Titanium silicon molecular sieve and preparation method thereof, method for preparing cyclohexanone oxime, and method for preparing caprolactone

Abstract

The present invention relates to the technical field of cyclohexanone catalytic oxidation, and specifically to a titanium silicalite molecular sieve and a preparation method thereof, a method for preparing cyclohexanone oxime, and a method for preparing caprolactone. The method comprises: (1) uniformly mixing a silicon source, an alkaline template, a titanium source, and water to obtain a titanium silicalite sol; and (2) adding a silanization agent to the titanium silicalite sol, and hydrothermally crystallizing and calcining the obtained mixture. The present invention treats the titanium silicalite sol precursor with a specific silanization agent to prepare a titanium silicalite molecular sieve. When used in the catalytic oxidation of cyclohexanone and the ammoximation reaction of cyclohexanone, the titanium silicalite molecular sieve has high catalytic activity, and the conversion rate of cyclohexanone can be increased to above 91%.

Description

Technical Field

[0001] The present invention relates to the technical field of cyclohexanone catalytic oxidation and ammoximation, and in particular to a titanium silicon molecular sieve and a preparation method thereof, a method for preparing cyclohexanone oxime, and a method for preparing caprolactone. Background Art

[0002] Fine chemicals have attracted widespread attention from researchers in the chemical industry due to their high added value and wide range of applications. With the rapid development of society, the demand for fine chemicals has also increased. Among them, caprolactone, as an important organic chemical intermediate, has undergone a long research phase in its production and development. Caprolactone is a colorless liquid with an aromatic odor. It is easily soluble in water, ethanol, benzene, and other substances, but insoluble in petroleum ether. Degradable plastics prepared from caprolactone have excellent biocompatibility and biodegradability, and have broad application prospects in fields such as biomedicine, plastic tableware, and ground film materials, meeting the current needs of green development. Caprolactone can also be used as a synthetic raw material for automotive primers, adhesives, cast elastomers, etc. In addition, cyclohexanone oxime is a white prismatic crystal that is soluble in solvents such as water, ethanol, and methanol, and is an intermediate in the production of caprolactam.

[0003] Currently, caprolactone can be prepared via the Baeyer-Villiger oxidation method, hexanediol dehydrogenation, and intramolecular condensation of 6-hydroxyhexanoic acid. The Baeyer-Villiger oxidation of cyclohexanone with peroxycarboxylic acid is the primary method used industrially to prepare caprolactone. However, using peroxyacids as both oxidants and catalysts has numerous drawbacks: They generate large amounts of organic carboxylic acid waste, causing severe environmental pollution; the products are difficult to purify and separate, resulting in poor atom economy; and the production of organic peroxyacids requires the use of highly concentrated hydrogen peroxide, which is unstable and dangerous to transport. Therefore, researchers are using hydrogen peroxide as an oxidant instead of peroxyacids. When hydrogen peroxide is involved in the reaction, the only byproduct is water, and the active oxygen utilization rate is high. Hydrogen peroxide oxidant, combined with titanium silicalite catalysts, can form an excellent Ti-OOH catalytic oxidation system.

[0004] The traditional industrial production of cyclohexanone oxime uses the hydroxylamine process, which requires hydroxylamine and large amounts of sulfuric acid, resulting in severe environmental pollution. Researchers at home and abroad have conducted extensive research to improve this process and have discovered that the use of titanium silicate molecular sieves to catalyze the production of cyclohexanone oxime from cyclohexanone offers advantages such as mild reaction conditions and a low number of byproducts. Titanium silicate molecular sieves are molecular sieves formed by replacing silicon atoms with a small number of titanium atoms within a tetrahedral framework. The framework titanium atoms serve as catalytically active centers, playing a crucial role in the catalytic reaction.

[0005] CN107840344A discloses a titanium silicate molecular sieve, its preparation method and application. A certain proportion of mesoporous channels can be introduced into the titanium silicate molecular sieve through treatment with a silanization agent. However, the introduction of mesoporous channels may lead to the loss of some active centers of the skeleton titanium atoms, thereby affecting its catalytic oxidation activity of cyclohexanone. Summary of the Invention

[0006] The purpose of the present invention is to improve the catalytic performance of titanium silicate in catalyzing cyclohexanone reaction and ammoximation, and to provide titanium silicate and its preparation method, as well as a method for preparing cyclohexanone oxime and a method for preparing caprolactone.

[0007] In order to achieve the above object, the first aspect of the present invention provides a method for preparing titanium silicate molecular sieve, the method comprising:

[0008] (1) uniformly mixing a silicon source, an alkaline template, a titanium source, and water to obtain a titanium silicate sol;

[0009] (2) adding the compound represented by formula (I) to the titanium silicalite, and subjecting the obtained mixture to hydrothermal crystallization and calcination;

[0010]

[0011] wherein i is an integer from 1 to 10; R1, R2 and R3 are each independently selected from a C1-C6 alkyl group, and R4 is selected from a C1-C6 alkyl group or hydrogen.

[0012] The second aspect of the present invention provides a titanium silicate molecular sieve prepared according to the method described in the first aspect.

[0013] A third aspect of the present invention provides a method for preparing cyclohexanone oxime, comprising: contacting cyclohexanone, alcohol, aqueous ammonia and hydrogen peroxide in the presence of a catalyst for reaction, wherein the catalyst comprises the titanium silicalite described in the second aspect.

[0014] A fourth aspect of the present invention provides a method for preparing caprolactone, comprising: contacting cyclohexanone, alcohol and hydrogen peroxide in the presence of a catalyst for reaction, wherein the catalyst comprises the titanium silicalite described in the second aspect.

[0015] Through the above technical solution, the present invention treats the titanium silicalite precursor with a specific silanization reagent, and the prepared titanium silicalite molecular sieve has high catalytic activity when used for catalytic oxidation of cyclohexanone, and can increase the conversion rate of cyclohexanone to more than 91%. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is the XRD pattern of the titanium silicate molecular sieve obtained in Example 1 of the present invention;

[0017] Figure 2 is the UV-Vis spectrum of the titanium silicate molecular sieve obtained in Example 1 of the present invention;

[0018] Figure 3 This is a TEM image of the titanium silicate molecular sieve obtained in Example 1 of the present invention;

[0019] Figure 4 This is the XRD pattern of the titanium silicon molecular sieve obtained in Comparative Example 1;

[0020] Figure 5 is the XRD pattern of the titanium silicate molecular sieve obtained in Example 21 of the present invention;

[0021] Figure 6 This is the UV-Vis spectrum of the titanium silicate molecular sieve obtained in Example 21 of the present invention. DETAILED DESCRIPTION

[0022] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0023] As mentioned above, the first aspect of the present invention provides a method for preparing titanium silicate molecular sieve, the method comprising:

[0024] (1) uniformly mixing a silicon source, an alkaline template, a titanium source, and water to obtain a titanium silicate sol;

[0025] (2) adding the compound represented by formula (I) to the titanium silicalite, and subjecting the obtained mixture to hydrothermal crystallization and calcination;

[0026]

[0027] wherein i is an integer from 1 to 10; R1, R2 and R3 are each independently selected from a C1-C6 alkyl group, and R4 is selected from a C1-C6 alkyl group or hydrogen.

[0028] In the present invention, C1-C6 alkyl refers to an alkyl group having 1 to 6 carbon atoms, for example, it can be one of methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl and n-hexyl.

[0029] In some preferred embodiments of the present invention, i is an integer of 1-5, for example, 1, 2, 3, 4 or 5.

[0030] In some preferred embodiments of the present invention, R1, R2, and R3 are each independently selected from a C1-C3 alkyl group, wherein the C1-C3 alkyl group may be a methyl group, an ethyl group, an n-propyl group, or an isopropyl group. Preferably, R1, R2, and R3 are each independently selected from a methyl group, an ethyl group, or an n-propyl group. In the present invention, R1, R2, and R3 may be the same or different. Preferably, R1, R2, and R3 are the same.

[0031] According to the present invention, under preferred conditions, R4 is selected from one of hydrogen, methyl, ethyl or n-propyl.

[0032] In the present invention, the prepared titanium silicate molecular sieve has a fully microporous structure through the hydrogen bonding force between the amino groups of multiple silanization reagents and the flexible force of the external single-chain alkyl group (R4) connected to the amino group, and can also significantly increase the micropore volume and specific surface area of ​​the titanium silicate molecular sieve.

[0033] According to the present invention, if the amount of the silanization agent (the compound shown in formula (I)) is too high, the crystallization performance of the titanium silical sol will deteriorate and the skeleton structure of the molecular sieve will contain more defects; and if the amount of the silanization agent (the compound shown in formula (I)) is too low, the specific surface area of ​​the obtained titanium silicalite molecular sieve will be reduced, affecting its catalytic activity in cyclohexanone. Under preferred conditions, in step (1), the silicon source is calculated as SiO2, and the molar ratio of the silicon source to the compound shown in formula (I) is 1: (0.01-0.3), preferably 1: (0.01-0.2); more preferably 1: (0.05-0.2).

[0034] In some preferred embodiments of the present invention, the silicon source is calculated as SiO2, the alkaline template is calculated as N when it contains nitrogen, and as OH when it does not contain nitrogen. - The molar ratio of the silicon source, the alkaline template and water is 1: (0.05-0.4): (5-40); preferably 1: (0.1-0.3): (5-25).

[0035] According to the present invention, under preferred conditions, the silicon source is selected from at least one of tetramethyl silicate, tetraethyl silicate, tetrapropyl silicate, tetrabutyl silicate, silica gel, white carbon black and silica sol;

[0036] According to the present invention, under preferred conditions, the alkaline template is selected from at least one of quaternary ammonium bases, aliphatic amines and aliphatic alcoholamines, preferably at least one of tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide and tetrabutylammonium hydroxide;

[0037] In some preferred embodiments of the present invention, the silicon source is calculated as SiO2, the titanium source is calculated as TiO2, and the molar ratio of the silicon source to the titanium source is 1:(0.001-0.04), preferably 1:(0.005-0.025).

[0038] According to the present invention, under preferred conditions, the titanium source is selected from an organic titanium source and / or an inorganic titanium source; further preferably, the titanium source is selected from at least one of titanium tetrachloride, titanium sulfate, titanium nitrate, tetraethyl titanate, tetrapropyl titanate and tetrabutyl titanate.

[0039] In a preferred embodiment of the present invention, step (1) further comprises: mixing a silicon source, an alkaline template, and water, and stirring the mixture at room temperature for a first time for 0.1-2 hours, then adding a titanium source during the stirring process, and stirring the mixture for a second time for 0.5-6 hours to obtain a titanium silicalite. Under preferred conditions, the second stirring time is 0.5-3 hours.

[0040] According to the present invention, under preferred conditions, step (1) further comprises: driving out the alcohol after the mixing; driving out the alcohol can remove the alcohol generated by the hydrolysis of the silicon source and the titanium source. In the present invention, the alcohol generated in the system is preferably removed by azeotropic distillation, and the water lost by azeotropic distillation is supplemented during the driving out of the alcohol to ensure that the ratio of each substance in the titanium silicalite meets the above requirements; preferably, the conditions for driving out the alcohol include: temperature of 30-100°C and time of 2-10h; more preferably: temperature of 40-90°C and time of 4-10h.

[0041] According to the present invention, in order to enable the silanization agent (the compound represented by formula (I)) to be uniformly dispersed in the titanium silica sol, under preferred conditions, step (1) further comprises: adding the compound represented by formula (I) to the titanium silica sol and performing a third stirring for 0.1-24 hours, preferably the third stirring time is 0.5-10 hours, more preferably 0.5-5 hours.

[0042] The inventors of the present invention have found that if the hydrothermal time is too long, the crystallinity of the molecular sieve will be improved, but the specific surface area of ​​the molecular sieve will decrease; and if the hydrothermal time is too short, the skeleton structure of the molecular sieve will not grow perfectly. In some preferred embodiments of the present invention, in step (2), the conditions of the hydrothermal crystallization include: heating the mixture to 50-200 ° C within 0.1-1 h, and then crystallizing at 50-200 ° C for 10-100 h; preferably, crystallizing at a temperature of 100-200 ° C for 20-80 h; more preferably, the conditions of the hydrothermal crystallization include: a temperature of 120-180 ° C and a time of 20-80 h; under the above preferred conditions, the specific surface area and pore volume of the molecular sieve can be balanced; a molecular sieve with good crystallization, a specific specific surface area and a pore volume is prepared.

[0043] The present invention has no particular limitation on the pressure of hydrothermal crystallization, which may be the autogenous pressure of the crystallization system.

[0044] According to the present invention, under preferred conditions, the method further comprises: washing, filtering, and drying the product obtained by hydrothermal crystallization; wherein the washing, filtering, and drying processes are known to those skilled in the art. For example, the washing temperature can be 20-50°C, the washing solvent can be water, and the amount of the washing solvent used is 1-20 times the mass of the crystallized product; the drying conditions can be: temperature 40-150°C, and drying time 0.5-24 hours.

[0045] In some preferred embodiments of the present invention, the calcination conditions include: temperature of 400-800° C., time of 1-15 h; preferably temperature of 500-600° C., time of 4-10 h.

[0046] The second aspect of the present invention provides a titanium silicate molecular sieve prepared according to the method described in the first aspect.

[0047] According to the present invention, under preferred conditions, the pore size of the titanium silicate molecular sieve is 0.5-0.6 nm; the specific surface area is 550-650 m 2 / g; micropore volume is 0.2-0.3cm 3 / g.

[0048] In the present invention, the titanium silicalite molecular sieve can be used as a catalyst for cyclohexanone reactions, such as catalyzing the Baeyer-Villiger reaction of cyclohexanone to prepare caprolactone and the ammoximation reaction of cyclohexanone to prepare cyclohexanone oxime.

[0049] The third aspect of the present invention provides a method for preparing caprolactone, which comprises: contacting cyclohexanone, alcohol and hydrogen peroxide in the presence of a catalyst for reaction, wherein the catalyst comprises the titanium silicalite described in the second aspect; under preferred conditions, the reaction conditions include: the molar ratio of the titanium silicalite, cyclohexanone and alcohol is 1: (10-30): (50-150); preferably, the reaction conditions also include: temperature of 30-120°C and time of 2-8h.

[0050] According to the present invention, under preferred conditions, the alcohol is selected from C1-C6 alcohols, preferably at least one of methanol, ethanol and tert-butanol.

[0051] A fourth aspect of the present invention provides a method for preparing cyclohexanone oxime, comprising: contacting cyclohexanone, alcohol, aqueous ammonia and hydrogen peroxide in the presence of a catalyst for reaction, wherein the catalyst comprises the titanium silicalite described in the second aspect.

[0052] According to the present invention, under preferred conditions, the reaction conditions include: the weight ratio of titanium silicalite, alcohol and ammonia water is 1: (10-30): (10-30); the volume ratio of cyclohexanone and alcohol is 1: (1-5); further preferably, the reaction conditions also include: temperature of 30-120 ° C, time of 2-8h; more preferably, the alcohol is selected from C1-C6 alcohols, preferably at least one of methanol, ethanol and tert-butanol.

[0053] In the present invention, the catalyst may be a full molecular sieve or may contain a carrier; when used for catalytic oxidation of cyclohexanone and ammoximation of cyclohexanone, the titanium silicate molecular sieve particles are directly used as the catalyst.

[0054] According to a particularly preferred embodiment of the present invention, the method for preparing titanium silicate molecular sieve comprises:

[0055] (1) mixing a silicon source, an alkaline template, and water in a molar ratio of 1:(0.1-0.3):(5-25), stirring for a first time at room temperature for 0.1-2 hours, then adding a titanium source during the stirring process, and stirring for a second time for 0.5-3 hours to obtain a mixed system; wherein the molar ratio of the silicon source to the titanium source is 1:(0.005-0.025);

[0056] Then, the mixed system is subjected to alcoholization to obtain titanium silicalite; the alcoholization temperature is 40-90° C. and the time is 4-10 hours;

[0057] (2) adding the compound represented by formula (I) to the titanium silicalite sol and performing a third stirring for 1-3 hours, and performing hydrothermal crystallization and calcination on the obtained mixture; wherein the molar ratio of the silicon source to the compound represented by formula (I) is 1:(0.05-0.2), and the crystallization conditions are: heating the mixture to 150-180°C within 0.1-1 hour, and then performing hydrothermal crystallization at 150-180°C for 20-70 hours;

[0058]

[0059] wherein i is an integer from 1 to 10; R1, R2 and R3 are selected from methyl, ethyl, n-propyl, isopropyl, or n-butyl; and R4 is selected from hydrogen, methyl, ethyl, n-propyl, or isopropyl.

[0060] The present invention will be described in detail below through examples. In the following examples, room temperature refers to 25±5°C.

[0061] In the following examples and comparative examples, X-ray diffraction (XRD) phase diagrams of the samples were determined on a Siemens D5005 X-ray diffractometer, using a Cu Kα source at a tube voltage of 40 kV, a tube current of 40 mA, a scan rate of 0.5° / min, and a scan range of 2θ = 5°-35°. The UV-visible spectra (UV-Vis) of the samples were obtained using an Agilent Cary 300 UV spectrophotometer, with a wavelength interval of 3 nm and a scan range of 190-800 nm.

[0062] The specific surface area was obtained by measuring the static N2 adsorption-desorption curve of the sample at liquid nitrogen temperature (77.4K) using a Micromeritics ASAP2405J static nitrogen adsorption instrument, and then performing BET fitting on the adsorption curve in the range of P / P0=0.05-0.35;

[0063] The pore volume was determined according to the method described in RIPP 151-90 in Analytical Methods in Petrochemical Engineering compiled by Yang Cuiding et al. (Science Press, first edition, published in September 1990);

[0064] The pore size distribution was calculated according to the BJH formula;

[0065] The particle size was measured using a JEOL JEM-2100 transmission electron microscope (TEM).

[0066] In the following examples, the silanization agents used are shown in Table 1; wherein, Compounds 1 to 6 were all commercially available.

[0067] Table 1

[0068]

[0069] Example 1

[0070] (1) Tetrapropyl silicate, tetrapropylammonium hydroxide and water were stirred for a first time at room temperature for 0.5 h, and tetraethyl titanate was added during the stirring process and stirred for a second time for 1 h to obtain a mixed system; wherein tetrapropyl silicate was calculated as SiO2, tetrapropylammonium hydroxide was calculated as N, and tetraethyl titanate was calculated as TiO2, and the molar ratio of tetrapropyl silicate, tetrapropylammonium hydroxide, water and tetraethyl titanate was 1:0.25:10:0.02

[0071] Then, the mixed system was subjected to alcoholization at 80°C for 5 hours to obtain titanium silicalite;

[0072] (2) adding compound (1) to the titanium silicate sol, and stirring for a third time at room temperature for 1 hour to obtain a mixture, wherein the molar ratio of compound (1) to tetrapropyl silicate is 0.12:1;

[0073] (3) heating the mixture to 180°C for 0.8 h and performing hydrothermal crystallization at 180°C for 60 h to obtain a crystallized product;

[0074] The crystallized product was sequentially washed with water, filtered, and dried at 120 °C for 2 h;

[0075] The dried product was calcined at 550°C for 6 h to obtain titanium silicate molecular sieve;

[0076] The XRD spectrum of the titanium silicate molecular sieve obtained in this example is as follows: Figure 1 As shown, the UV-Vis spectrum is as follows Figure 2 As shown in the TEM image Figure 3 The physical parameters and catalytic performance are shown in Table 3. Figure 1 It can be seen that the titanium silicate molecular sieve prepared in this example has an MFI structure; Figure 2 This shows that the titanium silicate molecular sieve prepared in this example has a skeleton titanium active center; Figure 3 It can be seen that the particle size of the titanium silicate molecular sieve prepared in this example is about 100-200 nm.

[0077] Example 2-20

[0078] Titanium silicate molecular sieve was prepared according to the method of Example 1. The proportions and synthesis conditions are shown in Table 2. The physical properties and catalytic performance of the prepared molecular sieve are shown in Table 3.

[0079] Comparative Example 1

[0080] Titanium silicate molecular sieve was prepared according to the method for preparing titanium silicate micro-mesoporous molecular sieve composite material disclosed in "Zeolites, 1992, Vol. 12, pp. 943-950". The specific method is as follows:

[0081] Mix 22.5g of tetraethyl silicate, 7.0g of tetrapropylammonium hydroxide and 59.8g of deionized water evenly and hydrolyze at 60℃ for 1.0h. Then, slowly drip a solution consisting of 1.1g of tetrabutyl titanate and 5.0g of isopropanol into the above solution under vigorous stirring. Stir the mixture at 75℃ for 3h to obtain a clear and transparent colloid. Then transfer the colloid into a stainless steel closed reactor and crystallize it at a constant temperature of 170℃ for 72h to obtain conventional TS-1 molecular sieve. Its XRD analysis spectrum is as follows Figure 4 shown.

[0082] Comparative Examples 2-6

[0083] Titanium silicate molecular sieve was prepared according to the method of Example 1. The proportions and synthesis conditions are shown in Table 2. The physical properties and catalytic performance of the prepared molecular sieve are shown in Table 3.

[0084] Comparative Example 7

[0085] Titanium silicate molecular sieve was prepared according to the method of Example 1, except that the molecular structure of the silanization agent (Compound 7) was shown in Formula (II). The physical properties of the prepared molecular sieve are shown in Table 3.

[0086]

[0087] Comparative Example 8

[0088] Titanium silicate molecular sieve was prepared according to the method of Example 1, except that the silanization agent was N-phenyl-3-aminopropyltrimethoxysilane (Compound 8), whose structural formula is shown in Formula (III). The physical properties of the prepared molecular sieve are shown in Table 3.

[0089]

[0090] Test Example 1

[0091] This test example illustrates the reaction effect of the molecular sieves prepared in Examples 1-20 and Comparative Examples 1-8 provided by the present invention in catalyzing the Baeyer-Villiger reaction of cyclohexanone to prepare caprolactone. The reagents used in this test example are all commercially available chemically pure reagents. The concentrations of each substance after the reaction are quantitatively analyzed using gas chromatography. The gas chromatograph used is a 6890 model produced by Agilent; the analytical chromatographic column used is an FFAP column. The component concentrations are quantified using the external standard method. First, the peak area of ​​each component is measured, and the component concentration is obtained using the standard working curve to calculate each indicator.

[0092] In the test example, the cyclohexanone conversion rate and caprolactone selectivity were calculated according to the following formulas:

[0093] Cyclohexanone conversion rate % = (1-moles of cyclohexanone remaining after reaction / moles of cyclohexanone added before reaction) × 100%

[0094] Caprolactone selectivity % = moles of caprolactone after reaction / (moles of cyclohexanone added before reaction - moles of cyclohexanone remaining after reaction) × 100%

[0095] The titanium silicalite molecular sieves prepared in Examples 1-20 and Comparative Examples 1-8 were added to a three-necked flask containing cyclohexanone and methanol in a molar ratio of 1:20:100. After the temperature stabilized at the set point, hydrogen peroxide (30% by weight) was added, with a molar ratio of cyclohexanone to hydrogen peroxide (H2O2) of 1:1. The reaction was continued at 70°C and 0.1 MPa (normal pressure) for 3 hours, then the reaction was terminated. The catalyst was removed by filtration, and samples were collected for chromatographic analysis. The reaction results are shown in Table 3.

[0096] Table 3

[0097]

[0098]

[0099] As can be seen from Table 3, the titanium silicate molecular sieve obtained in the embodiment of the present invention has high Baeyer-Villiger reaction activity of cyclohexanone, wherein the conversion rate of cyclohexanone is as high as 98%, and the selectivity of caprolactone is as high as 98%.

[0100] Example 21

[0101] (1) Tetrabutyl silicate, tetrabutylammonium hydroxide, and water are stirred for a first time at room temperature for 0.5 h, and titanium tetrachloride is added during the stirring process, and stirred for a second time for 0.5 h to obtain a mixed system; wherein tetrabutyl silicate is calculated as SiO2, tetrabutylammonium hydroxide is calculated as N, and titanium tetrachloride is calculated as TiO2, and the molar ratio of tetrabutyl silicate, tetrabutylammonium hydroxide, water, and titanium tetrachloride is 1:0.1:15:0.005;

[0102] Then, the mixed system was subjected to alcoholization at 80°C for 6 hours to obtain titanium silicalite;

[0103] (2) adding compound (4) to the titanium silicate sol, and stirring for a third time at room temperature for 1.5 hours to obtain a mixture, wherein the molar ratio of compound (4) to tetrabutyl silicate is 0.12:1;

[0104] (3) heating the mixture to 170°C for 0.5 h and performing hydrothermal crystallization at 170°C for 24 h to obtain a crystallized product;

[0105] The crystallized product was sequentially washed with water, filtered, and dried at 120 °C for 2 h;

[0106] The dried product was calcined at 550°C for 6 h to obtain titanium silicate molecular sieve;

[0107] The XRD spectrum of the titanium silicate molecular sieve obtained in this example is as follows: Figure 5 As shown, the UV-Vis spectrum is as follows Figure 6 The physical properties are shown in Table 5; Figure 5 It can be seen that the titanium silicate molecular sieve prepared in this example has an MFI structure; Figure 6 This indicates that the titanium silicate molecular sieve prepared in this example has a skeleton titanium active center.

[0108] Examples 22-40

[0109] Titanium silicate molecular sieve was prepared according to the method of Example 21. The proportions and synthesis conditions are shown in Table 4. The physical properties and catalytic performance of the prepared molecular sieve are shown in Table 5.

[0110] Comparative Examples 9-13

[0111] Titanium silicate molecular sieve was prepared according to the method of Example 21. The proportions and synthesis conditions are shown in Table 4. The physical properties and catalytic performance of the prepared molecular sieve are shown in Table 5.

[0112] Test Example 2

[0113] This test example illustrates the reaction effect of using the molecular sieves prepared in Examples 21-40 and Comparative Examples 1 and 9-15 provided by the present invention for the ammoximation reaction of cyclohexanone to prepare cyclohexanone oxime. The reagents used in this test example are all commercially available chemically pure reagents. The concentrations of each substance after the reaction were quantitatively analyzed using gas chromatography. The gas chromatograph used was a 6890 gas chromatograph produced by Agilent; the analytical chromatographic column used was an FFAP column. The component concentrations were quantified using the external standard method. First, the peak area of ​​each component was measured, and the component concentration was obtained using the standard working curve to calculate each indicator.

[0114] In the test example, the cyclohexanone conversion rate and cyclohexanone oxime selectivity were calculated according to the following formulas:

[0115] Cyclohexanone conversion rate % = (1-moles of cyclohexanone remaining after reaction / moles of cyclohexanone added before reaction) × 100%

[0116] Cyclohexanone oxime selectivity (%) = moles of cyclohexanone oxime after reaction / (moles of cyclohexanone added before reaction - moles of cyclohexanone remaining after reaction) × 100%.

[0117] Take the titanium silicon molecular sieve prepared in Examples 21-40 and Comparative Examples 9-15 as catalysts, respectively, and stir and mix uniformly in a slurry bed according to a mass ratio of 1:10:10 of catalyst, tert-butyl alcohol, and ammonia (25 wt%), and then heat to 70°C. After the temperature stabilizes at 70°C, hydrogen peroxide (30 wt%) is added at a rate of 5mL / h, a mixture of cyclohexanone and tert-butyl alcohol (volume ratio of cyclohexanone and tert-butyl alcohol is 1:3) is added at a rate of 8mL / h, and an ammonia solution (25 wt%) is added at a rate of 5mL / h. The three materials are added simultaneously and continuously discharged at the corresponding speed. After the reaction stabilizes for 3h, sampling is performed for chromatographic analysis. The reaction results are shown in Table 5.

[0118] Table 5

[0119]

[0120]

[0121] As can be seen from Table 5, the titanium silicate molecular sieve prepared in the embodiment of the present invention has high cyclohexanone ammoximation reaction activity, the cyclohexanone conversion rate is as high as 98%, and the selectivity of cyclohexanone oxime is also as high as 98%.

[0122] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A method for preparing titanium silicon molecular sieve, characterized in that: The method comprises: (1) uniformly mixing a silicon source, an alkaline template, a titanium source and water to obtain a titanium silicate sol; (2) adding the compound represented by formula (I) to the titanium silicalite sol, and subjecting the obtained mixture to hydrothermal crystallization and calcination; Formula (I) wherein i is an integer from 1 to 10; R1, R2, and R3 are each independently selected from a C1-C6 alkyl group, and R4 is selected from hydrogen or a C1-C6 alkyl group; In step (2), the hydrothermal crystallization conditions include: heating the mixture to 100-200°C within 0.1-1h, and then crystallizing at 100-200°C for 20-80h; The titanium silicate molecular sieve prepared by the method has a pore size of 0.5-0.6 nm and a specific surface area of ​​550-650 m 2 / g; micropore volume is 0.2-0.3cm 3 / g.

2. The method according to claim 1, wherein i is an integer from 1 to 5.

3. The method according to claim 1, wherein R1, R2 and R3 are each independently selected from methyl, ethyl or propyl.

4. The method according to claim 1, wherein R4 is selected from hydrogen, methyl, ethyl or n-propyl.

5. The method according to any one of claims 1 to 4, wherein: The silicon source is calculated as SiO2, and the molar ratio of the silicon source to the compound represented by formula (I) is 1:(0.01-0.3).

6. The method according to claim 5, wherein: The silicon source is calculated as SiO2, and the molar ratio of the silicon source to the compound represented by formula (I) is 1:(0.05-0.2).

7. The method according to any one of claims 1 to 4, wherein: The silicon source is calculated as SiO2, the alkaline template is calculated as N when it contains nitrogen, and as OH when it does not contain nitrogen. - The titanium source is calculated as TiO2, The molar ratio of the silicon source, the alkaline template and water is 1:(0.05-0.4):(5-40); The molar ratio of the silicon source to the titanium source is 1:(0.001-0.04).

8. The method according to claim 7, wherein: The silicon source is calculated as SiO2, the alkaline template is calculated as N when it contains nitrogen, and as OH when it does not contain nitrogen. - The titanium source is calculated as TiO2, The molar ratio of the silicon source, the alkaline template and water is 1:(0.1-0.3):(5-25); The molar ratio of the silicon source to the titanium source is 1:(0.005-0.025).

9. The method according to any one of claims 1 to 4, wherein: The silicon source is selected from at least one of tetramethyl silicate, tetraethyl silicate, tetrapropyl silicate, tetrabutyl silicate, silica gel, white carbon black and silica sol.

10. The method according to any one of claims 1 to 4, wherein: The alkaline template is selected from at least one of quaternary ammonium base, aliphatic amine and aliphatic alcohol amine.

11. The method according to claim 10, wherein: The alkaline template agent is selected from at least one of tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide and tetrabutylammonium hydroxide.

12. The method according to any one of claims 1 to 4, wherein: The titanium source is selected from an organic titanium source and / or an inorganic titanium source.

13. The method according to claim 12, wherein: The titanium source is selected from at least one of titanium tetrachloride, titanium sulfate, titanium nitrate, tetraethyl titanate, tetrapropyl titanate and tetrabutyl titanate.

14. The method according to any one of claims 1 to 4, wherein: Step (1) also includes driving out the alcohol after the mixing; the conditions for driving out the alcohol include: temperature of 30-100° C. and time of 2-10 hours.

15. The method according to claim 14, wherein The conditions for driving out the alcohol include: temperature of 40-90° C. and time of 4-10 h.

16. The method according to any one of claims 1 to 4, wherein: The calcination conditions include: temperature of 400-800° C. and time of 1-15 hours.

17. A titanium silicate molecular sieve prepared according to the method according to any one of claims 1 to 16.

18. A method for preparing cyclohexanone oxime, the method comprising: In the presence of a catalyst, cyclohexanone, alcohol, aqueous ammonia and hydrogen peroxide are contacted to react, wherein the catalyst comprises the titanium silicalite according to claim 17.

19. The method according to claim 18, wherein The reaction conditions include: the weight ratio of titanium silicalite, alcohol and ammonia water is 1: (10-30): (10-30); the volume ratio of cyclohexanone and alcohol is 1: (1-5).

20. The method according to claim 18, wherein The reaction conditions also include: temperature of 30-120° C. and time of 2-8 h.

21. A method for preparing caprolactone, characterized in that: The method comprises: contacting cyclohexanone, alcohol and hydrogen peroxide in the presence of a catalyst to react, wherein the catalyst comprises the titanium silicalite according to claim 17.

22. The method according to claim 21, wherein The reaction conditions include: the molar ratio of titanium silicalite, cyclohexanone and alcohol is 1: (10-30): (50-150).

23. The method according to claim 21, wherein The reaction conditions also include: temperature of 30-120° C. and time of 2-8 h.

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