A catalyst for synthesizing hydrogen peroxide, a preparation method thereof, and an application thereof

Abstract

The present invention discloses a catalyst for synthesizing hydrogen peroxide, a preparation method thereof, and an application thereof. The catalyst is a silica-modified Au / ZnO supported catalyst, and the catalyst comprises metal Au nanoparticles, ZnO, and SiO2; based on the mass of the catalyst, the content of Au nanoparticles is 0.1% to 3.0%, the content of SiO2 is 0.1% to 2.0%, and the content of ZnO is 95% to 99.8%. The catalyst of the present invention is suitable for synthesizing hydrogen peroxide from CO, O2, and H2O as raw materials, and can improve the generation rate and yield of H2O2, and has higher safety compared with the synthesis route using H2 and O2 as raw materials. Using the catalyst of the present invention can simplify the operation process of the hydrogen peroxide method and realize one-step direct synthesis.

Description

Technical Field

[0001] The present invention belongs to the field of hydrogen peroxide synthesis, and particularly relates to a catalyst for synthesizing hydrogen peroxide, a preparation method thereof, and an application thereof. Background Art

[0002] Hydrogen peroxide (H 2 O 2 ) is widely used in industrial, military, and medical fields and is an important chemical product. The annual consumption of hydrogen peroxide (H 2 O 2 ) globally can reach approximately 5 million tons per year, and the demand continues to grow at a rate of about 4% per year. Among them, the anthraquinone method contributes nearly 95% of the production capacity.

[0003] The anthraquinone method is technically mature and includes multiple processes such as hydrogenation of the anthraquinone working solution, oxidation of the hydrogenated working solution, and extraction of H 2 O 2 . The process flow is relatively complex, and the operating cost is high. Recently, there have been many studies on the direct synthesis of H 2 and O 2 into H 2 O 2 under the action of a Pd-based catalyst. The explosion limit of H 2 is wide, and considering the safety of operation, it may affect the concentration of the final product. In addition, this reaction often requires adding acids, halide ions, and organic reagents, etc. to the reaction solvent, which increases the difficulty of product separation. Therefore, there is an urgent need for a more efficient route for directly synthesizing hydrogen peroxide.

[0004] Regarding the direct synthesis of H 2 and H 2 O into H 2 O 2 using CO, O 2 O 2 as raw materials, there are very few studies on the preparation of H 2 and O 2 into hydrogen peroxide using Pd-based catalysts. Pd-based catalysts suitable for synthesizing hydrogen peroxide from H 2 and H 2 O as raw materials are not suitable for directly synthesizing H 2 O 2 using CO, O 2 O 2 as raw materials. Ma et al. (Appl.Catal.A, 2006, 311, 34) developed a P- or B-modified Ni catalyst, and its H cat -1 h -1 production rate can reach 0.228 mol kg2 O 3 The catalyst was prepared and applied to this reaction. By adjusting process conditions such as the reaction solvent, the H 2 O 2 generation rate can reach 0.326 mol kg cat -1 h -1 . The Cao research group (ACS Catalysis, 2020, 10, 13993) prepared an Au / TiO 2 catalyst. Under the condition of using acetone and water as solvents, the H 2 O 2 generation rate was increased to 74.6 mol kg cat -1 h -1 .

[0005] In summary, using CO, O 2 and H 2 O as raw materials to synthesize H 2 O 2 is safer than the synthesis route using H 2 and O 2 as raw materials. However, there is still a huge room for improvement in the product yield of this reaction. Therefore, it is very necessary to develop a new catalyst system with high activity. SUMMARY OF THE INVENTION

[0006] The object of the present invention is to provide a catalyst for synthesizing hydrogen peroxide, its preparation method and application. This catalyst can directly prepare H 2 O using CO, O 2 and H 2 O 2 as raw materials, and can significantly improve the generation rate and yield of H 2 O 2 .

[0007] The first aspect of the present invention provides a catalyst for synthesizing hydrogen peroxide. This catalyst is a silica-modified Au / ZnO supported catalyst, and the catalyst includes metallic Au nanoparticles, ZnO and SiO 2 ; based on the mass of the catalyst, the content of Au nanoparticles is 0.1% - 3.0%, the content of SiO 2 is 0.1% - 2.0%, and the ZnO content is 95% - 99.8%.

[0008] Further, based on the mass of the catalyst, the content of Au nanoparticles is 0.5% - 2.5%, and the content of SiO 2 is 0.2% - 2.0%.

[0009] Further, in the catalyst, the Au nanoparticles are wholly or partly wrapped by the SiO 2 layer. Among them, the silica is derived from tetraethyl orthosilicate.

[0010] The second aspect of the present invention provides a preparation method of a catalyst for synthesizing hydrogen peroxide, comprising the following steps:

[0011] 1) Mix a metal Au precursor solution with water to obtain Solution I;

[0012] 2) Add ZnO powder to Solution I and stir to obtain Mixture II;

[0013] 3) Add tetraethyl orthosilicate to Mixture II, stir, and then add a precipitating agent to adjust the pH to obtain a precipitate;

[0014] 4) Age the precipitate obtained in step 3), then filter and wash to obtain a filter cake;

[0015] 5) Dry and calcine the filter cake obtained in step 4) to obtain a catalyst for synthesizing hydrogen peroxide.

[0016] Further, in step 1), the metal Au precursor solution is selected from at least one of chloroauric acid tetrahydrate solution and chloroauric acid trihydrate solution. The concentration of the metal Au precursor solution is 2 - 15 mg Au / mL. In step 1), the volume ratio of the metal Au precursor solution to water is 1:30 - 1:80.

[0017] Further, in step 2), the specific surface area of the ZnO powder is 15 - 60 m 2 / g.

[0018] Further, in step 2), after adding the ZnO powder, the stirring time is preferably 10 - 30 min.

[0019] Further, in step 3), after adding tetraethyl orthosilicate, the stirring time is preferably 5 - 30 min. The precipitating agent is selected from at least one of ammonia water, ammonium carbonate or sodium hydroxide. The pH is adjusted to 7.0 - 9.0.

[0020] Further, in step 4), the aging conditions are: aging at 30 - 80 °C for 1 - 5 h. The aging is preferably carried out in a water bath. In step 4), the filtering and washing can be carried out in a conventional manner in the art.

[0021] Further, in step 5), the drying conditions are: drying at 60 - 100 °C for 6 - 16 h. The calcining conditions are: calcining at 150 - 600 °C for 1 - 4 h. The calcining is preferably carried out in a muffle furnace.

[0022] The third aspect of the present invention further provides an application of the catalyst described in the first aspect or the catalyst prepared according to the method described in the second aspect in the reaction for preparing H 2 using CO, O 2 and H 2 O as raw materials. 2

[0023] Furthermore, in the above application, H 2 O is used as the reaction solvent, CO and O 2 are used as the reaction gases, and at least one of He, N 2 and Ar is used as the reaction protective gas, and the protective gas accounts for 5% - 80% of the total gas volume.

[0024] Furthermore, in the above application, an additive is preferably added to the reaction solvent, and the additive is one or more of acetone, methanol and cyclohexane.

[0025] Furthermore, the volume ratio of O 2 / CO is 0.05 - 3, the total gas pressure of the reaction system is 0.1 - 6 MPa, preferably 3 - 5 MPa, the reaction temperature is 0 - 70 °C, preferably 50 - 70 °C, the rotation speed is 400 - 1200 rpm, and the reaction time is 5 - 120 min.

[0026] Compared with the prior art, the advantages of the present invention are as follows:

[0027] The catalyst of the present invention is applicable to the synthesis of hydrogen peroxide using CO, O 2 and H 2 O as raw materials, and can improve the generation rate and yield of H 2 O 2 , and has higher safety than the synthesis route using H 2 and O 2 as raw materials.

[0028] In the preparation method of the present invention, by modifying the Au / ZnO catalyst with tetraethyl orthosilicate (TEOS) and the specific addition sequence of TEOS, the obtained catalyst can greatly inhibit the decomposition of hydrogen peroxide and significantly improve the generation rate of the product hydrogen peroxide; moreover, the synthesis scheme simplifies the operation process, realizes one-step direct synthesis, and has good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is the HAADF-STEM image of the catalyst obtained in Example 1;

[0030] Figure 2 is the H 2 O of the catalysts obtained in Comparative Example 4, Example 1, and Comparative Example 2​2 Synthesis performance. From left to right are: the catalyst obtained in Comparative Example 4, the catalyst obtained in Example 1, and the catalyst obtained in Comparative Example 2. Detailed implementation mode

[0031] To better understand the present invention, the present invention will be further described in detail below in conjunction with embodiments, but the scope of protection required by the present invention is not limited to the embodiments.

[0032] The endpoints and any values within the ranges disclosed herein are not limited to the exact ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values within each range, between the endpoint values of each range and individual point values, and between individual point values can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0033] Example 1

[0034] Measure 2.00 mL of HAuCl Au ·4H 4 O solution with a concentration of 5.00 mg 2 / mL and add it to a 500 mL beaker that has been pre-filled with 100 mL of deionized water; then add 0.99 g of ZnO powder with a specific surface area of 35 m 2 / g, stir vigorously for 15 min, then add 4.4 g of TEOS, and stir vigorously for 5 min; subsequently add a 0.5 mol / L ammonia precipitation agent and adjust to pH = 9.0 to obtain a precipitate; age in a water bath at 80 °C for 1 h; then perform filtration and washing operations with 1.5 L of deionized water, and dry in an oven at 60 °C for 12 h; subsequently, treat the dried product in a muffle furnace at 200 °C for 1.5 h to obtain the SiO 2 -modified Au / ZnO supported catalyst. The mass percentage content of Au nanoparticles in this catalyst is 1.0 wt%, and the mass percentage content of SiO 2 is 0.9 wt%. Among them, the HAADF-STEM image of the obtained catalyst is shown in Figure 1 . It can be seen from Figure 1 that the surface of the nano-Au particles is wrapped by a layer of SiO 2 .

[0035] Weigh 5 mg of the above catalyst and 10 g of solvent H 2 O and add them to a 50 mL high-pressure reactor. Adjust the magnetic stirrer speed to 1200 rpm, raise the reaction temperature to 60 °C, and introduce 3.0 MPa of O 2, 0.2 MPa CO and 0.8 MPa He, stop the reaction after 5 min, conduct product detection, and the hydrogen peroxide generation rate is 176 mol H2O2 kg -1 h -1 。

[0036] Example 2

[0037] Measure 4.00 mL of HAuCl Au ·4H 4 O solution with a concentration of 5.00 mg 2 / mL and add it to a 500 mL beaker pre-filled with 100 mL of deionized water; then add 0.98 g of ZnO powder with a specific surface area of 35 m 2 / g, stir vigorously for 15 min, add 4.4 g of TEOS, and stir vigorously for 5 min; then add a 0.5 mol / L ammonia precipitation agent to adjust the pH to 9.0 to obtain a precipitate; age in a water bath at 80 °C for 1 h; then perform filtration and washing operations with 1.5 L of deionized water and dry in an oven at 60 °C for 12 h; subsequently, treat the dried product in a muffle furnace at 200 °C for 1.5 h to obtain the SiO 2 -modified Au / ZnO supported catalyst. The mass percentage content of Au nanoparticles in this catalyst is 2.0 wt%, and the mass percentage content of SiO 2 is 0.9 wt%. Among them, the HAADF-STEM image of the obtained catalyst is similar to that shown in Figure 1 。

[0038] Weigh 5 mg of the above catalyst and 10 g of solvent H 2 O and add them to a 50 mL high-pressure reactor. Adjust the magnetic stirrer speed to 1200 rpm, raise the reaction temperature to 60 °C, and introduce 3.0 MPa O 2 , 0.2 MPa CO and 0.8 MPa He. Stop the reaction after 5 min, conduct product detection, and the hydrogen peroxide generation rate is 143 mol H2O2 kg -1 h -1 。

[0039] Example 3

[0040] Measure 2.00 mL of HAuCl Au ·4H 4 O solution with a concentration of 5.00 mg 2 / mL and add it to a 500 mL beaker pre-filled with 100 mL of deionized water; then add ZnO powder with a specific surface area of 28 m 20.99 g of ZnO powder per gram, stir vigorously for 15 min, then add 13.2 g of TEOS and stir vigorously for 5 min; subsequently add 0.5 mol / L ammonia precipitation agent, adjust to pH = 9.0 to obtain a precipitate; age in an 80 °C water bath for 1 h; then perform filtration and washing operations with 1.5 L of deionized water and dry in a 60 °C oven for 12 h; subsequently treat the dried product in a muffle furnace at 600 °C for 1.5 h to obtain the SiO 2 modified Au / ZnO supported catalyst, in which the mass percentage content of Au nanoparticles in the catalyst is 1.0 wt%, and the mass percentage content of SiO 2 is 1.8 wt%. Among them, the HAADF-STEM image of the obtained catalyst is similar to that shown in Figure 1 .

[0041] Weigh 5 mg of the said catalyst and 10 g of solvent H 2 O and add them into a 50 mL high-pressure reactor, adjust the magnetic stirrer speed to 1200 rpm, raise the reaction temperature to 60 °C, introduce 3.0 MPa O 2 , 0.2 MPa CO and 0.8 MPa He, stop the reaction after 5 min of reaction, conduct product detection, and the hydrogen peroxide generation rate is 81 mol H2O2 kg -1 h -1 .

[0042] Example 4

[0043] Measure 2.00 mL of a HAuCl Au ·4H 4 O solution with a concentration of 5.00 mg 2 / mL and add it to a 500 mL beaker already pre-filled with 100 mL of deionized water; then add 0.99 g of ZnO powder with a specific surface area of 35 m 2 / g, stir vigorously for 15 min, then add 13.2 g of TEOS and stir vigorously for 5 min; subsequently add 0.5 mol / L ammonia precipitation agent, adjust to pH = 9.0 to obtain a precipitate; age in an 80 °C water bath for 1 h; then perform filtration and washing operations with 1.5 L of deionized water and dry in a 60 °C oven for 12 h; subsequently treat the dried product in a muffle furnace at 200 °C for 1.5 h to obtain the SiO 2 modified Au / ZnO supported catalyst, in which the mass percentage content of Au nanoparticles in the catalyst is 1.0 wt%, and the mass percentage content of SiO 2 is 1.8 wt%. Among them, the HAADF-STEM image of the obtained catalyst is similar to that shown in Figure 1 .

[0044] Weigh 5 mg of the catalyst and solvent H 2 10 g of O was added into a 50 mL high pressure reactor, the magnetic speed was adjusted to 1200 rpm, the reaction temperature was raised to 60 °C, and 3.0 MPa of O was introduced. 2 , 0.2MPa CO and He MPa O 2 After 5 minutes of reaction, the reaction was stopped and the product was detected. The hydrogen peroxide generation rate was 112 mol H2O2 kg -1 h -1 .

[0045] Example 5

[0046] The concentration is 5.00mg Au / mL HAuCl 4 ·3H 2 O solution 2.00mL, add to a 500mL beaker pre-filled with 100mL deionized water; then add 2 / g ZnO powder 0.99g, after vigorous stirring for 15min, add 8.8g TEOS, and stir vigorously for 5min; then add 0.5mol / L ammonia water precipitant, adjust to pH=8.0, and obtain a precipitate; age in 80℃ water bath for 1h; then filter and wash with 1.5L deionized water, and dry in 60℃ oven for 12h; then treat the dried product in 300℃ muffle furnace for 1.5h to obtain the SiO 2 The modified Au / ZnO supported catalyst has a mass percentage of Au nanoparticles of 1.0 wt%, SiO 2 The mass percentage of the catalyst is 1.1 wt%. The HAADF-STEM image of the obtained catalyst is similar to that shown in Figure 1 .

[0047] Weigh 10 mg of the catalyst and solvent H 2 8 g of O and 2 g of methanol were added into a 50 mL high pressure reactor. The magnetic speed was adjusted to 1200 rpm. The reaction temperature was raised to 60 °C. 3.0 MPa of O was introduced. 2 , 0.2MPa CO and 0.8MPa He, the reaction was stopped after 5 minutes, and the product was detected. The hydrogen peroxide generation rate was 85mol H2O2 kg -1 h -1 .

[0048] Example 6

[0049] The concentration is 5.00mg Au / mL HAuCl 4 ·4H2 O solution 2.00mL, add to a 500mL beaker pre-filled with 100mL deionized water; then add 2 / g ZnO powder 0.99g, after vigorous stirring for 15min, add 4.4g TEOS, and stir vigorously for 5min; then add 0.5mol / L ammonia water precipitant, adjust to pH = 9.0, and obtain a precipitate; age in 80℃ water bath for 1h; then filter and wash with 1.5L deionized water, dry in 60℃ oven for 12h; then heat the dried product at 400℃, 5vol%H 2 / N 2 The SiO 2 The modified Au / ZnO supported catalyst has a mass percentage of Au nanoparticles of 1.0 wt%, SiO 2 The mass percentage of the catalyst is 1.0 wt%. The HAADF-STEM image of the obtained catalyst is similar to that shown in Figure 1 .

[0050] Weigh 5 mg of the catalyst and solvent H 2 10 g of O was added into a 50 mL high pressure reactor, the magnetic speed was adjusted to 1200 rpm, the reaction temperature was raised to 60 °C, and 3.0 MPa of O was introduced. 2 , 0.2MPa CO and 0.8MPa He, the reaction was stopped after 5 minutes, and the product was detected. The hydrogen peroxide generation rate was 133mol H2O2 kg -1 h -1 .

[0051] Example 7

[0052] The concentration is 5.00mg Au / mL HAuCl 4 ·4H 2 O solution 2.00mL, add to a 500mL beaker pre-filled with 100mL deionized water; then add 2 0.99 g of ZnO powder was stirred vigorously for 15 min, and then 4.4 g of TEOS was added, and the mixture was stirred vigorously for 5 min; then 0.5 mol / L of ammonia water precipitant was added, and the pH was adjusted to 9.0 to obtain a precipitate; the precipitate was aged in a water bath at 80°C for 1 h; then 1.5 L of deionized water was used for filtering and washing, and the precipitate was dried in an oven at 60°C for 12 h; then the dried product was treated in a muffle furnace at 200°C for 1.5 h to obtain the SiO 2Modified Au / ZnO supported catalyst, in which the mass percentage of Au nanoparticles is 1.0 wt%, and the mass percentage of SiO 2 is 0.9 wt%. Among them, the HAADF-STEM image of the obtained catalyst is similar to that shown in Figure 1 .

[0053] Weigh 5 mg of the said catalyst and 10 g of solvent H 2 O and add them into a 50 mL high-pressure reactor. Adjust the magnetic stirrer speed to 1200 rpm, raise the reaction temperature to 65 °C, introduce 3.0 MPa O 2 , 0.2 MPa CO and 0.8 MPa He. After reacting for 5 min, stop the reaction and conduct product detection. The hydrogen peroxide generation rate is 123 mol H2O2 kg -1 h -1 .

[0054] Example 8

[0055] Measure 2.00 mL of a HAuCl Au solution with a concentration of 5.00 mg 4 / mL and add it into a 500 mL beaker that has been pre-filled with 100 mL of deionized water; then add 0.99 g of ZnO powder with a specific surface area of 35 m 2 / g, stir vigorously for 15 min, then add 4.4 g of TEOS and stir vigorously for 5 min; subsequently add a 0.5 mol / L ammonia precipitation agent to adjust the pH to 9.0 to obtain a precipitate; age in a water bath at 80 °C for 1 h; then perform filtration and washing operations with 1.5 L of deionized water and dry in an oven at 60 °C for 12 h; subsequently treat the dried product in a muffle furnace at 200 °C for 1.5 h to obtain the said SiO 2 modified Au / ZnO supported catalyst, in which the mass percentage of Au nanoparticles is 1.0 wt%, and the mass percentage of SiO 2 is 0.9 wt%. Among them, the HAADF-STEM image of the obtained catalyst is similar to that shown in 2 Figure 1 .

[0056] Weigh 5 mg of the said catalyst and 10 g of solvent H 2 O and add them into a 50 mL high-pressure reactor. Adjust the magnetic stirrer speed to 1200 rpm, raise the reaction temperature to 60 °C, introduce 2.0 MPa O 2 , 0.2 MPa CO and 1.8 MPa He. After reacting for 5 min, stop the reaction and conduct product detection. The hydrogen peroxide generation rate is 95 mol H2O2 kg -1 h​-1 .

[0057] Comparative Example 1

[0058] Measure 2.00 mL of HAuCl Au ·4H 4 O solution with a concentration of 5.00 mg 2 / mL, and add it to a 500 mL beaker that has been pre-filled with 100 mL of deionized water; then add 0.99 g of ZnO powder with a specific surface area of 35 m 2 / g, stir vigorously for 15 min, then add 1.0 g of silica sol, and stir vigorously for 5 min; subsequently add a 0.5 mol / L ammonia precipitant, adjust to pH = 9.0 to obtain a precipitate; age in a water bath at 80 °C for 1 h; then perform filtration and washing operations with 1.5 L of deionized water, and dry in an oven at 60 °C for 12 h; subsequently treat the dried product in a muffle furnace at 200 °C for 1.5 h to obtain the SiO 2 -modified Au / ZnO supported catalyst. The mass percentage content of Au nanoparticles in this catalyst is 1.0 wt%, and the mass percentage content of SiO 2 is 0.9 wt%.

[0059] Weigh 5 mg of the catalyst and 10 g of solvent H 2 O and add them to a 50 mL high-pressure reactor. Adjust the magnetic stirrer speed to 1200 rpm, raise the reaction temperature to 60 °C, introduce 3.0 MPa O 2 , 0.2 MPa CO, and 0.8 MPa He. Stop the reaction after 5 min, perform product detection, and the hydrogen peroxide generation rate is 17 mol H2O2 kg -1 h -1 .

[0060] Comparative Example 2

[0061] Measure 2.00 mL of HAuCl Au ·4H 4 O solution with a concentration of 5.00 mg 2 / mL, and add it to a 500 mL beaker that has been pre-filled with 100 mL of deionized water; then add 4.4 g of TEOS, stir vigorously for 5 min, then add 0.99 g of ZnO powder with a specific surface area of 35 m 2 / g, and stir vigorously for 15 min; subsequently add a 0.5 mol / L ammonia precipitant, adjust to pH = 9.0 to obtain a precipitate; age in a water bath at 80 °C for 1 h; perform filtration and washing operations on the precipitated product with 1.5 L of deionized water, and dry in an oven at 60 °C for 12 h; subsequently treat the dried product in a muffle furnace at 200 °C for 1.5 h to obtain the SiO2 Modified Au / ZnO supported catalyst, in which the mass percentage of Au nanoparticles is 1.0 wt%, and the mass percentage of SiO 2 is 0.9 wt%.

[0062] Weigh 5 mg of the said catalyst and 10 g of solvent H 2 O and add them into a 50 mL high-pressure reactor. Adjust the magnetic stirrer speed to 1200 rpm, raise the reaction temperature to 60 °C, and introduce 3.0 MPa O 2 , 0.2 MPa CO and 0.8 MPa He. Stop the reaction after 5 min of reaction, conduct product detection, and the hydrogen peroxide generation rate is 13 mol H2O2 kg -1 h -1 .

[0063] Comparative Example 3

[0064] Measure 2.00 mL of HAuCl Au solution with a concentration of 5.00 mg 4 / mL and add it into a 500 mL beaker pre-filled with 100 mL of deionized water; then add 0.99 g of ZnO powder with a specific surface area of 35 m 2 / g, stir vigorously for 15 min, and then add 40.5 g of TEOS and stir vigorously for 5 min; subsequently, add a 0.5 mol / L ammonia precipitation agent and adjust the pH to 9.0 to obtain a precipitate; age in a water bath at 80 °C for 1 h; then perform filtration and washing operations with 1.5 L of deionized water and dry in an oven at 60 °C for 12 h; subsequently, treat the dried product in a muffle furnace at 200 °C for 1.5 h to obtain the said SiO 2 modified Au / ZnO supported catalyst, in which the mass percentage of Au nanoparticles is 5.0 wt%, and the mass percentage of SiO 2 is 4.0 wt%. 2 2

[0065] Weigh 5 mg of the said catalyst and 10 g of solvent H 2 O and add them into a 50 mL high-pressure reactor. Adjust the magnetic stirrer speed to 1200 rpm, raise the reaction temperature to 60 °C, and introduce 3.0 MPa O 2 , 0.2 MPa CO and 0.8 MPa He. Stop the reaction after 5 min of reaction, conduct product detection, and the hydrogen peroxide generation rate is 9 mol H2O2 kg -1 h -1 .

[0066] Comparative Example 4

[0067] Measure 2.00 mL of HAuCl Au Au ·4H 2 4 O solution with a concentration of 5.00 mg 2 / mL and add it to a 500 mL beaker that has been pre-filled with 100 mL of deionized water; then add 0.99 g of ZnO powder with a specific surface area of 8 m 2 2 / g, and after vigorously stirring for 15 min; add a 0.5 mol / L ammonia precipitation agent and adjust to pH = 9.0 to obtain a precipitate; age it in a water bath at 80 °C for 1 h; then perform filtration and washing operations with 1.5 L of deionized water, and dry it in an oven at 60 °C for 12 h; subsequently, treat the dried product in a muffle furnace at 200 °C for 1.5 h to obtain the described Au / ZnO supported catalyst, and the mass percentage content of Au nanoparticles in this catalyst is 1.0 wt%.

[0068] Weigh 5 mg of the above catalyst and 10 g of solvent H 2 2 O and add them to a 50 mL autoclave. Adjust the magnetic stirrer speed to 1200 rpm, raise the reaction temperature to 60 °C, and introduce 3.0 MPa of O 2 2 , 0.2 MPa of CO, and 0.8 MPa of He. Stop the reaction after 5 min of reaction and perform product detection. The hydrogen peroxide generation rate is 51 mol H2O2 H2O2 kg -1 -1 h -1 -1 .

[0069] Although the present invention has been described with reference to the preferred embodiments, various modifications can be made to it and components therein can be replaced with equivalents without departing from the scope of the present invention. In particular, as long as there is no structural conflict, the technical features mentioned in each embodiment can be combined in any way. The present invention is not limited to the specific embodiments disclosed in the text, but includes all technical solutions falling within the scope of the claims.

Claims

1. A catalyst for synthesizing hydrogen peroxide, characterized in that: The catalyst is a silica-modified Au / ZnO supported catalyst, and the catalyst comprises metallic Au nanoparticles, ZnO and SiO 2 ; based on the mass of the catalyst, the content of Au nanoparticles is 0.1% to 3.0%, and the content of SiO 2 is 0.1% to 2.0%, and the content of ZnO is 95% to 99.8%; In the catalyst, the Au nanoparticles are wholly or partly wrapped by the SiO 2 layer; The preparation method of the catalyst comprises the following steps: 1) Mix a metal Au precursor solution with water to obtain solution I; 2) Add ZnO powder to solution I and stir to obtain mixture II; 3) Add tetraethyl orthosilicate to mixture II, stir, and then add a precipitant to adjust the pH to obtain a precipitate; 4) Age the precipitate obtained in step 3), then filter and wash to obtain a filter cake; 5) Dry and calcine the filter cake obtained in step 4) to obtain a catalyst for synthesizing hydrogen peroxide.

2. The catalyst according to claim 1, characterized in that: Based on the mass of the catalyst, the content of Au nanoparticles is 0.5% - 2.5%, and the content of SiO 2 is 0.2% - 2.0%.

3. The preparation method of the catalyst according to any one of claims 1-2, characterized in that: Comprises the following steps: 1) Mix a metal Au precursor solution with water to obtain solution I; 2) Add ZnO powder to solution I and stir to obtain mixture II; 3) Add tetraethyl orthosilicate to mixture II, stir, and then add a precipitant to adjust the pH to obtain a precipitate; 4) Age the precipitate obtained in step 3), then filter and wash to obtain a filter cake; 5) Dry and calcine the filter cake obtained in step 4) to obtain a catalyst for synthesizing hydrogen peroxide.

4. The method according to claim 3, characterized in that: In step 1), the metal Au precursor solution is selected from at least one of chloroauric acid tetrahydrate solution and chloroauric acid trihydrate solution; and / or, the concentration of the metal Au precursor solution is 2 to 15 mg Au / mL; And / or, the volume ratio of the gold precursor solution to water is 1:30 to 1:

80.

5. The method according to claim 3, characterized in that: In step (2), the specific surface area of the ZnO powder is 15 to 60 m 2 / g.

6. The method according to claim 3, characterized in that: In step 2), after adding ZnO powder, the stirring time is 10 to 30 min; in step 3), after adding tetraethyl orthosilicate, the stirring time is 5 to 30 min.

7. The method according to claim 3, characterized in that: In step 3), the precipitant is selected from at least one of ammonia water, ammonium carbonate or sodium hydroxide; the pH is adjusted to 7.0 to 9.

0.

8. The method according to claim 3, characterized in that: In step 4), the aging conditions are: aging at 30 to 80 °C for 1 to 5 h.

9. The method according to claim 3, characterized in that: In step 5), the drying conditions are: drying at 60 to 100 °C for 6 to 16 h; the calcination conditions are: calcination at 150 to 600 °C for 1 to 4 h.

10. Use of a catalyst according to any one of claims 1-2 or a catalyst prepared by the method according to any one of claims 3-9, said use being for reacting CO, O 2 and H 2 O as raw materials in the presence of said catalyst to prepare H 2 O 2 .

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