Pd nanodendritic structure, and preparation method and application thereof
The Pd nano-dendritic catalyst prepared by the oil-water interface synthesis method solves the problem of selective hydrogenation of nitrobenzaldehyde in the prior art, and realizes the efficient and selective catalytic preparation of p-aminobenzaldehyde, with the advantages of high activity and low energy consumption.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- HENAN UNIV OF SCI & TECH
- Filing Date
- 2024-02-28
- Publication Date
- 2026-07-03
AI Technical Summary
Existing technologies struggle to efficiently catalytically reduce nitrobenzaldehyde to p-aminobenzaldehyde under mild conditions, and the catalysts lack selectivity and activity.
Pd nanodendritic structures were prepared by an oil-water interface synthesis method. By preparing dendritic nanomaterials at the liquid-liquid interface in one step, the growth and assembly of Pd nanodendritic structures were regulated by the ionic liquid 1-butylpyridine chloride (BPyC) and used for the selective hydrogenation reaction of p-nitrobenzaldehyde.
The catalyst achieves high selectivity and high conversion rate of p-nitrobenzaldehyde to p-aminobenzaldehyde under mild conditions. The catalyst has high activity and selectivity, and the operation is simple and energy consumption is low.
Smart Images
Figure CN118080874B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of noble metal nanomaterials technology, specifically relating to a Pd nanodendritic structure, its preparation method, and its application. Background Technology
[0002] Metal nanomaterials have attracted much attention due to their unique physical and chemical properties and wide applications in catalysis and electronics. Among them, palladium (Pd) nanomaterials exhibit excellent catalytic performance in many organic reactions. Their surface active sites show high selectivity for hydrogen adsorption and dissociation, which is of great significance for controlling specific functional groups in organic reactions. In existing technologies, some methods utilize alkali lignin-phenolic resins to directly reduce and stabilize Pd nanoparticles in an aqueous phase. This catalyst can efficiently catalyze the hydrogenation and deoxygenation of vanillin under mild conditions. p-Aminobenzaldehyde is an important intermediate in organic synthesis, and the green, efficient, and selective synthesis methods are crucial for organic synthesis. Highly selective preparation of p-aminobenzaldehyde can be achieved through the catalytic reduction of nitrobenzaldehyde, thus providing an economical and environmentally friendly route for organic synthesis. The key is to achieve the preparation of catalysts with high catalytic activity and high selectivity. Summary of the Invention
[0003] To address the aforementioned issues, this invention proposes a Pd nanodendritic structure, its preparation method, and its application. The catalyst prepared by a simple and efficient oil-water interface synthesis method exhibits excellent catalytic activity and selectivity in the selective hydrogenation of p-nitrobenzaldehyde to p-aminobenzaldehyde.
[0004] This invention is achieved through the following technical solution:
[0005] A method for preparing Pd nanodendritic structures includes the following steps:
[0006] Step 1: Cut the glass slide into squares, soak them in the mixed solution to remove surface impurities, then clean them with anhydrous ethanol and set aside.
[0007] Step 2: Weigh 1-butylpyridine chloride and dissolve it in chloroform solution, then add 1-naphthol and dissolve it to prepare a chloroform mixture, which will be used as the oil phase in the reaction system for later use.
[0008] Step 3: Weigh the Pd precursor and add it to distilled water to prepare a precursor solution, which will be used as the aqueous phase in the reaction system for later use.
[0009] Step 4: Place the glass slide from Step 1 into the cylindrical vial and set aside.
[0010] Step 5: Take the chloroform mixture from Step 2 and add it to the vial from Step 4. Then add the precursor solution from Step 3 to form an oil-water two-phase reaction system and let it stand to react.
[0011] Step 6: Slowly extract the organic phase and transfer the product to the glass slide from Step 4. Then extract the aqueous solution, soak the obtained film in anhydrous ethanol, extract it, repeat this process several times, and then dry it to prepare the Pd nanodendritic structure loaded on the glass slide.
[0012] Furthermore, in step one, the size of the block is 1cm × 1cm.
[0013] Furthermore, the mixed solution in step one includes hydrogen peroxide and concentrated sulfuric acid, wherein the volume ratio of hydrogen peroxide to concentrated sulfuric acid is 1:1.
[0014] Furthermore, in step two, the concentration of 1-butylpyridine chloride is 100 mM, and the concentration of 1-naphthol is 10-50 mM.
[0015] Furthermore, the Pd precursor in step three is Na2PdCl4, and its concentration in the aqueous phase is 1-5 mM.
[0016] Furthermore, in step four, the diameter of the cylindrical vial is 2.1~2.3cm.
[0017] Furthermore, in step five, the reaction is allowed to stand for 72 hours, and the reaction temperature is 10-40℃.
[0018] This invention provides a Pd nanodendritic structure, prepared by the above method, with a length of 1.5~1.7μm and having complete root, trunk, branch and leaf structures.
[0019] This invention also provides an application of Pd nanodendritic structures in catalysts, specifically in the selective hydrogenation of p-nitrobenzaldehyde to prepare p-aminobenzaldehyde. The process involves dispersing 1.5 mg of Pd nanodendritic structures in 1 mL of anhydrous ethanol, adding this to 4 mL of anhydrous ethanol containing 0.25 mol of p-nitrobenzaldehyde, mixing the solutions thoroughly, and reacting at 35°C under a normal pressure H2 atmosphere. Samples are taken at different time points and analyzed using gas chromatography-mass spectrometry (GC-MS).
[0020] The beneficial effects of this invention are as follows:
[0021] 1) The oil-water interface synthesis method is a simple, mild and effective synthesis method. One precursor is dissolved in the oil phase and another precursor is dissolved in the water phase. The two precursors diffuse to the interface between the two phases via ion transport. Under the regulation of the liquid-liquid interface, nucleation, growth and ordered assembly are carried out. Nanomaterials with special morphology and excellent properties that are difficult to obtain by other methods can be prepared.
[0022] This invention employs an oil-water interface synthesis method that eliminates the need for strict reaction conditions such as seeds, hard templates, high temperature, and high pressure. The method is simple to operate and has low energy consumption. Furthermore, this invention utilizes a two-phase reaction system formed by chloroform and water to prepare a dendritic nanomaterial at the liquid-liquid interface in one step. This dendritic structure grows vertically side by side at the liquid-liquid interface and assembles into a thin film structure material, which exhibits high catalytic activity and selectivity in the hydrogenation of p-nitrobenzaldehyde to p-aminobenzaldehyde.
[0023] 2) The ionic liquid 1-butylpyridine chloride (BPyC) used in this invention has amphiphilic properties and a moderate alkyl chain length, which enables it to exist at the liquid-liquid interface, regulate the microstructure of the liquid-liquid interface reaction region, and thus effectively control the growth and assembly of Pd nanodendritic structures.
[0024] 3) The Pd nanodendritic structure of the present invention has the characteristics of high catalytic activity and high selectivity. Attached Figure Description
[0025] Figure 1 This is a SEM image of the Pd nanodendritic structure prepared in Example 3 of the present invention, magnified 50,000 times.
[0026] Figure 2 This is a SEM image of the Pd nanodendritic structure prepared in Example 3 of the present invention, magnified 100,000 times.
[0027] Figure 3 This is a TEM image of the Pd nanodendritic structure prepared in Example 3 of the present invention;
[0028] Figure 4 The image shows the XRD pattern of the Pd nanodendritic structure prepared in Example 3 of this invention.
[0029] Figure 5 The graph shows the changes in conversion rate and selectivity of the Pd nano-dendritic structure catalyzing the hydrogenation of p-nitrobenzaldehyde as described in Example 3 of this invention over time. Detailed Implementation
[0030] A method for preparing Pd nanodendritic structures includes the following steps:
[0031] Step 1: Cut the glass slide into 1cm×1cm squares, soak them in a mixed solution of hydrogen peroxide and concentrated sulfuric acid (volume ratio 1:1) to remove surface impurities, then clean them with anhydrous ethanol and set aside.
[0032] Step 2: Weigh 1-butylpyridine chloride (BPyC) and dissolve it in chloroform solution. Then add 1-naphthol and dissolve it to prepare a chloroform mixture as the oil phase in the reaction system for later use. The concentration of 1-butylpyridine chloride is 100 mM and the concentration of 1-naphthol is 10-50 mM.
[0033] Step 3: Weigh the Pd precursor and add it to distilled water to prepare a precursor solution, which will be used as the aqueous phase in the reaction system for later use; the Pd precursor is Na2PdCl4, and its concentration in the aqueous phase is 1-5 mM.
[0034] Step 4: Place the glass slide from Step 1 into a cylindrical vial with a diameter of 2.1~2.3cm, and set aside.
[0035] Step 5: Take 4 mL of the chloroform mixture from Step 2 and add it to the vial from Step 4. Then add 4 mL of the precursor solution from Step 3 to form an oil-water two-phase reaction system. Let the reaction stand for 72 hours, and the reaction temperature is 10-40℃.
[0036] Step 6: Slowly extract the organic phase with a syringe and transfer the product to the glass slide from Step 4. Then extract the aqueous solution, soak the obtained film in anhydrous ethanol, extract it, repeat the process several times, and then dry it to prepare the Pd nanodendritic structure loaded on the glass slide.
[0037] This invention provides a Pd nano-dendritic structure, prepared by the above method. The dendritic structure is 1.5~1.7μm long and has complete root, trunk, branch and leaf structure, which is very similar to a tree growing in nature.
[0038] This invention also provides an application of Pd nanodendritic structures as catalysts in selective hydrogenation reactions. Specifically, it is applied to the selective hydrogenation of p-nitrobenzaldehyde to prepare p-aminobenzaldehyde. The process involves dispersing 1.5 mg of Pd nanodendritic structures in 1 mL of anhydrous ethanol, adding this to 4 mL of anhydrous ethanol containing 0.25 mol of p-nitrobenzaldehyde, mixing the solutions thoroughly, and reacting at 35°C under a normal pressure H2 atmosphere. Samples are taken at different time points and analyzed using gas chromatography-mass spectrometry (GC-MS).
[0039] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.
[0040] Example 1:
[0041] 1) Cut the glass slide into 1cm×1cm squares, soak them in a mixed solution of hydrogen peroxide and concentrated sulfuric acid in a volume ratio of 1:1 to remove surface impurities, and then clean them with anhydrous ethanol.
[0042] 2) Weigh a certain amount of BPyC and dissolve it in chloroform solution to a concentration of 100 mM. Then add a certain amount of 1-naphthol and dissolve it to a concentration of 10 mM, which will be used as the oil phase in the reaction system.
[0043] 3) Weigh a certain amount of Na2PdCl4 and add it to distilled water to prepare a 1 mM precursor solution, which will be used as the aqueous phase in the reaction system;
[0044] 4) Place the glass slide from step one into a cylindrical vial with a diameter of approximately 2.2 cm;
[0045] 5) Take 4 mL of the chloroform mixture from step 2) and add it to the vial from step 4), then add 4 mL of the precursor solution from step 3) to form an oil-water interface two-phase reaction system. Let it stand at 40°C for 72 h.
[0046] 6) Slowly extract the organic phase with a syringe and transfer the product to the glass slide of step 4). Then extract the aqueous solution, soak the obtained film in anhydrous ethanol, extract it, and repeat this process 3 times to prepare the Pd nanodendritic structure loaded on the glass slide.
[0047] Example 2:
[0048] 1) Cut the glass slide into 1cm×1cm squares, soak them in a mixed solution of hydrogen peroxide and concentrated sulfuric acid in a volume ratio of 1:1 to remove surface impurities, and then clean them with anhydrous ethanol.
[0049] 2) Weigh a certain amount of BPyC and dissolve it in chloroform solution to a concentration of 100 mM. Then add a certain amount of 1-naphthol and dissolve it to a concentration of 30 mM, which will be used as the oil phase in the reaction system.
[0050] 3) Weigh a certain amount of Na2PdCl4 and add it to distilled water to prepare a 4 mM precursor solution, which will be used as the aqueous phase in the reaction system;
[0051] 4) Place the glass slide from step one into a cylindrical vial with a diameter of approximately 2.2 cm;
[0052] 5) Take 4 mL of the chloroform solution from step 2) and add it to the vial from step 4), then add 4 mL of the precursor solution from step 3) to form an oil-water interface two-phase reaction system. Let it stand at 25°C for 72 h.
[0053] 6) Slowly extract the organic phase with a syringe and transfer the product to the glass slide of step 4). Then extract the aqueous solution, soak the obtained film in anhydrous ethanol, extract it, and repeat this process 3 times to prepare the Pd nanodendritic structure loaded on the glass slide.
[0054] Example 3:
[0055] 1) Cut the glass slide into 1cm×1cm squares, soak them in a mixed solution of hydrogen peroxide and concentrated sulfuric acid in a volume ratio of 1:1 to remove surface impurities, and then clean them with anhydrous ethanol.
[0056] 2) Weigh a certain amount of BPyC and dissolve it in chloroform solution to a concentration of 100 mM. Then add a certain amount of 1-naphthol and dissolve it to a concentration of 40 mM, which will be used as the oil phase in the reaction system.
[0057] 3) Weigh a certain amount of Na2PdCl4 and add it to distilled water to prepare a 5 mM precursor solution, which will be used as the aqueous phase in the reaction system;
[0058] 4) Place the glass slide from step one into a cylindrical vial with a diameter of approximately 2.2 cm;
[0059] 5) Take 4 mL of the chloroform solution from step 2) and add it to the vial from step 4), then add 4 mL of the precursor solution from step 3) to form an oil-water interface two-phase reaction system. Let it stand at 40°C for 72 h.
[0060] 6) Slowly extract the organic phase with a syringe and transfer the product to the glass slide of step 4). Then extract the aqueous solution, soak the obtained film in anhydrous ethanol, extract it, and repeat this process 3 times to prepare the Pd nanodendritic structure loaded on the glass slide.
[0061] The Pd product prepared in this invention is approximately 1.6 μm long and has a uniform morphology. SEM and TEM images show that it possesses a complete root, trunk, branch, and leaf-like structure, closely resembling a tree growing in nature. This uniquely morphological Pd nanomaterial not only has a high specific surface area and abundant active sites, but also serves as a self-supporting hierarchical structure, avoiding the need for a carrier in its application. X-ray diffraction (XRD) patterns reveal that the Pd nanodendritic structure is face-centered cubic, with no other impurity peaks besides the Pd peak, indicating high purity.
[0062] Example 4:
[0063] 1) Cut the glass slide into 1cm×1cm squares, immerse them in a solution of hydrogen peroxide and concentrated sulfuric acid in a 1:1 ratio to remove surface impurities, and then clean them with anhydrous ethanol.
[0064] 2) Weigh a certain amount of BPyC and dissolve it in chloroform solution to a concentration of 100 mM. Then add a certain amount of 1-naphthol and dissolve it to a concentration of 20 mM, which will be used as the oil phase in the reaction system.
[0065] 3) Weigh a certain amount of Na2PdCl4 and add it to distilled water to prepare a 5 mM precursor solution, which will be used as the aqueous phase in the reaction system;
[0066] 4) Place the glass slide from step one into a cylindrical vial with a diameter of approximately 2.2 cm;
[0067] 5) Take 4 mL of the chloroform solution from step 2) and add it to the vial from step 4), then add 4 mL of the precursor solution from step 3) to form an oil-water interface two-phase reaction system. Let it stand at 10°C for 72 h.
[0068] 6) Slowly extract the organic phase with a syringe and transfer the product to the glass slide of step 4). Then extract the aqueous solution, soak the obtained film in anhydrous ethanol, extract it, and repeat this process 3 times to prepare the Pd nanodendritic structure loaded on the glass slide.
[0069] This invention also provides an application of Pd nanodendritic structures as catalysts in selective hydrogenation reactions. Specifically, it is applied to the selective hydrogenation of p-nitrobenzaldehyde to prepare p-aminobenzaldehyde. The process involves dispersing 1.5 mg of Pd nanodendritic structures in 1 mL of anhydrous ethanol, adding this to 4 mL of anhydrous ethanol containing 0.25 mol of p-nitrobenzaldehyde, mixing the solutions thoroughly, and reacting at 35°C under a normal pressure H2 atmosphere. Samples are taken at different time points and analyzed using gas chromatography-mass spectrometry (GC-MS).
[0070] In the selective hydrogenation of p-nitrobenzaldehyde to p-aminobenzaldehyde, the Pd nanodendritic structure prepared in this invention exhibits excellent catalytic activity. The reaction is carried out in anhydrous ethanol at 35°C and atmospheric pressure, under mild conditions and with a small catalyst dosage. After 120 min of reaction, the conversion rate of p-nitrobenzaldehyde reaches as high as 97.29%, and the selectivity of p-aminobenzaldehyde reaches as high as 98.12%. This indicates that the catalyst possesses excellent catalytic activity and selectivity.
[0071] It should be noted that although the present invention has been described through the above embodiments, the present invention may have many other embodiments. Without departing from the spirit and scope of the present invention, those skilled in the art can obviously make various corresponding changes and modifications to the present invention, but all such changes and modifications should fall within the scope of protection of the appended claims and their equivalents.
Claims
1. A method for preparing Pd nanodendritic structures, characterized in that: Includes the following steps: Step 1: Cut the glass slide into squares, soak them in the mixed solution to remove surface impurities, then clean them with anhydrous ethanol and set aside. Step 2: Weigh 1-butylpyridine chloride and dissolve it in chloroform solution, then add 1-naphthol and dissolve it to prepare a chloroform mixture, which will be used as the oil phase in the reaction system for later use. Step 3: Weigh the Pd precursor and add it to distilled water to prepare a precursor solution, which will be used as the aqueous phase in the reaction system for later use. Step 4: Place the glass slide from Step 1 into the cylindrical vial and set aside. Step 5: Take the chloroform mixture from Step 2 and add it to the vial from Step 4. Then add the precursor solution from Step 3 to form an oil-water two-phase reaction system and let it stand to react. Step 6: Slowly extract the organic phase and transfer the product to the glass slide from Step 4. Then extract the aqueous solution, soak the obtained film in anhydrous ethanol, extract it, repeat this process several times, and then dry it to prepare the Pd nanodendritic structure loaded on the glass slide.
2. The method for preparing a Pd nanodendritic structure according to claim 1, characterized in that: In step one, the size of the square is 1cm × 1cm.
3. The method for preparing a Pd nanodendritic structure according to claim 1, characterized in that: The mixed solution in step one includes hydrogen peroxide and concentrated sulfuric acid, with a volume ratio of 1:
1.
4. The method for preparing a Pd nanodendritic structure according to claim 1, characterized in that: In step two, the concentration of 1-butylpyridine chloride is 100 mM, and the concentration of 1-naphthol is 10-50 mM.
5. The method for preparing a Pd nanodendritic structure according to claim 1, characterized in that: The Pd precursor in step three is Na2PdCl4, and its concentration in the aqueous phase is 1-5 mM.
6. The method for preparing a Pd nanodendritic structure according to claim 1, characterized in that: In step four, the diameter of the cylindrical vial is 2.1~2.3cm.
7. The method for preparing a Pd nanodendritic structure according to claim 1, characterized in that: In step five, the reaction is allowed to stand for 72 hours, and the reaction temperature is 10-40℃.
8. A Pd nanodendritic structure, characterized in that: The tree-like structure, prepared by any one of claims 1 to 7, has a length of 1.5 to 1.7 μm and has complete root, trunk, branch and leaf-like structures.
9. The application of the Pd nanodendritic structure according to claim 8 in a catalyst, characterized in that: It was applied to the selective hydrogenation of p-nitrobenzaldehyde to prepare p-aminobenzaldehyde. Specifically, 1.5 mg of Pd nano-dendritic structure was dispersed in 1 mL of anhydrous ethanol and added to 4 mL of anhydrous ethanol containing 0.25 mol of p-nitrobenzaldehyde. The solution was mixed evenly and the reaction was carried out at 35℃ under normal pressure and H2 atmosphere. Samples were taken out at different time periods and analyzed by gas chromatography-mass spectrometry.