Supported catalyst having au@pt core-shell structure, and preparation method therefor and use thereof

Abstract

Disclosed in the present invention is a supported catalyst having an Au@Pt core-shell structure, which catalyst comprises a carrier and Au@Pt nanoparticles loaded on the carrier, wherein each Au@Pt nanoparticle is of a core-shell structure, the core layer thereof is Au, the shell layer thereof is Pt, the particle size thereof is 2-10 nm, the diameter of the core layer is 1-3 nm, and the thickness of the shell layer is 1-7 nm. Further disclosed in the present invention are a preparation method for the supported catalyst having an Au@Pt core-shell structure and the use thereof in the oxidation process of alcohols. In the method of the present invention, an alcohol oxidation catalyst can be prepared simply by means of liquid-phase reduction at room temperature, the process is simple and convenient, and the prepared catalyst has a unique core-shell structure and good catalytic activity and stability, and enables a reaction system to achieve, without an extra alkali, the oxidation of alcohols at a high conversion rate so as to obtain corresponding carboxylic acids.

Description

Au@Pt core-shell structure supported catalyst and its preparation method and application Technical Field

[0001] The present invention belongs to the field of industrial catalysis, and in particular relates to an Au@Pt core-shell structure supported catalyst and a preparation method and application thereof. Background Art

[0002] The oxidation process of alcohols is of great importance in the industrial field because it is a key raw material for the manufacture of various ketones, aldehydes, acids and other compounds required for the manufacture of plastics, detergents, paints, cosmetics, food additives and pharmaceutical intermediates.

[0003] Traditional oxidation methods use stoichiometric amounts of inorganic oxidants such as manganese dioxide, hexavalent chromium, or Swern or Dess-Martin reagents. These oxidants are often toxic and produce large amounts of byproducts. Furthermore, many of the catalytic systems investigated earlier suffered from reagent instability, the use of hazardous metals, harsh reaction conditions, complex operation, incompatible functional groups, or the generation of unprocessable waste.

[0004] A variety of catalytic approaches have been discovered for the oxidation of alcohols, including the use of alternative oxidants such as peroxides or oxygen. Combining noble metal-based catalysts with these green oxidants represents an emerging sustainable alternative. In this regard, platinum-based catalysts exhibit good activity for alcohol oxidation in aqueous phases, along with environmentally friendly features such as mild reaction temperatures, water as a solvent, and molecular oxygen as an oxidant.

[0005] However, the large-scale application of platinum-based catalysts still faces several challenges, including catalyst deactivation, platinum particle agglomeration, and loss. The Journal of Catalysis (2014), Vol. 311, pp. 295-305, "On the deactivation of supported platinum catalysts for the selective oxidation of alcohols," reported on platinum catalysts used in the oxidation of various alcohols. The study found that the initial reaction rate of the catalysts decreased significantly as the reaction proceeded, indicating a significant deactivation phenomenon. Modulating the electronic structure and surface geometry of platinum metal by doping with a suitable second metal and selecting specific combinations can not only improve this phenomenon to a certain extent, but also enhance the activity and stability of platinum-based catalysts.

[0006] Patent publication number CN107570185B discloses a catalyst preparation method and application, belonging to the field of material preparation. The methods include: 1. Preparation of Fe₃O₄; 2. Preparation of HAP@Fe₃O₄; 3. Preparation of Au@Pt; 4. Preparation of the Au@Pt / HAP@Fe₃O₄ catalyst; and 5. Catalytic conversion of 1,2-propylene glycol to lactic acid. The present invention prepares a hydroxyapatite@ferroferric oxide-supported gold@platinum catalyst using a sol-sol immobilization method and uses it to catalyze the conversion of 1,2-propylene glycol to lactic acid at ambient pressure. This catalyst requires minimal dosage, produces lactic acid with high activity and selectivity at ambient pressure, and has a long catalytic life. However, the catalyst preparation method is complex, and the reaction system requires the addition of an external base, which can corrode the equipment and hinder product separation.

[0007] Therefore, it is of great significance to find a simple and easy method to prepare a highly active and highly selective catalyst for the oxidation of alcohols, which can achieve high conversion of alcohols to the corresponding carboxylic acids without adding external base.

[0008] Summary of the Invention

[0009] In view of the above-mentioned deficiencies in the prior art, the present invention provides an Au@Pt core-shell structure supported catalyst, which has a gold core-platinum shell structure and a small particle size, has high catalytic activity and good stability, and can achieve high conversion rate oxidation of alcohols without adding external base.

[0010] An Au@Pt core-shell structure supported catalyst comprises a carrier and Au@Pt nanoparticles supported on the carrier. The Au@Pt nanoparticles present a core-shell structure, wherein the core layer is Au and the shell layer is Pt. The Au@Pt nanoparticles have a particle size of 2-10 nm, the diameter of the core layer is 1-3 nm, and the thickness of the shell layer is 1-7 nm.

[0011] The catalyst prepared by the present invention has a gold core-platinum shell structure. Electron transfer occurs from the gold core inside the catalyst particles to the outer platinum layer, resulting in an electron-rich state on the platinum surface. This facilitates the occurrence of β-H elimination, the rate-determining step in alcohol oxidation. Simultaneously, the negatively valenced platinum reduces oxygen adsorption, improves poisoning, balances the adsorption strength of oxygen and substrate, promotes the reaction, and achieves excellent catalytic activity. Furthermore, the small particle size of the catalyst particles improves the dispersion of platinum on the catalyst surface, providing more reactive sites and further enhancing the catalyst's catalytic performance.

[0012] Preferably, the particle size distribution of the Au@Pt nanoparticles is as follows: the proportion of particles with a particle size of less than 3.25 nm is 0-20%, the proportion of particles with a particle size of 3.25 nm ≤ ≤ 6.25 nm is 46-78%, and the proportion of particles with a particle size of 6.25 nm < 10 nm is 1.5-54%.

[0013] Preferably, the carrier is at least one of TiO2, Al2O3, ZrO2, SiO2, CeO2, ZnO, MgO, Fe2O3 or carbon material.

[0014] Preferably, the mass ratio of the sum of Au and Pt in the Au@Pt core-shell structure supported catalyst to the carrier is 0.5-10:100.

[0015] The present invention also provides a method for preparing an Au@Pt core-shell structure supported catalyst. The method is simple in process and does not require a template in the preparation process. The Au@Pt core-shell structure supported catalyst for alcohol oxidation can be prepared only by liquid-phase reduction at room temperature.

[0016] A method for preparing an Au@Pt core-shell structure supported catalyst comprises the following steps:

[0017] (1) dispersing a gold source in a solvent to obtain a gold source solution, adding a surfactant to the gold source solution and dissolving the gold source solution to obtain a mixed solution;

[0018] (2) adding a reducing substance to the mixed solution obtained in step (1) to react to obtain a mixed solution in which gold particles are dispersed;

[0019] (3) adding a platinum source to the mixed solution obtained in step (2), and then adding a reducing substance to react to obtain a mixed solution in which gold core-platinum shell nanoparticles are dispersed;

[0020] (4) adding a carrier to the mixed solution in which the gold core-platinum shell nanoparticles are dispersed obtained in step (3), adjusting the pH value of the mixed solution to not higher than the isoelectric point of the carrier and stirring, washing, separating, and drying to obtain an Au@Pt core-shell structure supported catalyst.

[0021] The present invention prepares an Au@Pt core-shell structure supported catalyst by the above-mentioned method. The gold source is dispersed in the solution to reduce the gold source concentration, thereby preventing excessively large reduced particles due to local excessive concentration. A reducing substance is added to the solution to reduce the gold source and precipitate it into gold particles. Since the surfactant is coated on the surface of the gold particles, the growth and aggregation of the gold particles can be prevented. After adding the platinum source and the reducing substance, the platinum is deposited on the surface with the gold as the core, gradually maturing and growing into particles with a gold core and platinum shell structure. A carrier is added and the pH is adjusted to be no higher than its isoelectric point, and the particles are loaded on the carrier through electrostatic interaction. Finally, the Au@Pt core-shell structure catalyst is obtained after filtration, washing, separation, and drying.

[0022] Preferably, in step (1), the gold source is at least one of chloroauric acid, gold nitrate, triphenylphosphine gold or ferrocene gold nitrate.

[0023] Preferably, in step (1), the solvent is at least one of water, ethanol, methanol, acetone, dimethylformamide, dimethyl sulfoxide or ethyl acetate.

[0024] Preferably, in step (1), the concentration of the gold source solution is 1-40 mg / mL.

[0025] Preferably, in step (1), the surfactant is at least one of sodium lauryl sulfate, sodium octyl sulfonate, sodium dodecylbenzene sulfonate, polyacrylonitrile, polyvinyl pyrrolidone, polyvinyl butyral or polyvinyl alcohol.

[0026] Preferably, in step (1), the molar ratio of the gold source to the surfactant is 0.1-10:1.

[0027] Preferably, in step (2), the ratio of the mass of the gold particles in the mixed solution dispersed with the gold particles to the volume of the mixed solution is 0.01-0.4 mg / mL.

[0028] Preferably, in step (3), the platinum source is at least one of chloroplatinic acid, platinic acid, platinum trichloride or platinum nitrate.

[0029] Preferably, the molar ratio of the gold source to the platinum source is 0.01-99:1.

[0030] Preferably, in step (3), the ratio of the mass of the gold core-platinum shell nanoparticles in the mixed solution dispersed with the gold core-platinum shell nanoparticles to the volume of the mixed solution is 0.02-0.8 mg / mL.

[0031] Preferably, in step (2) and step (3), the reducing substance is at least one of hydrogen, sodium borohydride, hydrazine hydrate, ethanol or acetone.

[0032] Preferably, in step (2), the molar ratio of the gold source to the reducing substance is 0.1-5:1.

[0033] Preferably, in step (3), the molar ratio of the platinum source to the reducing substance is 0.1-5:1.

[0034] The present invention also provides the use of the Au@Pt core-shell supported catalyst in alcohol oxidation reactions. The Au@Pt core-shell supported catalyst can achieve high conversion rates of alcohols to produce the corresponding carboxylic acids without adding an external base to the reaction system, resulting in a green and efficient reaction process.

[0035] Preferably, when the Au@Pt core-shell structure supported catalyst is used for the alcohol oxidation reaction, the alcohol substrate and the Au@Pt core-shell structure supported catalyst are added to the reaction system, and the reaction is carried out at a reaction temperature of 30-150°C and an oxygen pressure of 0.1-2.0 MPa for 1-48 hours to prepare the corresponding acid substance.

[0036] Preferably, the alcohol substrate includes aliphatic alcohol, aromatic alcohol, monohydric alcohol or dihydric alcohol.

[0037] Preferably, the molar ratio of the alcohol substrate to the Au@Pt core-shell structure supported catalyst is 10-500:1.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] (1) The method of the present invention does not require the use of a template agent and can prepare the Au@Pt core-shell structure supported catalyst only by liquid-phase reduction at room temperature. The process is simple and convenient.

[0040] (2) The catalyst prepared by the method of the present invention has a unique core-shell structure, which can enhance the electron transfer effect between gold and platinum, reduce the adsorption strength of oxygen, and improve the poisoning phenomenon of oxygen on platinum metal alone. Compared with pure platinum-based catalysts, the catalyst of the present invention has better catalytic activity and stability.

[0041] (3) When the catalyst of the present invention is used in the oxidation reaction of alcohols, the reaction system can achieve high conversion rate oxidation of alcohols to obtain corresponding carboxylic acids without adding external alkali, thereby reducing the corrosion of alkali solution on equipment and avoiding the problem that the product exists in the form of free salt and is difficult to separate.

[0042] (4) The catalyst substrate of the present invention has a wide range of applications and can be used for the catalytic oxidation of most alcohol substances. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 is a morphological and structural characteristic diagram of the Au@Pt / CeO2 catalyst prepared in Example 1, wherein Figure 1(A) is a transmission electron microscope image with a scale of 50 nm; Figure 1(B) is a local enlarged view of Figure 1(A); and Figure 1(C) is an EDS line scan image at the dotted position of Figure 1(B).

[0044] FIG2 is a statistical particle size distribution diagram of the Au@Pt / CeO2 catalyst prepared in Example 1.

[0045] FIG3 is a graph showing ultraviolet absorption spectra of the Au@Pt / CeO2 catalyst prepared in Example 1 and the Au particles prepared in Comparative Example 1.

[0046] FIG4 is an XPS spectrum of the Au@Pt / CeO2 catalyst prepared in Example 1 and the Pt / CeO2 catalyst prepared in Comparative Example 2.

[0047] FIG5 is a CO-FTIR spectrum of the Au@Pt / CeO2 catalyst prepared in Example 1 and the Pt / CeO2 catalyst prepared in Comparative Example 2. DETAILED DESCRIPTION

[0048] The present invention will be further described in detail below with reference to the examples, but the embodiments of the present invention are not limited thereto. The experimental methods in the following examples are conventional methods unless otherwise specified. The experimental materials used in the following examples were purchased from a conventional biochemical reagent platform unless otherwise specified.

[0049] In the examples, high performance liquid chromatography was used to perform qualitative and quantitative analysis on the reactants and products.

[0050] The conversion rate of alcohols C was calculated by normalization method according to the following formula: Alcohol , acid selectivity S Acid and yield Y Acid .

[0051] The results in the following examples are the average values ​​of 3 repetitions.

[0052] Example 1: Au and Pt loaded on CeO2 by sodium borohydride and hydrogen respectively

[0053] Solution A: aqueous solution of HAuCl4, with a mass concentration of Au of 10 mg / mL;

[0054] Solution B: aqueous solution of PVA, with a mass fraction of PVA of 0.5 wt%;

[0055] Solution C: NaBH4 aqueous solution, the molar concentration of NaBH4 is 0.1M;

[0056] Solution D: aqueous solution of H2PtCl6, with a Pt concentration of 10 mg / mL;

[0057] 0.5 mL of solution A and 1 mL of solution B were added to 100 mL of deionized water, stirred for 1 hour, and then 5 mL of solution C was added dropwise. After stirring for 2 hours, 0.5 mL of solution D was added. After stirring for 2 hours, hydrogen was bubbled for 2 hours. The mixture was sealed and allowed to stand for 48 hours. After adding 1 g of CeO2 carrier, nitric acid was added dropwise to adjust the pH to 2 and stirred vigorously. The mixture was filtered and washed with deionized water until there was no Cl in the filtrate. - The Au@Pt / CeO2 catalyst was obtained by drying at 50 °C for 6 h.

[0058] The morphological structure characteristics of the Au@Pt / CeO2 catalyst prepared in this example are shown in Figure 1. In Figure 1(a), spherical particles are evenly distributed on the sheet-like carrier CeO2. Figure 1(b) is an enlarged view of a selected location in Figure 1(a). The lattice fringes of the particles are clearly visible, with a spacing of 0.23 nm, which is consistent with the interplanar spacing of Pt(111). Figure 1(c) is an EDS line scan at the dotted position in Figure 1(b). The solid line and dotted line represent the signal intensities of gold and platinum, respectively. The gold signal width is narrow and concentrated in the middle area, while the platinum signal is wide and high at both ends and low in the middle, indicating that the catalyst structure is a gold core platinum shell structure.

[0059] Figure 2 is a statistical average particle size distribution diagram of the Au@Pt / CeO2 catalyst prepared in this embodiment. As shown in Figure 2, the average particle size of the catalyst prepared in this embodiment is 4.27nm. Figure 3 is a UV absorption spectrum of the Au@Pt / CeO2 catalyst particles prepared in this embodiment and the Au particles prepared in Comparative Example 1. As shown in Figure 3, the gold nanoparticles exhibit a unique UV absorption peak at 520nm, while the gold core platinum shell nanoparticles have almost no absorption intensity at 520nm, further indicating that the internal gold particles are wrapped by the platinum shell layer.

[0060] Example 2: Loading Au and Pt on CeO2 via sodium borohydride

[0061] Solution A: aqueous solution of HAuCl4, with a mass concentration of Au of 10 mg / mL;

[0062] Solution B: aqueous solution of PVA, with a mass fraction of PVA of 0.5 wt%;

[0063] Solution C: NaBH4 aqueous solution, the molar concentration of NaBH4 is 0.1M;

[0064] Solution D: aqueous solution of H2PtCl6, with a Pt concentration of 10 mg / mL;

[0065] 0.5 mL of solution A and 1 mL of solution B were added to 100 mL of deionized water. After stirring for 1 hour, 5 mL of solution C was added dropwise. After stirring for 2 hours, 0.5 mL of solution D was added. After continuing to stir for 2 hours, 5 mL of solution C was added dropwise. The mixture was sealed and allowed to stand for 48 hours. After adding 1 g of CeO2 carrier, nitric acid was added dropwise to adjust the pH to 2 and stirred vigorously. The mixture was filtered and washed with deionized water until there was no Cl in the filtrate. - The Au@Pt / CeO2 catalyst was obtained by drying at 50°C for 6 hours. The average particle size of the catalyst prepared in this embodiment was 6.78 nm.

[0066] Comparative Example 1: Au loaded on CeO2 by sodium borohydride liquid phase reduction

[0067] Solution A: aqueous solution of HAuCl4, with a mass concentration of Au of 10 mg / mL;

[0068] Solution B: PVA aqueous solution, PVA mass fraction is 0.5%;

[0069] Solution C: NaBH4 aqueous solution, the molar concentration of NaBH4 is 0.1M;

[0070] 1 mL of solution A and 1 mL of solution B were added to 100 mL of deionized water, stirred for 1 hour, and then 5 mL of solution C was added dropwise. The mixture was sealed and allowed to stand for 48 hours. Then 1 g of CeO2 carrier was added. Nitric acid was added dropwise to adjust the pH to 2 and stirred vigorously. The mixture was filtered and washed with deionized water until there was no Cl in the filtrate. - The Au / CeO2 catalyst was obtained by drying at 50°C for 6 h.

[0071] Comparative Example 2: Pt loaded on CeO2 by hydrogen liquid phase reduction

[0072] Solution A: aqueous solution of H2PtCl6, with a Pt concentration of 10 mg / mL;

[0073] Solution B: PVA aqueous solution, PVA mass fraction is 0.5%;

[0074] Solution C: NaBH4 aqueous solution, the molar concentration of NaBH4 is 0.1M;

[0075] 1 mL of solution A and 1 mL of solution B were added to 100 mL of deionized water, stirred for 1 hour, bubbled with hydrogen for 2 hours, and allowed to stand in a sealed container for 48 hours. 1 g of CeO2 carrier was then added, nitric acid was added dropwise to adjust the pH to 2, and stirred vigorously. The filtrate was filtered and washed with deionized water until there was no Cl in the filtrate. - The catalyst was detected and dried at 50 °C for 6 h to obtain Pt / CeO2 catalyst.

[0076] The electronic structure and geometric structure comparison of the Pt / CeO2 catalyst prepared in this comparative example and the Au@Pt / CeO2 catalyst prepared in Example 1 are shown in Figures 4-5. As shown in Figure 4, the Pt 4f 7 / 2 Compared to monometallic Pt / CeO2, the position of the Au@Pt / CeO2 structure shifts significantly toward a lower binding energy position, indicating that electron transfer occurs from the Au core to the Pt shell in the Au@Pt / CeO2 structure, making the valence state of the surface Pt atoms more negative. As shown in Figure 5, the CO absorption peak of the core-shell structure Au@Pt / CeO2 has almost no significant change compared to monometallic Pt / CeO2, indicating that the surface geometry of Au@Pt / CeO2 has hardly changed compared to Pt / CeO2.

[0077] Test example

[0078] The catalytic effects of the catalysts prepared in Examples 1-2 and Comparative Examples 1-2 were compared using tetrahydrofurfuryl alcohol as the reaction substrate. Reaction conditions: 0.15 g of each catalyst prepared in Example 1-2 and Comparative Example 1-2 was added to 30 mL of water at a 0.01 M tetrahydrofurfuryl alcohol concentration. The reaction was maintained at an oxygen pressure of 0.1 MPa and a temperature of 100°C for 3 hours.

[0079] The tetrahydrofurfuryl alcohol conversion and tetrahydrofuroic acid yield obtained in this test example are shown in Table 1. As shown in Table 1, the gold catalyst alone has little activity for alcohol oxidation in the absence of an added base. Compared to the platinum catalyst Pt / CeO2 alone, the Au@Pt / CeO2 catalyst prepared in the present invention significantly improves the tetrahydrofurfuryl alcohol conversion and tetrahydrofuroic acid yield, and the catalytic performance is even better when the catalyst particle size is smaller.

[0080] Table 1 Catalytic effect of the catalysts prepared in Examples 1-2 and Comparative Examples 1-2 in the oxidation reaction of tetrahydrofurfuryl alcohol

[0081] Catalyst performance evaluation

[0082] Comparison of Catalytic Systems: The Au@Pt / CeO2 catalyst prepared in Example 1 was compared with existing alcohol oxidation catalysts in the catalytic reaction of tetrahydrofurfuryl alcohol. The results are shown in Table 2. As shown in Table 2, the reaction conditions of the catalytic system involved in the Au@Pt / CeO2 catalyst prepared in this example are milder than those of existing alcohol catalysts, allowing for the reaction to proceed at lower temperatures and pressures. Both the tetrahydrofurfuryl alcohol conversion rate and the yield of tetrahydrofurfurylic acid were higher. Furthermore, the Au@Pt / CeO2 catalyst prepared in Example 1 can oxidize alcohols to the corresponding carboxylic acids without the addition of an alkali solution, reducing alkali corrosion on the equipment and avoiding the problem of the product being difficult to separate as a free salt.

[0083] Table 2 Comparison of the catalytic system of Au@Pt / CeO2 catalyst prepared in Example 1 and existing catalysts

[0084] Au@Pt / CeO2 catalyst improves oxygen poisoning phenomenon: Generally speaking, a negative reaction order indicates that the substance is too strongly adsorbed on the active site to saturation, and even has a poisoning effect on the reaction. The changes in the reaction order of the Au@Pt / CeO2 catalyst prepared in Example 1 and the Pt / CeO2 catalyst prepared in Comparative Example 2 in the catalytic oxidation reaction of tetrahydrofurfuryl alcohol are shown in Table 3. As can be seen from Table 3, the oxygen order of the core-shell structure Au@Pt / CeO2 is 0, while the reaction order of Pt / CeO2 is -0.8. This shows that the Au@Pt / CeO2 catalyst reduces the adsorption intensity of oxygen and improves the poisoning phenomenon of oxygen on the single platinum metal. This is mainly due to the electron transfer from the gold core inside the catalyst particle to the external platinum layer, resulting in the platinum surface being electron-rich. The single platinum particle adsorbs oxygen too strongly to cause poisoning phenomenon, while the negative valence platinum can weaken the adsorption of oxygen and improve the poisoning phenomenon, while balancing the adsorption intensity of oxygen and substrate.

[0085] Table 3 Substrate order and oxygen order of the catalysts prepared in Example 1 and Comparative Example 2

[0086] The reaction activity of Au@Pt / CeO2 catalyst changes with reaction time: the reaction conditions are as follows: the concentration of tetrahydrofurfuryl alcohol is 0.01 M in 30 mL of water system, 0.15 g of the catalyst prepared in Example 1 is added, the oxygen pressure is maintained at 0.1 MPa, the temperature is 100°C, and the reaction time is changed.

[0087] Table 4 shows the changes in reactant conversion and product yield over reaction time in the catalytic oxidation reaction of tetrahydrofurfuryl alcohol using the catalyst prepared in Example 1. As shown in Table 4, both the conversion of tetrahydrofurfuryl alcohol and the yield of tetrahydrofurfurylic acid continue to increase with increasing reaction time. Complete conversion of the substrate and a 92% yield of tetrahydrofurfurylic acid are achieved at 3 h.

[0088] Table 4 Changes in the reaction activity of the Au@Pt / CeO2 catalyst prepared in Example 1 with reaction time

[0089] The reactivity of the Au@Pt / CeO2 catalyst varied with oxygen pressure. The reaction conditions were: a 0.01 M tetrahydrofurfuryl alcohol concentration in 30 mL of water, 0.15 g of the catalyst prepared in Example 1, varying the oxygen pressure, and a temperature of 100°C for 3 hours. The reaction results are shown in Table 5.

[0090] As shown in Table 5, when the oxygen pressure is changed within a certain range, the conversion rate of tetrahydrofurfuryl alcohol and the yield of tetrahydrofurfurylic acid hardly change.

[0091] The reaction activity of Au@Pt / CeO2 catalyst changes with reaction temperature: the reaction conditions are as follows: the concentration of tetrahydrofurfuryl alcohol is 0.01 M in 30 mL of water system, 0.15 g of the catalyst prepared in Example 1 is added, the oxygen pressure is maintained at 0.1 MPa, the temperature is changed, and the reaction is carried out for 3 hours.

[0092] Table 5 Variation of the reaction activity of Au@Pt / CeO2 catalyst prepared in Example 1 with oxygen pressure

[0093] The reaction results are shown in Table 6. As can be seen from Table 6, as the reaction temperature increases, the conversion rate of tetrahydrofurfuryl alcohol and the yield of tetrahydrofurfurylic acid continue to increase. After the temperature rises to 100°C, the conversion rate and yield reach the highest point and remain almost unchanged.

[0094] Table 6 Variation of the reaction activity of the Au@Pt / CeO2 catalyst prepared in Example 1 with the reaction temperature

[0095] Cyclic stability testing of the Au@Pt / CeO2 catalyst was performed using a 0.01 M tetrahydrofurfuryl alcohol (THF) concentration in 30 mL of water. 0.075 g of the catalyst prepared in Example 1 was added, and the reaction temperature was maintained at 90°C for 3 h. After the reaction, the catalyst was filtered, washed, dried, and then recycled. The same process was repeated. The reaction results are shown in Table 7.

[0096] As shown in Table 7, after the catalyst was recycled for multiple times, the conversion rate of tetrahydrofurfuryl alcohol and the yield of tetrahydrofurfurylic acid had almost no significant changes, indicating that the catalyst prepared by this method had good stability.

[0097] Substrate compatibility of the Au@Pt / CeO2 catalyst: To demonstrate the catalyst's compatibility for the oxidation of various alcohol substrates, representative alcohols, including aliphatic, aromatic, short-chain, long-chain, linear, cyclic, monohydric, and dihydric alcohols, were selected as substrates. The reaction conditions were: a substrate concentration of 0.01 M in 30 mL of water, 0.075 g of the catalyst prepared in Example 1, an oxygen pressure of 0.1 MPa, and a temperature of 90°C for 3 h.

[0098] Table 7 Cyclic stability test results of Au@Pt / CeO2 catalyst prepared in Example 1

[0099] The reaction results are shown in Table 8. The overall catalytic activity is aromatic > aliphatic, short chain > long chain, linear > cyclic, monohydric alcohol > dihydric alcohol. This is due to the difference in oxidation activity caused by the electronic structure and steric hindrance of the functional groups adjacent to the hydroxyl group in the substrate.

[0100] Table 8 Conversion rate of different reaction substrates and target product yield of Au@Pt / CeO2 catalyst prepared in Example 1

Claims

1. An Au@Pt core-shell structure supported catalyst, comprising a carrier and Au@Pt nanoparticles supported on the carrier, characterized in that: The Au@Pt nanoparticles have a core-shell structure, wherein the core layer is Au and the shell layer is Pt. The particle size of the Au@Pt nanoparticles is 2-10 nm, the diameter of the core layer is 1-3 nm, and the thickness of the shell layer is 1-7 nm.

2. The Au@Pt core-shell structure supported catalyst according to claim 1, characterized in that: The particle size distribution of the Au@Pt nanoparticles is as follows: the proportion of particles with a particle size of less than 3.25 nm is 0-20%, the proportion of particles with a particle size of 3.25 nm≤particle size≤6.25 nm is 46-78%, and the proportion of particles with a particle size of 6.25 nm<particle size<10 nm is 1.5-54%.

3. The Au@Pt core-shell structure supported catalyst according to claim 1, characterized in that: The carrier is at least one of TiO2, Al2O3, ZrO2, SiO2, CeO2, ZnO, MgO, Fe2O3 or carbon materials, and the mass ratio of the sum of Au and Pt in the Au@Pt core-shell structure supported catalyst to the carrier is 0.5-10:

100.

4. The method for preparing the Au@Pt core-shell structure supported catalyst according to any one of claims 1 to 3, characterized in that: The following steps are involved: (1) dispersing a gold source in a solvent to obtain a gold source solution, and adding a surfactant to the gold source solution to dissolve the gold source solution to obtain a mixed solution; (2) adding a reducing substance to the mixed solution obtained in step (1) to react to obtain a mixed solution in which gold particles are dispersed; (3) adding a platinum source to the mixed solution obtained in step (2), and then adding a reducing substance to react to obtain a mixed solution in which gold core-platinum shell nanoparticles are dispersed; (4) adding a carrier to the mixed solution in which the gold core-platinum shell nanoparticles are dispersed obtained in step (3), adjusting the pH value of the mixed solution to not higher than the isoelectric point of the carrier and stirring, washing, separating, and drying to obtain an Au@Pt core-shell structure supported catalyst.

5. The preparation method according to claim 4, characterized in that: In step (1), the gold source is at least one of chloroauric acid, gold nitrate, triphenylphosphine gold or ferrocene gold acid, the solvent is at least one of water, ethanol, methanol, acetone, dimethylformamide, dimethyl sulfoxide or ethyl acetate, and the concentration of the gold source solution is 1-40 mg / mL.

6. The preparation method according to claim 5, characterized in that: In step (1), the surfactant is at least one of sodium dodecyl sulfate, sodium octyl sulfonate, sodium dodecylbenzene sulfonate, polyacrylonitrile, polyvinyl pyrrolidone, polyvinyl butyral or polyvinyl alcohol, and the molar ratio of the gold source to the surfactant is 0.1-10:

1.

7. The preparation method according to claim 4, characterized in that: In step (3), the platinum source is at least one of chloroplatinic acid, platinic acid, platinum trichloride or platinum nitrate, and the molar ratio of the gold source to the platinum source is 0.01-99:

1.

8. The preparation method according to claim 4, characterized in that: In step (2) and step (3), the reducing substance is at least one of hydrogen, sodium borohydride, hydrazine hydrate, ethanol or acetone, the molar ratio of the gold source to the reducing substance is 0.1-5:1, and the molar ratio of the platinum source to the reducing substance is 0.1-5:

1.

9. Use of the Au@Pt core-shell structure supported catalyst according to any one of claims 1 to 3 in the oxidation reaction of alcohols.

10. The use of the Au@Pt core-shell structure supported catalyst in alcohol oxidation reaction according to claim 9, characterized in that: The reaction conditions of the Au@Pt core-shell structure supported catalyst for alcohol oxidation reaction are: reaction temperature of 30-150° C. and oxygen pressure of 0.1-2.0 MPa for 1-48 hours.

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