A catalyst for enhancing oxidation of benzyl alcohol and a preparation method and application thereof

Abstract

The application discloses a catalyst for enhancing benzyl alcohol oxidation and a preparation method and application thereof, and belongs to the technical field of photocatalytic oxidation. Bismuth nitrate is dissolved in ethylene glycol to obtain solution A; potassium chloride is dissolved in water to obtain solution B; the solution B is poured into the solution A and stirred to obtain BiOCl; then BiOCl, Bi2O3, Ta2O5, KCl and NaCl are ground and calcined, the obtained product is added into water and stirred, the precipitate is washed and dried to obtain Bi4TaO8Cl; finally, Bi4TaO8Cl and polyvinylpyrrolidone are dissolved in water, NaBH4 and PdCl2 are added and stirred, and washing, drying are conducted to obtain Pd-Bi-Bi4TaO8Cl. The application introduces Pd and Bi bimetal on the surface of Bi4TaO8Cl, accelerates the oxidation reaction rate of benzyl alcohol, and improves the catalytic efficiency and stability. Moreover, the catalyst has very high selectivity to benzaldehyde in the benzyl alcohol oxidation process, and effectively reduces the generation of by-products.

Description

Technical Field

[0001] This invention belongs to the field of photocatalytic oxidation technology, specifically relating to a catalyst for enhancing benzyl alcohol oxidation, its preparation method, and its application. Background Technology

[0002] The selective oxidation of aromatic alcohols is a key functional group transformation process in organic synthesis and an important organic chemical reaction in modern processes and fine chemicals. Benzaldehyde, the counterpart of aromatic alcohols such as benzyl alcohol, is a commonly used chemical raw material with wide applications in dyes, pharmaceuticals, and fragrances. The classic industrial production of benzaldehyde involves chlorinating toluene to obtain benzyl chloride, followed by hydrolysis to obtain benzaldehyde. Although this process is simple and yields a large amount of benzaldehyde, it generates a large amount of corrosive products, causing severe corrosion to equipment. Photocatalytic selective oxidation of benzyl alcohol to benzaldehyde can be carried out under mild conditions using economical and clean solar energy, showing great promise.

[0003] In recent years, bismuth-based composite oxide photocatalysts have attracted great interest from researchers due to their unique electronic structure, excellent visible light absorption, and high organic matter degradation capabilities. However, the photocatalytic activity and stability of reported bismuth-based photocatalysts still need to be improved due to their structural and functional defects. Summary of the Invention

[0004] To address the shortcomings of the prior art, this invention provides a catalyst for enhancing benzyl alcohol oxidation, its preparation method, and its application.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A method for preparing a catalyst to enhance the oxidation of benzyl alcohol includes the following steps:

[0007] (1) Dissolve bismuth nitrate in ethylene glycol to obtain solution A; dissolve potassium chloride in water to obtain solution B; pour solution B into solution A and stir at room temperature; wash, dry and collect the precipitate to obtain BiOCl;

[0008] (2) Grind and mix BiOCl, Bi2O3, Ta2O5, KCl and NaCl, then calcine them in a muffle furnace. After cooling the product, add it to water, stir at room temperature, wash and dry the precipitate to obtain Bi4TaO8Cl.

[0009] (3) Dissolve Bi4TaO8Cl and polyvinylpyrrolidone in water, then add NaBH4 and PdCl2, stir, wash and dry to obtain Pd-Bi-Bi4TaO8Cl.

[0010] In a preferred embodiment of the present invention, the concentration of bismuth nitrate in solution A is 0.2–0.6 mol / L, the concentration of KCl in solution B is 0.2–0.6 mol / L, and the volume ratio of solution A to solution B is 1:1.

[0011] As a preferred embodiment of the present invention, the molar ratio of BiOCl, Bi2O3, Ta2O5, KCl and NaCl is (2-5):(3-8):(1-3):(150-180):(180-220).

[0012] In a preferred embodiment of the present invention, the calcination temperature is 600-800℃ and the time is 8-14h.

[0013] In a preferred embodiment of the present invention, the Bi4TaO8Cl and polyvinylpyrrolidone are dissolved in water, wherein the concentration of Bi4TaO8Cl is 1-4 g / L and the concentration of polyvinylpyrrolidone is 3-10 g / L.

[0014] In a preferred embodiment of the present invention, the mass ratio of Bi4TaO8Cl, NaBH4 and PdCl2 is (0.05~0.15):(0.01~0.05):(0.001~0.005).

[0015] The present invention also claims protection for the catalyst for enhancing benzyl alcohol oxidation prepared by the method for preparing the catalyst for enhancing benzyl alcohol oxidation.

[0016] The present invention also claims protection for the use of the catalyst for enhancing benzyl alcohol oxidation in photocatalytic benzyl alcohol oxidation.

[0017] Compared with existing technologies, the beneficial effects of this invention are as follows: By introducing Pd and Bi bimetals onto the Bi4TaO8Cl surface, this invention accelerates the oxidation rate of benzyl alcohol, improving catalytic efficiency and stability. Furthermore, the catalyst exhibits extremely high selectivity for benzaldehyde during the benzyl alcohol oxidation process, effectively reducing the formation of byproducts. In addition, the high efficiency and stability of the catalyst described in this invention can significantly reduce production costs, decrease energy consumption, and improve production efficiency in industrial applications, resulting in significant economic benefits. Attached Figure Description

[0018] Figure 1 The images show the XRD patterns of the catalysts prepared in Examples 1, 1, and 2.

[0019] Figure 2 The image shows the morphology of the material prepared in Example 1; a is a SEM image; b is an HRTEM image; c is an EDX elemental mapping image.

[0020] Figure 3The graph shows the benzyl alcohol conversion and benzaldehyde selectivity performance of the catalysts prepared in Example 1, Comparative Examples 1 and 2.

[0021] Figure 4 The DRS diagrams are for the catalysts prepared in Examples 1, 1, and 2.

[0022] Figure 5 The graphs show the benzyl alcohol conversion and benzaldehyde selectivity performance of the catalysts prepared in Examples 1-5.

[0023] Figure 6 This is a cyclic stability test diagram of the photocatalytic selective benzyl alcohol oxidation under the same reaction conditions in Example 1.

[0024] In the figure, BTC is the Bi4TaO8Cl catalyst prepared in Comparative Example 1, Bi-BTC is the Bi-Bi4TaO8Cl catalyst prepared in Comparative Example 2, and Pd-Bi-BTC is the Pd-Bi-Bi4TaO8Cl catalyst prepared in Example 1. Detailed Implementation

[0025] To better illustrate the purpose, technical solution, and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0026] Example 1

[0027] A method for preparing a catalyst to enhance the oxidation of benzyl alcohol includes the following steps:

[0028] (1) Dissolve 10 mmol of bismuth nitrate (Bi(NO3)3·5H2O) in 25 mL of ethylene glycol to obtain solution A; dissolve 10 mmol of potassium chloride (KCl) in 25 mL of deionized water to obtain solution B; pour solution B into solution A and stir at room temperature for 1 h, then let stand to separate the layers, discard the supernatant, wash the resulting suspension three times thoroughly with distilled water and anhydrous ethanol respectively, filter to separate and remove other ions, and then dry at 80 °C overnight to collect BiOCl.

[0029] (2) Grind and mix 0.5 mmol BiOCl, 0.75 mmol Bi2O3, 0.25 mmol Ta2O5, 40 mmol KCl and 50 mmol NaCl, then calcine in a muffle furnace at 700 °C for 14 h. After cooling the product, add 60 mL of deionized water, stir at room temperature for 1 h, let stand to separate the layers, discard the supernatant, wash the resulting suspension thoroughly three times with distilled water and anhydrous ethanol, filter and separate, then dry at 80 °C overnight to collect Bi4TaO8Cl nanosheets.

[0030] (3) Dissolve 0.10g Bi4TaO8Cl and 0.20g polyvinylpyrrolidone in 40mL of deionized water, then add 0.025g NaBH4 and 0.003g PdCl2 and stir at 350r / min for 0.5h. Wash three times with deionized water and ethanol at 60℃ respectively, filter and separate, and then dry at 80℃ overnight to obtain Pd-Bi-Bi4TaO8Cl bimetallic site photocatalyst.

[0031] Figure 2 These are scanning electron microscope (SEM), transmission electron microscope (TEM), and energy-dispersive X-ray spectroscopy (EDX) elemental mapping images of the bimetallic site photocatalyst prepared in Example 1. Figure 2 As can be seen from a, the Pd-Bi-Bi4TaO8Cl bimetallic site photocatalyst is composed of well-grown square nanoplates with a suitable amount of nanodots evenly distributed on the surface. Figure 2 b shows obvious lattice fringes, with a lattice spacing of 0.386 nm on the nanosheets, corresponding to the (110) crystal plane of Bi4TaO8Cl. The lattice spacings of the loaded particles are 0.227 nm and 0.237 nm, respectively, corresponding to the (111) crystal plane of Pd and the (104) crystal plane of Bi. Figure 2 c shows that Pd and Bi elements are uniformly distributed on the Bi4TaO8Cl support.

[0032] Example 2

[0033] A method for preparing a catalyst to enhance the oxidation of benzyl alcohol includes the following steps:

[0034] (1) Dissolve 5 mmol of bismuth nitrate (Bi(NO3)3·5H2O) in 25 mL of ethylene glycol to obtain solution A; dissolve 5 mmol of potassium chloride (KCl) in 25 mL of deionized water to obtain solution B; pour solution B into solution A and stir at room temperature for 1 h, then let stand to separate the layers, discard the supernatant, wash the resulting suspension thoroughly three times with distilled water and anhydrous ethanol respectively, filter to separate and remove other ions, and then dry at 80 °C overnight to collect BiOCl.

[0035] (2) 0.5 mmol BiOCl, 0.75 mmol Bi2O3, 0.25 mmol Ta2O5, 40 mmol KCl and 50 mmol NaCl were ground and mixed, and then calcined in a muffle furnace at 600 °C for 12 h. After the product was cooled, 100 mL of deionized water was added, and the mixture was stirred at room temperature for 3 h and then allowed to stand to separate into layers. The supernatant was discarded, and the resulting suspension was thoroughly washed three times with distilled water and anhydrous ethanol, and then filtered and separated. The suspension was then dried at 80 °C overnight to collect Bi4TaO8Cl nanosheets.

[0036] (3) Dissolve 0.05g Bi4TaO8Cl and 0.40g polyvinylpyrrolidone in 40mL of deionized water, then add 0.05g NaBH4 and 0.001g PdCl2 and stir at 450r / min for 2h. Wash three times with deionized water and ethanol at 60℃ respectively, filter and separate, and then dry at 80℃ overnight to collect 1% Pd-Bi-Bi4TaO8Cl bimetallic site photocatalyst.

[0037] Example 3

[0038] A method for preparing a catalyst to enhance the oxidation of benzyl alcohol includes the following steps:

[0039] (1) Dissolve 15 mmol of bismuth nitrate (Bi(NO3)3·5H2O) in 25 mL of ethylene glycol to obtain solution A; dissolve 15 mmol of potassium chloride (KCl) in 25 mL of deionized water to obtain solution B; pour solution B into solution A and stir at room temperature for 1 h, then let stand to separate the layers, discard the supernatant, wash the resulting suspension thoroughly three times with distilled water and anhydrous ethanol respectively, filter to separate and remove other ions, and then dry at 80 °C overnight to collect BiOCl.

[0040] (2) Grind and mix 0.5 mmol BiOCl, 0.75 mmol Bi2O3, 0.25 mmol Ta2O5, 40 mmol KCl and 50 mmol NaCl, then calcine in a muffle furnace at 800 °C for 10 h. After cooling the product, add 100 mL of deionized water, stir at room temperature for 3 h, let stand to separate the layers, discard the supernatant, wash the resulting suspension thoroughly three times with distilled water and anhydrous ethanol, filter and separate, then dry at 80 °C overnight to collect Bi4TaO8Cl nanosheets.

[0041] (3) Dissolve 0.15g Bi4TaO8Cl and 0.12g polyvinylpyrrolidone in 40mL of deionized water, then add 0.01g NaBH4 and 0.002g PdCl2 and stir at 250r / min for 1h. Wash three times with deionized water and ethanol at 60℃ respectively, filter and separate, and then dry at 80℃ overnight to collect 2% Pd-Bi-Bi4TaO8Cl bimetallic site photocatalyst.

[0042] Example 4

[0043] (1) Dissolve 10 mmol of bismuth nitrate (Bi(NO3)3·5H2O) in 25 mL of ethylene glycol to obtain solution A; dissolve 10 mmol of potassium chloride (KCl) in 25 mL of deionized water to obtain solution B; pour solution B into solution A and stir at room temperature for 1 h, then let stand to separate the layers, discard the supernatant, wash the resulting suspension three times thoroughly with distilled water and anhydrous ethanol respectively, filter to separate and remove other ions, and then dry at 80 °C overnight to collect BiOCl.

[0044] (2) Grind and mix 0.5 mmol BiOCl, 0.75 mmol Bi2O3, 0.25 mmol Ta2O5, 40 mmol KCl and 50 mmol NaCl, then calcine in a muffle furnace at 700 °C for 9 h. After cooling the product, add 60 mL of deionized water, stir at room temperature for 1 h, and let stand to separate the layers. Discard the supernatant, wash the resulting suspension thoroughly three times with distilled water and anhydrous ethanol, filter and separate, and then dry at 80 °C overnight to collect Bi4TaO8Cl nanosheets.

[0045] (3) Dissolve 0.10g Bi4TaO8Cl and 0.20g polyvinylpyrrolidone in 40mL of deionized water, then add 0.025g NaBH4 and 0.004g PdCl2 and stir at 350r / min for 0.5h. Wash three times with deionized water and ethanol at 60℃ respectively, filter and separate, and then dry at 80℃ overnight to collect 4% Pd-Bi-Bi4TaO8Cl bimetallic site photocatalyst.

[0046] Example 5

[0047] (1) Dissolve 10 mmol of bismuth nitrate (Bi(NO3)3·5H2O) in 25 mL of ethylene glycol to obtain solution A; dissolve 10 mmol of potassium chloride (KCl) in 25 mL of deionized water to obtain solution B; pour solution B into solution A and stir at room temperature for 1 h, then let stand to separate the layers, discard the supernatant, wash the resulting suspension three times thoroughly with distilled water and anhydrous ethanol respectively, filter to separate and remove other ions, and then dry at 80 °C overnight to collect BiOCl.

[0048] (2) 0.5 mmol BiOCl, 0.75 mmol Bi2O3, 0.25 mmol Ta2O5, 40 mmol KCl and 50 mmol NaCl were ground and mixed, and then calcined in a muffle furnace at 700 °C for 8 h. After the product was cooled, 60 mL of deionized water was added, and the mixture was stirred at room temperature for 1 h and allowed to stand to separate into layers. The supernatant was discarded, and the resulting suspension was thoroughly washed three times with distilled water and anhydrous ethanol, and then filtered and separated. The suspension was then dried at 80 °C overnight to collect Bi4TaO8Cl nanosheets.

[0049] (3) Dissolve 0.10g Bi4TaO8Cl and 0.20g polyvinylpyrrolidone in 40mL of deionized water, then add 0.025g NaBH4 and 0.005g PdCl2 and stir at 350r / min for 0.5h. Wash three times with deionized water and ethanol at 60℃ respectively, filter and separate, and then dry at 80℃ overnight to collect 5% Pd-Bi-Bi4TaO8Cl bimetallic site photocatalyst.

[0050] Comparative Example 1

[0051] A method for preparing a Bi4TaO8Cl catalyst includes the following steps:

[0052] (1) Dissolve 10 mmol of bismuth nitrate (Bi(NO3)3·5H2O) in 25 mL of ethylene glycol to obtain solution A; dissolve 10 mmol of potassium chloride (KCl) in 25 mL of deionized water to obtain solution B; pour solution B into solution A and stir at room temperature for 1 h, then let stand to separate the layers, discard the supernatant, wash the resulting suspension three times thoroughly with distilled water and anhydrous ethanol respectively, filter to separate and remove other ions, and then dry at 80 °C overnight to collect BiOCl.

[0053] (2) Grind and mix 0.5 mmol BiOCl, 0.75 mmol Bi2O3, 0.25 mmol Ta2O5, 40 mmol KCl and 50 mmol NaCl, then calcine them in a muffle furnace at 700 °C for 14 h. After cooling the product, add 60-100 mL of deionized water, stir at room temperature for 1 h, let stand to separate the layers, discard the supernatant, wash the resulting suspension thoroughly three times with distilled water and anhydrous ethanol, filter and separate, then dry at 80 °C overnight to collect the Bi4TaO8Cl photocatalyst.

[0054] Comparative Example 2

[0055] A method for preparing a Bi-Bi4TaO8Cl catalyst includes the following steps:

[0056] (1) Dissolve 10 mmol of bismuth nitrate (Bi(NO3)3·5H2O) in 25 mL of ethylene glycol to obtain solution A; dissolve 10 mmol of potassium chloride (KCl) in 25 mL of deionized water to obtain solution B; pour solution B into solution A and stir at room temperature for 1 h, then let stand to separate the layers, discard the supernatant, wash the resulting suspension three times thoroughly with distilled water and anhydrous ethanol respectively, filter to separate and remove other ions, and then dry at 80 °C overnight to collect BiOCl.

[0057] (2) Grind and mix 0.5 mmol BiOCl, 0.75 mmol Bi2O3, 0.25 mmol Ta2O5, 40 mmol KCl and 50 mmol NaCl, and then calcine them in a muffle furnace at 700 °C for 14 h. After cooling the product, add 60-100 mL of deionized water, stir at room temperature for 1 h, and let stand to separate the layers. Discard the supernatant, wash the resulting suspension thoroughly three times with distilled water and anhydrous ethanol, filter and separate, and then dry at 80 °C overnight to collect Bi4TaO8Cl nanosheets.

[0058] (3) Dissolve 0.10g Bi4TaO8Cl and 0.20g polyvinylpyrrolidone in 40mL of deionized water, then add 0.025g NaBH4 and stir at 350r / min for 0.5h. Wash three times with deionized water and ethanol at 60-80℃ respectively, filter and separate, and then dry at 80℃ overnight to collect Bi-Bi4TaO8Cl single metal site photocatalyst.

[0059] Figure 1 The figures show the X-ray diffraction patterns of the photocatalysts prepared in Example 1, Comparative Example 1, and Comparative Example 2. The figures demonstrate the successful preparation of Bi₄TaO₈Cl, Bi-Bi₄TaO₈Cl, and Pd-Bi-Bi₄TaO₈Cl. The peak intensities change with material modification, indicating a transformation in material properties. However, due to the low crystallinity of Pd, no obvious diffraction peaks were observed.

[0060] Figure 4 The images show the UV-vis DRS diagrams of the photocatalysts prepared in Example 1, Comparative Example 1, and Comparative Example 2. It can be seen from the figures that the absorption edge of Pd-Bi-Bi4TaO8Cl prepared in Example 1 shows a significant red shift compared to Comparative Example 1 and Comparative Example 2, indicating that the Pd-Bi bimetallic sites significantly enhance the light-harvesting ability of the material.

[0061] Example of effect

[0062] The catalysts prepared in the examples and comparative examples were used for the photocatalytic oxidation of benzyl alcohol. The specific steps are as follows:

[0063] (1) Take 20 mg of catalyst and place it in a 50 mL photoreaction tube. Use cooling water to control the reaction temperature at room temperature.

[0064] (2) Transfer 21 μL of benzyl alcohol (BA) and 2 mL of benzene trifluoride (BTF) into a test tube. Sonicate the mixture in an ultrasonic cleaner for about 5 min to ensure uniform mixing. Finally, stir the mixture in the dark for 30 min to allow the catalyst and BA to reach an adsorption-desorption equilibrium.

[0065] (3) Before the reaction begins, O2 is blown into the solution for 20 minutes to saturate the O2 concentration. A 300W xenon lamp equipped with a 400nm cutoff filter is used to simulate the solar light source. After continuous irradiation for 4 hours, the suspension is collected and filtered through a 0.45μm filter membrane to remove the catalyst.

[0066] (4) The filtrate was analyzed by high performance liquid chromatography (HPLC), and the conversion rate of BA and the selectivity of benzaldehyde (BD) were calculated. The results are shown in Table 1.

[0067] Table 1

[0068] Selectivity of benzaldehyde / % Benzyl alcohol conversion rate / % Example 1 98.78 86.88 Example 2 97.36 56.88 Example 3 97.72 76.88 Example 4 98.01 81.88 Example 5 98.84 69.88 Comparative Example 1 97.70 24.12 Comparative Example 2 98.10 39.37

[0069] according to Figure 3 , Figure 5 As shown in Table 1, the bimetallic site photocatalyst prepared in Example 1 exhibits significantly enhanced selective oxidation ability. After four hours of illumination, its conversion rate reaches a maximum of 86.88%, with a selectivity of 98.78%. Examples 2-5 show that the selectivity of Pd-Bi-BTC photocatalysts with different Pd contents decreases. Furthermore, the selective oxidation ability of the Bi4TaO8Cl catalyst prepared in Comparative Example 1 and the Bi-Bi4TaO8Cl monometallic site photocatalyst prepared in Comparative Example 2 is significantly reduced, indicating that the introduction of bimetallic sites has a substantial promoting effect on performance improvement.

[0070] The stability test of the bimetallic site photocatalyst for the selective oxidation of benzyl alcohol prepared in Example 1 is as follows: Figure 6 As shown, multiple cyclic experiments were conducted under the same conditions, demonstrating that the Pd-Bi-BTC photocatalyst exhibits good stability. After four cycles of photocatalytic selective oxidation of benzyl alcohol, the Pd-Bi-BTC photocatalyst still maintained considerable performance. Its good stability gives it potential for large-scale application, mainly because the addition of Pb enhances the structural stability and catalytic performance stability of the Bi-BTC photocatalyst.

[0071] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. The application of a catalyst that enhances benzyl alcohol oxidation in photocatalytic benzyl alcohol oxidation, characterized in that, The preparation method of the catalyst includes the following steps: (1) Dissolve bismuth nitrate in ethylene glycol to obtain solution A; dissolve potassium chloride in water to obtain solution B; pour solution B into solution A and stir at room temperature; wash, dry and collect the precipitate to obtain BiOCl; (2) Grind and mix BiOCl, Bi2O3, Ta2O5, KCl and NaCl, then calcine them. After cooling the product, add it to water, stir at room temperature, wash and dry the precipitate to obtain Bi4TaO8Cl. (3) Dissolve Bi4TaO8Cl and polyvinylpyrrolidone in water, then add NaBH4 and PdCl2 and stir, wash and dry to obtain Pd-Bi-Bi4TaO8Cl; the mass ratio of Bi4TaO8Cl, NaBH4 and PdCl2 is (0.05~0.15):(0.01~0.05):(0.001~0.005).

2. The application as described in claim 1, characterized in that, The concentration of bismuth nitrate in solution A is 0.2~0.6 mol / L, and the concentration of KCl in solution B is 0.2~0.6 mol / L; the volume ratio of solution A to solution B is 1:

1.

3. The application as described in claim 1, characterized in that, The molar ratio of BiOCl, Bi2O3, Ta2O5, KCl and NaCl is (2~5):(3~8):(1~3):(150~180):(180~220).

4. The application as described in claim 1, characterized in that, The calcination temperature is 600-800℃, and the time is 8-14h.

5. The application as described in claim 1, characterized in that, The Bi4TaO8Cl and polyvinylpyrrolidone are dissolved in water, with the concentration of Bi4TaO8Cl being 1-4 g / L and the concentration of polyvinylpyrrolidone being 3-10 g / L.

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