Titanium silical catalyst, its preparation method and application

Abstract

This invention provides a titanium-silicon molecular sieve catalyst, its preparation method, and its application, belonging to the field of molecular sieve material preparation technology. The preparation method provided by this invention includes the following steps: adding a silicon source solution and a titanium source solution to a micro-liquid membrane reactor for hydrolysis to obtain a hydrolysate; the silicon source solution includes a soluble silicon source, a template agent, and water, wherein the soluble silicon source includes at least one selected from tetraethyl silicate, silica sol, fumed silica, and silica fume; the titanium source solution includes a titanium source and a dispersant, wherein the titanium source includes at least one selected from tetrabutyl titanate, titanium sulfate, and tetraethyl titanate; subjecting the hydrolysate to a hydrothermal reaction to obtain a hydrothermal product; and calcining the hydrothermal product to obtain the titanium-silicon molecular sieve catalyst. The titanium-silicon molecular sieve catalyst prepared by the method provided by this invention exhibits high catalytic performance in the catalytic oxidation of 1-hexene, with high selectivity for the product 1,2-epoxyhexane.

Description

Technical Field

[0001] This invention belongs to the field of molecular sieve material preparation technology, specifically relating to a titanium-silicon molecular sieve catalyst, its preparation method, and its application. Background Technology

[0002] Titanium silicate molecular sieves (TS-1 molecular sieves) are important catalytic oxidation catalysts. Their green catalytic oxidation system, formed with hydrogen peroxide, is widely used in processes such as olefin epoxidation, aromatic hydrocarbon hydroxylation, ketone ammoniation, and the oxidation of alkanes and alcohols. The TiO4 framework species are the main catalytic active centers in these reactions. Currently, the traditional method for synthesizing TS-1 molecular sieves uses tetrapropylammonium hydroxide (TPAOH) as a template agent, followed by the successive hydrolysis of tetraethyl orthosilicate (TEOS) and titanate esters, and subsequent hydrothermal crystallization. However, in this synthesis process, it is often difficult to effectively control the uniformity of the dispersion of titanium and silicon species in the precursor liquid. Poor dispersion of titanium and silicon species significantly affects the assembly of the molecular sieve framework structural units, reducing the catalytic performance of the final TS-1 molecular sieve. Summary of the Invention

[0003] The purpose of this invention is to provide a titanium-silicon molecular sieve catalyst, its preparation method, and its application. The titanium-silicon molecular sieve catalyst prepared by the method provided by this invention exhibits excellent catalytic performance in the catalytic oxidation of 1-hexene.

[0004] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0005] This invention provides a method for preparing a titanium-silicon molecular sieve catalyst, comprising the following steps:

[0006] A silicon source solution and a titanium source solution are added to a micro-liquid membrane reactor for hydrolysis to obtain a hydrolysate. The silicon source solution includes a soluble silicon source, a template agent, and water. The soluble silicon source includes at least one of tetraethyl silicate, silica sol, fumed silica, and silica fume. The titanium source solution includes a titanium source and a dispersant. The titanium source includes at least one of tetrabutyl titanate, titanium sulfate, and tetraethyl titanate.

[0007] The hydrolysate was subjected to a hydrothermal reaction to obtain a hydrothermal product;

[0008] The hydrothermal product was calcined to obtain a titanium-silicon molecular sieve catalyst.

[0009] Preferably, the template agent comprises tetrapropylammonium hydroxide or tetrapropylammonium bromide; the molar ratio of the soluble silicon source to the template agent is 1.5 to 15:1.

[0010] Preferably, the dispersant includes isopropanol or ethanol; the molar ratio of the titanium source to the dispersant is 0.015 to 0.13:1.

[0011] Preferably, the rotation speed of the microliquid membrane reactor is 3000-6000 rpm; the temperature of the hydrolysis reaction is 20-35℃, and the time is 4-25 min.

[0012] Preferably, the process before the hydrothermal reaction includes: aging the hydrolysate; the aging process is carried out at a temperature of 60–90°C for a time of 6–12 hours.

[0013] Preferably, the hydrothermal reaction is carried out at a temperature of 150–200°C for 6–15 hours.

[0014] Preferably, the calcination temperature is 550–650°C, and the holding time is 4–6 hours; the calcination is carried out in an air atmosphere.

[0015] The present invention provides a titanium-silicon molecular sieve catalyst prepared by the preparation method described above, comprising active Ti species and a molecular sieve framework, wherein the active Ti species exist in the molecular sieve framework in the form of TiO4.

[0016] Preferably, the titanium-silicon molecular sieve catalyst has a particle size of 100–300 nm and a specific surface area of ​​400–550 m². 2 / g; the titanium-silicon molecular sieve catalyst comprises micropores and mesopores, wherein the micropores have a pore size of 0.7–1.5 nm, the mesopores have a pore size of 2–40 nm, and the mesopores have a pore volume of 0.2–0.5 cm³. 2 / g.

[0017] This invention provides the application of the titanium-silicon molecular sieve catalyst described in the above technical solution in the catalytic oxidation reaction of 1-hexene.

[0018] This invention provides a method for preparing a titanium-silicon molecular sieve catalyst, comprising the following steps: adding a silicon source solution and a titanium source solution to a microfluidic membrane reactor for hydrolysis to obtain a hydrolysate; the silicon source solution includes a soluble silicon source, a template agent, and water, wherein the soluble silicon source includes at least one selected from tetraethyl silicate, silica sol, fumed silica, and silica fume; the titanium source solution includes a titanium source and a dispersant, wherein the titanium source includes at least one selected from tetrabutyl titanate, titanium sulfate, and tetraethyl titanate; subjecting the hydrolysate to a hydrothermal reaction to obtain a hydrothermal product; and calcining the hydrothermal product to obtain a titanium-silicon molecular sieve catalyst. In this invention, the high turbulent kinetic energy and turbulent dissipation rate within the microfluidic membrane reactor create a uniform nucleation environment, which is beneficial for exposing active titanium species. Hydrolysis within the microfluidic membrane reactor accelerates the hydrolysis rate of the titanium and silicon sources, promotes molecular sieve nucleation, and shortens the crystallization time. Subsequently, through hydrothermal reaction and calcination, a titanium-silicon molecular sieve catalyst with excellent catalytic performance can be obtained.

[0019] Furthermore, the microfilm reactor can accelerate the hydrolysis of soluble silicon and titanium sources, shortening the time required for conventional hydrolysis reactions. Moreover, after high-speed hydrolysis, highly active titanium-silicon molecular sieve catalysts can be obtained without the need for aging treatment.

[0020] Furthermore, the titanium-silicon molecular sieve catalyst obtained by the preparation method provided by the present invention not only has small particle size, large specific surface area, uniform morphology, and rich pore structure, but also contains a high content of tetracoordinate active titanium species, thereby improving the activity of the titanium-silicon molecular sieve catalyst.

[0021] When the titanium-silicon molecular sieve catalyst provided by this invention is combined with hydrogen peroxide and applied to the catalytic oxidation of 1-hexene, it can promote the contact between 1-hexene and the active sites on the titanium-silicon molecular sieve catalyst. This can both inhibit the ineffective decomposition of hydrogen peroxide and accelerate the removal rate of the catalytic oxidation product 1,2-epoxyhexane, thereby increasing the yield of 1,2-epoxyhexane. Examples show that when the titanium-silicon molecular sieve catalyst provided by this invention is applied to the catalytic oxidation of 1-hexene, the conversion rate of 1-hexene is as high as 35-60%, and the selectivity of 1,2-epoxyhexane is 93-98%. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1X-ray diffraction analysis of titanium-silicon molecular sieve catalysts obtained at different aging times under low rotation speed;

[0024] Figure 2 X-ray diffraction analysis diagrams of titanium-silicon molecular sieve catalysts obtained at high speeds and different aging times;

[0025] Figure 3 SEM image of sample 6000r-0h;

[0026] Figure 4 Here is a scanning electron microscope (SEM) image of the sample taken at 6000 rpm for 6 hours.

[0027] Figure 5 SEM image of sample 6000r-12h;

[0028] Figure 6 Here is a scanning electron microscope (SEM) image of the sample at 3000 r-0 h.

[0029] Figure 7 The image is a scanning electron microscope (SEM) image of the sample taken at 3000 rpm for 6 hours.

[0030] Figure 8 Here is a scanning electron microscope (SEM) image of the sample taken at 3000 rpm for 12 hours.

[0031] Figure 9 The nitrogen adsorption-desorption curves of the titanium-silicon molecular sieve catalyst at high rotational speed are shown.

[0032] Figure 10 The figure shows the catalytic oxidation reaction results of titanium-silicon molecular sieve catalysts obtained at different rotation speeds and aging times;

[0033] Figure 11 The image is a scanning electron microscope (SEM) image of the sample taken at 15 ± 2 min.

[0034] Figure 12 The image is a scanning electron microscope (SEM) image of the sample taken at 15 ± 4 min.

[0035] Figure 13 The image is a scanning electron microscope (SEM) image of the sample taken at 15 ± 6 min.

[0036] Figure 14 The image is a scanning electron microscope (SEM) image of the sample taken at 15 ± 8 min.

[0037] Figure 15 The image is a scanning electron microscope (SEM) image of the sample taken at 10+2 min.

[0038] Figure 16 The image is a scanning electron microscope (SEM) image of the sample taken at 10+4 min.

[0039] Figure 17The image is a scanning electron microscope (SEM) image of the sample taken at 10+6 min.

[0040] Figure 18 The image is a scanning electron microscope (SEM) image of the sample taken at 10+8 min.

[0041] Figure 19 UV absorption spectra at different titanium source hydrolysis times;

[0042] Figure 20 UV absorption spectra at different silicon source hydrolysis times;

[0043] Figure 21 The ultraviolet absorption spectrum is shown when silicon and titanium sources are hydrolyzed simultaneously.

[0044] Figure 22 The image shows a scanning electron microscope (SEM) image of the titanium-silicon molecular sieve obtained in Comparative Example 1. Detailed Implementation

[0045] This invention provides a method for preparing a titanium-silicon molecular sieve catalyst, comprising the following steps:

[0046] A silicon source solution and a titanium source solution are added to a micro-liquid membrane reactor for hydrolysis to obtain a hydrolysate. The silicon source solution includes a soluble silicon source, a template agent, and water. The soluble silicon source includes at least one of tetraethyl silicate, silica sol, fumed silica, and silica fume. The titanium source solution includes a titanium source and a dispersant. The titanium source includes at least one of tetrabutyl titanate, titanium sulfate, and tetraethyl titanate.

[0047] The hydrolysate was subjected to a hydrothermal reaction to obtain a hydrothermal product;

[0048] The hydrothermal product was calcined to obtain a titanium-silicon molecular sieve catalyst.

[0049] In this invention, unless otherwise specified, all raw materials used are commercially available products well known to those skilled in the art or prepared using methods well known to those skilled in the art.

[0050] This invention involves adding a silicon source solution and a titanium source solution to a microfilm reactor for hydrolysis to obtain a hydrolysate. In this invention, the silicon source solution preferably comprises a soluble silicon source, a template agent, and water. The soluble silicon source preferably comprises at least one of tetraethyl silicate, silica sol, fumed silica, and silica, more preferably tetraethyl silicate or silica; the template agent preferably comprises tetrapropylammonium hydroxide or tetrapropylammonium bromide, more preferably tetrapropylammonium hydroxide; and the water is preferably deionized water. The molar ratio of the soluble silicon source to the template agent is preferably 1.5–15:1, more preferably 3.3:1. This invention preferably mixes the soluble silicon source, template agent, and water to obtain a silicon source solution; and mixes the titanium source and a dispersant to obtain a titanium source solution. The concentration of the soluble silicon source in the hydrolysate is preferably 1.24–2.20 mol / L, more preferably 2.20 mol / L. In embodiments of the present invention, a silicon source solution is obtained by mixing tetraethyl tetrasilicate, a 25% (w / w) aqueous solution of tetrapropylammonium hydroxide, and water. In the present invention, the titanium source preferably includes at least one of tetrabutyl titanate, titanium sulfate, and tetraethyl titanate, more preferably tetrabutyl titanate; the dispersant preferably includes isopropanol or ethanol, more preferably isopropanol; the molar ratio of the titanium source to the dispersant is preferably 0.015–0.13:1, more preferably 0.05–0.1:1. The present invention preferably mixes the titanium source and the dispersant to obtain a titanium source solution. In embodiments of the present invention, a titanium source solution is obtained by mixing tetrabutyl titanate and isopropanol. After obtaining the silicon source solution and the titanium source solution, the present invention adds the silicon source solution and the titanium source solution to a microfluidic membrane reactor for hydrolysis to obtain a hydrolysate. In the present invention, the rotation speed of the microfluidic membrane reactor is preferably 3000–6000 rpm, more preferably 4500–6000 rpm, and more preferably 5500–6000 rpm. In this invention, the temperature of the hydrolysis reaction is preferably 20–35°C, more preferably 25–30°C; the time is preferably 4–25 min, more preferably 10–15 min. In this invention, the mixing order of the silicon source solution and the titanium source solution is preferably a first mixing order, a second mixing order, or a third mixing order; specifically, the first mixing order is to add the silicon source solution first, then the titanium source solution; the second mixing order is to add the titanium source solution first, then the silicon source solution; and the third mixing order is to add the silicon source solution and the titanium source solution simultaneously. When using the first mixing order to mix the silicon source solution and the titanium source solution, this invention preferably first adds the silicon source solution to the microfilm reactor for a first-stage hydrolysis reaction to obtain a first material; then the titanium source solution is mixed with the first material to carry out a second-stage hydrolysis reaction.In this invention, the temperatures of the first-stage hydrolysis reaction and the second-stage hydrolysis reaction are preferably 20–35°C, more preferably 25–30°C; the time of the first-stage hydrolysis reaction is preferably 2–15 min, more preferably 5–10 min; and the time of the second-stage hydrolysis reaction is preferably 2–10 min, more preferably 5–8 min. When the silicon source solution and titanium source solution are mixed in a second mixing sequence, this invention preferably first adds the titanium source solution to the microfilm reactor to carry out the third-stage hydrolysis reaction to obtain the second material; then the silicon source solution is mixed with the second material to carry out the fourth-stage hydrolysis reaction. In this invention, the temperatures of the third-stage hydrolysis reaction and the fourth-stage hydrolysis reaction are preferably 20–35°C, more preferably 25–30°C; the time of the third-stage hydrolysis reaction is preferably 2–10 min, more preferably 5–8 min; and the time of the fourth-stage hydrolysis reaction is preferably 2–15 min, more preferably 5–10 min. When the silicon source solution and titanium source solution are mixed in the third mixing sequence, the present invention preferably adds the silicon source solution and titanium source solution simultaneously to the liquid membrane reactor to carry out the fifth-stage hydrolysis reaction. In the present invention, the temperature of the fifth-stage hydrolysis reaction is preferably 20-35°C, more preferably 25-30°C, and the time is preferably 3-15 min, more preferably 5-10 min.

[0051] After obtaining the hydrolysate, the present invention subjectes the hydrolysate to a hydrothermal reaction to obtain a hydrothermal product. The present invention preferably determines whether an aging treatment is required based on specific experimental requirements. In the present invention, the aging treatment temperature is preferably 60–90°C, more preferably 80°C; the time is preferably 6–12 h, specifically 6 h, 9 h, or 12 h. In the present invention, the aging treatment can reduce the particle size of the obtained titanium-silicon molecular sieve catalyst. In the present invention, the hydrothermal reaction is preferably carried out in a high-pressure hydrothermal reactor with a polytetrafluoroethylene liner; the hydrothermal reaction temperature is preferably 150–200°C, more preferably 170°C; the time is preferably 6–15 h, more preferably 12 h. After the hydrothermal reaction, the present invention preferably subjectes the obtained material to centrifugal washing, drying, and grinding sequentially. In the present invention, the reagent used for centrifugal washing is preferably water. The present invention preferably washes until the pH value of the washing liquid is 7. The drying temperature is 60–80°C, more preferably 60°C; the drying time is preferably 8–15 h, more preferably 10–12 h. This invention does not impose any special limitations on the specific grinding method and conditions, as long as they are convenient for subsequent experimental operations.

[0052] After obtaining the hydrothermal product, the present invention calcines the hydrothermal product to obtain a titanium-silicon molecular sieve catalyst. In the present invention, the calcination temperature is preferably 550–650°C, more preferably 580–600°C, and the holding time is 4–6 hours, more preferably 5 hours; the calcination is preferably carried out in an air atmosphere. In the present invention, the calcination is preferably carried out in a muffle furnace.

[0053] This invention provides a titanium-silicon molecular sieve catalyst prepared by the preparation method described above, comprising active Ti species and a molecular sieve framework, wherein the active Ti species exist in the molecular sieve framework in the form of TiO4. In this invention, the titanium-silicon molecular sieve catalyst is preferably an MFI type molecular sieve. In this invention, the particle size of the titanium-silicon molecular sieve catalyst is preferably 100–300 nm, more preferably 150–250 nm; the specific surface area is preferably 400–550 m². 2 / g, more preferably 450-500m 2 / g. In this invention, the titanium-silicon molecular sieve catalyst preferably comprises micropores and mesopores. In this invention, the pore size of the micropores is preferably 0.7–1.5 nm, more preferably 1–1.2 nm; the pore size of the mesopores is preferably 2–40 nm, more preferably 10–25 nm; and the pore volume of the mesopores is preferably 0.2–0.5 cm³. 2 / g, more preferably 0.3-0.4cm 2 / g. The titanium-silicon molecular sieve catalyst of the present invention is preferably an ellipsoidal aggregate. In the present invention, the framework of the titanium-silicon molecular sieve is composed of SiO4 and TiO4 through shared oxygen atom vertices; therefore, the molecular sieve framework contains both framework silicon species and framework titanium species.

[0054] This invention also provides the application of the titanium-silicon molecular sieve catalyst described in the above-mentioned technical solution in the catalytic oxidation reaction of 1-hexene. Preferably, this invention involves mixing the titanium-silicon molecular sieve catalyst, 1-hexene, methanol, and an aqueous hydrogen peroxide solution before carrying out the catalytic oxidation reaction to obtain 1,2-epoxyhexane. In this invention, the mass fraction of hydrogen peroxide in the aqueous hydrogen peroxide solution is preferably 30 wt%. In this invention, the preferred ratio of the titanium-silicon molecular sieve catalyst, 1-hexene, methanol, and aqueous hydrogen peroxide solution is 40–60 mg: 10 mmol: 8–12 mL: 1–1.3 g, more preferably 50 mg: 10 mmol: 10 mL: 1.134 g. The preferred temperature for the catalytic oxidation reaction is 50–70 °C, more preferably 60 °C; the preferred time is 2 h; and the preferred pressure is atmospheric pressure. After the catalytic oxidation reaction, this invention preferably performs solid-liquid separation on the resulting liquid, and the resulting liquid material is 1,2-epoxyhexane. In this invention, the preferred method for solid-liquid separation is filtration.

[0055] Through investigation, this invention found that different hydrolysis sequences and times of silicon and titanium sources, as well as subsequent aging times, all affect the form in which titanium exists in the catalyst; and the degree of hydrolysis resulting from different rotation speeds of the micro-liquid membrane reactor also affects the catalytic oxidation activity of 1-hexene.

[0056] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0057] Example 1

[0058] At 25°C, 90.6 g of tetraethyl silicate, 106.1 g of tetrapropylammonium hydroxide aqueous solution (25 wt%), and 26.6 g of deionized water were added to a microfilm reactor, and the mixture was stirred at 6000 rpm for 2 min. Then, 9.9 g of tetrabutyl titanate was added to 39.2 g of isopropanol, and after thorough dispersion, the resulting dispersion was added to the microfilm reactor, and the mixture was stirred at 6000 rpm for another 2 min to obtain a hydrolysate. The hydrolysate was transferred to a high-pressure hydrothermal reactor with a polytetrafluoroethylene liner and hydrothermally reacted at 170°C for 12 h. After the reaction was complete, the mixture was centrifuged and washed with water until the pH of the washing liquid reached 7, and then dried at 60°C for 12 h. The resulting material was then thoroughly ground to obtain a hydrothermal product. The hydrothermal product was placed in a muffle furnace and calcined in air at 550°C for 6 h to obtain a titanium-silicon molecular sieve catalyst.

[0059] Observation of the titanium-silicon molecular sieve catalyst obtained in this embodiment shows that the catalyst has a microporous structure with a dispersed and uniform morphology; the catalyst exhibits a large ellipsoidal shape with a specific surface area of ​​403 m². 2 / g, and amorphous silica exists around the large-particle-size titanium silica molecular sieve.

[0060] Test Example 1

[0061] 50 mg of the titanium-silicon molecular sieve catalyst obtained in Example 1, 0.842 g of 1-hexene, 10 mL of methanol and 1.134 g of hydrogen peroxide aqueous solution (30 wt%) were added to a three-necked flask equipped with a condenser. The catalytic oxidation reaction was carried out at atmospheric pressure and 60 °C for 2 h. After the reaction was completed, the resulting liquid was filtered and the liquid material was collected to obtain 1,2-epoxyhexane.

[0062] In this test example, the conversion of 1-hexene was 8.9%, and the selectivity for 1,2-epoxyhexane was 91.2%.

[0063] Example 2

[0064] At 25°C, 90.6 g of tetraethyl silicate, 106.1 g of tetrapropylammonium hydroxide aqueous solution (25 wt%), and 26.6 g of deionized water were added to a microfilm reactor and stirred at 3000 rpm for 15 min. Then, 3.3 g of tetrabutyl titanate was added to 13.1 g of isopropanol, and after thorough dispersion, the resulting dispersion was added to the microfilm reactor, and the reaction was continued at 3000 rpm for 10 min to obtain a hydrolysate. The hydrolysate was transferred to a high-pressure hydrothermal reactor with a polytetrafluoroethylene liner and hydrothermally reacted at 150°C for 12 h. After the reaction was completed, the mixture was centrifuged and washed with water until the pH of the washing liquid reached 7, and then dried at 60°C for 12 h. The resulting material was thoroughly ground to obtain a hydrothermal product. The hydrothermal product was placed in a muffle furnace and calcined in air at 650°C for 4 h to obtain a titanium-silicon molecular sieve catalyst.

[0065] Observation of the titanium-silicon molecular sieve catalyst obtained in this embodiment shows that the catalyst has a microporous structure with a dispersed and uniform morphology; the catalyst is ellipsoidal with a major axis of approximately 302 nm, a minor axis of approximately 203 nm, and a specific surface area of ​​429 m². 2 / g.

[0066] Test Example 2

[0067] 50 mg of the titanium-silicon molecular sieve catalyst obtained in Example 2, 0.842 g of 1-hexene, 10 mL of methanol and 1.134 g of hydrogen peroxide aqueous solution (30 wt%) were added to a three-necked flask equipped with a condenser. The catalytic oxidation reaction was carried out at atmospheric pressure and 60 °C for 2 h. After the reaction was completed, the resulting liquid was filtered and the liquid material was collected to obtain 1,2-epoxyhexane.

[0068] In this test example, the conversion of 1-hexene was 25.7%, and the selectivity for 1,2-epoxyhexane was 95.8%.

[0069] Example 3

[0070] At 25°C, 90.6 g of tetraethyl silicate, 106.1 g of tetrapropylammonium hydroxide aqueous solution (25 wt%), and 26.6 g of deionized water were added to a microfilm reactor, and the mixture was stirred at 6000 rpm for 15 min. Then, 29.7 g of tetrabutyl titanate was added to 117.6 g of isopropanol, and after thorough dispersion, the resulting dispersion was added to the microfilm reactor, and the mixture was stirred at 6000 rpm for another 10 min to obtain a hydrolysate. The hydrolysate was transferred to a high-pressure hydrothermal reactor with a polytetrafluoroethylene liner and hydrothermally reacted at 190°C for 12 h. After the reaction was complete, the mixture was centrifuged and washed with water until the pH of the washing liquid reached 7, and then dried at 60°C for 12 h. The resulting material was then thoroughly ground to obtain a hydrothermal product. The hydrothermal product was placed in a muffle furnace and calcined at 600°C in air for 5 h to obtain a titanium-silicon molecular sieve catalyst.

[0071] Observation of the titanium-silicon molecular sieve catalyst obtained in this embodiment shows that it has microporous and mesoporous structures with dispersed and uniform morphology; the titanium-silicon molecular sieve catalyst is ellipsoidal; the major axis is about 287 nm, the minor axis is about 116 nm, and the specific surface area is 505 m². 2 / g.

[0072] Test Example 3

[0073] 50 mg of the titanium-silicon molecular sieve catalyst obtained in Example 3, 0.842 g of 1-hexene, 10 mL of methanol and 1.134 g of hydrogen peroxide aqueous solution (30 wt%) were added to a three-necked flask equipped with a condenser. The catalytic oxidation reaction was carried out at atmospheric pressure and 60 °C for 2 h. After the reaction was completed, the resulting liquid was filtered and the liquid material was collected to obtain 1,2-epoxyhexane.

[0074] In this test example, the conversion of 1-hexene was 34.6%, and the selectivity for 1,2-epoxyhexane was 93.2%.

[0075] Example 4

[0076] At 25°C, 90.6 g of tetraethyl silicate, 106.1 g of tetrapropylammonium hydroxide aqueous solution (25 wt%), and 26.6 g of deionized water were added to a microfilm reactor and stirred at 6000 rpm for 15 min. Then, 9.9 g of tetrabutyl titanate was added to 39.2 g of isopropanol, and after thorough dispersion, the resulting dispersion was added to the microfilm reactor and stirred at 6000 rpm for another 10 min to obtain a hydrolysate. The hydrolysate was transferred to a high-pressure hydrothermal reactor with a polytetrafluoroethylene liner and hydrothermally reacted at 170°C for 12 h. After the reaction was complete, the mixture was centrifuged and washed with water until the pH of the washing liquid reached 7, and then dried at 60°C for 12 h. The resulting material was then thoroughly ground to obtain a hydrothermal product. The hydrothermal product was placed in a muffle furnace and calcined at 550°C in air for 6 h to obtain a titanium-silicon molecular sieve catalyst.

[0077] Observation of the titanium-silicon molecular sieve catalyst obtained in this embodiment shows that it has microporous and mesoporous structures with dispersed and uniform morphology; the titanium-silicon molecular sieve catalyst is ellipsoidal; the major axis is about 265 nm, the minor axis is about 178 nm, and the specific surface area is 474 m². 2 / g.

[0078] Test Example 4

[0079] 50 mg of the titanium-silicon molecular sieve catalyst obtained in Example 4, 0.842 g of 1-hexene, 10 mL of methanol and 1.134 g of hydrogen peroxide aqueous solution (30 wt%) were added to a three-necked flask equipped with a condenser. The catalytic oxidation reaction was carried out at atmospheric pressure and 60 °C for 2 h. After the reaction was completed, the resulting liquid was filtered and the liquid material was collected to obtain 1,2-epoxyhexane.

[0080] In this test example, the conversion of 1-hexene was 61.5%, and the selectivity for 1,2-epoxyhexane was 93.0%.

[0081] Example 5

[0082] At 25°C, 90.6 g of tetraethyl silicate, 106.1 g of tetrapropylammonium hydroxide aqueous solution (25 wt%), and 26.6 g of deionized water were mixed evenly to obtain a silicon source solution. 9.9 g of tetrabutyl titanate was added to 39.2 g of isopropanol and dispersed thoroughly to obtain a titanium source solution. The silicon source solution and the titanium source solution were simultaneously added to a microfilm reactor and stirred at 6000 rpm for 15 min to obtain a hydrolysate. The hydrolysate was transferred to a high-pressure hydrothermal reactor with a polytetrafluoroethylene liner and hydrothermally reacted at 170°C for 12 h. After the reaction was complete, the mixture was washed with water by centrifugation until the pH of the washing solution reached 7, and then dried at 60°C for 12 h. The resulting material was thoroughly ground to obtain a hydrothermal product. The hydrothermal product was placed in a muffle furnace and calcined at 550°C in air for 6 h to obtain a titanium-silicon molecular sieve catalyst.

[0083] Observation of the titanium-silicon molecular sieve catalyst obtained in this embodiment shows that the catalyst has a microporous structure with a dispersed and uniform morphology; the catalyst is ellipsoidal with a major axis of approximately 261 nm, a minor axis of approximately 121 nm, and a specific surface area of ​​477 m². 2 / g.

[0084] Test Example 5

[0085] 50 mg of the titanium-silicon molecular sieve catalyst obtained in Example 5, 0.842 g of 1-hexene, 10 mL of methanol and 1.134 g of hydrogen peroxide aqueous solution (30 wt%) were added to a three-necked flask equipped with a condenser. The catalytic oxidation reaction was carried out at atmospheric pressure and 60 °C for 2 h. After the reaction was completed, the resulting liquid was filtered and the liquid material was collected to obtain 1,2-epoxyhexane.

[0086] In this test example, the conversion of 1-hexene was 30.1%, and the selectivity for 1,2-epoxyhexane was 91.6%.

[0087] Example 6

[0088] At 25°C, 90.6 g of tetraethyl silicate, 106.1 g of tetrapropylammonium hydroxide aqueous solution (25 wt%), and 26.6 g of deionized water were added to a microfluidic membrane reactor and stirred at 3000 rpm for 15 min. Then, 9.9 g of tetrabutyl titanate was added to 39.2 g of isopropanol, and after thorough dispersion, the resulting dispersion was added to the microfluidic membrane reactor and stirred at 3000 rpm for 10 min to obtain the hydrolysate.

[0089] The hydrolysate was transferred to a high-pressure hydrothermal reactor with a polytetrafluoroethylene liner and hydrothermally reacted at 170°C for 12 hours. After the reaction was complete, the mixture was washed with water by centrifugation until the pH of the washing solution reached 7. Then, it was dried at 60°C for 12 hours. The resulting material was thoroughly ground to obtain the hydrothermal product. The hydrothermal product was placed in a muffle furnace and calcined in air at 550°C for 6 hours to obtain a titanium-silicon molecular sieve catalyst (denoted as sample 3000r-0h).

[0090] Example 7

[0091] At 25°C, 90.6 g of tetraethyl silicate, 106.1 g of tetrapropylammonium hydroxide aqueous solution (25 wt%), and 26.6 g of deionized water were added to a microfluidic membrane reactor and stirred at 3000 rpm for 15 min. Then, 9.9 g of tetrabutyl titanate was added to 39.2 g of isopropanol, and after thorough dispersion, the resulting dispersion was added to the microfluidic membrane reactor and stirred at 3000 rpm for 10 min to obtain the hydrolysate.

[0092] The hydrolysate was aged at 80°C for 6 hours. After aging, the resulting material was transferred to a high-pressure hydrothermal reactor with a polytetrafluoroethylene liner and hydrothermally reacted at 170°C for 12 hours. After the reaction, the material was centrifuged and washed with water until the pH of the washing solution reached 7. Then, it was dried at 60°C for 12 hours. The resulting material was thoroughly ground to obtain the hydrothermal product. The hydrothermal product was placed in a muffle furnace and calcined in air at 550°C for 6 hours to obtain a titanium-silicon molecular sieve catalyst (denoted as sample 3000r-6h).

[0093] Example 8

[0094] At 25°C, 90.6 g of tetraethyl silicate, 106.1 g of tetrapropylammonium hydroxide aqueous solution (25 wt%), and 26.6 g of deionized water were added to a microfluidic membrane reactor and stirred at 3000 rpm for 15 min. Then, 9.9 g of tetrabutyl titanate was added to 39.2 g of isopropanol, and after thorough dispersion, the resulting dispersion was added to the microfluidic membrane reactor and stirred at 3000 rpm for 10 min to obtain the hydrolysate.

[0095] The hydrolysate was aged at 80°C for 12 hours. After aging, the resulting material was transferred to a high-pressure hydrothermal reactor with a polytetrafluoroethylene liner and hydrothermally reacted at 170°C for 12 hours. After the reaction, the material was washed with water by centrifugation until the pH of the washing solution reached 7. It was then dried at 60°C for 12 hours. The resulting material was thoroughly ground to obtain the hydrothermal product. The hydrothermal product was placed in a muffle furnace and calcined in air at 550°C for 6 hours to obtain a titanium-silicon molecular sieve catalyst (denoted as sample 3000r⁻¹²h).

[0096] Example 9

[0097] The rotation speed of the microliquid membrane reactor was adjusted to 6000 rpm, and other conditions were the same as in Example 6, to prepare a titanium-silicon molecular sieve catalyst (denoted as sample 6000r-0h).

[0098] Example 10

[0099] The rotation speed of the microliquid membrane reactor was adjusted to 6000 rpm, and other conditions were the same as in Example 7, to prepare a titanium-silicon molecular sieve catalyst (denoted as sample 6000r-6h).

[0100] Example 11

[0101] The rotation speed of the microliquid membrane reactor was adjusted to 6000 rpm, and other conditions were the same as in Example 8, to prepare a titanium-silicon molecular sieve catalyst (denoted as sample 6000r-12h).

[0102] The titanium-silicon molecular sieve catalysts obtained in Examples 6-11 were subjected to phase analysis and textural characterization (i.e., phase analysis and textural characterization of titanium-silicon molecular sieve catalysts obtained under different rotation speed conditions and aging times), and the results are as follows. Figures 1-8 As shown ( Figure 1 X-ray diffraction (XRD) patterns of titanium-silicon molecular sieve catalysts obtained at different aging times under low rotation speeds. Figure 2 X-ray diffraction analysis diagrams of titanium-silicon molecular sieve catalysts obtained at high speeds and different aging times; Figure 3 SEM image of sample 6000r-0h;

[0103] Figure 4 Here is a scanning electron microscope (SEM) image of the sample taken at 6000 rpm for 6 hours. Figure 5 SEM image of sample 6000r-12h; Figure 6 Here is a scanning electron microscope (SEM) image of the sample at 3000 r-0 h. Figure 7 The image is a scanning electron microscope (SEM) image of the sample taken at 3000 rpm for 6 hours. Figure 8 Here are SEM images of the sample taken at 3000 rpm for 12 hours; among them, Figures 3-7The scale bar is 200 nm. Figure 8 The scale bar is 100 nm.

[0104] Depend on Figures 1-2 It can be seen that the titanium-silicon molecular sieve catalysts obtained at different rotation speeds and aging times all showed no impurity peaks, good crystallinity, and a typical topological structure. Figures 3-8 It can be seen that the titanium-silicon molecular sieve catalysts obtained by different rotation speeds and different aging times have uniform morphology and are ellipsoidal, and the particle size of the titanium-silicon molecular sieve catalysts gradually decreases with the extension of aging time.

[0105] Test Example 6

[0106] The performance of the titanium-silicon molecular sieve catalysts obtained in Examples 9-11 was tested:

[0107] 800 mg of the titanium-silicon molecular sieve catalyst obtained in Example 9 (sample 6000 r-0 h) was placed in a spherical sample tube, nitrogen gas was introduced, and a nitrogen adsorption experiment was conducted at 200 °C and 77 K for 12 h. After the experiment, the nitrogen adsorption curve of sample 6000 r-0 h was plotted based on the change in nitrogen volume in the system.

[0108] Replace sample 6000r-0h with the titanium-silicon molecular sieve catalyst obtained in Example 10 (sample 6000r-6h) and the titanium-silicon molecular sieve catalyst obtained in Example 11 (sample 6000r-12h), respectively, while keeping other experimental conditions unchanged, and plot the nitrogen adsorption curves of sample 6000r-6h and sample 6000r-12h.

[0109] The nitrogen adsorption curves for samples at 6000 r⁻⁰ h, 6000 r⁻⁶ h, and 6000 r⁻¹² h are shown in the figure below. Figure 9 As shown. By Figure 9 It can be seen that the isotherms in the nitrogen adsorption curve of the titanium-silicon molecular sieve catalyst are basically of type IUPAC IV; and the nitrogen adsorption process is mainly completed when the relative pressure (p / po) ≤ 0.2, indicating that there are uniform micropores in the titanium-silicon molecular sieve catalyst. The H4 type hysteresis loop in the isotherm curve indicates that there is a coexistence of micropores and slit-like mesopores in the titanium-silicon molecular sieve catalyst.

[0110] Example 12

[0111] The rotation speed of the microliquid membrane reactor was adjusted to 4000 rpm, and other conditions were the same as in Example 6, to prepare a titanium-silicon molecular sieve catalyst (denoted as sample 4000r-0h).

[0112] Example 13

[0113] The rotation speed of the microliquid membrane reactor was adjusted to 4000 rpm, and other conditions were the same as in Example 7, to prepare a titanium-silicon molecular sieve catalyst (denoted as sample 4000r-6h).

[0114] Example 14

[0115] The rotation speed of the microliquid membrane reactor was adjusted to 4000 rpm, and other conditions were the same as in Example 8, to prepare a titanium-silicon molecular sieve catalyst (denoted as sample 4000r-12h).

[0116] Example 15

[0117] The rotation speed of the microliquid membrane reactor was adjusted to 5000 rpm, and other conditions were the same as in Example 6, to prepare a titanium-silicon molecular sieve catalyst (denoted as sample 5000r-0h).

[0118] Example 16

[0119] The rotation speed of the microliquid membrane reactor was adjusted to 5000 rpm, and other conditions were the same as in Example 7, to prepare a titanium-silicon molecular sieve catalyst (denoted as sample 5000r-6h).

[0120] Example 17

[0121] The rotation speed of the microliquid membrane reactor was adjusted to 5000 rpm, and other conditions were the same as in Example 8, to prepare a titanium-silicon molecular sieve catalyst (denoted as sample 5000r-12h).

[0122] Test Example 7

[0123] The performance of the titanium-silicon molecular sieve catalysts obtained in Examples 6-17 was tested:

[0124] 50 mg of the titanium-silicon molecular sieve catalyst obtained in Example 6 (sample 3000 r-0 h), 0.842 g of 1-hexene, 10 mL of methanol, and 1.134 g of hydrogen peroxide aqueous solution (30 wt%) were added to a three-necked flask equipped with a condenser. The catalytic oxidation reaction was carried out at atmospheric pressure and 60 °C for 2 h. After the reaction was completed, the resulting liquid was filtered and the liquid material was collected to obtain 1,2-epoxyhexane.

[0125] The catalytic oxidation of 1-hexene was carried out by replacing sample 3000r-0h with sample 3000r-6h, sample 3000r-12h, sample 4000r-0h, sample 4000r-6h, sample 4000r-12h, sample 5000r-0h, sample 5000r-6h, sample 5000r-12h, sample 6000r-0h, sample 6000r-6h, and sample 6000r-12h, respectively, while keeping other experimental conditions unchanged.

[0126] The catalytic oxidation reaction results of titanium-silicon molecular sieve catalysts obtained at different rotation speeds and aging times are shown in the figure below. Figure 10 As shown. By Figure 10 It can be seen that under low-speed hydrolysis conditions, extending the aging time is beneficial to improving the catalytic performance of titanium-silicon molecular sieve catalysts; however, under high-speed hydrolysis conditions, since hydrolysis is more thorough, extending the aging time is not conducive to improving the catalytic performance of titanium-silicon molecular sieve catalysts.

[0127] Example 18

[0128] (1) At 25°C, 90.6 g of tetraethyl silicate, 106.1 g of tetrapropylammonium hydroxide aqueous solution (25 wt%) and 26.6 g of deionized water were mixed evenly to obtain a silicon source solution; 9.9 g of tetrabutyl titanate was added to 39.2 g of isopropanol and dispersed thoroughly to obtain a titanium source solution. The silicon source solution was added to a micro-liquid membrane reactor and stirred at 6000 rpm for 15 min; then the titanium source solution was added to the micro-liquid membrane reactor and stirred at 6000 rpm. Samples were taken every 2 min for a total of four times to obtain four hydrolysates; the four hydrolysates were transferred to a high-pressure hydrothermal reactor with a polytetrafluoroethylene liner and hydrothermally reacted at 170°C for 12 h; after the reaction was completed, the mixture was centrifuged and washed with water until the pH of the washing liquid was 7, and then dried at 60°C for 12 h. The obtained material was then thoroughly ground to obtain the hydrothermal product. The hydrothermal product was placed in a muffle furnace and calcined in air at 550°C for 6 hours to obtain four titanium-silicon molecular sieve catalysts (the four titanium-silicon molecular sieve catalysts were designated as sample 15+2min, sample 15+4min, sample 15+6min and sample 15+8min, respectively).

[0129] Example 19

[0130] At 25°C, 90.6 g of tetraethyl silicate, 106.1 g of tetrapropylammonium hydroxide aqueous solution (25 wt%), and 26.6 g of deionized water were mixed evenly to obtain a silicon source solution. 9.9 g of tetrabutyl titanate was added to 39.2 g of isopropanol and dispersed thoroughly to obtain a titanium source solution. The titanium source solution was added to a microfluidic membrane reactor and stirred at 6000 rpm for 10 min. Then, the silicon source solution was added to the microfluidic membrane reactor, and stirring continued at 6000 rpm. Samples were taken every 2 min for a total of four samples, yielding four hydrolysates. The four hydrolysates were transferred to a high-pressure hydrothermal reactor with a polytetrafluoroethylene liner and hydrothermally reacted at 170°C for 12 h. After the reaction was complete, the mixture was centrifuged and washed with water until the pH of the washing solution reached 7. The mixture was then dried at 60°C for 12 h. The resulting material was thoroughly ground to obtain the hydrothermal product. The hydrothermal product was placed in a muffle furnace and calcined in air at 550°C for 6 hours to obtain four titanium-silicon molecular sieve catalysts (the four titanium-silicon molecular sieve catalysts were designated as sample 10+2 min, sample 10+4 min, sample 10+6 min and sample 10+8 min, respectively).

[0131] Example 20

[0132] At 25°C, 90.6 g of tetraethyl silicate, 106.1 g of tetrapropylammonium hydroxide aqueous solution (25 wt%), and 26.6 g of deionized water were mixed evenly to obtain a silicon source solution. 9.9 g of tetrabutyl titanate was added to 39.2 g of isopropanol and dispersed thoroughly to obtain a titanium source solution. The silicon and titanium source solutions were simultaneously added to a microfilm reactor and stirred at 6000 rpm. Samples were taken every 3 minutes for a total of four times to obtain four hydrolysates. The four hydrolysates were transferred to a high-pressure hydrothermal reactor with a polytetrafluoroethylene liner and hydrothermally reacted at 170°C for 12 hours. After the reaction was complete, the mixture was centrifuged and washed with water until the pH of the washing solution reached 7. The mixture was then dried at 60°C for 12 hours. The resulting material was thoroughly ground to obtain the hydrothermal product. The hydrothermal product was placed in a muffle furnace and calcined in air at 550°C for 6 hours to obtain four titanium-silicon molecular sieve catalysts (the four titanium-silicon molecular sieve catalysts were designated as sample 3min, sample 6min, sample 9min and sample 12min, respectively).

[0133] Comparative Example 1

[0134] At 25°C, 90.6 g of tetraethyl silicate, 106.1 g of tetrapropylammonium hydroxide aqueous solution (25 wt%), and 26.6 g of deionized water were added to a beaker. A magnetic stirrer was turned on, and the mixture was stirred at 600 rpm for 15 min. Then, 9.9 g of tetrabutyl titanate was added to 39.2 g of isopropanol. After thorough dispersion, the resulting dispersion was added to a beaker containing a silicon source, and the mixture was stirred at 600 rpm for 10 min to obtain a hydrolysate.

[0135] The hydrolysate was aged at 80°C for 6 hours. After aging, the resulting material was transferred to a high-pressure hydrothermal reactor with a polytetrafluoroethylene liner and hydrothermally reacted at 170°C for 12 hours. After the reaction, the material was centrifuged and washed with water until the pH of the washing solution reached 7. Then, it was dried at 60°C for 12 hours. The resulting material was thoroughly ground to obtain the hydrothermal product. The hydrothermal product was placed in a muffle furnace and calcined in air at 550°C for 6 hours to obtain a titanium-silicon molecular sieve catalyst (designated as the control sample).

[0136] Test Example 8

[0137] 50 mg of the control sample obtained from Comparative Example 1, 0.842 g of 1-hexene, 10 mL of methanol and 1.134 g of hydrogen peroxide aqueous solution (30 wt%) were added to a three-necked flask equipped with a condenser. The catalytic oxidation reaction was carried out at atmospheric pressure and 60 °C for 2 h. After the reaction was completed, the resulting liquid was filtered and the liquid material was collected to obtain 1,2-epoxyhexane.

[0138] In this test example, the conversion rate of 1-hexene was 19.4%.

[0139] The phase analysis and texture characterization of the titanium-silicon molecular sieve catalysts obtained in Examples 18-20 were performed respectively, and the results are as follows: Figures 11-21 As shown ( Figure 11 The image is a scanning electron microscope (SEM) image of the sample taken at 15 ± 2 min. Figure 12 The image is a scanning electron microscope (SEM) image of the sample taken at 15 ± 4 min. Figure 13 The image is a scanning electron microscope (SEM) image of the sample taken at 15 ± 6 min. Figure 14 The image is a scanning electron microscope (SEM) image of the sample taken at 15 ± 8 min. Figure 15 The image is a scanning electron microscope (SEM) image of the sample taken at 10+2 min.

[0140] Figure 16 The image is a scanning electron microscope (SEM) image of the sample taken at 10+4 min. Figure 17 The image is a scanning electron microscope (SEM) image of the sample taken at 10+6 min. Figure 18 The image is a scanning electron microscope (SEM) image of the sample taken at 10+8 min. Figure 19 UV absorption spectra at different titanium source hydrolysis times; Figure 20 UV absorption spectra at different silicon source hydrolysis times; Figure 21 This is the UV absorption spectrum of simultaneous hydrolysis of silicon and titanium sources; where, Figures 11-18 The magnification is 200nm.

[0141] Figure 22 The image shows a scanning electron microscope (SEM) image of the titanium-silicon molecular sieve obtained in Comparative Example 1 (magnification: 2 μm).

[0142] Depend on Figures 11-14 It can be seen that when the silicon source is hydrolyzed for 15 minutes first, the complexity of the surface of the titanium-silicon molecular sieve catalyst grains increases with the increase of the titanium source hydrolysis time; from Figure 19 It can be seen that the four samples at 15+2 min, 15+4 min, 15+6 min, and 15+8 min did not have a peak around 320 nm, indicating that there was no titanium dioxide outside the molecular sieve framework. Furthermore, as the hydrolysis time of the titanium source increased, the conversion rate of 1-hexene in the catalytic oxidation reaction increased slightly, while the selectivity of the target product 1,2-epoxyhexane remained basically unchanged, indicating that extending the hydrolysis time of the titanium source helps titanium species enter the molecular sieve framework.

[0143] Depend on Figures 15-18 It can be seen that the surface structure of the sample at 10+8 min is exceptionally rich, formed by the accumulation of small grains; Figure 20 It is known that when the titanium source is hydrolyzed for 10 minutes, the titanium-silicon molecular sieve catalyst exhibits a harmful anatase peak at around 330 nm. This is detrimental to the catalytic oxidation of 1-hexene by the titanium-silicon molecular sieve catalyst, leading to the ineffective decomposition of hydrogen peroxide and reducing the yield of the target product 1,2-epoxyhexane.

[0144] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. People can obtain other embodiments based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for preparing a titanium-silicon molecular sieve catalyst, comprising the following steps: A silicon source solution is added to a microfluidic membrane reactor for a first-stage hydrolysis reaction to obtain a first material; then a titanium source solution is mixed with the first material for a second-stage hydrolysis reaction to obtain a hydrolysate; the silicon source solution includes a soluble silicon source, a template agent, and water, and the soluble silicon source includes at least one of tetraethyl silicate, silica sol, fumed silica, and silica fume; the titanium source solution includes a titanium source and a dispersant, and the titanium source includes at least one of tetrabutyl titanate, titanium sulfate, and tetraethyl titanate. The first stage of hydrolysis reaction takes 5-15 minutes; the second stage of hydrolysis reaction takes 5-10 minutes. The hydrolysate was subjected to a hydrothermal reaction, and the resulting material was successively centrifuged, washed, dried, and ground to obtain a hydrothermal product. The hydrothermal product was calcined to obtain a titanium-silicon molecular sieve catalyst.

2. The preparation method according to claim 1, characterized in that, The template agent includes tetrapropylammonium hydroxide or tetrapropylammonium bromide; the molar ratio of the soluble silicon source to the template agent is 1.5~15:

1.

3. The preparation method according to claim 1, characterized in that, The dispersant includes isopropanol or ethanol; the molar ratio of the titanium source to the dispersant is 0.015~0.13:

1.

4. The preparation method according to claim 1, characterized in that, The rotation speed of the microfluidic membrane reactor is 3000~6000 rpm; the temperature of the first stage hydrolysis reaction and the second stage hydrolysis reaction are independently 20~35℃.

5. The preparation method according to claim 1, characterized in that, The hydrothermal reaction is carried out at a temperature of 150~200℃ for a time of 6~15h.

6. The preparation method according to claim 1, characterized in that, The roasting temperature is 550~650℃, and the holding time is 4~6h; the roasting is carried out in an air atmosphere.

7. The titanium-silicon molecular sieve catalyst prepared by the preparation method according to any one of claims 1 to 6 comprises active Ti species and a molecular sieve framework, wherein the active Ti species exists in the molecular sieve framework in the form of TiO4.

8. The titanium-silicon molecular sieve catalyst according to claim 7, characterized in that, The titanium-silicon molecular sieve catalyst has a particle size of 100-300 nm and a specific surface area of ​​400-550 m². 2 / g; the titanium-silicon molecular sieve catalyst comprises micropores and mesopores, wherein the micropores have a pore size of 0.7~1.5nm, the mesopores have a pore size of 2~40nm, and the mesopores have a pore volume of 0.2~0.5cm³. 2 / g.

9. The application of the titanium-silicon molecular sieve catalyst according to any one of claims 7 to 8 in the catalytic oxidation reaction of 1-hexene.

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