A multi-stage pore MFI molecular sieve and its preparation method and application

Abstract

The present invention discloses a multi-level pore MFI molecular sieve and its preparation method and application. The multi-level pores in the molecular sieve include micropores and mesopores, and the specific surface area of ​​the molecular sieve is 500-600m 2 / g, total pore volume of 0.30~0.60cm 3 / g, micropore volume is 0.15~0.30cm 3 / g, and its preparation method includes: first, synthesizing a mesoporous precursor silicon material using a first template, then mixing a second template with an aluminum source and an alkali source, and then, under the action of water vapor, performing dry gel conversion to obtain a multi-level pore MFI molecular sieve. The MFI molecular sieve of the present invention is used in the reaction of cyclopentane hydration to produce cyclopentanol, and has the characteristics of high activity, good stability, and good selectivity.

Description

Technical Field

[0001] The present invention relates to the field of molecular sieve preparation, and in particular to a multi-stage pore MFI molecular sieve and a preparation method and application thereof. Background Art

[0002] ZSM-5 zeolite is a typical aluminum-containing MFI topology zeolite, widely used as a catalytic material in coal chemical and petrochemical industries. The structural unit of ZSM-5 zeolite consists of eight five-membered rings with zigzag ten-membered circular channels. The ten-membered ring channels parallel to the a-axis of the unit cell have an elliptical pore size of 0.54 × 0.56 nm; the ten-membered ring channels parallel to the c-axis are elliptical, with a pore size of 0.51 × 0.55 nm. The pore diameter at the channel intersection is approximately 0.94 nm.

[0003] ZSM-5 molecular sieves are excellent solid acid catalysts and catalyst supports due to their unique pore structure, excellent ion exchange performance and shape selectivity, good thermal and hydrothermal stability, strong acidity, wide Si / Al distribution range, and wide adjustable acidity range. The pore size of ZSM-5 molecular sieves is close to the molecular dynamics diameters of benzene, toluene, and xylene, giving them exceptional shape-selective catalytic properties and applications in aromatization reactions of hydrocarbons and alcohols. However, ZSM-5 molecular sieves possess only a microporous structure with narrow pores, which can easily become clogged during catalytic reactions, leading to catalyst deactivation. They are also prone to side reactions such as ring opening and coupling dehydration of olefins with product alcohols, resulting in low catalytic stability and product selectivity. Summary of the Invention

[0004] The purpose of the present invention is to provide a multi-level pore MFI molecular sieve and its preparation method and application in response to the defects of the prior art. The MFI molecular sieve contains multi-level pores and is used in the cyclopentene hydration reaction, and has the characteristics of high activity, good selectivity and few by-products.

[0005] The first aspect of the present invention provides a multi-level pore MFI molecular sieve, wherein the multi-level pores include micropores and mesopores, and the specific surface area of ​​the molecular sieve is 500-600m 2 / g, total pore volume of 0.30~0.60cm 3 / g, micropore volume is 0.15~0.30cm 3 / g.

[0006] Furthermore, in the multi-level pores, micropores refer to pores with a pore diameter of 0.5 to 0.8 nm, and mesopores refer to pores with a pore diameter of 2.0 to 50.0 nm.

[0007] Furthermore, the average pore size of the molecular sieve is 2.8 to 4.0 nm.

[0008] Furthermore, the pore distribution of the molecular sieve is as follows: the volume of pores with a pore diameter less than 2.0 nm accounts for 15% to 45% of the total pore volume, the volume of pores with a pore diameter of 2.0 to 5.0 nm accounts for 20% to 40% of the total pore volume, the volume of pores with a pore diameter of 5.0 to 20.0 nm accounts for 15% to 30% of the total pore volume, and the volume of pores with a pore diameter greater than 20.0 nm to 50.0 nm accounts for less than 15% of the total pore volume, preferably 8% to 14%.

[0009] Furthermore, the relative crystallinity of the molecular sieve is 60-80%.

[0010] The second aspect of the present invention provides a method for preparing a multi-stage pore MFI molecular sieve, comprising the following steps:

[0011] (1) mixing a silicon source, a first template, anhydrous ethanol, and water to obtain a gel, adjusting the pH value of the gel to 8-12, and aging the gel to obtain a precursor material;

[0012] (2) mixing the precursor material obtained in step (1), the aluminum source, the second template, and the alkali source, and placing them on the top of a crystallization kettle, adding a certain amount of water to the bottom of the crystallization kettle, and crystallizing to obtain an intermediate crystalline material;

[0013] (3) calcining the intermediate crystalline material obtained in step (2) to obtain the multi-level pore MFI molecular sieve.

[0014] Furthermore, in step (1), the molar ratio of the silicon source calculated as SiO2, the first template, anhydrous ethanol and H2O is 1: (0.1-0.5): (3-10): (20-100).

[0015] Furthermore, in step (1), the silicon source is selected from at least one of silica sol, solid silicon oxide, white carbon black or silicate.

[0016] Furthermore, in step (1), the first template is selected from at least one of dodecylamine, tetradecylamine, hexadecylamine or octadecylamine.

[0017] Furthermore, in step (1), the aging is carried out under stirring, the aging temperature is 10 to 40° C., and the aging time is 12 to 36 hours.

[0018] Furthermore, in step (1), the pH can be adjusted by adding ammonia water.

[0019] Furthermore, in step (1), after the aging step is completed, the precursor material product can be separated from the obtained mixture by any conventional separation method, such as filtering, washing and drying. Here, the filtering, washing and drying can be carried out in any conventional manner known in the art. The drying temperature can be selected from 80 to 200°C, preferably 100 to 150°C; the drying time can be 2 to 24 hours, preferably 5 to 10 hours. The drying can be carried out under normal pressure or under reduced pressure. To save energy, normal pressure is often selected.

[0020] Furthermore, in step (2), the aluminum source is selected from at least one of aluminum hydroxide, sodium aluminate, aluminum isopropoxide, aluminum nitrate, aluminum sulfate, kaolin or montmorillonite.

[0021] Furthermore, in step (2), the alkali source is selected from at least one alkali metal hydroxide.

[0022] Furthermore, in step (2), the second template is selected from at least one of tetrapropylammonium bromide, dimethylamine, trimethylamine, ethylenediamine, hexamethylenediamine, cyclohexylamine, isopropylamine, diethylamine, triethylamine or n-butylamine.

[0023] Furthermore, in step (2), the molar ratio of the precursor material calculated as SiO2, the aluminum source calculated as Al2O3, the second template, the alkali source calculated as OH- and water is 1: (0.02-0.1): (0.05-0.5): (0.05-0.15): (1-5).

[0024] Furthermore, in step (2), the crystallization conditions are as follows: the crystallization temperature is 130-200° C., and the crystallization time is 1-14 days. Preferably, the crystallization temperature is 150-190° C., and the crystallization time is 5-7 days.

[0025] Furthermore, in step (2), after the crystallization step is completed, the intermediate crystalline material product can be separated from the obtained mixture by any conventional separation method, such as filtering, washing and drying. Here, the filtering, washing and drying can be carried out in any conventional manner known in the art. The drying temperature can be selected from 80 to 200°C, preferably 100 to 150°C; the drying time can be 2 to 24 hours, preferably 5 to 10 hours. The drying can be carried out under normal pressure or under reduced pressure. To save energy, normal pressure is usually selected.

[0026] Furthermore, in step (3), the calcination conditions are as follows: the calcination temperature is 400-550° C., the calcination time is 5-10 hours, and the atmosphere is an oxygen-containing gas (such as air).

[0027] The third aspect of the present invention provides an application of a multi-level pore MFI molecular sieve, a multi-level pore MFI molecular sieve prepared according to any of the aforementioned preparation methods, or an application of a multi-level pore MFI molecular sieve according to any of the aforementioned methods.

[0028] Furthermore, the application is one or more of olefin hydration, aromatic alkylation, catalytic cracking of C4 and above alkanes or alkenes, aromatic disproportionation, and aromatization of hydrocarbons and alcohols.

[0029] Furthermore, the application is olefin hydration reaction.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] The MFI structured molecular sieve of the present invention has multi-level pores, including micropores and mesopores, and the catalyst has a large specific surface area. The specific pore structure is suitable for olefin hydration reactions and has the characteristics of high activity, good selectivity and few by-products in such reactions.

[0032] The method for preparing the multi-level pore MFI molecular sieve of the present invention is a technical solution that uses a first template to synthesize a mesoporous silicon precursor material, then mixes a second template with an aluminum source and an alkali source, and undergoes dry gel conversion under the action of water vapor. This method utilizes the fact that the microporous small molecule organic amine template has a relatively weak guiding ability during the crystallization process of the molecular sieve, so that the mesoporous precursor is converted in situ into an MFI molecular sieve with a monolithic structure. The MFI molecular sieve prepared by the method of the present invention retains most of the mesoporous structure of the precursor and also produces a microporous structure unique to the MFI structure during the crystallization process. These specific structural features give the molecular sieve the advantages of good catalytic activity, faster material diffusion rate, more stable catalyst performance, and fewer by-products in the catalytic olefin hydration reaction. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is the XRD spectrum of the multi-level pore MFI molecular sieve prepared in Example 1 of the present invention;

[0034] Figure 2 This is the N2 adsorption-desorption curve of the multi-level pore MFI molecular sieve prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0035] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments of the present invention and the accompanying drawings. Obviously, the embodiments described are part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0036] The present invention uses the following equipment to characterize the prepared multi-level pore MFI molecular sieve, and the following examples all use the same characterization equipment and testing methods.

[0037] In the present invention, a Japanese Rigaku-Ultima X-ray diffractometer is used to analyze the molecular sieve crystal phase. The XRD test conditions are as follows: CuKα radiation, wavelength λ = 0.15432 nm; X-ray diffraction pattern scanning range 2θ = 5° to 50°, scanning speed 10° / min, operating voltage 40 kV, and current 40 mA.

[0038] In the present invention, N2 physical adsorption is used to determine the average pore volume and total pore volume of the molecular sieve, and the test method is as follows: the specific surface area (BET) and pore volume of the sample are analyzed using the Autosorb-I automatic adsorption specific surface and porosity analyzer of Quantachrome Company of the United States, wherein the cold trap is liquid nitrogen and the adsorption medium is high-purity nitrogen; the adsorption isotherm equation of the HK model is used to analyze the low-pressure section of the adsorption isotherm to obtain the pore size distribution curve of the molecular sieve; the specific surface area and pore volume of the molecular sieve are calculated respectively by the BET method and the t-plot method.

[0039] In the present invention, gas chromatography is used to analyze the product. A certain amount of the reaction mixture is injected into the gas chromatograph inlet, passed through the chromatographic column, detected by FID, and quantitatively analyzed by external standard method. The gas chromatograph used is a 7890 gas chromatograph produced by Agilent, and the analytical chromatographic column used is an INNOWAX column.

[0040] The calculation formulas for conversion rate and selectivity in the application examples of the present invention are as follows:

[0041] Cyclopentene conversion rate X HPE = mass percentage of each chromatographic product and by-product / (mass percentage of each chromatographic product and by-product + mass percentage of cyclopentene) × 100%;

[0042] Selectivity of cyclopentanol S HPA = cyclopentanol mass percentage / (mass percentage of each chromatographic product and by-product) × 100%;

[0043] Relative crystallinity = sum of sample peak intensities / sum of standard sample peak intensities × 100% (the standard sample is the sample synthesized in Comparative Example 1).

[0044] [Example 1]

[0045] Mix 38.50g of 30% silica sol, 53.13g of anhydrous ethanol, and 11.48g of tetradecylamine, stir at room temperature, and add 173.08g of H₂O to achieve a molar ratio of SiO₂, tetradecylamine, ethanol, and H₂O of 1:0.3:6:50. Adjust the pH of the gel to 9.0 and continue stirring and aging at 20°C for 20 hours. The resulting gel is filtered, washed with deionized water, and dried at 120°C for 5 hours to obtain a precursor silicon material.

[0046] 1.65g of aluminum sulfate, 0.87g of dimethylamine, 1.41g of n-butylamine, and 0.77g of NaOH were added to the precursor silicon material, mixed thoroughly, and placed in the upper portion of a crystallization kettle. A certain amount of water was added to the bottom of the kettle, such that the molar ratio of SiO₂, Al₂O₃, (dimethylamine + n-butylamine), NaOH, and water in the mixture was 1:0.025:0.2:0.1:2. Crystallization was performed at 180°C for 120 hours to obtain an intermediate crystalline material. This intermediate crystalline material was filtered, washed with deionized water, dried, and calcined in a muffle furnace at 500°C for 5 hours to obtain a multi-level pore size (MFI) molecular sieve.

[0047] The XRD characterization results of the above molecular sieves are as follows Figure 1 As shown, the N2 physical adsorption characterization results are as follows Figure 2 As shown. Figure 1 It can be seen that the molecular sieve is a mesoporous MFI molecular sieve, and the calculated relative crystallinity is 74%. Figure 2 The hysteresis loop was observed, confirming the presence of mesopores. The pore volume with a pore size of less than 2.0 nm accounted for 30% of the total pore volume, the pore volume with a pore size of 2.0 to 5.0 nm accounted for 35% of the total pore volume, the pore volume with a pore size of 5.0 to 20.0 nm accounted for 27% of the total pore volume, and the pore volume with a pore size greater than 20.0 nm to 50.0 nm accounted for 8% of the total pore volume. The average pore diameter was 3.2 nm, and the total pore volume was 0.35 cm 3 / g, micropore volume is 0.26cm 3 / g, specific surface area is 524m 2 / g.

[0048] Application Example 1

[0049] 10 g of the multi-stage MFI molecular sieve prepared in Example 1 was placed in a reactor. 21.62 g of cyclopentene and 40 g of water were added, resulting in a cyclopentene:water molar ratio of 7:1. The reaction was stirred vigorously at a temperature of 130°C and a pressure of approximately 0.8 MPa. The reaction yielded a cyclopentene conversion of 8.3% and a cyclopentanol selectivity of 99.3%.

[0050] [Example 2]

[0051] Mix 38.50g of 30% silica sol, 70.84g of anhydrous ethanol, and 14.25g of dodecylamine, stir at room temperature, and add 50.25g of H₂O₂ to achieve a molar ratio of SiO₂, dodecylamine, ethanol, and H₂O of 1:0.4:8:80. Adjust the pH of the gel to 11.0 and continue stirring and aging at 15°C for 32 hours. The resulting gel is filtered, washed with deionized water, and dried at 120°C for 8 hours to obtain a precursor silicon material.

[0052] 1.03g of aluminum nitrate, 1.70g of trimethylamine, and 2.11g of n-butylamine were added to the precursor silicon material and mixed thoroughly. The mixture was then placed in the upper portion of a crystallization kettle. A certain amount of water was added to the bottom of the kettle to achieve a molar ratio of SiO₂, Al₂O₃, (trimethylamine + n-butylamine), NaOH, and water of 1:0.025:0.2:0.05:1. Crystallization was performed at 170°C for 144 hours to obtain an intermediate crystalline material. This intermediate crystalline material was filtered, washed with deionized water, dried, and calcined in a muffle furnace at 550°C for 5 hours to obtain a multi-level pore size (MFI) molecular sieve.

[0053] The XRD spectra of the above molecular sieves are Figure 1 Similar to the MFI molecular sieve containing mesopores, the relative crystallinity is calculated to be 68%. The N2 physical adsorption characterization results of this molecular sieve are similar to those of Figure 2 Similarly, hysteresis loops were observed, confirming the presence of mesopores. The pore volume with a pore size of less than 2.0 nm accounted for 37% of the total pore volume, the pore volume with a pore size of 2.0 to 5.0 nm accounted for 32% of the total pore volume, the pore volume with a pore size of 5.0 to 20.0 nm accounted for 21% of the total pore volume, and the pore volume with a pore size greater than 20.0 nm to 50.0 nm accounted for 10% of the total pore volume. The average pore diameter was 3.4 nm, and the total pore volume was 0.43 cm 3 / g, of which the micropore volume is 0.26cm 3 / g, specific surface area is 517m 2 / g.

[0054] Application Example 2

[0055] 10 g of the molecular sieve prepared in Example 2 was placed in a reactor. 21.62 g of cyclopentene and 40 g of water were added, resulting in a cyclopentene:water molar ratio of 7:1. The reaction was stirred vigorously at a temperature of 130°C and a pressure of approximately 0.8 MPa. The reaction yielded a cyclopentene conversion of 9.1% and a cyclopentanol selectivity of 99.5%.

[0056] [Example 3]

[0057] Mix 38.50g of 30% silica sol, 61.99g of anhydrous ethanol, and 20.50g of hexadecylamine, stir at room temperature, and add 146.30g of H₂O to achieve a molar ratio of SiO₂, hexadecylamine, ethanol, and H₂O of 1:0.5:7:50. Adjust the pH of the gel to 11.5 and continue stirring and aging at 23°C for 36 hours. The resulting gel is filtered, washed with deionized water, and dried at 120°C for 9 hours to obtain a precursor silicon material.

[0058] A mixture of 0.79g sodium aluminate, 2.81g diethylamine, 2.31g ethylenediamine, and 1.29g KOH was added to the precursor silicon material and mixed thoroughly. The mixture was then placed in the upper portion of a crystallization kettle. A certain amount of water was added to the bottom of the kettle to achieve a molar ratio of SiO₂, Al₂O₃, (diethylamine + ethylenediamine), KOH, and water of 1:0.05:0.4:0.12:4. Crystallization was performed at 175°C for 168 hours to obtain an intermediate crystalline material. This intermediate crystalline material was filtered, washed with deionized water, dried, and calcined in a muffle furnace at 480°C for 6 hours to obtain a multi-level pore MFI molecular sieve.

[0059] The XRD spectra of the above molecular sieves are Figure 1 Similarly, it is a mesoporous MFI molecular sieve with a calculated relative crystallinity of 66%. The N2 physical adsorption characterization results of this molecular sieve are similar to those of Figure 2 Similarly, hysteresis loops were observed, confirming the presence of mesopores. The pore volume with a pore size of less than 2.0 nm accounted for 28% of the total pore volume, the pore volume with a pore size of 2.0 to 5.0 nm accounted for 39% of the total pore volume, the pore volume with a pore size of 5.0 to 20.0 nm accounted for 24% of the total pore volume, and the pore volume with a pore size greater than 20.0 nm to 50.0 nm accounted for 9% of the total pore volume. The average pore diameter was 3.7 nm, and the total pore volume was 0.52 cm 3 / g, micropore volume is 0.27cm 3 / g, specific surface area of ​​553m 2 / g.

[0060] Application Example 3

[0061] 10 g of the MFI multi-level pore size molecular sieve prepared in Example 3 was placed in a reactor. 21.62 g of cyclopentene and 40 g of water were added, resulting in a cyclopentene:water molar ratio of 7:1. The reaction was stirred vigorously at a temperature of 130°C and a pressure of approximately 0.8 MPa. The reaction yielded a cyclopentene conversion of 10.1% and a cyclopentanol selectivity of 98.5%.

[0062] [Example 4]

[0063] Mix 11.55g of silica, 88.55g of anhydrous ethanol, and 8.74g of octadecylamine and stir at room temperature. Add 103.95g of H₂O to achieve a molar ratio of SiO₂, octadecylamine, ethanol, and H₂O of 1:0.2:10:30. Adjust the pH of the gel to 12.0 and continue stirring and aging at 35°C for 24 hours. Filter the resulting gel, wash with deionized water, and dry at 120°C for 7 hours to obtain a precursor silicon material.

[0064] 0.39g of aluminum oxide, 0.97g of triethylamine, 0.58g of ethylenediamine, and 0.77g of NaOH were added to the precursor silicon material and mixed thoroughly. The mixture was then placed in the upper portion of a crystallization kettle. A certain amount of water was added to the bottom of the kettle to achieve a molar ratio of SiO2, Al2O3, (triethylamine + ethylenediamine), NaOH, and water of 1:0.02:0.1:0.15:3.2. Crystallization was performed at 160°C for 150 hours to obtain an intermediate crystalline material. This intermediate crystalline material was filtered, washed with deionized water, dried, and calcined in a muffle furnace at 400°C for 10 hours to obtain a multi-level pore size (MFI) molecular sieve.

[0065] The XRD spectra of the above molecular sieves are Figure 1 Similar to the MFI molecular sieve containing mesopores, the relative crystallinity is calculated to be 78%. The N2 physical adsorption characterization results of this molecular sieve are similar to those of Figure 2 Similarly, hysteresis loops were observed, confirming the presence of mesopores. The pore volume with a pore size of less than 2.0 nm accounted for 41% of the total pore volume, the pore volume with a pore size of 2.0 to 5.0 nm accounted for 31% of the total pore volume, the pore volume with a pore size of 5.0 to 20.0 nm accounted for 18% of the total pore volume, and the pore volume with a pore size greater than 20.0 nm to 50.0 nm accounted for 10% of the total pore volume. The average pore diameter was 2.8 nm, and the total pore volume was 0.30 cm 3 / g, micropore volume is 0.15cm 3 / g, specific surface area is 503m 2 / g.

[0066] Application Example 4

[0067] 10g of the molecular sieve prepared in Example 4 was placed in a reactor. 21.62g of cyclopentene and 40g of water were added, resulting in a cyclopentene:water molar ratio of 7:1. Under vigorous stirring, the reaction temperature was 130°C and the reaction pressure was approximately 0.8 MPa. The reaction yielded a cyclopentene conversion of 8.6% and a cyclopentanol selectivity of 99.2%.

[0068] [Example 5]

[0069] Mix 11.55g of silica, 70.84g of anhydrous ethanol, and 3.83g of tetradecylamine and stir at room temperature. Add 46.5g of H₂O₃ to achieve a molar ratio of SiO₂, tetradecylamine, ethanol, and H₂O in the gel of 1:0.1:8:100. Adjust the pH of the gel to 8.0 and continue stirring and aging at 40°C for 12 hours. Filter the resulting gel, wash with deionized water, and dry at 120°C for 10 hours to obtain a precursor silicon material.

[0070] A mixture of 1.79g aluminum isopropoxide, 3.35g hexamethylenediamine, 2.11g n-butylamine, and 0.54g NaOH was added to the precursor silicon material and mixed thoroughly. The mixture was then placed in the upper portion of a crystallization kettle. A certain amount of water was added to the bottom of the kettle to achieve a molar ratio of SiO₂, Al₂O₃, (hexamethylenediamine + n-butylamine), NaOH, and water of 1:0.045:0.3:0.075:5. Crystallization was performed at 165°C for 128 hours to obtain an intermediate crystalline material. This intermediate crystalline material was filtered, washed with deionized water, dried, and calcined in a muffle furnace at 500°C for 5 hours to obtain a multi-level pore size (MFI) molecular sieve.

[0071] The XRD spectra of the above molecular sieves are Figure 1 Similarly, it is a mesoporous MFI molecular sieve with a calculated relative crystallinity of 65%. The N2 physical adsorption characterization results of this molecular sieve are similar to those of Figure 2 Similarly, hysteresis loops were observed, confirming the presence of mesopores. The pore volume with a pore size of less than 2.0 nm accounted for 19% of the total pore volume, the pore volume with a pore size of 2.0 to 5.0 nm accounted for 38% of the total pore volume, the pore volume with a pore size of 5.0 to 20.0 nm accounted for 29% of the total pore volume, and the pore volume with a pore size greater than 20.0 nm to 50.0 nm accounted for 14% of the total pore volume. The average pore diameter was 3.8 nm, and the total pore volume was 0.55 cm 3 / g micropore volume is 0.30cm 3 / g, with a specific surface area of ​​549m 2 / g.

[0072] Application Example 5

[0073] 10 g of the molecular sieve prepared in Example 5 was placed in a reactor. 21.62 g of cyclopentene and 40 g of water were added, resulting in a cyclopentene:water molar ratio of 7:1. The reaction was stirred vigorously at a temperature of 130°C and a pressure of approximately 0.8 MPa. The reaction yielded a cyclopentene conversion of 9.7% and a cyclopentanol selectivity of 99.0%.

[0074] [Example 6]

[0075] Mix 11.55g of silica, 26.57g of anhydrous ethanol, and 7.66g of tetradecylamine and stir at room temperature. Add 11.85g of H₂O₃ to achieve a molar ratio of SiO₂, tetradecylamine, ethanol, and H₂O in the gel of 1:0.2:3:90. Adjust the pH of the gel to 9.5 and continue stirring and aging at 17°C for 18 hours. Filter the resulting gel, wash with deionized water, and dry at 120°C for 6 hours to obtain a precursor silicon material.

[0076] A mixture of 0.95g sodium aluminate, 2.56g tetrapropylammonium bromide, 6.32g n-butylamine, and 0.86g KOH was added to the precursor silicon material, stirred thoroughly, and placed in the upper portion of a crystallization kettle. A certain amount of water was added to the bottom of the kettle to achieve a molar ratio of SiO₂, Al₂O₃, (tetrapropylammonium bromide + n-butylamine), KOH, and water of 1:0.06:0.5:0.08:4.5. Crystallization was performed at 170°C for 152 hours to obtain an intermediate crystalline material. This intermediate crystalline material was filtered, washed with deionized water, dried, and calcined in a muffle furnace at 500°C for 5 hours to obtain a multi-level pore size (MFI) molecular sieve.

[0077] The XRD spectra of the above molecular sieves are Figure 1 Similar to the MFI molecular sieve containing mesopores, the relative crystallinity is calculated to be 73%. The N2 physical adsorption characterization results of this molecular sieve are similar to those of Figure 2 Similarly, hysteresis loops were observed, confirming the presence of mesopores. The pore volume with a pore size of less than 2.0 nm accounted for 17% of the total pore volume, the pore volume with a pore size of 2.0 to 5.0 nm accounted for 40% of the total pore volume, the pore volume with a pore size of 5.0 to 20.0 nm accounted for 29% of the total pore volume, and the pore volume with a pore size greater than 20.0 nm to 50.0 nm accounted for 14% of the total pore volume. The average pore diameter was 3.0 nm, and the total pore volume was 0.38 cm 3 / g, micropore volume is 0.22cm 3 / g, specific surface area is 503m 2 / g.

[0078] Application Example 6

[0079] 10 g of the molecular sieve prepared in Example 6 was placed in a reactor. 21.62 g of cyclopentene and 40 g of water were added, resulting in a cyclopentene:water molar ratio of 7:1. Under vigorous stirring, the reaction temperature was 130°C and the reaction pressure was approximately 0.8 MPa. The reaction yielded a cyclopentene conversion of 8.0% and a cyclopentanol selectivity of 97.7%.

[0080] [Example 7]

[0081] Mix 11.55g of silica, 44.28g of anhydrous ethanol, and 10.68g of dodecylamine and stir at room temperature. Add 7.90g of H₂O₂ to achieve a molar ratio of SiO₂, dodecylamine, ethanol, and H₂O in the gel of 1:0.30:5:60. Adjust the pH of the gel to 10.5 and continue stirring and aging at 29°C for 28 hours. Filter the resulting gel, wash with deionized water, and dry at 120°C for 6 hours to obtain a precursor silicon material.

[0082] A mixture of 4.94g aluminum sulfate, 2.86g cyclohexylamine, and 1.08g NaOH was added to the precursor silicon material and mixed thoroughly. The mixture was then placed in the upper portion of a crystallization kettle. A certain amount of water was added to the bottom of the kettle to achieve a molar ratio of SiO₂, Al₂O₃, cyclohexylamine, NaOH, and water of 1:0.075:0.15:0.14:2.4. Crystallization was performed at 175°C for 155 hours to obtain an intermediate crystalline material. This intermediate crystalline material was filtered, washed with deionized water, dried, and calcined in a muffle furnace at 500°C for 5 hours to obtain a multi-level pore size (MFI) molecular sieve.

[0083] The XRD spectra of the above molecular sieves are Figure 1 Similarly, it is a mesoporous MFI molecular sieve with a calculated relative crystallinity of 65%. The N2 physical adsorption characterization results of this molecular sieve are similar to those of Figure 2 Similarly, hysteresis loops were observed, confirming the presence of mesopores. The pore volume with a pore size of less than 2.0 nm accounted for 41% of the total pore volume, the pore volume with a pore size of 2.0 to 5.0 nm accounted for 32% of the total pore volume, the pore volume with a pore size of 5.0 to 20.0 nm accounted for 18% of the total pore volume, and the pore volume with a pore size greater than 20.0 nm to 50.0 nm accounted for 9% of the total pore volume. The average pore diameter was 4.0 nm, and the total pore volume was 0.59 cm 3 / g, micropore volume is 0.30cm 3 / g, with a specific surface area of ​​536m 2 / g.

[0084] Application Example 7

[0085] 10 g of the molecular sieve prepared in Example 7 was placed in a reactor. 21.62 g of cyclopentene and 40 g of water were added, resulting in a cyclopentene:water molar ratio of 7:1. The reaction was stirred vigorously at a temperature of 130°C and a pressure of approximately 0.8 MPa. The reaction yielded a cyclopentene conversion of 9.4% and a cyclopentanol selectivity of 98.6%.

[0086] [Example 8]

[0087] Mix 40.04g of tetraethyl orthosilicate, 53.13g of anhydrous ethanol, and 10.68g of dodecylamine, stirring at room temperature. Add 42.55g of H₂O₂ to achieve a molar ratio of SiO₂, dodecylamine, ethanol, and H₂O in the gel of 1:0.3:6:70. Adjust the pH of the gel to 9.5 and continue stirring and aging at 32°C for 30 hours. Filter the resulting gel, wash with deionized water, and dry at 120°C for 7 hours to obtain a precursor silicon material.

[0088] A mixture of 3.97g kaolin, 0.55g isopropylamine, and 0.85g NaOH was added to the precursor silicon material and mixed thoroughly. The mixture was then placed in the upper portion of a crystallization kettle. A certain amount of water was added to the bottom of the kettle to achieve a molar ratio of SiO₂, Al₂O₃, isopropylamine, NaOH, and water of 1:0.08:0.05:0.11:3. Crystallization was performed at 180°C for 130 hours to obtain an intermediate crystalline material. This intermediate crystalline material was filtered, washed with deionized water, dried, and calcined in a muffle furnace at 500°C for 5 hours to obtain a multi-level pore size (MFI) molecular sieve.

[0089] The XRD spectra of the above molecular sieves are Figure 1 Similar to the MFI molecular sieve containing mesopores, the relative crystallinity is calculated to be 69%. The N2 physical adsorption characterization results of this molecular sieve are similar to those of Figure 2 Similarly, hysteresis loops were observed, confirming the presence of mesopores. The pore volume with a pore size of less than 2.0 nm accounted for 44% of the total pore volume, the pore volume with a pore size of 2.0 to 5.0 nm accounted for 28% of the total pore volume, the pore volume with a pore size of 5.0 to 20.0 nm accounted for 18% of the total pore volume, and the pore volume with a pore size greater than 20.0 nm to 50.0 nm accounted for 10% of the total pore volume. The average pore diameter was 3.5 nm, and the total pore volume was 0.53 cm 3 / g, micropore volume is 0.25cm 3 / g, specific surface area is 511m 2 / g.

[0090] Application Example 8

[0091] 10 g of the molecular sieve prepared in Example 8 was placed in a reactor. 21.62 g of cyclopentene and 40 g of water were added, resulting in a cyclopentene:water molar ratio of 7:1. The reaction was stirred vigorously at a temperature of 130°C and a pressure of approximately 0.8 MPa. The reaction yielded a cyclopentene conversion of 9.0% and a cyclopentanol selectivity of 98.8%.

[0092] [Example 9]

[0093] Mix 40.04g of tetraethyl orthosilicate, 53.13g of anhydrous ethanol, and 20.50g of hexadecylamine and stir at room temperature. Add 42.55g of H₂O₂ to achieve a molar ratio of SiO₂, hexadecylamine, ethanol, and H₂O in the gel of 1:0.5:6:70. Adjust the pH of the gel to 8.5 and continue stirring and aging at 18°C ​​for 24 hours. Filter the resulting gel, wash with deionized water, and dry at 120°C for 9 hours to obtain a precursor silicon material.

[0094] A mixture of 10.68g of montmorillonite, 1.79g of tetrapropylammonium bromide, 2.73g of trimethylamine, and 0.69g of NaOH was added to the precursor silicon material and mixed thoroughly. The mixture was then placed in the upper portion of a crystallization kettle. A certain amount of water was added to the bottom of the kettle to achieve a molar ratio of SiO₂, Al₂O₃, (trimethylamine + tetrapropylammonium bromide), NaOH, and water of 1:0.09:0.35:0.09:2.5. Crystallization was performed at 180°C for 138 hours to obtain an intermediate crystalline material. This intermediate crystalline material was filtered, washed with deionized water, dried, and calcined in a muffle furnace at 500°C for 5 hours to obtain a multi-level pore MFI molecular sieve.

[0095] The XRD spectra of the above molecular sieves are Figure 1 Similar to the MFI molecular sieve containing mesopores, the relative crystallinity is calculated to be 70%. The N2 physical adsorption characterization results of this molecular sieve are similar to those of Figure 2 Similarly, hysteresis loops were observed, confirming the presence of mesopores. The pore volume with a pore size of less than 2.0 nm accounted for 37% of the total pore volume, the pore volume with a pore size of 2.0 to 5.0 nm accounted for 32% of the total pore volume, the pore volume with a pore size of 5.0 to 20.0 nm accounted for 20% of the total pore volume, and the pore volume with a pore size greater than 20.0 nm to 50.0 nm accounted for 11% of the total pore volume. The average pore diameter was 3.0 nm, and the total pore volume was 0.46 cm 3 / g, micropore volume is 0.23cm 3 / g, specific surface area is 516m 2 / g.

[0096] Application Example 9

[0097] 10 g of the molecular sieve prepared in Example 9 was placed in a reactor. 21.62 g of cyclopentene and 40 g of water were added, resulting in a cyclopentene:water molar ratio of 7:1. The reaction was stirred vigorously at a temperature of 130°C and a pressure of approximately 0.8 MPa. The reaction yielded a cyclopentene conversion of 9.1% and a cyclopentanol selectivity of 98.5%.

[0098] [Example 10]

[0099] Mix 40.04g of tetraethyl orthosilicate, 35.42g of anhydrous ethanol, and 12.30g of hexadecylamine and stir at room temperature. Add 69.30g of H₂O to achieve a molar ratio of SiO₂, hexadecylamine, ethanol, and H₂O of 1:0.3:4:20 in the gel. Adjust the pH of the gel to 11.0 and continue stirring and aging at 30°C for 20 hours. Filter the resulting gel, wash with deionized water, and dry at 120°C for 8 hours to obtain a precursor silicon material.

[0100] A mixture of 1.96g alumina, 2.60g ethylenediamine, 2.47g isopropylamine, and 1.16g NaOH was added to the precursor silicon material and mixed thoroughly. The mixture was then placed in the upper portion of a crystallization kettle. A certain amount of water was added to the bottom of the kettle to achieve a molar ratio of SiO₂, Al₂O₃, (ethylenediamine + isopropylamine), NaOH, and water of 1:0.1:0.45:0.15:3.5. Crystallization was performed at 170°C for 140 hours to obtain an intermediate crystalline material. This intermediate crystalline material was filtered, washed with deionized water, dried, and calcined in a muffle furnace at 500°C for 5 hours to obtain a multi-level pore MFI molecular sieve.

[0101] The XRD spectra of the above molecular sieves are Figure 1 Similar to the MFI molecular sieve containing mesopores, the relative crystallinity is calculated to be 64%. The N2 physical adsorption characterization results of this molecular sieve are similar to those of Figure 2 Similarly, hysteresis loops were observed, confirming the presence of mesopores. The pore volume with a pore size of less than 2.0 nm accounted for 33% of the total pore volume, the pore volume with a pore size of 2.0 to 5.0 nm accounted for 39% of the total pore volume, the pore volume with a pore size of 5.0 to 20.0 nm accounted for 16% of the total pore volume, and the pore volume with a pore size greater than 20.0 nm to 50.0 nm accounted for 12% of the total pore volume. The average pore diameter was 3.1 nm, and the total pore volume was 0.52 cm 3 / g, micropore volume is 0.20cm 3 / g, specific surface area of ​​537m 2 / g.

[0102] Application Example 10

[0103] 10 g of the molecular sieve prepared in Example 10 was placed in a reactor. 21.62 g of cyclopentene and 40 g of water were added, resulting in a cyclopentene:water molar ratio of 7:1. The reaction was stirred vigorously at a temperature of 130°C and a pressure of approximately 0.8 MPa. The reaction yielded a cyclopentene conversion of 9.5% and a cyclopentanol selectivity of 98.9%.

[0104] [Comparative Example 1]

[0105] 38.50g of 30% silica sol, 1.65g of aluminum sulfate, 0.87g of dimethylamine, 1.41g of n-butylamine, and 0.77g of NaOH were stirred evenly and placed in the upper portion of a crystallization kettle. Water was added to the bottom of the kettle to achieve a molar ratio of SiO₂, Al₂O₃, (dimethylamine + n-butylamine), NaOH, and water of 1:0.025:0.2:0.1:2. Crystallization was performed at 180°C for 120 hours to obtain a raw molecular sieve powder. The raw powder was then washed, filtered, rinsed with deionized water, dried, and calcined in a muffle furnace at 500°C for 5 hours to obtain an MFI molecular sieve.

[0106] Similarly to the test method of the above embodiment, no hysteresis loop was observed. It was found that the pore volume with a pore diameter of less than 2.0 nm accounted for 69% of the total pore volume, the pore volume with a pore diameter of 2.0 to 5.0 nm accounted for 18% of the total pore volume, the pore volume with a pore diameter of 5.0 to 20.0 nm accounted for 10% of the total pore volume, and the pore volume with a pore diameter greater than 20.0 nm to 50.0 nm accounted for 3% of the total pore volume. The average pore diameter of the molecular sieve was 1.95 nm, and the total pore volume was 0.17 cm 3 / g, micropore volume is 0.10cm 3 / g. The specific surface area of ​​the molecular sieve was measured to be 269m 2 / g.

[0107] 10g of the MFI multi-level pore size molecular sieve prepared in Comparative Example 1 was placed in a reactor. 21.62g of cyclopentene and 40g of water were added, resulting in a cyclopentene:water molar ratio of 7:1. Under vigorous stirring, the reaction temperature was 130°C and the reaction pressure was approximately 0.8 MPa. The reaction yielded a cyclopentene conversion of 3.7% and a cyclopentanol selectivity of 90.5%.

[0108] [Comparative Example 2]

[0109] 38.50 g of 30% silica sol and 173.08 g of H₂O were added to achieve a molar ratio of SiO₂ to H₂O of 1:50. The pH of the gel was adjusted to 9.0 and the mixture was stirred and aged at 20°C for 20 hours. The resulting gel was filtered, washed with deionized water, and dried at 120°C for 5 hours to obtain a precursor silicon material.

[0110] 1.65g of aluminum sulfate, 0.87g of dimethylamine, 1.41g of n-butylamine, and 0.77g of NaOH were added to the precursor silicon material and mixed thoroughly. The mixture was then placed in the upper portion of a crystallization kettle. A certain amount of water was added to the bottom of the kettle to achieve a molar ratio of SiO2, Al2O3, (dimethylamine + n-butylamine), NaOH, and water of 1:0.025:0.2:0.1:2. Crystallization was performed at 180°C for 120 hours to obtain an intermediate crystalline material. This intermediate crystalline material was filtered, washed with deionized water, dried, and calcined in a muffle furnace at 500°C for 5 hours to obtain a molecular sieve.

[0111] The molecular sieve was tested and found to have no hysteresis loop. The pore volume with a pore diameter of less than 2.0 nm accounted for 67% of the total pore volume, the pore volume with a pore diameter of 2.0 to 5.0 nm accounted for 17% of the total pore volume, the pore volume with a pore diameter of 5.0 to 20.0 nm accounted for 13% of the total pore volume, and the pore volume with a pore diameter greater than 20.0 nm to 50.0 nm accounted for 3% of the total pore volume. The molecular sieve synthesized by this method was found to have an average pore diameter of 2.3 nm and a total pore volume of 0.21 cm 3 / g, micropore volume is 0.15cm 3 / g. The specific surface area of ​​the molecular sieve was measured to be 321m 2 / g.

[0112] 10g of the molecular sieve prepared in Comparative Example 2 was placed in a reactor. 21.62g of cyclopentene and 40g of water were added, resulting in a cyclopentene:water molar ratio of 7:1. Under vigorous stirring, the reaction temperature was 130°C and the reaction pressure was approximately 0.8 MPa. The reaction yielded a cyclopentene conversion of 4.0% and a cyclopentanol selectivity of 89.2%.

[0113] [Comparative Example 3]

[0114] Mix 38.50g of 30% silica sol, 53.13g of anhydrous ethanol, and 7.45g of n-octylamine, stir at room temperature, and add 173.08g of H₂O to achieve a molar ratio of SiO₂, n-octylamine, ethanol, and H₂O of 1:0.3:6:50. Adjust the pH of the gel to 9.0 and continue stirring and aging at 20°C for 20 hours. The resulting gel is filtered, washed with deionized water, and dried at 120°C for 5 hours to obtain a precursor silicon material.

[0115] 1.65g of aluminum sulfate, 0.87g of dimethylamine, 1.41g of n-butylamine, and 0.77g of NaOH were added to the precursor silicon material and mixed thoroughly. The mixture was then placed in the upper portion of a crystallization kettle. A certain amount of water was added to the bottom of the kettle to achieve a molar ratio of SiO2, Al2O3, (dimethylamine + n-butylamine), NaOH, and water of 1:0.025:0.2:0.1:2. Crystallization was performed at 180°C for 120 hours to obtain an intermediate crystalline material. This intermediate crystalline material was filtered, washed with deionized water, dried, and calcined in a muffle furnace at 500°C for 5 hours to obtain a molecular sieve.

[0116] The sample was measured and no hysteresis loop was observed. The pore volume with a pore diameter of less than 2.0 nm accounted for 73% of the total pore volume, the pore volume with a pore diameter of 2.0 to 5.0 nm accounted for 17% of the total pore volume, the pore volume with a pore diameter of 5.0 to 20.0 nm accounted for 8% of the total pore volume, and the pore volume with a pore diameter greater than 20.0 nm to 50.0 nm accounted for 2% of the total pore volume. The molecular sieve synthesized by this method was measured to have an average pore diameter of 2.2 nm and a total pore volume of 0.21 cm 3 / g, micropore volume is 0.12cm 3 / g. The specific surface area of ​​the molecular sieve was measured to be 276m 2 / g.

[0117] 10g of the porous molecular sieve prepared in Comparative Example 3 was placed in a reactor. 21.62g of cyclopentene and 40g of water were added, resulting in a cyclopentene:water molar ratio of 7:1. Under vigorous stirring, the reaction temperature was 130°C and the reaction pressure was approximately 0.8 MPa. The reaction resulted in a cyclopentene conversion of 3.7% and a cyclopentanol selectivity of 89.0%.

[0118] [Comparative Example 4]

[0119] Mix 38.50g of 30% silica sol, 53.13g of anhydrous ethanol, and 11.48g of tetradecylamine, stir at room temperature, and add 173.08g of H₂O to achieve a molar ratio of SiO₂, tetradecylamine, ethanol, and H₂O of 1:0.3:6:50. Adjust the pH of the gel to 9.0 and continue stirring and aging at 20°C for 20 hours. The resulting gel is filtered, washed with deionized water, and dried at 120°C for 5 hours to obtain a precursor silicon material.

[0120] 1.65g of aluminum sulfate, 0.87g of dimethylamine, 2.27g of n-propylamine, and 0.77g of NaOH were added to the precursor silicon material and mixed thoroughly. The mixture was then placed in the upper portion of a crystallization kettle. A certain amount of water was added to the bottom of the kettle to achieve a molar ratio of SiO2, Al2O3, (dimethylamine + n-butylamine), NaOH, and water of 1:0.025:0.2:0.1:2. Crystallization was performed at 180°C for 120 hours to obtain an intermediate crystalline material. This intermediate crystalline material was filtered, washed with deionized water, dried, and calcined in a muffle furnace at 500°C for 5 hours to obtain an aluminum-containing MFI molecular sieve.

[0121] The sample was measured and no hysteresis loop was observed. The pore volume with a pore diameter of less than 2.0 nm accounted for 70% of the total pore volume, the pore volume with a pore diameter of 2.0 to 5.0 nm accounted for 16% of the total pore volume, the pore volume with a pore diameter of 5.0 to 20.0 nm accounted for 11% of the total pore volume, and the pore volume with a pore diameter greater than 20.0 nm to 50.0 nm accounted for 3% of the total pore volume. The molecular sieve synthesized by this method was measured to have an average pore diameter of 2.7 nm and a total pore volume of 0.25 cm 3 / g, of which the micropore volume is 0.14cm 3 / g. The specific surface area of ​​the molecular sieve was measured to be 269m 2 / g.

[0122] 10g of the molecular sieve prepared in Comparative Example 4 was placed in a reactor. 21.62g of cyclopentene and 40g of water were added, resulting in a cyclopentene:water molar ratio of 7:1. Under vigorous stirring, the reaction temperature was 130°C and the reaction pressure was approximately 0.8 MPa. The reaction yielded a cyclopentene conversion of 3.2% and a cyclopentanol selectivity of 90.2%.

[0123] [Comparative Examples 5-7]

[0124] Compared with the above Example 1 and Application Example 1, the difference is that only the crystallization time of the multi-level pore MFI molecular sieve prepared in Comparative Examples 5-7 was changed. The corresponding characterization results are shown in Table 1:

[0125] Table 1

[0126] Comparative Example 5 6 7 Crystallization time (hours) 8 16 175 Cyclopentene conversion rate % 3.4 3.2 2.8 Cyclopentanol selectivity% 86.1 83.5 87.0 Is there a hysteresis loop? none none none Average pore diameter (nm) 2.5 2.2 2.8 <![CDATA[Total pore volume (cm 3 / g)]]> 0.23 0.21 0.25 <![CDATA[Micropore volume (cm 3 / g)]]> 0.15 0.17 0.21 <![CDATA[BET specific surface area (m 2 / g)]]> 265 231 287 Pore ​​diameter less than 2.0nm accounts for % of total pore volume 72 75 80 Pore ​​diameter 2.0~5.0nm accounts for % of total pore volume 18 14 12 Pore ​​diameter 5.0~20.0nm accounts for % of total pore volume 7 9 6 % of total pore volume between 20.0nm and 50.0nm 3 2 2

[0127] [Comparative Examples 8-10]

[0128] Compared with the above Example 1 and Application Example 1, the difference is that only the calcination temperature of the multi-level pore MFI molecular sieve prepared in Comparative Examples 8-10 was changed. The corresponding characterization results are shown in Table 2:

[0129] Table 2

[0130]

[0131]

[0132] The embodiments described herein are merely detailed descriptions of the technical solutions of the present invention. However, the present invention is not limited to these embodiments. That is, the present invention is not dependent on the steps described in these embodiments for implementation. In summary, any improvements made by those skilled in the art to the present invention, including replacements of the raw materials and additives described herein, selection of specific implementation methods, etc., fall within the scope of protection and disclosure of the present invention.

Claims

1. A multi-stage pore MFI molecular sieve, characterized in that: The multi-level pores include micropores and mesopores, and the specific surface area of ​​the molecular sieve is 500-600m 2 / g, with a total pore volume of 0.30~0.60cm 3 / g, micropore volume is 0.15~0.30cm 3 / g; the pore distribution of the molecular sieve is as follows: the pore volume with a pore diameter of less than 2.0 nm accounts for 15% to 45% of the total pore volume, the pore volume with a pore diameter of 2.0 to 5.0 nm accounts for 20% to 40% of the total pore volume, the pore volume with a pore diameter of 5.0 to 20.0 nm accounts for 15% to 30% of the total pore volume, and the pore volume with a pore diameter greater than 20.0 nm to 50.0 nm accounts for less than 15% of the total pore volume; the micropores refer to pores with a pore diameter of 0.5 to 0.8 nm, and the mesopores refer to pores with a pore diameter of 2.0 to 50.0 nm.

2. The molecular sieve according to claim 1, characterized in that The average pore size of the molecular sieve is 2.8-4.0 nm.

3. The molecular sieve according to claim 1 or 2, characterized in that For the molecular sieve, the volume of pores with a pore diameter greater than 20.0 nm to 50.0 nm accounts for 8% to 14% of the total pore volume.

4. The method for preparing the multi-stage pore MFI molecular sieve according to any one of claims 1 to 3, comprising the following steps: (1) mixing a silicon source, a first template, anhydrous ethanol, and water to obtain a gel, adjusting the pH value of the gel to 8-12, and aging the gel to obtain a precursor material; (2) The precursor material obtained in step (1), the aluminum source, the second template, and the alkali source are mixed and placed on the top of a crystallization kettle, and a certain amount of water is added to the bottom of the crystallization kettle for crystallization to obtain an intermediate crystalline material; (3) calcining the intermediate crystalline material obtained in step (2) to obtain the multi-level pore MFI molecular sieve.

5. The preparation method according to claim 4, characterized in that In step (1), the molar ratio of the silicon source (calculated as SiO2), the first template, anhydrous ethanol and H2O is 1: (0.1-0.5): (3-10): (20-100); And / or, in step (2), the precursor material is calculated as SiO2, the aluminum source is calculated as Al2O3, the second template, the alkali source is calculated as OH - The molar ratio of iodine and water is 1: (0.02-0.1): (0.05-0.5): (0.05-0.15): (1-5).

6. The preparation method according to claim 4 or 5, characterized in that The silicon source is selected from at least one of silica sol, solid silicon oxide, white carbon black or silicate; the first template is selected from at least one of dodecylamine, tetradecylamine, hexadecylamine or octadecylamine; the aluminum source is selected from at least one of aluminum hydroxide, sodium aluminate, aluminum isopropoxide, aluminum nitrate, aluminum sulfate, kaolin or montmorillonite; the alkali source is selected from at least one of alkali metal hydroxides; and the second template is selected from at least one of tetrapropylammonium bromide, dimethylamine, trimethylamine, ethylenediamine, hexamethylenediamine, cyclohexylamine, isopropylamine, diethylamine, triethylamine or n-butylamine.

7. The preparation method according to claim 4, characterized in that The aging temperature in step (1) is 10-40°C and the aging time is 12-36 hours; And / or, the calcination conditions in step (3) are as follows: the calcination temperature is 400-550° C., the calcination time is 5-10 hours, and the atmosphere is an oxygen-containing gas.

8. The preparation method according to claim 4, characterized in that The crystallization conditions in step (2) are as follows: the crystallization temperature is 130-200° C., and the crystallization time is 1-14 days.

9. The preparation method according to claim 4, characterized in that The crystallization conditions in step (2) are as follows: the crystallization temperature is 150-190° C., and the crystallization time is 5-7 days.

10. Use of the multi-level pore MFI molecular sieve according to any one of claims 1 to 3, or the multi-level pore MFI molecular sieve prepared according to the preparation method according to any one of claims 4 to 9, in one or more of olefin hydration, aromatics alkylation, catalytic cracking of C4 and above alkanes or alkenes, aromatization, and toluene disproportionation reactions.

11. The use according to claim 10, characterized in that The application is olefin hydration reaction.

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