Oxidic molecular sieves, processes for their preparation and use

Abstract

The present disclosure relates to an oxidation molecular sieve, a preparation method and application thereof, which comprises the following steps: S1, mixing a silicon source, a heteroatom source, an organic template agent and optional water to obtain a first mixed material; S2, mixing the first mixed material with graphene to obtain a second mixed material, wherein the graphene is prepared by a supercritical carbon dioxide stripping method; S3, moving the second mixed material into a heat-resistant sealed container, and performing a hydrothermal reaction at 110-200 DEG C for 1-80 hours, and collecting a solid product to obtain the oxidation molecular sieve. The oxidation molecular sieve has a high activity retention rate even after high-temperature calcination, and the activity stability is significantly improved.

Description

Technical Field

[0001] This disclosure relates to an oxidized molecular sieve, its preparation method, and its application. Background Technology

[0002] Oxidized molecular sieves, such as titanium-silicon molecular sieves, can utilize low-concentration, pollution-free hydrogen peroxide as an oxidant in the oxidation of organic compounds. They can catalyze various types of organic oxidation reactions, such as the epoxidation of olefins, partial oxidation of alkanes, oxidation of alcohols, and hydroxylation of phenols. This avoids the complex processes and environmental pollution associated with traditional oxidation systems, offering unparalleled advantages in energy saving, economy, and environmental friendliness, along with excellent reaction selectivity, thus demonstrating great promise for industrial applications. However, current methods for synthesizing oxidized molecular sieves are not ideal in terms of reproducibility and stability, especially during calcination, where temperature runaway can easily occur, leading to a decline in product performance. Therefore, improving the stability of oxidized molecular sieves during calcination is a key breakthrough in their preparation, and refining the corresponding synthesis methods is crucial for their development. Summary of the Invention

[0003] The purpose of this disclosure is to provide an oxidized molecular sieve, its preparation method, and its application. This oxidized molecular sieve has good calcination stability and catalytic activity, and can effectively resist the impact of temperature runaway during the calcination process of existing molecular sieves, which leads to a decline in product performance.

[0004] To achieve the above objectives, in a first aspect, this disclosure provides a method for preparing oxidized molecular sieves, the method comprising:

[0005] S1. The silicon source, heteroatom source, organic template agent and optional water are mixed in a first mixture to obtain a first mixture.

[0006] S2. The first mixture is mixed with graphene to obtain a second mixture; wherein the graphene is prepared by supercritical carbon dioxide exfoliation.

[0007] S3. Transfer the second mixture into a heat-resistant sealed container and carry out a hydrothermal reaction at 110-200°C for 1-80 hours. Collect the solid product to obtain the oxidized molecular sieve.

[0008] Optionally, in step S1, the conditions for the first mixing include: a temperature of 60–100°C and a time of 1–24 hours.

[0009] Optionally, in step S1, the molar ratio of the silicon source, the heteroatom source, the organic template agent, and the water is 100:(0.1-5):(5-50):(800-10000), where the silicon source is SiO2 and the organic template agent is N.

[0010] Optionally, in step S1, the silicon source is one or more selected from methyl silicate, ethyl silicate, propyl silicate, butyl silicate, methylsilane, ethylsilane and propylsilane;

[0011] The heteroatom source is one or more compounds selected from those containing titanium, iron, vanadium and tin;

[0012] The organic template agent is selected from one or more of urea, quaternary ammonium bases, fatty amines, and alcoholic amines.

[0013] Optionally, in step S2, the graphene has a particle size of 0.5 to 10 micrometers.

[0014] Optionally, in step S2, the weight ratio of the first mixture to the graphene is 10000:(1~100).

[0015] Optionally, in step S2, the conditions for the second mixing include: a temperature of 20–60°C and a time of 0.1–6 hours.

[0016] Optionally, step S3 further includes: collecting the solid product and calcining it at 300-900°C for 1-12 hours to obtain the oxidized molecular sieve.

[0017] A second aspect of this disclosure provides an oxidized molecular sieve prepared using the method described in the first aspect of this disclosure.

[0018] A third aspect of this disclosure provides the application of the oxidized molecular sieve described in the second aspect of this disclosure in the catalytic oxidation reaction of phenol.

[0019] Through the above technical solution, this disclosure incorporates graphene prepared using supercritical carbon dioxide exfoliation during the preparation of oxidized molecular sieves. This allows for the effective utilization of the reactive centers of the oxidized molecular sieves and maintains a high activity retention rate after high-temperature calcination, effectively improving the reactivity, selectivity of the target product, and activity stability of the oxidized molecular sieves. The method disclosed herein effectively combats the significant decrease in activity caused by temperature runaway during the calcination process of oxidized molecular sieves, improving the stability of the oxidized molecular sieves during calcination and thus increasing the yield of oxidized molecular sieves. It is particularly suitable for the industrial calcination process of oxidized molecular sieves.

[0020] Other features and advantages of this disclosure will be described in detail in the following detailed description section. Detailed Implementation

[0021] The following provides a detailed description of specific embodiments of this disclosure. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit this disclosure.

[0022] In a first aspect, this disclosure provides a method for preparing oxidized molecular sieves, the method comprising:

[0023] S1. The silicon source, heteroatom source, organic template agent and optional water are mixed in a first mixture to obtain a first mixture.

[0024] S2. The first mixture is mixed with graphene to obtain a second mixture; wherein the graphene is prepared by supercritical carbon dioxide exfoliation.

[0025] S3. Transfer the second mixture into a heat-resistant sealed container and carry out a hydrothermal reaction at 110-200°C for 1-80 hours. Collect the solid product to obtain the oxidized molecular sieve.

[0026] This disclosure discloses graphene prepared using a special supercritical carbon dioxide exfoliation method. Compared to graphene prepared by other methods, this graphene exhibits a more uniform particle size distribution and can generate appropriately ordered mesopores and / or macropores during the synthesis of oxidative molecular sieves. This enhances its high-temperature tolerance during calcination and effectively resists the impact of runaway temperatures during industrial calcination on its activity. Simultaneously, the presence of these appropriately ordered mesopores and / or macropores can, on the one hand, appropriately increase the accessibility of the reactive centers of the oxidative molecular sieve, and on the other hand, further enhance the diffusion rate of materials in the catalytic reaction of the oxidative molecular sieve, thereby improving the reactivity, activity stability, and selectivity of the oxidative molecular sieve for target products.

[0027] According to this disclosure, in step S1, the conditions for the first mixing may include: a temperature of 60–100°C and a time of 1–24 hours. Preferably, the conditions for the first mixing include: a temperature of 75–95°C and a time of 2–12 hours. This disclosure does not impose specific limitations on the method of first mixing of the raw materials, as long as the raw materials can be mixed evenly. For example, the first mixing can be carried out under stirring conditions, and the stirring speed can be 50–1000 rpm. In a preferred embodiment of this disclosure, in order to further improve the dispersion of the materials, the method further includes: in step S1, the silicon source and the heteroatom source are premixed first, and then the organic template agent is added to carry out the first mixing.

[0028] The amounts of the silicon source, heteroatom source, and organic template agent can be adjusted within a wide range. Specifically, in the first mixture, the molar ratio of the silicon source, heteroatom source, organic template agent, and water can be 100:(0.1-5):(5-50):(800-10000), preferably 100:(0.2-4):(10-40):(1000-6000). The silicon source is calculated as SiO2, and the organic template agent is calculated as N.

[0029] The silicon source can be a common type in the art. For example, the silicon source can be selected from organosilicon sources and / or inorganic silicon sources. The organosilicon source can include, but is not limited to, one or more of methyl silicate, ethyl silicate, propyl silicate and butyl silicate. The inorganic silicon source can include, but is not limited to, one or more of methylsilane, ethylsilane and propylsilane.

[0030] The heteroatom source can be one or more of titanium, iron, vanadium, and tin sources. Specifically, the heteroatom source can be one or more of compounds containing titanium, iron, vanadium, and tin. Among them, the titanium-containing compounds can be, for example, titanate esters, titanium tetrachloride, titanium oxysulfate, etc., preferably one or more of tetrabutyl titanate, tetraisopropyl titanate, and titanium oxysulfate; the iron-containing compounds can be, for example, ferric nitrate, ferric hydroxide, ferric oxide, ferric chloride, ferric sulfate, ferric acetylacetone, ferric isopropoxide, ferric phosphate, ferric acetate, ferric acid and its salts, preferably one or more of ferric hydroxide, ferric oxide, ferric chloride, ferric sulfate, and ferric acid; the vanadium-containing compounds can be, for example, vanadic acid, ammonium vanadate, sodium vanadate, vanadium oxide, etc., preferably one or more of ammonium vanadate, sodium vanadate, and vanadium oxide; the tin-containing compounds can be, for example, ammonium stannate, tin tetrachloride, tin sulfate, tin oxide, etc., preferably one or more of tin tetrachloride and tin oxide.

[0031] The organic template agent can be of common types in the art. For example, the organic template agent can be selected from urea, quaternary ammonium bases, aliphatic amines, or alkanolamines, or one or more of them. Specifically, the quaternary ammonium base can be tetraethylammonium hydroxide, tetrapropylammonium hydroxide, or tetrabutylammonium hydroxide, or a combination of two or three of them; the aliphatic amine can be ethylamine, n-butylamine, butanediamine, or hexamethylenediamine, or a combination of two or three of them; and the alkanolamine can be selected from monoethanolamine, diethanolamine, or triethanolamine, or a combination of two or three of them.

[0032] According to this disclosure, in step S2, the graphene can be any existing graphene prepared using the supercritical carbon dioxide exfoliation method. The inventors of this disclosure unexpectedly discovered during their research that by adding graphene prepared using the supercritical carbon dioxide exfoliation method, the prepared oxide molecular sieve can resist the influence of runaway temperatures during calcination on its performance, thus giving the oxide molecular sieve better calcination stability. This disclosure does not impose any special limitations on the specific preparation method of the graphene using supercritical carbon dioxide exfoliation; for example, it can be the method disclosed in Chinese patent applications CN106517168A and CN106430167A.

[0033] Furthermore, the graphene particle size can be 0.5–10 micrometers, preferably 1–5 micrometers. Here, the particle size refers to the D50 particle size. Graphene within the above particle size range is beneficial for further improving the calcination stability and reactivity of the oxidized molecular sieve.

[0034] The amount of graphene can be adjusted within a wide range. Specifically, the weight ratio of the first mixture to the graphene can be 10000:(1-100), preferably 10000:(5-50).

[0035] The second mixing conditions may include a temperature of 20–60°C and a time of 0.1–6 hours. Preferably, the second mixing conditions include a temperature of 30–50°C and a time of 0.5–3 hours. The method of mixing the first mixture with the graphene is not specifically limited, as long as it enables the two to be mixed. For example, the two can be placed in a beaker and stirred to mix them, with the stirring speed being 200–5000 rpm.

[0036] According to this disclosure, in step S3, the preferred conditions for the hydrothermal reaction are: a temperature of 120–180°C and a time of 6–72 hours. The hydrothermal reaction is well known to those skilled in the art and can be carried out in a heat- and pressure-resistant closed container, such as a high-pressure reactor. This disclosure does not specifically limit the pressure of the hydrothermal reaction; it can be carried out under autogenous pressure or under applied pressure, preferably under autogenous pressure.

[0037] In one specific embodiment of this disclosure, step S3 further includes: collecting the solid product and calcining it at 300–900°C for 1–12 hours to obtain the oxidized molecular sieve. Compared with oxidized molecular sieves prepared by existing methods, the calcined oxidized molecular sieve obtained by the method of this disclosure has a higher activity retention rate. Preferably, the calcination conditions are: temperature of 500–800°C and time of 2–8 hours. The calcination is well known to those skilled in the art, and can be carried out in, for example, in a muffle furnace or a tube furnace. This disclosure does not specifically limit the calcination atmosphere, for example, it can be an air atmosphere or an inert atmosphere. The method of this disclosure has a wide range of calcination temperature requirements, which is beneficial for industrial production.

[0038] This disclosure does not limit the method for collecting solid products; any method that can separate solids from liquids is acceptable, such as including but not limited to filtration and centrifugation.

[0039] A second aspect of this disclosure provides an oxidized molecular sieve prepared using the method described in the first aspect of this disclosure.

[0040] According to this disclosure, oxidized molecular sieves are well known to those skilled in the art and can be used as catalytic materials in oxidation reactions. The oxidized molecular sieves described in this disclosure may include, but are not limited to, titanium-containing molecular sieves, iron-containing molecular sieves, vanadium-containing molecular sieves, and tin-containing molecular sieves.

[0041] A third aspect of this disclosure provides the application of the oxidized molecular sieve described in the second aspect of this disclosure in the catalytic oxidation reaction of phenol.

[0042] In one specific embodiment of this disclosure, the catalytic oxidation reaction of phenol is carried out using a method comprising the following steps: An oxidizing molecular sieve, a solvent, phenol, and an oxidant are added to a reactor (such as a high-pressure reactor) in a weight ratio of oxidizing molecular sieve: solvent: phenol: oxidant = 1:(5-100):(10-50):(1-20). The reaction temperature is controlled at 40-100°C and the reaction pressure at 0.1-2 MPa, and the reaction is carried out for 1-6 hours. Preferably, the oxidant is an aqueous solution of hydrogen peroxide, with an H2O2 content of 1-50% by weight. Water is a preferred solvent, as it is environmentally friendly.

[0043] The present disclosure will be further illustrated by the following examples, but the present disclosure is not limited thereto.

[0044] All reagents used in the examples and comparative examples were commercially available analytical grade reagents.

[0045] The graphene used in the examples was prepared by supercritical rapid decompression according to the preparation methods of Examples 2, 3, 5 and 6 in Chinese patent application CN106517168A, and was respectively designated as CUP1 (D50 particle size of 2.8 μm), CUP2 (D50 particle size of 0.5 μm), CUP3 (D50 particle size of 10 μm) and CUP4 (D50 particle size of 12.5 μm).

[0046] Example 1

[0047] S1. Ethyl silicate and tetrabutyl titanate are premixed at 80°C for 1 hour, and then mixed with tetrapropylammonium hydroxide at 85°C with a stirring speed of 300 rpm for 8 hours to obtain a first mixture; wherein the molar ratio of silicate (calculated as SiO2), titanate (calculated as TiO2), tetrapropylammonium hydroxide (calculated as N) and water is 100:3:20:2500;

[0048] S2. The first mixture and graphene CUP1 are mixed at a weight ratio of 10000:20 at 30°C and a stirring speed of 800 rpm for 1 hour to obtain the second mixture.

[0049] S3. The second mixture is transferred to a sealed high-pressure reactor and hydrothermally treated at 150°C and autogenous pressure for 48 hours. The resulting material is filtered, washed with water, naturally dried, and then calcined at 550°C for 3 hours to obtain oxidized molecular sieve A1.

[0050] Comparative Example 1

[0051] Oxidized molecular sieve DB1 was prepared according to the method of Example 1, except that step S2 was omitted, i.e., graphene was not introduced for a second mixing and the process was directly hydrothermal.

[0052] Example 2

[0053] Oxidized molecular sieve A2 was prepared using the same method as in Example 1, except that in step S3, it was calcined at 800°C for 3 hours.

[0054] Comparative Example 2

[0055] The oxidized molecular sieve DB2 was prepared according to the method of Example 2, except that step S2 was omitted, i.e., graphene was not introduced for the second mixing and the process was carried out directly by hydrothermal treatment.

[0056] Example 3

[0057] S1. Ethyl silicate and tetrabutyl titanate are premixed at 70°C for 0.5 hours, and then mixed with tetrapropylammonium hydroxide at 75°C and a stirring speed of 100 rpm for 2 hours to obtain a first mixture; wherein the molar ratio of silicate (calculated as SiO2), titanate, tetrapropylammonium hydroxide (calculated as N) and water is 100:3:20:5000;

[0058] S2. The first mixture and graphene CUP1 are mixed at a weight ratio of 10000:10 at 30°C and a stirring speed of 1500 rpm for 2 hours to obtain the second mixture.

[0059] S3. The second mixture is transferred to a sealed high-pressure reactor and hydrothermally treated at 170°C and autogenous pressure for 48 hours. The resulting material is filtered, washed with water, naturally dried, and then calcined at 500°C for 3 hours to obtain oxidized molecular sieve A3.

[0060] Comparative Example 3

[0061] Oxidized molecular sieve DB3 was prepared according to the method of Example 3, except that step S2 was omitted, i.e., graphene was not introduced for the second mixing and the process was carried out directly by hydrothermal treatment.

[0062] Example 4

[0063] Oxidized molecular sieve A4 was prepared using the same method as in Example 3, except that in step S3, it was calcined at 700°C for 3 hours.

[0064] Comparative Example 4

[0065] The oxidized molecular sieve DB4 was prepared according to the method of Example 4, except that step S2 was omitted, i.e., graphene was not introduced for the second mixing and the process was carried out directly by hydrothermal treatment.

[0066] Example 5

[0067] Oxidized molecular sieve A5 was prepared using the same method as in Example 3, except that in step S3, it was calcined at 900°C for 10 hours.

[0068] Comparative Example 5

[0069] The oxidized molecular sieve DB5 was prepared according to the method of Example 5, except that step S2 was omitted, i.e., graphene was not introduced for the second mixing and the process was directly hydrothermal.

[0070] Example 6

[0071] Oxidized molecular sieve A6 was prepared using the same method as in Example 2, except that in step S2, the weight ratio of the first mixture to graphene CUP1 was 10000:1.

[0072] Comparative Example 6

[0073] The oxidized molecular sieve DB6 was prepared according to the method of Example 6, except that step S2 was omitted, i.e., graphene was not introduced for the second mixing and the process was carried out directly by hydrothermal treatment.

[0074] Example 7

[0075] Oxidized molecular sieve A7 was prepared using the same method as in Example 2, except that in step S2, the weight ratio of the first mixture to graphene CUP1 was 10000:100.

[0076] Comparative Example 7

[0077] The oxidized molecular sieve DB7 was prepared according to the method of Example 7, except that step S2 was omitted, i.e., graphene was not introduced for the second mixing and the process was carried out directly by hydrothermal treatment.

[0078] Example 8

[0079] Oxidized molecular sieve A8 was prepared using the same method as in Example 2, except that in step S2, the same amount of graphene CUP2 was used instead of CUP1.

[0080] Comparative Example 8

[0081] The oxidized molecular sieve DB8 was prepared according to the method of Example 8, except that step S2 was omitted, i.e., graphene was not introduced for the second mixing and the process was carried out directly by hydrothermal treatment.

[0082] Example 9

[0083] Oxidized molecular sieve A9 was prepared using the same method as in Example 2, except that in step S2, the same amount of graphene CUP3 was used instead of CUP1.

[0084] Comparative Example 9

[0085] The oxidized molecular sieve DB9 was prepared according to the method of Example 9, except that step S2 was omitted, i.e., graphene was not introduced for the second mixing and the process was carried out directly by hydrothermal treatment.

[0086] Example 10

[0087] Oxidized molecular sieve A10 was prepared using the same method as in Example 2, except that in step S2, the same amount of graphene CUP4 was used instead of CUP1.

[0088] Comparative Example 10

[0089] Oxidized molecular sieve DB10 was prepared according to the method of Example 10, except that step S2 was omitted, i.e., graphene was not introduced for a second mixing and the process was directly hydrothermal.

[0090] Example 11

[0091] Oxidized molecular sieve Al11 was prepared using the same method as in Example 2, except that in step S1, the molar ratio of silicate ester (calculated as SiO2), titanate ester, tetrapropylammonium hydroxide (calculated as N) and water in the first mixture was 100:0.15:5:800, and the first mixing conditions were: temperature 60°C, stirring speed 1000 rpm, and time 1 hour; in step S2, the second mixing conditions were: temperature 60°C, stirring speed 100 rpm, and time 0.1 hours; and in step S3, the hydrothermal reaction mixing conditions were: temperature 110°C, and time 5 hours.

[0092] Comparative Example 11

[0093] Oxidized molecular sieve DB11 was prepared according to the method of Example 11, except that step S2 was omitted, i.e., graphene was not introduced for the second mixing and the process was directly hydrothermal.

[0094] Example 12

[0095] Oxidized molecular sieve A12 was prepared using the same method as in Example 2, except that in step S1, ethyl silicate and ferric nitrate were premixed at 80°C for 4 hours, and then mixed with tetraethylammonium hydroxide at 85°C with a stirring speed of 500 rpm for 8 hours to obtain a first mixture; wherein the molar ratio of ethyl silicate (calculated as SiO2), ferric nitrate, tetraethylammonium hydroxide (calculated as N) and water was 100:1:40:1000.

[0096] Comparative Example 12

[0097] The oxidized molecular sieve DB12 was prepared according to the method of Example 12, except that step S2 was omitted, i.e., graphene was not introduced for the second mixing and the process was carried out directly by hydrothermal treatment.

[0098] Comparative Example 13

[0099] Oxidized molecular sieve DB13 was prepared according to the method in Example 2, except that in step S2, the same amount of graphene obtained by redox method (purchased from Changzhou Sixth Element Materials Technology Co., Ltd., trade number SE1233, D50 particle size of 9 micrometers) was introduced.

[0100] Comparative Example 14

[0101] The oxidized molecular sieve DB14 was prepared according to the method in Example 2, except that in step S2, the same amount of graphene obtained by the redox method (purchased from Dichuang (Suzhou) New Material Technology Co., Ltd., trade number DCRGO-200, D50 particle size of 10 micrometers) was introduced.

[0102] Comparative Example 15

[0103] The oxidized molecular sieve DB15 was prepared according to the method of Example 2, except that in step S2, the same amount of solid-phase intercalation exfoliated graphene (purchased from Deyang Xitan Technology Co., Ltd., trade number HE-01, D50 particle size of 12 micrometers) was introduced.

[0104] Comparative Example 16

[0105] The oxidized molecular sieve DB16 was prepared according to the method of Example 2, except that in step S2, the same amount of carbon nanotubes (purchased from Shandong Dazhan Nanomaterials Co., Ltd., trade number GT-300, tube diameter 10-15 nm, tube length 3-12 μm) were introduced.

[0106] Test Example 1

[0107] The oxidized molecular sieves prepared in the examples and comparative examples were used as catalysts for the catalytic oxidation of phenol.

[0108] The catalyst, solvent water, phenol, and hydrogen peroxide aqueous solution (the H2O2 content in the hydrogen peroxide aqueous solution is 30% by weight) were sealed in a high-pressure reactor at a weight ratio of catalyst:water:phenol:hydrogen peroxide aqueous solution = 1:20:20:5. The reaction temperature was controlled at 60°C and the reaction was carried out at this temperature for 2 hours.

[0109] The product distribution of the reaction products was determined using an Agilent 6890 gas chromatograph with an HP-1 capillary column (30m × 0.25mm). The test results are shown in Table 1.

[0110] The following formulas are used to calculate the feed conversion rate and target product selectivity:

[0111] Phenol conversion rate = (molar amount of phenol added before reaction - molar amount of phenol remaining after reaction) / molar amount of phenol added before reaction × 100%;

[0112] Selectivity of the target product hydroquinone = (molar amount of catechol generated after the reaction + molar amount of hydroquinone generated after the reaction) / (molar amount of phenol added before the reaction - molar amount of phenol remaining after the reaction) × 100%;

[0113] The activity retention rate was calculated based on the phenol conversion rate of the corresponding comparative example without graphene (i.e., the activity retention rate of the corresponding comparative example was 100%).

[0114] Table 1

[0115]

[0116]

[0117] As shown in Table 1, compared with methods that do not introduce graphene or introduce non-supercritical carbon dioxide to exfoliate graphene during the preparation process, the oxidized molecular sieve prepared by the method disclosed in this paper exhibits higher phenol conversion rate, target product selectivity, and higher catalytic activity retention when used for the catalytic oxidation reaction of phenol. In particular, the catalytic activity of the oxidized molecular sieve prepared by the method disclosed in this paper does not decrease significantly after high-temperature calcination, demonstrating excellent calcination stability. This indicates that the molecular sieve obtained by the method disclosed in this paper can effectively resist the drawback of significant activity reduction caused by temperature runaway during calcination.

[0118] The preferred embodiments of this disclosure have been described in detail above. However, this disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this disclosure, various simple modifications can be made to the technical solutions of this disclosure, and these simple modifications all fall within the protection scope of this disclosure.

[0119] 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, this disclosure will not describe the various possible combinations separately.

[0120] Furthermore, various different embodiments of this disclosure can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content disclosed in this disclosure.

Claims

1. A method for preparing oxidized molecular sieves, characterized in that, The method includes: S1. The silicon source, heteroatom source, organic template agent and optional water are mixed in a first mixture to obtain a first mixture. S2. The first mixture is mixed with graphene to obtain a second mixture; wherein the graphene is prepared by supercritical carbon dioxide exfoliation. S3. Transfer the second mixture into a heat-resistant sealed container and carry out a hydrothermal reaction at 110-200°C for 1-80 hours. Collect the solid product to obtain the oxidized molecular sieve.

2. The method according to claim 1, wherein, In step S1, the conditions for the first mixing include: a temperature of 60 to 100°C and a time of 1 to 24 hours.

3. The method according to claim 1, wherein, In step S1, the molar ratio of the silicon source, the heteroatom source, the organic template agent, and the water is 100:(0.1-5):(5-50):(800-10000), the silicon source is SiO2, and the organic template agent is N.

4. The method according to claim 1, wherein, In step S1, the silicon source is one or more selected from methyl silicate, ethyl silicate, propyl silicate, butyl silicate, methylsilane, ethylsilane and propylsilane; The heteroatom source is one or more compounds selected from those containing titanium, iron, vanadium and tin; The organic template agent is selected from one or more of urea, quaternary ammonium bases, fatty amines, and alcoholic amines.

5. The method according to claim 1, wherein, In step S2, the graphene has a particle size of 0.5 to 10 micrometers.

6. The method according to claim 1, wherein, In step S2, the weight ratio of the first mixture to the graphene is 10000:(1~100).

7. The method according to claim 1, wherein, In step S2, the conditions for the second mixing include: a temperature of 20 to 60°C and a time of 0.1 to 6 hours.

8. The method according to claim 1, wherein, Step S3 further includes: collecting the solid product and calcining it at 300-900°C for 1-12 hours to obtain the oxidized molecular sieve.

9. The oxidized molecular sieve prepared by the method according to any one of claims 1 to 8.

10. The application of the oxidized molecular sieve according to claim 9 in the catalytic oxidation reaction of phenol.

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