Catalyst for synthesizing hydrogen peroxide as well as preparation method and application of catalyst

Abstract

The invention relates to a catalyst for synthesizing hydrogen peroxide and a preparation method and application thereof. The catalyst comprises a carrier, a first active metal, a second active metal and a third active metal, the first active metal comprises W, the second active metal comprises Pd, and the third active metal comprises Au; the carrier comprises TiO2 and / or Al2O3. The catalyst particles are good in dispersity and uniform in size, and have good catalytic activity in direct synthesis of hydrogen peroxide.

Description

Technical Field

[0001] The present disclosure relates to the field of catalyst preparation, and in particular, to a catalyst for synthesizing hydrogen peroxide and a preparation method and application thereof. Background Art

[0002] As a green oxidant, hydrogen peroxide (H2O2) is widely used in the selective oxidation of olefins, water purification, pulp bleaching and pharmaceutical sterilization. At present, hydrogen peroxide is mainly produced by the anthraquinone method, which uses an indirect process of hydrogenation and oxidation in sequence. It has the disadvantages of high energy consumption, high cost and high pollution in the production and product separation and purification process. The direct synthesis of hydrogen peroxide by hydrogen and oxygen has become a potential method for industrial production of H2O2 due to its advantages such as simple process, low energy consumption, low environmental pollution and on-site production and use. However, the main challenges currently faced by the direct synthesis of hydrogen peroxide in industrial applications are the low productivity and selectivity caused by side reactions such as the dissociation of O2 to form H2O, the decomposition of H2O2 and hydrogenation. Therefore, the development of efficient catalysts with high activity and excellent selectivity is a key issue for the further industrial application of the direct synthesis of hydrogen peroxide by hydrogen and oxygen.

[0003] In the direct synthesis of hydrogen peroxide from hydrogen and oxygen, the precious metal Pd is the most effective catalyst. However, the Pd monometallic catalyst will also promote the formation of the byproduct H2O, which greatly reduces the selectivity of H2O2. Hutchings et al. (Chem. Commun. 2002, 2058-2059) first reported that the PdAu bimetallic catalyst has a higher H2O2 selectivity than the Pd monometallic catalyst, which has aroused extensive research on the PdAu bimetallic catalyst. However, the high selectivity of the PdAu catalyst is often accompanied by a low H2 conversion rate, which limits its further industrial application. Summary of the invention

[0004] The purpose of the present disclosure is to provide a catalyst for synthesizing hydrogen peroxide, a preparation method and application thereof, wherein the catalyst particles have good dispersibility and uniform size and have good catalytic activity in the direct synthesis of hydrogen peroxide.

[0005] In order to achieve the above-mentioned objectives, the first aspect of the present disclosure provides a catalyst for synthesizing hydrogen peroxide, which comprises a carrier and a first active metal, a second active metal and a third active metal; the first active metal comprises W, the second active metal comprises Pd, and the third active metal comprises Au; the carrier comprises TiO2 and / or Al2O3.

[0006] Optionally, based on the total weight of the catalyst, the total content of the first active metal, the second active metal and the third active metal is 0.1 to 10% by weight, preferably 0.5 to 5% by weight;

[0007] Preferably, based on the total weight of the catalyst, the content of the first active metal is 0.01 to 9.98% by weight, the content of the second active metal is 0.01 to 9.99% by weight, and the content of the third active metal is 0.01 to 9.98% by weight; preferably, the content of the first active metal is 0.01 to 4.98% by weight, the content of the second active metal is 0.01 to 4.98% by weight, and the content of the third active metal is 0.01 to 4.98% by weight;

[0008] Optionally, the weight ratio of the first active metal: the second active metal: the third active metal is 0.01-10: 1: 0.01-20; preferably 0.1-5: 1: 0.5-10.

[0009] A second aspect of the present disclosure provides a method for preparing a catalyst for synthesizing hydrogen peroxide, comprising the following steps:

[0010] S1, contacting a support with a first solution to perform a first loading treatment to obtain a first product; wherein the first solution comprises a first active metal precursor, and the first active metal precursor comprises a W precursor;

[0011] S2, subjecting the first product to a first calcination treatment to obtain a second product;

[0012] S3, contacting the second product with a second solution for a second loading treatment to obtain a third product; wherein the second solution comprises a second active metal precursor and a third active metal precursor, the second active metal precursor comprises a Pd precursor, and the third active metal precursor comprises an Au precursor;

[0013] S4, subjecting the third product to a second calcination treatment.

[0014] Optionally, in step S1, the carrier is selected from one or both of TiO2 and Al2O3;

[0015] The W precursor is selected from one or both of ammonium metatungstate and sodium tungstate;

[0016] Preferably, the weight ratio of the first active metal precursor to the carrier is 0.0016 to 0.16:1, preferably 0.0016 to 0.08:1;

[0017] Optionally, the solvent of the first solution is selected from one or more of water and alcohol compounds; optionally, the alcohol compound includes ethanol;

[0018] Preferably, the concentration of the first active metal precursor in the first solution is 0.001 to 0.1 g / mL, preferably 0.005 to 0.05 g / mL.

[0019] Optionally, in step S2, the conditions of the first calcination treatment include: under static air, the calcination temperature is 200-1000° C., the calcination time is 1-10 hours, and the calcination pressure is 0.1-1 MPa; preferably, the calcination temperature is 400-600° C., the calcination time is 2-4 hours, and the calcination pressure is 0.1-0.5 MPa;

[0020] Optionally, the temperature rising gradient of the first calcination treatment is 2 to 20° C. / min, preferably 5 to 10° C. / min.

[0021] Optionally, in step S3, the Pd precursor is selected from one or more of chloropalladic acid, sodium tetrachloropalladate and palladium acetylacetonate;

[0022] The Au precursor is selected from one or more of chloroauric acid and sodium gold thiosulfate;

[0023] Preferably, in the second solution, the concentration of the Pd precursor is 1 to 100 mg / mL, preferably 4 to 60 mg / mL; the concentration of the Au precursor is 1 to 100 mg / mL, preferably 5 to 50 mg / mL;

[0024] Optionally, the weight ratio of the total weight of the Pd precursor and the Au precursor to the second product is 0.001 to 0.3:1, preferably 0.1 to 0.3:1.

[0025] Optionally, in step S4, the conditions of the second calcination treatment include:

[0026] In a hydrogen atmosphere, first purge at 0-100°C for 30-240 minutes, then heat to 200-1000°C and calcine for 2-10 hours; preferably, first purge at 0-50°C for 60-120 minutes, then heat to 400-600°C and calcine for 2-4 hours;

[0027] Optionally, the temperature rise gradient is 2 to 50°C / min, preferably 5 to 20°C / min;

[0028] Optionally, the purge gas for the second calcination treatment further comprises an inert gas, and the inert gas is selected from one or more of argon and nitrogen; preferably, the volume content of hydrogen is 5 to 25 volume % based on the total volume of the purge gas.

[0029] A third aspect of the present disclosure provides a catalyst for synthesizing hydrogen peroxide prepared by the method described in the second aspect of the present disclosure.

[0030] The fourth aspect of the present disclosure provides use of the catalyst described in the first aspect and the third aspect of the present disclosure in the direct synthesis of hydrogen peroxide from hydrogen and oxygen.

[0031] Optionally, the method comprises the following steps: mixing the catalyst with a reaction solvent to obtain a catalyst mixture material; then introducing hydrogen and oxygen into the catalyst mixture material in a reaction container to perform a direct synthesis of hydrogen peroxide reaction;

[0032] Optionally, the reaction solvent is selected from one or more of concentrated sulfuric acid, methanol, ethanol and water;

[0033] Preferably, the conditions for the direct synthesis of hydrogen peroxide reaction include: reaction temperature of -10 to 20°C, preferably 0 to 10°C; reaction time of 0.1 to 5h, preferably 0.1 to 1h; reaction pressure of 1 to 20MPa, preferably 1 to 10MPa; molar ratio of hydrogen to oxygen of 1:0.01 to 10.0, preferably 1:0.1 to 5.0.

[0034] Through the above technical scheme, the present disclosure provides a catalyst for synthesizing hydrogen peroxide, a preparation method and application thereof. The catalyst provided by the present disclosure includes three metals, Pd, Au and W, and exhibits better catalytic activity and selectivity than traditional PdAu bimetallic catalysts in the direct synthesis of hydrogen peroxide from hydrogen and oxygen; the catalyst provided by the present disclosure uses non-precious metal W as the doping metal, which reduces the cost of the catalyst; the catalyst particles provided by the present disclosure have good dispersibility and uniform size; the catalyst preparation process is simple, and has good application prospects in the field of catalysis.

[0035] Other features and advantages of the present disclosure will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The accompanying drawings are used to provide a further understanding of the present disclosure and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present disclosure but do not constitute a limitation of the present disclosure. In the accompanying drawings:

[0037] Figure 1 TEM image of the supported PdAuW tri-metallic nanocatalyst prepared in Example 1;

[0038] Figure 2 This is a particle size distribution diagram of the supported PdAuW tri-metallic nanocatalyst prepared in Example 1;

[0039] Figure 3 This is a line scan of the supported PdAuW tri-metallic nanocatalyst prepared in Example 1;

[0040] Figure 4 This is the mapping diagram of the supported PdAuW tri-metallic nanocatalyst prepared in Example 1;

[0041] Figure 5This is the XRD pattern of the supported PdAuW tri-metal nanocatalyst prepared in Example 1. DETAILED DESCRIPTION

[0042] The specific embodiments of the present disclosure are described in detail below. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present disclosure, and are not used to limit the present disclosure.

[0043] In a first aspect, the present disclosure provides a catalyst for synthesizing hydrogen peroxide, comprising a carrier and a first active metal, a second active metal and a third active metal; the first active metal comprises W, the second active metal comprises Pd, and the third active metal comprises Au; and the carrier comprises TiO2 and / or Al2O3.

[0044] The present disclosure provides a catalyst for synthesizing hydrogen peroxide, a preparation method thereof, and an application thereof. The catalyst provided by the present disclosure comprises three metals, Pd, Au, and W, and exhibits better catalytic activity and selectivity than a PdAu bimetallic catalyst in the direct synthesis of hydrogen peroxide from hydrogen and oxygen; the catalyst uses non-precious metal W as a doping metal, thereby reducing the cost of the catalyst; the catalyst particles provided by the present disclosure have good dispersibility and are uniform in size.

[0045] In one embodiment, based on the total weight of the catalyst, the total content of the first active metal, the second active metal and the third active metal is 0.1 to 10% by weight, preferably 0.5 to 5% by weight; the rest is the carrier. The catalyst has an optimized content range in this embodiment, and the catalyst has a better catalytic effect for synthesizing hydrogen peroxide.

[0046] In a specific embodiment, based on the total weight of the catalyst, the content of the first active metal is 0.01-9.98% by weight, the content of the second active metal is 0.01-9.99% by weight, and the content of the third active metal is 0.01-9.98% by weight; preferably, the content of the first active metal is 0.01-4.98% by weight, the content of the second active metal is 0.01-4.98% by weight, and the content of the third active metal is 0.01-4.98% by weight;

[0047] Optionally, the molar weight ratio of the first active metal: the second active metal: the third active metal is 0.01-10: 1: 0.01-20; preferably 0.1-5: 1: 0.5-10. The catalyst has the content of active metal optimized in the present embodiment, and the catalyst has better catalytic activity and selectivity in the direct synthesis of hydrogen peroxide from hydrogen and oxygen. In the present disclosure, the content of active metal is obtained by X-ray fluorescence spectroscopy (XRF) test.

[0048] A second aspect of the present disclosure provides a method for preparing a catalyst for synthesizing hydrogen peroxide, comprising the following steps:

[0049] S1, contacting a support with a first solution to perform a first loading treatment to obtain a first product; wherein the first solution comprises a first active metal precursor, and the first active metal precursor comprises a W precursor;

[0050] S2, subjecting the first product to a first calcination treatment to obtain a second product;

[0051] S3, contacting the second product with a second solution for a second loading treatment to obtain a third product; wherein the second solution comprises a second active metal precursor and a third active metal precursor, the second active metal precursor comprises a Pd precursor, and the third active metal precursor comprises an Au precursor;

[0052] S4, subjecting the third product to a second calcination treatment.

[0053] The present disclosure provides a method for preparing a catalyst, wherein a carrier is first contacted with a W precursor for W loading treatment, and then Pd and Au are loaded simultaneously, wherein the active components of the catalyst are evenly distributed without agglomerated large particles; the preparation method is simple in process and has good application prospects in the field of catalysis.

[0054] In one embodiment, in step S1, the carrier is selected from one or both of TiO2 and Al2O3. The type of carrier in this embodiment can achieve a better W loading effect. If other carriers are selected, the interaction between W and the carrier will cause the incorporation of W to fail to play a positive role.

[0055] In one embodiment, the W precursor is selected from ammonium metatungstate ((NH4)6H2W 12 O 40 xH2O, "xH2O" represents the state of ammonium metatungstate hydrate, x has no specific value) and sodium tungstate, one or both; preferably ammonium metatungstate. The W precursor provided in this embodiment is used to disperse the active metal more evenly on the carrier, thereby improving the catalytic performance of the catalyst in the direct synthesis of hydrogen peroxide.

[0056] In a preferred embodiment, the weight ratio of the first active metal precursor to the carrier is 0.0016 to 0.16:1, preferably 0.0016 to 0.08:1;

[0057] Optionally, the solvent of the first solution is selected from one or more of water and alcohol compounds; optionally, the alcohol compound includes ethanol;

[0058] Preferably, the concentration of the first active metal precursor in the first solution is 0.001 to 0.1 g / mL, preferably 0.005 to 0.05 g / mL.

[0059] In a specific implementation manner, before step S1, the method further includes:

[0060] The first active metal precursor is mixed with a solvent and ultrasonically dissolved to form a first solution; and the carrier is placed in an appropriate amount of deionized water and stirred at room temperature to uniformly disperse the carrier. The ultrasonic dissolution uses a conventional ultrasonic device in the art. The stirring time can be 0.2 to 3 hours. The carrier can be fully dispersed by stirring.

[0061] In a specific embodiment, step S1 includes: slowly dropping the first solution into the carrier, stirring at room temperature, so that the precursor is evenly loaded on the carrier to obtain a mixed solution; wherein the stirring time can be 0.25 to 24 hours, and the metal can be evenly loaded on the carrier by stirring. If the stirring time is too short, it is difficult to fully load.

[0062] In a specific embodiment, the method further includes: placing the mixed solution in a water bath, evaporating and collecting the solid, drying and grinding the solid to obtain the first product. The stirring speed of the water bath can be 400-800r / min, and the stirring temperature is 80-95°C; a low stirring rate and a low temperature will cause the water to evaporate too slowly; while a stirring rate that is too fast or a temperature that is too high will cause the liquid to evaporate too quickly, affecting the distribution of the metal on the carrier. Preferably, the drying condition is 80-110°C for 12-24h. If the drying time is too short or the temperature is too low, the water will not be completely dried, affecting the subsequent calcination, while a drying temperature that is too high will affect the distribution of the metal on the carrier.

[0063] In one embodiment, in step S2, the conditions of the first calcination treatment include: under static air, the calcination temperature is 200-1000° C., the calcination time is 1-10 hours, and the calcination pressure is 0.1-1 MPa; preferably, the calcination temperature is 400-600° C., the calcination time is 2-4 hours, and the calcination pressure is 0.1-0.5 MPa;

[0064] Optionally, the temperature rising gradient of the first calcination treatment is 2 to 20°C / min, preferably 5 to 10°C / min. If the heating rate is too slow, the nanoparticles are easy to agglomerate; if the heating rate is too fast, the nanoparticles will be heated unevenly, the size distribution will be too wide, and the power of the tube furnace will increase too quickly, which will reduce the service life of the resistance wire. In addition, if the calcination temperature is too low or the time is too short, the metal salt in the sample will not be decomposed and impurities will be present. Conversely, if the temperature is too high or the time is too long, the nanoparticles will agglomerate, and the particle composition and structure cannot be fixed. According to the preferred conditions of the first calcination treatment in this embodiment, a better catalyst effect can be obtained.

[0065] In one embodiment, in step S3, the Pd precursor is selected from one or more of chloropalladic acid, sodium tetrachloropalladate and palladium acetylacetonate;

[0066] The Au precursor is selected from one or more of chloroauric acid and tetrabutylammonium tetrachloroaurate;

[0067] Preferably, in the second solution, the concentration of the Pd precursor is 1 to 100 mg / mL, preferably 4 to 60 mg / mL; the concentration of the Au precursor is 1 to 100 mg / mL, preferably 5 to 50 mg / mL; optionally, the weight ratio of the total weight of the Pd precursor and the Au precursor to the second product is 0.001 to 0.1:1, preferably 0.01 to 0.1; the weight ratio of the Pd precursor to the Au precursor is 1:0.1 to 10, preferably 1:0.5 to 5. The catalyst is prepared according to the preferred raw material dosage in this embodiment, which can further improve the catalytic effect of the obtained catalyst in the direct synthesis of hydrogen peroxide from hydrogen and oxygen.

[0068] In one embodiment, in step S4, the conditions of the second calcination treatment include:

[0069] In a hydrogen atmosphere, first purge at 0-100°C for 30-240 minutes, then heat to 200-1000°C and calcine for 2-10 hours; preferably, first purge at 0-50°C for 60-120 minutes, then heat to 400-600°C and calcine for 2-4 hours; the purge time should ensure that there is no air in the quartz tube;

[0070] Optionally, the temperature gradient is 2 to 50° C. / min, preferably 5 to 20° C. / min. The second calcination treatment is carried out under the conditions of this embodiment to perform activation pretreatment on the catalyst, which can improve the catalytic performance.

[0071] In a specific embodiment, the purge gas for the second calcination treatment further comprises an inert gas, and the inert gas is selected from one or more of argon and nitrogen; preferably, the volume content of hydrogen is 5 to 25 volume % based on the total volume of the purge gas.

[0072] A third aspect of the present disclosure provides a catalyst for synthesizing hydrogen peroxide prepared by the method described in the second aspect of the present disclosure.

[0073] The fourth aspect of the present disclosure provides use of the catalyst described in the first aspect and the third aspect of the present disclosure in the direct synthesis of hydrogen peroxide from hydrogen and oxygen.

[0074] In a specific embodiment, the method comprises the following steps: mixing the catalyst with a reaction solvent to obtain a catalyst mixture material; then introducing hydrogen and oxygen into the catalyst mixture material in a reaction container to perform a direct hydrogen peroxide synthesis reaction;

[0075] Optionally, the reaction solvent is selected from one or more of concentrated sulfuric acid, methanol, ethanol and water;

[0076] Preferably, the conditions for the direct synthesis of hydrogen peroxide reaction include: a reaction temperature of -10 to 20°C, preferably 0 to 10°C; a reaction time of 0.1 to 5h, preferably 0.1 to 1h; a reaction pressure of 1 to 20MPa, preferably 1 to 10MPa; and a hydrogen to oxygen usage ratio of 0.1 to 5:1:0.5 to 10 based on the operating pressure of hydrogen and oxygen.

[0077] Any range recited in the present disclosure includes any numerical value between the end values ​​and any sub-range formed by the end values ​​or any numerical value between the end values.

[0078] Unless otherwise specified, all raw materials in the present disclosure can be obtained through commercial purchase, and the equipment used in the present disclosure can adopt conventional equipment in the relevant field or refer to the existing technology in the relevant field.

[0079] The present disclosure is further described in detail by way of examples. The raw materials used in the examples can all be obtained through commercial sources.

[0080] The TEM photos, line scans, and mapping images of the samples were all taken using a Phillips FEI Tecnai 30 transmission electron microscope. The size and distribution of the metal nanoparticles were analyzed using ImageJ software. The specific method is as follows: In the electron microscope image with a suitable magnification, no less than 300 metal particles were randomly selected, their diameters were measured, and the particle size distribution of the sample was obtained. The calculation formula is as follows:

[0081]

[0082] In formula (1): d i is the measured particle diameter; n i It is the percentage of particles at each particle size value in the total particles.

[0083] The XRD pattern of the sample was tested using a Philips PANAlytical X'Pert Pro rotating target X-ray powder diffractometer.

[0084] The component contents of the samples were measured by X-ray fluorescence spectrometer (Bruker S8 TIGER analyzer).

[0085] Example 1

[0086] A method for preparing a supported PdAuW trimetallic nanocatalyst for direct synthesis of hydrogen peroxide comprises the following steps:

[0087] (1) Weigh 3.83 mg (NH4)6H2W in beaker 1 12 O 40 ·xH2O) was dissolved in 4 mL of deionized water and ultrasonicated for 10 min to dissolve the metal salt. The concentration of the W metal precursor was 0.9575 mg / mL;

[0088] (2) 920 mg TiO2 was weighed into beaker 2 and dispersed in 10 mL deionized water, ultrasonically dispersed, and stirred at room temperature for 10 min;

[0089] (3) During the stirring process, the W precursor solution was slowly dripped into TiO2 and the stirring was continued for 15 minutes to make it evenly loaded on the carrier to obtain a mixed solution, and the weight ratio of the first active metal precursor to the carrier was 0.004163:1;

[0090] (4) placing it in a water bath, setting the temperature to 80°C, stirring at a speed of 600 r / min, stirring until the water evaporates, and then placing it in a drying oven for drying at 110°C for 16 h, and then grinding it into powder for later use;

[0091] (5) The powder was placed in a porcelain boat and calcined in a tubular furnace at 500°C for 3 h in static air. The calcination pressure was 0.1 MPa and the temperature gradient was 10°C / min. The powder was cooled to room temperature to obtain a W / TiO2 sample.

[0092] (6) 1.02 mL of 6.2 mg / mL HAuCl4 solution and 2.08 mL of 4.5 mg / mL H2PdCl4 solution were mixed and ultrasonicated for 10 min, and then added dropwise into a dispersion containing 0.595 gW / TiO2 dispersed in 5 mL H2O; the other steps were the same as steps (4) to (5), except that the calcination conditions in step (5) were changed to: purging at 50°C for 90 min under a 5 vol% H2 / Ar atmosphere, then heating to 400°C at a rate of 10°C / min, calcining for 3 h, and cooling to room temperature to obtain a supported PdAuW trimetallic nanocatalyst, denoted as A1.

[0093] Figure 1 The TEM image of the supported PdAuW trimetallic nanocatalyst obtained in this example shows that the catalyst particles have good dispersion and no agglomeration, and the average particle size of the metal particles in the catalyst is 3.3±0.1 nm.

[0094] Figure 2 The particle size distribution diagram of the supported PdAuW tri-metallic nanocatalyst obtained in this example is shown in FIG. The particle size distribution range of the catalyst is 1.85 to 14.9 nm, and the size distribution range is relatively small.

[0095] Figure 3 The line scan image of the supported PdAuW tri-metal nanocatalyst obtained in this example. The three metals Pd, Au and W are evenly distributed on the particles of the catalyst.

[0096] Figure 4 The mapping diagram of the supported PdAuW trimetallic nanocatalyst obtained in this example shows that the catalyst is a W-modified carrier loaded with PdAuW nanoparticles with large Au-rich particles and small Pd-rich particles.

[0097] Figure 5 The XRD pattern of the supported PdAuW trimetallic nanocatalyst obtained in this example shows the peaks of the supported TiO2 and Au in the XRD spectrum of the catalyst, but due to the small particle size, which is below the detection limit of XRD, the relevant peaks of Pd and W are not detected.

[0098] Comparative Example 1

[0099] Referring to the preparation method of Example 1, the difference from Example 1 is that the carrier is replaced by MgO, and the rest of the process is the same as Example 1. The obtained sample is recorded as D1.

[0100] Comparative Example 2

[0101] Referring to the preparation method of Example 1, the difference from Example 1 is that no metal W precursor is added, and only Pd and Au are loaded on the carrier. The obtained sample is recorded as D2.

[0102] Comparative Example 3

[0103] Referring to the preparation method of Example 1, the difference from Example 1 is that Au and Pd are first loaded on TiO2, and after calcination and reduction treatment, W is loaded. The obtained sample is recorded as D3.

[0104] Comparative Example 4

[0105] Referring to the preparation method of Example 1, the difference from Example 1 is that the W precursor is replaced by a sodium molybdate precursor, and the obtained sample is recorded as D4.

[0106] Example 2

[0107] This embodiment refers to the preparation method of embodiment 1, and the difference from embodiment 1 is that the Pd precursor chloropalladium acid (H2PdCl4) is replaced by acetylacetonate palladium (C 10 H 14 O4Pd4), and the rest of the process is the same as in Example 1, and the obtained sample is recorded as A2.

[0108] Example 3

[0109] This example refers to the preparation method of Example 1, and the difference from Example 1 is that the carrier TiO2 is replaced by Al2O3, and the rest of the process is the same as Example 1. The obtained sample is recorded as A3.

[0110] Example 4

[0111] This embodiment refers to the preparation method of embodiment 1, and the difference from embodiment 1 is that the W precursor ammonium metatungstate ((NH4)6H2W 12 O 40 ·xH2O) was replaced by sodium tungstate dihydrate (Na2WO4·2H2O), and the rest of the process was the same as in Example 1. The obtained sample was recorded as A4.

[0112] Example 5

[0113] This example refers to the preparation method of Example 1, and the difference from Example 1 is that the calcination temperature of the loaded W is changed from 400°C to 600°C, and the rest of the process is the same as Example 1. The obtained sample is recorded as A5.

[0114] Example 6

[0115] This example refers to the preparation method of Example 1, and the difference from Example 1 is that the Pd precursor chloropalladium acid (H2PdCl4) is replaced by palladium nitrate (Pd(NO3)2), and the rest of the process is the same as Example 1. The obtained sample is recorded as A6.

[0116] Example 7

[0117] Referring to the preparation method in Example 1, the difference from Example 1 is that: 1.3 mg (NH4)6H2W is weighed 12 O 40 ·xH2O, 0.18 mL of HAuCl4 solution with a concentration of 6.2 mg / mL, and 0.353 mL of H2PdCl4 solution with a concentration of 4.5 mg / mL; the rest of the process is the same as in Example 1, and the obtained sample is recorded as A7.

[0118] Example 8

[0119] Referring to the preparation method in Example 1, the difference from Example 1 is that: 15.1 mg (NH4)6H2W 12 O 40 ·xH2O, 0.305 mL of HAuCl4 solution with a concentration of 6.2 mg / mL, and 0.418 mL of H2PdCl4 solution with a concentration of 4.5 mg / mL; the rest of the process is the same as in Example 1, and the obtained sample is recorded as A8.

[0120] Example 9

[0121] Referring to the preparation method in Example 1, the difference from Example 1 is that: 3.83 mg (NH4)6H2W 12 O 40 ·xH2O (the weight ratio of the first active metal precursor to the carrier is 0.004:1), 0.18mL of HAuCl4 solution with a concentration of 6.2mg / mL (the effective mass of the Au metal precursor is 1.116mg), and 3.73mL of H2PdCl4 solution with a concentration of 4.5mg / mL; the rest of the process is the same as in Example 1, and the obtained sample is recorded as A9.

[0122] Example 10

[0123] Referring to the preparation method in Example 1, the difference from Example 1 is that:

[0124] The conditions of the first calcination treatment in step (5) are: calcination at 200° C. for 5 h in static air, a calcination pressure of 0.1 MPa, and a temperature gradient of 2° C. / min;

[0125] The conditions of the second calcination treatment in step (6) are: purging at 25°C for 50 min in a 5 vol% H2 / Ar atmosphere, then heating to 200°C at a heating rate of 50°C / min, and calcining for 5 h. The rest of the process is the same as in Example 1. The obtained sample is recorded as A10.

[0126] Embodiment 11

[0127] Referring to the preparation method in Example 1, the difference from Example 1 is that:

[0128] The conditions of the first calcination treatment in step (5) are: calcination at 1000° C. for 20 h in static air, a calcination pressure of 0.1 MPa, and a temperature gradient of 0.5° C. / min;

[0129] The conditions of the second calcination treatment in step (6) are: purging at 120°C for 20 min in a 5 vol% H2 / Ar atmosphere, then heating to 100°C at a heating rate of 100°C / min, and calcining for 1 h. The rest of the process is the same as in Example 1. The obtained sample is recorded as A11.

[0130] Example 12

[0131] Referring to the preparation method in Example 1, the difference from Example 1 is that:

[0132] The stirring and drying conditions in step (4) and step (6) are changed to:

[0133] In a water bath, the temperature was set to 110°C and the stirring speed was 100 r / min. The mixture was stirred until the water evaporated and then placed in a drying oven for drying. After drying at 130°C for 8 h, the mixture was ground into powder for later use. The rest of the process was the same as in Example 1. The obtained sample was recorded as A12.

[0134] The component contents of the catalysts prepared in the above examples and comparative examples are listed in the following Table 1.

[0135] Table 1

[0136]

[0137]

[0138] Test Example 1

[0139] This test example is used to illustrate the specific application of the catalyst prepared in the above embodiments and comparative examples in the direct synthesis of hydrogen peroxide from hydrogen and oxygen, comprising the following steps: the prepared catalyst (30 mg) is ultrasonically dispersed in a reaction solvent (0.15 mL of concentrated sulfuric acid, 56 g of methanol and 29 g of deionized water), then placed in a sealed autoclave, and 2.9 MPa of 5 volume % H2 / N2 and 1.1 MPa of 25 volume % O2 / N2 are introduced into the autoclave respectively; the synthesis reaction is carried out at 2°C and 4 MPa for 15 min. After the reaction is completed, the tail gas is discharged from the upper part of the reactor into a gas chromatograph to determine the hydrogen content in the tail gas, and then the reaction liquid is discharged and the hydrogen peroxide concentration is determined by the cerium titration method. The H2O2 yield is defined as the number of moles of H2O2 produced per kilogram of catalyst per hour. The H2 conversion rate, H2O2 selectivity and H2O2 yield are calculated according to the following formulas (2) to (4).

[0140]

[0141]

[0142]

[0143] The test results are listed in Table 2 below.

[0144] Table 2

[0145]

[0146] Test Examples 2-3

[0147] Referring to the reaction method in Test Example 1, the difference from Test Example 1 is that hydrogen peroxide is directly synthesized from hydrogen and oxygen according to the reaction conditions listed in Table 3 below. The reaction results are listed in Table 3 below.

[0148] Table 3

[0149]

[0150] In Table 3, the volume of hydrogen in the hydrogen mixture (H2 / N2) is 5% by volume, and the volume of oxygen in the oxygen mixture (O2 / N2) is 25% by volume.

[0151] The preferred embodiments of the present disclosure are described in detail above; however, the present disclosure is not limited to the specific details in the above embodiments. Within the technical concept of the present disclosure, a variety of simple modifications can be made to the technical solution of the present disclosure, and these simple modifications all fall within the protection scope of the present disclosure.

[0152] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present disclosure will not further describe various possible combinations.

[0153] In addition, various embodiments of the present disclosure may be arbitrarily combined, and as long as they do not violate the concept of the present disclosure, they should also be regarded as the contents disclosed by the present disclosure.

Claims

1. A catalyst for synthesizing hydrogen peroxide, characterized in that The catalyst comprises a carrier and a first active metal, a second active metal and a third active metal; the first active metal comprises W, the second active metal comprises Pd, and the third active metal comprises Au; and the carrier comprises TiO2 and / or Al2O3.

2. The catalyst according to claim 1, characterized in that Based on the total weight of the catalyst, the total content of the first active metal, the second active metal and the third active metal is 0.1 to 10% by weight, preferably 0.5 to 5% by weight; Preferably, based on the total weight of the catalyst, the content of the first active metal is 0.01 to 9.98% by weight, the content of the second active metal is 0.01 to 9.99% by weight, and the content of the third active metal is 0.01 to 9.98% by weight; preferably, the content of the first active metal is 0.01 to 4.98% by weight, the content of the second active metal is 0.01 to 4.98% by weight, and the content of the third active metal is 0.01 to 4.98% by weight; Optionally, the weight ratio of the first active metal: the second active metal: the third active metal is 0.01-10: 1: 0.01-20; preferably 0.1-5: 1: 0.5-10.

3. A method for preparing a catalyst for synthesizing hydrogen peroxide, characterized in that: The following steps are involved: S1, contacting the carrier with the first solution to perform a first loading treatment to obtain a first product; wherein the first solution comprises a first active metal precursor, and the first active metal precursor comprises a W precursor; S2, subjecting the first product to a first calcination treatment to obtain a second product; S3, contacting the second product with a second solution to perform a second loading treatment to obtain a third product; The second solution comprises a second active metal precursor and a third active metal precursor, the second active metal precursor comprises a Pd precursor, and the third active metal precursor comprises an Au precursor; S4, subjecting the third product to a second calcination treatment.

4. The method according to claim 3, characterized in that: In step S1, the carrier is selected from one or both of TiO2 and Al2O3; The W precursor is selected from one or both of ammonium metatungstate and sodium tungstate; Preferably, the weight ratio of the first active metal precursor to the carrier is 0.0016 to 0.16:1, preferably 0.0016 to 0.08:1; Optionally, the solvent of the first solution is selected from one or more of water and alcohol compounds; Optionally, the alcohol compound includes ethanol; Preferably, the concentration of the first active metal precursor in the first solution is 0.001-0.1 g / mL.

5. The method according to claim 3, characterized in that: In step S2, the conditions of the first calcination treatment include: under static air, the calcination temperature is 200-1000° C., the calcination time is 1-10 hours, and the calcination pressure is 0.1-1 MPa; preferably, the calcination temperature is 400-600° C., the calcination time is 2-4 hours, and the calcination pressure is 0.1-0.5 MPa; Optionally, the temperature rising gradient of the first calcination treatment is 2 to 20° C. / min, preferably 5 to 10° C. / min.

6. The method according to claim 3, characterized in that In step S3, the Pd precursor is selected from one or more of chloropalladic acid, sodium tetrachloropalladate and palladium acetylacetonate; The Au precursor is selected from one or more of chloroauric acid and sodium gold thiosulfate; Preferably, in the second solution, the concentration of the Pd precursor is 1 to 100 mg / mL, preferably 4 to 60 mg / mL; the concentration of the Au precursor is 1 to 100 mg / mL, preferably 5 to 50 mg / mL; Optionally, the weight ratio of the total weight of the Pd precursor and the Au precursor to the second product is 0.001-0.1:1, preferably 0.01-0.1:1; the weight ratio of the Pd precursor to the Au precursor is 1:0.1-10, preferably 1:0.5-5.

7. The method according to claim 3, characterized in that In step S4, the conditions of the second calcination treatment include: In a hydrogen atmosphere, first purge at 0-100°C for 30-240 minutes, then heat to 200-1000°C and calcine for 2-10 hours; preferably, first purge at 0-50°C for 60-120 minutes, then heat to 400-600°C and calcine for 2-4 hours; Optionally, the temperature rise gradient is 2 to 50°C / min, preferably 5 to 20°C / min; Optionally, the purge gas for the second calcination treatment further comprises an inert gas, and the inert gas is selected from one or more of argon and nitrogen; preferably, the volume content of hydrogen is 5 to 25 volume % based on the total volume of the purge gas.

8. A catalyst for synthesizing hydrogen peroxide prepared according to the method according to any one of claims 3 to 7.

9. Use of the catalyst according to any one of claims 1 to 2 and 8 in the direct synthesis of hydrogen peroxide from hydrogen and oxygen.

10. The use according to claim 9, characterized in that: The method comprises the following steps: mixing the catalyst with a reaction solvent to obtain a catalyst mixture material; then introducing hydrogen and oxygen into the catalyst mixture material in a reaction container to perform a direct hydrogen peroxide synthesis reaction; Optionally, the reaction solvent is selected from one or more of concentrated sulfuric acid, methanol, ethanol and water; Preferably, the conditions for the direct synthesis of hydrogen peroxide reaction include: a reaction temperature of -10 to 20°C, preferably 0 to 10°C; a reaction time of 0.1 to 5h, preferably 0.1 to 1h; a reaction pressure of 1 to 20MPa, preferably 1 to 10MPa; and a hydrogen to oxygen usage ratio of 0.01 to 10.0:1, preferably 0.01 to 5.0:1, based on the operating pressure of hydrogen and oxygen.

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