Catalyst for gas-phase epoxidation of propylene and preparation method thereof, and gas-phase epoxidation method of propylene

Abstract

The present invention relates to the technical field of propylene gas phase epoxidation, and in particular to a catalyst for propylene gas phase epoxidation and a preparation method thereof and a propylene gas phase epoxidation method, wherein the method comprises: under the condition of pH 6-10, titanium silicon molecular sieve, a boron-containing auxiliary agent and a chloroauric acid aqueous solution are mixed and stirred to obtain a suspension; in a hydrogen atmosphere, the filter residue obtained by filtering the suspension is roasted to obtain a catalyst for propylene gas phase epoxidation; wherein the boron-containing auxiliary agent is selected from at least one of boric acid, borax and sodium metaborate. The present invention can increase the content of gold nanoparticles with a particle size of 1-2nm in the catalyst by adding a boron-containing auxiliary agent during the process of loading gold, and improve the selectivity of propylene in the propylene gas phase epoxidation reaction.

Description

Technical Field

[0001] The invention relates to the technical field of propylene gas phase epoxidation, and in particular to a catalyst for propylene gas phase epoxidation and a preparation method thereof and a propylene gas phase epoxidation method. Background Art

[0002] Propylene oxide is the third largest propylene derivative after polypropylene and acrylonitrile. It is mainly used to produce polyether polyols, propylene glycol and various non-ionic surfactants. The current production methods of propylene oxide mainly include chlorohydrin method, co-oxidation method, hydrogen peroxide oxidation method (HPPO), etc. Among them, the chlorohydrin method is the most mature technology, but it produces a large amount of solid waste and wastewater, causing serious environmental pollution. The co-oxidation method and HPPO method are booming, but there are also certain problems: the co-oxidation method will produce a large number of co-products, and the efficiency of the device is greatly affected by the price fluctuations of the co-products; the HPPO method has problems such as short catalyst life, high energy consumption, and the need for matching H2O2.

[0003] The most ideal process for synthesizing propylene oxide is to use O2 as an oxidant to carry out gas-phase epoxidation of propylene. However, it is too difficult and there is no research result with industrialization prospects reported so far. If a reducing activator such as H2 is added to the reaction system, the dissociation activation energy of O2 will be greatly reduced. Under the action of catalysts such as gold and silver, the degree of epoxidation can also be better controlled. Therefore, the direct gas-phase epoxidation of propylene to synthesize propylene oxide using hydrogen and oxygen in situ has always been a hot topic of research and has the best industrialization prospects.

[0004] Haruta et al. reported the synthesis of propylene oxide in one step using Au / TiO2 catalyst synthesized by deposition-precipitation method in the coexistence of propylene, H2 and O2. Currently, Au / TS-1 catalyst has the best effect in propylene gas phase epoxidation, but the catalysts all have problems such as short lifespan, generally less than 100 hours, and low selectivity to propylene oxide. Summary of the invention

[0005] The purpose of the present invention is to overcome the technical problems that the existing catalyst for propylene gas phase epoxidation is easy to deposit carbon, has a short service life and low selectivity for propylene oxide, and to provide a catalyst for propylene gas phase epoxidation and a preparation method thereof and a propylene gas phase epoxidation method.

[0006] In order to achieve the above object, the first aspect of the present invention provides a method for preparing a catalyst for gas-phase epoxidation of propylene, the method comprising:

[0007] (1) mixing and stirring a titanium silicon molecular sieve, a boron-containing auxiliary agent and an aqueous solution of chloroauric acid at a pH of 6-10 to obtain a suspension;

[0008] (2) calcining the filter residue obtained by filtering the suspension in a hydrogen atmosphere to obtain a propylene gas-phase epoxidation catalyst;

[0009] Wherein, the boron-containing auxiliary agent is selected from at least one of boric acid, borax and sodium metaborate.

[0010] The second aspect of the present invention provides a catalyst for gas-phase epoxidation of propylene prepared according to the method described in the first aspect.

[0011] The third aspect of the present invention provides a method for gas-phase epoxidation of propylene, comprising: mixing propylene, hydrogen, oxygen and nitrogen for reaction in the presence of a catalyst, wherein the catalyst comprises the catalyst for gas-phase epoxidation of propylene described in the second aspect.

[0012] Through the above technical scheme, the present invention can increase the content of gold nanoparticles with a particle size of 1-2nm in the catalyst by adding a boron-containing auxiliary agent during the process of loading gold on the titanium silicon molecular sieve, thereby improving the selectivity of propylene in the propylene gas phase epoxidation reaction. DETAILED DESCRIPTION

[0013] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0014] As mentioned above, the first aspect of the present invention provides a method for preparing a propylene gas phase epoxidation catalyst, the method comprising:

[0015] (1) mixing and stirring a titanium silicon molecular sieve, a boron-containing auxiliary agent and an aqueous solution of chloroauric acid at a pH of 6-10 to obtain a suspension;

[0016] (2) calcining the filter residue obtained by filtering the suspension in a hydrogen atmosphere to obtain a propylene gas-phase epoxidation catalyst;

[0017] Wherein, the boron-containing auxiliary agent is selected from at least one of boric acid, borax and sodium metaborate.

[0018] In the present invention, the borax may be at least one of sodium tetraborate decahydrate, sodium tetraborate pentahydrate and anhydrous sodium tetraborate.

[0019] In the present invention, the boron-containing auxiliary agent can improve the dispersion and stability of gold during the loading process, and is helpful to form gold nanoparticles with smaller particles, thereby improving the catalyst performance of the propylene gas phase epoxidation catalyst.

[0020] According to the present invention, under preferred conditions, the weight ratio of the chloroauric acid aqueous solution to the chloroauric acid aqueous solution is 100:(0.04-1) in terms of gold.

[0021] According to the present invention, under preferred conditions, the molar ratio of the boron-containing auxiliary agent to the aqueous chloroauric acid solution is (1-10):1, for example, it can be 1:1, 2:1, 3:1, 5:1, 7:1, 8:1, 10:1 or any value in the range formed by any two of the above ratios, preferably (1-7:1).

[0022] In the present invention, the concentration of the chloroauric acid aqueous solution can be selected within a wide range. Under preferred conditions, the concentration of chloroauric acid in the chloroauric acid aqueous solution is 0.005-0.5 mol / L, for example, it can be 0.005 mol / L, 0.01 mol / L, 0.05 mol / L, 0.1 mol / L, 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, 0.5 mol / L or any value in the range formed by any two of the above values.

[0023] According to the present invention, the titanium silicate molecular sieve can be evenly dispersed by stirring, thereby improving the uniformity of the loading of gold nanoparticles on the surface of the titanium silicate molecular sieve. Under preferred conditions, the stirring conditions include: a temperature of 40-70° C. and a time of 5-36 hours.

[0024] According to the present invention, under preferred conditions, in step (2), the calcination conditions include: temperature of 100-350°C, time of 2-8h; preferably, temperature of 150-250°C, time of 3-5h.

[0025] In the present invention, the titanium silicalite molecular sieve may be a titanium silicalite molecular sieve disclosed in the prior art, or may be prepared by a specific method. In some preferred embodiments of the present invention, in order to optimize the catalytic activity of the propylene gas phase epoxidation catalyst, the preparation method of the titanium silicalite molecular sieve comprises:

[0026] The silicon source, the alkaline template, the titanium source and water are mixed uniformly to obtain a titanium silical sol; the compound represented by formula (I) is then added to the titanium silical sol, and the obtained mixture is hydrothermally crystallized and calcined;

[0027]

[0028] Formula (I)

[0029] wherein i is an integer from 1 to 10; R1, R2 and R3 are each independently selected from a C1-C6 alkyl group;

[0030] In the present invention, the C1-C6 alkyl group refers to an alkyl group having 1 to 6 carbon atoms in total, for example, it can be one of methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl and n-hexyl.

[0031] In some preferred embodiments of the present invention, i is an integer from 1 to 5, that is, silicon and alkenyl (-CH2=CH 2- ) is 1-5, for example, 1, 2, 3, 4 or 5.

[0032] In some preferred embodiments of the present invention, R1, R2 and R3 are independently selected from methyl, ethyl, n-propyl or isopropyl. In the present invention, R1, R2 and R3 may be the same or different. Preferably, R1, R2 and R3 are the same.

[0033] The present invention adds a specific silanization agent (a compound shown in formula (I)) to the titanium silicalite sol, and through the dispersion force between the alkenyl groups in the silanization agent and the attraction between molecules, a titanium silicalite molecular sieve with a multi-level pore structure can be prepared. The multi-level pore structure is not only conducive to the diffusion of substances, but also accelerates the mass transfer capacity and improves the catalytic performance of the catalyst in the propylene gas phase epoxidation reaction; it can also improve the coke capacity of the catalyst and extend the service life of the catalyst.

[0034] According to the present invention, if the amount of the silanization agent (the compound shown in formula (I)) is too high, the crystallization performance of the titanium silical sol will deteriorate; and if the amount of the silanization agent (the compound shown in formula (I)) is too low, the pore size of the obtained titanium silicalite molecular sieve will be reduced, affecting mass transfer; under preferred conditions, in step (1), the silicon source is calculated as SiO2, and the molar ratio of the silicon source to the compound shown in formula (I) is 1: (0.01-0.3), preferably 1: (0.01-0.2); more preferably 1: (0.05-0.2).

[0035] In some preferred embodiments of the present invention, the silicon source is calculated as SiO2, the alkaline template is calculated as N when it contains nitrogen, and the alkaline template is calculated as OH when it does not contain nitrogen. - The molar ratio of the silicon source, the alkaline template and water is 1:(0.05-0.4):(5-40); preferably 1:(0.1-0.3):(5-25).

[0036] According to the present invention, the type of the silicon source can be selected within a wide range. Under preferred conditions, the silicon source is selected from at least one of methyl orthosilicate, ethyl orthosilicate, propyl orthosilicate, butyl orthosilicate, silica gel, white carbon black and silica sol.

[0037] According to the present invention, the type of the alkaline template agent can be selected within a wide range. Under preferred conditions, the alkaline template agent is selected from at least one of quaternary ammonium bases, aliphatic amines and aliphatic alcohol amines, preferably at least one of tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide and tetrabutylammonium hydroxide.

[0038] In some preferred embodiments of the present invention, the silicon source is calculated as SiO2, the titanium source is calculated as TiO2, and the molar ratio of the silicon source to the titanium source is 1:(0.001-0.04), preferably 1:(0.005-0.025), and more preferably 1:(0.01-0.02).

[0039] According to the present invention, the type of the titanium source can be selected within a wide range. Under preferred conditions, the titanium source is selected from an organic titanium source and / or an inorganic titanium source; further preferably, the titanium source is selected from at least one of titanium tetrachloride, titanium sulfate, titanium nitrate, tetraethyl titanate, tetrapropyl titanate and tetrabutyl titanate.

[0040] In a preferred embodiment of the present invention, step (1) further comprises: mixing the silicon source, the alkaline template and water, and performing a first stirring at room temperature for 0.1-2 hours, then adding the titanium source during the stirring process, and performing a second stirring for 0.5-6 hours to obtain titanium silicalose. Under preferred conditions, the second stirring time is 0.5-3 hours, more preferably 2-3 hours.

[0041] According to the present invention, under preferred conditions, step (1) further comprises: driving out alcohol after the mixing; driving out alcohol can remove alcohol generated by hydrolysis of silicon source and titanium source, and in the present invention, preferably azeotropic distillation is used to remove alcohol generated in the system, and water lost by azeotropic distillation is supplemented during the driving out alcohol process to ensure that the ratio of each substance in the titanium silica sol meets the above requirements; preferably, the conditions for driving out alcohol include: temperature of 30-100°C and time of 2-10h; more preferably: temperature of 40-90°C and time of 4-10h, and further preferably, the conditions for driving out alcohol include: temperature of 60-70°C and time of 6-8h.

[0042] According to the present invention, under preferred conditions, step (1) further comprises: adding the compound represented by formula (I) to the titanium silical sol and performing a third stirring for 0.1-24 hours, preferably the third stirring time is 0.5-10 hours, more preferably 2-4 hours.

[0043] According to the present invention, under preferred conditions, in step (2), the conditions for hydrothermal crystallization include: heating the mixture to 50-200°C within 0.1-3h, and then performing hydrothermal crystallization at 50-200°C for 10-100h; preferably, performing hydrothermal crystallization at a temperature of 100-200°C for 20-80h; further preferably, the heating time is 0.3-0.6h; more preferably, the conditions for hydrothermal crystallization include: a temperature of 150-180°C and a time of 20-60h.

[0044] The present invention has no particular limitation on the pressure of hydrothermal crystallization, which may be the autogenous pressure of the crystallization system.

[0045] According to the present invention, under preferred conditions, the method further comprises: washing, filtering and drying the product obtained by hydrothermal crystallization; wherein the washing, filtering and drying processes can be known to those skilled in the art. Exemplarily, the washing temperature can be 20-50°C, the washing solvent can be water, and the amount of the washing solvent is 1-20 times the mass of the crystallized product; the drying conditions can be: the temperature is 40-150°C and the time is 0.5-24h.

[0046] In some preferred embodiments of the present invention, the calcination conditions include: a temperature of 400-800° C. and a time of 1-15 h; preferably a temperature of 500-600° C. and a time of 4-8 h.

[0047] The titanium silicalite molecular sieve prepared by the above method has a certain proportion of mesoporous channels, which is not only conducive to the diffusion of substances, accelerates the mass transfer capacity, and improves the catalytic performance of the catalyst in the propylene gas phase epoxidation reaction; it can also improve the coke holding capacity, thereby extending the service life of the catalyst.

[0048] The second aspect of the present invention provides a propylene gas-phase epoxidation catalyst prepared according to the method described in the first aspect.

[0049] Preferably, the catalyst comprises titanium silicate molecular sieve and gold nanoparticles supported on the titanium silicate molecular sieve.

[0050] According to the present invention, preferably, based on the total amount of the gold nanoparticles, the content of the gold nanoparticles with a particle size of 1-2 nm is greater than 40%.

[0051] According to the present invention, further preferably, the weight content of gold in the propylene gas-phase epoxidation catalyst is 0.04-1 wt %, based on the total amount of the propylene gas-phase epoxidation catalyst.

[0052] The third aspect of the present invention provides a method for gas phase epoxidation of propylene, comprising: mixing propylene, hydrogen, oxygen and nitrogen for reaction in the presence of a catalyst, wherein the catalyst comprises the gas phase epoxidation catalyst for propylene described in the second aspect.

[0053] Under the preferred conditions, the reaction conditions include: temperature of 120-200°C, space velocity of 3-10 L·h -1 ·g -1 ; Further preferably, the reaction conditions also include: the volume ratio of propylene, hydrogen, oxygen and nitrogen is 1: (0.8-1.2): (0.8-1.2): (5-10).

[0054] According to a particularly preferred embodiment of the present invention, the method for preparing a propylene gas phase epoxidation catalyst comprises:

[0055] 1) Preparation of titanium silicate molecular sieve:

[0056] A silicon source, an alkaline template and water are mixed in a molar ratio of 1:(0.1-0.3):(5-25), and then a first stirring is performed at room temperature for 0.1-2 hours. Then, a titanium source is added during the stirring process, and a second stirring is performed for 2-3 hours to obtain a mixed system; wherein the molar ratio of the silicon source to the titanium source is 1:(0.005-0.025); then, the mixed system is subjected to alcoholization to obtain titanium silicalite, and the alcoholization temperature is 60-70°C for 6-8 hours; then, a compound represented by formula (I) is added to the titanium silicalite and a third stirring is performed for 2-4 hours, and the obtained mixture is subjected to hydrothermal crystallization and calcination to obtain a titanium silicalite molecular sieve;

[0057] The molar ratio of the silicon source to the compound represented by formula (I) is 1:(0.01-0.2), and the crystallization conditions are: heating the mixture to 150-180° C. within 0.3-0.6 h, and then performing hydrothermal crystallization at 150-180° C. for 20-60 h;

[0058]

[0059] Formula (I)

[0060] wherein i is an integer of 1-5; R1, R2 and R3 are the same; R1, R2 and R3 are selected from methyl, ethyl, n-propyl or isopropyl;

[0061] 2) Preparation of catalyst: under the conditions of pH 6-10 and temperature 40-70°C, the titanium silicon molecular sieve and the boron-containing auxiliary agent are added to a 0.005-0.5 mol / L chloroauric acid aqueous solution, mixed and stirred for 5-36 hours to obtain a suspension, wherein the boron-containing auxiliary agent is selected from at least one of boric acid, borax and sodium metaborate; the weight ratio of the chloroauric acid aqueous solution to the titanium silicon molecular sieve is 100:(0.04-1) in terms of gold; the molar ratio of the boron-containing auxiliary agent to the chloroauric acid aqueous solution is (1-7):1; in a hydrogen atmosphere, the filter residue obtained by filtering the suspension is roasted at 150-250°C for 3-5 hours to obtain a propylene gas phase epoxidation catalyst.

[0062] The present invention will be described in detail below by way of examples. In the following examples, room temperature refers to 25±5°C.

[0063] The content of gold in the catalyst with a particle size of 1-2 nm was obtained by TEM testing.

[0064] In the following examples, the silanization agents used are shown in Table 1.

[0065] Table 1

[0066]

[0067]

[0068] Preparation Example 1

[0069] (1) methyl orthosilicate, tetrapropylammonium hydroxide and water are first stirred at room temperature for 0.5 h, and tetraethyl titanate is added during the stirring process, and a second stirring is performed for 2.5 h to obtain a mixed system; wherein methyl orthosilicate is calculated as SiO2, tetrapropylammonium hydroxide is calculated as N, and tetraethyl titanate is calculated as TiO2, and the molar ratio of methyl orthosilicate, tetrapropylammonium hydroxide, water and tetraethyl titanate is 1:0.1:20:0.015;

[0070] Then, the mixed system was subjected to alcoholization at 70°C for 7 hours to obtain titanium silicalose;

[0071] (2) adding compound 1 (the structural formula is shown in Table 1) to the titanium silicalite, and stirring for a third time at room temperature for 2 hours to obtain a mixture, wherein the molar ratio of compound (1) to tetramethyl silicate is 0.15:1;

[0072] (3) heating the mixture to 170° C. within 0.5 h, and performing hydrothermal crystallization at 170° C. for 48 h to obtain a crystallized product;

[0073] The crystallized product was sequentially washed with water, filtered, and dried at 120 °C for 2 h;

[0074] The dried product was calcined at 550°C for 6 hours to obtain titanium silicon molecular sieve TS-1.

[0075] Preparation Example 2-15

[0076] According to the method of Preparation Example 1, titanium silicalite molecular sieves TS-2 to TS-15 were obtained respectively, and their proportions and synthesis conditions are shown in Table 2.

[0077] Table 2

[0078]

[0079] Note: 1- molar ratio; 2- molar ratio; 3- molar ratio

[0080] Examples 1-6

[0081] 100 mL of deionized water was added to 20.8 mL of chloroauric acid aqueous solution (0.01 mol / L) for dilution, and then the titanium silicon molecular sieve TS-1 and the boron-containing auxiliary agent obtained in Preparation Example 1 were added. After stirring for 0.3 h, the pH value was adjusted to 7, and then stirred at 60 ° C for 12 h to obtain a suspension. The residue obtained by filtering the suspension was washed, and then vacuum dried at 30 ° C for 10 h, and then calcined at 220 ° C for 3 h in a hydrogen atmosphere. The amount of each substance and the reaction conditions are shown in Table 3 to obtain catalysts Au / TS-1 to Au / TS-6.

[0082] Examples 7-11 and Comparative Examples 1-11

[0083] The method of Example 1 was followed, except that the amounts of each substance used and the reaction conditions were as shown in Table 3.

[0084] Table 3

[0085]

[0086] Note: * refers to the weight ratio of titanium silicon molecular sieve to the chloroauric acid aqueous solution in terms of gold;

[0087] ** Refers to the molar ratio of the additive to the chloroauric acid in the chloroauric acid aqueous solution;

[0088] ***1-2nm: The content of gold with a particle size of 1-2nm, based on the total amount of gold in the catalyst.

[0089] Test Case

[0090] Au / TS-1 to Au / TS-22 were used as catalysts, respectively, and the catalysts were loaded into a fixed bed reactor at normal pressure, and then propylene, hydrogen, oxygen and nitrogen were introduced respectively to start the reaction, and the volume ratio of propylene: hydrogen: oxygen: nitrogen was 1:1:1:7, the reaction temperature was 160°C, and the products were analyzed online after the reaction time of 1h, 10h, 50h, 100h and 200h, respectively; wherein the catalyst loading amount was 0.36g, and the space velocity was 8000mL·h -1 ·g -1 cat The catalytic reaction results are shown in Table 4.

[0091] In the present invention, gas chromatography is used to analyze the reactants and products in the evaluation system, wherein the gas chromatography analysis conditions are: Agilent-6890 chromatograph, molecular sieve 5A and PoraBOND U chromatographic columns, FID and TCD detectors.

[0092] Propylene conversion % = (moles of propylene in the feedstock - moles of propylene in the product) / moles of propylene in the feedstock × 100%

[0093] Propylene oxide selectivity % = moles of propylene oxide in the product / (moles of propylene in the feed - moles of propylene in the product) × 100%

[0094] Table 4

[0095]

[0096] Note: *Propylene refers to the conversion rate of propylene, and *Po refers to the selectivity of propylene oxide.

[0097] It can be seen from the results in Table 4 that the propylene gas-phase epoxidation catalyst prepared in the embodiment of the present invention has high catalytic activity and service life. When used in the propylene gas-phase epoxidation reaction, the selectivity of propylene oxide is as high as 95.5%, and after 200 hours of reaction, the selectivity of propylene oxide is still as high as 94.9%.

[0098] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for preparing a catalyst for gas phase epoxidation of propylene, characterized in that: The method comprises: (1) Mixing titanium silicon molecular sieve, boron-containing additive and chloroauric acid aqueous solution under the condition of pH 6-10, stirring to obtain a suspension; (2) calcining the filter residue obtained by filtering the suspension in a hydrogen atmosphere to obtain a propylene gas-phase epoxidation catalyst; Wherein, the boron-containing auxiliary agent is selected from at least one of boric acid, borax and sodium metaborate; The method also includes the preparation of titanium silicon molecular sieve, and the preparation method of titanium silicon molecular sieve includes: The silicon source, the alkaline template, the titanium source and water are uniformly mixed to obtain a titanium silical sol; then the compound represented by formula (I) is added to the titanium silical sol, and the obtained mixture is hydrothermally crystallized and calcined; Formula (I) Wherein, i is an integer of 1-10; R1, R2 and R3 are each independently selected from a C1-C6 alkyl group.

2. The method according to claim 1, wherein: The weight ratio of the chloroauric acid aqueous solution to the chloroauric acid aqueous solution is 100:(0.04-1) based on gold. And / or, the molar ratio of the boron-containing auxiliary agent to the aqueous solution of chloroauric acid is (1-10):

1.

3. The method according to claim 1 or 2, wherein: The molar ratio of the boron-containing auxiliary agent to the aqueous solution of chloroauric acid is (1-7):

1.

4. The method according to claim 1 or 2, wherein: The concentration of chloroauric acid in the chloroauric acid aqueous solution is 0.005-0.5 mol / L.

5. The method according to claim 1 or 2, wherein: In step (1), the stirring conditions include: temperature of 40-70° C. and time of 5-36 h.

6. The method according to claim 1 or 2, wherein: In step (2), the calcination conditions include: temperature of 100-350°C and time of 2-8h.

7. The method according to claim 1 or 2, wherein: In step (2), the calcination conditions include: temperature of 150-250° C. and time of 3-5 h.

8. The method according to claim 1 or 2, wherein: i is an integer from 1 to 5; And / or, R1, R2 and R3 are each independently selected from methyl, ethyl, n-propyl or isopropyl.

9. The method according to claim 1 or 2, wherein: The silicon source is calculated as SiO2, the alkaline template is calculated as N when it contains nitrogen, and as OH when it does not contain nitrogen. - The titanium source is calculated as TiO2, and the molar ratio of the silicon source to the compound represented by formula (I) is 1: (0.01-0.3); and / or, the molar ratio of the silicon source, the alkaline template and water is 1:(0.05-0.4):(5-40); And / or, the molar ratio of the silicon source to the titanium source is 1:(0.001-0.04).

10. The method according to claim 1 or 2, wherein: The silicon source is calculated as SiO2, the alkaline template is calculated as N when it contains nitrogen, and as OH when it does not contain nitrogen. - The titanium source is calculated as TiO2, and the molar ratio of the silicon source to the compound represented by formula (I) is 1: (0.01-0.2); and / or, the molar ratio of the silicon source, the alkaline template and water is 1:(0.1-0.3):(5-25); And / or, the molar ratio of the silicon source to the titanium source is 1:(0.005-0.025).

11. The method according to claim 1 or 2, wherein: The conditions of the hydrothermal crystallization include: heating the mixture to 50-200° C. within 0.1-3 h, and then crystallizing at 50-200° C. for 10-100 h; And / or, the calcination conditions include: temperature of 400-800° C. and time of 1-15 h.

12. The method according to claim 1 or 2, wherein: The conditions of the hydrothermal crystallization include: performing crystallization at a temperature of 100-200° C. for 20-80 hours.

13. A catalyst for gas phase epoxidation of propylene, characterized in that: Prepared according to the method according to any one of claims 1 to 12.

14. The catalyst according to claim 13, wherein The catalyst comprises titanium silicon molecular sieve and gold nanoparticles supported on the titanium silicon molecular sieve; Based on the total amount of gold nanoparticles in the catalyst, the content of gold with a particle size of 1-2 nm is greater than 40wt%; And / or, based on the total amount of the catalyst, the weight content of gold in the catalyst is 0.04-1wt%.

15. A method for gas phase epoxidation of propylene, characterized in that: The method comprises: mixing propylene, hydrogen, oxygen and nitrogen for reaction in the presence of a catalyst, wherein the catalyst comprises the catalyst for gas-phase epoxidation of propylene according to claim 13 or 14.

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