Encapsulated molecular sieve metal catalyst as well as preparation method and application thereof

Abstract

The invention discloses a packaged molecular sieve metal catalyst as well as a preparation method and application thereof. The encapsulated molecular sieve metal catalyst comprises a molecular sieve carrier and an active metal component, the active metal component is uniformly distributed in a pore channel or a cage-shaped structure of the molecular sieve carrier, and the active metal component is one or a combination of Pd and Au; the molecular sieve carrier is a titanium silicalite molecular sieve TS-1. The invention also discloses a preparation method of the catalyst. According to the catalyst, the mass transfer distance of hydrogen peroxide is shortened through the anchoring effect of the molecular sieve framework on the gold nanoparticles, agglomeration of metal particles is avoided, and the rate and efficiency of hydrogen peroxide in-situ synthesis and oxidation reaction are overall improved. When the encapsulated molecular sieve metal catalyst disclosed by the invention is applied to in-situ synthesis of hydrogen peroxide and cascade reaction for preparing ethylene glycol by oxidizing ethylene with hydrogen peroxide, the ethylene glycol generation rate can be # imgabs0 #

Description

Technical Field

[0001] The present invention belongs to the technical field of molecular sieve metal catalysts, and in particular relates to an encapsulated molecular sieve metal catalyst, a preparation method and applications thereof. Background Art

[0002] Oxidation of petroleum-based hydrocarbons to produce oxygenated organic compounds is an important route to high-value-added organic chemical raw materials and fine chemical products. In recent years, oxidation processes using hydrogen peroxide as an oxidant have seen rapid development, such as in the synthesis of chemicals like caprolactam and propylene oxide. Compared to traditional oxidants like oxygen and hypochlorite, hydrogen peroxide offers advantages such as mild reaction conditions, high selectivity, and low byproduct pollution. However, using hydrogen peroxide as an oxidant in industrial production presents a number of challenges that must be overcome. For example, production lines using hydrogen peroxide as an oxidant require an anthraquinone-based hydrogen peroxide synthesis unit, and the resulting high-concentration hydrogen peroxide needs to be diluted, further increasing production costs and energy consumption. Hydrogen peroxide is prone to inefficient decomposition during storage, transportation, and during the oxidation reaction, resulting in low hydrogen peroxide utilization. Halogens or acids must be added as decomposition inhibitors, which can cause corrosion to equipment. High-concentration hydrogen peroxide produced by the anthraquinone method is extremely hazardous during storage and transportation.

[0003] To address these issues, existing technologies integrate the production and use of hydrogen peroxide into a single reaction device. Using a catalyst composed of transition metal nanoparticles supported on a titanium silicalite molecular sieve, this technology achieves a tandem reaction process that couples the in-situ synthesis of hydrogen peroxide with the selective oxidation of hydrocarbons. This reduces the costs and risks associated with hydrogen peroxide production, storage, and transportation, while also improving hydrogen peroxide utilization. However, in this tandem reaction process, the performance of the catalyst supported by transition metal nanoparticles is poor. This is primarily due to the tendency of the metal nanoparticles to agglomerate during the preparation process, and the in-situ generated hydrogen peroxide needs to diffuse into the solution before contacting the titanium sites of the titanium silicalite molecular sieve for the next reaction. Summary of the Invention

[0004] The first technical problem addressed by the present invention is to provide an encapsulated molecular sieve metal catalyst. This catalyst shortens the mass transfer distance of hydrogen peroxide by anchoring gold nanoparticles within the molecular sieve framework. The high-strength molecular sieve framework prevents active metals from agglomerating and deactivating during catalyst preparation and use, maintaining a highly dispersed state of 2-5 nm. This overall improves the rate and efficiency of the in-situ hydrogen peroxide synthesis and oxidation reaction.

[0005] The second technical problem to be solved by the present invention is to provide a method for preparing an encapsulated molecular sieve metal catalyst.

[0006] The third technical problem to be solved by the present invention is to provide an application of an encapsulated molecular sieve metal catalyst in a catalyst for coupling the in-situ synthesis of hydrogen peroxide and the selective oxidation reaction of hydrocarbons as a series reaction.

[0007] In order to solve the above-mentioned first technical problem, the technical solution adopted by the present invention is as follows:

[0008] An encapsulated molecular sieve metal catalyst comprising:

[0009] Molecular sieve support and active metal component;

[0010] The active metal components are evenly distributed in the pores or cage structure of the molecular sieve carrier.

[0011] The active metal component is one of Pd and Au or a combination of the two;

[0012] The molecular sieve carrier is titanium silicalite molecular sieve TS-1.

[0013] Preferably, the active metal component accounts for 0.5-5.0 wt.% in the catalyst.

[0014] Preferably, the active metal component further includes one or more of Fe, Co, Ni, and Sn.

[0015] Preferably, the active metal component is a metal cluster or metal nanoparticles; the size of the active metal component particles is 0.5 to 3 nm.

[0016] In order to solve the above second technical problem, the technical solution adopted by the present invention is as follows:

[0017] A method for preparing an encapsulated molecular sieve metal catalyst comprises the following steps:

[0018] S1, forming a uniform and clear complex metal salt aqueous solution from an active metal precursor solution under the action of an organic ligand;

[0019] S2, mixing the complex metal salt aqueous solution with the mother liquor of the synthetic molecular sieve, and performing a hydrothermal reaction to obtain an intermediate product containing the molecular sieve;

[0020] S3. Collect the intermediate product by centrifugation or filtration, dry it, and perform high-temperature treatment to remove the residual template and organic ligand in the molecular sieve to obtain the molecular sieve-encapsulated metal catalyst.

[0021] Preferably, in step S1, the active metal precursor solution is one or both of nitrates and chlorides of active metals; and the active metal is one or both of Pd and Au.

[0022] Preferably, in step S1, the active metal further includes one or more of Fe, Co, Ni, and Sn.

[0023] Preferably, in step S1, the organic ligand is one or more of ammonia water, ethylenediamine, KH560, KH579, and KH590 (γ-mercaptopropyltrimethoxysilane).

[0024] Preferably, in step S2, the temperature of the hydrothermal reaction is 170-200° C., and the time is 3-96 hours.

[0025] Preferably, in step S3, the high temperature treatment is one of high temperature calcination and high temperature hydrogen reduction treatment.

[0026] The high-temperature calcination is carried out in an air atmosphere at a temperature of 300-800° C. and a time of 1-10 hours.

[0027] Preferably, the high-temperature hydrogen reduction treatment refers to a reduction temperature of 200-600° C. and a time of 1-6 h in a H 2 / N 2 atmosphere.

[0028] In order to solve the third technical problem mentioned above, the technical solution adopted by the present invention is as follows:

[0029] The invention discloses an application of an encapsulated molecular sieve metal catalyst as a catalyst for coupling the in-situ synthesis of hydrogen peroxide and the selective oxidation reaction of hydrocarbons as a series reaction.

[0030] Any range described in the present invention includes the end value and any numerical value between the end values ​​and any sub-range formed by the end value or any numerical value between the end values.

[0031] Unless otherwise specified, all raw materials in the present invention can be purchased commercially, and the equipment used in the present invention can adopt conventional equipment in the relevant field or refer to the existing technology in the relevant field.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] The present invention provides an encapsulated molecular sieve metal catalyst. This catalyst, through the anchoring effect of the molecular sieve framework on gold nanoparticles, shortens the mass transfer distance of hydrogen peroxide, prevents metal particle agglomeration, and overall improves the rate and efficiency of hydrogen peroxide in-situ synthesis and oxidation reactions. Testing has shown that when the weight proportion of the active metal component of the encapsulated molecular sieve metal catalyst of the present invention is ≥0.5wt.%, it is used in the tandem reaction of in-situ synthesis of hydrogen peroxide and oxidation of ethylene with hydrogen peroxide to produce ethylene glycol. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0035] Figure 1 is the XRD pattern of the encapsulated molecular sieve metal catalyst in Example 2 of the present invention;

[0036] Figure 2 is an FTIR graph of the encapsulated molecular sieve metal catalyst in Example 2 of the present invention;

[0037] Figure 3 This is the HAADF-STEM image of the encapsulated molecular sieve metal catalyst in Example 2 of the present invention. DETAILED DESCRIPTION

[0038] In order to explain the present invention more clearly, the present invention will be further described below in conjunction with preferred embodiments. It should be understood by those skilled in the art that the following specific description is illustrative rather than restrictive and should not be used to limit the scope of protection of the present invention.

[0039] As one aspect of the present invention, the present invention provides an encapsulated molecular sieve metal catalyst, comprising:

[0040] Molecular sieve support and active metal component;

[0041] The active metal components are evenly distributed in the pores or cage structure of the molecular sieve carrier.

[0042] The active metal component is one of Pd and Au or a combination of the two;

[0043] The molecular sieve carrier is titanium silicalite molecular sieve TS-1.

[0044] According to some embodiments of the present invention, the active metal component accounts for 0.5-5.0 wt.% in the catalyst.

[0045] According to some embodiments of the present invention, the active metal component further includes one or more of Fe, Co, Ni, and Sn.

[0046] According to some embodiments of the present invention, the active metal component is a metal cluster or metal nanoparticles; the size of the active metal component particles is 0.5-3 nm.

[0047] As another aspect of the present invention, a method for preparing an encapsulated molecular sieve metal catalyst comprises the following steps:

[0048] S1, forming a uniform and clear complex metal salt aqueous solution from an active metal precursor solution under the action of an organic ligand;

[0049] S2, mixing the complex metal salt aqueous solution with the mother liquor of the synthetic molecular sieve, and performing a hydrothermal reaction to obtain an intermediate product containing the molecular sieve;

[0050] S3. Collect the intermediate product by centrifugation or filtration, dry and treat it at high temperature to remove the residual template and organic ligand in the molecular sieve, and decompose the metal salt to generate nanoparticles during the roasting stage, ensuring that the nanoparticles are evenly distributed inside the molecular sieve crystals to obtain the molecular sieve encapsulated metal catalyst.

[0051] According to some embodiments of the present invention, in step S1, the active metal precursor solution is one or both of nitrates and chlorides of active metals; and the active metal is one or both of Pd and Au.

[0052] According to some embodiments of the present invention, in step S1, the active metal further includes one or more of Fe, Co, Ni, and Sn.

[0053] According to some embodiments of the present invention, in step S1, the organic ligand is one or more of ammonia water, ethylenediamine, KH560, KH579, and KH590 (γ-mercaptopropyltrimethoxysilane).

[0054] According to certain embodiments of the present invention, in step S2, the temperature of the hydrothermal reaction is 170-200° C., and the time is 6-96 hours.

[0055] According to some embodiments of the present invention, in step S3, the high-temperature treatment is one of high-temperature calcination and high-temperature hydrogen reduction treatment.

[0056] According to certain embodiments of the present invention, the high-temperature calcination is carried out in an air atmosphere, and the temperature of the high-temperature calcination is 300-800°C, for example, including but not limited to 350-800°C, 400-800°C, 450-800°C, 500-800°C, 550-800°C, 600-800°C, 650-800°C, 700-800°C, 750-800°C; the time is 1-10h, for example, including but not limited to 2-10h, 3-10h, 4-10h, 5-10h, 6-10h, 7-10h, 8-10h, 9-10h.

[0057] According to certain embodiments of the present invention, the high-temperature hydrogen reduction treatment refers to a reduction temperature of 200-600° C. and a time of 1-6 hours in an H 2 / N 2 atmosphere.

[0058] As another aspect of the present invention, the present invention provides an encapsulated molecular sieve metal catalyst for use as a catalyst for coupling in-situ synthesis of hydrogen peroxide and selective oxidation of hydrocarbons as a series reaction.

[0059] The encapsulated molecular sieve metal catalyst of the present invention is used for in-situ synthesis of hydrogen peroxide and ethylene oxidation to prepare ethylene glycol Performance evaluation steps :

[0060] 1) The reaction is carried out in a high-pressure batch reactor;

[0061] 2) Weigh 0.1 g of the corresponding catalyst prepared in the Examples or Comparative Examples, disperse it in 50 ml of water using ultrasonic technology, and add it to the reactor;

[0062] 3) Fill the reactor with 0.5 MPa ethylene for three times to ensure that there is no air in the reactor, and then fill it with 0.5 MPa ethylene, 1.0 MPa 25% O2 / N2 and 2.5 MPa 5% H2 / N2 in sequence;

[0063] 4) Start stirring the reactor, set the speed to 600 r / min, and heat to 90° C. for 6 hours. After the reaction is completed, start the circulating cooling water cooling system of the equipment to quickly reduce the reactor temperature to terminate the reaction. When the temperature drops to 30° C., remove the solution in the kettle and detect the amount of ethylene glycol generated in the solution by gas chromatography. The ethylene glycol production is analyzed by gas chromatography equipped with an FID detector. The calculation formula is as follows:

[0064]

[0065] Example 1

[0066] A method for preparing a TS-1 molecular sieve encapsulated Au nanoparticle catalyst comprises the following steps:

[0067] (1) Weigh 5.7 g of 2 mol in 500 mL H2O TPAOH solution and place it in a round-bottom flask. Control the water bath temperature to 30 °C and stir at 600 rpm. Add 200 μL of KH590 and 0.18 mL of 12.5 mg / mL Au solution and continue stirring for 30 min.

[0068] (2) Add 7.5 g of TEOS to the flask and stir to hydrolyze for 12 h. Add 0.32 g of TBOT to 1.3 g of IPA, dissolve to form a clear solution, and then add it dropwise to the flask. Adjust the water bath temperature to 50°C and continue stirring for 3 h.

[0069] (3) The water bath was heated to 70°C and the alcohol was removed for 1 hour. The resulting solution was diluted to 30 mL and then crystallized in a 50 mL hydrothermal reactor at 170°C for 72 hours. The resulting solid was collected, centrifuged, washed, and dried to obtain the catalyst precursor. The washing process was performed by washing twice with water and once with ethanol. The drying operation was performed in a forced air drying oven at 120°C for 12 hours.

[0070] (4) The dried catalyst was collected and ground, and then calcined in a tube furnace at 550°C for 6 h to obtain the final catalyst. The heating rate of the tube furnace was 10°C / min.

[0071] When the catalyst prepared in Example 1 was applied to the series reaction of ethylene oxide with hydrogen peroxide to prepare ethylene glycol using the above-mentioned performance evaluation steps of the present invention, the ethylene glycol production rate was shown in Table 1 below.

[0072] Example 2

[0073] A method for preparing a TS-1 molecular sieve encapsulated Au nanoparticle catalyst comprises the following steps:

[0074] (1) Weigh 5.7 g of 2 mol in 500 mL H2O TPAOH solution and place it in a round-bottom flask. Control the water bath temperature to 30 °C and stir at 600 rpm. Add 200 μL of KH590 and 1.8 mL of 12.5 mg / mL Au solution and continue stirring for 30 min.

[0075] (2) Add 7.5 g of TEOS to the flask and stir to hydrolyze for 12 h. Add 0.32 g of TBOT to 1.3 g of IPA, dissolve to form a clear solution, and then add it dropwise to the flask. Adjust the water bath temperature to 50°C and continue stirring for 3 h.

[0076] (3) The water bath was heated to 70°C and the alcohol was removed for 1 hour. The resulting solution was diluted to 30 mL and then crystallized in a 50 mL hydrothermal reactor at 180°C for 72 hours. The resulting solid was collected, centrifuged, washed, and dried to obtain the catalyst precursor. The washing process was performed by washing twice with water and once with ethanol. Drying was performed in a forced air drying oven at 120°C for 12 hours.

[0077] (4) The dried catalyst was collected and ground, and then calcined in a tube furnace at 550°C for 6 h to obtain the final catalyst. The heating rate of the tube furnace was 10°C / min.

[0078] Figure 1 is the XRD pattern of the encapsulated molecular sieve metal catalyst in Example 2 of the present invention;

[0079] Figure 2 is a TEM image of the encapsulated molecular sieve metal catalyst in Example 2 of the present invention;

[0080] Figure 3 This is the HAADF-STEM image of the encapsulated molecular sieve metal catalyst in Example 2 of the present invention.

[0081] When the catalyst prepared in Example 2 was applied to the tandem reaction of ethylene oxide with hydrogen peroxide to prepare ethylene glycol using the above-mentioned performance evaluation steps of the present invention, the ethylene glycol production rate was shown in Table 1 below.

[0082] Example 3

[0083] A method for preparing a TS-1 molecular sieve encapsulated Au nanoparticle catalyst comprises the following steps:

[0084] (1) Weigh 5.7 g of 2 mol in 500 mL H2O TPAOH solution and place it in a round-bottom flask. Control the water bath temperature to 30 °C and stir at 600 rpm. Add 200 μL of KH590 and 4.5 mL of 12.5 mg / mL Au solution and continue stirring for 30 min.

[0085] (2) Add 7.5 g of TEOS to the flask and stir to hydrolyze for 12 h. Add 0.32 g of TBOT to 1.3 g of IPA, dissolve to form a clear solution, and then add it dropwise to the flask. Adjust the water bath temperature to 50°C and continue stirring for 3 h.

[0086] (3) The water bath was heated to 70°C and the alcohol was removed for 1 hour. The resulting solution was diluted to 30 mL and then crystallized in a 50 mL hydrothermal reactor at 190°C for 72 hours. The resulting solid was collected, centrifuged, washed, and dried to obtain the catalyst precursor. The washing process was performed by washing twice with water and once with ethanol. Drying was performed in a forced air drying oven at 120°C for 12 hours.

[0087] (4) The dried catalyst was collected and ground, and then calcined in a tube furnace at 550°C for 6 h to obtain the final catalyst. The heating rate of the tube furnace was 10°C / min.

[0088] When the catalyst prepared in Example 3 was applied to the tandem reaction of ethylene oxide with hydrogen peroxide to prepare ethylene glycol using the above-mentioned performance evaluation steps of the present invention, the ethylene glycol production rate was shown in Table 1 below.

[0089] Example 4

[0090] A method for preparing a TS-1 molecular sieve encapsulated PdAu nanoparticle catalyst comprises the following steps:

[0091] (1) Weigh 5.7 g of 2 mol in 500 mL H2O TPAOH solution and place it in a round-bottom flask. Control the water bath temperature to 30 °C and stir at 600 rpm. Add 200 μL KH590, 0.9 mL 12.5 mg / mL Au solution, and 2.8 mL 4 mg / mL Pd 2+ The solution was stirred continuously for 30 min.

[0092] (2) Add 7.5 g of TEOS to the flask and stir to hydrolyze for 12 h. Add 0.32 g of TBOT to 1.3 g of IPA, dissolve to form a clear solution, and then add it dropwise to the flask. Adjust the water bath temperature to 50°C and continue stirring for 3 h.

[0093] (3) The water bath was heated to 70°C and the alcohol was removed for 1 hour. The resulting solution was diluted to 30 mL and then crystallized in a 50 mL hydrothermal autoclave at 200°C for 72 hours. The resulting solid was collected, centrifuged, washed, and dried to obtain the catalyst precursor. The washing process was performed by washing twice with water and once with ethanol. The catalyst precursor was dried in a forced air drying oven at 120°C for 12 hours.

[0094] (4) The dried catalyst was collected and ground, and then calcined in a tube furnace at 550°C for 6 h to obtain the final catalyst. The heating rate of the tube furnace was 10°C / min.

[0095] When the catalyst prepared in Example 4 was applied to the tandem reaction of ethylene oxide with hydrogen peroxide to prepare ethylene glycol using the above-mentioned performance evaluation steps of the present invention, the ethylene glycol production rate was shown in Table 1 below.

[0096] Example 5

[0097] A method for preparing a TS-1 molecular sieve encapsulated NiAu nanoparticle catalyst comprises the following steps:

[0098] (1) Weigh 95 mg of NiCl2·6H2O and dissolve it in 5 mL of H2O and stir for 10 minutes.

[0099] (2) Weigh 5.7 g of 2 mol in 500 mL H2O TPAOH solution and place it in the round-bottom flask containing the solution from step (1). Control the water bath temperature to 30°C and stir at 600 rpm. Add 200 μL of KH590 and 1.8 mL of 12.5 mg / mL Au solution and continue stirring for 30 min.

[0100] (2) Add 7.5 g of TEOS to the flask and stir to hydrolyze for 12 h. Add 0.32 g of TBOT to 1.3 g of IPA, dissolve to form a clear solution, and then add it dropwise to the flask. Adjust the water bath temperature to 50°C and continue stirring for 3 h.

[0101] (3) The water bath was heated to 70°C and the alcohol was removed for 1 hour. The resulting solution was diluted to 30 mL and then crystallized in a 50 mL hydrothermal reactor at 170°C for 72 hours. The resulting solid was collected, centrifuged, washed, and dried to obtain the catalyst precursor. The washing process was performed by washing twice with water and once with ethanol. Drying was performed in a forced air drying oven at 120°C for 12 hours.

[0102] (4) The dried catalyst was collected and ground, and then calcined in a tube furnace at 550°C for 6 h to obtain the final catalyst. The heating rate of the tube furnace was 10°C / min.

[0103] Using the above-mentioned performance evaluation steps of the present invention, when the catalyst prepared in Example 5 was applied to the series reaction of ethylene oxide with hydrogen peroxide to prepare ethylene glycol, the ethylene glycol production rate is shown in Table 1 below.

[0104] Example 6

[0105] A method for preparing a TS-1 molecular sieve encapsulated FeAu nanoparticle catalyst comprises the following steps:

[0106] (1) Weigh 163.8 mg of Fe(NO3)3·9H2O and dissolve it in 5 mL of H2O and stir for 10 min;

[0107] (2) Weigh 5.7 g of 2 mol in 500 mL H2O TPAOH solution and place it in the round-bottom flask containing the solution from step (1). Control the water bath temperature to 30°C and stir at 600 rpm. Add 200 μL of KH590 and 1.8 mL of 12.5 mg / mL Au solution and continue stirring for 30 min.

[0108] (3) Add 7.5 g of TEOS to the flask and stir to hydrolyze for 12 h. Add 0.32 g of TBOT to 1.3 g of IPA, dissolve to form a clear solution, and then add it dropwise to the flask. Adjust the water bath temperature to 50°C and continue stirring for 3 h.

[0109] (4) The water bath was heated to 70°C and the alcohol was removed for 1 hour. The resulting solution was diluted to 30 mL and then crystallized in a 50 mL hydrothermal reactor at 170°C for 72 hours. The resulting solid was collected, centrifuged, washed, and dried to obtain the catalyst precursor. The washing process was performed by washing twice with water and once with ethanol. Drying was performed in a forced air drying oven at 120°C for 12 hours.

[0110] (5) The dried catalyst was collected and ground, and then calcined in a tube furnace at 550 °C for 6 h to obtain the final catalyst. The heating rate of the tube furnace was 10 °C / min.

[0111] When the catalyst prepared in Example 6 was applied to the tandem reaction of ethylene oxide with hydrogen peroxide to prepare ethylene glycol using the above-mentioned performance evaluation steps of the present invention, the ethylene glycol production rate was shown in Table 1 below.

[0112] Example 7

[0113] A method for preparing a TS-1 molecular sieve encapsulated Au nanoparticle catalyst comprises the following steps:

[0114] (1) Weigh 5.7 g of 2 mol in 500 mL H2O TPAOH solution and place it in a round-bottom flask. Control the water bath temperature to 30 °C and stir at 600 rpm. Add 200 μL of ethylenediamine, 0.9 mL of 12.5 mg / mL Au solution, and 2.8 mL of 4 mg / mL Pd. 2+ The solution was stirred continuously for 30 min.

[0115] (2) Add 7.5 g of TEOS to the flask and stir to hydrolyze for 12 h. Add 0.32 g of TBOT to 1.3 g of IPA, dissolve to form a clear solution, and then add it dropwise to the flask. Adjust the water bath temperature to 50°C and continue stirring for 3 h.

[0116] (3) The water bath was heated to 70°C and the alcohol was removed for 1 hour. The resulting solution was diluted to 30 mL and then crystallized in a 50 mL hydrothermal reactor at 170°C for 72 hours. The resulting solid was collected, centrifuged, washed, and dried to obtain the catalyst precursor. The washing process was performed by washing twice with water and once with ethanol. Drying was performed in a forced air drying oven at 120°C for 12 hours.

[0117] (4) The dried catalyst was collected and ground, and then calcined in a tube furnace at 550°C for 6 h to obtain the final catalyst. The heating rate of the tube furnace was 10°C / min.

[0118] Using the above-mentioned performance evaluation steps of the present invention, when the catalyst prepared in Example 7 was applied to the series reaction of ethylene oxidation with hydrogen peroxide to prepare ethylene glycol, the ethylene glycol production rate is shown in Table 1 below.

[0119] Comparative Example 1

[0120] 11.4 g of a 2 mol in 500 mL H₂O TPAOH solution was weighed and placed in a round-bottom flask. The waterbath temperature was maintained at 30°C, and stirring was initiated at 600 rpm. 200 μL of KH590 and 1.8 mL of a 12.5 mg / mL Au solution were added, with stirring continued for 30 minutes. 7.5 g of TEOS was added to the flask and allowed to hydrolyze for 12 hours. The waterbath temperature was adjusted to 50°C, and crystallization was continued at 170°C for 72 hours with continuous stirring. The resulting solid was collected, centrifuged, washed, and dried to obtain the catalyst precursor. The precursor catalyst was calcined at 550°C for 6 hours to obtain the final catalyst, Au@S-1.

[0121] When the catalyst prepared in Comparative Example 1 was applied to the series reaction of ethylene oxide with hydrogen peroxide to prepare ethylene glycol using the above-mentioned performance evaluation steps of the present invention, the ethylene glycol production rate was shown in Table 1 below.

[0122] Comparative Example 2

[0123] Weigh the required mass of catalyst carrier TS-1 powder and place it in water. Ultrasound is used to ensure that the catalyst carrier is highly dispersed in the water. Design the metal loading required for the catalyst according to actual needs, add the corresponding amount of metal salt solution, and preferably the metal salt is tetrachloroauric acid trihydrate. Stir the impregnation solution containing the carrier configured in the step at room temperature for 3 hours, and then continue stirring at 60°C until the water is evaporated to form a dry catalyst precursor. Dry the catalyst evaporated in the step at 120°C in a forced air drying oven for 12 hours, and then roast it at 550°C in air for 6 hours to obtain the target catalyst, and the roasting heating rate is 5°C / min.

[0124] When the catalyst prepared in Comparative Example 2 was applied to the series reaction of ethylene oxide with hydrogen peroxide to prepare ethylene glycol using the above-mentioned performance evaluation steps of the present invention, the ethylene glycol production rate was shown in Table 1 below.

[0125] Comparative Example 3

[0126] Repeat Example 4, except that:

[0127] In step 3), the temperature of the hydrothermal reaction is 130° C. and the time is 48 h.

[0128] When the catalyst prepared in Comparative Example 2 was applied to the series reaction of ethylene oxide with hydrogen peroxide to prepare ethylene glycol using the above-mentioned performance evaluation steps of the present invention, the ethylene glycol production rate was shown in Table 1 below.

[0129] It can be seen that the temperature and time of the hydrothermal reaction have a great influence on the performance of the generated catalyst.

[0130] Comparative Example 4

[0131] Repeat Example 4, except that:

[0132] In step 4), the high-temperature calcination is carried out in an air atmosphere at a temperature of 400° C. and a time of 3 hours.

[0133] When the catalyst prepared in Comparative Example 4 was applied to the series reaction of ethylene oxide with hydrogen peroxide to prepare ethylene glycol using the above-mentioned performance evaluation steps of the present invention, the ethylene glycol production rate was shown in Table 1 below.

[0134] It can be seen that the temperature and time of high-temperature calcination have a great influence on the performance of the generated catalyst.

[0135] The catalyst performance evaluations of Examples 1 to 7 and Comparative Examples 1 to 4 of the present invention are shown in Table 1 below.

[0136] Table 1

[0137]

[0138]

[0139] In summary, the preparation method of the present invention, including the selection of raw materials and the selection of various parameters, constitutes an overall technical solution. Only by cooperating with each other can the encapsulated molecular sieve metal catalyst required by the present invention be obtained, thereby achieving the corresponding catalytic performance. Exceeding any condition will result in the purpose of the present invention being unable to achieve.

[0140] Obviously, the above embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention and are not intended to limit the embodiments of the present invention. Those skilled in the art will appreciate that other variations or modifications based on the above description are possible. It is not possible to enumerate all embodiments here. Any obvious variations or modifications arising from the technical solution of the present invention remain within the scope of protection of the present invention.

Claims

1. An encapsulated molecular sieve metal catalyst, characterized in that: include: Molecular sieve support and active metal component; The active metal components are evenly distributed in the pores or cage structure of the molecular sieve carrier. The active metal component is one of Pd and Au or a combination of the two; The molecular sieve carrier is titanium silicalite molecular sieve TS-1.

2. The encapsulated molecular sieve metal catalyst according to claim 1, characterized in that: The weight proportion of the active metal component in the catalyst is 0.5-5.0 wt.%.

3. The encapsulated molecular sieve metal catalyst according to claim 1, characterized in that: The active metal component further includes one or more of Fe, Co, Ni, and Sn.

4. The encapsulated molecular sieve metal catalyst according to claim 1, characterized in that: The active metal component is a metal cluster or a metal nanoparticle; the size of the active metal component particles is 0.5 to 3 nm.

5. The method for preparing the encapsulated molecular sieve metal catalyst according to any one of claims 1 to 4, characterized in that: The steps include: S1, forming a uniform and clear complex metal salt aqueous solution from an active metal precursor solution under the action of an organic ligand; S2, mixing the complex metal salt aqueous solution with the mother liquor of the synthetic molecular sieve, and performing a hydrothermal reaction to obtain an intermediate product containing the molecular sieve; S3. Collect the intermediate product by centrifugation or filtration, dry it, and perform high-temperature treatment to remove the residual template and organic ligand in the molecular sieve to obtain the molecular sieve-encapsulated metal catalyst.

6. The preparation method according to claim 5, characterized in that: In step S1, the active metal precursor solution is one or both of nitrate and chloride of active metal; the active metal is one or both of Pd and Au; Preferably, in step S1, the active metal further comprises one or more of Fe, Co, Ni, and Sn; Preferably, in step S1, the organic ligand is one or more of ammonia water, ethylenediamine, KH560, KH579, and KH590 (γ-mercaptopropyltrimethoxysilane).

7. The preparation method according to claim 5, characterized in that: In step S2, the temperature of the hydrothermal reaction is 170-200° C., and the time is 6-96 hours.

8. The preparation method according to claim 5, characterized in that: In step S3, the high temperature treatment is one of high temperature calcination and high temperature hydrogen reduction treatment.

9. The preparation method according to claim 8, characterized in that: The high temperature calcination is carried out in an air atmosphere at a temperature of 300-800° C. and a time of 1-10 hours; Preferably, the high-temperature hydrogen reduction treatment refers to a reduction temperature of 200-600° C. and a time of 1-6 h in a H 2 / N 2 atmosphere.

10. Use of the encapsulated molecular sieve metal catalyst according to any one of claims 1 to 4 as a catalyst for coupling in-situ synthesis of hydrogen peroxide and selective oxidation of hydrocarbons as a series reaction.

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