar ratio of 1:1. Ammonia was added to adjust the pH to 9, and the resulting mixture was heated under vigorous stirring to form a precipitate. The precipitate was allowed to stand and age at room temperature. The solid obtained after separation was dried and calcined to obtain a ZrO2-Fe2O3 support.

[0008] Wherein, the ZrO2-Fe2O3 carrier was prepared by co-precipitation method, the stirring and heating temperature was 115°C, and the stirring and heating time was 5 minutes.

[0009] Among them, the ZrO2-Fe2O3 carrier was prepared by co-precipitation method, and the solid obtained after separation was dried in a vacuum drying oven at a drying temperature of 120°C and a drying time of 24 h.

[0010] Among them, the ZrO2-Fe2O3 carrier was prepared by co-precipitation method, and the solid obtained after drying was calcined in air atmosphere at a calcination temperature of 500℃ and a calcination time of 6 h.

[0011] In step 2, molybdenum metal is loaded on the ZrO2-Fe2O3 carrier by an impregnation method, comprising: Ammonium molybdate tetrahydrate is dissolved in deionized water, ammonia is added to adjust the pH to 8, and then a ZrO2-Fe2O3 carrier is added. The reaction is heated under constant stirring, and then the deionized water is evaporated under reduced pressure to obtain a crude catalyst. The crude catalyst is dried and calcined to obtain a magnetic supported molybdenum-based catalyst.

[0012] The amount of ammonium molybdate tetrahydrate added is such that the molybdenum metal loading in the prepared catalyst is 6% to 18% of the mass of the ZrO2-Fe2O3 carrier.

[0013] Among them, molybdenum metal is loaded on the ZrO2-Fe2O3 carrier by impregnation method, the stirring heating temperature is 70℃, and the stirring heating time is 3 hours.

[0014] Among them, molybdenum metal was loaded on the ZrO2-Fe2O3 carrier by impregnation method, the drying temperature was 110℃, and the drying time was 12 h.

[0015] Molybdenum metal is loaded on a ZrO2-Fe2O3 carrier by an impregnation method, and the resulting solid is dried and calcined in an air atmosphere at a calcination temperature of 500-600°C, preferably 600°C; and the calcination time is 6 h.

[0016] In a second aspect, the present invention provides a magnetic supported molybdenum-based catalyst prepared according to any one of the preparation methods described in the first aspect.

[0017] In the prepared catalyst, the loading amount of molybdenum (relative to the mass of the ZrO2-Fe2O3 carrier) is 6-18%, and most preferably 18%.

[0018] In a third aspect, the present invention provides an application of a magnetically supported molybdenum-based catalyst in catalyzing the condensation of acid and amine to prepare amides, comprising: reacting a substrate acid, an amine, a magnetically supported molybdenum-based catalyst, and a solvent in a batch reactor or a continuous flow reactor to synthesize amides.

[0019] In the batch reaction and continuous flow reaction of preparing amide by condensing acid and amine catalyzed by a magnetic supported molybdenum-based catalyst, the solvent is tetrahydrofuran.

[0020] In the batch reaction and continuous flow reaction of preparing amide by condensation of acid and amine catalyzed by a magnetic supported molybdenum-based catalyst, the acid and amine condensation reaction temperature is 90°C.

[0021] In the batch reaction and continuous flow reaction of preparing amide by condensation of acid and amine catalyzed by a magnetic supported molybdenum-based catalyst, the molar ratio of acid to amine is 1:0.5-2, preferably 1:0.5-1, and most preferably 1:0.5.

[0022] In the batch reaction and continuous flow reaction of preparing amide by condensation of acid and amine catalyzed by a magnetic supported molybdenum-based catalyst, the acid is an aromatic acid and the amine is an aromatic amine or an aliphatic amine.

[0023] In the batch reaction to prepare amide, the mass ratio of acid to catalyst is 5:1.

[0024] In the continuous flow reaction to prepare amides, the catalyst loading was 6 g.

[0025] Compared with the prior art, the present invention has the following beneficial effects: The present invention uses ZrO2-Fe2O3 as a carrier to load 18% Mo(VI) to prepare a magnetic supported metal catalyst, which is then applied to the synthesis of amides in continuous flow reactors and batch reactors. The unique combination of the catalyst carrier and the active component makes it magnetically recyclable, solving the problem of difficult separation of traditional catalysts, greatly reducing production costs, and simultaneously reducing resource waste and environmental pollution. The reaction process does not require frequent catalyst separation; rapid recovery can be achieved solely through a magnetic field, resulting in simple and efficient operation. Furthermore, in a continuous flow reactor, the catalyst can maintain high activity over long periods of operation, avoiding the drawback of traditional non-magnetic heterogeneous catalysts that are prone to deactivation. Furthermore, the continuous flow process replaces batch reactors, significantly improving production efficiency and meeting the requirements of large-scale continuous industrial production. When catalyzing the reaction of phenylpropionic acid with amine compounds, the catalyst can produce over 3 g of product after 100 hours, demonstrating excellent catalytic stability and high yield. This provides an innovative solution for the green and efficient synthesis of amides and has broad prospects for industrial application. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a scanning electron microscope image of the 18% Mo(VI) / ZrO2-Fe2O3-600 catalyst prepared in Example 4; Figure 2 This is an infrared spectrum of the 18% Mo(VI) / ZrO2-Fe2O3-600 catalyst prepared in Example 4; Figure 3 This is a nitrogen adsorption and desorption curve of the 18% Mo(VI) / ZrO2-Fe2O3-600 catalyst prepared in Example 4; Figure 4 Optimized solvent screening diagram for the preparation of amides from phenylpropionic acid and benzylamine catalyzed by the 18% Mo(VI) / ZrO2-Fe2O3-600 catalyst prepared in Example 4; Figure 5 Optimization diagram of substrate molar ratio for the preparation of amide from phenylpropionic acid and benzylamine catalyzed by the 18% Mo(VI) / ZrO2-Fe2O3-600 catalyst prepared in Example 4; Figure 6 This is a catalyst alkali poisoning test chart for the preparation of amide from phenylpropionic acid and benzylamine using the 18% Mo(VI) / ZrO2-Fe2O3-600 catalyst prepared in Example 4; Figure 7 This is a test chart of the optimal catalyst loading for the continuous flow preparation of amides from phenylpropionic acid and benzylamine using the 18% Mo(VI) / ZrO2-Fe2O3-600 catalyst prepared in Example 4; Figure 8The yield-time graph and estimated amide yield-time graph of the preparation of amide from phenylpropionic acid and n-hexylamine catalyzed by the 18% Mo(VI) / ZrO2-Fe2O3-600 catalyst prepared in Example 4; Figure 9 XRD patterns of the catalyst at different time periods during the preparation of amide from phenylpropionic acid and n-hexylamine by the 18% Mo(VI) / ZrO2-Fe2O3-600 catalyst prepared in Example 4. DETAILED DESCRIPTION

[0027] The present invention will be further described below in conjunction with specific examples. The following examples are only used to more clearly illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention.

[0028] It should be noted that, unless otherwise specified, the technical or scientific terms used in this application should have the common meanings understood by those skilled in the art to which the present invention belongs.

[0029] Unless otherwise specified, the raw materials in the examples of the present invention were purchased from commercial sources.

[0030] Example 1

[0031] Step 1: Prepare ZrO2-Fe2O3 carrier by co-precipitation method: 1.62 g (10 mmol) of FeCl₃ was dissolved in 30 mL of deionized water, and 0.5 mL of concentrated HCl was slowly added to the deionized water to form Solution A. 3.22 g (10 mmol) of ZrOCl₂·8H₂O was dissolved in 60 mL of deionized water to form Solution B, which was added dropwise to Solution A. After the addition of Solution B, an excess of 39% ammonia was added to adjust the pH of the mixed solution to 9. The resulting mixture was then heated to 115°C with vigorous stirring for 5 minutes. A reddish-red precipitate immediately formed in the beaker. The suspension was then aged at room temperature for 24 hours. The resulting solid material was filtered and washed with deionized water. The washing step was repeated until no chloride ions could be detected by adding AgNO₃ to the wash filtrate. The resulting sample was dried in a vacuum oven at 120°C for 24 hours. The resulting reddish-red solid was calcined at 500°C in air for 6 hours to prepare the supported ZrO₂-Fe₂O₃ mixed oxide.

[0032] Step 2: Preparation of 6% Mo(VI) / ZrO2-Fe2O3-500 catalyst by impregnation method Dissolve 0.06 g of ammonium molybdate tetrahydrate in 5 mL of deionized water, and add 39% ammonia to maintain a pH of 8. Add 1.0 g of the ZrO₂-Fe₂O₃ support material prepared in Step 1 to this solution, then stir and heat at 70°C for 3 h. The deionized water is then removed by distillation under reduced pressure. The resulting crude catalyst is dried at 110°C for 12 h and calcined at 500°C in air for 6 h to prepare the 6% Mo(VI) / ZrO₂-Fe₂O₃-500 catalyst.

[0033] Example 2

[0034] Preparation of 12% Mo(VI) / ZrO2-Fe2O3-500 catalyst by impregnation method 0.12 g of ammonium molybdate tetrahydrate was dissolved in 5 mL of deionized water, and aqueous ammonia (39%) was added to maintain the solution pH at 8. 1.0 g of the ZrO2-Fe2O3 support material prepared in Example 1 was added to this solution, followed by heating with stirring at 70°C for 3 h. The deionized water was then removed by distillation under reduced pressure. The resulting crude catalyst was dried at 110°C for 12 h and calcined at 500°C in air for 6 h to prepare the 12% Mo(VI) / ZrO2-Fe2O3-500 catalyst.

[0035] Example 3

[0036] Preparation of 18% Mo(VI) / ZrO2-Fe2O3-500 catalyst by impregnation method 0.18 g of ammonium molybdate tetrahydrate was dissolved in 5 mL of deionized water, and aqueous ammonia (39%) was added to maintain the solution pH at 8. 1.0 g of the ZrO2-Fe2O3 support material prepared in Example 1 was added to this solution, followed by heating at 70°C with stirring for 3 hours. The deionized water was then removed by distillation under reduced pressure. The resulting crude catalyst was dried at 110°C for 12 hours and calcined at 500°C in air for 6 hours to prepare the 18% Mo(VI) / ZrO2-Fe2O3-500 catalyst.

[0037] Example 4

[0038] Preparation of 18% Mo(VI) / ZrO2-Fe2O3-600 catalyst by impregnation method Dissolve 0.18 g of ammonium molybdate tetrahydrate in 5 mL of deionized water, and add 39% ammonia to maintain the solution pH at 8. Add 1.0 g of the ZrO2-Fe2O3 support material prepared in Example 1 to this solution, then stir and heat at 70°C for 3 h. The deionized water is then removed by distillation under reduced pressure. The resulting crude catalyst is dried at 110°C for 12 h and calcined at 600°C in air for 6 h to prepare the 18% Mo(VI) / ZrO2-Fe2O3-600 catalyst.

[0039] Figure 1 This is a scanning electron microscope image of the 18% Mo(VI) / ZrO2-Fe2O3-600 catalyst prepared in Example 4. It can be seen from the image that the prepared 18% Mo(VI) / ZrO2-Fe2O3-600 catalyst is nanoparticles.

[0040] Figure 2 The infrared spectrum of the 18% Mo(VI) / ZrO2-Fe2O3-600 catalyst prepared in Example 4 is shown at 3200 cm -1 -3600 cm -1 and 1600 cm -1 There is a very strong band between them, which corresponds to the stretching vibration of hydroxyl groups in the catalyst structure and water molecules, and the bending vibration of (HOH) and (OHO) in the solid structure. Each sample has a peak at 700 cm -1 -800 cm -1 The absorption peak between them is the characteristic band of MoO3, indicating the formation of Mo-O bonds.

[0041] Figure 3 This is a nitrogen adsorption-desorption curve of the 18% Mo(VI) / ZrO2-Fe2O3-600 catalyst prepared in Example 4. From the nitrogen adsorption-desorption curve of the catalyst, it can be seen that the catalyst has mesoporous and microporous structures. The mesoporous structure helps mass transfer, and the microporous structure helps disperse the active sites. The mesopores and micropores can synergistically enhance the catalytic activity.

[0042] Example 5

[0043] The catalyst prepared in the examples was tested for catalytic performance. The test method was as follows: the catalyst was vacuum-dried at 100°C for 1 hour. Subsequently, a certain amount of pretreated catalyst (30 mg), 150.0 mg (1.0 mmol) of phenylpropionic acid, 0.109 mL (1.0 mmol) of benzylamine, and 2.5 mL of tetrahydrofuran were added in sequence as the reaction solvent. The reaction system was allowed to react at 90°C. Preliminary tests were conducted in a 10 mL pressure-resistant reactor equipped with heating and magnetic stirring. The test performance is shown in Table 1.

[0044] Table 1. Performance test table of catalysts prepared under different examples

[0045] As shown in Table 1, the yield of amide prepared from phenylpropionic acid and benzylamine increases with increasing molybdenum metal loading at 500°C. Calcining at 600°C with an 18% molybdenum metal loading slightly increases the catalytic yield. Subsequent examples, unless otherwise specified, use the 18% Mo(VI) / ZrO2-Fe2O3-600 catalyst.

[0046] Example 6

[0047] The optimal reaction solvent for the preparation of amide from phenylpropionic acid and benzylamine was screened using the 18% Mo(VI) / ZrO2-Fe2O3-600 catalyst prepared in Example 4: the catalyst was placed under vacuum drying at 100°C for 1 h. Subsequently, a certain amount of pretreated catalyst (30 mg), 150.0 mg (1.0 mmol) of phenylpropionic acid, 0.109 mL (1.0 mmol) of benzylamine and 2.5 mL of the solvent to be screened were added in sequence as reaction solvents. The above reaction system was reacted at 90°C. Preliminary tests used a 10 mL pressure-resistant reaction tube equipped with heating and magnetic stirring for a kettle reaction, and the test performance was as follows: Figure 4 shown.

[0048] from Figure 4 It can be seen that in the tetrahydrofuran solvent environment, the catalyst shows a yield of up to 96%, which is much better than other screened solvent systems. The following examples all use tetrahydrofuran as the reaction solvent.

[0049] Example 7

[0050] The 18% Mo(VI) / ZrO2-Fe2O3-600 catalyst prepared in Example 4 was used to optimize the substrate molar amount for the amide preparation reaction of phenylpropionic acid and benzylamine: the catalyst was placed under vacuum drying at 100°C for 1 h. Subsequently, a certain amount of pretreated catalyst (30 mg), phenylpropionic acid, benzylamine and 2.5 mL of tetrahydrofuran were added in sequence. The above reaction system was reacted at 90°C. Preliminary tests were carried out in a 10 mL pressure-resistant reaction tube equipped with heating and magnetic stirring for a kettle reaction. The test performance was as follows: Figure 5 shown.

[0051] from Figure 5 It can be found that as the molar ratio of phenylpropionic acid increases to 2:1 (phenylpropionic acid: benzylamine), the yield of amide increases, while when the molar amount of benzylamine increases, the amount of amide produced decreases. The optimal molar ratio of phenylpropionic acid and benzylamine is 2:1.

[0052] Example 8

[0053] Under the optimized experimental conditions, the catalyst was subjected to an alkali poisoning test: the 18% Mo(VI) / ZrO2-Fe2O3-600 catalyst was placed at 100°C and vacuum dried for 1 h. Subsequently, a certain amount of pretreated catalyst (30 mg), 300.0 mg (2.0 mmol) of phenylpropionic acid, 0.109 mL (1.0 mmol) of benzylamine and 2.5 mL of tetrahydrofuran were added in sequence as reaction solvents, and a certain amount of organic base (1 mmol) was added at the same time. The above reaction system was reacted at 90°C. Preliminary tests used a 10 mL pressure-resistant reaction tube equipped with heating and magnetic stirring for a kettle reaction, and the test performance was as follows. Figure 6 shown.

[0054] from Figure 6 It can be found that after adding organic base, the yield of amide formation does not decrease much, which proves the excellent tolerance and stability of 18%Mo(VI) / ZrO2-Fe2O3-600 catalyst in alkaline environment. This performance provides solid experimental support for its application in the industrial preparation reaction of amide.

[0055] Example 9

[0056] The prepared catalyst was tested in a continuous flow reactor to evaluate its stability and performance. The continuous flow reactor is a Yanzheng micro-flow synthesizer-YZFLA. First, the effect of the catalyst filling amount on the amide yield was screened. The specific experimental process is as follows: the catalyst was placed in a vacuum oven for activation for 12 h, and then filled into a stainless steel column reactor with an inner diameter of 10 mm and a length of 100 mm equipped with a filter, and both ends of the column reactor were sealed. The inlet end was connected to the plunger pump through a 1.0 mm (inner diameter) PTFE tube; the outlet end was connected to the receiving flask through a back pressure regulator. The reactor was placed in an aluminum block column heating device, and the reaction temperature was controlled at 90°C. A tetrahydrofuran solution containing 0.2 mol / L phenylpropionic acid and 0.1 mol / L benzylamine was stirred at 0.03 mL min -1 The flow rate enters the column reactor from the pipeline. Before the reaction starts, an appropriate amount of tetrahydrofuran solvent is used to flow through the reaction column to ensure that the catalyst is fully soaked for at least 1 hour, and then the column heater is turned on to raise the system temperature to the preset value. The internal void volume of the column reactor is determined to be 10 mL by measuring the weight difference of the column reactor before and after solvent immersion. After monitoring the plunger pump outlet pressure to rise to 0.1 MPa-0.2 MPa, the flowing solvent is switched to the mixed substrate solution, and the reaction is started at a constant flow rate of 0.03 mL / min. The reaction requires an appropriate equilibrium period to reach a steady state, so samples for yield determination are collected 8 hours after the start of the flow. The results of the catalyst loading on the amide formation yield are shown in Figure 2. Figure 7 shown.

[0057] from Figure 7 It can be found that 6.0 g of the catalyst has a good amide yield; at the same time, after about 20 hours, the yield of amide prepared by condensation of phenylpropionic acid and benzylamine stabilizes at about 50%, showing good yield and stability.

[0058] Example 10

[0059] The benzylamine in Example 9 was replaced with n-hexylamine, and the catalyst filled was 6.0 g. The catalytic performance of the catalyst for fatty amines was investigated. Figure 8 It can be found that the yield of the target amide in the eluate collected after 8 h has exceeded 50%, and the reaction residue of the residual amine substrate is detected to be low. After 32 h, the yield further increased to 80%, and the yield remained almost stable for the subsequent reaction time. More importantly, the catalyst exhibited excellent continuous operation stability: even if the reaction time was significantly extended to 100 h, the amide synthesis yield remained above 80%, with a small fluctuation range. Based on material balance calculations, the continuous flow system can stably synthesize more than 3.0 g of amide product in 100 h, and no signs of catalyst activity decay were observed, which provides a key feasibility basis for industrial scale-up.

[0060] By testing the XRD of the catalyst at different reaction time periods during Example 10, Figure 9 The XRD pattern indicates that the catalyst may have undergone slight structural changes during use, with some Fe detaching from the catalyst surface. However, the catalyst demonstrated good stability during continuous use, laying the foundation for subsequent research on the preparation of amides by acid-amine condensation. It also provides a highly stable, long-lived, and easily recyclable catalyst for the continuous-flow acid-amine condensation preparation of amides.

[0061] The present invention has been disclosed above with preferred embodiments, which are not intended to limit the present invention. Any technical solutions obtained by adopting equivalent replacement or equivalent transformation solutions fall within the protection scope of the present invention.

Claims

1. A method for preparing a magnetic supported molybdenum-based catalyst, characterized in that: include: ZrO2-Fe2O3 support was prepared by co-precipitation method using FeCl3 and ZrOCl2·8H2O as metal precursors; Ammonium molybdate tetrahydrate was used as a molybdenum precursor, and molybdenum metal was loaded on a ZrO2-Fe2O3 carrier by an impregnation method to prepare a magnetic supported molybdenum-based catalyst.

2. The method for preparing a magnetic supported platinum-based catalyst according to claim 1, wherein The ZrO2-Fe2O3 carrier is prepared by a co-precipitation method, comprising: FeCl3 and ZrOCl2·8H2O were dissolved in deionized water in a molar ratio of 1:

1. Ammonia was added to adjust the pH to 9, and the resulting mixture was heated under vigorous stirring to form a precipitate. The precipitate was allowed to stand and age at room temperature. The solid obtained after separation was dried and calcined to obtain a ZrO2-Fe2O3 support.

3. The preparation method of the magnetic supported platinum-based catalyst according to claim 2, wherein The ZrO2-Fe2O3 support is prepared by co-precipitation method and meets one or more of the following requirements: The stirring and heating temperature is 115°C and the stirring and heating time is 5 minutes; The drying temperature is 120°C and the drying time is 24 h; The calcination temperature was 500 °C and the calcination time was 6 h.

4. The method for preparing a magnetic supported platinum-based catalyst according to claim 1, wherein Molybdenum metal is loaded on a ZrO2-Fe2O3 carrier by an impregnation method, including: Ammonium molybdate tetrahydrate is dissolved in deionized water, ammonia is added to adjust the pH to 8, and then a ZrO2-Fe2O3 carrier is added. The reaction is heated under constant stirring, and then the deionized water is evaporated under reduced pressure to obtain a crude catalyst. The crude catalyst is dried and calcined to obtain a magnetic supported molybdenum-based catalyst.

5. The method for preparing a magnetic supported platinum-based catalyst according to claim 4, wherein The amount of ammonium molybdate tetrahydrate added is such that the molybdenum metal loading in the prepared catalyst is 6% to 18% of the mass of the ZrO2-Fe2O3 carrier.

6. The method for preparing a magnetic supported platinum-based catalyst according to claim 4, wherein Molybdenum metal is loaded on a ZrO2-Fe2O3 support by impregnation, satisfying one or more of the following: The stirring and heating temperature is 70°C and the stirring and heating time is 3 h; The drying temperature was 110 °C and the drying time was 12 h; The calcination temperature is 500~600℃ and the calcination time is 6 h.

7. A magnetic supported molybdenum-based catalyst, characterized in that Prepared according to the preparation method according to any one of claims 1 to 6.

8. The use of a magnetic supported platinum-based catalyst according to claim 7 in catalyzing acid-amine condensation to prepare amides, characterized in that: The substrate acid, amine, magnetic supported molybdenum-based catalyst and solvent are reacted in a batch reactor or a continuous flow reactor to synthesize amide.

9. The use according to claim 8, characterized in that Meet one or more of the following: The solvent for the acid-amine condensation reaction is tetrahydrofuran; The acid-amine condensation reaction temperature is 90°C; The molar ratio of acid to amine is 1:0.5~2; The acid is an aromatic acid, and the amine is an aromatic amine or an aliphatic amine.

10. The use according to claim 8, characterized in that In the preparation of amide using a batch reactor, the mass ratio of acid to catalyst was 5:1; in the preparation of amide using a continuous flow reactor, the catalyst loading was 6 g.

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