A multi-level hole TS-1@WO x Composite catalyst and preparation method thereof, method for synthesizing 1,2-epoxyhexane

Abstract

The present invention discloses a hierarchical pore TS-1@WO x composite catalyst and its preparation method, and a method for synthesizing 1,2-epoxyhexane, which relates to the technical field of catalytic material preparation and application, including: first preparing hierarchical pore TS-1 molecular sieve by an etching method, and then preparing hierarchical pore TS-1@WO x composite catalyst by impregnation-recrystallization method using the hierarchical pore TS-1 molecular sieve and metal tungstate solution; adding 1-hexene and hydrogen peroxide solution into an organic solvent, adding the catalyst for reaction to obtain 1,2-epoxyhexane. The beneficial effects of the present invention are that the hierarchical pore TS-1@WO x composite catalyst has a high specific surface area and hierarchical pore structure, which can effectively promote the mass transfer and diffusion of reactant and product molecules in the pores; it also has dual catalytic active sites of titanium silicate molecular sieve and metal tungsten oxide, and has a synergistic catalytic effect, which can improve the conversion rate of 1-hexene and the selectivity and yield of 1,2-epoxyhexane.

Description

Technical Field

[0001] The present invention belongs to the field of catalytic material preparation and application, and specifically relates to a multi-level pore TS-1@WO x A composite catalyst and a preparation method thereof, and a method for synthesizing 1,2-epoxyhexane. Background Art

[0002] 1,2-Epoxyhexane, also known as butyl oxirane, is an organic synthesis intermediate with high added value. 1,2-Epoxyhexane can be mainly used to synthesize polyether polyols, nonionic surfactants and demulsifiers. Among them, polyether polyols are important raw materials for synthesizing polyurethane foams, thermal insulation materials, elastomers, adhesives and coatings, while various nonionic surfactants can be widely used in petroleum, chemical, pesticide, daily chemical, textile and other industries. 1,2-Epoxyhexane is usually prepared by the epoxidation reaction of 1-hexene, but due to the electron-deficient characteristics of the terminal olefin, its epoxidation reaction is challenging. At present, the industrial production of 1,2-epoxyhexane mostly adopts the halogen alcohol method and organic peracid oxidation method. In the early industrial preparation of epoxides, the halogen alcohol method was widely used, and the process conditions were mature. However, hypochlorous acid can cause equipment corrosion and produce a large amount of chlorine-containing wastewater during the production process, with low atom economy and serious environmental pollution. It is currently being gradually eliminated. The separation cost of the organic peroxy acid method is high, polluting the environment, and its chemical structure is unstable and easy to decompose. In practical applications, hydrogen peroxide is usually required to generate peroxy acid in situ, but at the same time, 1,2-epoxyhexane is also easily deeply oxidized to 1,2-hexanediol. In summary, it is imperative to develop green and environmentally friendly epoxidation catalysts suitable for long-chain terminal olefins.

[0003] Titanium silicate (TS-1) catalyst is a catalyst that has been studied more frequently for olefin epoxidation reactions. It has excellent catalytic performance for olefin epoxidation reactions using dilute H2O2 as an oxidant. This unique selective oxidation performance is widely believed to be due to the isolated tetracoordinated titanium and hydrophobic outer surface of TS-1. However, the micropore size of traditional titanium silicate (TS-1) is small, which makes it difficult for reactant and product molecules to diffuse in a single and narrow channel and unable to efficiently contact the titanium active sites, greatly limiting its catalytic performance. In addition, metal oxides have attracted much attention as heterogeneous catalysts in the selective oxidation of olefins. Researchers have long begun to study metal oxides or supported metal oxides as epoxidation catalysts. Among them, nano-metal oxides have become a research hotspot in recent years due to their advantages such as many active sites and large specific surface area. For example, WO XIt is an effective metal oxide catalyst for catalyzing the epoxidation of 1-hexene. It has the characteristics of high thermal stability, economy, safety and pollution-free, and is widely used in various processes. However, due to its poor activity, it still faces challenges in the selective oxidation of linear terminal olefins to epoxides. The aggregation and reorganization of metal oxides are still defects that limit their application. At present, the research on this part of catalysts mainly focuses on the regulation of microstructure and morphology. Summary of the invention

[0004] The purpose of the present invention is to solve at least one of the technical problems existing in the prior art and provide a multi-level hole TS-1@WO x Composite catalyst and preparation method thereof, method for synthesizing 1,2-epoxyhexane. Aiming at the effective epoxidation of low-activity 1-hexene, the present invention develops a simple, low-cost and green titanium silicon molecular sieve@metal oxide composite catalyst for effective epoxidation of long straight-chain terminal olefins. The catalyst confines metal nanoparticles within TS-1 molecular sieve crystals, successfully combining the advantages of multi-level pore molecular sieve catalysts with metal oxides. The molecular sieve pores can serve as diffusion channels, providing shape selectivity and sintering resistance, while the highly dispersed metal oxides provide significant catalytic activity. The present invention combines titanium silicon molecular sieves to solve the problem that low-concentration hydrogen peroxide is difficult to achieve olefin epoxidation reaction, significantly improves the catalytic performance of TS-1 molecular sieves and metal oxides, the reaction rate of the target reaction and the yield of the target product, and simultaneously realizes the green and sustainable production of 1,2-epoxyhexane, and effectively increases the yield of 1,2-epoxyhexane.

[0005] The technical solution of the present invention is as follows:

[0006] The first aspect of the present invention provides a multi-level hole TS-1@WO x The preparation method of the composite catalyst comprises: firstly preparing a multi-level porous TS-1 molecular sieve by an etching method, then impregnating and recrystallizing the multi-level porous TS-1 molecular sieve with a metal tungsten salt solution to prepare a multi-level porous TS-1@WO x Composite catalyst.

[0007] Preferably, the method specifically comprises the following steps:

[0008] (1) Etching nano TS-1 molecular sieve with TPAOH aqueous solution to obtain multi-level pore TS-1 molecular sieve;

[0009] (2) dispersing the multi-level pore TS-1 molecular sieve and tungsten hexachloride powder prepared in (1) in a solvent, and immersing them for 20 to 28 hours to obtain a multi-level pore TS-1 molecular sieve loaded with tungsten oxide metal particles;

[0010] (3) The hierarchical TS-1 molecular sieve loaded with tungsten oxide metal particles prepared in (2) was fully mixed with the TPAOH aqueous solution and then transferred to a closed reactor to prepare the hierarchical TS-1@WO by recrystallization. x Composite catalyst.

[0011] The multi-level pore TS-1@WO prepared according to the above steps x Composite catalysts have good advantages and application prospects. On the one hand, after the template etching treatment, many empty nests are etched inside the crystal, which significantly increases the pore size and the distribution of titanium active sites, thereby forming a multi-level pore system with micro-mesopores to improve its molecular mass transfer and diffusion rate; on the other hand, metal particles are loaded on the surface of the molecular sieve and encapsulated into the empty nests and pores inside the molecular sieve crystal by the impregnation-recrystallization method, thereby forming the catalytic active sites of metal tungsten oxide, further enhancing its catalytic reaction efficiency; therefore, the multi-level pore TS-1@WO x The composite catalyst not only has a multi-level pore structure, but also has dual catalytic active sites of titanium silicon molecular sieve and metal tungsten oxide, thus having a synergistic catalytic effect and greatly enhancing the epoxidation efficiency of 1-hexene.

[0012] Preferably, in step (1), the ratio of the volume of the TPAOH aqueous solution to the mass of the TS-1 molecular sieve is 20-100 ml: 1 g; and the etching conditions are 40-100 °C and 4-16 h.

[0013] Preferably, in step (2): the mass ratio of the multi-level pore TS-1 molecular sieve to the tungsten hexachloride powder is 1:0.01-1:0.2; the volume ratio of the solvent to the total mass of the multi-level pore TS-1 molecular sieve and the tungsten hexachloride powder is 20-100 ml: 1 g.

[0014] Preferably, in step (3): the ratio of the mass of the multi-level pore TS-1 molecular sieve loaded with tungsten oxide metal particles to the volume of the TPAOH aqueous solution is 1 g: 10-100 ml; the crystallization temperature of the recrystallization method is 120-180°C, and the crystallization time is 1-10 h;

[0015] The second aspect of the present invention provides a multi-level hole TS-1@WO x The composite catalyst is obtained by the preparation method described in the claims.

[0016] Among them, WO x is tungsten oxide, and x can be 3.

[0017] Multi-level pore TS-1@WO prepared by the present invention x The composite catalyst not only has a multi-level pore structure, but also has dual catalytic active sites of titanium silicon molecular sieve and metal tungsten oxide.

[0018] The third aspect of the present invention provides a method using the multi-level hole TS-1@WO x A method for producing 1,2-epoxyhexane with a composite catalyst comprises: adding 1-hexene and a hydrogen peroxide solution into an organic solvent, adding the multi-level porous TS-1@WO x , mix and heat to react to obtain 1,2-epoxyhexane.

[0019] Multi-level pore TS-1@WO prepared by the present invention x When the composite catalyst catalyzes hydrogen peroxide and 1-hexene to synthesize 1,2-epoxyhexane, it not only solves the problems of low molecular mass transfer and diffusion efficiency and waste residue emission pollution, but also effectively enhances the reaction efficiency of 1-hexene epoxidation to synthesize 1,2-epoxyhexane, especially in the case of high 1-hexene conversion rate, it can also ensure high 1,2-epoxyhexane selectivity. It is a truly green process for the production of 1,2-epoxyhexane, and is very likely to replace the traditional 1,2-epoxyhexane production process, with good application prospects.

[0020] Preferably, the molar ratio of 1-hexene to hydrogen peroxide solution is 1:1, and the multi-level pore TS-1@WO x The addition amount of the composite catalyst is 1-10 wt% of the reaction liquid.

[0021] Preferably, the reaction temperature is 40-80 ° C, and the reaction time is 2-4 hours.

[0022] Preferably, the organic solvent is one of methanol, acetonitrile and a mixed solvent of methanol + acetonitrile; the volume ratio of 1-hexene to the organic solvent is 1:10-1:30; the volume ratio of methanol to acetonitrile in the mixed solvent of methanol + acetonitrile is 1:1-3.

[0023] The present invention has at least one of the following beneficial effects:

[0024] 1. The present invention realizes the construction of multi-level pore structure and the successful loading and encapsulation of metal oxides by a simple etching-impregnation-recrystallization method, that is, the preparation of multi-level pore TS-1@WO x Compared with the methods in the prior art, the present invention etches many empty nests inside the crystal after the template etching treatment, WO xMetal particles are encapsulated in it. This unique structure ensures a shorter diffusion path length, high catalytic activity and high selectivity, significantly increases the pore size and the distribution of active sites of titanium, thereby forming a multi-level pore system with coexisting micro-mesopores to improve its molecular mass transfer diffusion rate; on the other hand, the metal particles are loaded on the surface of the molecular sieve and encapsulated into the empty nests and pores inside the molecular sieve crystals through the impregnation-recrystallization method, thereby forming catalytic active sites of metal tungsten oxide, further enhancing its catalytic reaction efficiency.

[0025] 2. Multi-level pore TS-1@WO of the present invention x The composite catalyst not only has a high specific surface area and a multi-level pore structure, which can effectively promote the mass transfer and diffusion of reactant and product molecules in the pores; it also has dual catalytic active sites of titanium silicalite and metal tungsten oxide, thus having a synergistic catalytic effect, which can effectively solve the problem of low efficiency of 1-hexene epoxidation reaction catalyzed by titanium silicalite, and significantly improve the conversion rate of 1-hexene and the selectivity and yield of 1,2-epoxyhexane. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The multi-level hole TS-1@WO in the embodiment x Schematic diagram of the preparation process of the composite catalyst;

[0027] Figure 2 The multi-level pore TS-1@WO in Example 1 x SEM photos and TEM images of the composite catalyst;

[0028] Figure 3 The multi-level pore TS-1@WO in Example 1 x HAADF and mapping images of composite catalysts;

[0029] Figure 4 The multi-level pore TS-1@WO in Example 1 x N2 adsorption-desorption curve and pore size distribution diagram of the composite catalyst;

[0030] Figure 5 The multi-level pore TS-1@WO in Example 1 x XRD and XPS spectra of the composite catalyst. DETAILED DESCRIPTION

[0031] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0032] The present invention is further described in detail below with specific examples, but the present invention is not limited to the following specific examples.

[0033] Example 1

[0034] like Figure 1 As shown, in a preferred embodiment of the present invention, a multi-level porous TS-1 molecular sieve is prepared by a dissolution method, and then the multi-level porous TS-1 molecular sieve and a metal tungsten salt solution are impregnated and recrystallized to prepare a multi-level porous TS-1@WOx composite catalyst. The steps are as follows:

[0035] The TS-1 molecular sieve and TPAOH solution were fully mixed at a ratio of 40 ml / g, stirred at 80 ° C for 8 hours, cooled to room temperature, centrifuged and dried for 10 hours to obtain a multi-level pore TS-1 molecular sieve. An appropriate amount of tungsten hexachloride was weighed and added to anhydrous ethanol, and the tungsten hexachloride was completely dissolved by oscillation and ultrasound until the solution was bright yellow. The mass ratio of the multi-level pore TS-1 molecular sieve to the tungsten hexachloride powder was 1:0.02, and the volume of the ethanol solvent was 40 ml / g. The multi-level pore TS-1 molecular sieve and the tungsten hexachloride powder were immersed and stirred at room temperature for 24 hours, and the multi-level pore TS-1 molecular sieve loaded with tungsten oxide was dried at room temperature after centrifugation and collection; finally, the obtained multi-level pore TS-1 molecular sieve loaded with tungsten oxide was added to the TPAOH solution at a ratio of 10 ml / g, fully mixed, and then transferred into a reactor for recrystallization at 170 ° C for 2 hours. After complete crystallization, the multi-level pore TS-1@WO was obtained after washing, centrifugation, and drying. x Composite catalyst, denoted as TS-1@WO x -1.

[0036] The multi-level pore TS-1@WO prepared in the above embodiment x The morphology and structure of the composite catalyst are Figure 2 , Figure 2 a and b in the figure are multi-level holes TS-1@WO x SEM image of the composite catalyst; Figure 2 Figures c and d are TEM images of the multi-level pore TS-1@WOx composite catalyst; as shown in the figure, the composite catalyst has a typical elliptical shape, clear outline, complete structure, and a size of about 300-500nm. Obvious small holes can be observed on the surface of the crystal, indicating that interconnected channels have been formed inside the crystal. In addition, the TEM image can more intuitively observe the large and small hollow nests etched inside the crystal, and some of the hollow nests have obvious metal oxides encapsulated inside.

[0037] Figure 3 Multi-level hole TS-1@WO xThe HAADF and mapping images of the composite catalyst show more obvious observation of the metal particles encapsulated in the hollow nests of the crystals under high-angle annular dark field. In the given mapping image, Si and Ti elements are densely and evenly distributed on the crystal surface, and W element is also detected, indicating the successful loading and encapsulation of metal oxides, which increases the Ti active sites and metal catalytic sites.

[0038] Figure 4 Multi-level hole TS-1@WO x N2 adsorption-desorption curve and pore size distribution diagram of the composite catalyst. As shown in the figure: Figure 4 The isothermal adsorption curve of a is biased toward the y-axis in the low specific pressure region, indicating the existence of micropores, and an obvious hysteresis loop appears in the high specific pressure region, indicating the existence of mesopores / macropores; Figure 4 The pore size distribution curve of b shows that the pore sizes are concentrated around 5nm and 40-50nm.

[0039] Multi-stage hole TS-1@WO x The XRD and XPS spectra of the composite catalyst are shown in Figure 5 As shown, Figure 5 a is multi-level hole TS-1@WO x XRD pattern of the composite catalyst; Figure 4 b is multi-level hole TS-1@WO x XPS spectrum of the composite catalyst; as shown in the figure: multi-level pore TS-1@WO x The composite catalyst exhibits the characteristic peaks of typical MFI molecular sieves, which are consistent with the characteristic peak intensity of standard MFI molecular sieves. In addition, characteristic peaks belonging to tungsten oxides also appear at 2θ of 24°, 34° and 55.3°. In the fine XPS spectrum of metal W, the characteristic peaks at 38.3 and 36.8 eV belong to tungsten oxides of different valence states, indicating the presence of tungsten oxides.

[0040] TS-1@WO x TS-1@WO catalyzes the preparation of 1,2-epoxyhexane by 1-hexene ring. 1-Hexene and hydrogen peroxide solution were added into a reactor containing acetonitrile solvent in a molar ratio of 1:1 and reacted at 60 °C for 4 h. x The mass percentage of the composite catalyst to the reaction liquid was 5 wt %, and the volume ratio of the reaction liquid to the acetonitrile solvent was 1:20. After the reaction was complete, the multi-level porous TS-1@WO was recovered by filtration. x Composite catalyst, gas chromatography analysis of the reaction liquid composition after separation, under this condition, the 1-hexene conversion rate is 93.07%, and the selectivity of 1,2-epoxyhexane is 96.30%.

[0041] Example 2

[0042] Multi-stage hole TS-1@WO x The difference between the preparation of the composite catalyst and Example 1 is that the ratio of TS-1 molecular sieve to TPAOH solution is changed to 25 ml / g, and the etching conditions are changed to 60 °C and 12 h to prepare the multi-level pore TS-1@WO x Composite catalyst, denoted as TS-1@WO x -2.

[0043] TS-1@WO x The process of TS-1@WO catalyzing 1-hexene ring to prepare 1,2-epoxyhexane is consistent with that in Example 1. x The catalytic performance of the -2 composite catalyst is as follows: the conversion rate of 1-hexene is 85.12%, and the selectivity of 1,2-epoxyhexane is 90.56%.

[0044] Example 3

[0045] Multi-stage hole TS-1@WO x The difference between the preparation of the composite catalyst and Example 1 is that the mass ratio of the multi-level pore TS-1 molecular sieve to the tungsten hexachloride powder is changed to 1:0.05; the volume of anhydrous ethanol and the ratio of the multi-level pore TS-1 molecular sieve to the tungsten hexachloride powder are changed to 60 ml / g, and the multi-level pore TS-1@WO is prepared. x Composite catalyst, denoted as TS-1@WO x -3.

[0046] TS-1@WO x The process of TS-1@WO catalyzing 1-hexene ring to prepare 1,2-epoxyhexane is consistent with that in Example 1. x The catalytic performance of the -3 composite catalyst is as follows: 1-hexene conversion rate is 85.12%, and the selectivity of 1,2-epoxyhexane is 90.56%.

[0047] Comparative Example 1

[0048] Comparative Example 1: Preparation of TS-1@WO by impregnation-recrystallization method x Composite catalyst.

[0049] Appropriate amounts of TS-1 molecular sieve and tungsten hexachloride were weighed and added to anhydrous ethanol. The tungsten hexachloride was completely dissolved by oscillation and ultrasound until the solution was bright yellow. The mass ratio of TS-1 molecular sieve to tungsten hexachloride powder was 1:0.05, and the volume of anhydrous ethanol solvent and the mass ratio of TS-1 molecular sieve to tungsten hexachloride powder were 40 ml / g. The mixture was stirred at room temperature for 24 h, and then dried at room temperature after centrifugation to obtain TS-1 molecular sieve loaded with tungsten oxide. Finally, the obtained TS-1 molecular sieve loaded with tungsten oxide was added to TPAOH solution at a ratio of 30 ml / g, mixed thoroughly, and then transferred into a reactor for recrystallization at 150°C for 4 h. After complete crystallization, the TS-1@WOx composite catalyst was obtained after washing, centrifugation, and drying, which was recorded as TS-1@WO x -4.

[0050] TS-1@WO x The process of TS-1@WO catalyzing 1-hexene ring to prepare 1,2-epoxyhexane is consistent with that in Example 1. x -4 catalyzed the epoxidation of 1-hexene. After 4 h of reaction at 60 °C, the 1-hexene conversion rate was 75.72% and the selectivity of 1,2-epoxyhexane was 93.22%.

[0051] Example 4

[0052] Provided is a multi-level pore TS-1@WO prepared using Example 1 x A method for synthesizing 1,2-epoxyhexane using a composite catalyst. The total mass of the reaction liquid is 30 g. According to the molar ratio of 1-hexene: hydrogen peroxide: methanol = 1:1:20, the corresponding masses of each substance are weighed into a reaction flask and mixed evenly, and then a multi-level porous TS-1@WOx composite catalyst accounting for 5 wt% of the total mass of the reaction liquid is added, and the reaction is carried out at a constant temperature of 60°C. After 4 hours of reaction, the conversion rate of 1-hexene is 90.65%, and the selectivity of 1,2-epoxyhexane is 96.10%.

[0053] Example 5

[0054] Provides a multi-level hole TS-1@WO x The method for synthesizing 1,2-epoxyhexane using a composite catalyst is different from that in Example 1 in that the reaction temperature of the TS-1 molecular sieve and the TPAOH solution is changed to 40°C, and after reacting for 4 hours, the conversion rate of 1-hexene is 48.57%, and the selectivity of 1,2-epoxyhexane is 90.09%.

[0055] Example 6

[0056] Provides a multi-level hole TS-1@WO xThe method for synthesizing 1,2-epoxyhexane using a composite catalyst is different from that in Example 4 in that methanol is replaced by methanol+acetonitrile, and the volume ratio of methanol:acetonitrile is 1:1. The reaction is carried out at a constant temperature of 60°C, and after 4 hours of reaction, the conversion rate of 1-hexene is 60.03%, and the selectivity of 1,2-epoxyhexane is 97.70%.

[0057] Example 7

[0058] Provides a multi-level hole TS-1@WO x The method for synthesizing 1,2-epoxyhexane using a composite catalyst is different from that in Example 4 in that methanol is replaced by methanol+acetonitrile, and the volume ratio of methanol:acetonitrile is 1:2. The reaction is carried out at a constant temperature of 60°C, and after 4 hours of reaction, the conversion rate of 1-hexene is 90.97%, and the selectivity of 1,2-epoxyhexane is 91.65%.

[0059] Example 8

[0060] Provides a multi-level hole TS-1@WO x The method for synthesizing 1,2-epoxyhexane with a composite catalyst is different from that in Example 4 in that: 5 wt% of the total mass of the reaction liquid is added to the multi-level porous TS-1@WO x The composite catalyst was changed to add 2.5wt% of the total mass of the reaction liquid multi-level porous TS-1@WO x Composite catalyst. The reaction was carried out at a constant temperature of 60°C. After 4 hours of reaction, the conversion rate of 1-hexene was 65.62%, and the selectivity of 1,2-epoxyhexane was 93.98%.

[0061] Comparative Example 2

[0062] Comparative Example 4, TS-1 molecular sieve was directly used as a catalyst to catalyze the epoxidation of 1-hexene to synthesize 1,2-epoxyhexane, that is, multi-level pore TS-1@WO x The composite catalyst was changed to TS-1 molecular sieve catalyst. The reaction was carried out at a constant temperature of 60°C. After 4 hours of reaction, the conversion rate of 1-hexene was 67.21%, and the selectivity of 1,2-epoxyhexane was 63.66%.

[0063] The 1-hexene epoxidation performance data of Examples 1 to 8 and Comparative Examples 1 to 2 are listed in Table 1.

[0064] Table 1 1-Hexene epoxidation performance data of Examples 1 to 8 and Comparative Example 2

[0065]

[0066] According to the comparison and analysis of the experimental results, the multi-level pore TS-1@WO prepared by the present invention can be seen xThe composite catalyst and the method for synthesizing 1,2-epoxyhexane can significantly enhance the performance and efficiency of the epoxidation reaction of 1-hexene. In Comparative Example 2, TS-1 molecular sieve raw powder is used as a catalyst, and the 1-hexene conversion rate and 1,2-epoxyhexane selectivity are greatly reduced compared with Examples 1 to 3. In Comparative Example 1, the TS-1 molecular sieve is not etched, that is, a multi-level porous TS-1 molecular sieve is not formed. Compared with Example 1, the 1-hexene conversion rate and 1,2-epoxyhexane selectivity are both reduced, which shows that whether the TS-1 molecular sieve is etched will also affect the 1-hexene conversion rate and 1,2-epoxyhexane selectivity. Therefore, in several examples of control variables, the multi-level porous TS-1@WO prepared by the dissolution-impregnation-recrystallization route of the present invention is x The composite catalyst (Example 1) has the highest catalytic performance: the conversion rate of 1-hexene reaches 93.07%, and the selectivity of 1,2-epoxyhexane reaches 96.30%.

[0067] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A multi-level hole TS-1@WO x The method for preparing a composite catalyst is characterized in that: The following steps are involved: (1) Etching nano TS-1 molecular sieve with TPAOH aqueous solution to obtain multi-level pore TS-1 molecular sieve; (2) dispersing the hierarchical TS-1 molecular sieve and tungsten hexachloride powder prepared in (1) in a solvent and immersing them for 20 to 28 hours to obtain a hierarchical TS-1 molecular sieve loaded with tungsten oxide metal particles; (3) The hierarchical TS-1 molecular sieve loaded with tungsten oxide metal particles prepared in (2) was fully mixed with the TPAOH aqueous solution and then transferred to a closed reactor to prepare the hierarchical TS-1@WO by recrystallization. x Composite catalyst; In step (1): the volume ratio of the TPAOH aqueous solution to the mass of the TS-1 molecular sieve is 20-100 mL: 1 g; the etching conditions are 40-100 °C and 4-16 h.

2. The multi-level hole TS-1@WO according to claim 1 x The method for preparing a composite catalyst is characterized in that: In step (2), the mass ratio of the multi-level pore TS-1 molecular sieve to the tungsten hexachloride powder is 1:0.01-1:0.2; the volume ratio of the solvent to the total mass of the multi-level pore TS-1 molecular sieve and the tungsten hexachloride powder is 20-100 mL: 1 g.

3. The multi-level hole TS-1@WO according to claim 1 x The method for preparing a composite catalyst is characterized in that: In step (3): the ratio of the mass of the multi-level porous TS-1 molecular sieve loaded with tungsten oxide metal particles to the volume of the TPAOH aqueous solution is 1 g: 10-100 mL; the crystallization temperature of the recrystallization method is 120-180°C, and the crystallization time is 1-10 h.

4. A multi-level hole TS-1@WO x The composite catalyst is characterized in that The method is obtained by the preparation method described in any one of claims 1 to 3.

5. A method using the multi-level hole TS-1@WO as claimed in claim 4 x A method for producing 1,2-epoxyhexane using a composite catalyst, characterized in that: include: 1-Hexene and hydrogen peroxide solution were added to the organic solvent, and the multi-level porous TS-1@WO x The composite catalyst is mixed and heated to react to obtain 1,2-epoxyhexane.

6. The method according to claim 5, characterized in that The molar ratio of 1-hexene to hydrogen peroxide solution is 1:1, and the multi-level pore TS-1@WO x The addition amount of the composite catalyst is 1-10 wt% of the reaction liquid.

7. The method according to claim 5, characterized in that The reaction temperature is 40-80°C and the reaction time is 2-4h.

8. The method according to claim 5, characterized in that The organic solvent is one of methanol, acetonitrile and a mixed solvent of methanol + acetonitrile; the volume ratio of 1-hexene to the organic solvent is 1:10-1:30; the volume ratio of methanol to acetonitrile in the mixed solvent of methanol + acetonitrile is 1:1-3.

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