Sn-beta molecular sieve, preparation method therefor and use thereof, and oxidation reaction method for cyclic ketone

Abstract

A Sn-Beta molecular sieve, a preparation method therefor and a use thereof, and an oxidation reaction method for a cyclic ketone. The silicon-to-tin molar ratio of the molecular sieve is 8-15, and the molecular sieve has a Lewis acid content of 600-900 μmol / g as measured by pyridine infrared spectroscopy at a desorption temperature of 200°C. The Sn-Beta molecular sieve has high Sn content and high Lewis acid content, and has excellent catalytic performance for Baeyer-Villiger oxidation reaction of cyclic ketones.

Description

Sn-Beta molecular sieve, preparation method and application thereof, and oxidation reaction method of cyclic ketone

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of Chinese patent application No. 202410187146.5 filed on February 20, 2024, the contents of which are incorporated herein by reference. Technical Field

[0003] The present invention relates to the field of molecular sieve synthesis, and in particular to a Sn-Beta molecular sieve, a preparation method and application thereof, and an oxidation reaction method of a cyclic ketone. Background Art

[0004] Mobil Corporation first synthesized beta zeolite in 1967, and it has been widely used since its synthesis. Due to its unique topological structure, high silicon-aluminum ratio, and strong acidity, beta zeolite exhibits excellent thermal stability, acid resistance, coking resistance, and catalytic activity in a range of catalytic reactions. As the application value of beta zeolite in the petrochemical industry continues to be understood, research on its synthesis has deepened. Introducing heteroatoms into the beta zeolite framework is one of the key approaches to improving the catalytic performance of molecular sieves. Heteroatom molecular sieves are molecular sieves containing other elements, formed by replacing part of the silicon, aluminum, or phosphorus in the molecular sieve framework with other elements. The introduced heteroatoms can be metal atoms or non-metal atoms, and after the introduction of heteroatoms, the molecular sieve can retain its original framework structure.

[0005] In recent years, Sn-Beta molecular sieves have attracted the attention of numerous researchers. These molecular sieves can be used to catalyze a variety of chemical reactions, such as the Baeyer-Villiger oxidation of cyclohexanone. The framework Sn atoms in the Sn-Beta molecular sieve possess Lewis acidity, activating the carbonyl group of cyclohexanone. H2O2 then inserts an oxygen atom into the position of the Sn-activated carbonyl group, and the intermediate undergoes structural rearrangement to form ε-caprolactone. Sn-Beta is a very promising new molecular sieve material, but due to the mismatch between the radius of the Sn atom and the radius of the Si and Al atoms in the molecular sieve, embedding Sn atoms into the framework of the Si-alumina molecular sieve is quite difficult.

[0006] In "Sn-zeolite beta as a heterogeneous chemoselective catalyst for Baeyer-Villiger oxidations," Avelino Corma et al. reported a Sn-beta molecular sieve and its synthesis method in Nature, Volume 412. Using tetraethyl orthosilicate (TEOS) as a silicon source, SnCl4·5H2O as a tin source, and HF as a mineralizer, the Sn-beta molecular sieve was obtained by high-temperature crystallization for 20 days with the aid of dealuminated nano-beta seeds. However, the synthesis of this molecular sieve required the use of fluorine ions as a mineralizer, resulting in larger crystals and a low tin content.

[0007] Xiaomei Yang et al. reported a Sn-beta molecular sieve in "Fluoride-free and low-concentration template synthesis of hierarchical Sn-Beta zeolites: efficient catalysts for conversion of glucose to alkyl lactate," Volume 19 of Green Chemistry. This method allows for the synthesis of Sn-beta molecular sieves without the use of fluoride ions and in a low-template environment. However, this Sn-beta molecular sieve has a silicon-to-tin ratio of 82-157 and a relatively small specific surface area and pore volume.

[0008] William NP et al. reported a Sn-beta molecular sieve and its synthesis method in "Synthesis of Sn-Beta with Exclusive and High Framework Sn Content," Volume 7 of ChemCatChem. The article involved acid dealumination of the beta molecular sieve, followed by dehydration and impregnation with anhydrous SnCl4. The impregnated beta molecular sieve was washed several times with methanol to remove the non-framework tin, then air-dried and calcined to obtain the Sn-beta molecular sieve. Although this molecular sieve had a high L / B acid content, it contained a low tin content and a low L acid content.

[0009] CN112678842A discloses a tin-silicon beta molecular sieve and a method for preparing the same. The Sn-beta molecular sieve is prepared by mixing a first silicon source, a tin source, a structure-directing agent, and a mineralizer in the presence of an aqueous solvent to obtain a mixture for primary crystallization. A second silicon source is dispersed in water, and a precipitant is then added dropwise to obtain a sol. The primary crystallization product is mixed with the sol, followed by secondary crystallization to obtain a product, which is then calcined to obtain the tin-silicon molecular sieve. However, this Sn-beta molecular sieve has a large particle size, a high framework silicon-tin ratio, and a low molecular sieve acid content.

[0010] CN104709920A discloses a tin heteroatom-containing functional molecular sieve and a synthesis method thereof. The Sn-beta molecular sieve is prepared by uniformly mixing a tin source, a silicon source, boric acid, a template agent, water, and a seed crystal according to a certain proportion and a feeding method, crystallizing at a certain temperature, and separating, filtering, washing, and drying after crystallization to obtain a Sn-beta molecular sieve. However, the silicon-tin ratio of the molecular sieve is within 80-1000, the molecular sieve has a relatively high silicon-tin ratio, and the skeleton tin content is low, which is not conducive to chemical reactions catalyzed by L-acids.

[0011] CN104707649A discloses a tin-containing molecular sieve with a BEA topological structure and its preparation method. The Sn-beta molecular sieve first treats the beta molecular sieve with acid, alkali or hydrothermal treatment to obtain a beta molecular sieve rich in Si-OH groups; then a tin source, an ionic liquid and the beta molecular sieve rich in Si-OH groups are mixed uniformly in a certain proportion, separated after crystallization, washed and dried to obtain the Sn-beta molecular sieve. The silicon-tin ratio of the Sn-beta molecular sieve is between 10-1000, but the skeleton Sn content of the patent is low, resulting in a low L acid content and poor catalytic oxidation performance for cyclohexanone. Summary of the Invention

[0012] To address the shortcomings of the prior art, the present invention provides a Sn-Beta molecular sieve, its preparation method and application, and a method for the oxidation of cyclic ketones. The Sn-Beta molecular sieve provided by the present invention has a high Sn content and a high L-acid content, and exhibits excellent catalytic performance in the oxidation of cyclic ketones.

[0013] A first aspect of the present invention provides a Sn-Beta molecular sieve having a silicon-tin molar ratio of 8-15 and a pyridine infrared phosphide content of 600-900 μmol / g at a desorption temperature of 200°C.

[0014] Preferably, the molecular sieve has a pyridine infrared L acid / B acid content ratio of 70-120, preferably 80-100, at a desorption temperature of 200°C.

[0015] A second aspect of the present invention provides a method for preparing Sn-Beta molecular sieve, the method comprising the following steps:

[0016] (1) Dealumination and tin supplementation reaction of HY molecular sieve with tin source to obtain Sn-Al-FAU molecular sieve;

[0017] (2) in the presence of Beta zeolite seed crystals, the Sn-Al-FAU molecular sieve is crystallized to obtain Sn-Al-Beta molecular sieve;

[0018] (3) The Sn-Al-Beta molecular sieve is dealuminated and then subjected to a tin supplementation treatment.

[0019] The method provided by the present invention first moderately dealuminates and adds tin to a Y molecular sieve using a tin source, particularly a vapor-phase tin source, to allow Sn atoms to enter the molecular sieve framework, thereby obtaining a Sn-Al-FAU molecular sieve. The Sn-Al-FAU molecular sieve is then crystallized to obtain a Sn-Al-Beta molecular sieve. Finally, the Sn-Al-Beta molecular sieve is subjected to a secondary dealumination treatment, followed by a tin source for tin addition, thereby obtaining a Sn-Beta molecular sieve with a high framework Sn content. The Sn-beta molecular sieve synthesized by this method has the advantages of uniform Sn species distribution and high framework Sn content, which is manifested by a high Lewis acid content, resulting in high reactivity and product selectivity in L-acid-catalyzed cyclic ketone oxidation reactions.

[0020] The third aspect of the present invention provides the use of the Sn-Beta molecular sieve described in the first aspect in a cyclic ketone oxidation reaction, a sugar isomerization reaction, a glucose to methyl lactate reaction, a lactic acid to L-lactide reaction, a propane dehydrogenation reaction, or a hydrogen transfer reaction between aldehydes, ketones, and alcohols, preferably in a cyclic ketone oxidation reaction, and more preferably in a cyclohexanone oxidation reaction.

[0021] The fourth aspect of the present invention provides a method for the oxidation reaction of a cyclic ketone, which comprises: reacting the cyclic ketone with an oxidant under oxidation reaction conditions in the presence of a solvent and a catalyst; the catalyst is the Sn-Beta molecular sieve described in the first aspect.

[0022] The Sn-Beta molecular sieve provided by the present invention has better activity in the oxidation reaction of cyclic ketones and high selectivity and yield for the reaction product lactone. In addition, the Sn-Beta molecular sieve prepared by the present invention is simple to operate, avoids the use of fluoride ions, and significantly reduces environmental pollution. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] FIG1 is an XRD diffraction pattern of the Sn-Beta molecular sieve prepared in Example 4;

[0024] FIG2 is a 30k magnification SEM image of the Sn-Beta molecular sieve prepared in Example 4. DETAILED DESCRIPTION

[0025] 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.

[0026] In the present invention, unless otherwise explicitly stated, percentages and contents are all based on mass.

[0027] A first aspect of the present invention provides a Sn-Beta molecular sieve having a silicon-tin molar ratio of 8-15 and a pyridine infrared phosphide content of 600-900 μmol / g at a desorption temperature of 200°C.

[0028] In the present invention, the term "Sn-Beta molecular sieve" does not specifically limit the properties and structure of the product provided by the present invention. As long as the Beta molecular sieve contains Sn element and the silicon-tin molar ratio of the molecular sieve and the pyridine infrared phosphide content at a desorption temperature of 200°C meet the requirements of the present invention, they are within the scope of protection of the present invention.

[0029] The crystal form of the molecular sieve can be determined by XRD characterization.

[0030] According to the present invention, the silicon-tin molar ratio of the molecular sieve may be 8, 9, 10, 11, 12, 13, 14 or 15. Preferably, the silicon-tin molar ratio of the molecular sieve is 10-12.

[0031] In the present invention, the silicon-tin molar ratio of the molecular sieve and the SiO2 / Al2O3 molar ratio of the molecular sieve are measured by inductively coupled plasma atomic emission spectroscopy (ICP-AES). Before the test, the molecular sieve solid powder is pretreated and added to a mixed solution of water, nitric acid, and hydrofluoric acid. The powder is heated at 150°C until the sample is completely dissolved and becomes a transparent solution. After cooling, the solution is transferred to a volumetric flask, fixed to volume with deionized water, and shaken. Quantitative analysis is then performed using a standard curve method. Finally, the measured element contents are converted into the form of silicon-aluminum molar ratio (SiO2 / Al2O3) and silicon-tin molar ratio (SiO2 / SnO2).

[0032] According to the present invention, preferably, the molecular sieve has a pyridine infrared L-acid content of 700-800 μmol / g at a desorption temperature of 200°C, for example, 700 μmol / g, 710 μmol / g, 720 μmol / g, 730 μmol / g, 740 μmol / g, 750 μmol / g, 760 μmol / g, 770 μmol / g, 780 μmol / g, 790 μmol / g, 800 μmol / g. The molecular sieve provided by the present invention has a higher pyridine infrared L-acid content at a desorption temperature of 200°C.

[0033] According to the present invention, preferably, the molecular sieve has a pyridine infrared L-acid / B-acid content ratio of 70-120 at a desorption temperature of 200° C., for example, 70, 80, 90, 100, 110, or 120, preferably 80-100. Using a molecular sieve with an appropriate L-acid / B-acid content ratio is more conducive to improving the conversion rate and selectivity of the molecular sieve during the reaction process.

[0034] In the present invention, the contents of L acid (mainly generated by the framework Sn atoms) and B acid (mainly generated by the Al atoms) of the molecular sieve are measured by pyridine-infrared spectroscopy. Specifically, the sample is prepared into a self-supporting sheet, heated to 500°C and maintained for 2 hours, and then vacuumed. The sample is allowed to cool naturally and then adsorbed with pyridine for 30 minutes at room temperature. The temperature is then raised to 200°C and vacuumed to remove the adsorbed pyridine molecules. The pyridine infrared spectrum at this temperature is recorded. The infrared spectrum of pyridine at 1450 cm -1 The peak at 1545 cm is attributed to the L-acid absorption peak produced by Sn atoms. -1 The peak at is attributed to the absorption peak of Br(Ⅱ) acid produced by Al atoms. After integrating the peak area of ​​the spectrum, the infrared L(Ⅱ) acid and Br(Ⅱ) acid contents are obtained. The quantitative calculation of L(Ⅱ) acid can be obtained by the following formula:

[0035] I A 1450cm in the spectrum -1 The integrated area of ​​the absorption peak at ; a and m are the area and mass of the self-supporting sample, respectively; E is the integrated molar extinction coefficient, E = 1.42 cm / μmol.

[0036] The quantitative calculation of B acid can be obtained by the following formula:

[0037] I A 1545cm in the spectrum -1 The integrated area of ​​the absorption peak at ; a and m are the area and mass of the self-supporting sample, respectively; E is the integrated molar extinction coefficient, E = 1.95 cm / μmol.

[0038] According to the present invention, preferably, the SiO2 / Al2O3 molar ratio of the molecular sieve is 2700-4000, for example, 2700, 2800, 2900, 3000, 3100, 3200, 3300, 3400, 3500, 3600, 3700, 3800, 3900 or 4000, preferably 3000-3500.

[0039] According to the present invention, preferably, the molecular sieve has a nanometer-scale crystal size, and further preferably, the average crystal size of the molecular sieve is 30-100 nm, preferably 50-70 nm. The molecular sieve provided by the present invention has a smaller crystal size and better catalytic oxidation performance.

[0040] In the present invention, the grain size refers to the maximum straight-line distance between any two different points on the grain. For example, when the grain is spherical, the size refers to its diameter.

[0041] The crystal size of the molecular sieve of the present invention can be measured by scanning electron microscopy (SEM). When SEM measurement is adopted, 30 SEM photos of the sample at different positions are selected, and the crystal size of the crystals is measured and the average result is taken to obtain the average particle size of the crystals.

[0042] According to the present invention, preferably, the specific surface area of ​​the molecular sieve is 530-630m 2 / g, preferably 550-600m 2 / g.

[0043] According to the present invention, preferably, the external specific surface area of ​​the molecular sieve is 130-180m 2 / g, preferably 145-165m 2 / g.

[0044] According to the present invention, preferably, the pore volume of the molecular sieve is 0.32-0.43 mL / g, preferably 0.36-0.4 mL / g.

[0045] The molecular sieve provided by the present invention has a large specific surface area, external specific surface area and large pore volume. In the present invention, the specific surface area, external specific surface area and pore volume of the molecular sieve are measured by N2-adsorption desorption method. Before measurement, the sample is first pretreated at 300 ° C for 3 hours, and then tested by nitrogen adsorption at 77K. The specific surface area of ​​the molecular sieve is calculated by the BET method, and the pore volume is calculated at p / p 0 =0.98, and the external specific surface area was obtained by t-Plot method.

[0046] The molecular sieves having the aforementioned properties of the present invention can achieve the purpose of the present invention, and there is no special requirement for their preparation methods. According to a preferred embodiment of the present invention, the second aspect of the present invention provides a method for preparing Sn-Beta molecular sieve, the method comprising the following steps:

[0047] (1) Dealumination and tin supplementation reaction of HY molecular sieve with tin source to obtain Sn-Al-FAU molecular sieve;

[0048] (2) in the presence of Beta zeolite seed crystals, the Sn-Al-FAU molecular sieve is crystallized to obtain Sn-Al-Beta molecular sieve;

[0049] (3) The Sn-Al-Beta molecular sieve is dealuminated and then subjected to a tin supplementation treatment.

[0050] In the present invention, the HY molecular sieve raw material can be any commercially available product or any HY molecular sieve prepared according to the prior art. Preferably, the HY molecular sieve in step (1) is obtained by ammonium exchange with NaY molecular sieve followed by calcination.

[0051] Preferably, in step (1), the mass content of Na2O in the HY molecular sieve is 0.5-1.5%, preferably 0.8-1.2%.

[0052] According to the method provided by the present invention, the Na2O content in the molecular sieve is measured by X-ray fluorescence (XRF).

[0053] According to the method provided by the present invention, preferably, in step (1), the SiO2 / Al2O3 molar ratio of the HY molecular sieve is 3.8-5, preferably 4.2-4.6.

[0054] The specific method for dealumination and tin supplementation in step (1) of the present invention can be selected from a wide range, as long as the purpose of dealumination and tin supplementation can be achieved. Specifically, the operation method of dealumination and tin supplementation includes: contacting the HY molecular sieve with a dealumination and tin supplementation agent (tin source) under dealumination and tin supplementation reaction conditions. According to a preferred embodiment of the present invention, the tin source is provided in a vapor phase.

[0055] According to the present invention, preferably, the dealumination and tin supplementation reaction in step (1) comprises reacting the HY molecular sieve with a gaseous tin source under dealumination and tin supplementation reaction conditions. This preferred embodiment not only facilitates the preparation of a product with further improved performance, but also facilitates better separation of the molecular sieve and the tin source reactant after the reaction.

[0056] According to the present invention, preferably, the dealumination and tin supplementation reaction conditions include: a reaction temperature of 400-600°C, preferably 450-550°C, a reaction time of 0.5-5 hours, preferably 2-3 hours; and a partial pressure of the gaseous tin source of 2.5kPa-7.5kPa, preferably 4kPa-6kPa. According to the present invention, preferably, the tin source is an anhydrous tin source, and more preferably, the tin source is at least one of tin tetrachloride, trichloromethyltin, dimethyltin dichloride, and trimethyltin chloride.

[0057] According to the present invention, preferably, no solvent (such as water) is present during the dealumination and tin supplementation reaction.

[0058] According to one embodiment of the present invention, the dealumination and tin supplementation reaction is carried out under an inert gas flow. Preferably, the inert gas flow carries the gaseous tin source into the reactor to react with the HY molecular sieve. The inert gas is a conventional inert gas in the art, preferably selected from nitrogen, helium, argon, or a mixture thereof in any proportion.

[0059] According to the present invention, the dealumination and tinning reaction in step (1) can be carried out under normal pressure. There are no particular limitations on the specific operating method, and conventional selection and appropriate adjustments can be made based on the above disclosure. For example, during the dealumination and tinning reaction, the pressure of the mixed gas at the inlet is slightly higher than the pressure at the outlet to maintain the mixed gas flowing in a forward direction at a certain flow rate.

[0060] According to the present invention, preferably, the flow rate of the mixed gas of the tin source and the inert gas in the dealumination and tin supplementation reaction conditions in step (1) is 5-20 mL / (min·g).

[0061] According to the present invention, there is no particular limitation on the specific manner of carrying out the dealumination and tin supplementation reaction in step (1), which can be carried out in a fixed bed reactor.

[0062] According to the present invention, preferably, the method further comprises dehydrating the HY molecular sieve before the dealumination and tin supplementation reaction. This is more conducive to ensuring that step (1) is carried out under anhydrous conditions. Preferably, the specific method of dehydrating the HY molecular sieve includes: dehydrating the molecular sieve under an inert atmosphere.

[0063] Preferably, the dehydration conditions include: a dehydration temperature of 350-550° C., preferably 400-470° C., and a dehydration time of 2-10 h, preferably 4-7 h.

[0064] Preferably, the method further comprises, after the dealumination and tin supplementation reaction in step (1), stopping the introduction of the tin source, introducing an inert gas for purging, and then cooling, preferably cooling to room temperature before performing step (2).

[0065] According to a preferred embodiment of the present invention, step (2) comprises: mixing Beta zeolite seed crystals, a template, a silicon source, a Sn-Al-FAU molecular sieve and a solvent to obtain a mixed solution, then performing a crystallization reaction, and calcining the crystallized solid product.

[0066] Preferably, the molar ratio of materials in the mixed solution is SiO2: (0.03-0.09) Al2O3: (0.03-0.08) SnO2: (0.006-0.021) Na2O: (0.1-0.8) template: (3-8) H2O, preferably SiO2: (0.05-0.07) Al2O3: (0.05-0.07) SnO2: (0.009-0.018) Na2O: (0.4-0.6) template: (5-7) H2O.

[0067] Preferably, the Beta zeolite seed crystals account for 3-10 wt %, preferably 6-8 wt %, of the total amount of silica in the mixed solution, calculated as silica.

[0068] The present invention has a wide range of selection for the types of the Beta zeolite seed crystal, template agent, silicon source and solvent.

[0069] The Beta zeolite seed crystals may be prepared by any method in the art. Preferably, the SiO2 / Al2O3 molar ratio of the Beta zeolite seed crystals is 20-35, more preferably 25-30.

[0070] The template can be any template capable of transforming Sn-Al-FAU into Sn-Al-Beta molecular sieve. Preferably, the template is tetraethylammonium hydroxide. Specifically, the template can be provided in the form of an aqueous solution. Preferably, the concentration of the template aqueous solution is 20-40 wt%.

[0071] The silicon source can be any silicon source commonly used in the synthesis of molecular sieves in the art. Preferably, the silicon source is at least one of white carbon black, fumed silica, and silica sol.

[0072] The solvent includes but is not limited to water.

[0073] According to a preferred embodiment of the present invention, in step (2), the crystallization conditions include: a crystallization temperature of 138-145° C., preferably 140-142° C.; and a crystallization time of 5-15 days, preferably 8-12 days. The crystallization can be carried out in a reactor.

[0074] According to a preferred embodiment of the present invention, the crystallization is carried out under closed conditions.

[0075] According to a preferred embodiment of the present invention, in step (2), the calcination conditions include: a calcination temperature of 500-600° C., and a calcination time of 4-8 hours.

[0076] Preferably, the method further comprises filtering, washing, and drying the crystallized product before the calcination in step (2). The present invention does not particularly limit the conditions for filtering, washing, and drying, and those skilled in the art can select them according to conventional technical means.

[0077] According to the present invention, preferably, the dealumination in step (3) includes subjecting the Sn-Al-Beta molecular sieve to acid treatment. There is no particular limitation on the specific conditions and operation mode of the acid treatment.

[0078] According to the present invention, preferably, the dealumination in step (3) comprises: reacting the Sn-Al-Beta molecular sieve with an acid solution.

[0079] The acid used in the dealumination step (3) of the present invention has a wide range of options and can be an inorganic acid and / or an organic acid, preferably an inorganic acid. The inorganic acid is preferably at least one of nitric acid, hydrochloric acid, and sulfuric acid. The organic acid is preferably at least one of citric acid, oxalic acid, EDTA, and tartaric acid.

[0080] According to the present invention, preferably, the concentration of the acid solution is 2.5-5 mol / L, preferably 3.5-4.5 mol / L.

[0081] According to the present invention, preferably, the solid-liquid mass ratio of the Sn-Al-Beta molecular sieve to the acid solution is 1:30-1:100, preferably 1:50-1:70.

[0082] According to the present invention, preferably, the conditions for reacting the Sn-Al-Beta molecular sieve with the acid solution include: a temperature of 30-90°C, preferably 50-70°C, and a time of 1-6 hours, preferably 3-4 hours. The present invention does not particularly limit the number of acid treatments, which can be 1 or 2 or more, and preferably 2-5, preferably 3-4 times.

[0083] Preferably, the method further comprises washing, filtering, and drying the solid product obtained after the dealumination in step (3). The present invention does not particularly limit the conditions for washing, filtering, and drying, and those skilled in the art can select them according to conventional techniques. The drying conditions preferably include: a temperature of 120-160° C. and a drying time of 4-6 hours.

[0084] According to the present invention, preferably, the tin supplementation treatment in step (3) comprises: reacting the dealuminated molecular sieve with a gaseous tin source under tin supplementation treatment conditions. In the present invention, the specific operation method of the tin supplementation in step (3) can be the same as that in step (1), and the present invention will not be repeated here.

[0085] According to a preferred embodiment of the present invention, in step (3), the tin source is provided in a gaseous form. According to a specific embodiment of the present invention, the tin supplementation reaction is carried out under an inert gas flow. The tin source is carried into the reactor by the inert gas flow to react with the molecular sieve obtained by dealumination.

[0086] According to the present invention, preferably, the conditions of the tin supplementation treatment include: reaction temperature of 400-550°C, preferably 450-500°C, time of 2-7h, preferably 4-6h; partial pressure of the tin source in the gas phase is 1kPa-4kPa, preferably 2kPa-3kPa.

[0087] According to the present invention, specifically, the tin supplementation treatment stage is carried out under normal pressure, and the pressure of the gas inlet is slightly higher than the pressure of the outlet to maintain the mixed gas flowing forward at a certain flow rate.

[0088] According to the present invention, preferably, the flow rate of the mixed gas of the tin source and the inert gas in the tin supplementation treatment reaction conditions in step (3) is 5-20 mL / (min·g).

[0089] The type of tin source used in the tin supplementation process can be the same as the selection range of the above step (1), and the present invention will not be repeated here.

[0090] According to the present invention, preferably, the method further comprises dehydrating the dealuminated Sn-Beta molecular sieve before the tin supplementation treatment. This is more conducive to ensuring that step (3) is performed under anhydrous conditions. Preferably, the specific method of dehydrating the dealuminated Sn-Beta molecular sieve comprises: dehydrating the dealuminated Sn-Beta molecular sieve under an inert atmosphere.

[0091] The Sn-Beta molecular sieve described in the first aspect of the present invention has a wide range of application fields, and can be applied to various technical fields where existing Sn-Beta molecular sieves can be applied, including but not limited to: cyclic ketone oxidation reaction, sugar isomerization reaction, glucose to methyl lactate reaction, lactic acid to L-lactide reaction, propane dehydrogenation reaction, and hydrogen transfer reaction between aldehydes, ketones and alcohols.

[0092] The third aspect of the present invention provides the use of the Sn-Beta molecular sieve described in the first aspect above in a cyclic ketone oxidation reaction, a saccharide isomerization reaction, a glucose to methyl lactate reaction, a lactic acid to L-lactide reaction, a propane dehydrogenation reaction, or a hydrogen transfer reaction between aldehydes, ketones, and alcohols, preferably in a cyclic ketone oxidation reaction. The inventors of the present invention have found that the Sn-Beta molecular sieve is particularly suitable for cyclic ketone oxidation reactions. The Sn-Beta molecular sieve provided by the present invention has high performance in the oxidation reaction of cyclic ketones, especially the Baeyer-Villiger oxidation reaction. The Sn-Beta molecular sieve of the present invention is suitable for the oxidation reaction of a variety of cyclic ketones, such as at least one of cyclohexanone, 2-adamantanone, dihydrocarvone, and bicyclo[3.2.0]hept-2-en-6-one, preferably the use of the Sn-Beta molecular sieve in the oxidation reaction of cyclohexanone.

[0093] The fourth aspect of the present invention provides a method for the oxidation reaction of a cyclic ketone, which comprises: reacting the cyclic ketone with an oxidant under oxidation reaction conditions in the presence of a solvent and a catalyst; the catalyst is the Sn-Beta molecular sieve described in the first aspect.

[0094] Preferably, the cyclic ketone is at least one of cyclohexanone, 2-adamantanone, dihydrocarvone and bicyclo[3,2,0]hept-2-en-6-one, more preferably cyclohexanone.

[0095] The present invention has a wide range of choices for the oxidant, and any conventional choice in the art can be used as long as it can oxidize the cyclic ketone. Preferably, the oxidant is selected from at least one of tert-butyl hydroperoxide, hydrogen peroxide, cumene hydroperoxide, cyclohexyl hydroperoxide, peracetic acid, and peroxypropionic acid, preferably hydrogen peroxide.

[0096] The present invention has a wide range of choices for the type of solvent, as long as it can provide a reaction environment. Preferably, the solvent is selected from at least one of 1,4-dioxane, decane, chlorobenzene and benzyl alcohol.

[0097] Preferably, the amount of the cyclic ketone used is 0.4-1.4 mmol relative to 1 mmol of the oxidizing agent.

[0098] Preferably, the amount of the catalyst used is 10-25 mg relative to 1 mmol of the oxidant.

[0099] Preferably, the oxidation reaction conditions include: oxidation reaction temperature of 75-95° C., and oxidation reaction time of 2-8 h.

[0100] It should be noted that, in the present invention, unless otherwise explicitly stated, percentages and contents are all based on mass.

[0101] The preparation process and product performance of the method of the present invention are further illustrated below in conjunction with examples and comparative examples, but the following examples do not constitute a limitation of the method of the present invention.

[0102] In the following examples and comparative examples, the molecular sieve silicon-tin molar ratio and the SiO2 / Al2O3 molar ratio were determined by inductively coupled plasma atomic emission spectroscopy (ICP-AES). The L-acid and B-acid contents of the molecular sieves were measured using pyridine-infrared spectroscopy. The specific surface area, external specific surface area, and pore volume of the molecular sieves were measured using N2 adsorption-desorption.

[0103] The average crystallite size of the molecular sieve can be measured by scanning electron microscopy (SEM).

[0104] The Na2O content in the molecular sieve was measured by X-ray fluorescence (XRF).

[0105] The specific conditions of each test method are as described in the above specific implementation method section and will not be repeated here.

[0106] The silicon-to-aluminum ratio described in the following examples and comparative examples refers to the molar ratio of SiO2 / Al2O3.

[0107] Example 1

[0108] HY molecular sieve with a silicon-aluminum ratio of 4.0 and a Na2O content of 0.6% was loaded into a fixed-bed reactor, a nitrogen flow was introduced, and the temperature was raised to 350°C for dehydration for 3 hours. Subsequently, SnCl4 vapor with a partial pressure of 7.3 kPa was carried into the reactor by the nitrogen flow, and the temperature was raised to 400°C. The flow rate of the mixed gas was controlled to be 12 mL / (min·g), and the reaction was carried out at this temperature for 5 hours. After the reaction, the introduction of SnCl4 was stopped, and nitrogen purging was continued at the reaction temperature for 1 hour. Subsequently, the temperature was cooled to 30°C under nitrogen purging and taken out to obtain Sn-Al-FAU molecular sieve.

[0109] A 40 wt% tetraethylammonium hydroxide solution was added to a certain amount of water and stirred uniformly. White carbon black was then added and stirred uniformly. Beta zeolite seeds (having a Si / Al ratio of 20) were then added. Finally, Sn-Al-FAU molecular sieve was added. After stirring uniformly, the solution had a molar ratio of SiO2:0.09Al2O3:0.08SnO2:0.007Na2O:0.8TEAOH:8H2O, with the Beta zeolite seeds accounting for 10 wt% of the total silica in the mixture, calculated as silica. The mixture was placed in a reactor and crystallized at 144°C for 6 days under closed conditions. After crystallization, the mixture was removed, filtered, washed, dried, and calcined at 550°C for 6 hours to obtain the Sn-Al-Beta molecular sieve product.

[0110] The obtained Sn-Al-Beta molecular sieve was placed in a 2.5 mol / L nitric acid solution for dealumination, with the solid-liquid mass ratio controlled at 1:30, and treated at 30°C for 1 hour, for a total of 2 treatments.

[0111] The dealuminated Sn-Beta molecular sieve was loaded into a fixed bed reactor, nitrogen was introduced, and the temperature was raised to 300°C for dehydration for 8 hours. Anhydrous SnCl4 was heated, and then a nitrogen flow was used to carry SnCl4 saturated vapor with a partial pressure of 4.0 kPa into the reaction tube. The temperature was raised to 550°C for reaction for 7 hours. The flow rate of the mixed gas was controlled to be 12 mL / (min·g). After the reaction, the introduction of SnCl4 was stopped, and nitrogen purging was continued at the reaction temperature for 1 hour. Then, the temperature was cooled to 30°C under nitrogen purging and taken out to obtain a secondary tin-supplemented Sn-Beta molecular sieve.

[0112] Example 2

[0113] HY molecular sieve with a silicon-aluminum ratio of 5.0 and a Na2O content of 1.4% was loaded into a fixed bed reactor, a nitrogen flow was introduced, and the temperature was raised to 520°C for dehydration for 5 hours. Subsequently, SnCl4 vapor with a partial pressure of 2.6 kPa was carried into the reactor by the nitrogen flow, and the temperature was raised to 400°C. The flow rate of the mixed gas was controlled to 12 mL / (min·g), and the reaction was carried out at this temperature for 0.5 hours. After the reaction, the introduction of SnCl4 was stopped, and nitrogen purging was continued at the reaction temperature for 1 hour. Subsequently, the temperature was cooled to 30°C under nitrogen purging and taken out to obtain Sn-Al-FAU molecular sieve.

[0114] A 40 wt% tetraethylammonium hydroxide solution was added to a certain amount of water and stirred uniformly. White carbon black was then added and stirred uniformly. Beta zeolite seeds (having a Si / Al ratio of 34) were then added. Finally, Sn-Al-FAU molecular sieve was added. After stirring uniformly, the solution had a molar ratio of SiO2:0.035Al2O3:0.03SnO2:0.020Na2O:0.2TEAOH:3H2O, with the Beta zeolite seeds accounting for 3 wt% of the total silica in the mixture, calculated as silica. The mixture was placed in a reactor and crystallized at 138°C for 15 days under closed conditions. After crystallization, the mixture was removed, filtered, washed, dried, and calcined at 550°C for 6 hours to obtain the Sn-Al-Beta molecular sieve product.

[0115] The obtained Sn-Al-Beta molecular sieve was placed in a nitric acid solution with a concentration of 5 mol / L for dealumination, with the solid-liquid mass ratio controlled at 1:100, and treated at 80°C for 2 h, for a total of 5 times.

[0116] The dealuminated Sn-Beta molecular sieve was loaded into a fixed-bed reactor, nitrogen was introduced, and the temperature was raised to 500°C for dehydration for 3 hours. Anhydrous SnCl4 was heated, and then a nitrogen flow was used to carry SnCl4 saturated vapor with a partial pressure of 1.2 kPa into the reaction tube. The temperature was raised to 420°C for reaction for 2 hours. The flow rate of the mixed gas was controlled to be 12 mL / (min·g). After the reaction, the introduction of SnCl4 was stopped, and nitrogen purging was continued at the reaction temperature for 1 hour. The reactor was then cooled to 30°C under nitrogen purging and taken out to obtain a secondary tin-supplemented Sn-Beta molecular sieve.

[0117] Example 3

[0118] HY molecular sieve with a silicon-aluminum ratio of 4.1 and a Na2O content of 1.3% was loaded into a fixed-bed reactor, a nitrogen flow was introduced, and the temperature was raised to 380°C for dehydration for 3 hours. Subsequently, SnCl4 vapor with a partial pressure of 6.4 kPa was carried into the reactor by the nitrogen flow, and the temperature was raised to 440°C. The flow rate of the mixed gas was controlled to be 12 mL / (min·g), and the reaction was carried out at this temperature for 4 hours. After the reaction, the introduction of SnCl4 was stopped, and nitrogen purging was continued at the reaction temperature for 1 hour. Subsequently, the temperature was cooled to 30°C under nitrogen purging and taken out to obtain Sn-Al-FAU molecular sieve.

[0119] A 40 wt% tetraethylammonium hydroxide solution was added to a certain amount of water and stirred uniformly. White carbon black was then added and stirred uniformly. Beta zeolite seeds (having a Si / Al ratio of 32) were then added. Finally, Sn-Al-FAU molecular sieve was added. After stirring uniformly, the solution had a molar ratio of SiO2:0.085Al2O3:0.045SnO2:0.019Na2O:0.3TEAOH:4H2O, with the Beta zeolite seeds accounting for 9 wt% of the total silica in the mixture, calculated as silica. The mixture was placed in a reactor and crystallized at 139°C for 7 days under closed conditions. After crystallization, the mixture was removed, filtered, washed, dried, and calcined at 550°C for 6 hours to obtain the Sn-Al-Beta molecular sieve product.

[0120] The obtained Sn-Al-Beta molecular sieve was placed in a 3 mol / L nitric acid solution for dealumination, with the solid-liquid mass ratio controlled at 1:80, and treated at 45°C for 6 hours, for a total of 2 treatments.

[0121] The dealuminated Sn-Beta molecular sieve was loaded into a fixed bed reactor, nitrogen was introduced, and the temperature was raised to 450°C for dehydration for 7 hours. Anhydrous SnCl4 was heated, and then a nitrogen flow was used to carry SnCl4 saturated vapor with a partial pressure of 3.5 kPa into the reaction tube. The temperature was raised to 430°C for reaction for 7 hours. The flow rate of the mixed gas was controlled to be 12 mL / (min·g). After the reaction, the introduction of SnCl4 was stopped, and nitrogen purging was continued at the reaction temperature for 1 hour. The reactor was then cooled to 30°C under nitrogen purging and taken out to obtain a secondary tin-supplemented Sn-Beta molecular sieve.

[0122] Example 4

[0123] HY molecular sieve with a silicon-aluminum ratio of 4.5 and a Na2O content of 1.0% was loaded into a fixed bed reactor, a nitrogen flow was introduced, and the temperature was raised to 450°C for dehydration for 6 hours. Subsequently, SnCl4 vapor with a partial pressure of 5.0 kPa was carried into the reactor by the nitrogen flow, and the temperature was raised to 500°C. The flow rate of the mixed gas was controlled to 12 mL / (min·g), and the reaction was carried out at this temperature for 2 hours. After the reaction, the introduction of SnCl4 was stopped, and nitrogen purging was continued at the reaction temperature for 1 hour. Subsequently, the temperature was cooled to 30°C under nitrogen purging and taken out to obtain Sn-Al-FAU molecular sieve.

[0124] A 40 wt% tetraethylammonium hydroxide solution was added to a certain amount of water and stirred uniformly. White carbon black was then added and stirred uniformly. Beta zeolite seeds (having a Si / Al ratio of 28) were then added. Finally, Sn-Al-FAU molecular sieve was added. After stirring uniformly, the solution had a molar ratio of SiO2:0.06Al2O3:0.05SnO2:0.014Na2O:0.5TEAOH:5H2O, with the Beta zeolite seeds accounting for 8 wt% of the total silica in the mixture, calculated as silica. The mixture was placed in a reactor and crystallized at 140°C for 10 days under closed conditions. After crystallization, the mixture was removed, filtered, washed, dried, and calcined at 550°C for 6 hours to obtain the Sn-Al-Beta molecular sieve product.

[0125] The obtained Sn-Al-Beta molecular sieve was placed in a 3.5 mol / L nitric acid solution for dealumination, with the solid-liquid mass ratio controlled at 1:70, and treated at 60°C for 4 hours, for a total of 3 treatments.

[0126] The dealuminated Sn-Beta molecular sieve was loaded into a fixed-bed reactor, nitrogen was introduced, and the temperature was raised to 400°C for dehydration for 5 hours. Anhydrous SnCl4 was heated, and then a nitrogen flow was used to carry SnCl4 saturated vapor with a partial pressure of 3.0 kPa into the reaction tube. The temperature was raised to 480°C for reaction for 5 hours, and the flow rate of the mixed gas was controlled to be 12 mL / (min·g). After the reaction, the introduction of SnCl4 was stopped, and nitrogen purging was continued at the reaction temperature for 1 hour. Then, the temperature was cooled to 30°C under nitrogen purging and the reactor was taken out to obtain a secondary tin-supplemented Sn-Beta molecular sieve.

[0127] Figure 1 is the XRD diffraction pattern of the Sn-Beta molecular sieve prepared in Example 4. It can be seen from the figure that the molecular sieve exhibits the characteristic diffraction peaks of Beta molecular sieve, and there is no diffraction peak of SnO2, indicating that most of the Sn has entered the molecular sieve framework.

[0128] FIG2 is a 50k magnification SEM image of the Sn-Beta molecular sieve prepared in Example 4. It can be seen from the figure that the grain size of the molecular sieve is nanometer-scale.

[0129] Example 5

[0130] HY molecular sieve with a silicon-aluminum ratio of 4.4 and a Na2O content of 0.8% was loaded into a fixed bed reactor, a nitrogen flow was introduced, and the temperature was raised to 410°C for dehydration for 4 hours. Subsequently, SnCl4 vapor with a partial pressure of 6.0 kPa was carried into the reactor by the nitrogen flow, and the temperature was raised to 550°C. The flow rate of the mixed gas was controlled to be 12 mL / (min·g), and the reaction was carried out at this temperature for 3 hours. After the reaction, the introduction of SnCl4 was stopped, and nitrogen purging was continued at the reaction temperature for 1 hour. Subsequently, the temperature was cooled to 30°C under nitrogen purging and taken out to obtain Sn-Al-FAU molecular sieve.

[0131] A 40 wt% tetraethylammonium hydroxide solution was added to a certain amount of water and stirred uniformly. White carbon black was then added and stirred uniformly. Beta zeolite seeds (having a Si / Al ratio of 26) were then added. Finally, Sn-Al-FAU molecular sieve was added. After stirring uniformly, the solution had a molar ratio of SiO2:0.06Al2O3:0.06SnO2:0.010Na2O:0.6TEAOH:7H2O, with the Beta zeolite seeds accounting for 6 wt% of the total silica in the mixture, calculated as silica. The mixture was placed in a reactor and crystallized at 140°C for 10 days under closed conditions. After crystallization, the mixture was removed, filtered, washed, dried, and calcined at 550°C for 6 hours to obtain the Sn-Al-Beta molecular sieve product.

[0132] The obtained Sn-Al-Beta molecular sieve was placed in a nitric acid solution with a concentration of 4.5 mol / L for dealumination, with the solid-liquid mass ratio controlled at 1:50, and treated at 50°C for 3 h, for a total of 4 times.

[0133] The dealuminated Sn-Beta molecular sieve was loaded into a fixed bed reactor, nitrogen was introduced, and the temperature was raised to 350°C for dehydration for 5 hours. Anhydrous SnCl4 was heated, and then a nitrogen flow was used to carry SnCl4 saturated vapor with a partial pressure of 2.4 kPa into the reaction tube. The temperature was raised to 460°C for reaction for 5 hours, and the flow rate of the mixed gas was controlled to be 12 mL / (min·g). After the reaction, the introduction of SnCl4 was stopped, and nitrogen purging was continued at the reaction temperature for 1 hour. Then, the temperature was cooled to 30°C under nitrogen purging and taken out to obtain a secondary tin-supplemented Sn-Beta molecular sieve.

[0134] Comparative Example 1

[0135] A 40 wt% tetraethylammonium hydroxide solution was added to a certain amount of water and stirred uniformly. Silica was then added and stirred uniformly. Beta zeolite seeds (with a Si / Al ratio of 20) were then added. HY molecular sieves with a Si / Al ratio of 4.0 and a Na2O content of 0.6% were then added. Finally, a certain amount of SnCl4·5H2O was added. After stirring uniformly, the resulting mixture had a molar ratio of SiO2:0.09Al2O3:0.08SnO2:0.007Na2O:0.8TEAOH:8H2O, with the Beta zeolite seeds accounting for 10 wt% of the total SiO in the mixture, calculated as SiO2. The mixture was placed in a reactor and crystallized at 144°C for 6 days under closed conditions. After crystallization, the mixture was removed, filtered, washed, dried, and calcined at 550°C for 6 hours to obtain a Sn-Al-Beta molecular sieve product.

[0136] The obtained Sn-Al-Beta molecular sieve was placed in a 2.5 mol / L nitric acid solution for dealumination, with the solid-liquid mass ratio controlled at 1:30, and treated at 30°C for 1 hour, for a total of 2 treatments.

[0137] The dealuminated Sn-Beta molecular sieve was loaded into a fixed bed reactor, nitrogen was introduced, and the temperature was raised to 300°C for dehydration for 8 hours. Anhydrous SnCl4 was heated, and then a nitrogen flow was used to carry SnCl4 saturated vapor with a partial pressure of 4.0 kPa into the reaction tube. The temperature was raised to 550°C for reaction for 7 hours. The flow rate of the mixed gas was controlled to be 12 mL / (min·g). After the reaction, the introduction of SnCl4 was stopped, and nitrogen purging was continued at the reaction temperature for 1 hour. Then, the temperature was cooled to 30°C under nitrogen purging and taken out to obtain a secondary tin-supplemented Sn-Beta molecular sieve.

[0138] Comparative Example 2

[0139] 3 g of Beta molecular sieve (silicon to aluminum molar ratio = 21) was treated with concentrated nitric acid (concentration 65%) at a liquid:solid ratio of 20 (weight ratio) at 100°C for 24 hours to obtain Si-OH-rich Beta molecular sieve (silicon to aluminum ratio > 2000).

[0140] Then, in a reactor, 100 g of the dissolved 1-butyl-3-methylchloroimidazolium salt ionic liquid was weighed, 1.5 g of tin tetrachloride was added, and the mixture was vigorously stirred and reacted for 4 hours. Then, the Si-OH-rich Beta molecular sieve obtained above was added, and the mixture was vigorously stirred and reacted for 4 hours to obtain a uniformly mixed crystallized mixture with a molar ratio of 1.0SiO2:0.1SnO2.

[0141] The prepared crystallization mixture was mixed uniformly and then transferred to an open reactor for crystallization at 200° C. for 20 hours. After the crystallization, the reactant was cooled to room temperature, filtered, washed, and dried to obtain a tin-containing Beta heteroatom molecular sieve.

[0142] The structural properties of the molecular sieves prepared in the above examples and comparative examples are listed in Tables 1 and 2 below.

[0143] Table 1

[0144] Table 2

[0145] Test Case

[0146] This test example is used to illustrate the performance of the molecular sieve provided by the present invention in the Baeyer-Villiger oxidation reaction.

[0147] The performance of the Sn-Beta molecular sieves in the examples and comparative examples was evaluated using the Baeyer-Villiger oxidation reaction of cyclohexanone and hydrogen peroxide (35 wt%). The reaction was carried out in a round-bottom flask with a condenser water cooler. 50 mg of the catalyst was weighed and added to the flask. Then, 10 mL of 1,4-dioxane (solvent), 2 mmol of cyclohexanone, 3 mmol of H2O2 (35 wt%), and 0.23 g of chlorobenzene (internal standard) were added. The reaction solution was placed in a 90°C oil bath for 3 h. After the reaction, the solution was transferred to ice water and cooled to room temperature. After centrifugation, the supernatant was analyzed by gas chromatography for cyclohexanone conversion, selectivity for the target product ε-caprolactone, and yield. The evaluation results are shown in Table 3.

[0148] Table 3

[0149] Combining the product properties in Tables 1 and 2 and the evaluation results in Table 3, it can be seen that the Sn-beta molecular sieve prepared in the present invention has a high Sn content, a high L acid content, and a high L / B acid ratio. These properties enable the molecular sieve to exhibit better activity and selectivity in the Baeyer-Villiger oxidation reaction of cyclic ketones.

Claims

1. A Sn-Beta molecular sieve, characterized in that The silicon-tin molar ratio of the molecular sieve is 8-15, and the pyridine infrared phosphide content of the molecular sieve is 600-900 μmol / g at a desorption temperature of 200° C.

2. The molecular sieve according to claim 1, wherein The silicon-tin molar ratio of the molecular sieve is 10-12, and the pyridine infrared phosphine content of the molecular sieve is 700-800 μmol / g at a desorption temperature of 200° C. Preferably, the molecular sieve has a pyridine infrared L acid / B acid content ratio of 70-120, preferably 80-100, at a desorption temperature of 200°C.

3. The molecular sieve according to claim 1, wherein The SiO2 / Al2O3 molar ratio of the molecular sieve is 2700-4000, preferably 3000-3500.

4. The molecular sieve according to any one of claims 1 to 3, wherein The molecular sieve has a nanometer-scale crystal size. Preferably, the molecular sieve has an average crystal size of 30-100 nm, preferably 50-70 nm.

5. The molecular sieve according to any one of claims 1 to 4, wherein The specific surface area of ​​the molecular sieve is 530-630m 2 / g, preferably 550-600m 2 / g; Preferably, the external specific surface area of ​​the molecular sieve is 130-180m 2 / g, preferably 145-165m 2 / g.

6. The molecular sieve according to any one of claims 1 to 5, wherein The pore volume of the molecular sieve is 0.32-0.43 mL / g, preferably 0.36-0.4 mL / g.

7. A method for preparing Sn-Beta molecular sieve, characterized in that: The method comprises the following steps: (1) Dealumination and tin supplementation reaction of HY molecular sieve with tin source to obtain Sn-Al-FAU molecular sieve; (2) in the presence of Beta zeolite seed crystals, the Sn-Al-FAU molecular sieve is crystallized to obtain Sn-Al-Beta molecular sieve; (3) The Sn-Al-Beta molecular sieve is dealuminated and then subjected to a tin supplementation treatment.

8. The method according to claim 7, wherein: In step (1), the SiO2 / Al2O3 molar ratio of the HY molecular sieve is 3.8-5, preferably 4.2-4.6; Preferably, the Na2O mass content of the HY molecular sieve is 0.5-1.5%, preferably 0.8-1.2%.

9. The method according to claim 7 or 8, wherein The dealumination and tin supplementation reaction in step (1) comprises: reacting the HY molecular sieve with a gaseous tin source under dealumination and tin supplementation reaction conditions; Preferably, the dealumination and tin supplementation reaction conditions include: reaction temperature of 400-600°C, preferably 450-550°C, time of 0.5-5h, preferably 2-3h; partial pressure of the tin source in the gas phase of 2.5kPa-7.5kPa, preferably 4kPa-6kPa; Preferably, the tin source is an anhydrous tin source, more preferably at least one of tin tetrachloride, trichloromethyltin, dimethyltin dichloride and trimethyltin chloride.

10. The method according to any one of claims 7 to 9, wherein: Step (2) comprises: mixing Beta zeolite seed crystals, a template, a silicon source, a Sn-Al-FAU molecular sieve and a solvent to obtain a mixed solution, then performing a crystallization reaction, and calcining the crystallized solid product; Preferably, the molar ratio of the materials in the mixed solution is SiO2: (0.03-0.09) Al2O3: (0.03-0.08) SnO2: (0.006-0.021) Na2O: (0.1-0.8) template: (3-8) H2O, preferably SiO2: (0.05-0.07) Al2O3: (0.05-0.07) SnO2: (0.009-0.018) Na2O: (0.4-0.6) template: (5-7) H2O; Preferably, the Beta zeolite seed crystals account for 3-10 wt % of the total silica in the mixed solution, preferably 6-8 wt %; Preferably, the SiO2 / Al2O3 molar ratio of the Beta zeolite seed crystals is 20-35, preferably 25-30.

11. The method according to claim 10, wherein: In step (2), the crystallization conditions include: a crystallization temperature of 138-145° C., preferably 140-142° C.; a crystallization time of 5-15 days, preferably 8-12 days; In step (2), the calcination conditions include: a calcination temperature of 500-600° C. and a calcination time of 4-8 hours.

12. The method according to any one of claims 7 to 11, wherein: The dealumination in step (3) comprises: reacting the Sn-Al-Beta molecular sieve with an acid solution; Preferably, the acid is selected from at least one of nitric acid, hydrochloric acid and sulfuric acid; Preferably, the concentration of the acid solution is 2.5-5 mol / L, preferably 3.5-4.5 mol / L; Preferably, the solid-liquid mass ratio of the Sn-Al-Beta molecular sieve to the acid solution is 1:30-1:100, preferably 1:50-1:70; Preferably, the conditions for reacting the Sn-Al-Beta molecular sieve with the acid solution include: temperature of 30-90° C., preferably 50-70° C.; time of 1-6 h, preferably 3-4 h; and number of times of 2-5 times, preferably 3-4 times.

13. The method according to any one of claims 7 to 12, wherein: The tin supplementation treatment in step (3) comprises: reacting the dealuminated molecular sieve with a gaseous tin source under tin supplementation treatment conditions; Preferably, the conditions of the tin supplementation treatment include: a reaction temperature of 400-550° C., preferably 450-500° C., a time of 2-7 hours, preferably 4-6 hours; a partial pressure of the tin source in the gas phase of 1 kPa-4 kPa, preferably 2 kPa-3 kPa; Preferably, the tin source is an anhydrous tin source, more preferably at least one of tin tetrachloride, trichloromethyltin, dimethyltin dichloride and trimethyltin chloride.

14. Use of the Sn-Beta molecular sieve according to any one of claims 1 to 6 in a cyclic ketone oxidation reaction, a saccharide isomerization reaction, a glucose to methyl lactate reaction, a lactic acid to L-lactide reaction, a propane dehydrogenation reaction, or a hydrogen transfer reaction between aldehydes, ketones, and alcohols, preferably in a cyclic ketone oxidation reaction, more preferably in a cyclohexanone oxidation reaction.

15. A method for the oxidation of a cyclic ketone, characterized in that: The method comprises: reacting a cyclic ketone with an oxidant in the presence of a solvent and a catalyst under oxidation reaction conditions; the catalyst is the Sn-Beta molecular sieve according to any one of claims 1 to 6; Preferably, the cyclic ketone is at least one of cyclohexanone, 2-adamantanone, dihydrocarvone and bicyclo[3.2.0]hept-2-en-6-one, more preferably cyclohexanone; Preferably, the oxidant is selected from at least one of tert-butyl hydroperoxide, hydrogen peroxide, cumene hydroperoxide, cyclohexyl hydroperoxide, peracetic acid and peroxypropionic acid, preferably hydrogen peroxide; Preferably, the amount of the cyclic ketone is 0.4-1.4 mmol relative to 1 mmol of the oxidant; Preferably, the amount of the catalyst is 10-25 mg relative to 1 mmol of the oxidant; Preferably, the oxidation reaction conditions include: oxidation reaction temperature of 75-95° C., and oxidation reaction time of 2-8 h.

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