Preparation method and application of epsilon-caprolactone catalyst prepared by cyclohexanone B-V oxidation

Abstract

The invention discloses a preparation method and application of an epsilon-caprolactone catalyst prepared by cyclohexanone B-V oxidation, and belongs to the technical field of catalysts. Heteropolyacid is introduced in the preparation process of the TS-1 molecular sieve, the heteropolyacid intervenes in the crystallization process of the TS-1 molecular sieve through an in-situ bonding method, one Si-O bond of tetra-coordinated Si in the TS-1 molecular sieve is opened, and the Si-O bond and a central atom in the heteropolyacid form a new chemical bond, so that the TS-1 molecular sieve is prepared. The effect that heteropolyacid uniformly and firmly grows on the pore channels and the surface of the TS-1 molecular sieve is achieved. According to the catalyst synthesized by the scheme, the original MFI topological structure of the TS-1 molecular sieve can be maintained, the large specific surface area of the catalyst is effectively ensured, the contact area of a catalytic system is increased, and the problem that heteropoly acid is difficult to separate in the catalytic system can be solved.

Description

Technical Field

[0001] The invention relates to the technical field of catalyst preparation, and in particular to a preparation method and application of a catalyst for preparing epsilon-caprolactone by oxidizing cyclohexanone BV. Background Art

[0002] ε-Caprolactone is a seven-membered cyclic lactone that is widely used in organic synthesis. It is usually polymerized with monomers such as glycolide, or self-polymerized to synthesize polymer materials such as polycaprolactone (PCL). PCL has many excellent properties, including thermoplasticity, permeability, deformation memory, biocompatibility and complete biodegradability, so it is widely used in environmentally friendly materials, biopharmaceuticals, medical devices and 3D printing. However, due to the difficulty of synthesizing ε-caprolactone and the problems of safety and product stability in the production process, my country currently relies mainly on imports. Therefore, it is of great significance to develop a synthetic process for ε-caprolactone. This can not only fill the domestic technical gap, but also bring huge economic benefits.

[0003] At present, the technical methods for synthesizing ε-caprolactone mainly include the Baeyer-Villiger oxidation of cyclohexanone, the adipic acid esterification and hydrogenation method, the catalytic dehydrogenation of 1,6-hexanediol and the condensation method of 6-hydroxycaproic acid. The Baeyer-Villiger oxidation of cyclohexanone is the most widely studied method. It is a method for oxidizing the readily available cyclohexanone into more complex and valuable esters and lactones. The Baeyer-Villiger oxidation of cyclohexanone can be divided into different types according to the type of oxidant: H2O2 oxidation, peroxyacid oxidation, O2 / air oxidation and biological oxidation. The peroxyacid oxidation method is a method with a long history and wide application. Although the process is relatively mature, it is easy to produce explosive peroxides and acidic byproducts. Although the O2 / air oxidation method and the biological oxidation method are relatively clean processes, the reaction yield is not high due to the low activity of molecular oxygen. In addition, it is difficult to find suitable biological enzymes and microorganisms in the biological method. It is still in the laboratory research and development stage. H2O2 oxidation is an environmentally friendly and green synthesis method, because it has a high content of active oxygen, and the oxidation products are only the target product and water. Therefore, using H2O2 as an oxidant to replace traditional peracids is an irreversible trend.

[0004] The catalysts commonly used in Baeyer-Villiger oxidation reactions are mainly divided into two categories: homogeneous catalysts and heterogeneous catalysts. Common homogeneous catalysts include metal complexes such as Re, Zr, Pt and W, while heterogeneous catalysts mainly include polymer-supported Pt, methyltrioxorhenium complexes, and Sn complexes supported by β zeolite, MCM-41, hydrotalcite, palygorskite, cellulose and montmorillonite. Among them, catalysts supported by Sn complexes have been studied the most and show excellent catalytic performance in the Baeyer-Villiger oxidation reaction of ketones; however, there are shortcomings such as limited acid strength of the active center Sn itself and complex catalyst preparation process. Therefore, it is very necessary to develop non-Sn-centered catalytic oxidation systems. As an environmentally friendly catalyst, heteropolyacids have attracted much attention in the field of catalysis in recent years due to their unique acidity and "quasi-liquid phase" characteristics. It is composed of heteroatoms (such as P, Si, Fe and Co) and polyatoms (such as Mo, W, V, Nb and Ta) in a certain structure through oxygen atom coordination bridge. It is a proton acid with uniform strength and has high catalytic activity and selectivity for nucleophilic addition-rearrangement type reactions. It is also environmentally friendly and is a promising green catalyst. However, heteropolyacids are difficult to recycle in homogeneous reactions and have a small specific surface area so that they cannot fully exert their catalytic performance.

[0005] TS-1 is an MFI molecular sieve with titanium atoms in its framework. Since it was reported in 1983, the study of its structure and catalytic performance has been one of the hot topics in the field of molecular sieves. The framework of TS-1 is composed of titanium oxide tetrahedron and silicon oxide tetrahedron, which are connected by oxygen bridges to form a basic structural unit of five-membered rings. The eight five-membered rings form a chain structure by sharing adjacent edges. The chain structure is connected into a mesh layer in three-dimensional space, thereby constructing a three-dimensional framework structure. The framework of TS-1 includes two mutually perpendicular channels, one is a straight channel parallel to the b axis with a pore size of 0.053nm×0.56nm; the other is a zigzag channel parallel to the c axis with a pore size of 0.51nm. The presence of framework titanium makes TS-1 have a stable framework structure and excellent catalytic activity, making it suitable as a carrier for heteropolyacid catalysts.

[0006] Therefore, the present invention aims to introduce heteropoly acid into the preparation process of TS-1 molecular sieve, and make the heteropoly acid intervene in the crystallization process of TS-1 molecular sieve through "in situ bonding method", so that TS-1 molecular sieve and heteropoly acid form new chemical bonds within a suitable time, so as to achieve the effect of heteropoly acid uniformly and firmly "growing" in the pores and surface of TS-1 molecular sieve, and prepare a new catalyst for preparing ε-caprolactone by oxidation of cyclohexanone BV. Summary of the invention

[0007] Based on previous research and existing problems, the present invention proposes a preparation method and application of a catalyst for preparing ε-caprolactone by oxidation of cyclohexanone BV after further research and analysis.

[0008] To achieve the above object, the present invention provides the following technical solutions:

[0009] A method for preparing a catalyst for preparing ε-caprolactone by oxidation of cyclohexanone BV, the specific method steps are as follows:

[0010] S1, preparing TS-1 precursor gel;

[0011] S2. preparing a heteropoly acid solution: adding a certain amount of heteropoly acid into deionized water and mixing evenly to obtain a heteropoly acid solution;

[0012] S3. Preparation of target catalyst by in-situ bonding method:

[0013] S31, adding the heteropoly acid solution into the TS-1 precursor gel at a certain rate by using a microinjector, and obtaining a mixed precursor sol after sufficient mixing;

[0014] S32, introducing the precursor gel into a polytetrafluoroethylene beaker, crystallizing it under autogenous pressure at a set temperature for a set time, then taking it out, washing it thoroughly with ethanol, drying it, and then calcining it to obtain the target catalyst;

[0015] S33, grinding and sieving the obtained target catalyst to 60-100 mesh.

[0016] Preferably, the preparation of TS-1 precursor gel in step S1 specifically includes:

[0017] S11, taking a certain amount of template agent and mixing it with deionized water for a period of time, using a micro-injector to drop a certain amount of silicon source into the alkali solution at a certain rate, and stirring at room temperature to fully hydrolyze it, which is recorded as solution A;

[0018] S12, taking a certain amount of titanium source and mixing it with isopropanol, and then putting it into an ultrasonic cleaner and shaking it thoroughly to make it fully mixed to form a solution B;

[0019] S13. Add solution B into solution A using a microinjector and stir evenly at room temperature to obtain a TS-1 precursor gel.

[0020] Preferably, it also includes:

[0021] S14. The obtained TS-1 precursor gel is stirred at room temperature using a magnetic stirrer, then aged at room temperature for a certain period of time, and de-alcoholized at a certain temperature for a certain period of time, and deionized water is continuously added to maintain a constant water content in the gel.

[0022] Preferably, the template is one or more of tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide (TEAOH), tetrapropylammonium hydroxide (TPAOH), tetrabutylammonium hydroxide (TBAOH), tetramethylammonium bromide (TMABr), tetraethylammonium bromide (TEABr), tetrapropylammonium bromide (TPABr) and tetrabutylammonium bromide (TBABr);

[0023] The silicon source is one or more of tetramethyl silicate (TMOS), tetraethyl silicate (TEOS), tetrapropyl silicate (TPOS) and tetrabutyl silicate (TBOS).

[0024] Preferably, the titanium source is one or more of tetraethyl titanate (TEOT), tetrabutyl titanate (TBOT), titanium tetrachloride (TiCl4), titanium tetrabromide (TiBr4) and titanium oxide (TiO2).

[0025] Preferably, the heteropoly acid is one or more of tungstophosphoric acid, molybdophosphoric acid, and silicotungstic acid.

[0026] Preferably, the template is tetrapropylammonium hydroxide, the silicon source is tetraethyl silicate, and the titanium source is tetrabutyl titanate. In S31, the molar composition of the mixed precursor sol is n(TEOS):n(TPAOH):n(TBOT):n(H2O)=1:0.10~0.20:0.10~0.20:20~100.

[0027] Preferably, in S32, the crystallization temperature is 120-170°C, the crystallization time is 24-96h, and the calcination temperature is 400-550°C.

[0028] The present invention also provides a catalyst for preparing ε-caprolactone by oxidizing cyclohexanone BV. The catalyst is prepared by the above-mentioned preparation method and is used for preparing ε-caprolactone by oxidizing cyclohexanone BV. The method is: cyclohexanone, hydrogen peroxide, an organic solvent and the synthesized catalyst are placed in a reactor for oxidation reaction to obtain ε-caprolactone.

[0029] Compared with the existing technology, the present invention provides a preparation method and application of a catalyst for preparing ε-caprolactone by oxidation of cyclohexanone BV, which has the following beneficial effects:

[0030] (1) The present invention introduces heteropoly acid into the preparation process of TS-1 molecular sieve, and makes the heteropoly acid intervene in the crystallization process of TS-1 molecular sieve through the "in situ bonding method". Within a suitable time, the TS-1 molecular sieve and the heteropoly acid form new chemical bonds, so that the heteropoly acid can be evenly and firmly "grown" in the pores and surface of the TS-1 molecular sieve. The synthesized catalyst can maintain the original MFI topological structure of the TS-1 molecular sieve, effectively ensuring that the catalyst has a larger specific surface area and increases the contact area of ​​the catalytic system, and can also maintain the structure of the heteropoly acid itself, ensuring the catalytic activity of the heteropoly acid.

[0031] (2) In addition, heteropolyacids are formed by heteroatoms (such as P, Si, Fe and Co, etc.) and polyatoms (such as Mo, W, V, Nb and Ta, etc.) coordinated and bridged by oxygen atoms in a certain structure. They are proton acids with uniform strength, high catalytic activity, good selectivity and no pollution to the environment. The skeleton of TS-1 is composed of titanium oxide tetrahedron and silicon oxide tetrahedron, which are connected by oxygen bridges to form a basic structural unit of a five-membered ring. Its Ti atoms are evenly distributed in the skeleton, providing L acid sites with uniform strength, and also have the characteristics of high chemical activity, good selectivity and no pollution to the environment. Through the "in-situ bonding method" in this invention, the Si-O bond in the molecular sieve can be connected with the MO bond (M is the central atom in the polyacid material) in the heteropolyacid, so that the heteropolyacid can be "grown" in the TS-1 molecular sieve skeleton while achieving the enhancement of B acid strength and the synergistic effect of B acid and L acid.

[0032] (3) The catalyst for preparing ε-caprolactone by oxidation of cyclohexanone BV synthesized by the present invention not only has abundant acidic sites and excellent catalytic activity, but also can maintain its original catalytic activity after multiple uses, and has the characteristics of a long service life, which can effectively reduce industrial production costs and meet the requirements of green industrial development. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a schematic diagram of the target catalyst structure obtained by the present invention;

[0034] Figure 2 The XRD pattern of the sample prepared in Example 1 is shown below;

[0035] Figure 3 FT-IR image of the sample prepared in Example 1;

[0036] Figure 4 This is the UV-vis image of the sample prepared in Example 1. DETAILED DESCRIPTION

[0037] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0038] Example 1

[0039] TS-1 precursor gel preparation:

[0040] 1) Take 12.69 g of tetrapropylammonium hydroxide and mix it thoroughly with 110 g of deionized water for 30 min. Use a microinjector to drop 35.04 g of tetraethyl silicate into the alkali solution at a rate of 20 mL / h. Use a magnetic stirrer to continuously stir for 3 to 6 h at room temperature to fully hydrolyze it. This is recorded as solution A.

[0041] 2) Take a certain amount of 1.42g of a mixed solution of tetrabutyl titanate and an appropriate amount of isopropyl alcohol, and put it into an ultrasonic cleaner and shake it for a period of time to make it fully mixed, which is recorded as solution B.

[0042] 3) Add solution B to solution A at a rate of 5 mL / h using a microinjector, and stir the mixture using a magnetic stirrer at room temperature for 1 to 3 h to obtain a TS-1 precursor gel without alcohol removal.

[0043] 4) The precursor gel was stirred at room temperature using a magnetic stirrer for 3 h, then aged at room temperature for 5 h, and de-alcoholized at 80° C. for 2 h, with deionized water continuously added to maintain a constant water content in the gel. After the de-alcoholization was completed, the TS-1 precursor gel was obtained for standby use.

[0044] Preparation of silicotungstic acid solution:

[0045] Take 1.2g of silicotungstic acid reagent and add it to 10.0g of deionized water, and put it into a magnetic stirrer to mix it thoroughly for 30 minutes to obtain a silicotungstic acid solution for standby use.

[0046] In-situ bonding method to prepare target catalyst:

[0047] 1) Using a microinjector, add the silicotungstic acid solution into the TS-1 precursor gel at a rate of 20 ml / h to obtain a mixed precursor sol.

[0048] 2) The precursor gel was introduced into a polytetrafluoroethylene beaker, crystallized under autogenous pressure at 170°C for 72 hours, and then taken out. After being fully washed with ethanol, it was dried in a forced air drying oven at 80°C overnight, and then calcined in a muffle furnace at 480°C for 6 hours, and the target catalyst was obtained after being taken out.

[0049] 3) The taken-out target catalyst is fully ground and sieved to 60-100 meshes to obtain a catalyst that can be used for the oxidation reaction of cyclohexanone BV to prepare ε-caprolactone.

[0050] Application Example 1

[0051] Take 4.8g cyclohexanone as raw material, 6.56g 30wt% hydrogen peroxide as oxidant, and appropriate amount of 1,2-dichloroethane as solvent. Add them together into a 100ml three-necked flask, then put in 0.24g of the synthesized target catalyst and react at 100℃ for 4h. Collect the products, and the conversion rate of cyclohexanone is measured to be 89.4%, the yield of ε-caprolactone is 86.9%, and the reaction selectivity is 97.2%.

[0052] Example 2

[0053] This embodiment adopts the same inventive concept as that of embodiment 1, and the preparation of TS-1 precursor gel is consistent with that of embodiment 1, except that:

[0054] Preparation of silicotungstic acid solution:

[0055] Take 2.4g of silicotungstic acid reagent and add it to 10.0g of deionized water, and put it into a magnetic stirrer to mix it thoroughly for 30 minutes to obtain a silicotungstic acid solution for standby use.

[0056] In-situ bonding method to prepare target catalyst:

[0057] 1) Using a microinjector, add the silicotungstic acid solution into the TS-1 precursor gel at a rate of 20 ml / h to obtain a mixed precursor sol.

[0058] 2) The precursor gel was introduced into a polytetrafluoroethylene beaker, crystallized under autogenous pressure at 170°C for 72 hours, and then taken out. After being fully washed with ethanol, it was dried in a forced air drying oven at 80°C overnight, and then calcined in a muffle furnace at 480°C for 6 hours, and the target catalyst was obtained after being taken out.

[0059] 3) The taken-out target catalyst is fully ground and sieved to 60-100 meshes to obtain a catalyst that can be used for the oxidation reaction of cyclohexanone BV to prepare ε-caprolactone.

[0060] Application Example 2

[0061] Take 4.8g cyclohexanone as raw material, 6.56g 30wt% hydrogen peroxide as oxidant, and appropriate amount of 1,2-dichloroethane as solvent. Add them together into a 100ml three-necked flask, then put in 0.24g of the synthesized target catalyst and react at 100℃ for 4h. Collect the products, and the conversion rate of cyclohexanone is measured to be 92.1%, the yield of ε-caprolactone is 89.7%, and the reaction selectivity is 97.4%.

[0062] Example 3

[0063] This embodiment adopts the same inventive concept as that of embodiment 1, and the preparation of TS-1 precursor gel is consistent with that of embodiment 1, except that:

[0064] Preparation of silicotungstic acid solution:

[0065] Take 1.2g of tungstophosphoric acid reagent and add it to 10.0g of deionized water, and put it into a magnetic stirrer to mix thoroughly for 30min to obtain a tungstophosphoric acid solution for standby use.

[0066] In-situ bonding method to prepare target catalyst:

[0067] 1) Using a microinjector, add the tungstophosphoric acid solution into the TS-1 precursor gel at a rate of 20 ml / h to obtain a mixed precursor sol.

[0068] 2) The precursor gel was introduced into a polytetrafluoroethylene beaker, crystallized under autogenous pressure at 170°C for 72 hours, and then taken out. After being fully washed with ethanol, it was dried in a forced air drying oven at 80°C overnight, and then calcined in a muffle furnace at 480°C for 6 hours, and the target catalyst was obtained after being taken out.

[0069] 3) The taken-out target catalyst is fully ground and sieved to 60-100 meshes to obtain a catalyst that can be used for the oxidation reaction of cyclohexanone BV to prepare ε-caprolactone.

[0070] Application Example 3

[0071] Take 4.8g cyclohexanone as raw material, 6.56g 30wt% hydrogen peroxide as oxidant, and appropriate amount of 1,2-dichloroethane as solvent. Add them together into a 100ml three-necked flask, then put in 0.24g of the synthesized target catalyst and react at 100℃ for 4h. Collect the products, and the conversion rate of cyclohexanone is measured to be 87.9%, the yield of ε-caprolactone is 80.6%, and the reaction selectivity is 91.7%.

[0072] Example 4

[0073] This embodiment adopts the same inventive concept as that of embodiment 1, and the preparation of TS-1 precursor gel is consistent with that of embodiment 1, except that:

[0074] Preparation of silicotungstic acid solution:

[0075] Take 2.4g of tungstophosphoric acid reagent and add it to 10.0g of deionized water, and put it into a magnetic stirrer to mix thoroughly for 30min to obtain a tungstophosphoric acid solution for standby use.

[0076] In-situ bonding method to prepare target catalyst:

[0077] 1) Using a microinjector, add the tungstophosphoric acid solution into the TS-1 precursor gel at a rate of 20 ml / h to obtain a mixed precursor sol.

[0078] 2) The precursor gel was introduced into a polytetrafluoroethylene beaker, crystallized under autogenous pressure at 170°C for 72 hours, and then taken out. After being fully washed with ethanol, it was dried in a forced air drying oven at 80°C overnight, and then calcined in a muffle furnace at 480°C for 6 hours, and the target catalyst was obtained after being taken out.

[0079] 3) The taken-out target catalyst is fully ground and sieved to 60-100 meshes to obtain a catalyst that can be used for the oxidation reaction of cyclohexanone BV to prepare ε-caprolactone.

[0080] Application Example 4

[0081] Take 4.8g cyclohexanone as raw material, 6.56g 30wt% hydrogen peroxide as oxidant, and appropriate amount of 1,2-dichloroethane as solvent. Add them together into a 100ml three-necked flask, then put in 0.24g of the synthesized target catalyst and react at 100℃ for 4h. Collect the products, and the conversion rate of cyclohexanone is 89.4%, the yield of ε-caprolactone is 83.2%, and the reaction selectivity is 93.1%.

[0082] Comparative Example 1

[0083] Take 4.8g cyclohexanone as raw material, 6.56g 30wt% hydrogen peroxide as oxidant, and appropriate amount of 1,2-dichloroethane as solvent. Add them together into a 100ml three-necked flask, then put in 0.24g pure TS-1 molecular sieve as catalyst and react at 100℃ for 4h. Collect the products, and the conversion rate of cyclohexanone is 53.9%, the yield of ε-caprolactone is 31.1%, and the reaction selectivity is 57.7%.

[0084] Comparison of catalytic performance between application examples and comparative examples

[0085]

[0086]

[0087] Through the data analysis of the above application examples and comparative examples, the target catalyst synthesized by the present invention has greatly improved the conversion rate of cyclohexanone, the yield of ε-caprolactone and the reaction selectivity compared with the pure TS-1 molecular sieve. This is because the present invention realizes the bonding of the Ti-O bond in the molecular sieve and the MO bond in the heteropoly acid (M is the central atom in the polyacid substance), strengthens the B acid site in the catalyst, and makes the B acid and L acid sites in the catalyst act synergistically in the catalytic system.

[0088] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for a person skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to replace some of the technical features therein with equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions claimed to be protected by the present invention.

Claims

1. A method for preparing a catalyst for preparing ε-caprolactone by oxidation of cyclohexanone BV, characterized in that: The steps are as follows: S1, preparing TS-1 precursor gel; S2. preparing a heteropoly acid solution: adding a certain amount of heteropoly acid into deionized water and mixing evenly to obtain a heteropoly acid solution; S3. Preparation of target catalyst by in-situ bonding method: S31, adding the heteropoly acid solution into the TS-1 precursor gel at a certain rate by using a microinjector, and obtaining a mixed precursor sol after sufficient mixing; S32, introducing the precursor gel into a polytetrafluoroethylene beaker, crystallizing it under autogenous pressure at a set temperature for a set time, then taking it out, washing it thoroughly with ethanol, drying it, and then calcining it to obtain the target catalyst; S33, grinding and sieving the obtained target catalyst to 60-100 mesh.

2. The method for preparing a catalyst for preparing ε-caprolactone by oxidation of cyclohexanone BV according to claim 1, characterized in that: The preparation of TS-1 precursor gel in step S1 specifically includes: S11, taking a certain amount of template agent and mixing it with deionized water for a period of time, using a micro-injector to drop a certain amount of silicon source into the alkali solution at a certain rate, and stirring at room temperature to fully hydrolyze it, which is recorded as solution A; S12, taking a certain amount of titanium source and mixing it with isopropanol, and then putting it into an ultrasonic cleaner and shaking it thoroughly to make it fully mixed to form a solution B; S13. Add solution B into solution A using a microinjector and stir evenly at room temperature to obtain a TS-1 precursor gel.

3. The method for preparing a catalyst for preparing ε-caprolactone by oxidation of cyclohexanone BV according to claim 2, characterized in that: Also included are: S14. The obtained TS-1 precursor gel is stirred at room temperature using a magnetic stirrer, then aged at room temperature for a certain period of time, and de-alcoholized at a certain temperature for a certain period of time, and deionized water is continuously added to maintain a constant water content in the gel.

4. The method for preparing a catalyst for preparing ε-caprolactone by oxidation of cyclohexanone BV according to claim 2 or 3, characterized in that: The template agent is one or more of tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide (TEAOH), tetrapropylammonium hydroxide (TPAOH), tetrabutylammonium hydroxide (TBAOH), tetramethylammonium bromide (TMABr), tetraethylammonium bromide (TEABr), tetrapropylammonium bromide (TPABr) and tetrabutylammonium bromide (TBABr); The silicon source is one or more of tetramethyl silicate (TMOS), tetraethyl silicate (TEOS), tetrapropyl silicate (TPOS) and tetrabutyl silicate (TBOS); The titanium source is one or more of tetraethyl titanate (TEOT), tetrabutyl titanate (TBOT), titanium tetrachloride (TiCl4), titanium tetrabromide (TiBr4) and titanium oxide (TiO2).

5. The method for preparing a catalyst for preparing ε-caprolactone by oxidation of cyclohexanone BV according to claim 4, characterized in that: The titanium source is one or more of tetraalkyl titanate, titanium tetrachloride, titanium tetrabromide and titanium oxide.

6. The method for preparing a catalyst for preparing ε-caprolactone by oxidation of cyclohexanone BV according to any one of claims 1 to 3, characterized in that: The heteropoly acid is one or more of tungstophosphoric acid, molybdophosphoric acid and silicotungstic acid.

7. The method for preparing a catalyst for preparing ε-caprolactone by oxidation of cyclohexanone BV according to claim 5, characterized in that: The template is tetrapropylammonium hydroxide, the silicon source is tetraethyl silicate, and the titanium source is tetrabutyl titanate. In S31, the molar composition of the mixed precursor sol is n(TEOS):n(TPAOH):n(TBOT):n(H2O)=1:0.10~0.20:0.10~0.20:20~100.

8. The method for preparing a catalyst for preparing ε-caprolactone by oxidation of cyclohexanone BV according to claim 7, characterized in that: In S32, the crystallization temperature is 120-170°C, the crystallization time is 24-96h, and the calcination temperature is 400-550°C.

9. A catalyst for preparing ε-caprolactone by oxidation of cyclohexanone BV, prepared by the preparation method according to any one of claims 1 to 8, characterized in that: The catalyst is used for preparing epsilon-caprolactone by oxidation of cyclohexanone BV. The method comprises the following steps: placing cyclohexanone, hydrogen peroxide, an organic solvent and the synthesized catalyst in a reactor for oxidation reaction to obtain epsilon-caprolactone.

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