Graphdiyne-coated two-dimensional palladium metalloene catalyst and its preparation method and application

Abstract

The present invention discloses a graphene-coated two-dimensional palladium metal ene catalyst and its preparation method and application, which belongs to the field of electrocatalytic material technology, wherein the preparation method comprises the following steps: adding palladium metal ene with a two-dimensional planar structure to pyridine to obtain a pyridine solution containing palladium metal ene; dissolving hexaethynylbenzene monomer in pyridine, then adding it to the pyridine solution containing palladium metal ene, reacting at a temperature of 105-115°C to obtain a reaction product; filtering and washing the reaction product to obtain the graphene-coated two-dimensional palladium metal ene catalyst. The graphene-coated two-dimensional palladium metal ene catalyst provided by the present invention can be applied in the field of electrocatalytic ethylene glycol synthesis of glycolic acid, can still maintain a high product selectivity at a higher potential, can improve the effective current density of glycolic acid synthesis, and thus improve the yield.

Description

Technical Field

[0001] The present invention relates to the technical field of electrocatalytic materials, and in particular to a graphyne-coated two-dimensional palladium metalloene catalyst, and a preparation method and application thereof. Background Art

[0002] Plastics are widely used in packaging, construction, medical applications, and electronics due to their low density, stability to chemicals like acids, bases, and salts, and ease of processing. However, the stability of plastic's chemical structure makes it difficult to recycle. Polyethylene terephthalate (PET) production has reached approximately 1 billion tons, with an annual growth rate of tens of millions of tons. However, only 20% is recycled, with the majority ending up in landfills or incineration, causing serious environmental problems.

[0003] Hydrolyzing PET in an alkaline environment into terephthalic acid (TPA) and ethylene glycol (EG) monomers, followed by electrocatalytic oxidation of EG to high-value-added products, is considered the optimal solution. Ethylene glycol, a potential product, possesses high added value and is a raw monomer for the synthesis of biodegradable plastic polyethylene glycol. Electrocatalytic conversion is considered an ideal material processing method due to its clean, sustainable nature and mild reaction conditions.

[0004] Traditional anode catalyst materials such as precious metals (palladium, platinum, gold, etc.) have certain oxidation activity and controllable CC bond breaking ability, and are considered to be ideal catalyst choices, but they are easily oxidized at high potentials, resulting in deactivation. Summary of the Invention

[0005] The object of the present invention is to provide a method for preparing a graphyne-coated two-dimensional palladium metalloene catalyst to solve the problems raised in the above background technology.

[0006] To achieve the above objectives, the embodiments of the present invention provide the following technical solutions:

[0007] A method for preparing a two-dimensional palladium metalloene catalyst coated with graphene, comprising the following steps:

[0008] adding palladium metalloene with a two-dimensional planar structure into pyridine to obtain a pyridine solution containing palladium metalloene;

[0009] Dissolving hexaethynylbenzene monomer in pyridine, then adding the mixture to a pyridine solution containing palladium metal olefin, and reacting at a temperature of 105-115° C. to obtain a reaction product;

[0010] The reaction product is filtered and washed to obtain the graphyne-coated two-dimensional palladium metal olefin catalyst.

[0011] Preferably, palladium metalloene is replaced by rhodium metalloene or ruthenium metalloene.

[0012] Preferably, the mass ratio of the palladium metal olefin to the hexaethynylbenzene monomer is 1:(2-4).

[0013] Preferably, the method for preparing the palladium metalloalkene comprises the following steps:

[0014] Acetylacetonate palladium, carbonyl chromium and ascorbic acid are dissolved in oleylamine, reacted at a temperature of 70-90° C., and then washed to obtain palladium metal olefin with a two-dimensional planar structure.

[0015] Preferably, the mass ratio of palladium acetylacetonate, carbonyl chromium, and ascorbic acid is (6-10):(15-25):(40-60).

[0016] Another object of an embodiment of the present invention is to provide a graphyne-coated two-dimensional palladium metal olefin catalyst prepared by the above-mentioned preparation method.

[0017] Another object of an embodiment of the present invention is to provide an application of the above-mentioned graphyne-coated two-dimensional palladium metal olefin catalyst in alcohol oxidation.

[0018] Another object of an embodiment of the present invention is to provide an application of the above-mentioned graphyne-coated two-dimensional palladium metal olefin catalyst in the electrocatalytic synthesis of glycolic acid from ethylene glycol.

[0019] The graphyne-coated two-dimensional palladium metal olefin catalyst provided by the present invention can be used in the field of electrocatalytic synthesis of glycolic acid from ethylene glycol. It can still maintain a high product selectivity at a relatively high potential, and can increase the effective current density of the synthesis of glycolic acid, thereby improving the yield. Specifically, due to the presence of graphyne, the electronic structure of palladium can be adjusted, and the proportion of oxidized palladium can be reduced at high potentials to prevent catalyst deactivation. The catalyst has the advantages of a simple preparation process, good selectivity, and resistance to deactivation at relatively high potentials, and is a strong candidate for the future electrosynthesis of glycolic acid. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 are the X-ray diffraction patterns of various materials; in the figure, a is the X-ray diffraction pattern of palladium metalloene; b is the X-ray diffraction pattern of graphyne; c is the X-ray diffraction pattern of graphyne-coated two-dimensional palladium metalloene catalyst.

[0021] Figure 2 are the X-ray photoelectron spectra of each material; in the figure, a is the X-ray photoelectron spectrum of graphyne-coated two-dimensional palladium metalloene catalyst; b is the X-ray photoelectron spectrum of palladium metalloene.

[0022] Figure 3 are transmission electron microscope images of each material; in the figure, a is a transmission electron microscope image of graphyne-coated two-dimensional palladium metalloene catalyst; b is a transmission electron microscope image of palladium metalloene.

[0023] Figure 4 This is a high-resolution transmission electron microscope image of the graphyne-coated two-dimensional palladium metalloene catalyst and the energy-dispersive X-ray spectrum of Pd and C elements; in the figure, a is a high-resolution transmission electron microscope image; b is an energy-dispersive X-ray spectrum.

[0024] Figure 5 This is a comparison chart of the Faradaic efficiency of graphyne-coated two-dimensional palladium metalloene catalyst, palladium metalloene and commercial palladium-carbon catalyst at different potentials.

[0025] Figure 6 This is a stability comparison chart of graphyne-coated two-dimensional palladium metalloene catalyst, palladium metalloene and commercial palladium-carbon catalyst. DETAILED DESCRIPTION

[0026] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0027] In response to the shortcomings of existing materials at high potentials, the embodiments of the present invention provide a graphyne-coated two-dimensional palladium metalloene catalyst, which includes palladium metalloene with a two-dimensional planar structure and graphyne with a two-dimensional planar structure. The embodiments of the present invention adjust the electronic structure of palladium at high potentials by introducing carbon-based materials to prevent excessive oxidation, and have broad application prospects.

[0028] Specifically, in one embodiment of the present invention, a method for preparing a Graphdiyne-coated two-dimensional palladium metalloene catalyst is provided, comprising the following steps:

[0029] S1. dissolving palladium acetylacetonate, carbonyl chromium, and ascorbic acid in oleylamine, reacting at 70-90° C., and then washing to obtain a palladium metalloene with a two-dimensional planar structure;

[0030] S2. adding the palladium metalloene having the two-dimensional planar structure to pyridine to obtain a pyridine solution containing the palladium metalloene;

[0031] S3, dissolving hexaethynylbenzene monomer in pyridine, then adding the mixture to a pyridine solution containing palladium metal olefin, and reacting at a temperature of 105-115° C. to obtain a reaction product;

[0032] S4. Filter and wash the reaction product to obtain a graphyne-coated two-dimensional palladium metal olefin catalyst.

[0033] The mass ratio of palladium acetylacetonate, carbonyl chromium and ascorbic acid is (6-10):(15-25):(40-60); the mass ratio of palladium metal olefin and hexaethynylbenzene monomer is 1:(2-4).

[0034] The graphyne-coated two-dimensional palladium metal olefin catalyst prepared above can be used for alcohol oxidation, specifically for the electrocatalytic synthesis of high-value-added glycolic acid from ethylene glycol; it can also be used in electrocatalytic fields such as carbon dioxide reduction, oxygen reduction reaction, and oxygen evolution reaction.

[0035] It should be noted that the above preparation method is also applicable to the coating of other two-dimensional metal olefin materials such as rhodium metal olefin or ruthenium metal olefin by carbon materials such as graphyne; correspondingly, it is only necessary to replace palladium metal olefin with rhodium metal olefin or ruthenium metal olefin.

[0036] Example 1: This example provides a method for preparing a two-dimensional palladium metalloene catalyst coated with graphene, comprising the following steps:

[0037] S1. Dissolve 8 mg of palladium acetylacetonate, 20 mg of carbonyl chromium, and 50 mg of ascorbic acid in 5 mL of oleylamine, transfer the solution to a sealed glass bottle, stir at room temperature until dissolved, then place in an oil bath or water bath, react at 80°C for 12 hours, and then wash to obtain a two-dimensional planar structure of palladium metalloene;

[0038] S2. adding the palladium metalloene having the two-dimensional planar structure to pyridine to obtain a pyridine solution containing the palladium metalloene;

[0039] S3, dissolving 60 mg of hexaethynylbenzene monomer in 150 mL of pyridine, then adding the mixture to a pyridine solution containing 20 mg of palladium metalloene, and reacting at 110° C. for 48 hours to obtain a reaction product;

[0040] S4. Filter and wash the above reaction product to obtain a graphyne-coated two-dimensional palladium metal olefin catalyst.

[0041] Example 2: This example provides a method for preparing a two-dimensional palladium metalloene catalyst coated with graphene, comprising the following steps:

[0042] S1. Dissolve 6 mg of palladium acetylacetonate, 15 mg of carbonyl chromium, and 40 mg of ascorbic acid in 5 mL of oleylamine. Transfer the solution to a sealed glass bottle and stir at room temperature until dissolved. Then place the solution in an oil bath or water bath and react at 70°C for 12 hours. Then, wash the solution to obtain a two-dimensional planar structure of palladium metalloene.

[0043] S2. adding the palladium metalloene having the two-dimensional planar structure to pyridine to obtain a pyridine solution containing the palladium metalloene;

[0044] S3, dissolving 40 mg of hexaethynylbenzene monomer in 150 mL of pyridine, then adding the mixture to a pyridine solution containing 20 mg of palladium metalloene, and reacting at 105° C. for 48 hours to obtain a reaction product;

[0045] S4. Filter and wash the above reaction product to obtain a graphyne-coated two-dimensional palladium metal olefin catalyst.

[0046] Example 3: This example provides a method for preparing a two-dimensional palladium metalloene catalyst coated with graphene, comprising the following steps:

[0047] S1. Dissolve 10 mg of palladium acetylacetonate, 25 mg of carbonyl chromium, and 60 mg of ascorbic acid in 5 mL of oleylamine. Transfer the solution to a sealed glass bottle and stir at room temperature until dissolved. Then place the solution in an oil bath or water bath and react at 90°C for 12 hours. Then, wash the solution to obtain a two-dimensional planar structure of palladium metalloene.

[0048] S2. adding the palladium metalloene having the two-dimensional planar structure to pyridine to obtain a pyridine solution containing the palladium metalloene;

[0049] S3, dissolving 80 mg of hexaethynylbenzene monomer in 150 mL of pyridine, then adding the mixture to a pyridine solution containing 20 mg of palladium metalloene, and reacting at 115° C. for 48 hours to obtain a reaction product;

[0050] S4. Filter and wash the above reaction product to obtain a graphyne-coated two-dimensional palladium metal olefin catalyst.

[0051] Example 4: This example provides a method for preparing a two-dimensional palladium metalloene catalyst coated with graphene, comprising the following steps:

[0052] S1. Dissolve 7 mg of palladium acetylacetonate, 22 mg of carbonyl chromium, and 45 mg of ascorbic acid in 5 mL of oleylamine. Transfer the solution to a sealed glass bottle and stir at room temperature until dissolved. Then place the solution in an oil bath or water bath and react at 75°C for 12 hours. Then, wash the solution to obtain a two-dimensional planar structure of palladium metalloene.

[0053] S2. adding the palladium metalloene having the two-dimensional planar structure to pyridine to obtain a pyridine solution containing the palladium metalloene;

[0054] S3, dissolving 50 mg of hexaethynylbenzene monomer in 150 mL of pyridine, then adding the mixture to a pyridine solution containing 20 mg of palladium metalloene, and reacting at 108° C. for 48 hours to obtain a reaction product;

[0055] S4. Filter and wash the above reaction product to obtain a graphyne-coated two-dimensional palladium metal olefin catalyst.

[0056] Example 5: This example provides a method for preparing a Graphdiyne-coated two-dimensional palladium metalloene catalyst, comprising the following steps:

[0057] S1. Dissolve 8 mg of palladium acetylacetonate, 18 mg of carbonyl chromium, and 55 mg of ascorbic acid in 5 mL of oleylamine. Transfer the solution to a sealed glass bottle and stir at room temperature until dissolved. Then place the solution in an oil bath or water bath and react at 85°C for 12 hours. Then, wash the solution to obtain a two-dimensional planar palladium metalloene.

[0058] S2. adding the palladium metalloene having the two-dimensional planar structure to pyridine to obtain a pyridine solution containing the palladium metalloene;

[0059] S3, dissolving 70 mg of hexaethynylbenzene monomer in 150 mL of pyridine, then adding the mixture to a pyridine solution containing 20 mg of palladium metalloene, and reacting at 112° C. for 48 hours to obtain a reaction product;

[0060] S4. Filter and wash the above reaction product to obtain a graphyne-coated two-dimensional palladium metal olefin catalyst.

[0061] Comparative Example 1: This comparative example provides a method for preparing palladium metal olefin, comprising the following steps: dissolving palladium acetylacetonate, carbonyl chromium, and ascorbic acid in oleylamine, reacting at a temperature of 70-90°C, and then washing to obtain palladium metal olefin with a two-dimensional planar structure.

[0062] Performance test: 1. X-ray diffraction test was performed on the graphene-coated two-dimensional palladium metalloene catalyst (Pd@GDY) prepared in Example 1, the palladium metalloene (Pd) prepared in Comparative Example 1, and graphene (GDY) synthesized from hexaethynylbenzene monomer. The results are as follows: Figure 1 As shown in the figure, it can be seen that the X-ray diffraction pattern of the 2D palladium metalloene catalyst coated with Graphyne prepared in accordance with the present invention is consistent with the standard palladium card, but a new peak appears at 22 degrees. By comparing it with the X-ray diffraction pattern of Graphyne, the presence of Graphyne can be confirmed, indicating the successful synthesis of the material. At the same time, by comparing the peak positions of the 2D palladium metalloene catalyst coated with Graphyne and palladium metalloene, it is found that there is no shift between the two, indicating that the coating of Graphyne has no effect on the structure of the palladium metalloene.

[0063] 2. The graphene-coated two-dimensional palladium metalloene catalyst (Pd@GDY) prepared in Example 1 and the palladium metalloene (Pd) prepared in Comparative Example 1 were subjected to X-ray photoelectron spectroscopy test. The results are as follows: Figure 2As shown in the figure, both the 2D Pd metalloenide catalyst and the Pd metalloenide catalyst, with metallic Pd predominating in both cases and a small amount of oxidized Pd, are present. The presence of oxidized Pd is due to slight oxidation on the surface of the material. Comparing the peak positions of the two, the Graphyne-coated material exhibits a negative shift compared to the Pd metalloenide, demonstrating electron transfer between the Pd metalloenide and Graphyne.

[0064] 3. The graphene-coated two-dimensional palladium metalloene catalyst (Pd@GDY) prepared in Example 1 and the palladium metalloene (Pd) prepared in Comparative Example 1 were observed by transmission electron microscopy. The results are as follows: Figure 3 As shown; it can be seen from the figure that before coating with graphyne, palladium metalloene presents a two-dimensional sheet structure, and after coating with graphyne, palladium metalloene still maintains the original two-dimensional sheet structure.

[0065] 4. The Graphene-coated two-dimensional palladium metalloene catalyst prepared in Example 1 was observed by high-resolution transmission electron microscopy (HRTEM). Figure 4 As shown in a; Energy dispersive X-ray (EDS) test was carried out at the same time, and the results were as follows Figure 4 As shown in b; it can be seen from the figure that amorphous C can be seen at the edge of palladium metallograph, which was determined to be graphyne through Raman testing; the uniform distribution of Pd and C elements can be seen through EDS energy spectrum.

[0066] 5. The Faraday efficiency of the graphene-coated two-dimensional palladium metalloene catalyst (Pd@GDY) prepared in Example 1, the palladium metalloene (Pd) prepared in Comparative Example 1, and the commercial palladium-carbon catalyst (Com.Pd) were compared at different potentials. The results are as follows: Figure 5 As shown; it can be seen from the figure that the graphyne-coated two-dimensional palladium metal olefin catalyst prepared in the embodiment of the present invention has a higher Faraday efficiency at a higher potential.

[0067] 6. The stability of the graphene-coated two-dimensional palladium metalloene catalyst (Pd@GDY) prepared in Example 1, the palladium metalloene (Pd) prepared in Comparative Example 1, and the commercial palladium-carbon catalyst (Com.Pd) were tested and compared. The results are as follows: Figure 6 As shown; it can be seen from the figure that after two hours of reaction, the graphyne-coated two-dimensional palladium metal olefin catalyst prepared in the embodiment of the present invention still maintains a relatively high current density.

[0068] In summary, the graphyne-coated two-dimensional palladium metalloenite catalyst prepared in the embodiment of the present invention can maintain a higher product selectivity at a higher potential compared with palladium metalloenite and commercial palladium-carbon catalysts, and can increase the effective current density of the synthesis of ethanolic acid, thereby improving the yield.

[0069] In addition, the graphyne-coated two-dimensional palladium metalloene catalyst prepared in the embodiment of the present invention can prevent CO poisoning. Compared with palladium metalloene, it has stronger CO resistance and can prevent catalyst poisoning.

[0070] Therefore, the graphyne-coated two-dimensional palladium metal olefin catalyst prepared in the embodiment of the present invention can be used in the electrocatalytic synthesis of glycolic acid from ethylene glycol derived from PET, thereby promoting the effective recycling and upgrading of PET waste.

[0071] Based on the above-mentioned ideal embodiment of the present invention, and through the above description, relevant personnel can make various changes and modifications without departing from the scope of the technical concept of the present invention. The technical scope of the present invention is not limited to the contents of the specification.

Claims

1. A method for preparing a graphene-coated two-dimensional palladium metalloene catalyst, characterized in that: The following steps are involved: adding palladium metalloene with a two-dimensional planar structure into pyridine to obtain a pyridine solution containing palladium metalloene; Dissolving hexaethynylbenzene monomer in pyridine, then adding the mixture to a pyridine solution containing palladium metal olefin, and reacting at a temperature of 105-115° C. to obtain a reaction product; The reaction product is filtered and washed to obtain the graphyne-coated two-dimensional palladium metal olefin catalyst.

2. The method for preparing the graphene-coated two-dimensional palladium metalloene catalyst according to claim 1, wherein The palladium metalloene is replaced by a rhodium metalloene or a ruthenium metalloene.

3. The method for preparing the graphene-coated two-dimensional palladium metalloene catalyst according to claim 1, wherein: The mass ratio of the palladium metal olefin to the hexaethynylbenzene monomer is 1:(2-4).

4. The method for preparing the graphene-coated two-dimensional palladium metalloene catalyst according to claim 1 or 3, wherein: The preparation method of the palladium metal olefin comprises the following steps: Acetylacetonate palladium, carbonyl chromium and ascorbic acid are dissolved in oleylamine, reacted at a temperature of 70-90° C., and then washed to obtain palladium metal olefin with a two-dimensional planar structure.

5. The method for preparing the Graphdiyne-coated two-dimensional palladium metalloene catalyst according to claim 4, wherein: The mass ratio of the palladium acetylacetonate, carbonyl chromium and ascorbic acid is (6-10):(15-25):(40-60).

6. A graphene-coated two-dimensional palladium metalloene catalyst prepared by the preparation method according to any one of claims 1 and 3-5.

7. Use of the graphene-coated two-dimensional palladium metalloene catalyst as claimed in claim 6 in alcohol oxidation.

8. Use of the graphyne-coated two-dimensional palladium metalloene catalyst as claimed in claim 6 in the electrocatalytic synthesis of glycolic acid from ethylene glycol.

9. A graphene-coated two-dimensional rhodium or ruthenium metalloene catalyst prepared by the preparation method according to claim 2.

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