Preparation method of supported heterogeneous palladium catalyst and application of supported heterogeneous palladium catalyst in catalysis of Heck coupling reaction

Abstract

The invention discloses a preparation method of a supported heterogeneous palladium catalyst and application of the supported heterogeneous palladium catalyst in catalyzing a Heck coupling reaction. The preparation method comprises the following steps: modifying carboxymethyl chitosan by using an amino triazole compound, and compounding the modified carboxymethyl chitosan with starch to obtain a composite carrier with multiple coordination sites of hydroxyl, azolyl and other complexing groups (one of carboxyl, sulfydryl and amino); a plurality of capture sites on the composite carrier and palladium salt are subjected to a complexation reaction to obtain the nitrogen functionalized chitosan / starch composite carrier loaded palladium catalyst, and the nitrogen functionalized chitosan / starch composite carrier loaded palladium catalyst is applied to catalysis of a Heck coupling reaction. By means of the synergistic effect of a plurality of capture sites on the composite carrier and palladium ions, the catalytic activity and the cycle stability of the catalyst are effectively enhanced, the loss of metal active components in the reaction process is reduced, and the cyclic utilization performance of the catalyst is further enhanced. In the preparation process, carboxymethyl chitosan and starch are used as raw materials, so that the method has the advantages of wide source, degradability and environmental friendliness.

Description

Technical Field

[0001] This invention belongs to the field of heterogeneous catalytic Heck coupling reaction technology, specifically relating to a method for preparing a supported heterogeneous palladium catalyst and its application in catalyzing Heck coupling reactions. Background Technology

[0002] The Heck coupling reaction is an important method for constructing unsaturated carbon-carbon double bonds. Since the 1970s, this reaction has shown great industrial and commercial potential in the synthesis of drug molecules, natural products, and new materials. Palladium-based catalysts play an indispensable role in this reaction. However, homogeneous Pd catalysts for this reaction suffer from drawbacks such as difficulty in separating them from the reaction mixture and inability to be reused, leading to environmental pollution and resource waste.

[0003] While heterogeneous Pd catalysts overcome the drawbacks of separation and metal contamination, some still suffer from complex preparation processes, low catalytic efficiency, weak binding between the catalyst support and palladium active sites, and easy aggregation and detachment of active components during the reaction, leading to the loss of metal active components and resulting in low stability. To improve the binding ability between the support and the metal active components and increase the number of metal active component attachment sites, functional modification of the support is necessary. Precise control of functional groups and reduction of preparation steps are required to simplify production and lower costs. Therefore, for the Heck coupling reaction, precise screening of suitable supports and design of highly efficient chelating ligand molecules to enhance the binding sites and capabilities of metal active components are crucial for overcoming the performance bottlenecks of heterogeneous catalysts and are the core requirements for promoting the industrialization of this technology.

[0004] Patent document CN202510616156.0 discloses a chitosan-based coupling reaction catalyst, its preparation method, and its application. Modified chitosan with multiple complexing sites (imine, carboxyl, and hydroxyl groups) is prepared by modifying chitosan with aromatic aldehydes and halocarboxylic acids. This modified chitosan is then used as a support, and the support is further complexed with palladium salts through trapping sites to prepare a functional chitosan-supported Pd complex catalyst. Through multi-site synergistic complexation, this catalyst exhibits excellent catalytic efficiency and stability in coupling reactions. Relying on multi-site complexation of metal Pd, the metal loss after multiple recycling cycles is less than 0.1%, overcoming the drawback of easy metal loss in traditional heterogeneous catalytic systems. However, the patented technology does not contain any record of using aminotriazole compounds to modify carboxymethyl chitosan and then combining it with starch to obtain a multi-coordination site composite support material with hydroxyl, azole and other complexing groups. In addition, there is no record of preparing a azole-functionalized chitosan / starch composite support for loading palladium catalyst by complexing the above composite support with palladium salt through the capture site and applying it to the catalytic Heck coupling reaction.

[0005] Patent document CN201110345147.0 discloses a chitosan porous microsphere-supported cuprous iodide catalyst, its preparation method, and its application. The catalyst support is chitosan-based porous microspheres with a diameter of 0.5–3 mm, a surface pore size of 5–30 nm, and an internal pore size of 1–10 μm. The active component is cuprous iodide, with a mass percentage of 10%–30% of the support. The aforementioned chitosan porous microsphere-supported cuprous iodide catalyst exhibits good and stable performance in catalyzing Heck coupling reactions, which helps reduce costs and environmental pollution. However, this patent does not describe the use of aminotriazole compounds to modify carboxymethyl chitosan and then composite it with starch to obtain a multi-coordination site composite support material with hydroxyl, azole, and other complexing groups. Furthermore, it does not describe the preparation of an azole-functionalized chitosan / starch composite support palladium catalyst by complexing the aforementioned composite support with palladium salts through trapping sites, and its application in catalyzing Heck coupling reactions. Summary of the Invention

[0006] To overcome the technical problems existing in the catalysis of Heck coupling reaction by Pd-based catalysts in the prior art, this invention provides a method for preparing a highly active, highly stable and economically prepared supported heterogeneous palladium catalyst and its application in catalyzing Heck coupling reaction. It effectively solves the problems of easy loss of active metal components in catalysts, complex preparation process, low catalytic efficiency and poor stability in the prior art, and meets the requirements of green chemistry and sustainable development.

[0007] Carboxymethyl chitosan and starch possess advantages such as biodegradability, biocompatibility, availability, and non-toxicity, making them suitable as support materials. Furthermore, both have abundant active groups on their surfaces, making them easily modifiable and functionalized, thus facilitating the complexation of metal particles. Triazole ligands readily complex metals and can be used to prepare catalysts with high activity and stability. Therefore, the azole-functionalized carboxymethyl chitosan and starch composite support material prepared in this invention has multiple binding sites, enabling effective complexation with Pd to ultimately obtain a supported heterogeneous palladium catalyst. This catalyst exhibits advantages such as low cost, easy separation, strong metal binding ability, and high stability, meeting the requirements of green catalysis.

[0008] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: a method for preparing a supported heterogeneous palladium catalyst, the specific preparation steps of which are as follows:

[0009] Step S1: Carboxymethyl chitosan and potassium carbonate are stirred and reacted in N,N-dimethylformamide (DMF) at 70-100°C. Then, a solution of triazole compound in N,N-dimethylformamide is added, and the reaction is stirred under an inert gas atmosphere. After the reaction is completed, the mixture is cooled to room temperature, and then filtered, washed and dried to obtain triazole-functionalized chitosan.

[0010] Step S2: Mix the azole-functionalized chitosan and starch obtained in step S1 with acetic acid solution until homogeneous, and stir and react at 25-75°C under an inert gas atmosphere. After the reaction is completed, filter, wash and dry to obtain the azole-functionalized chitosan / starch composite carrier.

[0011] Step S3: The azole-functionalized chitosan / starch composite support obtained in step S2 is mixed with palladium salt in a solvent, and then stirred and reacted at 25-75°C under an inert gas atmosphere. After the reaction is completed, the mixture is filtered, washed and dried to obtain the azole-functionalized chitosan / starch composite support palladium catalyst, i.e., the supported heterogeneous palladium catalyst. The synergistic effect of multiple capture sites of the composite support and palladium ions in this catalyst effectively enhances the catalytic activity and cycle stability of the catalyst, reduces the loss of metal active components during the reaction, and enhances the recyclability of the catalyst.

[0012] Furthermore, in step S1, the stirring reaction time at 70–100°C is 1–5 h, and the stirring reaction time under an inert gas atmosphere is 12–36 h.

[0013] Furthermore, the triazole compound mentioned in step S1 is at least one of 3,5-diamino-1,2,4-triazole, 3-amino-5-mercapto-1,2,4-triazole, or 3-amino-1H-1,2,4-triazole-5-carboxylic acid.

[0014] Furthermore, in step S1, the washing process involves sequentially washing with N,N-dimethylformamide and anhydrous ethanol, with a drying temperature of 50–80°C and a drying time of 12 hours.

[0015] Furthermore, in step S2, the feeding ratio of azole-functionalized chitosan, starch, and acetic acid solution is 1g:0.8-1.2g:80-120mL, wherein the concentration of acetic acid solution is 1wt%-3wt%.

[0016] Furthermore, the stirring reaction time in step S2 is 10–18 h.

[0017] Furthermore, the palladium salt mentioned in step S3 is at least one of sodium chloropalladium, palladium acetate, palladium dichloride, or palladium nitrate, and the solvent is at least one of water, ethanol, acetonitrile, or tetrahydrofuran.

[0018] Furthermore, in step S3, the mass ratio of the palladium salt to the azole-functionalized chitosan / starch composite carrier is 1:2 to 1:10, and the stirring reaction time is 12 to 36 hours.

[0019] Furthermore, the inert gas in steps S1, S2 and S3 is at least one of nitrogen or argon.

[0020] The application of the supported heterogeneous palladium catalyst described in this invention in the catalytic Heck coupling reaction.

[0021] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0022] (1) The raw materials of the composite carrier selected in this invention are natural polysaccharide materials carboxymethyl chitosan and starch, which are abundant, green and biodegradable and inexpensive, and have environmental friendliness and cost controllability.

[0023] (2) Carboxymethyl chitosan has abundant free hydroxyl, amino and carboxyl groups on its surface, and starch has abundant free hydroxyl groups on its surface. This is beneficial for the functional modification of the support surface, and can also improve the binding ability with palladium metal ions, increase the loading rate of metal active components, reduce the loss of Pd during the reaction, and improve the stability of the catalyst.

[0024] (3) Using aminotriazole compounds as ligands, the compounds can react with the carboxyl groups on the surface of carboxymethyl chitosan, and then combine with starch through hydrogen bonding. This results in the composite support possessing multiple capture sites, including azole groups, hydroxyl groups, and other complexing groups (one of carboxyl, mercapto, and amino groups). The synergistic effect of these multiple capture sites with palladium ions effectively enhances the catalytic activity and cycle stability of the catalyst, reduces the loss of active metal components during the reaction, and improves the recyclability of the catalyst. This contributes to the construction of high-performance heterogeneous palladium catalytic systems, overcomes technical bottlenecks, and promotes the industrial application of Heck coupling reactions. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the synthesis route of the catalyst in Example 1.

[0026] Figure 2 SEM images of the catalyst in Example 1: (a) carboxymethyl chitosan, (b) azole-functionalized carboxymethyl chitosan, (c) starch, (d) azole-functionalized carboxymethyl chitosan / starch composite support, and (e) palladium catalyst supported on azole-functionalized carboxymethyl chitosan / starch composite support.

[0027] Figure 3 SEM images of the fresh (a) and recycled (b) catalysts in Example 1.

[0028] Figure 4 This is a TEM image of the catalyst obtained in Example 1.

[0029] Figure 5 This is a comparison chart of the catalytic activity and Pd content of the fresh catalyst in Example 1, the catalyst after 5 cycles in Example 1, the catalyst in Comparative Example 1, and the catalyst in Comparative Example 2 under the same reaction conditions. Detailed Implementation

[0030] The following examples further illustrate the above-described content of the present invention, but it should not be construed as limiting the scope of the subject matter of the present invention to the following examples. All technologies implemented based on the above-described content of the present invention fall within the scope of the present invention.

[0031] Example 1

[0032] (1) Mix 2g of carboxymethyl chitosan with 5mmol of K2CO3 in DMF and stir at 90℃ for 1h. Then slowly add a DMF solution containing 10mmol of 3,5-diamino-1,2,4-triazole to the above solution. Continue the reaction for 24h under an argon atmosphere. After the reaction is completed, filter the solution and wash the solid powder with DMF and anhydrous ethanol in sequence. Then dry the solid powder under vacuum at 50℃ for 12h to obtain azole-functionalized chitosan.

[0033] (2) Place 1g of azole-functionalized chitosan obtained in step (1) and 1g of starch in 100mL of 2wt% acetic acid solution and stir at room temperature for 12h under argon atmosphere. After the reaction is completed, filter, wash and dry to obtain azole-functionalized chitosan / starch composite carrier.

[0034] (3) The composite support obtained in step (2) was mixed with 0.2g of palladium chloride in H2O and stirred at room temperature for 12h under argon atmosphere. After the reaction was completed, the mixture was filtered, washed, and then dried under vacuum at 50℃ overnight to obtain the azole-functionalized carboxymethyl chitosan / starch composite support palladium catalyst.

[0035] Example 2

[0036] (1) Mix 2g of carboxymethyl chitosan with 5mmol of K2CO3 in DMF and stir at 70℃ for 5h. Then slowly add a DMF solution containing 10mmol of 3-amino-5-mercapto-1,2,4-triazole to the above solution. Continue the reaction for 36h under a nitrogen atmosphere. After the reaction is completed, filter the solution and wash the solid powder with DMF and anhydrous ethanol in sequence. Then dry the solid powder under vacuum at 60℃ for 12h to obtain azole-functionalized chitosan.

[0037] (2) Place 1g of azole-functionalized chitosan obtained in step (1) and 0.8g of starch in 80mL of 1wt% acetic acid solution and stir at 50℃ for 18h under argon atmosphere. After the reaction is completed, filter, wash and dry to obtain azole-functionalized chitosan / starch composite carrier.

[0038] (3) The composite support obtained in step (2) was mixed with 0.4 g of palladium nitrate in H2O and reacted at 50 °C for 36 h under an argon atmosphere. After the reaction was completed, the mixture was filtered, washed, and then dried under vacuum at 50 °C overnight to obtain the azole-functionalized carboxymethyl chitosan / starch composite support palladium catalyst.

[0039] Example 3

[0040] (1) Mix 2g of carboxymethyl chitosan with 5mmol of K2CO3 in DMF and stir at 100℃ for 2h. Then slowly add a DMF solution containing 10mmol of 3-amino-1H-1,2,4-triazole-5-carboxylic acid to the above solution. Continue the reaction for 12h under a nitrogen atmosphere. After the reaction is completed, filter the solution and wash the solid powder with DMF and anhydrous ethanol in sequence. Then dry it under vacuum at 80℃ for 12h to obtain azole-functionalized chitosan.

[0041] (2) Place 1g of azole-functionalized chitosan obtained in step (1) and 1.2g of starch in 120mL of 3wt% acetic acid solution and stir at 75℃ for 16h under nitrogen atmosphere. After the reaction is completed, filter, wash and dry to obtain azole-functionalized chitosan / starch composite carrier.

[0042] (3) The composite support obtained in step (2) was mixed with 0.5 g of palladium acetate in acetonitrile and reacted at 75 °C for 24 h under a nitrogen atmosphere. After the reaction was completed, the mixture was filtered, washed, and then dried under vacuum at 50 °C overnight to obtain the azole-functionalized carboxymethyl chitosan / starch composite support palladium catalyst.

[0043] Example 4

[0044] (1) Mix 2g of carboxymethyl chitosan with 5mmol of K2CO3 in DMF and stir at 80℃ for 3h. Then slowly add a DMF solution containing 10mmol of 3,5-diamino-1,2,4-triazole to the above solution. Continue the reaction for 24h under an argon atmosphere. After the reaction is completed, filter the solution and wash the solid powder with DMF and anhydrous ethanol in sequence. Then dry it under vacuum at 70℃ for 12h to obtain azole-functionalized chitosan.

[0045] (2) Place 1g of azole-functionalized chitosan obtained in step (1) and 0.9g of starch in 90mL of 2wt% acetic acid solution and stir at 60℃ for 14h under argon atmosphere. After the reaction is completed, filter, wash and dry to obtain azole-functionalized chitosan / starch composite carrier.

[0046] (3) The composite support obtained in step (2) was mixed with 0.25 g sodium chloropalladium in ethanol and reacted at 60 °C for 12 h under an argon atmosphere. After the reaction was completed, the mixture was filtered, washed, and then dried under vacuum at 50 °C overnight to obtain the azole-functionalized carboxymethyl chitosan / starch composite support for palladium catalyst.

[0047] Example 5

[0048] (1) Mix 2g of carboxymethyl chitosan with 5mmol of K2CO3 in DMF and stir at 70°C for 4h. Then slowly add a DMF solution containing 10mmol of 3-amino-1H-1,2,4-triazole-5-carboxylic acid to the above solution. Continue the reaction for 12h under a nitrogen atmosphere. After the reaction is completed, filter the solution and wash the solid powder with DMF and anhydrous ethanol in sequence. Then dry the solid powder under vacuum at 50°C for 12h to obtain azole-functionalized chitosan.

[0049] (2) Place 1g of azole-functionalized chitosan obtained in step (1) and 1.1g of starch in 110mL of 3wt% acetic acid solution and stir at 60℃ for 10h under nitrogen atmosphere. After the reaction is completed, filter, wash and dry to obtain azole-functionalized chitosan / starch composite carrier.

[0050] (3) The composite support obtained in step (2) was mixed with 1g of palladium acetate in tetrahydrofuran and reacted at 60°C for 24h under a nitrogen atmosphere. After the reaction was completed, the mixture was filtered, washed, and then vacuum dried at 50°C overnight to obtain the azole-functionalized carboxymethyl chitosan / starch composite support palladium catalyst.

[0051] Comparative Example 1

[0052] 2g of starch and 0.2g of palladium chloride were mixed in water and reacted at room temperature under an argon atmosphere for 12h. After the reaction was completed, the mixture was filtered, washed, and then dried under vacuum at 50℃ overnight to obtain a starch-supported palladium catalyst.

[0053] Comparative Example 2

[0054] (1) Mix 2g of carboxymethyl chitosan with 5mmol of K2CO3 in DMF and stir at 90℃ for 1h. Then slowly add a DMF solution containing 10mmol of 3,5-diamino-1,2,4-triazole to the above solution. Continue the reaction for 24h under an argon atmosphere. After the reaction is completed, filter the solution and wash the solid powder with DMF and anhydrous ethanol in sequence. Then dry the solid powder under vacuum at 50℃ for 12h to obtain azole-functionalized chitosan.

[0055] (2) Mix 2g of azole-functionalized chitosan obtained in step (1) with 0.2g of palladium chloride in water, stir and react at room temperature for 12h under argon atmosphere, and then vacuum dry at 50℃ overnight to obtain azole-functionalized carboxymethyl chitosan supported palladium catalyst.

[0056] The catalysts prepared in Examples 1-5 and Comparative Examples 1-2 were used to catalyze the Heck coupling reaction to evaluate their catalytic performance. The steps of the Heck coupling reaction are as follows:

[0057] An aryl halide (0.25 mmol), an active olefin (0.375 mmol), Na₂CO₃ (1 mmol), and the catalyst prepared in Examples 1-5 were added to a 25 mL reaction flask, followed by 5 mL of DMSO solvent. The reaction was carried out under air with stirring at a controlled temperature. After the reaction was complete, the product was separated, washed, and purified to obtain the target product.

[0058] Catalyst recycling reaction: After the reaction is complete, the catalyst and reaction solution are separated by centrifugation. The catalyst is then thoroughly washed with ethanol and distilled water to remove residual substrate and inorganic matter. The catalyst is then used directly in the next cycle experiment without any further treatment.

[0059] The catalytic performance of the catalysts prepared in Examples 1 to 5 is shown in Table 1.

[0060] Table 1 shows the Heck coupling reaction between aryl halides and active olefins catalyzed by the catalysts prepared in Examples 1-5.

[0061]

[0062]

[0063]

[0064]

[0065] Note: Numbers 1-30 are fresh catalysts from Examples 1-5, number 31 is catalyst from Comparative Example 1, number 32 is catalyst from Comparative Example 2, and numbers 33-37 are catalysts from Examples 1-5 recycled for the 5th time.

[0066] As shown in Table 1, the catalysts prepared in Examples 1-5 exhibit excellent performance in the Heck coupling reaction between aryl halides and active olefins, with product yields all exceeding 90% and demonstrating broad applicability. Furthermore, the recycling results show that all catalysts prepared in Examples 1-5 maintained yields of over 84% after five cycles, demonstrating excellent recyclability and thus excellent cycle stability.

[0067] SEM images of samples from the catalyst preparation process in Example 1 ( Figure 2 As can be seen, when triazole modifies carboxymethyl chitosan, its surface becomes rougher and a blocky structure appears. Figure 2 (b)). Compared to pure starch ( Figure 2 In the modified composite material (c), not only does the starch exhibit a spherical structure, but the modified chitosan also exhibits a blocky structure. Figure 2 (d)). After loading the metal, the roughness increases ( Figure 2(e)). The above changes indicate the successful preparation of the azole-modified chitosan / starch composite support and the successful synthesis of the corresponding catalyst. After multiple cycles, the catalyst structure did not change significantly, demonstrating the catalyst's high stability, which is one of the reasons for its good cycling performance. Figure 3 Analysis of its TEM images reveals that ( Figure 4 Pd is uniformly distributed in ionic form on the surface of the composite carrier.

[0068] In addition, by Figure 5 It can be seen that, compared with the starch-supported palladium catalyst of Comparative Example 1 (palladium loading 0.26 wt% and catalytic activity 69%) and the azole-modified chitosan-supported palladium catalyst of Comparative Example 2 (palladium loading 0.32 wt% and catalytic activity 74%), the azole-functionalized carboxymethyl chitosan / starch composite support palladium catalyst of Example 1 has a higher palladium loading (0.76 wt%) and better catalytic activity (98%). Furthermore, after 5 cycles, the palladium loading was 0.72 wt%. These results are mainly related to the strong bonding and coordination between the hydroxyl, azole, and amino complex groups and palladium. In summary, thanks to the interaction between multiple active sites and Pd, the heterogeneous palladium catalysts in Table 1 exhibit excellent catalytic performance and recyclability in the Heck coupling reaction, possessing practical application capabilities and meeting the development requirements of economic practicality and green environmental protection.

[0069] The above embodiments describe the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are only illustrative of the principles of the present invention. Various changes and modifications can be made to the present invention without departing from the scope of the principles of the present invention, and all such changes and modifications fall within the protection scope of the present invention.

Claims

1. A method for preparing a supported heterogeneous palladium catalyst, characterized in that... The specific preparation steps are as follows: Step S1: Carboxymethyl chitosan and potassium carbonate are stirred and reacted in N,N-dimethylformamide at 70~100 °C. Then, an N,N-dimethylformamide solution of aminotriazole compounds is added, and the reaction is stirred under an inert gas atmosphere. After the reaction is completed, the mixture is cooled to room temperature, and then filtered, washed and dried to obtain azole-functionalized chitosan. Step S2: Mix the azole-functionalized chitosan and starch obtained in step S1 with acetic acid solution until homogeneous, and stir and react at 25~75 °C under an inert gas atmosphere. After the reaction is completed, filter, wash and dry to obtain the azole-functionalized chitosan / starch composite carrier. In step S3, the azole-functionalized chitosan / starch composite support obtained in step S2 is mixed with palladium salt in a solvent, and then stirred and reacted at 25~75 °C under an inert gas atmosphere. After the reaction is completed, the mixture is filtered, washed and dried to obtain the azole-functionalized chitosan / starch composite support palladium catalyst, i.e., the supported heterogeneous palladium catalyst. The synergistic effect between the multiple capture sites of the composite support and palladium ions in this catalyst effectively enhances the catalytic activity and cycle stability of the catalyst, reduces the loss of metal active components during the reaction, and enhances the recyclability of the catalyst.

2. The method for preparing the supported heterogeneous palladium catalyst according to claim 1, characterized in that: In step S1, the stirring reaction time at 70~100 ℃ is 1~5 h, and the stirring reaction time under an inert gas atmosphere is 12~36 h.

3. The method for preparing the supported heterogeneous palladium catalyst according to claim 1, characterized in that: The triazole compound mentioned in step S1 is at least one of 3,5-diamino-1,2,4-triazole, 3-amino-5-mercapto-1,2,4-triazole, or 3-amino-1H-1,2,4-triazole-5-carboxylic acid.

4. The method for preparing the supported heterogeneous palladium catalyst according to claim 1, characterized in that: In step S1, the washing process involves sequentially washing with N,N-dimethylformamide and anhydrous ethanol, with a drying temperature of 50~80 ℃ and a drying time of 12 h.

5. The method for preparing the supported heterogeneous palladium catalyst according to claim 1, characterized in that: In step S2, the feeding ratio of azole-functionalized chitosan, starch and acetic acid solution is 1g:0.8~1.2g:80~120 mL, wherein the concentration of acetic acid solution is 1 wt%~3 wt%.

6. The method for preparing the supported heterogeneous palladium catalyst according to claim 1, characterized in that: The stirring reaction time in step S2 is 10~18 h.

7. The method for preparing the supported heterogeneous palladium catalyst according to claim 1, characterized in that: The palladium salt mentioned in step S3 is at least one of sodium chloropalladium, palladium acetate, palladium dichloride, or palladium nitrate, and the solvent is at least one of water, ethanol, acetonitrile, or tetrahydrofuran.

8. The method for preparing the supported heterogeneous palladium catalyst according to claim 1, characterized in that: In step S3, the mass ratio of palladium salt to azole-functionalized chitosan / starch composite carrier is 1:2 to 1:10, and the stirring reaction time is 12 to 36 hours.

9. The method for preparing the supported heterogeneous palladium catalyst according to claim 1, characterized in that: The inert gas in steps S1, S2 and S3 is at least one of nitrogen or argon.

10. The application of the supported heterogeneous palladium catalyst prepared by the method according to any one of claims 1 to 9 in the catalytic Heck coupling reaction.

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