A thin-layer TS-1 nanosheet catalyst and a preparation method and application thereof

Abstract

This application provides a thin-layer TS-1 nanosheet catalyst, its preparation method, and its applications, relating to the field of molecular sieves. This application utilizes a seed-assisted method and a low-cost template agent. Slow crystallization helps reduce crystal size. With the synergistic regulation of urea and isopropanol, crystal growth along the b-axis is directionally suppressed, resulting in thin-layer TS-1 nanosheets with a thickness of approximately 100 nm. This method is simple, highly controllable, and suitable for industrial-scale production. The resulting catalyst, due to its short b-axis and structure, effectively improves mass transfer efficiency within the molecular sieve channels, reduces carbon deposition, and enhances the accessibility of titanium active sites, effectively improving conversion and selectivity in the ammonium oximeation of cyclohexanone. When a mesoporous template agent is further introduced to construct mesopores, the resulting catalyst possesses a multi-level structure combining micropores and mesopores, further enhancing its mass transfer capacity, improving its resistance to carbon deposition, and increasing its stability in use, showing broad prospects for industrial application.

Description

Technical Field

[0001] This application relates to the field of molecular sieves, and in particular to a thin-layer TS-1 nanosheet catalyst, its preparation method, and its application. Background Technology

[0002] Cyclohexanone oxime is a key intermediate in the synthesis of caprolactam, an important organic chemical raw material widely used in the production of nylon fibers and engineering plastics. The ammoniation of cyclohexanone is the mainstream process for its preparation. Traditional liquid-phase ammoniation processes typically use organic solvents as the reaction medium and employ homogeneous catalytic systems, which suffer from high energy consumption for solvent recovery, long separation processes, and heavy environmental burdens. In contrast, heterogeneous ammoniation reactions offer significant advantages such as being green, safe, and low-cost. However, the existing titanium-silicon molecular sieve TS-1 suffers from low mass transfer efficiency, poor accessibility of active sites, and easy carbon deposition and deactivation in heterogeneous systems, attracting widespread attention from academia and industry.

[0003] Titanium silicate molecular sieve TS-1 is one of the most thoroughly studied and maturely applied catalysts in the ammonium oximation reaction. However, conventional TS-1 crystals have an MFI topology, containing both ten-membered ring straight channels and intersecting sinusoidal channels. Molecular diffusion of the material mainly occurs along the straight channel direction. TS-1 crystals obtained under conventional synthesis conditions are often thicker along the b-axis, resulting in longer straight channels, longer molecular diffusion paths, and significant mass transfer resistance. This restricts the diffusion of reactants to active titanium sites in liquid-phase ammonium oximation reactions, especially in heterogeneous catalytic systems, making it difficult for products to move out of the channels. This leads to the aggregation of carbon precursors within the channels and side reactions, ultimately causing the catalyst to easily deactivate due to carbon deposition and reduced activity stability. Furthermore, when TS-1 crystals are large, a large number of active titanium sites are embedded inside the crystal lattice and difficult for reactants to access, resulting in poor accessibility of active sites and hindering the full utilization of catalyst activity.

[0004] Currently, several methods for preparing TS-1 nanosheets and sheet-like TS-1 have been disclosed. For example, patent CN119774627A discloses a method for urea-assisted synthesis of TS-1 nanosheets, but this method uses tetrapropylammonium hydroxide as a template agent, resulting in high catalyst preparation costs, which is not conducive to large-scale industrial production. Patent CN117401691A discloses a method for synthesizing sheet-like nanoscale TS-1, which also uses tetrapropylammonium hydroxide as a template agent, and still suffers from high costs. Patent CN118771408A discloses a method for preparing sheet-like TS-1 using crystallization mother liquor, which reduces the preparation cost to some extent, but the crystal size of the obtained sheet-like TS-1 is still relatively large, limiting the optimization effect on mass transfer efficiency and active site exposure. Summary of the Invention

[0005] In view of this, this application provides a thin-layer TS-1 nanosheet catalyst, its preparation method and application. The TS-1 nanosheet catalyst prepared by this application is low in cost and simple in process, and can solve the problems of low mass transfer efficiency, low catalytic activity, low selectivity and easy deactivation in the heterogeneous ammonium oxime reaction of cyclohexanone.

[0006] This application provides a method for preparing a thin-layer TS-1 nanosheet catalyst, comprising the following steps: Step 1: After mixing the first template agent, silicon source, titanium source, isopropanol and urea, seed crystals are obtained by crystallization, washing and calcination; Step 2: Mix the second template agent, silicon source, seed crystal described in Step 1, isopropanol, titanium source and urea, and then crystallize at a heating rate of 1℃ / h~30℃ / h from room temperature to 120℃~180℃ for 8 h~84 h. After washing and calcination, a thin-layer TS-1 nanosheet catalyst is obtained.

[0007] In some specific implementations, in step 1, the crystallization conditions are: heating from room temperature to 120℃~180℃ at a heating rate of 50℃ / h~80℃ / h for 24 h~72 h.

[0008] In some specific implementations, in step 1, the molar ratio of the silicon source (calculated as SiO2), titanium source (calculated as TiO2), first template agent, urea and isopropanol is 1:(0.01~0.05):(0.15~0.35):(0.05~0.65):(0.2~1.0).

[0009] In some specific implementations, in step 2, the molar ratio of the silicon source (calculated as SiO2), seed crystal, titanium source (calculated as TiO2), second template agent, urea and isopropanol is 1:(0.01~0.15):(0.01~0.05):(0.15~0.35):(0.05~0.65):(0.2~1.0).

[0010] In some specific implementations, the first template agent and the second template agent are each independently selected from tetrapropylammonium hydroxide or tetrapropylammonium bromide.

[0011] In some specific implementations, the first and second template agents are tetrapropylammonium bromide, and the addition of an alkaline source is also included; The alkaline source is one or more of ammonia, triethylamine, and ethylenediamine.

[0012] In some specific implementations, it also includes: adding a mesoporous template agent to step 2; The mesoporous template agent is one or more of hexadecyltrimethylammonium bromide, sodium dodecyl sulfonate, and sodium polyacrylate. The molar ratio of the silicon source (calculated as SiO2) to the mesoporous template agent is 1:(0.02~0.07).

[0013] In some specific implementations, in steps 1 and 2, the calcination temperature is 450℃~650℃, and the time is 4 h~7 h. This application also provides a thin-layer TS-1 nanosheet catalyst, obtained according to the preparation method of any of the above technical solutions.

[0014] This application also provides the application of a thin-layer TS-1 nanosheet catalyst prepared according to the preparation method described above, or the thin-layer TS-1 nanosheet catalyst described above, in the preparation of cyclohexanone oxime by amination of cyclohexanone.

[0015] This application provides a method for preparing a thin-layer TS-1 nanosheet catalyst, comprising the following steps: Step 1: Mixing a first template agent, a silicon source, a titanium source, isopropanol, and urea, followed by crystallization, washing, and calcination to obtain seed crystals; Step 2: Mixing a second template agent, a silicon source, the seed crystals obtained in Step 1, isopropanol, titanium source, and urea, and then crystallizing at a heating rate of 1℃ / h to 30℃ / h from room temperature to 120℃ to 180℃ for 8 h to 84 h, followed by washing and calcination to obtain a thin-layer TS-1 nanosheet catalyst. This preparation method, through a seed-assisted method and the use of an inexpensive template agent, effectively reduces production costs. Simultaneously, slow crystallization helps reduce crystal size, and with the synergistic regulation of urea and isopropanol, the growth of crystals along the b-axis is directionally suppressed, successfully producing thin-layer TS-1 nanosheets with a thickness of approximately 100 nm. This method is simple, highly controllable, and suitable for industrial-scale production. The prepared thin-layer TS-1 nanosheet catalyst, due to its short b-axis and structure, effectively improves the mass transfer efficiency within the molecular sieve channels, reduces carbon deposition, and enhances the accessibility of titanium active sites, thereby significantly improving conversion and selectivity in the ammonium oximeation of cyclohexanone. When a mesoporous template agent is further introduced to construct mesopores, the resulting catalyst possesses a multi-level structure combining micropores and mesopores, further strengthening its mass transfer capacity, enhancing its resistance to carbon deposition, and improving its stability in use, thus showing broad prospects for industrial application. Attached Figure Description

[0016] Figure 1 The X-ray diffraction pattern of Example 1; Figure 2 The X-ray diffraction pattern of Example 2; Figure 3 The X-ray diffraction pattern of Example 3; Figure 4 The X-ray diffraction pattern of Example 4; Figure 5 The X-ray diffraction pattern is shown in Comparative Example 1. Figure 6This is the X-ray diffraction pattern for Comparative Example 2; Figure 7 This is a scanning electron microscope image of Example 1; Figure 8 This is a scanning electron microscope image of Example 2; Figure 9 This is a scanning electron microscope image of Example 3; Figure 10 This is a scanning electron microscope image of Example 4; Figure 11 This is a scanning electron microscope image of Comparative Example 1; Figure 12 This is a scanning electron microscope image of Comparative Example 2. Detailed Implementation

[0017] It should be understood that the expression “one or more of…” individually includes each of the objects described after the expression, as well as various different combinations of two or more of the described objects, unless otherwise understood from the context and usage. The expression “and / or” combined with three or more described objects should be understood to have the same meaning, unless otherwise understood from the context.

[0018] The terms “including,” “having,” or “containing,” including the use of their grammatical synonyms, should generally be understood as open-ended and non-restrictive, for example, not excluding other unstated elements or steps, unless otherwise specifically stated or understood from the context.

[0019] It should be understood that the order of steps or the sequence of actions is not important as long as this application remains operational. Furthermore, two or more steps or actions can be performed simultaneously.

[0020] The use of any and all instances or exemplary language such as “e.g.” or “including” herein is merely intended to better illustrate the application and does not constitute a limitation on the scope of the application unless the claims are made. No language in this specification should be construed as indicating that any unclaimed element is essential to the practice of this application.

[0021] Furthermore, the numerical ranges and parameters used to define this application are approximate values, and the relevant values ​​in the specific embodiments have been presented as precisely as possible. However, any numerical value inevitably contains standard deviations due to individual test methods. Therefore, unless otherwise explicitly stated, it should be understood that all ranges, quantities, values, and percentages used in this disclosure are modified with the word "approximately." Here, "approximately" generally means that the actual value is within plus or minus 10%, 5%, 1%, or 0.5% of a specific value or range.

[0022] This application provides a method for preparing a thin-layer TS-1 nanosheet catalyst, comprising the following steps: Step 1: After mixing the first template agent, silicon source, titanium source, isopropanol and urea, seed crystals are obtained by crystallization, washing and calcination; Step 2: Mix the second template agent, silicon source, seed crystal described in Step 1, isopropanol, titanium source and urea, and then crystallize at a heating rate of 1℃ / h~30℃ / h from room temperature to 120℃~180℃ for 8 h~84 h. After washing and calcination, a thin-layer TS-1 nanosheet catalyst is obtained.

[0023] This application involves mixing a first template agent, a silicon source, a titanium source, isopropanol, and urea, followed by crystallization, washing, and calcination to obtain seed crystals.

[0024] Specifically, the first template agent is mixed with deionized water, a silicon source is added, and then isopropanol and a titanium source are added dropwise to the above mixed solution to obtain mixed solution A; urea is added to mixed solution A to obtain mixed solution B. Mixed solution B is transferred to a hydrothermal reactor for crystallization to obtain seed crystals. The seed crystals are then centrifuged, washed until neutral, dried, and calcined to obtain seed crystals.

[0025] This application does not impose any special restrictions on the sources of the first template agent, silicon source, titanium source, isopropanol, and urea, nor on the preparation method of mixed solution B, as long as the prepared mixed solution B is a homogeneous solution. In some specific implementations, the first template agent is selected from tetrapropylammonium hydroxide or tetrapropylammonium bromide, preferably tetrapropylammonium hydroxide. In some specific implementations, the first template agent is tetrapropylammonium bromide, and the addition of an alkaline source is further included, wherein the alkaline source is one or more of ammonia, triethylamine, and ethylenediamine, and the pH of the solution after adding the alkaline source is 7-9. In some specific implementations, the silicon source is one or more of tetraethyl silicate, silica sol, and silica, preferably tetraethyl silicate. In some specific implementations, the titanium source is one or more of tetrabutyl titanate, titanium tetrachloride, and titanium trichloride, preferably tetrabutyl titanate. In some specific implementations, the titanium source is preferably added slowly dropwise. In some specific implementations, the molar ratio of the silicon source (calculated as SiO2), titanium source (calculated as TiO2), first template agent, urea and isopropanol is 1:(0.01~0.05):(0.2~0.3):(0.1~0.6):(0.2~1.0).

[0026] In some specific implementations, the preparation of the first template agent solution, mixed solution A, and mixed solution B is preferably carried out under stirring conditions, and the stirring time is 1 h to 18 h, preferably 2 h to 12 h, and more preferably 1 h to 6 h. In some specific implementations, the crystallization is carried out by heating from room temperature to 120 h to 180 h at a heating rate of 50 h to 80 h for 24 h to 72 h. The crystallization process described in this application includes, but is not limited to, static, rotation, stirring, etc., any method known to those skilled in the art. In some specific implementations, the crystallization time is preferably 24 h to 48 h, more preferably 40 h to 50 h. This application does not have any special limitations on washing and drying, any method known to those skilled in the art is acceptable. In some specific implementations, the drying temperature is 60 h to 120 h, preferably 80 h to 100 h. In some specific implementations, the drying time is 4 h to 16 h, preferably 6 h to 12 h. In some specific implementations, the calcination temperature is 450℃~650℃, preferably 520℃~580℃. In some specific implementations, the calcination time is 4 h~7 h, preferably 4 h~6 h.

[0027] After obtaining the seed crystal, this application mixes the second template agent, silicon source, seed crystal, isopropanol, titanium source and urea, and then crystallizes the mixture from room temperature to 120℃~180℃ at a heating rate of 1℃ / h~30℃ / h for 8 h~84 h. The crystallized product is centrifuged, washed until neutral, and calcined to obtain a thin-layer TS-1 nanosheet catalyst.

[0028] Specifically, after obtaining the seed crystal, this application mixes the second template agent with deionized water, then adds a silicon source, the seed crystal, isopropanol, and a titanium source to obtain a mixed solution C. Urea is then added to mixed solution C to obtain mixed solution D. Mixed solution D is transferred to a hydrothermal reactor and crystallized at a heating rate of 1℃ / h to 30℃ / h from room temperature to 120℃ to 180℃ for 8 h to 84 h. The crystallized product is centrifuged, washed until neutral, and calcined to obtain a thin-layer TS-1 nanosheet catalyst.

[0029] This application does not impose any special restrictions on the sources of the second template agent, silicon source, titanium source, isopropanol, and urea, nor on the preparation method of the mixed solution D, as long as the prepared mixed solution D is a homogeneous solution. In some specific implementations, the second template agent is selected from tetrapropylammonium hydroxide or tetrapropylammonium bromide, preferably tetrapropylammonium bromide. In some specific implementations, the second template agent is tetrapropylammonium bromide, and the addition of an alkaline source is also included, wherein the alkaline source is one or more of ammonia, triethylamine, and ethylenediamine, and the pH of the solution after adding the alkaline source is 7-9. In some specific implementations, the silicon source is one or more of tetraethyl silicate, silica sol, and silica fume, preferably tetraethyl silicate. In some specific implementations, the titanium source is one or more of tetrabutyl titanate, titanium tetrachloride, and titanium trichloride, preferably tetrabutyl titanate. In some specific implementations, the titanium source is preferably added slowly dropwise. In some specific implementations, the molar ratio of the silicon source (based on SiO2), seed crystal, titanium source (based on TiO2), second template agent, urea, and isopropanol is 1:(0.01~0.15):(0.01~0.05):(0.15~0.35):(0.05~0.65):(0.2~1.0), preferably 1:(0.01~0.1):(0.01~0.04):(0.2~0.3):(0.1~0.6):(0.3~0.6). In some specific implementations, a mesoporous template agent is added to the second template agent solution. The mesoporous template agent is one or more of hexadecyltrimethylammonium bromide (CTAB), sodium dodecyl sulfonate (SDS), and sodium polyacrylate (PAAS), preferably hexadecyltrimethylammonium bromide (CTAB). In some specific implementations, the molar ratio of the silicon source (calculated as SiO2) to the mesoporous template agent is 1:(0.01~0.1), preferably 1:(0.02~0.07).

[0030] In some specific implementations, the preparation of the second template agent solution, mixed solution C, and mixed solution D is preferably carried out under stirring conditions, with a stirring time of 1 h to 18 h, preferably 2 h to 12 h, and more preferably 1 h to 6 h. The crystallization process described in this application includes, but is not limited to, static, rotational, and stirring methods, which are well known to those skilled in the art. In some specific implementations, the crystallization time is preferably 36 h to 64 h, more preferably 40 h to 50 h. This application does not have any special limitations on washing and drying; methods well known to those skilled in the art are acceptable. In some specific implementations, the drying temperature is 60℃ to 120℃, preferably 80℃ to 100℃. In some specific implementations, the drying time is 4 h to 16 h, preferably 6 h to 12 h. In some specific implementations, the calcination temperature is 450℃ to 650℃, preferably 520℃ to 580℃. In some specific implementations, the calcination time is 4 h to 7 h, preferably 4 h to 6 h.

[0031] This application effectively reduces production costs through a seed-assisted method and the use of inexpensive template agents (such as tetrapropylammonium bromide). Slow crystallization helps reduce crystal size, and by leveraging the synergistic regulation of urea and isopropanol, crystal growth along the b-axis is directionally suppressed, successfully producing thin-layer TS-1 nanosheets with a thickness of approximately 100 nm. Due to its extremely short b-axis thickness, this catalyst significantly improves the mass transfer efficiency within the molecular sieve channels, effectively reduces carbon deposition, and greatly enhances the accessibility of titanium active sites. When a mesoporous template agent is further introduced to construct mesopores, the resulting catalyst possesses a multi-level structure combining micropores and mesopores, further strengthening the mass transfer capacity of macromolecules and enhancing the catalyst's resistance to carbon deposition and its stability in use.

[0032] This application also provides a thin-layer TS-1 nanosheet catalyst, which is prepared according to any of the above technical solutions.

[0033] This application also provides the application of a thin-layer TS-1 nanosheet catalyst prepared according to the preparation method described above, or the thin-layer TS-1 nanosheet catalyst described above, in the preparation of cyclohexanone oxime by amination of cyclohexanone.

[0034] This application provides a method for preparing a thin-layer TS-1 nanosheet catalyst, comprising the following steps: Step 1: Mixing a first template agent, a silicon source, a titanium source, isopropanol, and urea, followed by crystallization, washing, and calcination to obtain seed crystals; Step 2: Mixing a second template agent, a silicon source, the seed crystals obtained in Step 1, isopropanol, titanium source, and urea, and then crystallizing at a heating rate of 1℃ / h to 30℃ / h from room temperature to 120℃ to 180℃ for 8 h to 84 h, followed by washing and calcination to obtain a thin-layer TS-1 nanosheet catalyst. This preparation method, through a seed-assisted method and the use of an inexpensive template agent, effectively reduces production costs. Simultaneously, slow crystallization helps reduce crystal size, and with the synergistic regulation of urea and isopropanol, the growth of crystals along the b-axis is directionally suppressed, successfully producing thin-layer TS-1 nanosheets with a thickness of approximately 100 nm. This method is simple, highly controllable, and suitable for industrial-scale production. The prepared thin-layer TS-1 nanosheet catalyst, due to its short b-axis and structure, effectively improves the mass transfer efficiency within the molecular sieve channels, reduces carbon deposition, and enhances the accessibility of titanium active sites, thereby significantly improving conversion and selectivity in the ammonium oximeation of cyclohexanone. When a mesoporous template agent is further introduced to construct mesopores, the resulting catalyst possesses a multi-level structure combining micropores and mesopores, further strengthening its mass transfer capacity, enhancing its resistance to carbon deposition, and improving its stability in use, thus showing broad prospects for industrial application.

[0035] The present application is further illustrated below with reference to embodiments. The scope of protection of the present application is not limited to the following embodiments.

[0036] Example 1

[0037] Step 1: Mix 3.1 g of tetrapropylammonium hydroxide solution and 12.6 g of deionized water, stir for 10 min, add 8.0 g of tetraethyl silicate, stir for 2 h, add dropwise a mixture of 3.1 g of isopropanol and 0.8 g of tetrabutyl titanate, and stir for another 6 h to obtain mixed solution A. Add 0.2 g of urea to mixed solution A and stir for 2 h to obtain mixed solution B. Transfer mixed solution B to a hydrothermal reactor, heat from room temperature to 150 °C at a heating rate of 70 °C / h, and then crystallize at 150 °C for 36 h; centrifuge and wash the seed crystal product until neutral, dry at 80 °C for 6 h, and then calcine at 500 °C for 4 h to obtain seed crystals.

[0038] Step 2: Mix 14.0 g of tetrapropylammonium hydroxide with 50.5 g of deionized water and stir for 10 min. Add 20.0 g of tetraethyl silicate and 0.6 g of seed crystals, stir for 3 h, and then add dropwise a mixture of 2.5 g of isopropanol and 1.2 g of tetrabutyl titanate. Stir for another 6 h to obtain mixed solution C. Add 2.1 g of urea to mixed solution C and stir for 3 h to obtain mixed solution D. Transfer mixed solution D to a hydrothermal reactor and heat it from room temperature to 170 °C at a heating rate of 12 °C / h. Crystallize at 170 °C for 48 h. Centrifuge and wash the crystallized product until neutral, dry it at 100 °C for 12 h, and then calcine it at 550 °C for 4 h to obtain a thin-layer TS-1 nanosheet catalyst.

[0039] Example 2

[0040] Step 1: Same as Step 1 in Example 1.

[0041] Step 2: Mix 5.0 g tetrapropylammonium bromide with 51.1 g deionized water, stir for 10 min, add 20.0 g tetraethyl silicate and 0.6 g seed crystals, adjust the pH to 8 with ammonia, stir for 3 h, add a mixture of 2.5 g isopropanol and 1.2 g tetrabutyl titanate dropwise, stir for another 6 h to obtain mixed solution C. Add 1.5 g urea to mixed solution C, stir for 3 h to obtain mixed solution D. Transfer mixed solution D to a hydrothermal reactor, heat from room temperature to 170 °C at a rate of 12 °C / h, and then crystallize at 170 °C for 48 h; centrifuge and wash the crystallized product until neutral, dry at 100 °C for 12 h, and then calcine at 550 °C for 4 h to obtain thin-layer TS-1 nanosheet catalyst. Figure 3 It is evident that the sample exhibits good crystallinity.

[0042] Example 3

[0043] Step 1: Same as Step 1 in Example 1.

[0044] Step 2: The difference from Step 2 in Example 2 is that 0.7 g of titanium tetrachloride was added as the titanium source. A thin-layer TS-1 nanosheet catalyst was obtained.

[0045] Example 4

[0046] Step 1: Same as Step 1 in Example 1.

[0047] Step 2: The difference from Step 2 in Example 2 is that 1.7 g of CTAB was added. This yielded a mesoporous thin-layer TS-1 nanosheet catalyst.

[0048] Comparative Example 1

[0049] 12.1 g of tetrapropylammonium hydroxide was mixed with 45.2 g of deionized water and stirred for 10 min. Then, 22.1 g of tetraethyl silicate was added and stirred for 3 h. Finally, 1.2 g of tetrabutyl titanate was added dropwise to obtain a mixed solution. The mixed solution was transferred to a hydrothermal reactor and crystallized at 180 °C for 48 h. The crystallized product was centrifuged, washed until neutral, dried at 100 °C for 12 h, and then calcined at 550 °C for 4 h to obtain titanium-silicon molecular sieve TS-1.

[0050] Comparative Example 2

[0051] Step 1: Same as Step 1 in Example 1.

[0052] Step 2: The difference from Step 2 of Example 2 is that the mixed solution D is transferred to a hydrothermal reactor and heated from room temperature to 170°C at a heating rate of 70°C / h.

[0053] Experimental Example 1

[0054] X-ray diffraction tests were performed on the TS-1 nanosheet catalysts obtained in Examples 1-4, Comparative Examples 1 and 2 above. The test results are shown in [reference needed]. Figures 1-6 . Figure 1 The image shows the XRD pattern of the TS-1 nanosheet catalyst prepared in Example 1. Figure 2 The image shows the XRD pattern of the TS-1 nanosheet catalyst prepared in Example 2. Figure 3 The image shows the XRD pattern of the TS-1 nanosheet catalyst prepared in Example 3. Figure 4 The image shows the XRD pattern of the TS-1 nanosheet catalyst prepared in Example 4. Figure 5 The image shows the XRD pattern of the TS-1 nanosheet catalyst prepared in Comparative Example 1. Figure 6 The image shows the XRD pattern of the TS-1 nanosheet catalyst prepared in Comparative Example 2.

[0055] Depend on Figures 1-6 It can be seen that the samples obtained in Examples 1-4, Comparative Example 1 and Comparative Example 2 have good crystallinity.

[0056] Experimental Example 2

[0057] The TS-1 nanosheet catalysts obtained in Examples 1-4, Comparative Example 1, and Comparative Example 2 were subjected to scanning electron microscopy tests. The test results are shown in [reference needed]. Figures 7-12 . Figure 7 This is a SEM image of the TS-1 nanosheet catalyst prepared in Example 1. Figure 8 This is a SEM image of the TS-1 nanosheet catalyst prepared in Example 2. Figure 9 This is a SEM image of the TS-1 nanosheet catalyst prepared in Example 3. Figure 10 This is a SEM image of the TS-1 nanosheet catalyst prepared in Example 4. Figure 11The image shows a SEM image of the TS-1 nanosheet catalyst prepared in Comparative Example 1. Figure 12 SEM image of the TS-1 nanosheet catalyst prepared in Comparative Example 2.

[0058] Depend on Figure 7 It can be seen that the sample prepared in Example 1 is sheet-like, with a b-axis dimension of approximately 100 nm. From Figure 8 It can be seen that the sample prepared in Example 2 is sheet-like, with a b-axis dimension of approximately 100 nm and a c-axis dimension of approximately 500 nm. From Figure 9 It can be seen that the sample prepared in Example 3 is sheet-like, with a b-axis dimension of approximately 100 nm. From Figure 10 It can be seen that the sample prepared in Example 4 is sheet-like, with a b-axis dimension of approximately 100 nm. From Figure 11 It can be seen that the sample prepared in Comparative Example 1 is spherical with a diameter of approximately 250 nm. Figure 12 It can be seen that the sample prepared in Comparative Example 2 is plate-shaped, with a b-axis size of about 200 nm and a c-axis size of about 800 nm. The overall grain size is larger than that of the sample prepared in Example 2.

[0059] Experimental Example 3

[0060] The homogeneous ammoniation of cyclohexanone was carried out using the thin-layer TS-1 nanosheet catalysts obtained in Examples 1-4, Comparative Examples 1 and 2 above. The specific method is as follows: In a 250 mL flask, 2.2 g of titanium silicate molecular sieve, 12 g of tert-butanol, and 2.1 g of water were added in one batch. After the temperature was raised to 76 °C, high-purity ammonia gas was added using a rotor flowmeter (flow rate 90 mL / min). Cyclohexanone was added continuously at a rate of 12 g / h, tert-butanol at a rate of 24 g / h, water at a rate of 4.2 g / h, and 30% hydrogen peroxide at a rate of 16.6 g / h. Samples were taken every 1.5 h, and the conversion rate and selectivity of cyclohexanone were detected by gas chromatography. The test results are shown in Table 1. The experimental results show that the thin-layer TS-1 nanosheet catalyst prepared in this application can effectively improve the conversion rate and selectivity of cyclohexanone ammoniation in homogeneous ammoniation and delay catalyst deactivation.

[0061] Table 1

[0062] Test Example 4

[0063] The heterogeneous ammoniation reaction of cyclohexanone was carried out using the thin-layer TS-1 nanosheet catalysts obtained in Examples 1-4, Comparative Examples 1 and 2 above. The specific method is as follows: 1.0 g of titanium silicate molecular sieve and 10.0 g of water were added simultaneously to a 50 mL flask. After the temperature was raised to 86 °C, high-purity ammonia gas was added using a rotor flowmeter (flow rate 120 mL / min). Cyclohexanone was added continuously at a rate of 9.7 g / h, tert-butanol at a rate of 24 g / h, and 30% hydrogen peroxide at a rate of 12.6 g / h. Samples were taken every 1.5 h, and the conversion rate and selectivity of cyclohexanone were detected by gas chromatography. The test results are shown in Table 2. The experimental results show that the thin-layer TS-1 nanosheet catalyst prepared in this application can effectively improve the conversion rate and selectivity of cyclohexanone amination and oxime reaction, and delay catalyst deactivation.

[0064] Table 2

[0065] The above description is merely a preferred embodiment of this application, but the scope of protection of this application is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in this application, based on the technical solution and inventive concept of this application, should be included within the scope of protection of this application.

Claims

1. A method for preparing a thin-layer TS-1 nanosheet catalyst, characterized in that, Includes the following steps: Step 1: After mixing the first template agent, silicon source, titanium source, isopropanol and urea, seed crystals are obtained by crystallization, washing and calcination; Step 2: Mix the second template agent, silicon source, seed crystal described in Step 1, isopropanol, titanium source and urea, and then crystallize at a heating rate of 1℃ / h~30℃ / h from room temperature to 120℃~180℃ for 8 h~84 h. After washing and calcination, a thin-layer TS-1 nanosheet catalyst is obtained.

2. The preparation method according to claim 1, characterized in that, The crystallization conditions in step 1 are as follows: the temperature is increased from room temperature to 120℃~180℃ at a heating rate of 50℃ / h~80℃ / h for 24 h~72 h.

3. The preparation method according to claim 1, characterized in that, In step 1, the molar ratio of the silicon source (calculated as SiO2), titanium source (calculated as TiO2), first template agent, urea and isopropanol is 1:(0.01~0.05):(0.15~0.35):(0.05~0.65):(0.2~1.0).

4. The preparation method according to claim 1, characterized in that, In step 2, the molar ratio of the silicon source (calculated as SiO2), seed crystal, titanium source (calculated as TiO2), second template agent, urea and isopropanol is 1:(0.01~0.15):(0.01~0.05):(0.15~0.35):(0.05~0.65):(0.2~1.0).

5. The preparation method according to claim 1, characterized in that, The first template agent and the second template agent are each independently selected from tetrapropylammonium hydroxide or tetrapropylammonium bromide.

6. The preparation method according to claim 5, characterized in that, The first and second template agents are tetrapropylammonium bromide, and an alkaline source is also added; The alkaline source is one or more of ammonia, triethylamine, and ethylenediamine.

7. The preparation method according to claim 1, characterized in that, Also includes: Add a mesoporous template agent to step 2; The mesoporous template agent is one or more of hexadecyltrimethylammonium bromide, sodium dodecyl sulfonate, and sodium polyacrylate. The molar ratio of the silicon source (calculated as SiO2) to the mesoporous template agent is 1:(0.01~0.1).

8. The preparation method according to claim 1, characterized in that, In steps 1 and 2, the calcination temperature is 450℃~650℃ and the time is 4 h~7 h.

9. A thin-layer TS-1 nanosheet catalyst, prepared by the preparation method according to any one of claims 1 to 8.

10. The application of the thin-layer TS-1 nanosheet catalyst prepared by the preparation method according to any one of claims 1 to 8 or the thin-layer TS-1 nanosheet catalyst according to claim 9 in the preparation of cyclohexanone oxime by amination of cyclohexanone.

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