CN115999645A - Pickering emulsifier and preparation method and application thereof - Google Patents

Abstract

The invention discloses a Pickering emulsifier and its preparation method and application. The invention adopts a hydrothermal crystallization method to synthesize a microporous titanium-silicon molecular sieve, and performs pre-reaction and recrystallization operations on the microporous titanium-silicon molecular sieve to synthesize hollow titanium-silicon Molecular sieves, to enhance their diffusion properties, carry out silanization modification on the hollow titanium-silicon molecular sieves to modify the surface and internal wettability of the pores to synthesize hydrophobic hollow titanium-silicon molecular sieves. Using hydrophobic hollow titanium silicon molecular sieves as Pickering emulsifiers to construct stable Pickering emulsions for epoxidation of 1-hexene and cyclohexene, the conversion rate of 1-hexene and cyclohexene and the epoxy The selectivity of hexane and epoxycyclohexane shortens the reaction time. At the same time, the Pickering emulsion catalyst system is used for epoxidation of 1-hexene and cyclohexene without adding any solvent, which effectively avoids the problems of solvent recovery and product separation and purification, reduces production costs and increases economic benefits .

Description

A kind of Pickering emulsifier and its preparation method and application

technical field

The invention relates to the field of Pickering emulsion catalysis, in particular to a Pickering emulsifier and its preparation method and application.

Background technique

Using titanium-silicon molecular sieves as catalysts and aqueous hydrogen peroxide as an oxidant to catalyze olefins to synthesize epoxy compounds in one step is an important green synthesis process for synthesizing epoxy compounds, which has attracted extensive attention from researchers. Olefins such as 1-hexene, cyclohexene, etc. are typical oil phases, and hydrogen peroxide aqueous solution is a typical water phase. The oil and water phases are immiscible, so it is usually necessary to add acetonitrile as a solvent to form a homogeneous reaction system to improve the olefin phase. Epoxidation effect. However, the solvent reaction system faces many problems such as solvent recovery and product purification. At the same time, the solvent recovery process by rectification operation consumes a lot of energy.

The Pickering emulsion catalytic system is a solvent-free reaction system based on a stable Pickering emulsion. In this system, solid particles are adsorbed on the oil-water phase interface to form a dense particle film to stabilize the dispersed phase droplets and inhibit the droplet The coalescence between them can realize the uniform mixing of the oil-water two phases macroscopically and enhance the interphase transfer. The introduction of the Pickering emulsion catalyst system into the epoxidation of olefins can effectively avoid the addition of organic solvents, thereby enhancing the economic benefits of the reaction process. For the Pickering emulsion catalyst system, the solid particles have dual identities, one is the Pickering emulsifier, and the other is the Pickering catalyst. For emulsifiers, solid particles need to have moderate wettability; for catalysts, solid particles need to have good diffusion properties.

Contents of the invention

Purpose of the invention: the present invention aims to provide a kind of hydrophobic hollow titanium-silicon molecular sieve with moderate wettability and good diffusion properties as Pickering emulsifier; another purpose of the present invention is to provide the preparation method of above-mentioned Pickering emulsifier with application.

Technical solution: The Pickering emulsifier of the present invention is a hydrophobic hollow titanium-silicon molecular sieve with hollow holes of 10-100 nm, and the contact angle of the hydrophobic hollow titanium-silicon molecular sieve is 133.2°-136.5°.

The preparation method of described Pickering emulsifier comprises the steps:

(1) Add tetraethyl silicate dropwise to the tetrapropylammonium hydroxide solution, stir to obtain a transparent solution; add tetrabutyl titanate to the transparent solution, and stir to obtain a precursor solution; place the precursor solution in water Crystallize in a hot kettle, centrifuge the product in the hydrothermal kettle, wash, dry, and calcinate to obtain a microporous titanium-silicon molecular sieve.

(2) After stirring and mixing the obtained microporous titanium-silicon molecular sieve and tetrapropylammonium hydroxide solution, place it in a hydrothermal kettle for crystallization, centrifuge the product in the hydrothermal kettle, wash, dry, and calcinate to obtain hollow titanium Silica Molecular Sieve.

(3) Stir and mix the hollow titanium-silicon molecular sieve and the toluene solution of octadecyltrichlorosilane, conduct a heating reaction, centrifuge the product, wash, and dry to obtain a hydrophobic hollow titanium-silicon molecular sieve, which is The Pickering emulsifier.

Preferably, in step (2), after stirring and mixing the microporous titanium-silicon molecular sieve and the tetrapropylammonium hydroxide solution, a pre-reaction is required, and then the obtained pre-reaction liquid is placed in a hydrothermal kettle for crystallization, and the water The product in the hot kettle is centrifuged, washed, dried, and calcined to obtain a hollow titanium-silicon molecular sieve; wherein, the pre-reaction temperature is 100-120° C., and the pre-reaction time is 2-12 hours.

Further, in step (1), the mass fraction of tetrapropylammonium hydroxide solution is 20-25%, and the molar ratio of tetrapropylammonium hydroxide to tetraethyl silicate is 0.3:1-0.5:1; The molar ratio of tetrabutyl silicate to tetraethyl silicate is 0.03:1-0.05:1; the stirring temperature is from room temperature to 80°C.

Further, the crystallization temperature in step (1) and step (2) is 100-170°C, and the crystallization time is 24-96h; the calcination atmosphere is air or nitrogen, the calcination temperature is 500-550°C, and the heating rate is 2-96 hours. 3°C/min, the calcination time is 6-10h.

Further, in step (2), the mass fraction of tetrapropyl ammonium hydroxide solution is 20-25%, the concentration of tetrapropyl ammonium hydroxide is 0.02-0.3M, microporous titanium silicon molecular sieve and tetrapropyl ammonium hydroxide The solution mass ratio is 1:10-1:30.

Further, in step (3), the mass ratio of the hollow titanium-silicon molecular sieve to octadecyltrichlorosilane is 1:0.1-1:1, the reaction temperature is 60-90° C., and the reaction time is 6-10 hours.

The application of the above-mentioned Pickering emulsifier in the epoxidation reaction of 1-hexene or cyclohexene.

The application of the Pickering emulsifier in the epoxidation reaction of 1-hexene or cyclohexene, the specific steps are as follows: the hydrophobic hollow titanium silicon molecular sieve is dispersed in 1-hexene or cyclohexene to form a dispersion, and 30% hydrogen peroxide aqueous solution is stirred at a high speed to obtain a stable Pickering emulsion, and the temperature is raised to react; 1-hexene corresponds to the preparation of epoxide; cyclohexene corresponds to the preparation of epoxide cyclohexane.

Further, the mass ratio of the hydrophobic hollow titanium-silicon molecular sieve to 1-hexene or cyclohexene is 1:1 to 1:10, the volume ratio of the dispersion to 30% hydrogen peroxide aqueous solution is 1:1 to 4:1, and the mixture is stirred The speed is 8000-12000 rpm, the stirring time is 2-30 minutes, the reaction temperature is 60-100° C., and the reaction time is 2-10 hours.

Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: 1. The present invention synthesizes microporous titanium-silicon molecular sieves by hydrothermal crystallization, and performs pre-reaction and recrystallization operations on microporous titanium-silicon molecular sieves to synthesize hollow titanium Silicon molecular sieves, to enhance their diffusion properties, silanize hollow titanium-silicon molecular sieves to modify the surface and internal wettability of pores to synthesize hydrophobic hollow titanium-silicon molecular sieves; 2. Invent and construct hydrophobic hollow titanium-silicon molecular sieves as Pickering emulsifiers Stable Pickering emulsion catalyst system, epoxidation reaction of 1-hexene and cyclohexene, reaction at 60°C for 2 hours, the conversion rate of 1-hexene is above 20.2%, and the selectivity of epoxide is in 93.3%; the conversion rate of cyclohexene is above 9.1%, and the selectivity of epoxycyclohexane is above 75.5%. The conversion rate of 1-hexene and cyclohexene and the selectivity of 1-hexene and cyclohexene were successfully improved, and the reaction time was shortened; The hexene epoxidation reaction does not add any solvent, effectively avoids problems such as solvent recovery and product separation and purification, reduces production costs, and increases economic benefits.

Description of drawings

(a) in Fig. 1 is the TEM image of the hydrophobic hollow titanium-silicon molecular sieve in Example 1 of the present invention;

(b) in Fig. 1 is the TEM image of the hydrophobic hollow titanium-silicon molecular sieve in Example 2 of the present invention;

(c) in Fig. 1 is the TEM image of the hydrophobic hollow titanium-silicon molecular sieve in Example 3 of the present invention;

(d) in Fig. 1 is the TEM image of the hydrophobic hollow titanium-silicon molecular sieve in Example 4 of the present invention;

Fig. 2 is the infrared spectrogram of the hydrophobic hollow titanium-silicon molecular sieve in Examples 1, 2, 3 and 4 of the present invention;

(a) in Fig. 3 is the contact angle diagram of the hydrophobic hollow titanium-silicon molecular sieve in Example 1 of the present invention;

(b) in Fig. 3 is the contact angle diagram of the hydrophobic hollow titanium-silicon molecular sieve in Example 2 of the present invention;

(c) in Fig. 3 is the contact angle diagram of the hydrophobic hollow titanium-silicon molecular sieve in Example 3 of the present invention;

(d) in Fig. 3 is the contact angle diagram of the hydrophobic hollow titanium-silicon molecular sieve in Example 4 of the present invention;

(a) in Figure 4 is a stable Pickering emulsion droplet diagram formed by the hydrophobic hollow titanium-silicon molecular sieve in Example 1 of the present invention;

(b) in Figure 4 is a stable Pickering emulsion droplet diagram formed by the hydrophobic hollow titanium-silicon molecular sieve in Example 2 of the present invention;

(c) in Figure 4 is a stable Pickering emulsion droplet diagram formed by the hydrophobic hollow titanium-silicon molecular sieve in Example 3 of the present invention;

(d) in FIG. 4 is a droplet diagram of a stable Pickering emulsion formed by the hydrophobic hollow titanium-silicon molecular sieve in Example 4 of the present invention.

Detailed ways

The present invention will be further described below in conjunction with accompanying drawing.

Example 1

(1) Tetraethyl silicate is added dropwise to the tetrapropylammonium hydroxide solution with a mass fraction of 25%. The mol ratio of tetrapropylammonium hydroxide to tetraethylsilicate is 0.3:1. Stir for 3 hours to obtain a clear and transparent solution; add tetrabutyl titanate to the transparent solution, the molar ratio of tetrabutyl titanate to tetraethyl silicate is 0.025:1, stir at room temperature for 2 hours to obtain a precursor solution; Place in a hydrothermal kettle for crystallization, the crystallization temperature is 170°C, and the crystallization time is 48h; the product in the hydrothermal kettle is separated, washed, dried, and calcined in an air atmosphere at a calcination temperature of 550°C and a heating rate of 2.5° C./min, and the calcination time is 6 hours to obtain a microporous titanium-silicon molecular sieve.

(2) Stir and mix the obtained microporous titanium-silicon molecular sieve and 0.3M tetrapropylammonium hydroxide solution, the mass ratio of the microporous titanium-silicon molecular sieve and 0.3M tetrapropylammonium hydroxide solution is 1:10, pre- React for 2 hours; place the obtained pre-reaction solution in a hydrothermal kettle to crystallize, the crystallization temperature is 170°C, and the crystallization time is 48 hours; separate the product in the hydrothermal kettle, wash, dry, and calcinate in an air atmosphere The temperature is 550° C., the heating rate is 2.5° C./min, and the calcination time is 6 hours to obtain a hollow titanium-silicon molecular sieve.

(3) Stir and mix the toluene solution of hollow titanium silicon molecular sieve and octadecyl trichlorosilane, the mass ratio of hollow titanium silicon molecular sieve and octadecyl trichlorosilane is 1:0.2, react at 90°C for 8 hours, and centrifuge the product Separation, washing, and drying to obtain hydrophobic hollow titanium-silicon molecular sieves.

Example 2

(1) Tetraethyl silicate is added dropwise to the tetrapropylammonium hydroxide solution with a mass fraction of 25%. The mol ratio of tetrapropylammonium hydroxide to tetraethylsilicate is 0.3:1. Stir for 3 hours to obtain a clear and transparent solution; add tetrabutyl titanate to the transparent solution, the molar ratio of tetrabutyl titanate to tetraethyl silicate is 0.025:1, stir at room temperature for 2 hours to obtain a precursor solution; Place in a hydrothermal kettle for crystallization, the crystallization temperature is 170°C, and the crystallization time is 48h; the product in the hydrothermal kettle is separated, washed, dried, and calcined in an air atmosphere at a calcination temperature of 550°C and a heating rate of 2.5° C./min, and the calcination time is 6 hours to obtain a microporous titanium-silicon molecular sieve.

(2) Stir and mix the obtained microporous titanium-silicon molecular sieve and 0.3M tetrapropylammonium hydroxide solution, the mass ratio of microporous titanium-silicon molecular sieve and 0.3M tetrapropylammonium hydroxide solution is 1: 10, pre- React for 2 hours; place the obtained pre-reaction solution in a hydrothermal kettle to crystallize, the crystallization temperature is 170°C, and the crystallization time is 48 hours; separate the product in the hydrothermal kettle, wash, dry, and calcinate in an air atmosphere The temperature is 550° C., the heating rate is 2.5° C./min, and the calcination time is 6 hours to obtain a hollow titanium-silicon molecular sieve.

(3) Stir and mix the toluene solution of hollow titanium silicon molecular sieve and octadecyl trichlorosilane, the mass ratio of hollow titanium silicon molecular sieve and octadecyl trichlorosilane is 1:0.2, react at 90°C for 8 hours, and centrifuge the product Separation, washing, and drying to obtain hydrophobic hollow titanium-silicon molecular sieves.

Example 3

(1) Tetraethyl silicate is added dropwise to the tetrapropylammonium hydroxide solution with a mass fraction of 25%. The mol ratio of tetrapropylammonium hydroxide to tetraethylsilicate is 0.3:1. Stir for 3 hours to obtain a clear and transparent solution; add tetrabutyl titanate to the transparent solution, the molar ratio of tetrabutyl titanate to tetraethyl silicate is 0.025:1, stir at room temperature for 2 hours to obtain a precursor solution; Place in a hydrothermal kettle for crystallization, the crystallization temperature is 170°C, and the crystallization time is 48h; the product in the hydrothermal kettle is separated, washed, dried, and calcined in an air atmosphere at a calcination temperature of 550°C and a heating rate of 2.5° C./min, and the calcination time is 6 hours to obtain a microporous titanium-silicon molecular sieve.

(2) Stir and mix the obtained microporous titanium-silicon molecular sieve and 0.3M tetrapropylammonium hydroxide solution, the mass ratio of microporous titanium-silicon molecular sieve and 0.3M tetrapropylammonium hydroxide solution is 1: 10, pre- React for 12 hours; place the obtained pre-reaction liquid in a hydrothermal kettle for crystallization, the crystallization temperature is 170°C, and the crystallization time is 48 hours; separate the product in the hydrothermal kettle, wash, dry, and calcinate in an air atmosphere. The temperature is 550° C., the heating rate is 2.5° C./min, and the calcination time is 6 hours to obtain a hollow titanium-silicon molecular sieve.

(3) Stir and mix the toluene solution of hollow titanium silicon molecular sieve and octadecyl trichlorosilane, the mass ratio of hollow titanium silicon molecular sieve and octadecyl trichlorosilane is 1:0.2, react at 90°C for 8 hours, and centrifuge the product Separation, washing, and drying to obtain hydrophobic hollow titanium-silicon molecular sieves.

Example 4

(1) Tetraethyl silicate is added dropwise to the tetrapropylammonium hydroxide solution with a mass fraction of 25%. The mol ratio of tetrapropylammonium hydroxide to tetraethylsilicate is 0.3:1. Stir for 3 hours to obtain a clear and transparent solution; add tetrabutyl titanate to the transparent solution, the molar ratio of tetrabutyl titanate to tetraethyl silicate is 0.025:1, stir at room temperature for 2 hours to obtain a precursor solution; Place in a hydrothermal kettle for crystallization, the crystallization temperature is 170°C, and the crystallization time is 48h; the product in the hydrothermal kettle is separated, washed, dried, and calcined in an air atmosphere at a calcination temperature of 550°C and a heating rate of 2.5° C./min, and the calcination time is 6 hours to obtain a microporous titanium-silicon molecular sieve.

(2) The obtained microporous titanium silicon molecular sieve and 0.3M tetrapropyl ammonium hydroxide solution are stirred and mixed, and the mass ratio of microporous titanium silicon molecular sieve and 0.3M tetrapropyl ammonium hydroxide solution is 1: 10; The liquid is placed in a hydrothermal kettle for crystallization, the crystallization temperature is 170°C, and the crystallization time is 48h; the product in the hydrothermal kettle is separated, washed, dried, and calcined in an air atmosphere at a calcination temperature of 550°C and a heating rate of 2.5° C./min, and the calcination time is 6 hours to obtain a hollow titanium-silicon molecular sieve.

(3) Stir and mix the toluene solution of hollow titanium silicon molecular sieve and octadecyl trichlorosilane, the mass ratio of hollow titanium silicon molecular sieve and octadecyl trichlorosilane is 1:0.2, react at 90°C for 8 hours, and centrifuge the product Separation, washing, and drying to obtain hydrophobic hollow titanium-silicon molecular sieves.

Comparative example 1

Tetraethyl silicate was added dropwise to the tetrapropylammonium hydroxide solution with a mass fraction of 25%, the molar ratio of tetrapropylammonium hydroxide to tetraethylsilicate was 0.3:1, and stirred at room temperature for 3h, Obtain a clear and transparent solution; add tetrabutyl titanate to the transparent solution, the molar ratio of tetrabutyl titanate to tetraethyl silicate is 0.025:1, stir at room temperature for 2 hours to obtain a precursor solution; place the precursor solution in water Carry out crystallization in a hot kettle, the crystallization temperature is 170°C, and the crystallization time is 48h; the product in the hydrothermal kettle is separated, washed, dried, and calcined in an air atmosphere at a calcination temperature of 550°C and a heating rate of 2.5°C/ min, the calcination time is 6h, and the microporous titanium silicon molecular sieve is obtained.

Comparative example 2

(1) Tetraethyl silicate is added dropwise to the tetrapropylammonium hydroxide solution with a mass fraction of 25%. The mol ratio of tetrapropylammonium hydroxide to tetraethylsilicate is 0.3:1. Stir for 3 hours to obtain a clear and transparent solution; add tetrabutyl titanate to the transparent solution, the molar ratio of tetrabutyl titanate to tetraethyl silicate is 0.025:1, stir at room temperature for 2 hours to obtain a precursor solution; Place in a hydrothermal kettle for crystallization, the crystallization temperature is 170°C, and the crystallization time is 48h; the product in the hydrothermal kettle is separated, washed, dried, and calcined in an air atmosphere at a calcination temperature of 550°C and a heating rate of 2.5° C./min, and the calcination time is 6 hours to obtain a microporous titanium-silicon molecular sieve.

(2) The obtained microporous titanium silicon molecular sieve and 0.3M tetrapropyl ammonium hydroxide solution are stirred and mixed, and the mass ratio of microporous titanium silicon molecular sieve and 0.3M tetrapropyl ammonium hydroxide solution is 1: 10; The liquid is placed in a hydrothermal kettle for crystallization, the crystallization temperature is 170°C, and the crystallization time is 48h; the product in the hydrothermal kettle is separated, washed, dried, and calcined in an air atmosphere at a calcination temperature of 550°C and a heating rate of 2.5° C./min, and the calcination time is 6 hours to obtain a hollow titanium-silicon molecular sieve.

Comparative example 3

(1) Tetraethyl silicate is added dropwise to the tetrapropylammonium hydroxide solution with a mass fraction of 25%. The mol ratio of tetrapropylammonium hydroxide to tetraethylsilicate is 0.3:1. Stir for 3 hours to obtain a clear and transparent solution; add tetrabutyl titanate to the transparent solution, the molar ratio of tetrabutyl titanate to tetraethyl silicate is 0.025:1, stir at room temperature for 2 hours to obtain a precursor solution; Place in a hydrothermal kettle for crystallization, the crystallization temperature is 170°C, and the crystallization time is 48h; the product in the hydrothermal kettle is separated, washed, dried, and calcined in an air atmosphere at a calcination temperature of 550°C and a heating rate of 2.5° C./min, and the calcination time is 6 hours to obtain a microporous titanium-silicon molecular sieve.

(2) Stir and mix the toluene solution of microporous titanium silicon molecular sieve and octadecyl trichlorosilane, the mass ratio of hollow titanium silicon molecular sieve and octadecyl trichlorosilane is 1:0.2, react at 90°C for 8h, and the product Centrifugal separation, washing, and drying to obtain hydrophobic microporous titanium-silicon molecular sieves.

test case 1

This test example is used to illustrate the reaction effect of the molecular sieve obtained by the method provided by the present invention and the molecular sieve obtained by the method of the comparative example used in the epoxidation reaction of 1-hexene.

The titanium-silicon molecular sieve samples prepared in the above examples and comparative examples were stirred according to the sample: 1-hexene mass ratio of 1:5 to prepare a dispersion liquid, mixed with 30% hydrogen peroxide aqueous solution, and stirred at a rate of 12000 rpm , stirred for 30 minutes to obtain a Pickering emulsion, the volume ratio of the dispersion to the aqueous hydrogen peroxide solution was 1:1, the temperature was raised to 60°C, and the reaction was carried out for 2 hours to prepare hexane oxide, and the obtained product was used on the Shimadzu GC-2014C -17 capillary column was used to measure the distribution of each product, and the results are shown in Table 1.

in:

Table 1

catalyst 1-Hexene Conversion (%) Hexylene oxide selectivity (%) Example 1 23.3 96.3 Example 2 21.8 95.4 Example 3 20.2 93.3 Example 4 10.6 88.5 Comparative example 1 2.1 52.8 Comparative example 2 4.6 70.9 Comparative example 3 3.8 67.6

As can be seen from Table 1, the catalytic activity of the hydrophobic hollow titanium-silicon molecular sieve prepared by the method of the present invention is high, and when used in the epoxidation reaction of 1-hexene, the conversion rate of 1-hexene and the selectivity of hexane oxide are all obvious higher than the comparative example.

test case 2

This test example is used to illustrate the reaction effect of the molecular sieve obtained by the method provided by the present invention and the molecular sieve obtained by the method of the comparative example used in the cyclohexene epoxidation reaction.

Stir the titanium-silicon molecular sieve samples prepared in the above examples and comparative examples according to the sample: cyclohexene mass ratio of 1:5 to prepare a dispersion, mix with 30% hydrogen peroxide aqueous solution, and stir at 12000 rpm. Stir for 30 minutes to obtain a Pickering emulsion, the volume ratio of the dispersion to the aqueous hydrogen peroxide solution is 1:1, heat up to 60°C, and react for 2 hours to prepare epoxycyclohexane, and the resulting product is used on a Shimadzu GC-2014C -17 capillary column was used to measure the distribution of each product, and the results are shown in Table 2.

in:

Table 2

catalyst Cyclohexene conversion (%) Epoxy cyclohexane selectivity (%) Example 1 10.3 81.4 Example 2 9.1 75.5 Example 3 9.2 78.3 Example 4 2.6 55.2 Comparative example 1 0.3 22.6 Comparative example 2 0.6 47.5 Comparative example 3 0.4 38.7

As can be seen from Table 2, the hydrophobic hollow titanium-silicon molecular sieve prepared by the method of the present invention has high catalytic activity, and when used in the cyclohexene epoxidation reaction, the conversion rate of cyclohexene and the selectivity of epoxy cyclohexane are significantly high in the comparative example.

Claims (10)

1. A Pickering emulsifier, characterized in that the Pickering emulsifier is a hydrophobic hollow titanium-silicon molecular sieve with hollow holes of 10 to 100 nm, and the contact angle of the hydrophobic hollow titanium-silicon molecular sieve is 133.2 ° to 136.5 °. 2. the preparation method of Pickering emulsifier according to claim 1, is characterized in that, comprises the steps: (1) Add tetraethyl silicate dropwise to the tetrapropylammonium hydroxide solution, stir to obtain a transparent solution; add tetrabutyl titanate to the transparent solution, and stir to obtain a precursor solution; place the precursor solution in water Crystallize in a hot kettle, centrifuge the product in the hydrothermal kettle, wash, dry, and calcinate to obtain a microporous titanium-silicon molecular sieve. (2) After stirring and mixing the obtained microporous titanium-silicon molecular sieve and tetrapropylammonium hydroxide solution, place it in a hydrothermal kettle for crystallization, centrifuge the product in the hydrothermal kettle, wash, dry, and calcinate to obtain hollow titanium Silica Molecular Sieve. (3) Stir and mix the hollow titanium-silicon molecular sieve and the toluene solution of octadecyltrichlorosilane, conduct a heating reaction, centrifuge the product, wash, and dry to obtain a hydrophobic hollow titanium-silicon molecular sieve, which is The Pickering emulsifier. 3. according to the preparation method of the described Pickering emulsifier of claim 2, it is characterized in that, in step (2), after microporous titanium silicon molecular sieve and tetrapropyl ammonium hydroxide solution stirring and mixing, need carry out pre-reaction, Then put the obtained pre-reaction solution in a hydrothermal kettle for crystallization, centrifuge the product in the hydrothermal kettle, wash, dry, and calcinate to obtain a hollow titanium-silicon molecular sieve; wherein, the pre-reaction temperature is 100-120°C, and the pre-reaction The time is 2 to 12 hours. 4. according to the preparation method of the described Pickering emulsifier of claim 2, it is characterized in that, in step (1), the massfraction of tetrapropyl ammonium hydroxide solution is 20～25%, tetrapropyl ammonium hydroxide and The molar ratio of tetraethyl silicate is 0.3:1-0.5:1; the molar ratio of tetrabutyl titanate to tetraethyl silicate is 0.03:1-0.05:1; the stirring temperature is from room temperature to 80°C. 5. according to the preparation method of the described Pickering emulsifier of claim 2, it is characterized in that, in step (1) and step (2), crystallization temperature is 100～170 ℃, and crystallization time is 24～96h; Calcination atmosphere It is air or nitrogen, the calcination temperature is 500-550°C, the heating rate is 2-3°C/min, and the calcination time is 6-10h. 6. according to the preparation method of the described Pickering emulsifier of claim 2, it is characterized in that, in step (2), the massfraction of tetrapropyl ammonium hydroxide solution is 20～25%, tetrapropyl ammonium hydroxide concentration 0.02-0.3M, and the mass ratio of microporous titanium-silicon molecular sieve and tetrapropyl ammonium hydroxide solution is 1:10-1:30. 7. according to the preparation method of the described Pickering emulsifier of claim 2, it is characterized in that, in step (3), hollow titanium silicon molecular sieve and octadecyl trichlorosilane mass ratio are 1: 0.1～1: 1, The reaction temperature is 60-90°C, and the reaction time is 6-10 hours. 8. The application of the Pickering emulsifier described in claims 1 to 7 in the epoxidation reaction of 1-hexene or cyclohexene. 9. The application according to claim 8, characterized in that the hydrophobic hollow titanium silicon molecular sieve is dispersed in 1-hexene or cyclohexene to form a dispersion liquid, and stirred at a high speed with 30% hydrogen peroxide aqueous solution to obtain a stable skin Kling emulsion, temperature rise reaction; 1-hexene corresponds to the preparation of epoxyhexane; cyclohexene corresponds to the preparation of epoxycyclohexane. 10. The application according to claim 8, characterized in that the mass ratio of the hydrophobic hollow titanium-silicon molecular sieve to 1-hexene or cyclohexene is 1:1 to 1:10, and the dispersion liquid and 30% hydrogen peroxide aqueous solution The volume ratio is 1:1-4:1, the stirring rate is 8000-12000 rpm, the stirring time is 2-30 minutes, the reaction temperature is 60-100° C., and the reaction time is 2-10 hours.

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