Au@Pt core-shell structure supported catalyst, and preparation method and application thereof

Abstract

The application discloses an Au@Pt core-shell structure supported catalyst, which comprises a carrier and Au@Pt nanoparticles supported on the carrier, the Au@Pt nanoparticles are in a core-shell structure, wherein the core layer is Au, 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. The application further discloses a preparation method of the Au@Pt core-shell structure supported catalyst and application of the catalyst in an alcohol oxidation process. According to the method, the alcohol oxidation catalyst can be prepared only through room-temperature liquid-phase reduction, the process is simple and convenient, the prepared catalyst has a unique core-shell structure, and the catalyst has excellent catalytic activity and stability, so that the reaction system can realize high conversion rate oxidation of alcohol to obtain corresponding carboxylic acid without adding an external alkali.

Description

Technical Field

[0001] This invention belongs to the field of industrial catalysis, specifically relating to an Au@Pt core-shell structure supported catalyst, its preparation method, and its application. Background Technology

[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 plastics, detergents, paints, cosmetics, food additives and pharmaceutical intermediates.

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

[0004] Various catalytic methods 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 forms an emerging sustainable alternative. In this regard, platinum-based catalysts exhibit good activity and environmentally friendly characteristics in the oxidation of alcohols in the aqueous phase, such as mild reaction temperature, water as solvent, and molecular oxygen as 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 *Journal of Catalysis* (2014), Vol. 311, pp. 295-305, in its article "On the deactivation of supported platinum catalysts for selective oxidation of alcohols," applied platinum catalysts to the oxidation reactions of various alcohols and found that the initial reaction rate of the catalyst decreased significantly as the reaction proceeded, indicating significant deactivation. Doping with a suitable second metal and selecting specific combinations to modulate the electronic structure and surface geometry of platinum can not only improve this phenomenon to some extent but also enhance the activity and stability of platinum-based catalysts.

[0006] Patent document CN107570185B discloses a method for preparing a catalyst and its application, belonging to the field of materials preparation, including: 1. Preparation of Fe3O4; 2. Preparation of HAP@Fe3O4; 3. Preparation of Au@Pt; 4. Preparation of the catalyst Au@Pt / HAP@Fe3O4; 5. Catalysis of 1,2-propanediol to lactic acid. This invention prepares a hydroxyapatite@ferric oxide supported gold@platinum catalyst via a sol-gel immobilization method and uses it to catalyze the preparation of 1,2-propanediol to lactic acid under normal pressure. This catalyst requires a small amount, can produce lactic acid with high activity and high selectivity under normal pressure, and has a good catalytic lifetime. However, the catalyst preparation method is complex, and the reaction system requires the addition of an external alkali, which can lead to equipment corrosion and difficulties in product separation.

[0007] Therefore, it is of great significance to find a simple and easy method to prepare a catalyst with high activity and high selectivity for alcohol oxidation, and to achieve high conversion of alcohols to the corresponding carboxylic acids without the addition of an external base. Summary of the Invention

[0008] In view of the shortcomings of the prior art, the present invention provides an Au@Pt core-shell supported catalyst. This catalyst has a gold core and platinum shell structure and a small particle size, exhibiting high catalytic activity and good stability, and can achieve high conversion oxidation of alcohols without the addition of external alkali.

[0009] An Au@Pt core-shell supported catalyst includes a support and Au@Pt nanoparticles supported on the support. 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.

[0010] The catalyst prepared in this invention has a gold core-platinum shell structure. Electron transfer occurs from the gold core inside the catalyst particle to the outer platinum layer, resulting in an electron-rich state on the platinum surface. This is beneficial for the rate-determining step—β-H elimination—in alcohol oxidation. Simultaneously, the negatively valent platinum weakens oxygen adsorption, improving poisoning and balancing the adsorption strength of oxygen and substrate, thus promoting the reaction and achieving excellent catalytic activity. Furthermore, the small particle size of the catalyst increases the dispersion of platinum on the catalyst surface, providing more reactive sites and further enhancing the catalytic performance.

[0011] Preferably, the particle size distribution of the Au@Pt nanoparticles is as follows: the proportion of particles with a diameter < 3.25 nm is 0-20%, the proportion of particles with a diameter 3.25 nm ≤ 6.25 nm is 46-78%, and the proportion of particles with a diameter 6.25 nm < 10 nm is 1.5-54%.

[0012] Preferably, the carrier is at least one of TiO2, Al2O3, ZrO2, SiO2, CeO2, ZnO, MgO, Fe2O3, or carbon materials.

[0013] Preferably, the mass ratio of the sum of Au and Pt to the support in the Au@Pt core-shell supported catalyst is 0.5-10:100.

[0014] This invention also provides a method for preparing Au@Pt core-shell structured supported catalysts. This method is simple, requires no template agent, and can prepare Au@Pt core-shell structured supported catalysts for alcohol oxidation simply by room temperature liquid-phase reduction.

[0015] A method for preparing an Au@Pt core-shell supported catalyst includes the following steps:

[0016] (1) Disperse the gold source in a solvent to obtain a gold source solution, add a surfactant to the gold source solution, and dissolve to obtain a mixed solution;

[0017] (2) Add a reducing agent to the mixed solution obtained in step (1) to react and obtain a mixed solution with gold particles dispersed in it.

[0018] (3) Add a platinum source to the mixed solution obtained in step (2), and then add a reducing substance to react and obtain a mixed solution with gold core platinum shell nanoparticles dispersed in it.

[0019] (4) Add a support to the mixed solution containing gold core and platinum shell nanoparticles obtained in step (3), adjust the pH value of the mixed solution to be no higher than the isoelectric point of the support and stir, wash, separate and dry to obtain Au@Pt core-shell structure supported catalyst.

[0020] This invention prepares an Au@Pt core-shell supported catalyst using the above method. Dispersing the gold source in solution reduces its concentration, preventing excessively large reduced particles due to localized high concentrations. Adding a reducing agent to the solution reduces the gold source, precipitating it as gold particles. The surfactant coating on the surface prevents the gold particles from growing and agglomerating. Adding a platinum source and reducing agent causes platinum to deposit on the gold core, gradually maturing and growing into gold-core platinum-shell structured particles. A support is added, and the pH is adjusted to not exceed the isoelectric point, allowing the particles to be electrostatically loaded onto the support. Finally, the catalyst is filtered, washed, separated, and dried to obtain the Au@Pt core-shell catalyst.

[0021] Preferably, in step (1), the gold source is at least one of chloroauric acid, gold nitrate, triphenylphosphine gold, or ferrocene gold.

[0022] Preferably, in step (1), the solvent is at least one of water, ethanol, methanol, acetone, dimethylformamide, dimethyl sulfoxide, or ethyl acetate.

[0023] Preferably, in step (1), the concentration of the gold source solution is 1-40 mg / mL.

[0024] Preferably, in step (1), the surfactant is at least one of sodium dodecyl sulfate, sodium octyl sulfonate, sodium dodecylbenzene sulfonate, polyacrylonitrile, polyvinylpyrrolidone, polyvinyl butyral, or polyvinyl alcohol.

[0025] Preferably, in step (1), the molar ratio of the gold source to the surfactant is 0.1-10:1.

[0026] Preferably, in step (2), the mass ratio of gold particles to the volume of the mixed solution in which gold particles are dispersed is 0.01-0.4 mg / mL.

[0027] Preferably, in step (3), the platinum source is at least one of chloroplatinic acid, platinic acid, platinum trichloride, or platinum nitrate.

[0028] Preferably, the molar ratio of the gold source to the platinum source is 0.01-99:1.

[0029] Preferably, in step (3), the mass ratio of the gold core platinum shell nanoparticles to the volume of the mixed solution in the dispersed gold core platinum shell nanoparticle mixed solution is 0.02-0.8 mg / mL.

[0030] Preferably, in steps (2) and (3), the reducing substance is at least one of hydrogen, sodium borohydride, hydrazine hydrate, ethanol, or acetone.

[0031] Preferably, in step (2), the molar ratio of the gold source to the reducing substance is 0.1-5:1.

[0032] Preferably, in step (3), the molar ratio of the platinum source to the reducing substance is 0.1-5:1.

[0033] This invention also provides the application of the Au@Pt core-shell structured supported catalyst in alcohol oxidation reactions. The Au@Pt core-shell structured supported catalyst of this invention can achieve high-conversion oxidation of alcohols to the corresponding carboxylic acids without the addition of an external alkali to the reaction system, and the reaction process is green and efficient.

[0034] Preferably, when the Au@Pt core-shell supported catalyst is used for alcohol oxidation reaction, an alcohol substrate and the Au@Pt core-shell supported catalyst are added to the reaction system, and the reaction is carried out at a reaction temperature of 30-150℃ and an oxygen pressure of 0.1-2.0MPa for 1-48 hours to prepare the corresponding acidic substance.

[0035] Preferably, the alcohol substrate includes aliphatic alcohols, aromatic alcohols, monohydric alcohols, or dihydric alcohols.

[0036] Preferably, the molar ratio of the alcohol substrate to the Au@Pt core-shell supported catalyst is 10-500:1.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] (1) The method of the present invention does not require the use of a template agent. Au@Pt core-shell structured supported catalyst can be prepared by room temperature liquid phase reduction. The process is simple and convenient.

[0039] (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 intensity of oxygen, and improve the poisoning phenomenon of oxygen on platinum metal alone. Compared with simple platinum-based catalysts, the catalyst of the present invention has better catalytic activity and stability.

[0040] (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 the corresponding carboxylic acids without the addition of external alkali, which reduces the corrosion of equipment by alkali solution and avoids the problem that the product exists in the form of free salt and is difficult to separate.

[0041] (4) The catalyst substrate of the present invention has a wide range of applications and can be used for the catalytic oxidation of most alcohols. Attached Figure Description

[0042] Figure 1 The image shows the morphological and structural characteristics of the Au@Pt / CeO2 catalyst prepared in Example 1. Figure 1 (A) is a transmission electron microscope image at a scale bar of 50 nm; Figure 1 (B) is Figure 1 (A) is a magnified view of a portion of the image. Figure 1 (C) is Figure 1 (B) EDS line scan at the dashed line position.

[0043] Figure 2 The statistical particle size distribution diagram is shown for the Au@Pt / CeO2 catalyst prepared in Example 1.

[0044] Figure 3The UV absorption spectra of the Au@Pt / CeO2 catalyst prepared in Example 1 and the Au particles prepared in Comparative Example 1 are shown.

[0045] Figure 4 XPS spectra of the Au@Pt / CeO2 catalyst prepared in Example 1 and the Pt / CeO2 catalyst prepared in Comparative Example 2.

[0046] Figure 5 CO-FTIR spectra of the Au@Pt / CeO2 catalyst prepared in Example 1 and the Pt / CeO2 catalyst prepared in Comparative Example 2. Detailed Implementation

[0047] The present invention will be further described in detail below with reference to embodiments, but the embodiments of the present invention are not limited thereto. Unless otherwise specified, the experimental methods in the following embodiments are conventional methods. Unless otherwise specified, the experimental materials used in the following embodiments were purchased from conventional biochemical reagent platforms.

[0048] In the examples, high performance liquid chromatography was used for qualitative and quantitative analysis of the reactants and products.

[0049] The conversion rate C of alcohols was calculated using the normalization method according to the following formula. Alcohol Selectivity of acids Acid and yield Y Acid .

[0050]

[0051]

[0052]

[0053] The results in the following examples are the average of three replicates.

[0054] Example 1: Au and Pt were loaded onto CeO2 using sodium borohydride and hydrogen gas, respectively.

[0055] Solution A: An aqueous solution of HAuCl4, with a Au concentration of 10 mg / mL;

[0056] Solution B: An aqueous solution of PVA with a mass fraction of 0.5 wt%;

[0057] Solution C: An aqueous solution of NaBH4 with a molar concentration of 0.1 M;

[0058] Solution D: An aqueous solution of H2PtCl6, with a Pt mass concentration of 10 mg / mL;

[0059] Add 0.5 mL of solution A and 1 mL of solution B to 100 mL of deionized water and stir for 1 h. Then, add 5 mL of solution C dropwise and stir for 2 h. Add 0.5 mL of solution D and continue stirring for 2 h. Bubble with hydrogen gas for 2 h, then let stand in a sealed container for 48 h. Add 1 g of CeO2 carrier, then add nitric acid dropwise to adjust the pH to 2 while stirring vigorously. Filter and wash with deionized water until no Cl is found in the filtrate. - The catalyst was detected and dried at 50°C for 6 hours to obtain Au@Pt / CeO2 catalyst.

[0060] The morphological and structural characteristics of the Au@Pt / CeO2 catalyst prepared in this embodiment are shown in the figure below. Figure 1 As shown. In Figure 1 In (a), spherical particles are uniformly distributed on the sheet-like support CeO2. Figure 1 (b) for selection Figure 1 (a) shows a magnified image of a particle where the lattice fringes are clearly visible, measuring 0.23 nm, which matches the interplanar spacing of Pt(111). Figure 1 (c) is Figure 1 (b) Line scan of EDS at the dashed line position. The solid line and the dashed line represent the signal intensity of gold and platinum, respectively. The signal width of gold is narrower and concentrated in the middle region, while the signal of platinum is wider and higher at both ends and lower in the middle. This indicates that the catalyst structure is a gold core and platinum shell structure.

[0061] Figure 2 This is a statistically average particle size distribution diagram of the Au@Pt / CeO2 catalyst prepared in this embodiment. Figure 2 It can be seen that the average particle size of the catalyst prepared in this embodiment is 4.27 nm. Figure 3 The images show the UV absorption spectra of the Au@Pt / CeO2 catalyst particles prepared in this example and the Au particles prepared in Comparative Example 1. Figure 3 It can be seen that gold nanoparticles exhibit a unique ultraviolet absorption peak at 520 nm, while gold core platinum shell nanoparticles have almost no absorption intensity at 520 nm, further indicating that the internal gold particles are wrapped in a platinum shell.

[0062] Example 2: Loading Au and Pt onto CeO2 with sodium borohydride

[0063] Solution A: An aqueous solution of HAuCl4, with a Au concentration of 10 mg / mL;

[0064] Solution B: An aqueous solution of PVA with a mass fraction of 0.5 wt%;

[0065] Solution C: An aqueous solution of NaBH4 with a molar concentration of 0.1 M;

[0066] Solution D: An aqueous solution of H2PtCl6, with a Pt mass concentration of 10 mg / mL;

[0067] 0.5 mL of solution A and 1 mL of solution B were added to 100 mL of deionized water and stirred for 1 h. Then, 5 mL of solution C was added dropwise and stirred for 2 h. Then, 0.5 mL of solution D was added and stirred for another 2 h. Then, 5 mL of solution C was added dropwise and the mixture was sealed and allowed to stand for 48 h. After adding 1 g of CeO2 support, nitric acid was added dropwise to adjust the pH to 2 while stirring vigorously. The mixture was filtered and washed with deionized water until no Cl- was detected in the filtrate. The solution was dried at 50 °C for 6 h to obtain the Au@Pt / CeO2 catalyst. The average particle size of the catalyst prepared in this example was 6.78 nm.

[0068] Comparative Example 1: Au loaded onto CeO2 by liquid-phase reduction with sodium borohydride

[0069] Solution A: An aqueous solution of HAuCl4, with a Au concentration of 10 mg / mL;

[0070] Solution B: An aqueous solution of PVA, with a PVA mass fraction of 0.5%;

[0071] Solution C: An aqueous solution of NaBH4 with a molar concentration of 0.1 M;

[0072] Add 1 mL of solution A and 1 mL of solution B to 100 mL of deionized water and stir for 1 h. Then add 5 mL of solution C dropwise, seal and let stand for 48 h. Then add 1 g of CeO2 support, add nitric acid dropwise to adjust pH to 2 and stir vigorously. Filter and wash with deionized water until no Cl- is detected in the filtrate. Dry at 50 °C for 6 h to obtain Au / CeO2 catalyst.

[0073] Comparative Example 2: Pt loaded onto CeO2 by hydrogen liquid-phase reduction

[0074] Solution A: An aqueous solution of H2PtCl6, with a Pt mass concentration of 10 mg / mL;

[0075] Solution B: An aqueous solution of PVA, with a PVA mass fraction of 0.5%;

[0076] Solution C: An aqueous solution of NaBH4 with a molar concentration of 0.1 M;

[0077] Add 1 mL of solution A and 1 mL of solution B to 100 mL of deionized water, stir for 1 h, bubble with hydrogen for 2 h, and let stand in a sealed container for 48 h. Then add 1 g of CeO2 support, add nitric acid dropwise to adjust pH to 2 while stirring vigorously, filter and wash with deionized water until no Cl- is detected in the filtrate, and dry at 50 °C for 6 h to obtain the Pt / CeO2 catalyst.

[0078] The electronic and geometric structures of the Pt / CeO2 catalyst prepared in this comparative example are compared with those of the Au@Pt / CeO2 catalyst prepared in Example 1. Figure 4-5 As shown. By Figure 4 It can be seen that the Pt 4f of the core-shell structure Au@Pt / CeO2 7 / 2 The position of Au@Pt / CeO2 is significantly shifted towards lower binding energy sites compared to single-metal Pt / CeO2, indicating that electron transfer occurred from the Au core to the Pt shell, resulting in a more negative valence state for the surface Pt atoms. Figure 5 It can be seen that the CO absorption peak of the core-shell structure Au@Pt / CeO2 is almost unchanged compared with that of single metal Pt / CeO2, which indicates that the surface geometry of Au@Pt / CeO2 is almost unchanged compared with Pt / CeO2.

[0079] Test case

[0080] The catalytic effects of the catalysts prepared in Comparative Examples 1-2 and 1-2 were compared using tetrahydrofurfuryl alcohol as the reaction substrate. Reaction conditions: 0.15 g of the catalysts prepared in Examples 1-2 and 1-2 were added to a 30 mL water system with a tetrahydrofurfuryl alcohol concentration of 0.01 M. The oxygen pressure was maintained at 0.1 MPa and the temperature at 100 °C for 3 h.

[0081] The tetrahydrofurfuryl alcohol conversion and tetrahydrofurfuryl acid yield obtained in this experiment are shown in Table 1. As can be seen from Table 1, the gold catalyst alone has almost no activity for alcohol oxidation without the addition of an external base. Compared to the platinum catalyst Pt / CeO2 alone, the Au@Pt / CeO2 catalyst prepared in this invention can significantly improve the tetrahydrofurfuryl alcohol conversion and tetrahydrofurfuryl acid yield, and its catalytic performance is even better when the catalyst particle size is smaller.

[0082] Table 1. Catalytic effects of the catalysts prepared in Examples 1-2 and Comparative Examples 1-2 on the oxidation of tetrahydrofurfuryl alcohol.

[0083] catalyst Tetrahydrofurfuryl alcohol conversion rate (%) Tetrahydrofuranic acid yield (%) <![CDATA[Example 1 (Au@Pt / CeO2)]]> 99 95 <![CDATA[Example 2 (Au@Pt / CeO2)]]> 85 73 <![CDATA[Comparative Example 1 (Au / CeO2)]]> 8 5 <![CDATA[Comparative Example 2 (Pt / CeO2)]]> 35 27

[0084] Catalyst performance evaluation

[0085] Catalytic System Comparison: The catalytic system of the Au@Pt / CeO2 catalyst prepared in Example 1 was compared with that of existing alcohol oxidation catalysts in the catalytic reaction of tetrahydrofurfuryl alcohol. The results are shown in Table 2. Table 2 shows that the reaction conditions of the catalytic system involving the Au@Pt / CeO2 catalyst prepared in this example are milder than those of existing alcohol catalysts, allowing for reactions at lower temperatures or pressures, and achieving higher tetrahydrofurfuryl alcohol conversion and tetrahydrofurfuryl acid yield. Furthermore, the Au@Pt / CeO2 catalyst prepared in Example 1 can oxidize alcohols to the corresponding carboxylic acids without the addition of an external alkali, reducing the corrosion of equipment by the alkali solution and avoiding the problem of difficult separation of products in the form of free salts.

[0086] Table 2. Comparison of the catalytic systems of the Au@Pt / CeO2 catalyst prepared in Example 1 with existing catalysts.

[0087]

[0088] Improvement of Oxygen Poisoning by Au@Pt / CeO2 Catalyst: Generally, a negative reaction order indicates that the substance is excessively adsorbed at the active site to the point of saturation, or even has a poisoning effect on the reaction. The changes in reaction order between the Au@Pt / CeO2 catalyst prepared in Comparative Example 1 and the Pt / CeO2 catalyst prepared in Comparative Example 2 in the catalytic oxidation of tetrahydrofurfuryl alcohol are shown in Table 3. Table 3 shows that the oxygen order of the core-shell structured Au@Pt / CeO2 is 0, while the reaction order of Pt / CeO2 is -0.8. This indicates that the Au@Pt / CeO2 catalyst reduces the adsorption intensity of oxygen and improves the poisoning phenomenon of oxygen on platinum alone. This is mainly due to the electron transfer from the gold core inside the catalyst particles to the outer platinum layer, resulting in an electron-rich state on the platinum surface. Individual platinum particles adsorb oxygen too strongly, leading to poisoning, while the negative valence of platinum can weaken oxygen adsorption and improve the poisoning phenomenon, while simultaneously balancing the adsorption intensity of oxygen and the substrate.

[0089] Table 3. Substrate order and oxygen order of the catalysts prepared in Example 1 and Comparative Example 2

[0090] catalyst Substrate series oxygen levels <![CDATA[Pt / CeO2]]> 0 -0.8 <![CDATA[Au@Pt / CeO2]]> 0.3 0

[0091] The reaction activity of Au@Pt / CeO2 catalyst changes with reaction time: The reaction conditions are as follows: the concentration of tetrahydrofurfuryl alcohol is 0.01M in a 30mL water system, 0.15g of the catalyst prepared in Example 1 is added, the oxygen pressure is maintained at 0.1MPa, the temperature is 100℃, and the reaction time is varied.

[0092] The changes in reactant conversion and product yield of the catalyst prepared in Example 1 during the catalytic oxidation of tetrahydrofurfuryl alcohol with reaction time are shown in Table 4. Table 4 shows that as the reaction time increases, both the conversion of tetrahydrofurfuryl alcohol and the yield of tetrahydrofuronic acid continuously increase. When the reaction time reaches 3 hours, complete substrate conversion and a 92% yield of tetrahydrofuronic acid can be achieved.

[0093] Table 4. Changes in the reactivity of the Au@Pt / CeO2 catalyst prepared in Example 1 as a function of reaction time.

[0094] Time (h) Tetrahydrofurfuryl alcohol conversion rate (%) Tetrahydrofuranic acid yield (%) 0.5 78 34 1 92 57 1.5 96 71 2 98 80 2.5 100 87 3 100 92

[0095] The reaction activity of the Au@Pt / CeO2 catalyst as a function of oxygen pressure: The reaction conditions were as follows: 0.01 M tetrahydrofurfuryl alcohol in 30 mL of water, 0.15 g of the catalyst prepared in Example 1 was added, the oxygen pressure was varied, the temperature was 100 °C, and the reaction was carried out for 3 h. The reaction results are shown in Table 5.

[0096] Table 5. Reactivity of the Au@Pt / CeO2 catalyst prepared in Example 1 as a function of oxygen pressure.

[0097] <![CDATA[O2(MPa)]]> Tetrahydrofurfuryl alcohol conversion rate (%) Tetrahydrofuranic acid yield (%) 0.1 100 92 0.2 100 94 0.3 100 95 0.4 100 96 0.5 100 95

[0098] As shown in Table 5, changing the oxygen pressure within a certain range does not significantly alter the conversion rate of tetrahydrofurfuryl alcohol or the yield of tetrahydrofurfuryl acid.

[0099] The reaction activity of Au@Pt / CeO2 catalyst varies with reaction temperature: The reaction conditions are as follows: the concentration of tetrahydrofurfuryl alcohol is 0.01M in a 30mL water system, 0.15g of the catalyst prepared in Example 1 is added, the oxygen pressure is maintained at 0.1MPa, the temperature is changed, and the reaction is carried out for 3h.

[0100] 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 tetrahydrofurfuryl acid continue to increase. After the temperature rises to 100℃, the conversion rate and yield reach their highest points and remain almost unchanged.

[0101] Table 6. Reactivity of the Au@Pt / CeO2 catalyst prepared in Example 1 with reaction temperature.

[0102] Temperature (°C) Tetrahydrofurfuryl alcohol conversion rate (%) Tetrahydrofuranic acid yield (%) 60 47 7 70 69 23 80 86 47 90 95 70 100 100 92 110 100 95 120 100 96

[0103] Cyclic stability test of Au@Pt / CeO2 catalyst: The reaction conditions were as follows: 0.075 g of the catalyst prepared in Example 1 was added to a 30 mL water system with a tetrahydrofurfuryl alcohol concentration of 0.01 M, and the oxygen pressure was maintained at 0.1 MPa. The reaction was carried out at 90 °C for 3 h. After the reaction, the catalyst was filtered, washed, dried, and recycled for reuse. The same operation was repeated. The reaction results are shown in Table 7.

[0104] Table 7. Cyclic stability test results of the Au@Pt / CeO2 catalyst prepared in Example 1

[0105] Loop count Tetrahydrofurfuryl alcohol conversion rate (%) Tetrahydrofuranic acid yield (%) 1 78 29 2 77 30 3 77 28 4 76 27 5 75 25 6 73 26 7 72 25

[0106] As shown in Table 7, after multiple cycles of use, the conversion rate of tetrahydrofurfuryl alcohol and the yield of tetrahydrofurfuryl acid did not change significantly, indicating that the catalyst prepared by this method has good stability.

[0107] Substrate universality of Au@Pt / CeO2 catalyst: To verify the oxidative universality of this catalyst for various alcohol substrates, representative alcohols were selected from aliphatic, aromatic, short-chain, long-chain, linear, cyclic, monohydric, and dihydric alcohols as reaction substrates. The reaction conditions were as follows: substrate concentration of 0.01 M in 30 mL of water, addition of 0.075 g of the catalyst prepared in Example 1, maintaining an oxygen pressure of 0.1 MPa, and reacting at 90 °C for 3 h.

[0108] The reaction results are shown in Table 8. The overall catalytic activity is aromatic > aliphatic, short chain > long chain, linear > cyclic, and 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.

[0109] Table 8. Conversion rates and target product yields of different reaction substrates for the Au@Pt / CeO2 catalyst prepared in Example 1.

[0110]

Claims

1. The application of an Au@Pt core-shell structured supported catalyst in alcohol oxidation reactions, comprising a support and Au@Pt nanoparticles supported on the support, 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. The particle size distribution of the Au@Pt nanoparticles is as follows: the proportion of particles with a diameter < 3.25 nm is 0-20%, the proportion of particles with a diameter 3.25 nm ≤ 6.25 nm is 46-78%, and the proportion of particles with a diameter 6.25 nm < 10 nm is 1.5-54%. The support is at least one of TiO2, Al2O3, ZrO2, SiO2, CeO2, ZnO, MgO, Fe2O3, or carbon materials. The mass ratio of the sum of Au and Pt to the support in the Au@Pt core-shell structure supported catalyst is 0.5-10:

100.

2. The application of the Au@Pt core-shell structured supported catalyst according to claim 1 in alcohol oxidation reactions, characterized in that, The preparation method of the Au@Pt core-shell structured supported catalyst includes the following steps: (1) Disperse the gold source in a solvent to obtain a gold source solution, add a surfactant to the gold source solution, and obtain a mixed solution after dissolution; (2) Add a reducing agent to the mixed solution obtained in step (1) to react and obtain a mixed solution in which gold particles are dispersed; (3) Add a platinum source to the mixed solution obtained in step (2), and then add a reducing substance to react and obtain a mixed solution with gold core platinum shell nanoparticles dispersed in it. (4) Add the support to the mixed solution of gold core and platinum shell nanoparticles obtained in step (3), adjust the pH value of the mixed solution to be no higher than the isoelectric point of the support and stir, wash, separate and dry to obtain Au@Pt core-shell structure supported catalyst.

3. The application of the Au@Pt core-shell structured supported catalyst according to claim 2 in alcohol oxidation reactions, characterized in that, In step (1), the gold source is at least one of chloroauric acid and triphenylphosphine gold, 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.

4. The application of the Au@Pt core-shell structured supported catalyst according to claim 2 in alcohol oxidation reactions, characterized in that, In step (1), the surfactant is at least one of sodium dodecyl sulfate, sodium octyl sulfonate, sodium dodecylbenzene sulfonate, polyacrylonitrile, polyvinylpyrrolidone, polyvinyl butyral, or polyvinyl alcohol, and the molar ratio of the gold source to the surfactant is 0.1-10:

1.

5. The application of the Au@Pt core-shell supported catalyst according to claim 2 in alcohol oxidation reactions, characterized in that, In step (3), the platinum source is at least one of chloroplatinic acid, platinum trichloride or platinum nitrate, and the molar ratio of the gold source to the platinum source is 0.01-99:

1.

6. The application of the Au@Pt core-shell structured supported catalyst according to claim 2 in alcohol oxidation reactions, characterized in that, In steps (2) and (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.

7. The application of the Au@Pt core-shell structured supported catalyst according to claim 1 in alcohol oxidation reactions, characterized in that, The reaction conditions for the Au@Pt core-shell supported catalyst used in alcohol oxidation reactions are as follows: reaction temperature 30-150°C and oxygen pressure 0.1-2.0 MPa for 1-48 h.

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