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

Abstract

An Sn-Y type molecular sieve, a preparation method therefor and the use thereof, and an oxidation reaction method for a cyclic ketone. The surface silicon / tin molar ratio of the molecular sieve is 50-70, and the bulk silicon / tin molar ratio is 200-300; with respect to the Sn-Y type molecular sieve, Sn is mainly intensively distributed on the outer surface of a Y molecular sieve, thus achieving better catalytic performance for the Baeyer-Villiger oxidation reaction of a cyclic ketone.

Description

Sn-Y type 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. 202410187144.6 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-Y type molecular sieve, a preparation method and application thereof, and an oxidation reaction method of a cyclic ketone. Background Art

[0004] Heteroatom molecular sieves are molecular sieves containing other elements formed by isomorphously replacing some silicon, aluminum, or phosphorus atoms in the molecular sieve framework with other heteroatoms. Since the introduction of heteroatoms into the molecular sieve framework often causes a certain degree of change in the original structure and properties of the molecular sieve (such as acidity, particle size, pore properties, etc.), in recent years, it has gradually overcome the limitations on the use of traditional silicon-aluminum molecular sieves and broadened the application field of molecular sieves. The synthesis of heteroatom molecular sieves is also regarded as an important branch of the molecular sieve synthesis field with potential commercial value, and is currently receiving increasing attention.

[0005] Since the successful synthesis of TS-1 molecular sieve, researchers have prepared a variety of molecular sieves containing heteroatoms (such as tin, iron, gallium, zirconium, and vanadium). Among them, the synthesis of tin-based molecular sieves has attracted considerable attention. Because Sn is embedded in the molecular sieve framework, it provides unique Lewis acid centers, which can catalyze the Baeyer-Viiliger reaction of ketones. In 1997, Sn-beta molecular sieve was synthesized and, in 2001, was successfully used to catalyze the Baeyer-Viiliger reaction of cyclohexanone, with good selectivity for the product ε-caprolactone. However, since the Baeyer-Viiliger reaction of cyclohexanone typically uses a certain concentration of hydrogen peroxide as the oxidant, the reaction inevitably introduces water, which adsorbs on the active Sn centers, leading to decreased catalytic performance and increased byproducts. Therefore, in recent years, the use of solvents containing tert-butyl hydroperoxide as an oxidant has become a new direction. However, due to the large size of tert-butyl hydroperoxide molecules, the diffusion restriction effect of Sn-beta zeolites is more pronounced, making them less than ideal in practical applications. Y zeolites have more open pores and a supercage structure, leading to reports on the synthesis of Sn-Y zeolites in recent years.

[0006] Zhiguo Zhu et al. reported a method for synthesizing Sn-Y molecular sieves in "Postsynthesis and Effective Baeyer-Villiger Oxidation Properties of Hierarchical FAU-type Stannosilicates" in Volume 120 of the Journal of Physical Chemistry C. This method first prepares USY molecular sieves. USY powder is then placed in an aqueous solution of (NH4)2SnCl6, and hydrochloric acid is added to control the pH of the reaction. The reaction is stirred and allowed to react at a constant temperature for a period of time to produce the Sn-Y molecular sieve. However, the tin in the molecular sieve framework synthesized by this method is primarily distributed within the molecular sieve, which is not conducive to contact between the active sites of the Sn species and the reactant molecules during the reaction.

[0007] Zhiguo Zhu et al. reported a method for synthesizing Sn-Y molecular sieves in "Postsynthesis of FAU-type stannosilicate as efficient heterogeneous catalyst for Baeyer-Villiger oxidation," APPLIED CATALYSIS A-GENERAL, Volume 519. This method uses USY molecular sieve as the starting material. The USY is first treated with acid, and then Sn is implanted into the USY molecular sieve by reacting the dealuminated USY with SnCl4 at high temperature. However, the Sn atoms in the resulting Sn-Y molecular sieve are mostly distributed within the zeolite, and the Sn atoms are not fully exposed, which is detrimental to the contact between the active sites of the Sn species and the reactant molecules during the reaction. Summary of the Invention

[0008] To address the shortcomings of the prior art, the present invention provides a Sn-Y molecular sieve, its preparation method and application, and a method for the oxidation of cyclic ketones. The Sn in the Sn-Y molecular sieve provided by the present invention is primarily concentrated on the outer surface of the Y molecular sieve, resulting in improved activity and selectivity for the Baeyer-Villiger oxidation of cyclic ketones.

[0009] A first aspect of the present invention provides a Sn-Y molecular sieve, wherein the surface silicon-tin molar ratio of the molecular sieve is 50-70, and the bulk silicon-tin molar ratio is 200-300.

[0010] Preferably, the molecular sieve has a pyridine infrared phosphine content of 100-200 μmol / g, more preferably 130-170 μmol / g, at a desorption temperature of 200°C.

[0011] In the Sn-Y molecular sieve provided by the present invention, the framework Sn species are mainly concentrated on the outer surface of the Y molecular sieve, and the internal Sn species are relatively small, so that the Lewis acidic sites of the Sn-Y molecular sieve of the present invention are mainly concentrated on the surface of the molecular sieve, which has better accessibility to the reactant molecules and is almost not limited by the diffusion rate during the reaction process. The Sn species that provide Lewis acidic sites are efficiently utilized.

[0012] A second aspect of the present invention provides a method for preparing a Sn-Y molecular sieve, the method comprising the following steps:

[0013] 1) solid phase ion exchange of NaY molecular sieve with ammonium salt, followed by calcination to obtain HY molecular sieve;

[0014] 2) solid phase ion exchange of the HY molecular sieve with a tin source to obtain the Sn ion-exchanged Y molecular sieve;

[0015] 3) treating the Y molecular sieve after Sn ion exchange in a mixed gas containing water vapor and oxygen, and then performing an acid treatment.

[0016] The method provided by the present invention first utilizes ammonium salt and Na + Solid phase ion exchange was performed to remove Na + Exchanged to quaternary ammonium cations, which are converted to H + , and then continue to use solid-state ion exchange to 2+ The Sn ions are exchanged onto the outer surface of the Y molecular sieve. Subsequently, the Sn ions are exchanged onto the outer surface of the Y molecular sieve through high-temperature treatment with a mixture of water vapor and oxygen to form vacancies on the outer surface. The Sn ions are then inserted into the vacancies on the outer surface of the Y molecular sieve to form a four-coordinated framework Sn, ultimately achieving the goal of concentrating the distribution of Sn species with L acid on the outer surface of the molecular sieve.

[0017] The third aspect of the present invention provides the use of the Sn-Y molecular sieve described in the first aspect in the oxidation reaction of cyclic ketones.

[0018] 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-Y type molecular sieve described in the first aspect.

[0019] The Sn-Y 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-Y molecular sieve prepared by the present invention adopts this method, which is simple to operate, low in preparation cost, and can meet the needs of industrial production. DETAILED DESCRIPTION

[0020] 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.

[0021] In the present invention, unless otherwise explicitly stated, percentages and contents are all based on mass.

[0022] In a first aspect, the present invention provides a Sn-Y molecular sieve, wherein the surface silicon-tin molar ratio of the molecular sieve is 50-70, and the bulk silicon-tin molar ratio is 200-300. For example, the surface silicon-tin molar ratio of the molecular sieve is 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, more preferably 55-65. For example, the bulk silicon-tin molar ratio of the molecular sieve is 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, more preferably 230-280.

[0023] The Sn-Y type molecular sieve provided by the present invention has a smaller molar ratio of silicon to tin on the surface, and the tin species are mainly distributed on the outer surface of the molecular sieve, which is more conducive to improving the utilization rate of Sn. Moreover, when applied to the cyclic ketone oxidation reaction, it has higher catalytic performance.

[0024] In the present invention, the term "Sn-Y type molecular sieve" does not specifically limit the properties and structure of the product provided by the present invention. As long as the Y type molecular sieve contains Sn element and the surface silicon-tin molar ratio and the bulk silicon-tin molar ratio meet the requirements of the present invention, they are within the scope of protection of the present invention.

[0025] The crystal form of the molecular sieve can be determined by XRD characterization.

[0026] According to the present invention, preferably, the bulk SiO2 / Al2O3 molar ratio of the molecular sieve is 60-140, preferably 80-120, for example 80, 90, 100, 110 or 120.

[0027] According to the present invention, preferably, the surface SiO2 / Al2O3 molar ratio of the molecular sieve is 350-700, preferably 420-630, for example, 420, 450, 500, 530, 550, 580, 600 or 630.

[0028] In the present invention, the surface silicon-tin molar ratio and the surface silicon-aluminum molar ratio of the molecular sieve are characterized by X-ray photoelectron spectroscopy (XPS). Specifically, the XPS characterization is performed on a Kratos Axis ultra X-ray photoelectron spectrometer, with an Al Kα (1486.6 eV) excitation source. The XPS spectrum binding energy is corrected with C1s (284.8 eV), and then the silicon-tin molar ratio and the silicon-aluminum molar ratio on the molecular sieve surface are obtained by conversion.

[0029] In the present invention, the bulk silicon-tin molar ratio of the molecular sieve and the SiO2 / Al2O3 molar ratio of the molecular sieve are measured using inductively coupled plasma atomic emission spectroscopy (ICP-AES). Before testing, 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, made up 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 ratios (SiO2 / Al2O3) and silicon-tin molar ratios (SiO2 / SnO2).

[0030] According to the present invention, preferably, the molecular sieve has a pyridine infrared L-acid content of 100-200 μmol / g at a desorption temperature of 200°C, for example, 100 μmol / g, 110 μmol / g, 120 μmol / g, 130 μmol / g, 140 μmol / g, 150 μmol / g, 160 μmol / g, 170 μmol / g, 180 μmol / g, 190 μmol / g, 200 μmol / g, preferably 130-170 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.

[0031] According to the present invention, preferably, the molecular sieve has a pyridine infrared L-acid / B-acid content ratio of 90-130 at a desorption temperature of 200° C., for example, 90, 100, 110, 120, 130, and preferably 110-120. Using a molecular sieve with an appropriate L-acid / B-acid content ratio is more conducive to improving the conversion rate and target product selectivity during the reaction process.

[0032] In the present invention, the content of L acid and B acid in the molecular sieve is 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 sample is then heated to 200°C and vacuumed to remove the adsorbed pyridine molecules. The infrared spectrum of pyridine at this temperature is recorded. The infrared spectrum of pyridine at 1450cm -1 The peak at 1545 cm is attributed to the L acid absorption peak. -1The peak at is attributed to the absorption peak of Br(Ⅱ) acid. After integrating the peak area of ​​the spectrum, the infrared L(Ⅱ) acid and Br(Ⅱ) acid contents are obtained.

[0033] The quantitative calculation of L acid can be obtained by the following formula:

[0034] 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.

[0035] The quantitative calculation of B acid can be obtained by the following formula:

[0036] 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.

[0037] According to the present invention, preferably, the specific surface area of ​​the molecular sieve is 770-850m 2 / g, preferably 790-830m 2 / g.

[0038] According to the present invention, preferably, the pore volume of the molecular sieve is 0.36-0.43 mL / g, preferably 0.37-0.41 mL / g.

[0039] The molecular sieve provided by the present invention has a large specific surface area and a large pore volume. In the present invention, the 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 total pore volume is calculated at p / p 0 =0.98.

[0040] According to the present invention, preferably, the relative crystallinity of the molecular sieve is 86-96%, preferably 89-93%. The molecular sieve provided by the present invention has a higher crystallinity, which is more conducive to improving its performance in the catalytic oxidation reaction of cyclic ketones.

[0041] In the present invention, the relative crystallinity of the Sn-Y molecular sieve sample is determined by X-ray diffraction, specifically by the method of China's petrochemical industry standard SH / T 0340-92.

[0042] The molecular sieves having the aforementioned properties of the present invention can achieve the purpose of the present invention, and there are no special requirements 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 a Sn-Y type molecular sieve, the method comprising the following steps:

[0043] 1) solid phase ion exchange of NaY molecular sieve with ammonium salt, followed by calcination to obtain HY molecular sieve;

[0044] 2) solid phase ion exchange of the HY molecular sieve with a tin source to obtain the Sn ion-exchanged Y molecular sieve;

[0045] 3) treating the Y molecular sieve after Sn ion exchange in a mixed gas containing water vapor and oxygen, and then performing an acid treatment.

[0046] In the present invention, the NaY molecular sieve raw material can be a commercially available product or any NaY molecular sieve prepared according to existing techniques. Preferably, in step 1), the Na2O mass content in the NaY molecular sieve is 10.5-12%, preferably 10.8-11.7%. Preferably, the SiO2 / Al2O3 molar ratio of the NaY molecular sieve is 4.8-5.7, preferably 5.0-5.5.

[0047] According to the method provided by the present invention, the Na2O content in the molecular sieve is measured by X-ray fluorescence (XRF).

[0048] The present invention is wider to the selection range of described ammonium salt, as long as can carry out ammonium exchange with described NaY molecular sieve, described ammonium salt can be inorganic ammonium, can also be organic ammonium, can also be the mixture of the two, is preferably organic ammonium.In order to further improve the catalytic performance that makes molecular sieve, preferably, described ammonium salt is selected from least a in organic quaternary ammonium salt.The negatively charged ion of described organic quaternary ammonium salt can be halide ion, includes but not limited to bromide ion and / or chloride ion.The present invention is wider to the group selection range that is connected with N, for example can be the alkyl of C1-C5, and the four alkyls that are connected with N can be identical or different.

[0049] According to a preferred embodiment of the present invention, the ammonium salt is selected from at least one of tetramethylammonium bromide, tetramethylammonium chloride, tetraethylammonium bromide, tetraethylammonium chloride, tetrapropylammonium bromide, tetrapropylammonium chloride, propyltrimethylammonium bromide, and propyltrimethylammonium chloride, and more preferably tetramethylammonium bromide and / or tetramethylammonium chloride. This preferred embodiment is more conducive to preferentially exchanging sodium ions on the outer surface of the molecular sieve.

[0050] In the present invention, the solid phase ion exchange is used to exchange the Na ions of the NaY molecular sieve with the ammonium of the ammonium salt. The solid phase ion exchange has the conventional interpretation in the art, specifically refers to the ion exchange being carried out under solid phase conditions, and there is no solvent (such as water) during the exchange process. The inventors of the present invention have found in the course of research that by carrying out solid phase ion exchange between the NaY molecular sieve and the ammonium salt, the Na on the outer surface of the Y molecular sieve can be preferentially exchanged by controlling the solid phase ion exchange conditions. + Exchanging for quaternary ammonium cations, in conjunction with other steps of the present invention, is more conducive to achieving the purpose of concentrating the distribution of Sn species with L acid on the outer surface of the molecular sieve.

[0051] According to the present invention, preferably, the mass ratio of the ammonium salt to the NaY molecular sieve is 0.04-0.14, preferably 0.07-0.1.

[0052] According to a preferred embodiment of the present invention, in order to make the ammonium salt and the NaY molecular sieve mix more uniformly, the ammonium salt and the NaY molecular sieve are preferably ground under an inert atmosphere (eg, a glove box) before the solid phase ion exchange.

[0053] According to the present invention, preferably, the conditions for the solid-phase ion exchange in step 1) include: a reaction temperature of 140-190° C., preferably 160-170° C., and a reaction time of 60-180 min, preferably 100-140 min, under an inert atmosphere. The inert atmosphere is provided by an inert gas conventional in the art, preferably selected from nitrogen, helium, argon, or a mixture thereof in any proportion.

[0054] According to a specific embodiment of the present invention, the solid phase ion exchange is carried out under an inert gas circulation state.

[0055] According to a preferred embodiment of the present invention, step 1) of the method includes: placing NaY molecular sieve and ammonium salt in a reactor, introducing inert gas into one end of the reactor and emptying the other end, maintaining the inert gas circulation state in the reactor, and reacting at the temperature of solid phase ion exchange.

[0056] According to the present invention, there is no particular limitation on the specific manner of performing the solid phase ion exchange in step 1), which can be performed in a tubular furnace reactor.

[0057] Preferably, the method further comprises washing, filtering, and drying the solid product obtained by solid-phase ion exchange before the calcination in step 1). 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 technical means.

[0058] According to the present invention, the range of selection of the calcination conditions in step 1) is relatively wide, as long as the quaternary ammonium cation can be converted into H + Preferably, the calcination conditions in step 1) include: calcination temperature of 500-550°C and calcination time of 3-6 hours in an oxygen-containing atmosphere. The present invention has no particular limitation on the oxygen-containing atmosphere, and it can be air, for example.

[0059] According to the present invention, preferably, the method further comprises drying and / or calcining the NaY molecular sieve and the ammonium salt independently before the solid phase ion exchange. Drying and / or calcining the NaY molecular sieve and the ammonium salt to remove the water carried by the NaY molecular sieve and the ammonium salt is more conducive to ensuring that step 1) is carried out under anhydrous conditions. Preferably, the ammonium salt is dried and the NaY molecular sieve is calcined. More preferably, the conditions for calcining the NaY molecular sieve include: a calcination temperature of 500-550°C and a calcination time of 3-6h. More preferably, the conditions for drying the ammonium salt include: a drying temperature of 100-120°C and a drying time of 4-7h.

[0060] According to the present invention, in step 2), in order to make the HY molecular sieve and the tin source mix more uniformly, it is preferred that the HY molecular sieve and the tin source are ground under an inert atmosphere (eg, a glove box) before the solid phase ion exchange in step 2).

[0061] The specific operation mode and selection range of the solid phase ion exchange in step 2) can be the same as those described in step 1) and will not be repeated here.

[0062] According to the present invention, preferably, in step 2), the mass ratio of the tin source to the HY molecular sieve is 0.07-0.15, preferably 0.1-0.12. This preferred embodiment is more conducive to the Sn 2+ Exchanged to the outer surface of Y molecular sieve.

[0063] According to the present invention, preferably, the conditions for the solid phase ion exchange in step 2) include: a reaction temperature of 250-350° C., preferably 270-330° C., and a reaction time of 60-180 min, preferably 100-140 min, under an inert atmosphere. The inert atmosphere can be selected within the range as described above.

[0064] According to the present invention, preferably, the tin source is an anhydrous tin source, more preferably a divalent tin source, and further preferably at least one of stannous chloride, stannous sulfate and tin (II) acetate.

[0065] Preferably, the method further comprises washing, filtering, and drying the solid product obtained by solid-phase ion exchange in step 2) before 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.

[0066] According to the present invention, preferably, in step 3), the molar ratio of water vapor to oxygen in the mixed gas is 7-9, preferably 7.5-8.5. This preferred embodiment is more conducive to embedding tin into the Y molecular sieve framework.

[0067] According to the present invention, preferably, in step 3), the conditions for treating under a mixed gas containing water vapor and oxygen include: a reaction temperature of 550-650°C, preferably 580-620°C; a treatment time of 1-4h, preferably 2-3h; and a preferred total pressure of 0.05-0.15MPa, preferably 0.08-0.12MPa.

[0068] According to a preferred embodiment of the present invention, the Y molecular sieve after Sn ion exchange is treated in a mixed gas containing water vapor and oxygen, comprising: introducing a mixed gas of water vapor and oxygen into a reactor (e.g., a tubular furnace reactor), and then treating the Y molecular sieve after Sn ion exchange at a treatment temperature and pressure. After the treatment is completed, the gas is stopped, the Y molecular sieve is taken out after cooling, and the acid treatment is performed.

[0069] The specific conditions and operation methods of the acid treatment in step 3) are not particularly limited in the present invention. The acid treatment in step 3) can remove aluminum from the molecular sieve. The acid used in step 3) can be selected from a wide range of acids, including inorganic acids and / or organic acids, preferably inorganic acids. 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.

[0070] According to the present invention, preferably, the acid concentration used in the acid treatment is 0.2 mol / L-0.4 mol / L, preferably 0.25-0.35 mol / L.

[0071] According to the present invention, preferably, the acid treatment conditions include: a treatment temperature of 30-60°C, preferably 40-50°C; a treatment time of 60-180 minutes, preferably 100-140 minutes; and a solid-liquid mass ratio during the acid treatment of 1:6-1:12, preferably 1:8-1:10. The present invention does not particularly limit the number of acid treatments, and can be one or more, preferably one to two times.

[0072] Preferably, the method further comprises washing, filtering, and drying the solid product obtained from the acid treatment after the acid treatment 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.

[0073] According to the present invention, preferably, the conditions for solid-phase ion exchange of NaY molecular sieve with ammonium salt and solid-phase ion exchange of HY molecular sieve with tin source are such that the surface silicon-tin molar ratio of the prepared molecular sieve is 50-70 and the bulk silicon-tin molar ratio is 200-300.

[0074] The third aspect of the present invention provides the use of the Sn-Y molecular sieve described in the first aspect above in the oxidation reaction of cyclic ketones. The Sn-Y molecular sieve provided by the present invention has high performance in the oxidation reaction of cyclic ketones, in particular the Baeyer-Villiger oxidation reaction. Preferably, the Sn-Y molecular sieve is used in the Baeyer-Villiger oxidation reaction of cyclic ketones. The Sn-Y 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-ene-6-one, and preferably the Sn-Y molecular sieve is used in the oxidation reaction of cyclohexanone or 2-adamantanone.

[0075] 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-Y type molecular sieve described in the first aspect.

[0076] 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 and / or 2-adamantanone.

[0077] 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 tert-butyl hydroperoxide.

[0078] 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.

[0079] Preferably, the molar ratio of the oxidant to the cyclic ketone is 1:(1-3).

[0080] Preferably, the amount of the catalyst used is 80-600 mg, preferably 80-300 mg, relative to 1 mmol of the oxidant.

[0081] Preferably, the oxidation reaction conditions include: oxidation reaction temperature of 75-95° C., and oxidation reaction time of 2-8 h.

[0082] It should be noted that, in the present invention, unless otherwise explicitly stated, percentages and contents are all based on mass.

[0083] 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.

[0084] In the following examples and comparative examples of molecular sieves, the surface silicon-tin molar ratio is obtained by XPS testing, and the bulk silicon-tin molar ratio and the SiO2 / Al2O3 molar ratio of the molecular sieve are obtained by inductively coupled plasma atomic emission spectroscopy (ICP-AES) testing. The L acid and B acid contents of the molecular sieve are measured by pyridine-infrared spectroscopy. The specific surface area and pore volume of the molecular sieve are measured by N2-adsorption desorption method. The relative crystallinity of the molecular sieve is measured by China Petrochemical Industry Standard SH / T 0340-92 method. The Na2O content in the molecular sieve is measured by X-ray fluorescence (XRF). The specific conditions of each test method are as described in the specific implementation method section above and will not be repeated here.

[0085] Example 1

[0086] NaY molecular sieve (SiO2 / Al2O3 molar ratio of 4.8) with a Na2O content of 12.0% was calcined at 500°C for 3 hours, and tetramethylammonium bromide powder was dried at 110°C for 5 hours. Subsequently, the NaY molecular sieve and tetramethylammonium bromide powder were ground and mixed uniformly in a glove box, with the mass ratio of tetramethylammonium bromide to NaY molecular sieve controlled at 0.042. The solid was then loaded into a tubular furnace reactor, and helium was introduced into the tubular furnace to maintain an inert gas flow state in the reactor. After the gas in the reactor was replaced, the internal temperature was raised to 185°C and the reaction was carried out for 70 minutes. After the reaction was completed, the reaction was cooled in a helium atmosphere, removed, washed, filtered, and dried to obtain a Y molecular sieve after quaternary ammonium cation exchange.

[0087] The Y molecular sieve after quaternary ammonium cation exchange was calcined in air at 530°C for 4 hours to obtain HY molecular sieve. Subsequently, the HY molecular sieve and anhydrous stannous chloride powder were ground and mixed uniformly in a glove box. The mass ratio of anhydrous stannous chloride to HY molecular sieve was controlled at 0.07. The solid was then transferred to a tubular furnace reactor. Helium was introduced into the tubular furnace to maintain an inert gas flow state in the reactor. After the gas in the reactor was replaced, the internal temperature was raised to 345°C and reacted for 60 minutes. After the reaction was completed, the temperature was cooled in a helium atmosphere and then taken out. After washing, filtering, and drying, the Sn ion-exchanged Y molecular sieve Sn(II)Y was obtained.

[0088] The Sn(Ⅱ)Y molecular sieve was loaded into a tubular furnace reactor, and a mixed gas with a molar ratio of water vapor and oxygen of 7.0 was introduced. The reaction was carried out at 650°C for 1 hour, and the total pressure in the reactor was controlled to be 0.06 MPa. After the treatment was completed, the gas was stopped and the mixture was taken out after cooling to obtain the Sn-Y molecular sieve.

[0089] The obtained Sn-Y molecular sieve was placed in a hydrochloric acid solution with a concentration of 0.2 mol / L and a temperature of 60°C and treated for 170 minutes. The solid-liquid mass ratio was controlled at 1:12 during the treatment, and the treatment was performed once. After the treatment, the solid was filtered, washed, and dried at 130°C for 4 hours to obtain the final Sn-Y molecular sieve product.

[0090] Example 2

[0091] NaY molecular sieve (SiO2 / Al2O3 molar ratio of 5.7) with a Na2O content of 10.6% was calcined at 520°C for 4 hours, and tetramethylammonium bromide powder was dried at 110°C for 5 hours. The NaY molecular sieve and tetramethylammonium bromide powder were then ground and mixed in a glove box, with the mass ratio of tetramethylammonium bromide to NaY molecular sieve controlled at 0.13. The solid was then loaded into a tubular furnace reactor, which was then filled with helium to maintain an inert gas flow. After replacing the gas in the reactor, the internal temperature was raised to 144°C and the reaction was continued for 170 minutes. After the reaction was completed, the reaction was cooled in a helium atmosphere, removed, washed, filtered, and dried to obtain the Y molecular sieve after quaternary ammonium cation exchange.

[0092] The Y molecular sieve after quaternary ammonium cation exchange was calcined in air at 520°C for 5 hours to obtain HY molecular sieve. Subsequently, the HY molecular sieve and anhydrous stannous chloride powder were ground and mixed uniformly in a glove box. The mass ratio of anhydrous stannous chloride to HY molecular sieve was controlled at 0.14. The solid was then transferred to a tubular furnace reactor. Helium was introduced into the tubular furnace to maintain an inert gas flow state in the reactor. After the gas in the reactor was replaced, the internal temperature was raised to 260°C and the reaction was carried out for 177 minutes. After the reaction was completed, the temperature was cooled in a helium atmosphere and then removed. After washing, filtering, and drying, the Sn ion-exchanged Y molecular sieve Sn(II)Y was obtained.

[0093] The Sn(Ⅱ)Y molecular sieve was loaded into a tubular furnace reactor, and a mixed gas with a molar ratio of water vapor and oxygen of 8.8 was introduced. The reaction was carried out at 560°C for 3.5 hours, and the total pressure in the reactor was controlled to be 0.14 MPa. After the treatment was completed, the gas was stopped from being introduced, and the mixture was taken out after cooling to obtain the Sn-Y molecular sieve.

[0094] The obtained Sn-Y molecular sieve was placed in a nitric acid solution with a concentration of 0.4 mol / L and a temperature of 35°C for 90 minutes. The solid-liquid mass ratio was controlled at 1:7 during the treatment, and the treatment was performed twice. After the treatment, the solid was filtered, washed, and dried at 150°C for 4 hours to obtain the final Sn-Y molecular sieve product.

[0095] Example 3

[0096] NaY molecular sieve (SiO2 / Al2O3 molar ratio of 4.8) with a Na2O content of 12.0% was calcined at 550°C for 6 hours, and tetramethylammonium bromide powder was dried at 120°C for 5 hours. Subsequently, the NaY molecular sieve and tetramethylammonium bromide powder were ground and mixed uniformly in a glove box, with the mass ratio of tetramethylammonium bromide to NaY molecular sieve controlled at 0.11. The solid was then loaded into a tubular furnace reactor, which was then filled with helium to maintain an inert gas flow. After the gas in the reactor was replaced, the internal temperature was raised to 155°C and the reaction was carried out for 160 minutes. After the reaction was completed, the reaction was cooled in a helium atmosphere, removed, washed, filtered, and dried to obtain the Y molecular sieve after quaternary ammonium cation exchange.

[0097] The Y molecular sieve after quaternary ammonium cation exchange was calcined at 550°C in air for 6 hours to obtain HY molecular sieve. Subsequently, the HY molecular sieve and anhydrous stannous chloride powder were ground and mixed uniformly in a glove box. The mass ratio of anhydrous stannous chloride to HY molecular sieve was controlled at 0.09. The solid was then transferred to a tubular furnace reactor. Helium was introduced into the tubular furnace to maintain an inert gas flow state in the reactor. After the gas in the reactor was replaced, the internal temperature was raised to 340°C and the reaction was carried out for 80 minutes. After the reaction was completed, the temperature was cooled in a helium atmosphere and then taken out. After washing, filtering, and drying, the Sn ion-exchanged Y molecular sieve Sn(II)Y was obtained.

[0098] Sn(Ⅱ)Y molecular sieve was loaded into a tubular furnace reactor, and a mixed gas with a molar ratio of water vapor and oxygen of 7.2 was introduced. The reaction was carried out at 570°C for 4 hours, and the total pressure in the reactor was controlled to be 0.06 MPa. After the treatment was completed, the gas was stopped from being introduced, and the mixture was taken out after cooling to obtain Sn-Y molecular sieve.

[0099] The obtained Sn-Y molecular sieve was placed in a nitric acid solution with a concentration of 0.22 mol / L and a temperature of 55°C for 150 minutes. The solid-liquid mass ratio was controlled at 1:11 during the treatment. The treatment was performed twice in total. After the treatment, the solid was filtered, washed, and dried at 150°C for 4 hours to obtain the final Sn-Y molecular sieve product.

[0100] Example 4

[0101] NaY molecular sieve (SiO2 / Al2O3 molar ratio of 5.3) with a Na2O content of 11.0% was calcined at 530°C for 5 hours, and tetramethylammonium bromide powder was dried at 110°C for 6 hours. Subsequently, the NaY molecular sieve and tetramethylammonium bromide powder were ground and mixed uniformly in a glove box, with the mass ratio of tetramethylammonium bromide to NaY molecular sieve controlled at 0.08. The solid was then loaded into a tubular furnace reactor, and helium was introduced into the tubular furnace to maintain an inert gas flow in the reactor. After the gas in the reactor was replaced, the internal temperature was raised to 162°C and the reaction was carried out for 140 minutes. After the reaction was completed, the reaction was cooled in a helium atmosphere, removed, washed, filtered, and dried to obtain the Y molecular sieve after quaternary ammonium cation exchange.

[0102] The Y molecular sieve after quaternary ammonium cation exchange was calcined in air at 530°C for 5 hours to obtain HY molecular sieve. Subsequently, the HY molecular sieve and anhydrous stannous chloride powder were ground and mixed uniformly in a glove box. The mass ratio of anhydrous stannous chloride to HY molecular sieve was controlled at 0.10. The solid was then transferred to a tubular furnace reactor. Helium was introduced into the tubular furnace to maintain an inert gas flow state in the reactor. After the gas in the reactor was replaced, the internal temperature was raised to 330°C and the reaction was carried out for 110 minutes. After the reaction was completed, the temperature was cooled in a helium atmosphere and then taken out. After washing, filtering, and drying, the Sn ion-exchanged Y molecular sieve Sn(II)Y was obtained.

[0103] The Sn(Ⅱ)Y molecular sieve was loaded into a tubular furnace reactor, and a mixed gas with a molar ratio of water vapor and oxygen of 8.3 was introduced. The reaction was carried out at 615°C for 3 hours, and the total pressure in the reactor was controlled to be 0.09 MPa. After the treatment was completed, the gas was stopped and the mixture was taken out after cooling to obtain the Sn-Y molecular sieve.

[0104] The obtained Sn-Y molecular sieve was placed in a sulfuric acid solution with a concentration of 0.28 mol / L and a temperature of 43°C for 140 minutes. The solid-liquid mass ratio was controlled at 1:10 during the treatment, and the treatment was performed once. After the treatment, the solid was filtered, washed, and dried at 140°C for 5 hours to obtain the final Sn-Y molecular sieve product.

[0105] Example 5

[0106] NaY molecular sieve (SiO2 / Al2O3 molar ratio of 5.2) with a Na2O content of 11.5% was calcined at 520°C for 5 hours, and tetramethylammonium bromide powder was dried at 110°C for 5 hours. Subsequently, the NaY molecular sieve and tetramethylammonium bromide powder were ground and mixed uniformly in a glove box, with the mass ratio of tetramethylammonium bromide to NaY molecular sieve controlled at 0.10. The solid was then loaded into a tubular furnace reactor, and helium was introduced into the tubular furnace to maintain an inert gas flow in the reactor. After the gas in the reactor was replaced, the internal temperature was raised to 170°C and the reaction was carried out for 110 minutes. After the reaction was completed, the reaction was cooled in a helium atmosphere, removed, washed, filtered, and dried to obtain the Y molecular sieve after quaternary ammonium cation exchange.

[0107] The Y molecular sieve after quaternary ammonium cation exchange was calcined in air at 530°C for 5 hours to obtain HY molecular sieve. Subsequently, the HY molecular sieve and anhydrous stannous chloride powder were ground and mixed uniformly in a glove box. The mass ratio of anhydrous stannous chloride to HY molecular sieve was controlled at 0.12. The solid was then transferred to a tubular furnace reactor. Helium was introduced into the tubular furnace to maintain an inert gas flow state in the reactor. After the gas in the reactor was replaced, the internal temperature was raised to 290°C and the reaction was carried out for 135 minutes. After the reaction was completed, the temperature was cooled in a helium atmosphere and then removed. After washing, filtering, and drying, the Sn ion-exchanged Y molecular sieve Sn(II)Y was obtained.

[0108] The Sn(Ⅱ)Y molecular sieve was loaded into a tubular furnace reactor, and a mixed gas with a molar ratio of water vapor and oxygen of 7.7 was introduced. The reaction was carried out at 585°C for 2 hours. The total pressure in the reactor was controlled to be 0.12 MPa. After the treatment was completed, the gas was stopped and the mixture was taken out after cooling to obtain the Sn-Y molecular sieve.

[0109] The obtained Sn-Y molecular sieve was placed in a hydrochloric acid solution with a concentration of 0.35 mol / L and a temperature of 50°C and treated for 105 minutes. The solid-liquid mass ratio was controlled at 1:8 during the treatment, and the treatment was performed twice in total. After the treatment, the solid was filtered, washed, and dried at 140°C for 5 hours to obtain the final Sn-Y molecular sieve product.

[0110] Comparative Example 1

[0111] NaY molecular sieve (SiO2 / Al2O3 molar ratio of 4.8) with a Na2O content of 12.0% was calcined at 500°C for 3 hours, and tetramethylammonium bromide powder was dried at 110°C for 5 hours. The NaY molecular sieve was then added to distilled water at a mass ratio of 1:10, followed by the addition of tetramethylammonium bromide at a mass ratio of 0.042 to the NaY molecular sieve. Ion exchange was then performed once at 90°C for 70 minutes. After filtration, washing, and drying, the quaternary ammonium cation-exchanged Y molecular sieve was obtained.

[0112] The Y molecular sieve after quaternary ammonium cation exchange was calcined in air at 530°C for 4 hours to obtain HY molecular sieve. Subsequently, the HY molecular sieve and anhydrous stannous chloride powder were ground and mixed uniformly in a glove box. The mass ratio of anhydrous stannous chloride to HY molecular sieve was controlled at 0.07. The solid was then transferred to a tubular furnace reactor. Helium was introduced into the tubular furnace to maintain an inert gas flow state in the reactor. After the gas in the reactor was replaced, the internal temperature was raised to 345°C and reacted for 60 minutes. After the reaction was completed, the temperature was cooled in a helium atmosphere and then taken out. After washing, filtering, and drying, the Sn ion-exchanged Y molecular sieve Sn(II)Y was obtained.

[0113] The Sn(Ⅱ)Y molecular sieve was loaded into a tubular furnace reactor, and a mixed gas with a molar ratio of water vapor and oxygen of 7.0 was introduced. The reaction was carried out at 650°C for 1 hour, and the total pressure in the reactor was controlled to be 0.06 MPa. After the treatment was completed, the gas was stopped and the mixture was taken out after cooling to obtain the Sn-Y molecular sieve.

[0114] The obtained Sn-Y molecular sieve was placed in a hydrochloric acid solution with a concentration of 0.2 mol / L and a temperature of 60°C and treated for 170 minutes. The solid-liquid mass ratio was controlled at 1:12 during the treatment, and the treatment was performed once. After the treatment, the solid was filtered, washed, and dried at 130°C for 4 hours to obtain the final Sn-Y molecular sieve product.

[0115] Comparative Example 2

[0116] NaY molecular sieve (SiO2 / Al2O3 molar ratio of 4.8) with a Na2O content of 12.0% was calcined at 500°C for 3 hours, and tetramethylammonium bromide powder was dried at 110°C for 5 hours. Subsequently, the NaY molecular sieve and tetramethylammonium bromide powder were ground and mixed uniformly in a glove box, with the mass ratio of tetramethylammonium bromide to NaY molecular sieve controlled at 0.042. The solid was then loaded into a tubular furnace reactor, and helium was introduced into the tubular furnace to maintain an inert gas flow state in the reactor. After the gas in the reactor was replaced, the internal temperature was raised to 185°C and the reaction was carried out for 70 minutes. After the reaction was completed, the reaction was cooled in a helium atmosphere, removed, washed, filtered, and dried to obtain a Y molecular sieve after quaternary ammonium cation exchange.

[0117] The Y molecular sieve, after quaternary ammonium cation exchange, was calcined in air at 530°C for 4 hours to obtain the HY molecular sieve. The HY molecular sieve was then placed in a stannous chloride solution with a mass ratio of anhydrous stannous chloride to HY molecular sieve of 0.07 and a solid-liquid mass ratio of the molecular sieve to the stannous chloride solution of 1:5. The exchange was carried out at 90°C for 2 hours. After the ion exchange, the solid was filtered, washed, and dried to obtain the Sn ion-exchanged Y molecular sieve, Sn(II)Y.

[0118] The Sn(Ⅱ)Y molecular sieve was loaded into a tubular furnace reactor, and a mixed gas with a molar ratio of water vapor and oxygen of 7.0 was introduced. The reaction was carried out at 650°C for 1 hour, and the total pressure in the reactor was controlled to be 0.06 MPa. After the treatment was completed, the gas was stopped and the mixture was taken out after cooling to obtain the Sn-Y molecular sieve.

[0119] The obtained Sn-Y molecular sieve was placed in a hydrochloric acid solution with a concentration of 0.2 mol / L and a temperature of 60°C and treated for 170 minutes. The solid-liquid mass ratio was controlled at 1:12 during the treatment, and the treatment was performed once. After the treatment, the solid was filtered, washed, and dried at 130°C for 4 hours to obtain the final Sn-Y molecular sieve product.

[0120] Comparative Example 3

[0121] NaY molecular sieve (SiO2 / Al2O3 molar ratio of 4.8) with a Na2O content of 12.0% was calcined at 500°C for 3 hours, and tetramethylammonium bromide powder was dried at 110°C for 5 hours. Subsequently, the NaY molecular sieve and tetramethylammonium bromide powder were ground and mixed uniformly in a glove box, with the mass ratio of tetramethylammonium bromide to NaY molecular sieve controlled at 0.042. The solid was then loaded into a tubular furnace reactor, and helium was introduced into the tubular furnace to maintain an inert gas flow state in the reactor. After the gas in the reactor was replaced, the internal temperature was raised to 185°C and the reaction was carried out for 70 minutes. After the reaction was completed, the reaction was cooled in a helium atmosphere, removed, washed, filtered, and dried to obtain a Y molecular sieve after quaternary ammonium cation exchange.

[0122] The Y molecular sieve after quaternary ammonium cation exchange was calcined in air at 530°C for 4 hours to obtain HY molecular sieve. The HY molecular sieve was placed in a tubular furnace reactor, steam was introduced, and the reaction was carried out at 650°C for 1 hour. The total pressure in the reactor was controlled to be 0.06MPa. After the treatment, the gas was stopped and the sieve was taken out after cooling to obtain H-USY molecular sieve.

[0123] The obtained H-USY molecular sieve was placed in a hydrochloric acid solution with a concentration of 0.2 mol / L and a temperature of 60°C for treatment for 170 minutes. The solid-liquid mass ratio was controlled at 1:12 during the treatment, and the treatment was performed once. After the treatment, the solid was filtered, washed, and dried at 130°C for 4 hours to obtain the dealuminated H-USY molecular sieve.

[0124] The dealuminated H-USY molecular sieve was placed in a (NH4)2SnCl6 solution, the mass ratio of (NH4)2SnCl6 and HY molecular sieve in the solution was controlled at 0.07, the solid-liquid mass ratio was 1:80, a certain amount of hydrochloric acid was added, the concentration of hydrochloric acid in the solution was controlled at 0.1 mol / L, the reaction was carried out at 70°C for 24 hours, and then the Sn-Y molecular sieve was obtained after filtration, drying, and calcination at 550°C for 4 hours.

[0125] The structural properties of the molecular sieves prepared in the above examples and comparative examples are listed in Table 1 below.

[0126] Table 1 Note: In Table 1, the silicon-aluminum ratio refers to the SiO2 / Al2O3 molar ratio

[0127] Table 1 Note: In Table 1, the silicon-aluminum ratio refers to the molar ratio of SiO2 / Al2O3

[0128] Test Example 1

[0129] This test example is used to illustrate the performance of the molecular sieve provided by the present invention in the Baeyer-Villiger oxidation reaction of cyclohexanone.

[0130] The performance of the Sn-Y molecular sieves in the examples and comparative examples was evaluated by the Baeyer-Villiger oxidation reaction of cyclohexanone and tert-butyl hydroperoxide (TBHP). The reaction was carried out in a round-bottom flask with a condensed water cooling device. 250 mg of catalyst was weighed and added to the flask, followed by the addition of 5 mmol of cyclohexanone, 3 mmol of TBHP (3.0 mol / L decane solution), and 10 mL of 1,4-dioxane (solvent). The reaction solution was placed in an 85 ° C oil bath for 5 h. After the reaction was completed, it was transferred to ice water and cooled to room temperature. 0.4 g of chlorobenzene was added as an internal standard, stirred evenly, and then centrifuged. The supernatant was analyzed by gas chromatograph for cyclohexanone conversion, selectivity of the target product ε-caprolactone, and yield. The evaluation results are given in Table 2.

[0131] Table 2

[0132] Test Example 2

[0133] This test example is used to illustrate the performance of the molecular sieve provided by the present invention in the Baeyer-Villiger oxidation reaction of 2-adamantanone.

[0134] The performance of the Sn-Y molecular sieves in the examples and comparative examples was evaluated by the Baeyer-Villiger oxidation reaction of 2-adamantanone and tert-butyl hydroperoxide (TBHP). The reaction was carried out in a round-bottom flask with a condensed water cooling device. 550 mg of catalyst was weighed and added to the flask, followed by the addition of 4 mmol of 2-adamantanone, 3 mmol of TBHP (6.0 mol / L decane solution), and 10 mL of 1,4-dioxane (solvent). The reaction solution was placed in an oil bath at 93 ° C for 3 h. After the reaction was completed, it was transferred to ice water and cooled to room temperature. 0.4 g of cyclohexanone was added as an internal standard, stirred evenly, and then centrifuged. The supernatant was analyzed by gas chromatograph for 2-adamantanone conversion, selectivity of the target product lactone, and yield. The evaluation results are given in Table 3.

[0135] Table 3

[0136] Combining the product properties in Table 1 with the evaluation results in Tables 2 and 3, it can be seen that the Sn active species of the Sn-Y molecular sieve provided by the present invention are primarily distributed on the outer surface of the molecular sieve and have a high L-acid content. When catalyzing the oxidation reaction of cyclohexanone, this molecular sieve is beneficial in improving the conversion of cyclohexanone and the selectivity for the target product ε-caprolactone, resulting in a high ε-caprolactone yield. It also exhibits high activity and selectivity in the oxidation reaction of 2-adamantanone, demonstrating excellent catalytic performance.

Claims

1. A Sn-Y type molecular sieve, characterized in that The surface silicon-tin molar ratio of the molecular sieve is 50-70, and the bulk silicon-tin molar ratio is 200-300.

2. The molecular sieve according to claim 1, wherein The surface silicon-tin molar ratio of the molecular sieve is 55-65, and the bulk silicon-tin molar ratio is 230-280; Preferably, the bulk SiO2 / Al2O3 molar ratio of the molecular sieve is 60-140, preferably 80-120; Preferably, the surface SiO2 / Al2O3 molar ratio of the molecular sieve is 350-700, preferably 420-630.

3. The molecular sieve according to claim 1, wherein The molecular sieve has a pyridine infrared phosphodiester acid content of 100-200 μmol / g, preferably 130-170 μmol / g, at a desorption temperature of 200°C.

4. The molecular sieve according to claim 1, wherein The molecular sieve has a pyridine infrared L acid / B acid content ratio of 90-130, preferably 110-120, at a desorption temperature of 200°C.

5. The molecular sieve according to claim 1, wherein The specific surface area of ​​the molecular sieve is 770-850m 2 / g, preferably 790-830m 2 / g; And / or, the molecular sieve pore volume is 0.36-0.43 mL / g, preferably 0.37-0.41 mL / g.

6. The molecular sieve according to any one of claims 1 to 5, wherein The relative crystallinity of the molecular sieve is 86-96%, preferably 89-93%.

7. A method for preparing a Sn-Y type molecular sieve, characterized in that: The method comprises the following steps: 1) solid phase ion exchange of NaY molecular sieve with ammonium salt, followed by calcination to obtain HY molecular sieve; 2) solid phase ion exchange of the HY molecular sieve with a tin source to obtain the Sn ion-exchanged Y molecular sieve; 3) treating the Y molecular sieve after Sn ion exchange in a mixed gas containing water vapor and oxygen, and then performing an acid treatment.

8. The method according to claim 7, wherein: In step 1), the mass content of Na2O in the NaY molecular sieve is 10.5-12%, preferably 10.8-11.7%; Preferably, the SiO2 / Al2O3 molar ratio of the NaY molecular sieve is 4.8-5.7, preferably 5-5.

5.

9. The method according to claim 7, wherein: The ammonium salt is selected from at least one of organic quaternary ammonium salts, preferably at least one of tetramethylammonium bromide, tetramethylammonium chloride, tetraethylammonium bromide, tetraethylammonium chloride, tetrapropylammonium bromide, tetrapropylammonium chloride, propyltrimethylammonium bromide and propyltrimethylammonium chloride, more preferably tetramethylammonium bromide and / or tetramethylammonium chloride.

10. The method according to any one of claims 7 to 9, wherein: The mass ratio of the ammonium salt to the NaY molecular sieve is 0.04-0.14, preferably 0.07-0.1; Preferably, the conditions of the solid phase ion exchange in step 1) include: under an inert atmosphere, a reaction temperature of 140-190° C., preferably 160-170° C., and a reaction time of 60-180 min, preferably 100-140 min; Preferably, the calcination conditions in step 1) include: calcination temperature of 500-550° C. and calcination time of 3-6 h in an oxygen-containing atmosphere; Preferably, the method further comprises drying and / or calcining the NaY molecular sieve and the ammonium salt independently before performing the solid phase ion exchange.

11. The method according to any one of claims 7 to 10, wherein: In step 2), the mass ratio of the tin source to the HY molecular sieve is 0.07-0.15, preferably 0.1-0.12; Preferably, the conditions of the solid phase ion exchange in step 2) include: under an inert atmosphere, a reaction temperature of 250-350° C., preferably 270-330° C., and a reaction time of 60-180 min, preferably 100-140 min; Preferably, the tin source is an anhydrous tin source, more preferably a divalent tin source, further preferably at least one of stannous chloride, stannous sulfate and tin (II) acetate.

12. The method according to any one of claims 7 to 11, wherein: In step 3), the molar ratio of water vapor to oxygen in the mixed gas is 7-9, preferably 7.5-8.5; Preferably, in step 3), the conditions for treatment under a mixed gas containing water vapor and oxygen include: reaction temperature of 550-650°C, preferably 580-620°C; treatment time of 1-4h, preferably 2-3h; preferably total pressure of 0.05-0.15MPa, preferably 0.08-0.12MPa.

13. The method according to any one of claims 7 to 12, wherein: In step 3), the acid is an inorganic acid and / or an organic acid, the inorganic acid is preferably at least one of nitric acid, hydrochloric acid, and sulfuric acid, and the organic acid is preferably at least one of citric acid, oxalic acid, EDTA, and tartaric acid; Preferably, the acid concentration used in the acid treatment is 0.2mol / L-0.4mol / L, preferably 0.25-0.35mol / L; Preferably, the acid treatment conditions include: treatment temperature of 30-60°C, preferably 40-50°C; treatment time of 60-180 min, preferably 100-140 min; solid-liquid mass ratio during acid treatment of 1:6-1:12, preferably 1:8-1:

10.

14. Use of the Sn-Y molecular sieve according to any one of claims 1 to 6 in the oxidation reaction of cyclic ketones, preferably in the oxidation reaction of at least one of cyclohexanone, 2-adamantanone, dihydrocarvone and bicyclo[3,2,0]hept-2-en-6-one.

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-Y type 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 and / or 2-adamantanone; 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 tert-butyl hydroperoxide; Preferably, the molar ratio of the oxidant to the cyclic ketone is 1:(1-3); Preferably, the amount of catalyst used is 80-600 mg relative to 1 mmol of 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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