A modified oxidation catalytic material, its preparation method and application

Abstract

The present invention relates to a modified oxidation catalytic material, a preparation method thereof and an application. The method includes: S1. Connect a graphite compact and a conductive object to the positive electrode and the negative electrode of a DC power supply respectively, and place them in an aqueous solution of an inorganic base. Electrolyze for 1 - 10 days at a voltage of 10 - 40 V to obtain an alkaline carbon dot solution; S2. Perform a first mixing of a silicon source and the alkaline carbon dot solution to obtain a mixed solution; S3. After performing a second mixing of the mixed solution and the oxidation catalytic material, transfer the obtained mixture into a heat-resistant sealed container, and carry out a hydrothermal reaction at 110 - 200 °C for 6 - 72 hours, and collect the solid product to obtain the modified oxidation catalytic material. The method of the present invention can prepare a modified oxidation catalytic material with relatively excellent catalytic activity. For example, when it is used in the catalytic oxidation reaction of olefins with 8 - 12 carbon atoms, the performance is excellent.

Description

Technical Field

[0001] The present invention relates to a modified oxidation catalytic material, a preparation method thereof and an application thereof. Background Art

[0002] In the oxidation reaction of organic substances, oxidation catalytic materials such as titanium silicalite can use low-concentration hydrogen peroxide without pollution as an oxidant, and can catalyze various types of organic oxidation reactions, such as epoxidation of olefins, partial oxidation of alkanes, oxidation of alcohols, hydroxylation of phenols, etc., avoiding the problems of complex process and environmental pollution in the oxidation process, having advantages of energy saving, economy and environmental friendliness that are unparalleled by traditional oxidation systems, and having good reaction selectivity. Therefore, it has great industrial application prospects. However, at present, the repeatability, stability and cost of the synthesis method of oxidation catalytic materials are not very ideal. Therefore, improving the corresponding synthesis method is the key to the development of oxidation catalytic materials. Small carbon nanoparticles with a size less than 10 nm found for the first time when purifying single-walled carbon nanotubes by electrophoresis were named carbon quantum dots (abbreviated as carbon dots) for the first time. It is a new type of small-size carbon nanomaterial. Due to its excellent fluorescence properties, carbon quantum dots are also called fluorescent carbon quantum dots. In just a few years from the discovery to the utilization of carbon quantum dots, carbon quantum dots have become a new star in the carbon nanomaterial family. In recent years, the properties and utilization of carbon quantum dots in various aspects have been studied more and more carefully and comprehensively, and significant progress has finally been made. Therefore, the research on the properties and utilization of carbon quantum dots has received more and more attention from people. Utilizing its properties to modify oxidation catalytic materials in combination with the characteristics of carbon quantum dots is a modification route of oxidation catalytic materials worthy of exploration. Summary of the Invention

[0003] The object of the present invention is to provide a modified oxidation catalytic material, a preparation method thereof and an application thereof. The reaction active centers of the modified oxidation catalytic material prepared by the method of the present invention can be effectively utilized, and it has better macromolecular reaction activity and target product selectivity.

[0004] To achieve the above object, in the first aspect of the present invention, a method for preparing a modified oxidation catalytic material is provided, and the method includes:

[0005] S1. Connect a graphite compact and a conductor to the positive electrode and the negative electrode of a DC power supply respectively, and place them in an aqueous solution of an inorganic base, and electrolyze for 1-10 days at a voltage of 10-40 V to obtain an alkaline carbon dot solution;

[0006] S2. Perform a first mixing of a silicon source and the alkaline carbon dot solution to obtain a mixed solution;

[0007] S3. After the second mixing of the mixture with the oxidation catalytic material, transfer the obtained mixture into a heat-resistant sealed container, carry out a hydrothermal reaction at 110 - 200 °C for 6 - 72 hours, and collect the solid product to obtain the modified oxidation catalytic material.

[0008] Optionally, in step S1, the content of the inorganic base in the aqueous solution of the inorganic base is 0.1 - 25% by weight.

[0009] Optionally, in step S1, the carbon dot concentration of the alkaline carbon dot solution is 0.01 - 2 mg / L; the weight ratio of the content of the base to the carbon dots in the alkaline carbon dot solution is (10 - 500):1.

[0010] Optionally, in step S2, the conditions for the first mixing include: the temperature is 20 - 100 °C, and the time is 1 - 24 hours;

[0011] The weight ratio of the amount of the silicon source to the alkaline carbon dot solution is 1:(2 - 100); the silicon source is selected from one or more of methyl silicate, ethyl silicate, propyl silicate, butyl silicate, methyl silane, ethyl silane, and propyl silane.

[0012] Optionally, in step S3, the conditions for the second mixing include: the temperature is 20 - 60 °C, and the time is 0.1 - 6 hours; the conditions for the hydrothermal reaction include: the temperature is 120 - 200 °C, and the time is 1 - 80 hours;

[0013] The weight ratio of the amount of the mixture to the oxidation catalytic material is 100:(1 - 100).

[0014] Optionally, step S3 further includes: collecting the solid product and calcining it at 300 - 650 °C for 1 - 12 hours.

[0015] Optionally, the inorganic base is selected from one or more of ammonia, sodium hydroxide, potassium hydroxide, calcium hydroxide, and barium hydroxide;

[0016] The oxidation catalytic material is selected from one or more of titanium-containing molecular sieves, iron-containing molecular sieves, vanadium-containing molecular sieves, and tin-containing molecular sieves.

[0017] The second aspect of the present invention provides a modified oxidation catalytic material prepared by the method provided in the first aspect of the present invention.

[0018] Optionally, the mesoporous volume of the modified oxidation catalytic material accounts for 50 - 75% of the total pore volume, and the ratio of the mesoporous volume ratio to the mesoporous specific surface area ratio is 1.5 - 2.5.

[0019] The third aspect of the present invention provides an application of the modified oxidation catalytic material provided by the second aspect of the present invention in the catalytic oxidation reaction of olefins, wherein the number of carbon atoms of the olefins is 5-10.

[0020] Through the above technical solution, the method of the present invention can increase the accessibility of the reaction active centers of the oxidation catalytic material, so that the reaction active centers of the modified oxidation catalytic material can be effectively utilized, and further make the modified oxidation catalytic material have better reaction activity, selectivity of the target product, and activity stability.

[0021] Other features and advantages of the present invention will be described in detail in the following specific implementation part. Specific Embodiments

[0022] The following will describe in detail the specific embodiments of the present invention. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0023] The first aspect of the present invention provides a method for preparing a modified oxidation catalytic material, the method comprising:

[0024] S1. Connect a graphite formed body and a conductive object to the positive and negative electrodes of a DC power supply respectively, and place them in an aqueous solution of an inorganic base, and electrolyze for 1-10 days at a voltage of 10-40V to obtain an alkaline carbon dot solution;

[0025] S2. Perform a first mixing of a silicon source and the alkaline carbon dot solution to obtain a mixed solution;

[0026] S3. After performing a second mixing of the mixed solution and the oxidation catalytic material, transfer the obtained mixture into a heat-resistant sealed container, and perform a hydrothermal reaction at 110-200°C for 6-72 hours, and collect the solid product to obtain the modified oxidation catalytic material.

[0027] In the method of the present invention, in the presence of an alkaline carbon dot solution, mesopores, macropores and other defects can be generated in the oxidation catalytic material during the treatment process, and the presence of the silicon source can effectively control the treatment process so that the mesopores, macropores and other defects generated during the treatment process are more orderly. On the one hand, it can appropriately increase the accessibility of the reaction active centers of the oxidation catalytic material, and on the other hand, it can further specifically improve the diffusion rate of reactants and products, thereby facilitating the improvement of the reaction activity and activity stability of the oxidation catalytic material, as well as the selectivity of the target product.

[0028] In a specific embodiment of the present invention, in step S1, the voltage of the electrolysis is 2-35V and the time is 1-5 days to obtain an alkaline carbon dot solution.

[0029] In a specific embodiment of the present invention, in step S1, the content of the inorganic base in the aqueous solution of the inorganic base can vary within a relatively large range, for example, it can be 0.1-25% by weight, preferably 1-10% by weight.

[0030] In a specific embodiment of the present invention, in step S1, the carbon dot concentration of the alkaline carbon dot solution is 0.01-2 mg / L, preferably 0.02-1 mg / L; the weight ratio of the base to the carbon dots in the alkaline carbon dot solution is (10-500):1, preferably (20-200):1.

[0031] In a specific embodiment of the present invention, step S1 may include: concentrating the alkaline carbon dot solution. The concentration treatment is a technical means commonly used by those skilled in the art, such as membrane separation concentration, etc., which will not be elaborated herein. The carbon dot concentration of the alkaline carbon dot solution obtained after concentration treatment can be 0.05-2 mg / mL. In a preferred embodiment, the carbon dot concentration of the carbon dot solution obtained after concentration treatment is 0.1-1 mg / mL.

[0032] According to the present invention, the graphite formed body can be a graphite rod or a graphite plate, and no specific limitations are imposed on the sizes of the graphite formed body and the conductive object. Preferably, the size of the graphite formed body matches the size of the conductive object. The size of the graphite formed body can vary within a relatively large range. For example, when the graphite formed body is a graphite rod, the diameter of the graphite rod can be 2-20 mm, and the length can be 2-100 cm, where the length refers to the axial length of the graphite rod; when the graphite formed body is a graphite plate, the length of the graphite plate can be 5-100 cm, the width can be 1-100 cm, and the thickness can be 0.01-10 mm. The conductive object can be various common substances capable of conducting electricity, and there are no requirements for the material and shape. For example, the shape can be a common rod shape or plate shape, preferably a rod shape, such as an iron rod, a graphite rod, a copper rod, etc., and further preferably a graphite rod. There are no special limitations on the size of the conductive object, and most preferably it is a graphite rod that matches the size of the graphite formed body. During electrolysis, a certain distance can be maintained between the graphite formed body and the conductive object, for example, 3-10 cm.

[0033] According to the present invention, there is no specific limitation on the way of first mixing the silicon source and the alkaline carbon dot solution, as long as the two can be mixed. For example, the silicon source and the alkaline carbon dot solution can be placed in a beaker and stirred to mix them. In a specific embodiment of the present invention, in step S2, the conditions for the first mixing include: the temperature is 20 - 100 °C, and the time is 1 - 24 hours; preferably, the temperature is 25 - 80 °C, and the time is 2 - 12 hours. The weight ratio of the amount of the silicon source to the alkaline carbon dot solution can vary within a relatively large range, for example, it can be 1:(2 - 100), preferably 1:(5 - 50). The silicon source can be selected from organic silicon sources and / or inorganic silicon sources. The organic silicon 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.

[0034] In a specific embodiment of the present invention, in step S3, the conditions for the second mixing include: the temperature is 20 - 60 °C, and the time is 0.1 - 6 hours; the conditions for the hydrothermal reaction include: the temperature is 120 - 200 °C, and the time is 1 - 80 hours. The hydrothermal reaction is well-known to those skilled in the art and can be carried out in a heat-resistant and pressure-resistant closed container, such as in a high-pressure reaction kettle. The present invention does not specifically limit the pressure of the hydrothermal reaction, and it can be carried out under self-generated pressure or under external pressure, preferably under self-generated pressure (usually carried out in a closed container).

[0035] In a specific embodiment of the present invention, the weight ratio of the amount of the mixed solution to the oxidation catalytic material is 100:(1 - 100), preferably 100:(6 - 60).

[0036] In a specific embodiment of the present invention, step S3 further includes: collecting the solid product and calcining it at 300 - 650 °C for 1 - 12 hours, preferably calcining it at 400 - 600 °C for 2 - 8 hours. Calcination is well-known to those skilled in the art and can be carried out in, for example, a muffle furnace or a tube furnace. The present invention does not specifically limit the atmosphere for calcination. For example, it can be an air atmosphere or an inert atmosphere. The present invention also does not limit the method for collecting the solid, as long as it can separate the solid from the liquid, for example, it can include, but is not limited to, filtration, centrifugal separation, etc.

[0037] In a specific embodiment of the present invention, the inorganic base is selected from one or more of ammonia, sodium hydroxide, potassium hydroxide, calcium hydroxide, and barium hydroxide; the oxidation catalytic material is well-known to those skilled in the art, that is, the catalytic material applicable to oxidation reactions. The oxidation catalytic material can include, but is not limited to, one or more of titanium-containing molecular sieves, iron-containing molecular sieves, vanadium-containing molecular sieves, and tin-containing molecular sieves.

[0038] The second aspect of the present invention provides a modified oxidation catalytic material prepared by the method provided in the first aspect of the present invention.

[0039] In a specific embodiment of the present invention, the mesopore volume of the modified oxidation catalytic material accounts for 40-80% of the total pore volume, preferably 50-75%, and the ratio of the mesopore volume ratio to the mesopore specific surface area ratio is 1.0-5.0, preferably 1.5-2.5. Among them, the mesopore volume ratio refers to the ratio of the mesopore volume to the total pore volume, and the mesopore specific area ratio refers to the ratio of the mesopore specific area to the total pore specific area. The modified oxidation catalytic material of the present invention has a relatively high mesopore volume ratio, and has high activity when used in the catalytic oxidation of olefins, and can effectively improve the conversion rate of raw materials and the selectivity of target products.

[0040] The third aspect of the present invention provides an application of the modified oxidation catalytic material provided in the second aspect of the present invention in the catalytic oxidation reaction of olefins, wherein the olefin is a cycloolefin with 8-12 carbon atoms or a branched olefin with 6-12 carbon atoms.

[0041] In a specific embodiment of the present invention, the olefin is selected from one or more of cyclooctene, styrene, methylcycloheptene, methylcyclooctene, and dimethylhexene.

[0042] In a specific embodiment of the present invention, a method including the following steps is used for the oxidation reaction of olefins: adding the modified oxidation catalytic material, solvent, olefin, and oxidant into a reactor such as a high-pressure reaction kettle according to the weight ratio of modified oxidation catalytic material: solvent: olefin: oxidant = 1:(5-100):(1-50):(1-100), controlling the reaction temperature to be 40-120 °C and the reaction pressure to be 0.1-2 MPa, and reacting for 1-6 hours. Preferably, the oxidant is an aqueous hydrogen peroxide solution, and the content of H 2 O 2 is 1-50% by weight, and the solvent is a common solvent such as alcohol, ketone, acid, ester, etc., and may include but are not limited to methanol, acetone, etc.

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

[0044] The reagents used in the examples and comparative examples are all commercially available analytical pure reagents.

[0045] The oxidation catalytic material used is a titanium-containing molecular sieve synthesized according to the method disclosed in the prior art (Thangaraj A, Eapen M J, Sivasanker S, et al. Studies on the synthesis of titanium silicalite, TS-1[J]. Zeolites, 1992, 12(8): 943-950), denoted as CAT-1.

[0046] In the examples and comparative examples, the mesoporous specific surface area and the total specific surface area were measured by the nitrogen adsorption capacity method and calculated according to the BJH calculation method (see Petrochemical Analysis Methods (RIPP Test Methods), RIPP151-90, published by Science Press in 1990).

[0047] Example 1

[0048] S1. At normal temperature and pressure, 800 mL of ultrapure water and potassium hydroxide (the weight ratio of water to potassium hydroxide is 100:2.04) were added to a 1000 mL beaker as the electrolyte. An anode graphite rod (diameter 8 mm, length 50 cm) and a cathode graphite rod (diameter 8 mm, length 50 cm) were placed therein, and the distance between the anode graphite rod and the cathode graphite rod was maintained at 8 cm. The anode graphite rod was connected to the positive pole of a DC power supply and the cathode rod was connected to the negative pole of the DC power supply, and a voltage of 15 V was applied for electrolysis for 4 days. After that, concentration treatment was carried out to obtain an alkaline carbon dot solution; wherein, the carbon dot concentration of the alkaline carbon dot solution was 0.1 mg / mL, and the weight ratio of potassium hydroxide to carbon dots in the alkaline carbon dot solution was 25:1;

[0049] S2. Methyl silicate was added to the alkaline carbon dot solution containing potassium hydroxide and stirred and mixed at 45 °C for 8 hours to obtain a mixed solution; wherein, the weight ratio of methyl silicate to the alkaline carbon dot solution was 1:6;

[0050] S3. The oxidation catalytic material CAT-1 with a weight ratio of 25:100 was mixed with the mixed solution at 30 °C for 2 hours. The obtained mixture was transferred to a sealed autoclave and hydrothermally treated at a temperature of 150 °C and autogenous pressure for 48 hours. The obtained product was filtered, washed with water, naturally dried, and then calcined at 550 °C for 3 hours to obtain the modified oxidation catalytic material A1.

[0051] Example 2

[0052] The modified oxidation catalytic material A2 was prepared by the same method as in Example 1, except that in step S1, the weight ratio of water to potassium hydroxide was 100:23. In the obtained alkaline carbon dot solution, the carbon dot concentration was 0.15 mg / mL, and the weight ratio of potassium hydroxide to carbon dots was 260:1.

[0053] Example 3

[0054] The modified oxidation catalytic material A3 was prepared by the same method as in Example 1, except that in step S1, the weight ratio of the amount of water to potassium hydroxide was 100:0.007. In the obtained alkaline carbon dot solution, the concentration of carbon dots was 0.08 mg / mL, and the weight ratio of potassium hydroxide to the content of carbon dots was 3:1.

[0055] Example 4

[0056] S1. Add 800 mL of ultrapure water and ammonia water (the weight ratio of the amount of water to ammonia water is 100:12) to a 1000 mL beaker as the electrolyte. Place the anode graphite rod (diameter 8 mm, length 50 cm) and the cathode graphite rod (diameter 8 mm, length 50 cm) therein, and keep the distance between the anode graphite rod and the cathode graphite rod at 10 cm. Connect the anode graphite rod to the positive pole of the DC power supply and connect the cathode rod to the negative pole of the DC power supply, and apply a voltage of 40 V for electrolysis for 3 days. After completion, perform concentration treatment to obtain an alkaline carbon dot solution; wherein, the concentration of carbon dots in the alkaline carbon dot solution is 0.2 mg / mL, and the weight ratio of ammonia water to the content of carbon dots in the alkaline carbon dot solution is 76:1;

[0057] S2. Add methyl silicate to the alkaline carbon dot solution containing ammonia water and stir and mix at 60 °C for 12 hours to obtain a mixed solution; wherein, the weight ratio of methyl silicate to the amount of the alkaline carbon dot solution is 1:100;

[0058] S3. Mix the oxidation catalytic material CAT-1 with a weight ratio of 7:100 and the mixed solution at 50 °C for 3 hours. Transfer the obtained mixture to a sealed autoclave, perform hydrothermal treatment at a temperature of 180 °C and autogenous pressure for 72 hours. Filter the obtained product, wash it with water, dry it naturally, and then calcine it at 600 °C for 4 hours to obtain the modified oxidation catalytic material A4.

[0059] Example 5

[0060] The modified oxidation catalytic material A5 was prepared by the same method as in Example 1, except that in step S2, methyl silicate was added to the alkaline carbon dot solution containing potassium hydroxide and stirred and mixed at 15 °C for 8 hours to obtain a mixed solution; wherein, the weight ratio of methyl silicate to the amount of the alkaline carbon dot solution is 1:6.

[0061] Example 6

[0062] A6 was prepared in the same manner as in Example 1, except that in step S3, the oxidation catalytic material CAT-1 was mixed with the mixed solution at 20 °C for 2 hours, and the resulting mixture was transferred to a sealed autoclave and hydrothermally treated at 100 °C under autogenous pressure for 48 hours; the weight ratio of the mixed solution to the amount of the oxidation catalytic material CAT-1 was 100:65.

[0063] Comparative Example 1

[0064] The modified oxidation catalytic material DB1 was prepared in the same manner as in Example 1, except that step S1 was different. Step S1 in this comparative example was as follows: At normal temperature and pressure, 800 mL of ultrapure water was added to a 1000 mL beaker as the electrolyte. An anode graphite rod (diameter 8 mm, length 50 cm) and a cathode graphite rod (diameter 8 mm, length 50 cm) were placed therein, and the distance between the anode graphite rod and the cathode graphite rod was maintained at 8 cm. The anode graphite rod was connected to the positive pole of a DC power supply and the cathode rod was connected to the negative pole of the DC power supply, and a voltage of 15 V was applied for electrolysis for 4 days to obtain a carbon dot solution; the carbon dot concentration of the carbon dot solution was 0.08 mg / mL.

[0065] Comparative Example 2

[0066] The oxidation catalytic material was added to a potassium hydroxide solution and stirred and mixed evenly. The resulting mixture was placed in a sealed autoclave and hydrothermally treated at 150 °C under autogenous pressure for 48 hours. The obtained product was filtered, washed with water, naturally dried, and then calcined at 550 °C for 3 hours to obtain the modified oxidation catalytic material DB2.

[0067] Among them, the content of potassium hydroxide in the potassium hydroxide solution was the same as that of potassium hydroxide in the alkaline carbon dot solution in Example 1, and the amount of the oxidation catalytic material used, the amount of the potassium hydroxide solution used, and the amount of the alkaline carbon dot solution used were the same.

[0068] Comparative Example 3

[0069] The modified oxidation catalytic material DB3 was prepared in the same manner as in Example 1, except that steps S2 and S3 were different. In this comparative example, methyl silicate and the oxidation catalytic material were simultaneously added to the alkaline carbon dot solution containing potassium hydroxide, and stirred and mixed at 45 °C for 8 hours. The resulting mixture was transferred to a sealed autoclave and hydrothermally treated at 150 °C under autogenous pressure for 48 hours. The obtained product was filtered, washed with water, naturally dried, and then calcined at 550 °C for 3 hours to obtain the modified oxidation catalytic material DB3.

[0070] Test Example 1

[0071] The unmodified oxidation catalytic material CAT-1 and the modified oxidation catalytic materials prepared in the examples and comparative examples were used as catalysts for the catalytic oxidation reaction of cyclooctene.

[0072] The catalyst, the solvent methanol, cyclooctene, and an aqueous hydrogen peroxide solution (the content of H 2 O 2 in the aqueous hydrogen peroxide solution was 30% by weight) were sealed in a high-pressure reactor according to the weight ratio of catalyst: methanol: cyclooctene: aqueous hydrogen peroxide solution = 1:30:5:10. The reaction temperature was controlled at 70 °C, and the reaction was carried out at this temperature for 3 hours.

[0073] The product distribution of the reaction product was determined by a Varian 3400 gas chromatograph, and the capillary column (30 m × 0.25 mm) was FFAP. The test results are shown in Table 1.

[0074] The following formulas were used to calculate the raw material conversion rate and the target product selectivity:

[0075] Cyclooctene conversion rate = (molar amount of cyclooctene added before the reaction - molar amount of cyclooctene remaining after the reaction) / molar amount of cyclooctene added before the reaction × 100%,

[0076] Epoxycyclooctane selectivity = molar amount of epoxycyclooctane formed in the reaction / (molar amount of cyclooctene added before the reaction - molar amount of cyclooctene remaining after the reaction) × 100%.

[0077] Table 1

[0078]

[0079] As can be seen from Table 1, the modified oxidation catalytic material prepared by the method of the present invention has excellent catalytic performance. When it is used in the catalytic oxidation process of cyclooctene, the conversion rate of the raw material can be increased, especially the selectivity for the target product epoxycyclooctane can be improved.

[0080] Test Example 2

[0081] The unmodified oxidation catalytic material CAT-1 and the modified oxidation catalytic materials prepared in Example 1 and Comparative Example 1 were used as catalysts for the catalytic oxidation reaction of dimethylhexene.

[0082] The modified oxidation catalytic material, the solvent acetone, dimethylhexene (3,3-dimethyl-n-hexene), and an aqueous hydrogen peroxide solution (the content of H 2 O 2 in the aqueous hydrogen peroxide solution was 30% by weight) were sealed in a high-pressure reactor according to the weight ratio of modified oxidation catalytic material: acetone: dimethylhexene: aqueous hydrogen peroxide solution = 1:30:5:10. The reaction temperature was controlled at 80 °C, and the reaction was carried out at this temperature for 1 hour.

[0083] The product distribution of the reaction product was determined by an Agilent 7800 gas chromatograph. The capillary column (30 m × 0.25 mm) was FFAP. The test results are shown in Table 2.

[0084] The following formulas were used to calculate the raw material conversion rate and the target product selectivity:

[0085] Conversion rate of dimethylhexene = (molar amount of dimethylhexene added before reaction - molar amount of dimethylhexene remaining after reaction) / molar amount of dimethylhexene added before reaction × 100%,

[0086] Selectivity of dimethyloxirane = molar amount of dimethyloxirane formed in the reaction / (molar amount of dimethylhexene added before reaction - molar amount of dimethylhexene remaining after reaction) × 100%.

[0087] Table 2

[0088] Catalyst Number Conversion of Dimethylhexene, % Selectivity of Dimethyloxirane, % CAT-1 26 71 A1 45 80 DB1 17 35

[0089] As can be seen from Table 2, the modified oxidation catalytic material prepared by the method of the present invention has excellent catalytic performance. When it is used in the catalytic oxidation process of dimethylhexene, the conversion rate of the raw material can be increased, especially the selectivity for the target product dimethyloxirane can be increased.

[0090] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0091] In addition, it should be noted that, in the case of no contradiction, the various specific technical features described in the above specific embodiments can be combined in any appropriate way. To avoid unnecessary repetition, the present invention will not separately describe various possible combination ways.

[0092] In addition, any combination can be made between various different embodiments of the present invention, as long as it does not violate the idea of the present invention, it should also be regarded as the content disclosed by the present invention.

Claims

1. A method for preparing a modified oxidation catalytic material, the method comprises: S1. Connect a graphite formed body and a conductive substance to the positive and negative electrodes of a DC power supply respectively, and place them in an aqueous solution of an inorganic base. Electrolyze for 1 - 10 days at a voltage of 10 - 40 V to obtain an alkaline carbon dot solution; the content of the inorganic base in the aqueous solution of the inorganic base is 0.1 - 25% by weight; the weight ratio of the base to the carbon dots in the alkaline carbon dot solution is (10 - 500):1; S2. First mix a silicon source with the alkaline carbon dot solution to obtain a mixed solution; the conditions for the first mixing include: temperature is 20 - 100 °C, time is 1 - 24 hours; the weight ratio of the amount of the silicon source to the amount of the alkaline carbon dot solution is 1:(2 - 100); S3. After second mixing the mixed solution with the oxidation catalytic material, transfer the obtained mixture into a heat-resistant sealed container, carry out a hydrothermal reaction at 110 - 200 °C for 6 - 72 hours, collect the solid product and calcine it at 300 - 650 °C for 1 - 12 hours to obtain the modified oxidation catalytic material; the weight ratio of the amount of the mixed solution to the amount of the oxidation catalytic material is 100:(1 - 100); the oxidation catalytic material is selected from one or more of titanium-containing molecular sieves, iron-containing molecular sieves, vanadium-containing molecular sieves, and tin-containing molecular sieves.

2. The method according to claim 1, wherein, in step S1, the carbon dot concentration of the alkaline carbon dot solution is 0.01 - 2 mg / L.

3. The method according to claim 1, wherein, in step S2, the silicon source is selected from one or more of methyl silicate, ethyl silicate, propyl silicate, butyl silicate, methyl silane, ethyl silane, and propyl silane.

4. The method according to claim 1, wherein, in step S3, the conditions for the second mixing include: temperature is 20 - 60 °C, time is 0.1 - 6 hours; the conditions for the hydrothermal reaction include: temperature is 120 - 200 °C, time is 48 - 72 hours.

5. The method according to claim 1, wherein, the inorganic base is selected from one or more of ammonia, sodium hydroxide, potassium hydroxide, calcium hydroxide, and barium hydroxide.

6. A modified oxidation catalytic material prepared by using the method according to any one of claims 1 - 5.

7. The modified oxidation catalytic material according to claim 6, wherein, the mesopore volume of the modified oxidation catalytic material accounts for 50 - 75% of the total pore volume, and the ratio of the mesopore volume ratio to the mesopore specific surface area ratio is 1.5 - 2.

5.

8. The application of the modified oxidation catalytic material according to any one of claims 6 or 7 in the catalytic oxidation reaction of olefins, wherein, the olefin has 8 - 12 carbon atoms.

Images