Preparation method of TS-1 molecular sieve for phenol hydroxylation, molecular sieve and application

Abstract

The invention belongs to the technical field of molecular sieve synthesis, and discloses a preparation method of a TS-1 molecular sieve for phenol hydroxylation, which comprises the following steps: dropwise adding tetraethyl orthosilicate into an aqueous solution containing tetrapropylammonium hydroxide; after clarification, dropwise adding a solution containing tetrabutyl titanate and isopropanol into the solution; carrying out hydrothermal crystallization, centrifugation, drying and calcination; the preparation method comprises the following steps: adding silica gel into an aqueous solution of tetrapropylammonium bromide and ethanolamine; dropwise adding a solution containing tetrabutyl titanate and isopropanol into the solution; adding a seed crystal; carrying out hydrothermal crystallization, centrifugation, drying and calcination; dissolving in an aqueous solution of tetrapropylammonium bromide and ethanolamine; and carrying out hydrothermal crystallization, centrifugation, drying and calcination. The method is low in cost and simple to operate, a large number of mesopores are formed in the molecular sieve, the diffusion mass transfer rate is increased, the content of hexa-coordinated titanium is greatly increased, and the catalyst has good catalytic activity in 1-hexene epoxidation, cyclohexene epoxidation, propylene epoxidation and phenol hydroxylation reactions.

Description

Technical Field

[0001] The invention belongs to the technical field of molecular sieve synthesis, and in particular to a preparation method of a TS-1 molecular sieve for phenol hydroxylation, a molecular sieve and an application thereof. Background Art

[0002] TS-1 molecular sieve is a catalyst with good thermal stability and hydrothermal stability. The TS-1 / H2O2 system has the advantages of mild reaction conditions, environmental protection and pollution-free, and the molecular sieve can be reused. Therefore, it has important applications in various oxidation reactions.

[0003] patent [1] The first synthesis of TS-1 was reported. The method uses tetraethyl orthosilicate (TEOS) as the silicon source, tetraethyl titanate (TEOT) as the titanium source, and tetrapropylammonium hydroxide (TPAOH) as the template. The specific operation steps are: in a CO2-free atmosphere, add TEOT to TEOS, slowly add TPAOH (25wt%) aqueous solution, stir the mixture for 1 hour, heat to 80-90°C, and continue to maintain this temperature for 5 hours to remove the generated alcohol; then, add an appropriate amount of distilled water, transfer the resulting uniform sol into a stirred autoclave, and crystallize at an autogenous pressure of 175°C for 10-30 days; take out the autoclave and cool it, wash the obtained crystallized product with hot distilled water, filter it, dry it, and roast it at 550°C for 6 hours to obtain TS-1 raw powder. However, this method requires the raw materials to be of high purity, Na + , K + The alkali metal ion content is as low as possible, and the amount of template agent TPAOH is relatively large, which makes the synthesis cost of TS-1 molecular sieve relatively high.

[0004] In addition, TS-1 synthesized by traditional processes usually has a microporous structure and a large mass transfer resistance, which not only increases the difficulty for phenol to enter the pores of the molecular sieve, resulting in a decrease in the shape selectivity of the molecular sieve, but also further increases the difficulty for the products catechol and hydroquinone to escape from the pores, resulting in the excessive oxidation of the two to benzoquinone, thereby reducing the catalyst's diphenol selectivity.

[0005] In addition, TS-1 synthesized by existing technology is often rich in tetracoordinate titanium and lacks hexacoordinate titanium. Compared with tetracoordinate titanium, hexacoordinate titanium has higher catalytic activity and is more conducive to improving the conversion rate of phenol. Therefore, how to prepare TS-1 rich in hexacoordinate titanium is also a difficult problem with important practical significance. Summary of the invention

[0006] The purpose of the present invention is to overcome the deficiencies in the prior art and to provide a preparation method, molecular sieve and application of TS-1 molecular sieve for phenol hydroxylation.

[0007] The technical solution adopted by the present invention to solve its technical problem is:

[0008] A method for preparing TS-1 molecular sieve for phenol hydroxylation comprises the following synthesis steps:

[0009] (1) adding tetraethyl orthosilicate dropwise into an aqueous solution containing tetrapropylammonium hydroxide;

[0010] (2) After the above solution is clarified, a solution containing tetrabutyl titanate and isopropyl alcohol is added dropwise thereto, and after the hydrolysis is completed, a precursor solution is obtained;

[0011] (3) the obtained solution is charged into a kettle, subjected to hydrothermal crystallization to obtain a crystal product, and finally centrifuged, dried, and calcined to obtain a seed crystal;

[0012] (4) adding silica gel to an aqueous solution of tetrapropylammonium bromide and ethanolamine;

[0013] (5) After the above solution is clarified, the solution containing tetrabutyl titanate and isopropyl alcohol is added dropwise;

[0014] (6) After the hydrolysis is completed, the seed crystals obtained in step (3) are added and stirring is continued to obtain a precursor solution;

[0015] (7) The obtained solution is charged into a kettle, and a crystallized product is obtained after hydrothermal crystallization, and finally centrifuged, dried, and calcined to obtain the parent TS-1 molecular sieve;

[0016] (8) dissolving the parent TS-1 molecular sieve in an aqueous solution of tetrapropylammonium bromide and ethanolamine to obtain a precursor solution;

[0017] (9) The obtained solution is charged into an autoclave, and a crystallized product is obtained after hydrothermal crystallization, and finally centrifuged, dried, and calcined to obtain a multi-level porous TS-1 molecular sieve rich in hexacoordinated titanium, that is, a TS-1 molecular sieve for phenol hydroxylation is obtained.

[0018] Furthermore, the mass concentration of tetrapropylammonium hydroxide in the aqueous solution containing tetrapropylammonium hydroxide in step (1) is 25%, the water is deionized water, the molar ratio of tetrapropylammonium hydroxide to tetraethyl orthosilicate calculated as SiO2 is 0.1-0.5:1, and the molar ratio of deionized water to tetraethyl orthosilicate is 20-50:1.

[0019] Furthermore, in steps (2) and (5), the mass ratio of tetrabutyl titanate to isopropyl alcohol is 0.2-0.3:2.0-3.0, the mass ratio of tetrabutyl titanate to tetraethyl orthosilicate in step (2) is 1:30-50, and the mass ratio of tetrabutyl titanate in step (5) to tetrapropylammonium bromide in step (4) is 1:3-5.

[0020] Furthermore, in step (4), the molar ratio of tetrapropylammonium bromide to silica gel calculated as SiO2 is 0.1-0.5:1, the molar ratio of ethanolamine to silica gel is 0.5-0.5:1, the water is deionized water, and the molar ratio of deionized water to silica gel is 20-50:1.

[0021] Furthermore, the amount of the seed crystals used in step (6) is 2 to 20 wt % of the mass of the silica gel in step (4) calculated as SiO 2;

[0022] Alternatively, the stirring time in step (6) is 12 to 14 hours.

[0023] Further, it is characterized in that in step (8), the mass ratio of tetrapropylammonium bromide to the parent TS-1 molecular sieve is 0.2-0.4:1, the mass ratio of ethanolamine to the parent TS-1 molecular sieve is 0.4-0.6:1, the water is deionized water, and the mass ratio of deionized water to the parent TS-1 molecular sieve is 6-8:1;

[0024] Alternatively, in step (8), the dissolution temperature is 40 to 80° C. and the dissolution time is 2 to 6 hours.

[0025] Furthermore, in steps (3), (7) and (9), the temperature of hydrothermal crystallization is 100-200° C. and the time is 24-72 h; the temperature of calcination is 500-600° C. and the time is 2-8 h.

[0026] The TS-1 molecular sieve is prepared by the preparation method of the TS-1 molecular sieve as described above.

[0027] The use of the TS-1 molecular sieve as described above in catalyzing the hydroxylation reaction of phenol.

[0028] The method for catalyzing the hydroxylation of phenol using the TS-1 molecular sieve as described above comprises the following steps:

[0029] 1) TS-1 molecular sieve, phenol, methanol and hydrogen peroxide are mixed evenly in a round-bottom flask; wherein the mass ratio of TS-1 molecular sieve to phenol is 1:10, and the mass ratio of phenol to methanol is 1:4;

[0030] 2) Place the round-bottom flask in a water bath and stir at a speed of 500 rpm to 1000 rpm until the temperature reaches 50°C to 80°C, add hydrogen peroxide, and start the reaction at a temperature of 50°C to 80°C, normal pressure, and a reaction time of 4h to 6h;

[0031] Wherein, the mass ratio of phenol to hydrogen peroxide is 1:0.4;

[0032] 3) After the reaction is completed, cool to room temperature in a cold water bath.

[0033] The advantages and positive effects achieved by the present invention are:

[0034] 1. The method of the present invention is low in cost and simple to operate. A large number of mesopores are formed inside the molecular sieve, which improves the diffusion mass transfer rate. The content of hexacoordinated titanium is increased from 30% to 50-60%. It has good catalytic activity in 1-hexene epoxidation, cyclohexene epoxidation, propylene epoxidation, and phenol hydroxylation reactions.

[0035] 2. The method of the present invention can improve the catalytic activity of the sample by further increasing the seed content, thereby preparing a molecular sieve with higher catalytic activity for industrial application.

[0036] 3. The raw materials used for post-treatment in the method of the present invention are tetrapropylammonium bromide and ethanolamine, which can be recycled as mother liquor, greatly reducing the synthesis cost and facilitating wide industrial application. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is a TEM image of the hierarchical pore TS-1 molecular sieve rich in hexacoordinated titanium prepared in the present invention;

[0038] Figure 2 The XRD spectrum of the multi-level pore TS-1 molecular sieve rich in hexa-coordinated titanium prepared in the present invention;

[0039] Figure 3 The UV-vis spectrum of the hierarchical pore TS-1 molecular sieve rich in hexacoordinated titanium prepared in the present invention. DETAILED DESCRIPTION

[0040] The present invention will be further described below in conjunction with the embodiments. The following embodiments are descriptive rather than restrictive, and the protection scope of the present invention cannot be limited by the following embodiments.

[0041] The various experimental operations involved in the specific embodiments are all routine techniques in the art. For parts not specially annotated in this document, ordinary technicians in the art can implement them by referring to various commonly used reference books, scientific and technological literature or related instructions, manuals, etc. before the filing date of this invention.

[0042] A method for preparing TS-1 molecular sieve for phenol hydroxylation comprises the following synthesis steps:

[0043] (1) adding tetraethyl orthosilicate dropwise into an aqueous solution containing tetrapropylammonium hydroxide;

[0044] (2) After the above solution is clarified, a solution containing tetrabutyl titanate and isopropyl alcohol is added dropwise thereto, and after the hydrolysis is completed, a precursor solution is obtained;

[0045] (3) the obtained solution is charged into a kettle, subjected to hydrothermal crystallization to obtain a crystal product, and finally centrifuged, dried, and calcined to obtain a seed crystal;

[0046] (4) adding silica gel to an aqueous solution of tetrapropylammonium bromide and ethanolamine;

[0047] (5) After the above solution is clarified, the solution containing tetrabutyl titanate and isopropyl alcohol is added dropwise;

[0048] (6) After the hydrolysis is completed, the seed crystals obtained in step (3) are added and stirring is continued to obtain a precursor solution;

[0049] (7) The obtained solution is charged into a kettle, and a crystallized product is obtained after hydrothermal crystallization, and finally centrifuged, dried, and calcined to obtain the parent TS-1 molecular sieve;

[0050] (8) dissolving the parent TS-1 molecular sieve in an aqueous solution of tetrapropylammonium bromide and ethanolamine to obtain a precursor solution;

[0051] (9) The obtained solution is charged into an autoclave, and a crystallized product is obtained after hydrothermal crystallization, and finally centrifuged, dried, and calcined to obtain a multi-level porous TS-1 molecular sieve rich in hexacoordinated titanium, that is, a TS-1 molecular sieve for phenol hydroxylation is obtained.

[0052] Preferably, the mass concentration of tetrapropylammonium hydroxide in the aqueous solution containing tetrapropylammonium hydroxide in step (1) is 25%, the water is deionized water, the molar ratio of tetrapropylammonium hydroxide to tetraethyl orthosilicate calculated as SiO2 is 0.1-0.5:1, and the molar ratio of deionized water to tetraethyl orthosilicate is 20-50:1.

[0053] Preferably, the mass ratio of tetrabutyl titanate to isopropanol in steps (2) and (5) is 0.2-0.3:2.0-3.0, the mass ratio of tetrabutyl titanate to tetraethyl orthosilicate in step (2) is 1:30-50, and the mass ratio of tetrabutyl titanate in step (5) to tetrapropylammonium bromide in step (4) is 1:3-5.

[0054] Preferably, in step (4), the molar ratio of tetrapropylammonium bromide to silica gel calculated as SiO2 is 0.1-0.5:1, the molar ratio of ethanolamine to silica gel is 0.5-0.5:1, the water is deionized water, and the molar ratio of deionized water to silica gel is 20-50:1.

[0055] Preferably, the amount of seed crystals used in step (6) is 2 to 20 wt % of the mass of silica gel in step (4) calculated as SiO 2;

[0056] Alternatively, the stirring time in step (6) is 12 to 14 hours.

[0057] Preferably, it is characterized in that in step (8), the mass ratio of tetrapropylammonium bromide to the parent TS-1 molecular sieve is 0.2-0.4:1, the mass ratio of ethanolamine to the parent TS-1 molecular sieve is 0.4-0.6:1, the water is deionized water, and the mass ratio of deionized water to the parent TS-1 molecular sieve is 6-8:1;

[0058] Alternatively, in step (8), the dissolution temperature is 40 to 80° C. and the dissolution time is 2 to 6 hours.

[0059] Preferably, in steps (3), (7) and (9), the temperature of hydrothermal crystallization is 100-200°C and the time is 24-72 hours; the temperature of calcination is 500-600°C and the time is 2-8 hours.

[0060] The TS-1 molecular sieve is prepared by the preparation method of the TS-1 molecular sieve as described above.

[0061] The use of the TS-1 molecular sieve as described above in catalyzing the hydroxylation reaction of phenol.

[0062] The method for catalyzing the hydroxylation of phenol using the TS-1 molecular sieve as described above comprises the following steps:

[0063] 1) TS-1 molecular sieve, phenol, methanol and hydrogen peroxide are mixed evenly in a round-bottom flask; wherein the mass ratio of TS-1 molecular sieve to phenol is 1:10, and the mass ratio of phenol to methanol is 1:4;

[0064] 2) Place the round-bottom flask in a water bath and stir at a speed of 500 rpm to 1000 rpm until the temperature reaches 50°C to 80°C, add hydrogen peroxide, and start the reaction at a temperature of 50°C to 80°C, normal pressure, and a reaction time of 4h to 6h;

[0065] Wherein, the mass ratio of phenol to hydrogen peroxide is 1:0.4;

[0066] 3) After the reaction is completed, cool to room temperature in a cold water bath.

[0067] Specifically, the relevant preparation and detection are as follows:

[0068] Example 1

[0069] A method for preparing TS-1 molecular sieve for phenol hydroxylation, the specific steps are as follows:

[0070] (1) Weigh 1.913 g of tetrapropylammonium hydroxide (TPAOH) and prepare a solution with 15.746 g of deionized water. Add 5.360 g of tetraethyl silicate dropwise and stir at room temperature until it becomes clear.

[0071] (2) Weigh 0.218 g of tetrabutyl titanate and add it to 2.200 g of isopropanol. Then, add the mixture dropwise to the solution in step (1) and stir at room temperature for 5 h.

[0072] (3) The system was transferred to a reactor, hydrothermally heated at 170°C for 48 hours, cooled to room temperature, centrifuged at 12500 rpm for 3 minutes with a large amount of deionized water and anhydrous ethanol, washed until the pH was neutral, dried at 80°C for 12 hours, and calcined at 550°C for 6 hours to obtain seed crystals.

[0073] (4) Weigh 0.685 g of tetrapropylammonium bromide and 0.786 g of ethanolamine and add them to 10.300 g of deionized water to prepare a solution. Then, add 5.134 g of silica gel dropwise to the solution and stir at room temperature until the solution becomes clear.

[0074] (5) Weigh 0.228 g of tetrabutyl titanate and add it to 2.200 g of isopropanol. Then, add the mixture dropwise to the solution in step (4) and stir at room temperature for 12 h.

[0075] (6) Weigh 0.127 g of the seed crystals prepared in step (3), add them to the solution in step (5), and stir at room temperature for 12 h.

[0076] (7) The system was transferred to a reactor, hydrothermally heated at 170°C for 48 hours, cooled to room temperature, centrifuged at 12500 rpm for 3 minutes with a large amount of deionized water and anhydrous ethanol, washed until the pH was neutral, and dried at 80°C for 12 hours. The parent TS-1 molecular sieve was calcined at 550°C for 6 hours.

[0077] (8) 1.000 g of the parent TS-1 molecular sieve was weighed and dissolved in a solution prepared by 0.383 g of tetrapropylammonium bromide, 0.510 g of ethanolamine and 7.000 g of deionized water at 60° C. to obtain a precursor solution.

[0078] (9) The system was transferred to a reactor and hydrothermally heated at 170°C for 48 h. After cooling to room temperature, it was centrifuged at 12500 rpm for 3 min with a large amount of deionized water and anhydrous ethanol, washed until the pH was neutral, and dried at 80°C for 12 h. The multi-level pore TS-1 molecular sieve rich in hexacoordinated titanium was obtained by calcining at 550°C for 6 h.

[0079] The method for catalyzing the hydroxylation of phenol using the TS-1 described above comprises the following specific steps:

[0080] 1) Weigh 0.2000 g TS-1, 2.000 g phenol, and 8.000 g methanol, and mix the above system evenly in a round-bottom flask.

[0081] 2) Place the round-bottom flask in a water bath and stir. After heating to 60°C, add 7 mmol of hydrogen peroxide (the molar ratio of phenol to hydrogen peroxide is 3:1). Start the reaction at 60°C, with a rotation speed of 600 rpm and normal pressure for 6 hours.

[0082] 3) After the reaction is completed, cool the mixture to room temperature in a cold water bath to obtain a reaction system.

[0083] The relevant tests are as follows:

[0084] 1. Relevant performance test of TS-1 molecular sieve obtained in Example 1 of the present invention

[0085] Figure 1 This is a transmission electron microscopy image of the TS-1 molecular sieve prepared in Example 1. The results show that the prepared material is indeed rich in a large number of mesopores, and the pore size distribution is 2 to 200 nm.

[0086] Figure 2 This is the XRD spectrum of the TS-1 molecular sieve prepared in Example 1. The results show that the material has typical MFI structural characteristic peaks, and the modified material maintains the original crystal form and relative crystallinity.

[0087] Figure 3 This is the UV-vis spectrum of the TS-1 molecular sieve prepared in Example 1. The results show that the sample contains 50-60% hexacoordinated titanium, 30-40% tetracoordinated titanium and a small amount of anatase TiO2.

[0088] 2. The relevant comparative tests are as follows:

[0089] 0.80 g of ethylbenzene was added as an internal standard to the solution after the reaction (i.e., the reaction system after the hydroxylation of phenol catalyzed by the above-mentioned TS-1), and after being mixed evenly, a small amount of the above-mentioned solution was centrifuged at 10000 rpm for 3 minutes, and then the supernatant was taken for GC analysis. The conversion rate of the reaction and the selectivity of each product were calculated, and the results are shown in Table 1.

[0090] Except that the mass of the seed crystal in step (6) is 0.127 g, 0.159 g and 0.191 g respectively, the other conditions in Example 1, Example 2 and Example 3 are exactly the same; except that the seed crystal is not added in step (6), the other conditions in Comparative Example 1 are exactly the same as those in Example 1; except that tetrapropylammonium bromide is not added in step (8), the other conditions in Comparative Example 2 are exactly the same as those in Example 2; except that ethanolamine is not added in step (8), the other conditions in Comparative Example 3 are exactly the same as those in Example 2. The reaction results are shown in Table 1.

[0091] Table 1

[0092]

[0093]

[0094] [1].Taramasso M.,Perego G.,Notari B.Preparation ofPorous CrystallineSynthetic Material Composed ofSilicon and Titanium Oxides.USPat.4410501,1983.

[0095] [2] Shu Shili, Zhang Shuoxu. Research progress in catalysts for phenol peroxide hydroxylation[J]. Chemical Bulletin, 2015, 78(08): 702-709. DOI: 10.14159 / j.cnki.0441-3776.2015.08.005.

[0096] It can be seen from the data in Table 1 that the catalytic performance of the embodiment, including conversion rate and diphenol selectivity, is much higher than that of the comparative example and the prior art. Specifically, compared with comparative example 1, embodiment 1 has a smaller size due to the addition of seed crystals, so the specific surface area is significantly increased, resulting in more active sites exposed, so its conversion rate is 8.2 times that of comparative example 1, and diphenol selectivity is 3.5 times that of comparative example 1; relative to comparative example 2, embodiment 2 has a multi-level pore molecular sieve with higher crystallinity due to the presence of TPABr template agent in the post-treatment process, that is, it has a more intact MFI molecular sieve structure, so its conversion rate is 2.9 times that of comparative example 2, and diphenol selectivity is 1.5 times that of comparative example 2; relative to comparative example 3, embodiment 2 has a higher basicity due to the presence of ethanolamine in the post-treatment process, which is more conducive to the formation of multi-level pores in the post-treatment process and recrystallization, resulting in more intracrystalline mesopores and a more intact MFI molecular sieve structure, so its conversion rate is 2.8 times that of comparative example 3, and diphenol selectivity is 1.4 times that of comparative example 3.

[0097] More importantly, compared with Example 2, when the amount of seed crystals added was further increased, Example 3 showed a higher conversion rate, which means that the seed crystal content can be further increased to obtain a molecular sieve with higher catalytic activity, which provides important theoretical guidance for the preparation of TS-1 molecular sieves with better catalytic performance in the industrial preparation.

[0098] It can also be seen that in step (8) of the method of the present invention, tetrapropylammonium bromide and ethanolamine have a synergistic effect, which can synergistically improve the relevant properties of the prepared product, especially the tetrapropylammonium bromide and ethanolamine with a mass ratio of 0.383:0.510 have a significant synergistic effect, which can significantly synergistically improve the relevant properties of the prepared product.

[0099] Although the embodiments of the present invention are disclosed for illustrative purposes, those skilled in the art will appreciate that various substitutions, changes and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, the scope of the present invention is not limited to the contents disclosed in the embodiments.

Claims

1. A method for preparing TS-1 molecular sieve for phenol hydroxylation, characterized in that: The method comprises the following synthesis steps: (1) adding tetraethyl orthosilicate dropwise into an aqueous solution containing tetrapropylammonium hydroxide; (2) After the above solution is clarified, a solution containing tetrabutyl titanate and isopropyl alcohol is added dropwise thereto, and after the hydrolysis is completed, a precursor solution is obtained; (3) the obtained solution is charged into a kettle, subjected to hydrothermal crystallization to obtain a crystal product, and finally centrifuged, dried, and calcined to obtain a seed crystal; (4) adding silica gel to an aqueous solution of tetrapropylammonium bromide and ethanolamine; (5) After the above solution is clarified, the solution containing tetrabutyl titanate and isopropyl alcohol is added dropwise; (6) After the hydrolysis is completed, the seed crystals obtained in step (3) are added and stirring is continued to obtain a precursor solution; (7) The obtained solution is charged into a kettle, and a crystallized product is obtained after hydrothermal crystallization, and finally centrifuged, dried, and calcined to obtain the parent TS-1 molecular sieve; (8) dissolving the parent TS-1 molecular sieve in an aqueous solution of tetrapropylammonium bromide and ethanolamine to obtain a precursor solution; (9) The obtained solution is charged into an autoclave, and a crystallized product is obtained after hydrothermal crystallization, and finally centrifuged, dried, and calcined to obtain a multi-level porous TS-1 molecular sieve rich in hexacoordinated titanium, that is, a TS-1 molecular sieve for phenol hydroxylation is obtained.

2. The preparation method according to claim 1, characterized in that: The mass concentration of tetrapropylammonium hydroxide in the aqueous solution containing tetrapropylammonium hydroxide in step (1) is 25%, the water is deionized water, the molar ratio of tetrapropylammonium hydroxide to tetraethyl orthosilicate calculated as SiO2 is 0.1-0.5:1, and the molar ratio of deionized water to tetraethyl orthosilicate is 20-50:

1.

3. The preparation method according to claim 1, characterized in that: The mass ratio of tetrabutyl titanate to isopropanol in steps (2) and (5) is 0.2-0.3:2.0-3.0, the mass ratio of tetrabutyl titanate to tetraethyl orthosilicate in step (2) is 1:30-50, and the mass ratio of tetrabutyl titanate to tetrapropylammonium bromide in step (4) is 1:3-5.

4. The preparation method according to claim 1, characterized in that: In step (4), the molar ratio of tetrapropylammonium bromide to silica gel calculated as SiO2 is 0.1-0.5:1, the molar ratio of ethanolamine to silica gel is 0.5-0.5:1, the water is deionized water, and the molar ratio of deionized water to silica gel is 20-50:

1.

5. The preparation method according to claim 1, characterized in that: The amount of the seed crystals used in step (6) is such that the SiO2 contained therein accounts for 2 to 20 wt% of the mass of the silica gel in step (4) calculated as SiO2; Alternatively, the stirring time in step (6) is 12 to 14 hours.

6. The preparation method according to claim 1, characterized in that: In step (8), the mass ratio of tetrapropylammonium bromide to the parent TS-1 molecular sieve is 0.2-0.4:1, the mass ratio of ethanolamine to the parent TS-1 molecular sieve is 0.4-0.6:1, and the water is deionized water, and the mass ratio of deionized water to the parent TS-1 molecular sieve is 6-8:1; Alternatively, in step (8), the dissolution temperature is 40 to 80° C. and the dissolution time is 2 to 6 hours.

7. The preparation method according to claim 1, characterized in that: In steps (3), (7) and (9), the temperature of hydrothermal crystallization is 100-200° C. and the time is 24-72 hours; the temperature of calcination is 500-600° C. and the time is 2-8 hours.

8. The TS-1 molecular sieve prepared by the method for preparing the TS-1 molecular sieve according to any one of claims 1 to 7.

9. Use of the TS-1 molecular sieve as claimed in claim 8 in catalyzing the hydroxylation reaction of phenol.

10. A method for hydroxylation of phenol using the TS-1 molecular sieve as claimed in claim 8, characterized in that: The steps include: 1) Mix TS-1 molecular sieve, phenol and methanol in a round-bottom flask; wherein the mass ratio of TS-1 molecular sieve to phenol is 1:10, and the mass ratio of phenol to methanol is 1:4; 2) Place the round-bottom flask in a water bath and stir at a speed of 500 rpm to 1000 rpm until the temperature reaches 50°C to 80°C, add hydrogen peroxide, and start the reaction at a temperature of 50°C to 80°C, normal pressure, and a reaction time of 4h to 6h; Wherein, the mass ratio of phenol to hydrogen peroxide is 1:0.4; 3) After the reaction is completed, cool to room temperature in a cold water bath.

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