Titanium-silicon molecular sieve TS-1 nanosheets, their preparation methods and applications

Abstract

This invention relates to the field of molecular sieves, specifically to titanium-silicon molecular sieve TS-1 nanosheets, their preparation method, and applications. The invention uses tetrapropylammonium hydroxide, tetraethyl orthosilicate, tetrabutyl titanate, and urea as raw materials. The process involves crystallization followed by calcination to prepare titanium-silicon molecular sieve TS-1 nanosheets. This invention employs a urea-assisted synthesis method, where urea spontaneously disperses on the surface of the crystals perpendicular to the b-axis, inhibiting crystal growth along the b-axis direction. This results in the formation of sheet-like titanium-silicon molecular sieve TS-1 after calcination. This invention eliminates the need for isopropanol as a solvent and the regulation of hydrolysis of tetraethyl orthosilicate and tetrabutyl titanate, achieving low-cost synthesis of titanium-silicon molecular sieve TS-1 nanosheets and overcoming the technical defects of existing technologies where calcination leads to structural collapse.

Description

Technical Field

[0001] This invention relates to the field of molecular sieves, specifically to titanium-silicon molecular sieve TS-1 nanosheets, their preparation methods, and applications. Background Technology

[0002] Cyclohexanone oxime is commonly used as an intermediate in pesticides and insecticides, a stabilizer in rubber and plastics processing aids, and an important industrial raw material, primarily as an intermediate for nylon-6; nylon-6, also known as polyamide-6, is an engineering thermoplastic. It has wide applications in daily life, for example, in the production of fibers, clothing, textiles, tires, or tire cord fabrics.

[0003] Traditional cyclohexanone ammonium oxime processes are mainly divided into the Raschig process, the hydroxylamine phosphate process, and the NO reduction process. The Raschig process, also known as the hydroxylamine sulfate process, uses highly corrosive fuming sulfuric acid, and the products include ammonium sulfate, a fertilizer with very low practical value. The reactants and products of this method not only corrode process equipment, increasing costs, but also pollute the environment, contradicting the concept of green and ecological development. The hydroxylamine phosphate process is extremely complex, requiring numerous equipment, and the entire process requires the continuous use of H3PO4 to maintain the overall pH value at 1.8–2.0, resulting in harsh reaction conditions and the use of expensive Pd catalysts. The NO reduction process is complex, and the use and generation of H2SO4 corrode equipment.

[0004] In 1988, the Italian company EniChem SpA developed a liquid-phase ammonoximation method for cyclohexanone oxime. Specifically: The liquid-phase ammonoximation of cyclohexanone oxime involves the reaction of cyclohexanone with ammonia water using H2O2 as an oxidant, catalyzed by titanium silicate molecular sieve TS-1. The high activity of TS-1 is attributed to its ability to form strongly oxidizing Ti(IV)-peroxide groups on the titanium framework upon contact with hydrogen peroxide, thereby catalyzing the liquid-phase ammonoximation of cyclohexanone oxime. This method is simple, requiring only one step, with a reaction temperature of 60℃–80℃, mild conditions, and a water-based, environmentally friendly product. It exhibits high conversion, selectivity, yield, and atom utilization, meeting industrial requirements and thus has attracted considerable attention; it has already been industrially applied.

[0005] Current research primarily focuses on modifying the traditional titanium-silicon molecular sieve TS-1 to achieve higher cyclohexanone conversion and cyclohexanone oxime selectivity. The pores of the traditional titanium-silicon molecular sieve TS-1 are micropores, with active titanium species mainly located within these pores. However, the diameter of cyclohexanone molecules is similar to the diameter of the TS-1 pores, which severely hinders the diffusion of large-molecule reactants and products within the pores, resulting in low utilization of active sites and limiting further improvements in reactivity. Existing methods to address the diffusion problem of cyclohexanone within the traditional titanium-silicon molecular sieve TS-1 include: synthesizing mesoporous or hierarchical titanium-silicon molecular sieve TS-1; processing the synthesized titanium-silicon molecular sieve TS-1 to form hollow titanium-silicon molecular sieve TS-1; or synthesizing nanostructured titanium-silicon molecular sieve TS-1.

[0006] Mesoporous or hierarchical porous titanium-silicon molecular sieve TS-1 is mainly synthesized via a hard / soft template method. This method involves introducing hard / soft template agents into the TS-1 synthesis gel before crystallization. Hard template agents are typically relatively rigid solid materials, such as carbon nanomaterials and CaCO3. Introducing the hard template agent into the synthesis gel causes the TS-1 molecular sieve to crystallize and grow around it, ultimately yielding mesoporous TS-1. Its mesoporous characteristics are determined by the morphology and size of the hard template agent itself. However, the removal conditions for hard template agents are often quite harsh, thus often causing some damage to the structure of the titanium-silicon molecular sieve during the removal process. Furthermore, hard template agents are expensive, resulting in high synthesis costs and hindering industrial applications. Soft template agents are substances that can dissolve in titanium silica gel and have strong interactions with all its components, such as gelatin, cationic polymers, polydiene, or triblock copolymers. Adding soft template agents can construct rich and uniform mesopores inside the titanium silica molecular sieve TS-1 crystals. By using soft template agents of different molecular sizes, the mesopore size can be modulated. However, soft template agents compete with the micropore structure guiding agent tetrapropylammonium hydroxide during crystallization. Their addition can make the crystallization process of titanium silica molecular sieve TS-1 difficult to control, resulting in phase separation. In addition, the introduction of soft template agents can also affect the effective crystallization of Ti, which can enter the titanium silica molecular sieve framework and lead to the formation of anatase.

[0007] Introducing hollow structures into zeolites and forming hollow titanium-silicon molecular sieve TS-1 provides an alternative strategy to minimize diffusion barriers and potentially enhances the distribution of active sites during preparation. Desilication is the most common method for generating intracrystalline hollow structures in MFI-type zeolites, which involves placing pre-prepared conventional titanium-silicon molecular sieve TS-1 together with tetrapropylammonium hydroxide in a hydrothermal reactor for a secondary hydrothermal rearrangement. However, this method uses expensive tetrapropylammonium hydroxide, and the secondary hydrothermal process still requires filtration, washing, drying, and calcination, significantly increasing the synthesis cost.

[0008] Significant progress has been made in the selective control of the morphology of nanoparticles, nanoneedles, and nanosheets in the preparation of nanostructured zeolites. Nanostructured zeolites, due to their drastically reduced size in one or more dimensions, shorten diffusion paths for macromolecules and exhibit rapid mass transfer, thus attracting widespread attention. The small particle size of zeolite nanoparticles facilitates substrate diffusion in catalytic oxidation reactions; however, the excessively small size of nanocrystals makes separation from synthetic mixtures and reaction systems difficult. Particles that are too small cannot be separated by filtration and must be obtained through expensive centrifugation. Zeolite nanoneedles, with their elongated needle-like morphology and high rigidity, can even penetrate skin, causing injury to workers or accidents in experiments. Therefore, zeolite nanosheets are of great interest due to their excellent diffusivity, ease of separation, and greater health safety.

[0009] Two-dimensional layered titanium-silicon molecular sieve TS-1 refers to titanium-silicon molecular sieve TS-1 that grows regularly in two directions during its growth process, while growth is restricted in a third direction. Two-dimensional layered zeolites consist of several microporous crystalline sheets, each sheet having a unit thickness. Atoms within the zeolite layers are connected by strong covalent bonds, while adjacent zeolite layers interact through van der Waals forces, hydrogen bonds, or ionic bonds. This interaction between terminal silanol groups and charged structure-directing agents shortens the diffusion path and improves the accessibility of active sites, thus giving zeolite nanosheets excellent mass transfer properties. In recent years, researchers have developed many methods for synthesizing layered titanium-silicon molecular sieve TS-1 and applied it to the preparation of macromolecular reactants such as olefin epoxidation. However, most methods for synthesizing titanium-silicon molecular sieve TS-1 nanosheets use [C6H... 13 -N + (CH3)2-C6H 12 -N + (CH3)2-(CH2) 12 -O-(p-C6H4)2-O-(CH2) 12 -N + (CH3)2-C6H 12 -N + (CH3)2-C6H 13 ]

[0010] [OH - Long-chain surfactants, such as [4], are expensive and have complex synthesis processes, thus limiting the industrial application of sheet-like titanium-silicon molecular sieves. Furthermore, the preparation of TS-1 nanosheets requires calcination at 550°C for 6 hours to remove the structure-directing agents between the TS-1 nanosheets. However, the lack of support between the TS-1 nanosheets significantly reduces the space between them, potentially leading to structural collapse. Summary of the Invention

[0011] To address the shortcomings of existing technologies, the present invention aims to provide TS-1 nanosheets of titanium-silicon molecular sieves, their preparation method, and applications. This invention uses tetrapropylammonium hydroxide, tetraethyl orthosilicate, tetrabutyl titanate, and urea as raw materials. The process involves crystallization followed by calcination to prepare TS-1 nanosheets of titanium-silicon molecular sieves. This invention employs a urea-assisted synthesis method, where urea spontaneously disperses on the surface of the crystals perpendicular to the b-axis, inhibiting crystal growth along the b-axis direction. This results in the formation of sheet-like TS-1 titanium-silicon molecular sieves after calcination. This invention eliminates the need for isopropanol as a solvent and the regulation of hydrolysis of tetraethyl orthosilicate and tetrabutyl titanate, achieving low-cost synthesis of TS-1 nanosheets of titanium-silicon molecular sieves and overcoming the technical defects of existing technologies that lead to structural collapse during calcination.

[0012] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0013] This invention protects a method for preparing TS-1 titanium-silicon molecular sieve nanosheets, comprising the following steps:

[0014] Tetrapropylammonium hydroxide solution is mixed evenly with water, then tetraethyl orthosilicate is added and mixed evenly, and then urea is added to obtain a mixed solution. The mass percentage of tetrapropylammonium hydroxide solution is 25 wt%. Compared with the existing technology for preparing titanium-silicon molecular sieve TS-1, this invention applies urea to the preparation process of titanium-silicon molecular sieve TS-1 to obtain titanium-silicon molecular sieve TS-1 nanosheets.

[0015] Tetrabutyl titanate was added dropwise to the mixed solution and stirred until clear to obtain the pretreated solution.

[0016] The pretreated solution was crystallized to obtain crystals. During the crystallization process, urea was spontaneously dispersed on the surface of the crystal perpendicular to the b-axis, inhibiting the growth of the crystal along the b-axis.

[0017] The crystals were washed with water until neutral and then calcined to obtain titanium-silicon molecular sieve TS-1 nanosheets.

[0018] The molar ratio of tetraethyl orthosilicate to urea is 1:0.3 to 0.66. Urea is the main component in the formation of TS-1 nanosheets of titanium-silicon molecular sieves. Too little urea will not form a sheet-like morphology, while too much urea will not further alter the morphology, resulting in waste. Moreover, if the amount of urea exceeds this range, it will affect the catalytic effect of TS-1 nanosheets of titanium-silicon molecular sieves.

[0019] Preferably, the molar ratio of tetraethyl orthosilicate: tetrabutyl titanate: tetrapropylammonium hydroxide is 1:0.008-0.06:0.125-0.35.

[0020] Preferably, the crystallization method is to heat at 110℃~170℃ for 24h~80h.

[0021] Preferably, the calcination conditions are: calcination at 550℃ for 5 to 7 hours. If the calcination temperature is too low, it will not effectively remove the tetrapropylammonium hydroxide, organic matter, and urea inside the TS-1 nanosheets of the titanium-silicon molecular sieve. The organic matter is generated by the decomposition of tetraethyl orthosilicate and tetrabutyl titanate during crystallization. If the calcination temperature is too high, it will affect the structure of the TS-1 nanosheets of the titanium-silicon molecular sieve, causing structural collapse. Furthermore, calcination at 550℃ is mainly to remove the tetrapropylammonium hydroxide and the organic matter inside the pores of the TS-1 nanosheets of the titanium-silicon molecular sieve; urea is also removed.

[0022] Preferably, tetrabutyl titanate can be first dissolved in isopropanol to obtain a tetrabutyl titanate solution, and then the tetrabutyl titanate solution is added to the mixed solution. This invention allows tetrabutyl titanate to be directly added to the mixed solution without the need for isopropanol as a solvent for tetrabutyl titanate.

[0023] This invention also protects the TS-1 nanosheets of titanium-silicon molecular sieve prepared by the above preparation method.

[0024] This invention also protects the application of TS-1 titanium-silicon molecular sieve nanosheets in the preparation of catalysts for the ammoxidation of cyclohexanone to cyclohexanone oxime.

[0025] Preferably, cyclohexanone oxime is prepared according to the following steps:

[0026] Cyclohexanone oxime was obtained by mixing 30 wt% H2O2 as oxidant, water as solvent, tert-butanol as co-solvent, and titanium silicate molecular sieve TS-1 nanosheets as catalyst, with the solvent, co-solvent, 25 wt% NH3·H2O, oxidant and catalyst. The mixture was kept at 60-80℃ for 1-3 hours. After the reaction was completed, it was cooled to room temperature in an ice-water bath to obtain cyclohexanone oxime.

[0027] Preferably, the mass-to-molar ratio of TS-1 titanium silicate molecular sieve nanosheets to cyclohexanone is 25g to 32.5g: 1mol.

[0028] Preferably, the molar ratio of cyclohexanone:water:tert-butanol:NH3·H2O:H2O2 is 1:44~237:14~44:1.5~8:1~2.

[0029] Compared with the prior art, the beneficial effects of the present invention are:

[0030] 1. This invention uses tetrapropylammonium hydroxide, tetraethyl orthosilicate, tetrabutyl titanate, and urea as raw materials. The materials are first crystallized and then calcined to prepare titanium-silicon molecular sieve TS-1 nanosheets. Tetrabutyl titanate serves as the titanium source, tetraethyl orthosilicate as the silicon source, and tetrapropylammonium hydroxide as a structure directing agent, inducing TS-1 to form an MFI structure, facilitating the formation of titanium-silicon molecular sieve TS-1. Urea, as an inexpensive, readily available, green, and pollution-free material, is one of the simplest organic compounds and is widely used in industrial and agricultural production. This invention uses a urea-assisted synthesis method, where urea spontaneously disperses on the surface of the crystal perpendicular to the b-axis, inhibiting crystal growth along the b-axis. Furthermore, urea regulates the hydrolysis rate of tetraethyl orthosilicate and tetrabutyl titanate, thereby forming sheet-like titanium-silicon molecular sieve TS-1.

[0031] Furthermore, compared to existing technologies, in the sheet-like titanium-silicon molecular sieve TS-1 formed by long-chain surfactants, the structure is supported by the long-chain surfactants. After calcination, the long-chain surfactants decompose, leading to collapse due to the lack of support. However, not calcining will clog the pores. In this invention, the crystals are not supported by urea because urea inhibits their growth. Therefore, even calcination will not cause structural collapse.

[0032] 2. In this invention, urea is introduced into the preparation of titanium-silicon molecular sieve TS-1 nanosheets, which makes the crystallization process easy to control. The removal of template agent and urea will not affect the structure of titanium-silicon molecular sieve TS-1 nanosheets, and the titanium-silicon molecular sieve TS-1 nanosheets do not contain anatase.

[0033] 3. In this invention, urea is introduced into the preparation of titanium-silicon molecular sieve TS-1 nanosheets. The introduction of urea does not affect the effective crystallization of Ti and its entry into the molecular sieve framework. At the same time, it also regulates the hydrolysis rate of tetrabutyl titanate and tetraethyl orthosilicate, preventing the formation of anatase, which would inhibit the catalytic effect of cyclohexanone ammonium oxime. Because the hydrolysis rates of tetrabutyl titanate and tetraethyl orthosilicate are different, the faster hydrolysis rate of the titanate will lead to self-polymerization and the formation of anatase. However, Ti in anatase is not an active site and cannot react with H2O2 to produce Ti-OOH. Instead, it easily accelerates the ineffective decomposition of H2O2 and reduces the oxidation effect of H2O2.

[0034] 4. Under the condition of urea introduction, the synthesis of isopropanol-free titanium-silicon molecular sieve TS-1 nanosheets was also achieved, further reducing the synthesis cost.

[0035] 5. The titanium-silicon molecular sieve TS-1 nanosheets prepared by the urea-assisted synthesis method of this invention have good diffusion performance in the preparation of cyclohexanone oxime, that is, the reactants and products diffuse faster, and the active sites of titanium-silicon molecular sieve TS-1 nanosheets can be easily used for adsorption and desorption. The preparation process is simple and inexpensive, and it has high catalytic activity for the liquid-phase cyclohexanone amination oxime reaction. Attached Figure Description

[0036] Figure 1 The image shows the XRD pattern of the titanium-silicon molecular sieve TS-1 nanosheets from Example 1.

[0037] Figure 2 This is a SEM image of the titanium-silicon molecular sieve TS-1 nanosheets from Example 1.

[0038] Figure 3 The image shows the XRD pattern of the titanium-silicon molecular sieve TS-1 nanosheets from Example 2.

[0039] Figure 4 This is a SEM image of the titanium-silicon molecular sieve TS-1 nanosheets from Example 2.

[0040] Figure 5 The image shows the XRD pattern of the titanium-silicon molecular sieve TS-1 nanosheets from Example 3.

[0041] Figure 6 This is a SEM image of the titanium-silicon molecular sieve TS-1 nanosheets from Example 3.

[0042] Figure 7 The image shows the XRD pattern of the ordinary titanium-silicon molecular sieve TS-1, which is Comparative Example 1.

[0043] Figure 8 The image shows the SEM image of the ordinary titanium-silicon molecular sieve TS-1, which is Comparative Example 1. Detailed Implementation

[0044] The specific embodiments of the present invention are described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention. Unless otherwise specified, the experimental methods described in the embodiments of the present invention are conventional methods.

[0045] This invention provides a method for preparing TS-1 nanosheets of titanium-silicon molecular sieve using urea. Compared with the existing hard-template method for preparing mesoporous titanium-silicon molecular sieve TS-1, the hard template agent is insoluble in the solvent, and the nucleation and growth mechanism does not conform to the traditional homogeneous nucleation and growth mechanism, but is generally heterogeneous nucleation, making the nucleation and growth mechanism more complex. Furthermore, the hard template is difficult to remove, and the removal process can affect the crystal structure of the titanium-silicon molecular sieve TS-1. Compared with the soft-template method for preparing mesoporous titanium-silicon molecular sieve TS-1, urea is cheaper, more readily available, environmentally friendly, and easier to remove than soft template agents, thus not affecting the structure of the titanium-silicon molecular sieve TS-1 during the removal process. In addition, the urea of ​​this invention does not compete with the micropore structure-directing agent tetrapropylammonium hydroxide during crystallization, making the crystallization process easier to control and preventing phase separation.

[0046] Compared with the existing technology for preparing hollow titanium-silicon molecular sieve TS-1, urea is added during the synthesis of titanium-silicon molecular sieve TS-1 nanosheets, eliminating the need for secondary hydrothermal treatment. At the same time, urea is much cheaper than tetrapropylammonium hydroxide, effectively reducing production costs.

[0047] The technical solution of the present invention will be further explained and illustrated below with examples and comparative examples, as detailed below:

[0048] Example 1

[0049] The preparation method of TS-1 titanium silicate molecular sieve nanosheets includes the following steps:

[0050] S1. Weigh the raw materials according to the molar ratio of tetraethyl orthosilicate: tetrabutyl titanate: tetrapropylammonium hydroxide: H2O: urea of ​​1:0.01:0.25:23:0.5.

[0051] S2. Mix 20.336g of 25wt% tetrapropylammonium hydroxide solution and 26.148g of deionized water and stir for 30min. Then add 20.833g of tetraethyl orthosilicate and stir for 2h. After the solution becomes clear, add 3g of urea to obtain a mixed solution.

[0052] 0.34 g of tetrabutyl titanate was added dropwise to 15.3 g of isopropanol while stirring to obtain a tetrabutyl titanate solution.

[0053] S3. Add the tetrabutyl titanate solution to the mixed solution, stir until clear, and then heat at 80°C to evaporate the alcohol. The alcohol here includes isopropanol and alcohols in tetraethyl orthosilicate and tetrabutyl titanate, etc. Add water dropwise to keep the water volume constant to obtain the pretreated solution.

[0054] S4. The pretreated solution was placed in a hydrothermal reactor with a polytetrafluoroethylene liner and crystallized at 170°C for 72 hours. Then, it was washed with deionized water until the filtrate was neutral. It was dried at 60°C for 12 hours and then calcined at 550°C for 6 hours to obtain titanium silicon molecular sieve TS-1 nanosheets.

[0055] The XRD characterization results of the titanium-silicon molecular sieve TS-1 nanosheets obtained in Example 1 are as follows: Figure 1 As shown, the SEM characterization results are as follows: Figure 2 As shown in the figure, the structure and crystallinity of the prepared titanium-silicon molecular sieve TS-1 nanosheet crystals (MFI) remained unchanged, and the morphology was sheet-like.

[0056] The cyclohexanone ammoniation reaction was carried out using the titanium-silicon molecular sieve TS-1 nanosheets from Example 1, including the following steps:

[0057] S1. 0.075g of catalyst titanium silicate molecular sieve TS-1 nanosheets, 0.196g of cyclohexanone, 7.5g of water, 5.9g of tert-butanol, 0.561g of NH3·H2O and 0.227g of H2O2 were added to a flask. The NH3·H2O was 25wt% and the H2O2 was 30wt%. The flask was heated to 80℃ and kept at that temperature for 3h. After the reaction was completed, it was cooled to room temperature in an ice-water bath to obtain cyclohexanone oxime.

[0058] S2. Add 6g of ethanol and 0.15g of diethylene glycol monoethyl ether to the reacted solution. Ethanol and diethylene glycol monoethyl ether are used for quantitative determination of cyclohexanone and cyclohexanone oxime in gas chromatography. Diethylene glycol monoethyl ether is used as an internal standard, and ethanol is used as a solvent to dissolve the diethylene glycol monoethyl ether. After stirring and mixing thoroughly, the catalyst is removed by centrifugation. Using diethylene glycol monoethyl ether as an internal standard, the internal standard method is employed, and detection is performed by gas chromatography. The conversion rate of cyclohexanone and the selectivity for cyclohexanone oxime are calculated according to the following formula:

[0059]

[0060] In the formula, C0 is the concentration of cyclohexanone before the reaction, C1 is the concentration of cyclohexanone after the reaction, and C2 is the concentration of cyclohexanone oxime formed.

[0061] Catalyst activity evaluation results: The conversion rate of cyclohexanone was 94.8%, and the selectivity for cyclohexanone oxime was 100%.

[0062] Example 2

[0063] The preparation method of the titanium-silicon molecular sieve TS-1 nanosheets is the same as that in Example 1, except that the molar ratio of tetrapropylammonium hydroxide to tetraethyl orthosilicate is changed from 0.25:1 to 0.3:1, and includes the following steps:

[0064] S1. Weigh the raw materials according to the molar ratio of tetraethyl orthosilicate: tetrabutyl titanate: tetrapropylammonium hydroxide: H2O: urea of ​​1:0.01:0.3:23:0.5.

[0065] S2. Mix 24.403g of 25wt% tetrapropylammonium hydroxide solution and 26.148g of deionized water and stir for 30min. Then add 20.833g of tetraethyl orthosilicate and stir for 2h. After the solution becomes clear, add 3g of urea to obtain a mixed solution.

[0066] 0.34 g of tetrabutyl titanate was added dropwise to 15.3 g of isopropanol while stirring to obtain a tetrabutyl titanate solution.

[0067] S3. Add the tetrabutyl titanate solution to the mixed solution, stir until clear, then heat at 80°C to evaporate the alcohol, and add water dropwise to keep the water volume constant to obtain the pretreated solution.

[0068] S4. The pretreated solution was placed in a hydrothermal reactor with a polytetrafluoroethylene liner and crystallized at 170°C for 72 hours. Then, it was washed with deionized water until the filtrate was neutral. It was dried at 60°C for 12 hours and then calcined at 550°C for 6 hours to obtain titanium silicon molecular sieve TS-1 nanosheets.

[0069] The XRD characterization results of the titanium-silicon molecular sieve TS-1 nanosheets obtained in Example 2 are as follows: Figure 3 As shown, the SEM characterization results are as follows: Figure 4 As shown in the figure, the structure and crystallinity of the prepared titanium-silicon molecular sieve TS-1 nanosheet crystals (MFI) remained unchanged, and the morphology was sheet-like.

[0070] The cyclohexanone ammoniation reaction was carried out using the titanium-silicon molecular sieve TS-1 nanosheets from Example 2, including the following steps:

[0071] S1. 0.075g of catalyst titanium silicate molecular sieve TS-1 nanosheets, 0.196g of cyclohexanone, 7.5g of water, 5.9g of tert-butanol, 0.561g of NH3·H2O and 0.227g of H2O2 were added to a flask. The NH3·H2O was 25wt% and the H2O2 was 30wt%. The flask was heated to 80℃ and kept at that temperature for 3h. After the reaction was completed, it was cooled to room temperature in an ice-water bath to obtain cyclohexanone oxime.

[0072] S2. Add 6g of ethanol and 0.15g of diethylene glycol monoethyl ether to the reacted solution, stir and mix thoroughly, then remove the catalyst by centrifugation. Use diethylene glycol monoethyl ether as an internal standard, and detect it by gas chromatography using the internal standard method.

[0073] Catalyst activity evaluation results: The conversion rate of cyclohexanone was 97.3%, and the selectivity for cyclohexanone oxime was 100%.

[0074] Example 3

[0075] The preparation method of TS-1 titanium-silicon molecular sieve nanosheets is the same as that in Example 1, except that tetrabutyl titanate is directly added dropwise to the mixed solution without the addition of isopropanol, including the following steps:

[0076] S1. Weigh the raw materials according to the molar ratio of tetraethyl orthosilicate: tetrabutyl titanate: tetrapropylammonium hydroxide: H2O: urea of ​​1:0.01:0.25:23:0.5.

[0077] S2. Mix 20.336g of 25wt% tetrapropylammonium hydroxide solution and 26.148g of deionized water and stir for 30min. Then add 20.833g of tetraethyl orthosilicate and stir for 2h. After the solution becomes clear, add 3g of urea to obtain a mixed solution.

[0078] S3. Add 0.34g of tetrabutyl titanate dropwise to the mixed solution while stirring until the solution becomes clear, thus obtaining the pretreated solution.

[0079] S4. The pretreated solution was placed in a hydrothermal reactor with a polytetrafluoroethylene liner and crystallized at 170°C for 72 hours. Then, it was washed with deionized water until the filtrate was neutral. It was dried at 60°C for 12 hours and then calcined at 550°C for 6 hours to obtain titanium silicon molecular sieve TS-1 nanosheets.

[0080] The XRD characterization results of the titanium-silicon molecular sieve TS-1 nanosheets obtained in Example 3 are as follows: Figure 5 As shown, the SEM characterization results are as follows: Figure 6 As shown in the figure, the structure and crystallinity of the prepared titanium-silicon molecular sieve TS-1 nanosheet crystals (MFI) remained unchanged, and the morphology was sheet-like.

[0081] The cyclohexanone ammoniation reaction was carried out using the titanium-silicon molecular sieve TS-1 nanosheets from Example 3, including the following steps:

[0082] S1. 0.075g of catalyst titanium silicate molecular sieve TS-1 nanosheets, 0.196g of cyclohexanone, 7.5g of water, 5.9g of tert-butanol, 0.561g of NH3·H2O and 0.227g of H2O2 were added to a flask. The NH3·H2O was 25wt% and the H2O2 was 30wt%. The flask was heated to 80℃ and kept at that temperature for 3h. After the reaction was completed, it was cooled to room temperature in an ice-water bath to obtain cyclohexanone oxime.

[0083] S2. Add 6g of ethanol and 0.15g of diethylene glycol monoethyl ether to the reacted solution, stir and mix thoroughly, then remove the catalyst by centrifugation. Use diethylene glycol monoethyl ether as an internal standard, and detect it by gas chromatography using the internal standard method.

[0084] Catalyst activity evaluation results: The conversion rate of cyclohexanone was 95.28%, and the selectivity for cyclohexanone oxime was 100%.

[0085] Example 4

[0086] The preparation method of the titanium-silicon molecular sieve TS-1 nanosheets is the same as that in Example 1, except that the molar ratio of tetrabutyl titanate to tetraethyl orthosilicate is changed from 0.01:1 to 0.06:1, and includes the following steps:

[0087] S1. Weigh the raw materials according to the molar ratio of tetraethyl orthosilicate: tetrabutyl titanate: tetrapropylammonium hydroxide: H2O: urea of ​​1:0.06:0.25:23:0.5.

[0088] S2. Mix 20.336g of 25wt% tetrapropylammonium hydroxide solution and 26.148g of deionized water and stir for 30min. Then add 20.833g of tetraethyl orthosilicate and stir for 2h. After the solution becomes clear, add 3g of urea to obtain a mixed solution.

[0089] 0.34 g of tetrabutyl titanate was added dropwise to 15.3 g of isopropanol while stirring to obtain a tetrabutyl titanate solution.

[0090] S3. Add the tetrabutyl titanate solution to the mixed solution, stir until clear, then heat at 80°C to evaporate the alcohol, and add water dropwise to keep the water volume constant to obtain the pretreated solution.

[0091] S4. The pretreated solution was placed in a hydrothermal reactor with a polytetrafluoroethylene liner and crystallized at 170°C for 72 hours. Then, it was washed with deionized water until the filtrate was neutral. It was dried at 60°C for 12 hours and then calcined at 550°C for 6 hours to obtain titanium silicon molecular sieve TS-1 nanosheets.

[0092] The cyclohexanone ammoniation reaction was carried out using the titanium-silicon molecular sieve TS-1 nanosheets from Example 4, including the following steps:

[0093] S1. 0.075g of catalyst titanium silicate molecular sieve TS-1 nanosheets, 0.196g of cyclohexanone, 7.5g of water, 5.9g of tert-butanol, 0.561g of NH3·H2O and 0.227g of H2O2 were added to a flask. The NH3·H2O was 25wt% and the H2O2 was 30wt%. The flask was heated to 80℃ and kept at that temperature for 3h. After the reaction was completed, it was cooled to room temperature in an ice-water bath to obtain cyclohexanone oxime.

[0094] S2. Add 6g of ethanol and 0.15g of diethylene glycol monoethyl ether to the reacted solution, stir and mix thoroughly, then remove the catalyst by centrifugation. Use diethylene glycol monoethyl ether as an internal standard, and detect it by gas chromatography using the internal standard method.

[0095] Catalyst activity evaluation results: The conversion rate of cyclohexanone was 57.34%, and the selectivity for cyclohexanone oxime was 98.87%.

[0096] Example 5

[0097] The preparation method of TS-1 titanium-silicon molecular sieve nanosheets is the same as that in Example 1, except that the molar ratio of urea to tetraethyl orthosilicate is changed from 0.5:1 to 0.66:1, the molar ratio of tetrapropylammonium hydroxide to tetraethyl orthosilicate is changed from 0.25:1 to 0.35:1, the molar ratio of water to tetraethyl orthosilicate is changed from 23:1 to 40:1, the amount of isopropanol is changed from 15.3g to 17g, the crystallization time is increased from 72h to 80h, and the calcination time is increased from 6h to 7h. The method includes the following steps:

[0098] S1. Weigh the raw materials according to the molar ratio of tetraethyl orthosilicate: tetrabutyl titanate: tetrapropylammonium hydroxide: H2O: urea of ​​1:0.01:0.35:40:0.66.

[0099] S2. Mix 28.472g of 25wt% tetrapropylammonium hydroxide solution and 56.75g of deionized water and stir for 30min. Then add 20.833g of tetraethyl orthosilicate and stir for 2h. After the solution becomes clear, add 4g of urea to obtain a mixed solution.

[0100] 0.34 g of tetrabutyl titanate was added dropwise to 17 g of isopropanol while stirring to obtain a tetrabutyl titanate solution.

[0101] S3. Add the tetrabutyl titanate solution to the mixed solution, stir until clear, then heat at 80°C to evaporate the alcohol, and add water dropwise to keep the water volume constant to obtain the pretreated solution.

[0102] S4. The pretreated solution was placed in a hydrothermal reactor with a polytetrafluoroethylene liner and crystallized at 170°C for 80 hours. Then, it was washed with deionized water until the filtrate was neutral. It was dried at 60°C for 12 hours and then calcined at 550°C for 7 hours to obtain titanium silicon molecular sieve TS-1 nanosheets.

[0103] The cyclohexanone ammoniation reaction was carried out using the titanium-silicon molecular sieve TS-1 nanosheets from Example 5, including the following steps:

[0104] S1. 0.075g of catalyst titanium silicate molecular sieve TS-1 nanosheets, 0.196g of cyclohexanone, 7.5g of water, 5.9g of tert-butanol, 0.561g of NH3·H2O and 0.227g of H2O2 were added to a flask. The NH3·H2O was 25wt% and the H2O2 was 30wt%. The flask was heated to 80℃ and kept at that temperature for 3h. After the reaction was completed, it was cooled to room temperature in an ice-water bath to obtain cyclohexanone oxime.

[0105] S2. Add 6g of ethanol and 0.15g of diethylene glycol monoethyl ether to the reacted solution, stir and mix thoroughly, then remove the catalyst by centrifugation. Use diethylene glycol monoethyl ether as an internal standard, and detect it by gas chromatography using the internal standard method.

[0106] Catalyst activity evaluation results: The conversion rate of cyclohexanone was 94.77%, and the selectivity for cyclohexanone oxime was 100%.

[0107] Example 6

[0108] The preparation method of TS-1 nanosheets of titanium-silicon molecular sieve is the same as that in Example 1, except that the molar ratio of tetrabutyl titanate to tetraethyl orthosilicate is replaced by 0.008:1 instead of 0.01:1, and tetrabutyl titanate is directly added dropwise to the mixed solution without the addition of isopropanol; the molar ratio of urea to tetraethyl orthosilicate is replaced by 0.3:1 instead of 0.5:1; the molar ratio of tetrapropylammonium hydroxide to tetraethyl orthosilicate is replaced by 0.125:1 instead of 0.25:1; the molar ratio of water to tetraethyl orthosilicate is replaced by 8:1 instead of 23:1; the crystallization temperature is replaced by 110℃ instead of 170℃; the crystallization time is reduced from 72h to 24h; and the calcination time is reduced from 6h to 5h. The method includes the following steps:

[0109] S1. Weigh the raw materials according to the molar ratio of tetraethyl orthosilicate: tetrabutyl titanate: tetrapropylammonium hydroxide: H2O: urea of ​​1:0.008:0.125:8:0.3.

[0110] S2. Mix 10.168g of 25wt% tetrapropylammonium hydroxide solution and 9.095g of deionized water and stir for 30min. Then add 20.833g of tetraethyl orthosilicate and stir for 2h. After the solution becomes clear, add 1.8g of urea to obtain a mixed solution.

[0111] S3. While stirring, add 0.34g of tetrabutyl titanate dropwise to the mixed solution until the solution is clear. Then heat at 80℃ to evaporate the alcohol and add water dropwise to keep the water volume constant to obtain the pretreated solution.

[0112] S4. The pretreated solution was placed in a hydrothermal reactor with a polytetrafluoroethylene liner and crystallized at 110°C for 24 hours. Then it was washed with deionized water until the filtrate was neutral. It was dried at 60°C for 12 hours and then calcined at 550°C for 5 hours to obtain titanium silicon molecular sieve TS-1 nanosheets.

[0113] The cyclohexanone ammoniation reaction was carried out using the titanium-silicon molecular sieve TS-1 nanosheets from Example 6, including the following steps:

[0114] S1. 0.075g of catalyst titanium silicate molecular sieve TS-1 nanosheets, 0.196g of cyclohexanone, 7.5g of water, 5.9g of tert-butanol, 0.561g of NH3·H2O and 0.227g of H2O2 were added to a flask. The NH3·H2O was 25wt% and the H2O2 was 30wt%. The flask was heated to 80℃ and kept at that temperature for 3h. After the reaction was completed, it was cooled to room temperature in an ice-water bath to obtain cyclohexanone oxime.

[0115] S2. Add 6g of ethanol and 0.15g of diethylene glycol monoethyl ether to the reacted solution, stir and mix thoroughly, then remove the catalyst by centrifugation. Use diethylene glycol monoethyl ether as an internal standard, and detect it by gas chromatography using the internal standard method.

[0116] Catalyst activity evaluation results: The conversion rate of cyclohexanone was 68.42%, and the selectivity for cyclohexanone oxime was 100%.

[0117] Example 7

[0118] The cyclohexanone amination reaction is the same as the preparation steps in Example 1, except that the amount of the catalyst, titanium silicate molecular sieve TS-1 nanosheets, is replaced from 0.075g to 0.125g, and the reaction time is reduced from 3h to 1h. The reaction includes the following steps:

[0119] S1. 0.125g of catalyst titanium silicate molecular sieve TS-1 nanosheets, 0.196g of cyclohexanone, 7.5g of water, 5.9g of tert-butanol, 0.561g of NH3·H2O and 0.227g of H2O2 were added to a flask. The NH3·H2O was 25wt% and the H2O2 was 30wt%. The flask was heated to 80℃ and kept at that temperature for 1h. After the reaction was completed, it was cooled to room temperature in an ice-water bath to obtain cyclohexanone oxime.

[0120] S2. Add 6g of ethanol and 0.15g of diethylene glycol monoethyl ether to the mixed solution after the reaction, stir and mix thoroughly, then remove the catalyst by centrifugation. Use diethylene glycol monoethyl ether as an internal standard, and detect it by gas chromatography using the internal standard method.

[0121] Catalyst activity evaluation results: The conversion rate of cyclohexanone was 74.38%, and the selectivity for cyclohexanone oxime was 99.8%.

[0122] Example 8

[0123] The cyclohexanone amination reaction was carried out using the same steps as in Example 1, except that the amount of the catalyst, titanium silicate molecular sieve TS-1 nanosheets, was replaced from 0.075 g to 0.05 g, the amount of tert-butanol from 5.9 g to 6.01 g, the amount of water from 7.5 g to 8.5 g, the amount of NH3·H2O from 0.561 g to 1.12 g, the amount of H2O2 from 0.227 g to 0.453 g, and the reaction time was increased from 3 h to 5 h. The reaction included the following steps:

[0124] S1. 0.05g of catalyst titanium silicate molecular sieve TS-1 nanosheets, 0.196g of cyclohexanone, 8.5g of water, 6.01g of tert-butanol, 1.12g of NH3·H2O and 0.453g of H2O2 were added to a flask. The NH3·H2O was 25wt% and the H2O2 was 30wt%. The flask was heated to 80℃ and kept at that temperature for 5h. After the reaction was completed, it was cooled to room temperature in an ice-water bath to obtain cyclohexanone oxime.

[0125] S2. Add 6g of ethanol and 0.15g of diethylene glycol monoethyl ether to the reacted solution, stir and mix thoroughly, then remove the catalyst by centrifugation. Use diethylene glycol monoethyl ether as an internal standard, and detect it by gas chromatography using the internal standard method.

[0126] Catalyst activity evaluation results: The conversion rate of cyclohexanone was 100%, and the selectivity for cyclohexanone oxime was 100%.

[0127] Example 9

[0128] The cyclohexanone amination reaction is the same as the preparation steps in Example 1, except that the amount of NH3·H2O is replaced from 0.561g to 0.2125g, and the amount of H2O2 is replaced from 0.227g to 0.26g. The reaction includes the following steps:

[0129] S1. 0.075g of catalyst titanium silicate molecular sieve TS-1 nanosheets, 0.196g of cyclohexanone, 7.5g of water, 5.9g of tert-butanol, 0.2125g of NH3·H2O and 0.26g of H2O2 were added to a flask. The NH3·H2O was 25wt% and the H2O2 was 30wt%. The flask was heated to 80℃ and kept at that temperature for 3h. After the reaction was completed, it was cooled to room temperature in an ice-water bath to obtain cyclohexanone oxime.

[0130] S2. Add 6g of ethanol and 0.15g of diethylene glycol monoethyl ether to the reacted solution, stir and mix thoroughly, then remove the catalyst by centrifugation. Use diethylene glycol monoethyl ether as an internal standard, and detect it by gas chromatography using the internal standard method.

[0131] Catalyst activity evaluation results: The conversion rate of cyclohexanone was 96.22%, and the selectivity for cyclohexanone oxime was 100%.

[0132] Example 10

[0133] The cyclohexanone amination reaction is the same as the preparation steps in Example 1, except that the amount of tert-butanol is replaced by 2g instead of 5.9g, the amount of water is replaced by 1.584g instead of 7.5g, the amount of NH3·H2O is replaced by 0.182g instead of 0.561g, the amount of H2O2 is replaced by 0.26g instead of 0.227g, and the reaction temperature is replaced by 60℃ instead of 80℃. The reaction includes the following steps:

[0134] S1. 0.075g of catalyst titanium silicate molecular sieve TS-1 nanosheets, 0.196g of cyclohexanone, 1.584g of water, 2g of tert-butanol, 0.182g of NH3·H2O and 0.26g of H2O2 were added to a flask. The NH3·H2O was 25wt% and the H2O2 was 30wt%. The flask was heated to 60℃ and kept at that temperature for 3h. After the reaction was completed, it was cooled to room temperature in an ice-water bath to obtain cyclohexanone oxime.

[0135] S2. Add 6g of ethanol and 0.15g of diethylene glycol monoethyl ether to the reacted solution, stir and mix thoroughly, then remove the catalyst by centrifugation. Use diethylene glycol monoethyl ether as an internal standard, and detect it by gas chromatography using the internal standard method.

[0136] Catalyst activity evaluation results: The conversion rate of cyclohexanone was 59.22%, and the selectivity for cyclohexanone oxime was 87.43%.

[0137] Comparative Example 1

[0138] The preparation method of ordinary titanium-silicon molecular sieve TS-1 includes the following steps:

[0139] S1. Weigh the raw materials according to the molar ratio of tetraethyl orthosilicate: tetrabutyl titanate: tetrapropylammonium hydroxide: H2O of 1:0.01:0.3:23.

[0140] S2. Mix 24.403g of 25wt% tetrapropylammonium hydroxide solution and 26.148g of deionized water and stir for 30min. Then add 20.833g of tetraethyl orthosilicate and stir for 2h to obtain a mixed solution.

[0141] 0.34 g of tetrabutyl titanate was added dropwise to 15.3 g of isopropanol while stirring to obtain a tetrabutyl titanate solution.

[0142] S3. Add the tetrabutyl titanate solution to the mixed solution, stir until clear, then heat at 80°C to evaporate the alcohol, and add water dropwise to keep the water volume constant to obtain the pretreated solution.

[0143] S4. The pretreated solution was placed in a hydrothermal reactor with a polytetrafluoroethylene liner and crystallized at 170°C for 72 hours. Then it was washed with deionized water until the filtrate was neutral. It was dried at 60°C for 12 hours and then calcined at 550°C for 6 hours to obtain ordinary titanium-silicon molecular sieve TS-1.

[0144] The XRD characterization results of ordinary titanium silicate molecular sieve TS-1 are as follows: Figure 7 As shown, the SEM characterization results are as follows: Figure 8 As shown in the figure, the prepared ordinary titanium-silicon molecular sieve TS-1 crystal MFI has good structure and crystallinity, and its morphology is spherical.

[0145] The cyclohexanone aminooximation reaction was carried out using ordinary titanium-silicon molecular sieve TS-1 (Comparative Example 1), including the following steps:

[0146] S1. Add 0.075g of ordinary titanium silicate molecular sieve TS-1, 0.196g of cyclohexanone, 7.5g of water, 5.9g of tert-butanol, 0.561g of NH3·H2O and 0.227g of H2O2 to a flask. The NH3·H2O is 25wt% and the H2O2 is 30wt%. Heat the flask to 80℃ and keep it at that temperature for 3h. After the reaction is complete, cool it to room temperature in an ice-water bath to obtain cyclohexanone oxime.

[0147] S2. Add 6g of ethanol and 0.15g of diethylene glycol monoethyl ether to the reacted solution, stir and mix thoroughly, then remove the catalyst by centrifugation. Use diethylene glycol monoethyl ether as an internal standard, and detect it by gas chromatography using the internal standard method.

[0148] Catalyst activity evaluation results: The conversion rate of cyclohexanone was 87.1%, and the selectivity for cyclohexanone oxime was 100%.

[0149] Comparative Example 2

[0150] The preparation method of pure silica molecular sieve TS-1 nanosheets includes the following steps:

[0151] S1. Weigh the raw materials according to the molar ratio of tetraethyl orthosilicate: tetrabutyl titanate: tetrapropylammonium hydroxide: H2O: urea of ​​1:0:0.125:8:0.5.

[0152] S2. Mix 10.168g of 25wt% tetrapropylammonium hydroxide solution and 9.095g of deionized water and stir for 30min. Then add 20.833g of tetraethyl orthosilicate and stir for 2h. After the solution becomes clear, add 3g of urea to obtain a mixed solution.

[0153] S3. Add 15.3g of isopropanol to the mixed solution, stir until clear, then heat at 80℃ to evaporate the alcohol, and add water dropwise to keep the water volume constant to obtain the pretreated solution.

[0154] S4. The pretreated solution was placed in a hydrothermal reactor with a polytetrafluoroethylene liner and crystallized at 170°C for 72 hours. Then, it was washed with deionized water until the filtrate was neutral. It was dried at 60°C for 12 hours and then calcined at 550°C for 6 hours to obtain pure silicon molecular sieve TS-1 nanosheets.

[0155] The cyclohexanone aminooximation reaction was carried out using pure silica molecular sieve TS-1 nanosheets (Comparative Example 2), including the following steps:

[0156] 0.075 g of catalyst-pure silica molecular sieve TS-1 nanosheets, 0.196 g of cyclohexanone, 7.5 g of water, 5.9 g of tert-butanol, 0.561 g of NH3·H2O, and 0.227 g of H2O2 were added to a flask. The NH3·H2O was 25 wt% and the H2O2 was 30 wt%. The mixture was heated to 80 °C and kept at that temperature for 3 h. After the reaction was completed, the mixture was cooled to room temperature in an ice-water bath to obtain cyclohexanone oxime.

[0157] S2. Add 6g of ethanol and 0.15g of diethylene glycol monoethyl ether to the reacted solution, stir and mix thoroughly, then remove the catalyst by centrifugation. Use diethylene glycol monoethyl ether as an internal standard, and detect it by gas chromatography using the internal standard method.

[0158] Catalyst activity evaluation results: The conversion rate of cyclohexanone was 0%, and the selectivity for cyclohexanone oxime was 0%.

[0159] Comparative Example 3

[0160] The cyclohexanone amination reaction follows the same steps as in Example 1, except that it does not use the titanium silicate molecular sieve TS-1 nanosheets as a catalyst, and the reaction is carried out for 0 hours. The reaction includes the following steps:

[0161] 0.196 g of cyclohexanone, 7.5 g of water, 5.9 g of tert-butanol, 0.561 g of NH3·H2O and 0.227 g of H2O2 were added to a flask. The NH3·H2O was 25 wt% and the H2O2 was 30 wt%. The flask was heated to 80 °C and kept at that temperature for 0 h. That is, when the temperature reached 80 °C, it was cooled in an ice bath. After the reaction was completed, it was cooled to room temperature in an ice-water bath to obtain cyclohexanone oxime.

[0162] S2. Add 6g of ethanol and 0.15g of diethylene glycol monoethyl ether to the reacted solution, stir and mix thoroughly, then remove the catalyst by centrifugation. Use diethylene glycol monoethyl ether as an internal standard, and detect it by gas chromatography using the internal standard method.

[0163] Activity evaluation results: The conversion rate of cyclohexanone was 0%, and the selectivity for cyclohexanone oxime was 0%.

[0164] Comparative Example 4

[0165] The cyclohexanone amination reaction is the same as the preparation steps in Example 1, except that it does not contain NH3·H2O and H2O2, and includes the following steps:

[0166] 0.075g of catalyst titanium silicate molecular sieve TS-1 nanosheets, 0.196g of cyclohexanone, 7.5g of water and 5.9g of tert-butanol were added to a flask. The flask was heated to 60℃ and kept at that temperature for 5h. After the reaction was completed, it was cooled to room temperature in an ice-water bath to obtain cyclohexanone oxime.

[0167] S2. Add 6g of ethanol and 0.15g of diethylene glycol monoethyl ether to the reacted solution, stir and mix thoroughly, then remove the catalyst by centrifugation. Use diethylene glycol monoethyl ether as an internal standard, and detect it by gas chromatography using the internal standard method.

[0168] Activity evaluation results: The conversion rate of cyclohexanone was 0%, and the selectivity for cyclohexanone oxime was 0%.

[0169] Comparative Example 5

[0170] The cyclohexanone amination reaction is the same as the preparation steps in Example 1, except that it does not contain the solvent H2O, and includes the following steps:

[0171] 0.075g of catalyst titanium silicate molecular sieve TS-1 nanosheets, 0.196g of cyclohexanone, 5.9g of tert-butanol, 0.561g of NH3·H2O and 0.227g of H2O2 were added to a flask. The flask was heated to 80℃ and kept at that temperature for 3h. After the reaction was completed, it was cooled to room temperature in an ice-water bath to obtain cyclohexanone oxime.

[0172] S2. Add 6g of ethanol and 0.15g of diethylene glycol monoethyl ether to the reacted solution, stir and mix thoroughly, then remove the catalyst by centrifugation. Use diethylene glycol monoethyl ether as an internal standard, and detect it by gas chromatography using the internal standard method.

[0173] The activity evaluation results of the TS-1 nanosheet titanium silicate molecular sieve catalyst showed that the conversion rate of cyclohexanone was 57.54% and the selectivity for cyclohexanone oxime was 95.85%.

[0174] Comparative Example 6

[0175] The cyclohexanone amination reaction is the same as the preparation steps in Example 1, except that it does not contain the co-solvent tert-butanol, and includes the following steps:

[0176] 0.075g of catalyst titanium silicate molecular sieve TS-1 nanosheets, 0.196g of cyclohexanone, 7.5g of water, 0.561g of NH3·H2O and 0.227g of H2O2 were added to a flask. The flask was heated to 80℃ and kept at that temperature for 3h. After the reaction was completed, it was cooled to room temperature in an ice-water bath to obtain cyclohexanone oxime.

[0177] S2. Add 6g of ethanol and 0.15g of diethylene glycol monoethyl ether to the reacted solution, stir and mix thoroughly, then remove the catalyst by centrifugation. Use diethylene glycol monoethyl ether as an internal standard, and detect it by gas chromatography using the internal standard method.

[0178] Catalyst activity evaluation results: The conversion rate of cyclohexanone was 100%, and the selectivity for cyclohexanone oxime was 39.68%.

[0179] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications should fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing TS-1 nanosheets of titanium-silicon molecular sieve, characterized in that, Without adding isopropanol, tetrabutyl titanate is added dropwise directly to the mixed solution, including the following steps: S1. The molar ratio of tetraethyl orthosilicate: tetrabutyl titanate: tetrapropylammonium hydroxide: H2O: urea is 1:0.01:0.

25. Weigh the raw materials at a ratio of 23:0.5; S2. Mix 20.336g of 25wt% tetrapropylammonium hydroxide solution and 26.148g of deionized water and stir for 30min. Then add 20.833g of tetraethyl orthosilicate and stir for 2h. After the solution becomes clear, add 3g of urea to obtain a mixed solution. S3. While stirring, add 0.34g of tetrabutyl titanate dropwise to the mixed solution until the solution is clear. Then heat at 80℃ to evaporate the alcohol and add water dropwise to keep the water volume constant to obtain the pretreated solution. S4. The pretreatment solution was placed in a hydrothermal reactor with a polytetrafluoroethylene liner and crystallized at 170°C for 72 hours. Then it was washed with deionized water until the filtrate was neutral. It was dried at 60°C for 12 hours and then calcined at 550°C for 6 hours to obtain titanium silicon molecular sieve TS-1 nanosheets. The structure and crystallinity of the prepared titanium-silicon molecular sieve TS-1 nanosheet crystals (MFI) remained unchanged, and the morphology was sheet-like. The cyclohexanone ammoniation reaction of titanium-silicon molecular sieve TS-1 nanosheets includes the following steps: S1. 0.075g of catalyst titanium silicate molecular sieve TS-1 nanosheets, 0.196g of cyclohexanone, 7.5g of water, 5.9g of tert-butanol, 0.561g of NH3·H2O and 0.227g of H2O2 were added to a flask. The NH3·H2O was 25wt% and the H2O2 was 30wt%. The flask was heated to 80℃ and kept at that temperature for 3h. After the reaction was completed, it was cooled to room temperature in an ice-water bath to obtain cyclohexanone oxime. S2. Add 6g of ethanol and 0.15g of diethylene glycol monoethyl ether to the solution after the reaction, stir and mix well, and remove the catalyst by centrifugation; use diethylene glycol monoethyl ether as an internal standard, and detect it by gas chromatography using the internal standard method. Catalyst activity evaluation results: The conversion rate of cyclohexanone was 95.28%, and the selectivity for cyclohexanone oxime was 100%.

2. The method for preparing TS-1 nanosheets of titanium-silicon molecular sieve according to claim 1, characterized in that, The molar ratio of tetraethyl orthosilicate: tetrabutyl titanate: tetrapropylammonium hydroxide is 1:0.008~0.06:0.125~0.

35.

3. The method for preparing TS-1 nanosheets of titanium-silicon molecular sieve according to claim 1, characterized in that, The crystallization method is to heat at 110℃~170℃ for 24h~80h.

4. The method for preparing TS-1 nanosheets of titanium-silicon molecular sieve according to claim 1, characterized in that, The calcination conditions are: calcination at 550℃ for 5 to 7 hours.

5. A titanium-silicon molecular sieve TS-1 nanosheet prepared by the preparation method according to any one of claims 1 to 4.

6. The application of the titanium-silicon molecular sieve TS-1 nanosheets as described in claim 5 in the preparation of a catalyst for the ammoxidation of cyclohexanone to cyclohexanone oxime.

7. The application of the titanium-silicon molecular sieve TS-1 nanosheets according to claim 6 in the preparation of a catalyst for the ammoxidation of cyclohexanone to cyclohexanone oxime, characterized in that, Cyclohexanone oxime is prepared according to the following steps: Cyclohexanone oxime was obtained by mixing 30wt% H2O2 as oxidant, water as solvent, tert-butanol as co-solvent, and TS-1 titanium silicate molecular sieve nanosheets as catalyst. The mixture was kept at 60℃~80℃ for 1h~3h. After the reaction was completed, it was cooled to room temperature in an ice-water bath to obtain cyclohexanone oxime.

8. The application of the titanium-silicon molecular sieve TS-1 nanosheets according to claim 7 in the preparation of a catalyst for the ammoxidation of cyclohexanone to cyclohexanone oxime, characterized in that, The mass-to-molar ratio of TS-1 titanium-silicon molecular sieve nanosheets to cyclohexanone is 25g~32.5g:1mol.

9. The application of the titanium-silicon molecular sieve TS-1 nanosheets according to claim 7 in the preparation of a catalyst for the ammoxidation of cyclohexanone to cyclohexanone oxime, characterized in that, The molar ratio of cyclohexanone:water:tert-butanol:NH3·H2O:H2O2 is 1:44~237:14~44:1.5~8:1~2.

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