A heteroatomic molecular sieve, its preparation method and use

Abstract

The present disclosure relates to a method for preparing a heteroatomic molecular sieve, wherein the method comprises: mixing a silicon source, a heteroatomic source, an organic template agent, graphene powder and water at a first temperature to obtain a mixed slurry; hydrolyzing the mixed slurry at a second temperature to obtain a hydrolysis solution; subjecting the hydrolysis solution to a hydrothermal reaction, and after solid-liquid separation, subjecting the recovered solid phase product to calcination; wherein the graphene powder is prepared by a supercritical carbon dioxide exfoliation method. The heteroatomic molecular sieve prepared by the present disclosure has a rich hierarchical pore structure, the accessibility of the reaction active center of the heteroatomic molecular sieve is high, has good catalytic reaction activity and activity stability, has high selectivity for target products, on the other hand, the heteroatomic molecular sieve prepared by the present disclosure has suitable ordered mesopores and / or macropores, which is conducive to the phenol hydroxylation reaction, has high phenol conversion rate, good catechol selectivity, and high catechol to ortho ratio.

Description

TECHNICAL FIELD

[0001] The present disclosure belongs to the field of heteroatomic molecular sieves, and particularly relates to a heteroatomic molecular sieve and a preparation method and use thereof. BACKGROUND

[0002] Heteroatomic molecular sieves such as titanium silicate molecular sieves can catalyze various types of organic oxidation reactions such as epoxidation of alkenes, partial oxidation of alkanes, oxidation of alcohols, hydroxylation of phenols, etc. in the oxidation reaction of organic matter, using non-polluting low-concentration hydrogen peroxide as an oxidant, avoiding the problems of complex process and environmental pollution in the oxidation process, having incomparable energy saving, economy and environmental friendliness compared with traditional oxidation systems, and having good reaction selectivity, thus having great industrial utilization prospects. However, the repeatability and stability of the current synthesis method of heteroatomic molecular sieves are not very ideal, and in particular, during the preparation process, heteroatomic oxide crystal phases are easily produced, thereby seriously affecting the reaction activity of the heteroatomic molecular sieve and the selectivity to the target product. SUMMARY

[0003] The purpose of the present application is to provide a heteroatomic molecular sieve and a preparation method and use thereof. The heteroatomic molecular sieve prepared by the present application has suitable ordered mesopores and / or macropores, the reaction active center of the heteroatomic molecular sieve has high accessibility, has good catalytic reaction activity and activity stability, and has high selectivity to the target product.

[0004] In order to achieve the above-mentioned purpose, the present application provides a method for preparing a heteroatomic molecular sieve, wherein the method comprises:

[0005] S1 mixing a silicon source, a heteroatomic source, an organic template agent, graphene powder and water at a first temperature to obtain a mixed slurry;

[0006] S2 hydrolyzing the mixed slurry at a second temperature to obtain a hydrolysis solution;

[0007] S3 performing a hydrothermal reaction on the hydrolysis solution, and after solid-liquid separation, performing calcination on the recovered solid-phase product;

[0008] Wherein, the graphene powder is prepared by a supercritical carbon dioxide exfoliation method, and the second temperature is higher than the first temperature.

[0009] Optionally, the D50 particle size of the graphene powder is 0.2-5 μm, the flake diameter is 1-2000 nm, the number of layers is 10 layers or less, and the specific surface area is 100-800 m 2 / g.

[0010] Optionally, the molar ratio of the silicon source calculated as SiO2, the heteroatom source calculated as heteroatom elements, the graphene powder calculated as carbon element, the organic template calculated as nitrogen element and water is 100: (0.1~5): (0.01~2): (5~50): (800~10000).

[0011] Optionally, in step S1, the silicon source is selected from an organic silicon source and / or an inorganic silicon source. Preferably, the organic silicon source is selected from one or more of methyl silicate, ethyl silicate, propyl silicate, and butyl silicate; preferably, the inorganic silicon source is selected from one or more of methylsilane, ethylsilane, and propylsilane;

[0012] The heteroatom source is selected from one or more of a titanium source, an iron source, a vanadium source and a tin source. Preferably, the heteroatom source is selected from one or more of a compound containing titanium, iron, vanadium and tin;

[0013] The organic template is selected from one or more of urea, quaternary ammonium base compounds, fatty amine compounds and alcohol amine compounds.

[0014] Optionally, step S1 further includes:

[0015] a. mixing a silicon source and a heteroatom source to obtain a first mixed material;

[0016] b. mixing the organic template, graphene powder and optional water to obtain a second mixed material;

[0017] c. Mixing the first mixed material and the second mixed material to obtain the mixed slurry.

[0018] Optionally, in step S1, the first temperature is 20 to 60° C., and the mixing time is 0.1 to 6 hours;

[0019] In step S2, the second temperature is 70 to 100° C., and the stirring time of the hydrolysis treatment is 3 to 24 hours;

[0020] Wherein, the temperature difference between the second temperature and the first temperature is 10 to 80°C;

[0021] In step S3, the conditions for the hydrothermal reaction include: being carried out under autogenous pressure, the hydrothermal reaction temperature is 110-200° C., and the hydrothermal reaction time is 6-96 hours; the conditions for the calcination include: the calcination temperature is 400-800° C., and the calcination time is 1-12 hours.

[0022] The second aspect of the present invention provides a heteroatom molecular sieve prepared by the method according to the first aspect of the present invention.

[0023] Optionally, the molar ratio of the heteroatom element to the silicon element in the heteroatom molecular sieve is (0.1-8):100.

[0024] Optionally, the BET specific surface area of ​​the heteroatom molecular sieve is 300 to 700 m 2 / g; total pore volume is 0.3~0.8cm 3 / g; mesopore volume is 0.2~0.6cm 3 / g; the ratio of mesopore volume to total pore volume is (0.5-0.9):1; the average particle size of the heteroatom molecular sieve is 0.1-1 μm.

[0025] The third aspect of the present invention provides use of the heteroatom molecular sieve described in the second aspect of the present invention in the hydroxylation reaction of phenol.

[0026] Through the above technical scheme, the preparation method provided by the present invention can effectively inhibit the formation of heteroatom oxide crystal phases during the preparation of heteroatom molecular sieves by adding graphene powder prepared by supercritical carbon dioxide exfoliation method during the preparation of heteroatom molecular sieves, and at the same time, the prepared heteroatom molecular sieve has appropriately ordered mesopores and macropores, effectively improving the accessibility of the reaction active centers of the heteroatom molecular sieves; on the other hand, the addition of powdered graphene during the hydrolysis process will promote the effective dispersion of titanium species and better combination with silicon species, further inhibiting the formation of heteroatom oxide crystal phases, thereby more specifically improving the diffusion rate of materials in the catalytic reaction of heteroatom molecular sieves, further improving the reaction activity and activity stability of the heteroatom molecular sieve, and the selectivity for the target product.

[0027] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the following detailed description, they are used to explain the present invention but do not constitute a limitation of the present invention. In the accompanying drawings:

[0029] Figure 1 The UV-Vis spectra of the samples prepared in Example 1 and Comparative Example 6 of the present invention are shown. DETAILED DESCRIPTION

[0030] The following describes the specific embodiments of the present disclosure in detail with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present disclosure and are not intended to limit the present disclosure.

[0031] The present disclosure provides a method for preparing a heteroatom molecular sieve, wherein the method comprises:

[0032] S1: mixing a silicon source, a heteroatom source, an organic template, graphene powder and water at a first temperature to obtain a mixed slurry;

[0033] S2 hydrolyzing the mixed slurry at a second temperature to obtain a hydrolyzed solution;

[0034] S3: performing a hydrothermal reaction on the hydrolysis solution, and after solid-liquid separation, calcining the recovered solid phase product.

[0035] Wherein, the graphene powder is prepared by a supercritical carbon dioxide exfoliation method, and the second temperature is higher than the first temperature.

[0036] The preparation method provided by the present invention can effectively inhibit the formation of heteroatom oxide crystal phases during the preparation of heteroatom molecular sieves by adding graphene powder prepared by supercritical carbon dioxide exfoliation method during the preparation of heteroatom molecular sieves, so that the prepared heteroatom molecular sieves have appropriately ordered mesopores and macropores, effectively improving the accessibility of the reaction active centers of the heteroatom molecular sieves; on the other hand, since the addition of powdered graphene during the hydrolysis process will promote the effective dispersion of titanium species and better combination with silicon species, it further inhibits the formation of heteroatom oxide crystal phases, thereby more specifically improving the diffusion rate of materials in the catalytic reaction of heteroatom molecular sieves, further improving the reaction activity and activity stability of the heteroatom molecular sieves, as well as the selectivity for the target product.

[0037] In a specific embodiment of the present disclosure, graphite is added to a reactor, the reactor is sealed, a gaseous intercalation medium is introduced into the reactor, and the pressure in the reactor is controlled at 1 to 200 atm by adjusting the gaseous intercalation medium intake rate. Under the conditions of this pressure and stirring, the system temperature is raised to 25 to 500° C. to carry out a molecular intercalation reaction. After the reaction is completed, the pressure is rapidly released so that the pressure in the reactor is rapidly reduced to half or less of the pressure in the reactor within 0.1 s. Then, the gas is released to normal pressure, and the buffer tank is opened to obtain graphene powder.

[0038] In the above embodiment, the graphene powder prepared by supercritical carbon dioxide exfoliation method has a more uniform particle size distribution and fewer layers, which can effectively inhibit the formation of heteroatom oxide crystal phase during the preparation of heteroatom molecular sieves, and make the prepared heteroatom molecular sieve produce appropriately ordered mesopores and / or macropores. On the one hand, it can effectively improve the accessibility of the reaction active centers of the heteroatom molecular sieve; on the other hand, it can further specifically improve the diffusion rate of materials in the catalytic reaction of the heteroatom molecular sieve, thereby improving the reaction activity and activity stability of the heteroatom molecular sieve, as well as the selectivity for the target product.

[0039] In a specific embodiment of the present disclosure, the graphene powder has a D50 particle size of 0.2 to 5 μm, preferably 0.5 to 2 μm, a sheet diameter of 1 to 2000 nm, preferably 10 to 1000 nm, a layer number of 10 or less, preferably 8 or less, and a specific surface area of ​​100 to 800 m 2 / g, preferably 150 to 600 m 2 / g.

[0040] In the above embodiment, by introducing the graphene powder prepared by the present disclosure into the reaction mixture for synthesizing the heteroatom molecular sieve, the accessibility of the reaction active centers of the heteroatom molecular sieve can be further improved, so that the heteroatom molecular sieve has better catalytic reaction activity and activity stability, as well as higher target product selectivity.

[0041] In a specific embodiment of the present disclosure, the molar ratio of the silicon source calculated as SiO2, the heteroatom source calculated as heteroatom elements, the graphene powder calculated as carbon element, the organic template calculated as nitrogen element and water is 100: (0.1~5): (0.01~2): (5~50): (800~10000), preferably 100: (0.2~2.5): (0.05~1): (10~25): (1200~5000).

[0042] In a specific embodiment of the present disclosure, in step S1, in step S1, the silicon source is selected from an organic silicon source and / or an inorganic silicon source. Preferably, the organic silicon source is selected from one or more of methyl silicate, ethyl silicate, propyl silicate, and butyl silicate; preferably, the inorganic silicon source is selected from one or more of methylsilane, ethylsilane, and propylsilane;

[0043] The heteroatom source is selected from one or more of a titanium source, an iron source, a vanadium source, and a tin source. Preferably, the heteroatom source is selected from one or more of compounds containing titanium, iron, vanadium, and tin. Among them, the titanium-containing compound can be selected from one or more of titanate, titanium tetrachloride, and titanyl sulfate, preferably one or more of tetrabutyl titanate, tetraisopropyl titanate, and titanyl sulfate; the iron-containing compound can be selected from one or more of ferric nitrate, ferric hydroxide, ferric oxide, ferric chloride, ferric sulfate, ferric acetylacetonate, ferric isopropoxide, ferric phosphate, ferric acetate, and ferric acid and its salts, preferably one or more of ferric hydroxide, ferric oxide, ferric chloride, ferric sulfate, and ferric acid; the vanadium-containing compound can be selected from one or more of vanadic acid, ammonium vanadate, sodium vanadate, and vanadium oxide, preferably one or more of ammonium vanadate, sodium vanadate, and vanadium oxide; the tin-containing compound can be selected from one or more of ammonium stannate, tin tetrachloride, tin sulfate, and tin oxide, preferably one or more of tin tetrachloride and tin oxide;

[0044] The organic template is selected from one or more of urea, quaternary ammonium base compounds, fatty amine compounds and alcoholamine compounds, wherein the quaternary ammonium base compound can be selected from one or more of tetraethylammonium hydroxide, tetrapropylammonium hydroxide and tetrabutylammonium hydroxide; the fatty amine compound can be selected from one or more of ethylamine, n-butylamine, butanediamine and hexamethylenediamine; the alcoholamine compound can be selected from one or more of monoethanolamine, diethanolamine and triethanolamine.

[0045] In a specific embodiment of the present disclosure, step S1 further includes:

[0046] a. mixing a silicon source and a heteroatom source to obtain a first mixed material;

[0047] b. mixing the organic template, graphene powder and optional water to obtain a second mixed material;

[0048] c. Mixing the first mixed material and the second mixed material to obtain the mixed slurry.

[0049] In the present invention, by adopting the mixing order in the above-mentioned embodiment, adding powdered graphene during the hydrolysis process can promote the effective dispersion of titanium species and better combination with silicon species, further inhibiting the formation of heteroatom oxide crystal phases, thereby more specifically improving the diffusion rate of materials in the heteroatom molecular sieve catalytic reaction, further improving the reaction activity and activity stability of the heteroatom molecular sieve, and the selectivity for the target product.

[0050] In a specific embodiment of the present disclosure, in step S1, the first temperature is 20 to 60°C, preferably 30 to 50°C, and the mixing time is 0.1 to 6 hours, preferably 0.5 to 3 hours;

[0051] In step S2, the second temperature is 70 to 100° C., preferably 75 to 95° C., and the stirring time of the hydrolysis treatment is 3 to 24 hours, preferably 6 to 12 hours;

[0052] Wherein, the temperature difference between the second temperature and the first temperature is 10 to 80°C, preferably 15 to 65°C;

[0053] In step S3, the conditions for the hydrothermal reaction include: being carried out under autogenous pressure, the hydrothermal reaction temperature is 110-200° C., preferably 130-180° C., and the hydrothermal reaction time is 6-96 hours, preferably 12-72 hours; the conditions for the calcination include: the calcination temperature is 400-800° C., preferably 500-700° C., and the calcination time is 1-12 hours, preferably 2-6 hours.

[0054] A second aspect of the present disclosure provides a heteroatom molecular sieve prepared according to the method described in the first aspect of the present disclosure.

[0055] In a specific embodiment of the present disclosure, the molar ratio of the heteroatom element to the silicon element in the heteroatom molecular sieve is (0.1-8):100, preferably (0.5-4):1.

[0056] In a specific embodiment of the present disclosure, the BET specific surface area of ​​the heteroatom molecular sieve is 300 to 700 m 2 / g, preferably 400 to 600 m 2 / g; total pore volume is 0.3~0.8cm 3 / g, preferably 0.35 to 0.7 cm 3 / g; mesopore volume is 0.2~0.6cm 3 / g, preferably 0.25 to 0.5 cm 3 / g; the ratio of mesopore volume to total pore volume is (0.5-0.9):1, preferably (0.6-0.8):1; the average particle size of the heteroatom molecular sieve is 0.1-1 μm, preferably 0.2-0.5 μm.

[0057] The heteroatom molecular sieve prepared in the present invention has a rich multi-level pore structure, which makes the reaction active center of the heteroatom molecular sieve highly accessible, has good catalytic reaction activity and activity stability, and has high target product selectivity. On the other hand, the heteroatom molecular sieve prepared in the present invention has appropriately ordered mesopores and / or macropores, which are conducive to the phenol hydroxylation reaction, with high phenol conversion rate, high diphenol to ortho ratio, and good diphenol selectivity.

[0058] The third aspect of the present disclosure provides use of the heteroatom molecular sieve described in the second aspect of the present invention in a phenol hydroxylation reaction.

[0059] In the present disclosure, the reaction conditions for the phenol hydroxylation reaction using the heteroatom molecular sieve as a catalyst include: a reaction temperature of 50 to 80° C. and a reaction time of 1 to 4 hours.

[0060] The present invention is further illustrated below by way of examples, but the present invention is not limited thereto.

[0061] Example 1

[0062] a. Add 1 g of graphite into the reactor, introduce a gaseous intercalation medium (carbon dioxide) into the reactor, and control the pressure in the reactor at 1 atm by adjusting the gaseous intercalation medium intake. Under this pressure and stirring conditions, raise the system temperature to 200°C to carry out a molecular intercalation reaction. After reacting for 0.5 h, rapidly release the pressure to rapidly reduce the pressure in the reactor to half or less of the pressure in the reactor within 0.1 s. Then, release the gas to normal pressure, open the buffer tank, and obtain 0.9 g of graphene powder. The D50 particle size of the graphene powder is 2.8 μm, recorded as CUP1.

[0063] b. Mixing 30 g of ethyl silicate and an appropriate amount of tetrabutyl titanate with stirring at 30° C. for 0.5 hour at a stirring speed of 600 rpm to obtain a first mixed material;

[0064] c. Mixing an appropriate amount of graphene powder CUP1 with a tetrapropylammonium hydroxide aqueous solution (25% mass concentration) at 35° C. for 2 hours at a stirring speed of 300 rpm to obtain a second mixed material;

[0065] d. Mixing the first mixed material with the second mixed material, stirring and mixing at 75° C. for 2 hours at a stirring speed of 500 rpm to obtain a third mixed material, wherein the addition ratio of the above materials is: the molar ratio of silicate (calculated as SiO2), titanate (calculated as TiO2), graphene (calculated as C), tetrapropylammonium hydroxide (calculated as N) and water is 100:3:0.2:15:5000;

[0066] e After the third mixed material was further mixed at 80°C for 5 hours, it was transferred to a sealed high-pressure reactor and hydrothermally treated at a temperature of 170°C and autogenous pressure for 48 hours to obtain a sample. The obtained sample was filtered, washed, and naturally dried, and then calcined at 500°C for 3 hours to obtain a heteroatom molecular sieve, which was recorded as A1.

[0067] Example 2

[0068] The method of Example 1 is adopted, except that the molar ratio of silicate (calculated as SiO2), titanate, graphene, tetrapropylammonium hydroxide (calculated as N) and water is 100:3:0.1:20:3000; in step e, the third mixed material is further mixed at 70°C for 12 hours to obtain a heteroatom molecular sieve, which is recorded as A2.

[0069] Example 3

[0070] The method of Example 1 was adopted, except that, in step c, the same amount of graphene powder CUP2 was used, and the D50 particle size of the graphene powder was 0.5 μm, to obtain a heteroatom molecular sieve, which was recorded as A3.

[0071] 5 g of graphite was added to the reactor, and a gaseous intercalation medium (carbon dioxide) was introduced into the reactor. The pressure in the reactor was controlled at 100 atm by adjusting the air intake of the gaseous intercalation medium. Under this pressure and stirring conditions, the system temperature was raised to 200° C. to carry out a molecular intercalation reaction. After the reaction lasted for 1 hour, the pressure was rapidly released to reduce the pressure in the reactor to half or less of the pressure in the reactor within 0.1 second. The gas was then released to normal pressure, and the buffer tank was opened to obtain 4.6 g of graphene powder, which was recorded as CUP2.

[0072] Example 4

[0073] The method of Example 2 was adopted, except that, in step c, the same amount of graphene powder CUP3 was used, and the D50 particle size of the graphene powder was 10 μm, to obtain a heteroatom molecular sieve, which was recorded as A4.

[0074] 10 g of graphite was added to the reactor, and a gaseous intercalation medium (carbon dioxide) was introduced into the reactor. The pressure in the reactor was controlled at 200 atm by adjusting the air intake of the gaseous intercalation medium. Under this pressure and stirring conditions, the system temperature was raised to 300° C. to carry out a molecular intercalation reaction. After reacting for 4 hours, the pressure was rapidly released to quickly reduce the pressure in the reactor to half or less of the pressure in the reactor within 0.1 seconds. The gas was then released to normal pressure, and the buffer tank was opened to obtain 9.1 g of graphene powder, which was recorded as CUP3.

[0075] Example 5

[0076] The method of Example 2 was adopted, except that, in step b, the mixture was stirred at 60° C. for 1 hour at a stirring speed of 1000 rpm; in step c, the mixture was stirred at 60° C. for 0.1 hour at a stirring speed of 100 rpm; and in step e, the mixture was hydrothermally treated at a temperature of 140° C. and autogenous pressure for 6 hours to obtain a heteroatom molecular sieve, which was recorded as A5.

[0077] Example 6

[0078] The method of Example 2 was adopted, except that, in step b, the same amount of ethyl silicate and ferric nitrate were stirred and mixed at 80° C. for 4 hours; in step c, the same amount of graphene and tetraethylammonium hydroxide were stirred and mixed at 85° C. for 8 hours at a stirring speed of 500 rpm; wherein the molar ratio of ethyl silicate (as SiO2), ferric nitrate, graphene, tetraethylammonium hydroxide (as N) and water was 100:1:0.2:40:1000, to obtain a heteroatom molecular sieve, recorded as A6.

[0079] Example 7

[0080] The method of Example 1 is adopted, except that, in step c, the first mixed material is mixed with the same amount of tetrapropylammonium hydroxide aqueous solution, and then mixed with graphene powder CUP1 to obtain a second mixed material, thereby obtaining a heteroatom molecular sieve, which is recorded as A7.

[0081] Comparative Example 1

[0082] The method of Example 1 was adopted, except that no graphene powder was added, to obtain a heteroatom molecular sieve, which was recorded as DB1.

[0083] Comparative Example 2

[0084] The method of Example 1 was adopted, except that the same amount of graphene powder CUP4 (purchased from Changzhou Sixth Element Materials Technology Co., Ltd., product number SE1233) was prepared by redox method, the D50 particle size of the graphene powder was 9 μm, and a heteroatom molecular sieve was obtained, which was recorded as DB2.

[0085] Comparative Example 3

[0086] The method of Example 1 was adopted, except that the same amount of graphene powder CUP5 (purchased from Di Chuang (Suzhou) New Materials Technology Co., Ltd., product number DCRGO-200) was prepared by redox method, the D50 particle size of the graphene powder was 10 μm, and the heteroatom molecular sieve was obtained, which was recorded as DB3.

[0087] Comparative Example 4

[0088] The method of Example 1 was adopted, except that the same amount of graphene powder CUP6 (purchased from Deyang Encarbon Technology Co., Ltd., product number HE-01) was prepared by solid-phase intercalation exfoliation method, and the D50 particle size of the graphene powder was 12 μm, to obtain a heteroatom molecular sieve, which was recorded as DB4.

[0089] Comparative Example 5

[0090] The method of Example 1 was adopted, except that in step c, the same amount of carbon nanotubes (purchased from Shandong Dazhan Nanomaterial Co., Ltd., product number GT-300) was used, the diameter of the carbon nanotubes was 10-15 nm, and the length was 3-12 μm, to obtain a heteroatom molecular sieve, which was recorded as DB5.

[0091] Comparative Example 6

[0092] a. Add 1 g of graphite into the reactor, introduce a gaseous intercalation medium (carbon dioxide) into the reactor, and control the pressure in the reactor at 1 atm by adjusting the gaseous intercalation medium intake. Under this pressure and stirring conditions, raise the system temperature to 200°C to carry out a molecular intercalation reaction. After reacting for 0.5 h, rapidly release the pressure to rapidly reduce the pressure in the reactor to half or less of the pressure in the reactor within 0.1 s. Then, release the gas to normal pressure, open the buffer tank, and obtain 0.9 g of graphene powder. The D50 particle size of the graphene powder is 2.8 μm, recorded as CUP1.

[0093] b. 30 g of ethyl silicate, an appropriate amount of tetrabutyl titanate and a tetrapropylammonium hydroxide aqueous solution (25% by mass) were stirred and mixed at 35° C. for 2 hours at a stirring speed of 300 rpm to obtain a first mixed material;

[0094] c. After continuing to mix the first mixed material at 80° C. for 5 hours, an appropriate amount of graphene powder CUP1 was added and stirred at 75° C. for 2 hours at a stirring speed of 500 rpm to obtain a second mixed material, wherein the molar ratio of silicate (calculated as SiO2), titanate, graphene, tetrapropylammonium hydroxide (calculated as N) and water was 100:3:0.2:15:5000;

[0095] e. The second mixed material was transferred to a sealed high-pressure reactor and hydrothermally treated at a temperature of 170°C and autogenous pressure for 48 hours to obtain a sample. The obtained sample was filtered, washed, naturally dried, and then calcined at 500°C for 3 hours to obtain a heteroatom molecular sieve, which was recorded as DB6.

[0096] Test Case

[0097] The heteroatom molecular sieves prepared in Examples 1 to 7 and Comparative Examples 1 to 6 were used as catalysts to carry out phenol hydroxylation reaction, and the specific steps were as follows:

[0098] The catalyst, solvent water, phenol and hydrogen peroxide aqueous solution (the H2O2 content in the hydrogen peroxide aqueous solution is 30 weight%) are sealed in a high-pressure reactor according to the weight ratio of catalyst: water: phenol: hydrogen peroxide aqueous solution = 1:30:20:5, and reacted at 60°C for 3 hours.

[0099] The reagents used in this test example were all commercially available chemically pure reagents. The concentrations of the substances after the reaction were measured by an Agilent 6890N gas chromatograph. The analytical chromatographic column used was a capillary column (30 m×0.25 mm) HP-1.

[0100] The raw material conversion rate and target product selectivity in the examples and comparative examples were calculated according to the following formulas (1) and (2), respectively:

[0101]

[0102]

[0103] The test results are shown in Table 1.

[0104] Table 1

[0105]

[0106]

[0107] According to the test results in Table 1, it can be seen that the reactive centers of the heteroatom molecular sieve prepared by the preparation method provided by the present disclosure are highly accessible, have good catalytic reaction activity and activity stability, and have high selectivity for the target product.

[0108] It can be seen from the test results of Examples 1 to 4 that when the preparation method, the order of adding the components, the molar ratio of the components, and the particle size of the graphene powder are all within the specified range of the present disclosure, the performance of the product prepared by the present disclosure can be further improved; it can be seen from the test results of Examples 5 to 7 that when the particle size of the graphene powder, the reaction parameters and conditions, and the mixing order of the components are controlled within the preferred range of the present disclosure, the conversion rate of the heteroatom molecular sieve prepared by the present disclosure to phenol can be further improved, so that the heteroatom molecular sieve has better catalytic reaction activity, activity stability and higher target product selectivity.

[0109] From the test results of Comparative Examples 1 to 6, it can be seen that since no graphene powder is added during the preparation process of Comparative Example 1, the heteroatom oxides produced during the preparation of the heteroatom molecular sieve cannot be effectively suppressed, resulting in poor accessibility of the reactive centers of the prepared heteroatom molecular sieve, and the diffusion rate of the material in the catalytic reaction of the heteroatom molecular sieve is reduced, thereby the reaction activity, activity stability and selectivity of the heteroatom molecular sieve to the target product are all worse than those of Examples 1 to 7; since the graphene powder used in Comparative Examples 2 to 3 is prepared by redox method, the graphene powder used in Comparative Example 4 is The graphene powder used is prepared by solid-phase intercalation exfoliation method, which makes the particle size distribution and layer number distribution of the prepared heteroatom molecular sieve uneven, and cannot effectively inhibit the formation of heteroatom oxide crystal phase, resulting in poor reaction activity, activity stability and selectivity of the heteroatom molecular sieve for the target product; since the graphene powder is replaced by carbon nanotubes in Comparative Example 5, the prepared heteroatom molecular sieve cannot inhibit the formation of heteroatom oxide crystal phase, resulting in the conversion rate of heteroatom molecular sieve to phenol and the ratio of hydroquinone to ortho-phenol being significantly worse than those of the embodiments of the present disclosure; Figure 1As shown, since graphene powder is added after the hydrolysis treatment in Comparative Example 6, the prepared molecular sieve DB6 has a characteristic peak of heteroatom oxide at around 330 nm compared with the molecular sieve A1 prepared in Example 1, and the absorption peak intensity generated at around 210 nm is higher, resulting in the inability to effectively disperse the titanium species and effectively combine with the silicon species during the preparation process of the heteroatom molecular sieve, making it impossible to effectively suppress the heteroatom oxide crystal phase, and the reaction activity, activity stability and target product selectivity of the heteroatom molecular sieve are poor.

[0110] The preferred embodiments of the present invention are described in detail above in conjunction with the accompanying drawings. However, the present invention is not limited to the specific details in the above embodiments. Within 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 fall within the scope of protection of the present invention.

[0111] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0112] In addition, the various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A method for preparing a heteroatom molecular sieve, wherein: The method includes: S1: mixing a silicon source, a heteroatom source, an organic template, graphene powder and water at a first temperature to obtain a mixed slurry; S2 hydrolyzing the mixed slurry at a second temperature to obtain a hydrolyzed solution; S3: performing a hydrothermal reaction on the hydrolyzed solution, and after solid-liquid separation, calcining the recovered solid phase product; Wherein, the graphene powder is prepared by supercritical carbon dioxide exfoliation method, and the second temperature is higher than the first temperature; The heteroatom source is selected from one or more of a titanium source, an iron source, a vanadium source and a tin source.

2. The method according to claim 1, wherein The graphene powder has a D50 particle size of 0.2-5 μm, a sheet diameter of 1-2000 nm, a layer number of less than 10 layers, and a specific surface area of ​​100-800 m 2 / g.

3. The method according to claim 1, wherein The molar ratio of the silicon source calculated as SiO2, the heteroatom source calculated as heteroatom elements, the graphene powder calculated as carbon element, the organic template calculated as nitrogen element and water is 100: (0.1~5): (0.01~2): (5~50): (800~10000).

4. The method according to claim 1, wherein In step S1, the silicon source is selected from an organic silicon source and / or an inorganic silicon source; The heteroatom source is selected from one or more compounds containing titanium, iron, vanadium and tin; The organic template is selected from one or more of urea, quaternary ammonium base compounds, fatty amine compounds and alcohol amine compounds.

5. The method according to claim 4, wherein The organic silicon source is selected from one or more of methyl silicate, ethyl silicate, propyl silicate and butyl silicate.

6. The method according to claim 4, wherein: The inorganic silicon source is selected from one or more of methylsilane, ethylsilane and propylsilane.

7. The method according to claim 1, wherein Step S1 further includes: a. mixing a silicon source and a heteroatom source to obtain a first mixed material; b. mixing the organic template, graphene powder and optionally water to obtain a second mixed material; c. Mixing the first mixed material and the second mixed material to obtain the mixed slurry.

8. The method according to claim 1, wherein In step S1, the first temperature is 20-60°C and the mixing time is 0.1-6 hours; In step S2, the second temperature is 70-100° C., and the stirring time of the hydrolysis treatment is 3-24 hours; Wherein, the temperature difference between the second temperature and the first temperature is 10-80°C; In step S3, the hydrothermal reaction conditions include: being carried out under autogenous pressure, the hydrothermal reaction temperature is 110-200° C., and the hydrothermal reaction time is 6-96 hours; the calcination conditions include: the calcination temperature is 400-800° C., and the calcination time is 1-12 hours.

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

10. The heteroatom molecular sieve according to claim 9, wherein The molar ratio of the heteroatom element to the silicon element in the heteroatom molecular sieve is (0.1-8):

100.

11. The heteroatom molecular sieve according to claim 9, wherein The BET specific surface area of ​​the heteroatom molecular sieve is 300-700 cm 2 / g; total pore volume is 0.3~0.8cm 3 / g; mesopore volume is 0.2~0.6cm 3 / g; the ratio of mesopore volume to total pore volume is (0.5~0.9):1; the average particle size of the heteroatom molecular sieve is 0.1~1μm.

12. Use of the heteroatom molecular sieve according to any one of claims 9 to 11 in the hydroxylation reaction of phenol.

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