A multi-level pore titanium silicon molecular sieve and its preparation method and application

Abstract

The present invention discloses a multi-level pore titanium silicate molecular sieve, its preparation method, and application. The multi-level pores in the molecular sieve include micropores and mesopores, and the pore distribution 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 45% of the total pore volume, the volume of pores with a pore diameter of 5.0 to 20.0 nm accounts for 10% to 40% 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. The titanium silicate molecular sieve of the present invention is used in the oxidation reaction of hydrogen peroxide to remove trace sulfur-containing organic matter from refined naphthalene, and exhibits high activity, good stability, and excellent selectivity.

Description

Technical Field

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

[0002] Titanium silicate TS-1 is a titanium silicate with an MFI structure. In the presence of H2O2, it can be used as a catalyst for the selective oxidation of a range of organic compounds, such as olefin epoxidation, cyclohexanone ammoxidation, and phenol hydroxylation. These reactions all feature mild conditions, relatively simple processes, and environmentally friendly properties, meeting the catalyst requirements for atom-economic reactions and green chemistry. While the TS-1 molecular sieve catalyst offers many advantages, its MFI structure has relatively narrow pores. In applications such as catalyzing the oxidation of large sulfur-containing organic compounds to sulfones or sulfoxides, these pores are easily clogged, leading to catalyst deactivation.

[0003] Titanium silicate molecular sieve TS-1 is mainly synthesized by hydrothermal method. The most classic method is to add a template agent, such as tetrapropylammonium hydroxide, to the silicon source, then dropwise add a titanium source such as tetraethyl titanate, mix and stir for a period of time, remove alcohol at 80-90℃, add water, and then stir and crystallize at 170℃ for 10 days. Another method is to first hydrolyze tetraethyl titanate, then cool to 5℃, add H2O2 and stir at 5℃ for 2 hours until the solution is clear, then add tetrapropylammonium hydroxide and silicon source, mix and age overnight, heat and stir at 80-90℃ for 6 hours to remove alcohol, and crystallize at 170℃ in a crystallization kettle.

[0004] After improvements, tetrabutyl titanate was used instead of tetraethyl titanate to improve the matching degree of silicate and titanate hydrolysis rates, thereby reducing the content of non-framework titanium; tetrapropylammonium bromide was used to partially or completely replace tetrapropylammonium hydroxide, which can reduce the amount of expensive organic amine templates; inorganic silicon and inorganic titanium were used instead of organic silicon and titanate, respectively, to expand and enrich the sources of raw materials for TS-1 molecular sieve synthesis, thereby further reducing costs. In addition, the crystallization time was also correspondingly shortened to less than 3 days. The titanium silicalite molecular sieve TS-1 synthesized by the above method has a small specific surface area and contains only micropores and intercrystalline macropores, without mesoporous channels.

[0005] Naphthalene is an important organic chemical raw material, widely used in the production of phthalic anhydride, 2,6-naphthalenedioic acid, naphthol, and other products. Refined naphthalene is generally used in industrial reactions requiring high purity. However, refined naphthalene still contains approximately 1000 mg / kg of sulfur-containing organic compounds, primarily benzothiophene. Due to the close proximity of physical properties such as boiling points, conventional methods such as hydrogenation and adsorption are difficult to remove. Summary of the Invention

[0006] The present invention aims to address the shortcomings of the prior art by providing a multi-level pore titanium silicate molecular sieve, a preparation method thereof, and its application. The titanium silicate molecular sieve prepared by the present invention exhibits high activity, good selectivity, and low by-products when used in the reaction of removing trace sulfur-containing organic matter from refined naphthalene using hydrogen peroxide oxidation.

[0007] The first aspect of the present invention provides a multi-level pore titanium silicalite molecular sieve, wherein the multi-level pores include: micropores and mesopores, and the pore distribution of the multi-level pore titanium silicalite 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 45% of the total pore volume, the volume of pores with a pore diameter of 5.0 to 20.0 nm accounts for 10% to 40% of the total pore volume, preferably 20% to 40%, 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 2% to 15%.

[0008] 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 to 50 nm.

[0009] Furthermore, the average pore size of the multi-level pore titanium silicate molecular sieve is 2.8 to 4.5 nm.

[0010] Furthermore, the specific surface area of ​​the molecular sieve is 500 to 600 m 2 / g, total pore volume of 0.30~0.60cm 3 / g, and the mesopore volume is 0.12~0.25cm 3 / g, micropore volume is 0.18~0.45cm 3 / g.

[0011] Furthermore, the relative crystallinity of the molecular sieve is 60% to 75%.

[0012] The second aspect of the present invention provides a method for preparing the multi-level pore titanium silicalite molecular sieve, comprising the following steps:

[0013] (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;

[0014] (2) mixing the precursor material obtained in step (1), the titanium source, and the second template and placing them on the top of a crystallization kettle, adding water to the bottom of the crystallization kettle, and crystallizing to obtain an intermediate crystalline material;

[0015] (3) calcining the intermediate crystalline material obtained in step (2) to obtain the multi-level pore titanium silicon molecular sieve.

[0016] 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).

[0017] Furthermore, in step (1), the silicon source is selected from at least one of silica sol, solid silicon oxide, white carbon black or silicate.

[0018] Furthermore, in step (1), the first template is selected from at least one of dodecylamine, tetradecylamine, hexadecylamine or octadecylamine.

[0019] Furthermore, in step (1), the aging temperature is 10 to 40° C., and the aging time is 12 to 36 hours.

[0020] Furthermore, in step (1), the pH can be adjusted by adding ammonia water.

[0021] 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.

[0022] Furthermore, in step (2), the molar ratio of the precursor material calculated as SiO2, the titanium source calculated as TiO2, the second template and water is 1: (0.02-0.1): (0.05-0.5): (1-5).

[0023] Furthermore, in step (2), the titanium source is selected from at least one of tetraalkyl titanate or titanium halide.

[0024] 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.

[0025] Furthermore, in step (2), the crystallization conditions are as follows: the crystallization temperature is 130-200° C., and the crystallization time is 48-240 hours. Preferably, the crystallization temperature is 160-180° C., and the crystallization time is 80-120 hours.

[0026] 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.

[0027] 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).

[0028] The third aspect of the present invention provides an application of the multi-level pore titanium silicalite molecular sieve.

[0029] Furthermore, the application is the application in the selective oxidation reaction of organic matter with the participation of H2O2.

[0030] Furthermore, the selective oxidation reaction of organic matter with the participation of H2O2 is one or more of the oxidation of sulfur-containing organic compounds to sulfones or sulfoxides, olefin epoxidation, cyclohexanone ammoxidation and phenol hydroxylation; preferably, the selective oxidation reaction of organic matter with the participation of H2O2 is the oxidation of sulfur-containing organic compounds to sulfones or sulfoxides.

[0031] Furthermore, a quantity of the prepared multi-level porous titanium silicalite is added to a tank reactor, and H2O2, anhydrous methanol, and refined naphthalene are added in sequence, and reacted at 40-100°C with stirring for 3-10 hours. The sulfur content of the refined naphthalene before the reaction is 1000-1500 mg / kg.

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

[0033] The titanium silicalite 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 selective oxidation reactions of organic matter in the presence of H2O2, especially the oxidation of sulfur-containing organic compounds to sulfones or sulfoxides. In such reactions, it has the characteristics of high activity, good selectivity and few by-products.

[0034] The preparation method of the 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 a titanium source, and undergoes dry gel conversion under the action of water vapor. The method utilizes the fact that the microporous small molecule organic amine template has a weak guiding ability during the crystallization process of the molecular sieve, so that the mesoporous precursor is converted into a monolithic TS-1 molecular sieve in situ. The titanium silicon 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. The above-mentioned specific structural characteristics make the molecular sieve have the advantages of good catalytic activity, faster material diffusion rate, more stable catalyst performance, and fewer by-products in the reaction of removing trace sulfur-containing organic matter from refined naphthalene by oxidation with hydrogen peroxide. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is the XRD spectrum of the multi-level pore titanium silicate molecular sieve prepared in Example 1 of the present invention;

[0036] Figure 2 This is the N2 adsorption-desorption curve of the multi-level pore titanium silicalite prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0037] 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.

[0038] The present invention uses the following equipment to characterize the prepared multi-level pore titanium silicate molecular sieve, and the following examples all use the same characterization equipment and testing methods.

[0039] 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.

[0040] 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.

[0041] In the present invention, the total sulfur and total nitrogen contents of organic matter are determined using an ANTEK / MODEL 735 gas phase sulfur and nitrogen content analyzer produced by PAC Corporation of the United States.

[0042] The calculation formula of the conversion rate in the application example of the present invention is as follows:

[0043] Removal rate of trace sulfur from refined naphthalene X s =(total sulfur content before oxidative desulfurization of refined naphthalene - total sulfur content after oxidative desulfurization of refined naphthalene) / total sulfur content before oxidative desulfurization of refined naphthalene × 100%, sulfur content is measured in mass fraction;

[0044] 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).

[0045] [Example 1]

[0046] 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.

[0047] 1.63g of tetrabutyl titanate, 0.30g of dimethylamine, and 0.49g 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, TiO2, (dimethylamine + n-butylamine), and water of 1:0.025:0.07:2. Crystallization was performed at 180°C for 82 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 hierarchical titanium silicon molecular sieve.

[0048] 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 has an MFI topological structure and the calculated relative crystallinity is 62%. 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 25% of the total pore volume, the pore volume with a pore size of 2.0-5.0 nm accounted for 31% of the total pore volume, the pore volume with a pore size of 5.0-20.0 nm accounted for 32% 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 3.0 nm, and the total pore volume was 0.45 cm 3 / g, micropore volume is 0.31cm 3 / g, specific surface area is 511m 2 / g.

[0049] Application Example 1

[0050] 1 g of the multi-level porous titanium silicalite prepared in Example 1 was added to a kettle reactor, and 10 ml of 30% H2O2, 40 ml of methanol and 10 g of refined naphthalene (sulfur content of 1150 mg / kg) were added in sequence, and the mixture was reacted at 70°C under stirring for 6 hours.

[0051] The reaction product was sampled and analyzed using a gas phase sulfur and nitrogen analyzer. The reaction results showed that the oxidation removal rate of trace sulfur in refined naphthalene was 99.5%.

[0052] [Example 2]

[0053] 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.

[0054] 2.61g of tetrabutyl titanate, 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, TiO2, (trimethylamine + n-butylamine), and water of 1:0.04:0.3:1. Crystallization was performed at 170°C for 96 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 hierarchical titanium silicon molecular sieve.

[0055] The XRD spectra of the above molecular sieves are Figure 1Similar to the titanium silicalite containing mesoporous, it has an MFI topological structure and a calculated relative crystallinity of 71%. The N2 physical adsorption characterization results of the 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 40% of the total pore volume, the pore volume with a pore size of 2.0 to 5.0 nm accounted for 37% 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 2% of the total pore volume. The average pore diameter was 3.9 nm, and the total pore volume was 0.51 cm 3 / g, of which the micropore volume is 0.30cm 3 / g, specific surface area is 521m 2 / g.

[0056] Application Example 2

[0057] 1 g of the molecular sieve prepared in Example 2 was added to a tank reactor, and 10 ml of 30% H2O2, 40 ml of methanol and 10 g of refined naphthalene (sulfur content of 1150 mg / kg) were added in sequence. The mixture was stirred at 70°C for 6 hours.

[0058] The reaction product was sampled and analyzed using a gas phase sulfur and nitrogen analyzer. The reaction results showed that the oxidation removal rate of trace sulfur in refined naphthalene was 99.7%.

[0059] [Example 3]

[0060] 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.

[0061] A mixture of 3.92g of tetrabutyl titanate, 1.41g of diethylamine, and 1.16g of ethylenediamine 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, TiO2, (diethylamine + ethylenediamine), and water of 1:0.06:0.2:4.0. Crystallization was performed at 175°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 480°C for 6 hours to obtain a hierarchical titanium silicon molecular sieve.

[0062] The XRD spectra of the above molecular sieves are Figure 1Similar to the titanium silicalite containing mesopores, it has an MFI topological structure and a calculated relative crystallinity of 64%. The N2 physical adsorption characterization results of the 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 35% 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 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 6% of the total pore volume. The average pore diameter was 3.7 nm, and the total pore volume was 0.55 cm 3 / g, micropore volume is 0.36cm 3 / g, specific surface area is 518m 2 / g.

[0063] Application Example 3

[0064] 1 g of the molecular sieve prepared in Example 3 was added to a tank reactor, and 10 ml of 30% H2O2, 40 ml of methanol and 10 g of refined naphthalene (sulfur content: 1150 mg / kg) were added in sequence. The mixture was stirred at 70°C for 6 hours.

[0065] The reaction product was sampled and analyzed using a gas phase sulfur and nitrogen analyzer. The reaction results showed that the oxidation removal rate of trace sulfur in refined naphthalene was 99.4%.

[0066] [Example 4]

[0067] 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.

[0068] 1.31g of tetrabutyl titanate, 0.97g of triethylamine, and 0.58g of ethylenediamine 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 crystallization kettle to achieve a molar ratio of SiO2, TiO2, (triethylamine + ethylenediamine), and water of 1:0.02:0.1:3.2. Crystallization was performed at 160°C for 100 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 hierarchical titanium silicon molecular sieve.

[0069] The XRD spectra of the above molecular sieves are Figure 1Similar to the titanium silicalite molecular sieve containing mesopores, it has an MFI topological structure and a calculated relative crystallinity of 70%. The N2 physical adsorption characterization results of the 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 42% of the total pore volume, the pore volume with a pore size of 5.0 to 20.0 nm accounted for 26% of the total pore volume, and the pore volume with a pore size greater than 20.0 nm to 50.0 nm accounted for 4% of the total pore volume. The average pore diameter was 2.9 nm, and the total pore volume was 0.33 cm 3 / g, micropore volume is 0.28cm 3 / g, specific surface area is 509m 2 / g.

[0070] Application Example 4

[0071] 1 g of the molecular sieve prepared in Example 4 was added to a tank reactor, and 10 ml of 30% H2O2, 40 ml of methanol and 10 g of refined naphthalene (sulfur content of 1150 mg / kg) were added in sequence. The mixture was stirred at 70°C for 6 hours.

[0072] The reaction product was sampled and analyzed using a gas phase sulfur and nitrogen analyzer. The reaction results showed that the oxidation removal rate of trace sulfur in refined naphthalene was 99.8%.

[0073] [Example 5]

[0074] 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.

[0075] A mixture of 2.15g of tetrabutyl titanate, 4.47g of hexamethylenediamine, and 1.12g of n-butylamine 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, TiO2, (hexamethylenediamine + n-butylamine), and water of 1:0.033:0.4:5. Crystallization was performed at 165°C for 80 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 hierarchical titanium silicon molecular sieve.

[0076] The XRD spectra of the above molecular sieves are Figure 1Similar to the titanium silicalite containing mesopores, it has an MFI topological structure and a calculated relative crystallinity of 64%. The N2 physical adsorption characterization results of the 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 18% of the total pore volume, the pore volume with a pore size of 2.0 to 5.0 nm accounted for 37% of the total pore volume, the pore volume with a pore size of 5.0 to 20.0 nm accounted for 32% of the total pore volume, and the pore volume with a pore size greater than 20.0 nm to 50.0 nm accounted for 13% of the total pore volume. The average pore diameter was 3.5 nm, and the total pore volume was 0.54 cm 3 / g, micropore volume is 0.33cm 3 / g, with a specific surface area of ​​531m 2 / g.

[0077] Application Example 5

[0078] 1 g of the molecular sieve prepared in Example 5 was added to a tank reactor, and 10 ml of 30% H2O2, 40 ml of methanol and 10 g of refined naphthalene (sulfur content: 1150 mg / kg) were added in sequence. The mixture was stirred at 70°C for 6 hours.

[0079] The reaction product was sampled and analyzed using a gas phase sulfur and nitrogen analyzer. The reaction results showed that the oxidation removal rate of trace sulfur in refined naphthalene was 99.9%.

[0080] [Example 6]

[0081] 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.

[0082] A mixture of 2.16g of tetrabutyl titanate, 12.80g of tetrapropylammonium bromide, and 3.51g of n-butylamine 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, TiO2, (tetrapropylammonium bromide + n-butylamine) to water of 1:0.033:0.5:4.5. Crystallization was performed at 170°C for 105 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 hierarchical titanium silicon molecular sieve.

[0083] The XRD spectra of the above molecular sieves are Figure 1Similar to the MFI topology, the relative crystallinity is calculated to be 74%. The N2 physical adsorption characterization results of the 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 26% 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 35% 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 4.1 nm, and the total pore volume was 0.55 cm 3 / g, micropore volume is 0.43cm 3 / g, with a specific surface area of ​​551m 2 / g.

[0084] Application Example 6

[0085] 1 g of the molecular sieve prepared in Example 6 was added to a tank reactor, and 10 ml of 30% H2O2, 40 ml of methanol and 10 g of refined naphthalene (sulfur content: 1150 mg / kg) were added in sequence. The mixture was stirred at 70°C for 6 hours.

[0086] The reaction product was sampled and analyzed using a gas phase sulfur and nitrogen analyzer. The reaction results showed that the oxidation removal rate of trace sulfur in refined naphthalene was 99.2%.

[0087] [Example 7]

[0088] 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.

[0089] A mixture of 5.24g of tetrabutyl titanate and 0.95g of cyclohexylamine 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, TiO₂, cyclohexylamine, and water of 1:0.08:0.05:2.4. Crystallization was performed at 175°C for 90 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 hierarchical titanium silicon molecular sieve.

[0090] The XRD spectra of the above molecular sieves are Figure 1Similar to the mesoporous titanium silicalite, it has an MFI topology and a calculated relative crystallinity of 69%. 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 18% of the total pore volume, the pore volume with a pore size of 2.0-5.0 nm accounted for 28% of the total pore volume, the pore volume with a pore size of 5.0-20.0 nm accounted for 40% 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 3.5 nm, and the total pore volume was 0.39 cm 3 / g, micropore volume is 0.36cm 3 / g, with a specific surface area of ​​570m 2 / g.

[0091] Application Example 7

[0092] 1 g of the molecular sieve prepared in Example 7 was added to a tank reactor, and 10 ml of 30% H2O2, 40 ml of methanol and 10 g of refined naphthalene (sulfur content: 1150 mg / kg) were added in sequence. The mixture was stirred at 70°C for 6 hours.

[0093] The reaction product was sampled and analyzed using a gas phase sulfur and nitrogen analyzer. The reaction results showed that the oxidation removal rate of trace sulfur in refined naphthalene was 99.5%.

[0094] [Example 8]

[0095] 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.

[0096] A mixture of 6.55g of tetrabutyl titanate and 0.99g of isopropylamine 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, TiO₂, isopropylamine, and water of 1:0.10:0.09:3. Crystallization was performed at 180°C for 96 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 hierarchical titanium silicalite molecular sieve.

[0097] The XRD spectra of the above molecular sieves are Figure 1Similar to the titanium silicalite molecular sieve containing mesopores, it has an MFI topological structure and a calculated relative crystallinity of 72%. 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 16% of the total pore volume, the pore volume with a pore size of 2.0 to 5.0 nm accounted for 45% 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 12% of the total pore volume. The average pore diameter was 3.8 nm, and the total pore volume was 0.41 cm 3 / g, micropore volume is 0.34cm 3 / g, specific surface area is 507m 2 / g.

[0098] Application Example 8

[0099] 1 g of the molecular sieve prepared in Example 8 was added to a tank reactor, and 10 ml of 30% H2O2, 40 ml of methanol and 10 g of refined naphthalene (sulfur content: 1150 mg / kg) were added in sequence. The mixture was stirred at 70°C for 6 hours.

[0100] The reaction product was sampled and analyzed using a gas phase sulfur and nitrogen analyzer. The reaction results showed that the oxidation removal rate of trace sulfur in refined naphthalene was 99.3%.

[0101] [Example 9]

[0102] 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.

[0103] A mixture of 1.83g titanium tetrachloride, 3.84g tetrapropylammonium bromide, and 0.65g trimethylamine was added to the precursor silicon material, stirred thoroughly, and placed on top of a crystallization kettle. A certain amount of water was added to the bottom of the crystallization kettle to achieve a molar ratio of SiO2, TiO2, (trimethylamine + tetrapropylammonium bromide), and water of 1:0.05:0.15:2.5. Crystallization was performed at 180°C for 82 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 titanium silicon molecular sieve.

[0104] The XRD spectra of the above molecular sieves are Figure 1Similarly, it is a titanium silicalite molecular sieve containing mesopores, with an MFI topological structure and a calculated relative crystallinity of 70%. The multi-level pore titanium silicalite was characterized by the N2 physical adsorption BET method, and a hysteresis loop was observed, confirming the presence of mesopores. The pore volume with a pore diameter less than 2.0 nm accounted for 19% of the total pore volume, the pore volume with a pore diameter of 2.0 to 5.0 nm accounted for 31% of the total pore volume, the pore volume with a pore diameter of 5.0 to 20.0 nm accounted for 36% of the total pore volume, and the pore volume with a pore diameter greater than 20.0 nm to 50.0 nm accounted for 14% of the total pore volume; the average pore diameter was 3.7 nm, and the total pore volume was 0.49 cm 3 / g, micropore volume is 0.31cm 3 / g, with a specific surface area of ​​527m 2 / g.

[0105] Application Example 9

[0106] 1 g of the molecular sieve prepared in Example 9 was added to a tank reactor, and 10 ml of 30% H2O2, 40 ml of methanol and 10 g of refined naphthalene (sulfur content: 1150 mg / kg) were added in sequence. The mixture was stirred at 70°C for 6 hours.

[0107] The reaction product was sampled and analyzed using a gas phase sulfur and nitrogen analyzer. The reaction results showed that the oxidation removal rate of trace sulfur in refined naphthalene was 99.2%.

[0108] [Example 10]

[0109] 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.

[0110] A mixture of 1.49g titanium trichloride, 1.44g ethylenediamine, and 1.37g is added to the precursor silicon material, stirred thoroughly, and placed in the upper portion of a crystallization kettle. A certain amount of water is added to the bottom of the kettle to achieve a molar ratio of SiO2, TiO2, (ethylenediamine + isopropylamine), and water of 1:0.05:0.25:3.5. Crystallization is performed at 170°C for 105 hours to obtain an intermediate crystalline material. This intermediate crystalline material is then filtered, washed with deionized water, dried, and calcined in a muffle furnace at 500°C for 5 hours to obtain a hierarchical titanium silicon molecular sieve.

[0111] The XRD spectra of the above molecular sieves are Figure 1Similar to the titanium silicalite molecular sieve containing mesopores, it has an MFI topological structure and a calculated relative crystallinity of 69%. 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 29% 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 22% 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 3.1 nm, and the total pore volume was 0.38 cm 3 / g, micropore volume is 0.33cm 3 / g, with a specific surface area of ​​534m 2 / g.

[0112] Application Example 10

[0113] 1 g of the molecular sieve prepared in Example 10 was added to a tank reactor, and 10 ml of 30% H2O2, 40 ml of methanol and 10 g of refined naphthalene (sulfur content: 1150 mg / kg) were added in sequence. The mixture was stirred at 70°C for 6 hours.

[0114] The reaction product was sampled and analyzed using a gas phase sulfur and nitrogen analyzer. The reaction results showed that the oxidation removal rate of trace sulfur in refined naphthalene was 99.7%.

[0115] [Comparative Example 1]

[0116] Add 25% tetrapropylammonium hydroxide and tetrapropylammonium bromide to a certain amount of H2O and stir for 0.5 hours to dissolve. Add tetrabutyl titanate dropwise to the above solution and stir at 20°C for 0.5 hours. Then, add tetraethyl orthosilicate dropwise to the above clear solution and stir at 30°C for 1 hour.

[0117] The bright yellow, clear gel obtained by adding the above ingredients was transferred to a 100 ml polytetrafluoroethylene-lined autoclave reactor and crystallized at 170°C for 48 hours. The product was filtered, dried, and calcined in a muffle furnace at 550°C for 2 hours to obtain the synthesized TS-1 molecular sieve product.

[0118] Similar to the test method of the above embodiment, no hysteresis loop was observed in the N2 adsorption-desorption curve. The average pore diameter of the molecular sieve was 1.80 nm and the total pore volume was 0.18 cm 3 / g, micropore volume is 0.08cm 3 / g. The pore volume with a pore size of less than 2.0nm accounts for 61% of the total pore volume, the pore volume with a pore size of 2.0-5.0nm accounts for 32% of the total pore volume, the pore volume with a pore size of 5.0-20.0nm accounts for less than 5% of the total pore volume, and the pore volume with a pore size greater than 20.0nm to 50.0nm accounts for 2% of the total pore volume. The specific surface area of ​​titanium silicalite is 230m 2 / g.

[0119] 1 g of the molecular sieve was added to a tank reactor, and 10 ml of 30% H2O2, 40 ml of methanol and 10 g of refined naphthalene (sulfur content: 1150 mg / kg) were added in sequence. The mixture was stirred at 70°C for 6 hours.

[0120] The reaction product was sampled and analyzed using a gas phase sulfur and nitrogen analyzer. The reaction results showed that the oxidation removal rate of trace sulfur in refined naphthalene was 46.3%.

[0121] [Comparative Example 2]

[0122] Add 38.50 g of 30% silica sol to 173.25 g of H₂O and stir at room temperature until the molar ratio of SiO₂ to H₂O in the gel is 1:50. Adjust the pH of the gel to 9.0 and continue stirring 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.

[0123] A mixture of 1.63g of tetrabutyl titanate, 0.30g of dimethylamine, and 0.49g of n-butylamine 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 crystallization kettle to achieve a molar ratio of SiO2, TiO2, (dimethylamine + n-butylamine), and water of 1:0.025:0.07:2. Crystallization was performed at 180°C for 82 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 titanium silicon molecular sieve.

[0124] The molecular sieve synthesized by this method has an average pore diameter of 2.6 nm and a total pore volume of 0.32 cm 3 / g, micropore volume is 0.20cm 3 / g. The pore volume with a pore diameter of less than 2.0nm accounts for 60% of the total pore volume, the pore volume with a pore diameter of 2.0-5.0nm accounts for 31% of the total pore volume, the pore volume with a pore diameter of 5.0-20.0nm accounts for less than 5% of the total pore volume, and the pore volume with a pore diameter greater than 20.0nm to 50.0nm accounts for 4% of the total pore volume; the specific surface area of ​​titanium silicalite is 312m 2 / g.

[0125] 1 g of the modified molecular sieve was added to a tank reactor, and 10 ml of 30% H2O2, 40 ml of methanol and 10 g of refined naphthalene (sulfur content of 1150 mg / kg) were added in sequence. The mixture was stirred at 70°C for 6 hours.

[0126] The reaction product was sampled and analyzed using a gas phase sulfur and nitrogen analyzer. The reaction results showed that the oxidation removal rate of trace sulfur in refined naphthalene was 42.6%.

[0127] [Comparative Example 3]

[0128] Mix 38.50g of 30% silica sol, 53.13g of anhydrous ethanol, and 7.45g of n-octylamine, stir at room temperature, and add 173.25g 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.

[0129] 1.63g of tetrabutyl titanate, 0.30g of dimethylamine, and 0.49g of n-butylamine were added to the precursor silicon material, mixed thoroughly, and placed in the top of a crystallization kettle. A certain amount of water was added to the bottom of the crystallization kettle to achieve a molar ratio of SiO2, TiO2, (dimethylamine + n-butylamine), and water of 1:0.025:0.07:2. Crystallization was carried out at 180°C for 82 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 titanium silicon molecular sieve.

[0130] The molecular sieves synthesized by this method have an average pore diameter of 2.3 nm and a total pore volume of 0.26 cm 3 / g, micropore volume is 0.18cm 3 / g. The pore volume with a pore diameter less than 2.0nm accounts for 69% of the total pore volume, the pore volume with a pore diameter of 2.0-5.0nm accounts for 24% of the total pore volume, the pore volume with a pore diameter of 5.0-20.0nm accounts for less than 5% of the total pore volume, and the pore volume with a pore diameter greater than 20.0nm to 50.0nm accounts for 2% of the total pore volume; the specific surface area of ​​titanium silicalite is 331m 2 / g.

[0131] 1 g of the modified molecular sieve was added to a tank reactor, and 10 ml of 30% H2O2, 40 ml of methanol and 10 g of refined naphthalene (sulfur content of 1150 mg / kg) were added in sequence. The mixture was stirred at 70°C for 6 hours.

[0132] The reaction product was sampled and analyzed using a gas phase sulfur and nitrogen analyzer. The reaction results showed that the oxidation removal rate of trace sulfur in refined naphthalene was 51.7%.

[0133] [Comparative Example 4]

[0134] 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.

[0135] A mixture of 1.63g of tetrabutyl titanate and 0.80g of n-propylamine was 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 to achieve a molar ratio of SiO2, TiO2, n-propylamine, and water of 1:0.025:0.07:2. Crystallization was performed at 180°C for 82 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 titanium silicon molecular sieve.

[0136] The molecular sieve synthesized by this method has an average pore diameter of 2.3 nm and a total pore volume of 0.25 cm 3 / g, of which the micropore volume is 0.20cm 3 / g. The pore volume with a pore diameter less than 2.0nm accounts for 69% of the total pore volume, the pore volume with a pore diameter of 2.0-5.0nm accounts for 26% of the total pore volume, the pore volume with a pore diameter of 5.0-20.0nm accounts for less than 3% of the total pore volume, and the pore volume with a pore diameter greater than 20.0nm to 50.0nm accounts for 2% of the total pore volume; the specific surface area of ​​titanium silicalite is 285m 2 / g.

[0137] 1 g of the modified molecular sieve was added to a tank reactor, and 10 ml of 30% H2O2, 40 ml of methanol and 10 g of refined naphthalene (sulfur content of 1150 mg / kg) were added in sequence. The mixture was stirred at 70°C for 6 hours.

[0138] The product was sampled and analyzed using a gas phase sulfur and nitrogen analyzer. The reaction results showed that the oxidation removal rate of trace sulfur in refined naphthalene was 53.2%.

[0139] [Comparative Examples 5-7]

[0140] Compared with the above Example 1 and Application Example 1, the difference is that only the crystallization time of the titanium silicon molecular sieve prepared in Comparative Examples 5-7 is changed. The corresponding characterization results are shown in Table 1:

[0141] Table 1

[0142]

[0143]

[0144] [Comparative Examples 8-10]

[0145] Compared with the above Example 1 and Application Example 1, the difference is that only the calcination conditions for preparing titanium silicon molecular sieve in Comparative Examples 8-10 are changed. The corresponding characterization results are shown in Table 2:

[0146] Table 2

[0147] Comparative Example 8 9 10 Calcination temperature (℃) 650 350 600 Calcination time (hours) 3 11 3 Oxidation removal rate of trace sulfur in refined naphthalene % 42.5 52.0 42.1 Is there a hysteresis loop? none none none Average pore diameter (nm) 6.0 5.2 1.7 <![CDATA[Total pore volume (cm 3 / g)]]> 0.26 0.25 0.20 <![CDATA[Micropore volume (cm 3 / g)]]> 0.16 0.14 0.18 <![CDATA[BET specific surface area (m 2 / g)]]> 269 203 238 Pore ​​diameter less than 2.0nm accounts for % of total pore volume 62 68 63 Pore ​​diameter 2.0~5.0nm accounts for % of total pore volume 18 17 20 Pore ​​diameter 5.0~20.0nm accounts for % of total pore volume 17 11 9 Pore ​​diameter greater than 20.0nm to 50.0nm accounts for % of total pore volume 3 4 8

[0148] 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-level pore titanium silicon molecular sieve, characterized in that: The multi-level pores include: micropores and mesopores, and the pore distribution of the multi-level pore titanium silicalite is as follows: the pore volume with a pore diameter 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 45% of the total pore volume, the pore volume with a pore diameter of 5.0 to 20.0 nm accounts for 10% to 40% 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 average pore diameter of the multi-level pore titanium silicalite is 2.8 to 3.9 nm.

2. The molecular sieve according to claim 1, characterized in that The pore distribution of the multi-level pore titanium silicalite is as follows: the volume of pores with a pore diameter of 5.0-20.0 nm accounts for 20%-40% 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 2%-15% of the total pore volume.

3. The molecular sieve according to claim 1 or 2, characterized in that 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 0.18~0.45cm 3 / g.

4. The method for preparing the multi-level pore titanium silicate 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, titanium source, and second template obtained in step (1) are mixed and placed on the top of a crystallization kettle, water is added to the bottom of the crystallization kettle, and crystallization is performed to obtain an intermediate crystalline material; (3) calcining the intermediate crystalline material obtained in step (2) to obtain the multi-level pore titanium silicon molecular sieve.

5. The preparation method according to claim 4, characterized in that In step (1), the molar ratio of the silicon source (in terms of SiO2), the first template, anhydrous ethanol and H2O is 1: (0.1-0.5): (3-10): (20-100); And / or, in step (2), the molar ratio of the precursor material calculated as SiO2, the titanium source calculated as TiO2, the second template and water is 1: (0.02-0.1): (0.05-0.5): (1-5).

6. The preparation method according to claim 4, 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 titanium source is selected from at least one of tetraalkyl titanate or titanium halide; 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 is 10-40°C and the aging time is 12-36 hours; And / or, 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.

8. The preparation method according to claim 4, characterized in that The crystallization conditions are as follows: crystallization temperature is 130-200° C., and crystallization time is 12-100 hours.

9. The preparation method according to claim 4, characterized in that The crystallization conditions are as follows: crystallization temperature is 160-180° C., and crystallization time is 80-120 hours.

10. Use of the molecular sieve according to any one of claims 1 to 3 in the selective oxidation reaction of organic matter in the presence of H2O2.

11. The use according to claim 10, characterized in that The organic selective oxidation reaction with the participation of H2O2 is one or more of the following: oxidation of sulfur-containing organic compounds to sulfones or sulfoxides, epoxidation of olefins, ammoxidation of cyclohexanone, and hydroxylation of phenol.

12. The use according to claim 11, characterized in that The organic selective oxidation reaction with the participation of H2O2 is the oxidation of sulfur-containing organic compounds into sulfones or sulfoxides.

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