Tin-containing molecular sieve, method for preparing the same, and use thereof

Abstract

The present disclosure relates to a tin-containing molecular sieve, a preparation method and application thereof, the method comprising: contacting a raw material molecular sieve with a liquid mixture containing a tin source, a polyol and a solvent to obtain a tin-containing precursor molecular sieve; wherein the raw material molecular sieve has a framework hydroxyl vacancy; and treating the tin-containing precursor molecular sieve under a vapor condition, and then drying and calcining to obtain the tin-containing molecular sieve. The present disclosure can effectively increase the framework tin content of the molecular sieve, while inhibiting the generation of non-framework tin, significantly improving the catalytic activity and selectivity of the molecular sieve, and the process is simple, the synthesis conditions are mild, and has good industrial application prospects.

Description

Technical Field

[0001] This disclosure relates to the field of inorganic catalytic material preparation, specifically to a tin-containing molecular sieve, its preparation method, and its application. Background Technology

[0002] Tin-containing molecular sieves, due to the Lewis acidity of their framework tin atoms, have wide applications in catalytic ring-opening reactions of epoxides, Baeyer-Villiger oxidation reactions, and Meerwein-Ponndorf-Verley (MPV) reactions. Existing methods for synthesizing tin-containing molecular sieves mainly include direct synthesis and post-synthesis methods, both of which have certain limitations. Direct synthesis typically employs a hydrothermal route, with harsh synthesis conditions, long crystallization times, and usually requires the addition of fluorine-containing mineralizing agents. Furthermore, the framework tin content is relatively low, affecting catalytic activity and selectivity. Post-synthesis methods, by removing some framework atoms and introducing a tin source, offer advantages such as milder synthesis conditions and simpler processes. However, existing post-synthesis methods generally suffer from high non-framework tin content. These non-framework tin species are prone to aggregation, potentially clogging the molecular sieve channels, reducing catalytic activity, and may also trigger side reactions, decreasing the selectivity of the catalytic reaction. Summary of the Invention

[0003] The purpose of this disclosure is to provide a tin-containing molecular sieve, its preparation method, and its application, so as to improve the catalytic activity and selectivity of the tin-containing molecular sieve.

[0004] To achieve the above objectives, the first aspect of this disclosure provides a method for preparing a tin-containing molecular sieve, the method comprising: The raw material molecular sieve is contacted with a liquid mixture containing a tin source, a polyol, and a solvent to obtain a tin-containing precursor molecular sieve; wherein the raw material molecular sieve has skeletal hydroxyl vacancies. The tin-containing precursor molecular sieve was treated under steam conditions, then dried and calcined to obtain the tin-containing molecular sieve.

[0005] Optionally, in the infrared hydroxyl spectrum of the raw material molecular sieve, the wavenumber is around 3735 cm⁻¹. -1 The characteristic peak intensity and wavenumber near 3550 cm⁻¹ -1 The ratio of the intensity of the nearby characteristic peaks I 3735 / I 3550 4~10; and / or, The raw material molecular sieve has at least one of the following framework structures: MFI, MEL, BEA, MOR, MWW, STT, and SVR.

[0006] Optionally, the tin source includes at least one of dimethyltin dichloride, tin acetate, stannous acetate, dibutyltin diacetate, alkoxytin chloride, tin tetrachloride pentahydrate, anhydrous tin tetrachloride, stannous chloride, and stannous chloride dihydrate.

[0007] Optionally, the polyol includes at least one of ethylene glycol, propylene glycol, glycerol, butanediol, pentanediol, hexanediol, butanetetrol, pentaerythritol, cyclopentanediol, cyclohexanediol, hydroquinone, trioses, tetraoses, pentoses, and hexoses.

[0008] Optionally, the solvent includes at least one of water, methanol, ethanol, propanol, and acetone.

[0009] Optionally, the molar ratio of the tin source, the polyol, and the solvent is 1:(1~10):(1~10); and / or, The molar ratio of the molecular sieve raw material to the tin source, calculated as Si, is 1:(0.005~0.10).

[0010] Optionally, the contact conditions include: a temperature of 20~100℃, a pressure of -0.01~1MPa, and a time of 0.01~24h.

[0011] Optionally, the steam atmosphere used in the steam conditions is water vapor and / or organic compound vapor, preferably water vapor; Optionally, the steam conditions include: a temperature of 100~300℃, a pressure of 0~1.5MPa, and a time of 0.1~5h.

[0012] Optionally, the drying conditions include: a temperature of 60~200℃ and a time of 0.5~12h; and / or, The roasting conditions include a temperature of 300~700℃ and a time of 0.5~12h.

[0013] A second aspect of this disclosure provides a tin-containing molecular sieve prepared by the method described in the first aspect of this disclosure; Optionally, in the X-ray photoelectron spectroscopy of the tin-containing molecular sieve, the 3d... 5 / 2 The signal peak is located at 488.0±0.3eV, and the framework tetracoordinate tin content of the tin-containing molecular sieve is not less than 90% by weight.

[0014] In a third aspect, this disclosure provides the application of the tin-containing molecular sieve described in the second aspect of this disclosure in catalyzing the ring-opening reaction of epoxides; Optionally, the application includes using the tin-containing molecular sieve as a catalyst to catalyze a ring-opening reaction between an epoxy compound and water or an alcohol.

[0015] Through the above technical solution, this disclosure adopts a molecular sieve with skeletal hydroxyl vacancies and optimizes the synthesis process, which can effectively increase the skeletal tin content of the molecular sieve, improve the raw material utilization rate, inhibit the formation of non-skeletal tin, reduce the migration and aggregation of tin species, avoid pore blockage, maintain the good pore structure of the molecular sieve, significantly improve the catalytic activity and selectivity of the molecular sieve, and the process is simple, the synthesis conditions are mild, and there is no need to use strong acids or fluorine-containing mineralizers, which has good prospects for industrial application.

[0016] Other features and advantages of this disclosure will be described in detail in the following detailed description section. Attached Figure Description

[0017] The accompanying drawings are provided to further illustrate the present disclosure and form part of the specification. They are used together with the following detailed description to explain the present disclosure, but do not constitute a limitation thereof. In the drawings: Figure 1 The image shows the XRD pattern of BEA molecular sieve raw material A used in the examples.

[0018] Figure 2 The image shows the FT-IR spectrum of BEA molecular sieve raw material A used in the examples.

[0019] Figure 3 The image shows the XRD pattern of the tin-containing BEA molecular sieve prepared in Example 1.

[0020] Figure 4 The 3d tin species of the tin-containing BEA molecular sieve prepared in Example 1 5 / 2 XPS spectrum.

[0021] Figure 5 The XRD pattern of the tin-containing STT molecular sieve prepared in Example 8 is shown.

[0022] Figure 6 For the tin species of tin-containing BEA molecular sieve prepared in Comparative Example 1, 3d 5 / 2 XPS spectrum. Detailed Implementation

[0023] The specific embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit this disclosure.

[0024] In a first aspect, this disclosure provides a method for preparing a tin-containing molecular sieve, the method comprising the following steps S1-S2: S1. The raw material molecular sieve is contacted with a liquid mixture containing a tin source, a polyol, and a solvent to obtain a tin-containing precursor molecular sieve; wherein the raw material molecular sieve has skeletal hydroxyl vacancies; S2. The tin-containing precursor molecular sieve is treated under steam conditions, then dried and calcined to obtain the tin-containing molecular sieve.

[0025] In step S1, the raw material molecular sieve has skeletal hydroxyl vacancies, meaning that the Al sites in the molecular sieve skeleton are missing, forming defect sites compensated by hydroxyl groups (-OH). Specifically, in the infrared hydroxyl spectrum of the molecular sieve, at 3550 cm⁻¹... -1 The nearby signal peak can characterize the hydroxyl group, 3735 cm⁻¹ -1 The nearby signal peaks can characterize the terminal hydroxyl groups; the infrared hydroxyl spectrum of the raw material molecular sieve at a wavenumber of 3550 cm⁻¹ -1 The vicinity exhibits characteristic peaks; furthermore, in the infrared hydroxyl spectrum of the raw material molecular sieve, the wavenumber is around 3735 cm⁻¹. -1 The characteristic peak intensity and wavenumber near 3550 cm⁻¹ -1 The ratio of the intensity of the nearby characteristic peaks I 3735 / I 3550 (Based on peak height) can be 4~10. The silicon-to-aluminum atomic ratio of the raw material molecular sieve can be 5~800.

[0026] The raw material molecular sieve is preferably a molecular sieve obtained by post-processing a parent molecular sieve to remove some framework atoms. The post-processing can be a method commonly used in the art, such as acid treatment, alkali treatment, alternating acid-alkali treatment, microwave treatment, solvent treatment, high-temperature treatment, steam treatment, or a combination of the above methods. This disclosure does not limit the methods used, and specific post-processing methods are well-known in the art and will not be elaborated upon here. The parent molecular sieve can be aluminosilicate molecular sieve, gallium silicate molecular sieve, borosilicate molecular sieve, germanium silicate molecular sieve, etc.

[0027] There are no restrictions on the type of molecular sieve framework structure of the raw material; it can be any molecular sieve framework structure type published by the International Molecular Sieve Association (IZA). Preferably, the raw material molecular sieve has at least one of the following framework structures: MFI, MEL, BEA, MOR, MWW, STT, and SVR. More preferably, it has at least one of the following framework structures: BEA, MWW, and STT.

[0028] The tin source can be an organotin source and / or an inorganic tin source. Specifically, the organotin source can be dimethyltin dichloride, tin acetate, stannous acetate, dibutyltin diacetate, alkoxytin chloride, etc.; the general formula of the alkoxytin chloride is (RO). n SnCl 4-nWhere R can be any alkyl group, and n is a positive integer from 1 to 3, the alkoxytin chloride can be obtained by reacting tin tetrachloride with an alcohol, or by reacting tin tetrachloride with a tetraalkyl stannate. For example, the alkoxytin chloride can be monomethoxytin trichloride, dimethoxytin dichloride, trimethoxytin monochloride, monoethoxytin trichloride, diethoxytin dichloride, triethoxytin monochloride, monopropoxytin trichloride, dipropoxytin dichloride, tripropoxytin monochloride, etc. The inorganic tin source can include tin tetrachloride pentahydrate, anhydrous tin tetrachloride, stannous chloride, stannous chloride dihydrate, etc.

[0029] In one specific embodiment, the tin source includes at least one of tin acetate, stannous acetate, alkoxystannous chloride, stannous tetrachloride pentahydrate, anhydrous stannous tetrachloride, stannous chloride, and stannous chloride dihydrate. Preferably, it includes at least one of tin acetate, stannous acetate, ethoxystannous trichloride, diethoxystannous dichloride, triethoxystannous monochloride, stannous tetrachloride pentahydrate, stannous chloride, and stannous chloride dihydrate. More preferably, it includes at least one of stannous acetate, stannous chloride, and stannous chloride dihydrate. Using the above-mentioned preferred tin source helps to reduce the self-polymerization of tin, thereby maintaining the good pore structure of the molecular sieve.

[0030] The polyol can enter the molecular sieve channels together with the tin source. Through interaction with the molecular sieve channels, it effectively isolates tin species and reduces their migration and polymerization to form non-framework species. The polyol can have C2 to C6 carbon atoms and more than 2 hydroxyl groups. Preferably, the ratio of carbon atoms to hydroxyl groups in the polyol is 1 to 1.5. In one specific embodiment, the polyol may include at least one of ethylene glycol, propylene glycol, glycerol, butanediol, pentanediol, hexanediol, butanetetrazol, pentaerythritol, cyclopentanediol, cyclohexanediol, hydroquinone, trioses (such as dihydroxyacetone), tetraoses, pentoses (such as ribose, deoxyribose, ribulose), and hexoses (such as glucose, fructose). Preferably, it includes at least one of ethylene glycol, propylene glycol, glycerol, 1,3-dihydroxyacetone, ribose, glucose, and fructose. More preferably, it includes one or more of ethylene glycol, glycerol, glucose, and fructose. Using the above-mentioned preferred polyols is beneficial for further reducing the formation of non-skeletal tin.

[0031] The solvent can be an inorganic solvent and / or an organic solvent. In one specific embodiment, the solvent includes at least one of water, methanol, ethanol, propanol, and acetone, more preferably water and / or ethanol, and most preferably water.

[0032] The proportions of the components in the liquid mixture can be adjusted within a certain range. Specifically, the molar ratio of tin source (as Sn), polyol, and solvent can be 1:(1~10):(1~10), preferably 1:(2~8):(3~9), and more preferably 1:(3~6):(4~8). The above preferred proportions are more conducive to tin insertion into the molecular sieve framework vacancy.

[0033] The amount of the liquid mixture can be adjusted within a certain range. Specifically, the molar ratio of molecular sieve raw material (calculated as Si) to tin source (or the liquid mixture (calculated as Sn)) can be 1:(0.005~0.10), preferably 1:(0.01~0.06), and more preferably 1:(0.015~0.04).

[0034] The contact can be grinding or impregnation, wherein grinding can achieve better liquid-solid mixing quickly. The contact conditions may include: temperature of 20~100℃, preferably 30~60℃; pressure of -0.01~1MPa (gauge pressure), preferably 0~0.4MPa (gauge pressure); and time of 0.01~24h.

[0035] The product obtained after step S1 can have the solvent removed by means of reduced pressure or increased temperature, or the solvent can be left unremoved, preferably without removing the solvent.

[0036] In step S2, the steam atmosphere used in the steam conditions can be water vapor, organic compound vapor (such as alcohol vapor), or a mixture of organic compound and water vapor, preferably water vapor; the steam can be saturated steam, supersaturated steam, unsaturated steam, or superheated steam. Specifically, the steam conditions may include: a temperature of 100~300℃; a pressure of 0~1.5MPa, preferably 0.1~0.5MPa; and a time of 0.1~5h, preferably 0.5~2h.

[0037] The drying conditions may include: a temperature of 60~200℃ and a time of 0.5~12h; preferably, the drying conditions include: a temperature of 90~150℃ and a time of 1~6h.

[0038] The calcination conditions may include: a temperature of 300~700℃ and a time of 0.5~12h; the calcination may be carried out under oxygen-deficient or oxygen-enriched conditions, and under normal or pressurized conditions; preferably, the calcination conditions include: a temperature of 400~550℃ and a time of 1~6h.

[0039] The synthetic method disclosed herein enables tin to be more effectively inserted into the molecular sieve framework, increasing the framework tin content and thus improving catalytic activity. Simultaneously, it inhibits the formation of non-framework tin, reducing the migration and aggregation of tin species within the molecular sieve channels, preventing channel blockage, and maintaining the good pore structure of the molecular sieve, thereby improving its stability and catalytic selectivity. Furthermore, the synthetic method disclosed herein is simple, uses mild synthesis conditions, and does not require the use of strong acids or fluorinated mineralizers, reducing environmental pollution and equipment corrosion risks, and possesses strong industrial application value.

[0040] A second aspect of this disclosure provides a tin-containing molecular sieve prepared by the method described in the first aspect of this disclosure.

[0041] The tin-containing molecular sieve has a high framework tin content. For tin-containing molecular sieves, tin species with a binding energy near 488.0 eV in the X-ray photoelectron spectroscopy (XPS) spectrum have a four-coordinate structure and are generally considered to be framework tin. Tin species with a binding energy near 487.2 eV have a six-coordinate structure and are generally considered to be non-framework tin. Specifically, in the XPS spectrum of the tin-containing molecular sieve, the 3d... 5 / 2 The signal peak is located at 488.0±0.3eV, and its framework tetracoordinate tin content can be not less than 90% by weight, preferably not less than 96% by weight.

[0042] The tin-containing molecular sieve exhibits excellent catalytic activity and can be widely used in various catalytic reactions, such as esterification, hydrolysis, alcoholysis, transesterification, MPV reaction, aldol condensation, diene addition, Baeyer-Villiger reaction, etc. It is particularly suitable for catalyzing ring-opening reactions of epoxides, which is beneficial for improving the conversion rate of raw materials and the selectivity of target products.

[0043] A third aspect of this disclosure provides the application of the tin-containing molecular sieve described in the second aspect of this disclosure in catalyzing the ring-opening reaction of epoxides.

[0044] The tin-containing molecular sieve can be used in the form of raw powder or in the form of a molded catalyst. The molded catalyst can be spherical, strip-shaped, coated with a molded carrier, etc., and this disclosure is not limited thereto. In the molded catalyst, the content of the tin-containing molecular sieve can be not less than 10% by weight, such as 10% by weight, 15% by weight, 30% by weight, 50% by weight, 70% by weight, 90% by weight, etc. The tin-containing molecular sieve can be used in batch reactors, tubular reactors, fixed-bed reactors, fluidized-bed reactors, moving-bed reactors, microchannel reactors, etc., and this disclosure is also not limited thereto.

[0045] In one specific embodiment, the application includes: using the tin-containing molecular sieve as a catalyst to catalyze the ring-opening reaction of an epoxide with water or an alcohol to generate a diol or an alcohol ether.

[0046] The epoxy compound can be an epoxy compound with C2 to C20 carbon atoms, such as ethylene oxide, propylene oxide, butane oxide, diepoxide, pentane oxide, cyclopentane oxide, hexane oxide, cyclohexane oxide, phenylene oxide, heptane oxide, cycloheptane oxide, octane oxide, nonane oxide, nonane oxide, decane oxide, decane oxide, dicyclopentane-epoxide, dicyclopentane-epoxide, oleic acid, methyl oleate, etc.

[0047] The alcohol can be an alcohol with C1 to C10 carbon atoms, such as methanol, ethanol, propanol, butanol, pentanol, cyclopentanol, hexanol, cyclohexanol, heptanol, cycloheptanol, octanol, cyclooctanol, nonanol, cyclononanol, decanol, cyclodecanol, ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, heptanol, octanediol, nonanediol, decanediol, glycerol, butanediol, pentanetetraethanolamine, etc.

[0048] The molar ratio of the tin-containing molecular sieve (calculated as tin) to the epoxy compound can be (0.001~0.5):1; the molar ratio of the epoxy compound to water or alcohol can be 1:(0.5~20).

[0049] The conditions for the ring-opening reaction may include: a temperature of 20~200℃, a pressure of atmospheric pressure to 5MPa (gauge pressure), and a time of 0.1~24h.

[0050] The present disclosure will be further illustrated by the following examples, but these examples do not limit the scope of the disclosure.

[0051] In the following examples and comparative examples, infrared hydroxyl spectra were obtained using a Thermo Nicolet 750 instrument from Thermo Fisher Scientific, with KBr pellets and a scanning range of 400–4000 cm⁻¹. -1 Chemical composition XRF was measured using a Rigaku 3721E instrument with a tungsten target, an excitation voltage of 40 kV, and an excitation current of 250 mA.

[0052] XPS was performed on a Thermo Fisher Scientific VGESCALAB 250 instrument. The excitation source was monochromatic Al Kα X-rays at an energy of 1486.6 eV and a power of 150 W. A narrow scan with a penetration energy of 30 eV was used. The baseline vacuum during analysis was approximately 6.5 × 10⁻⁶. -8 Pa. The binding energy is corrected using the C1s peak (284.8 eV) of polluting carbon.

[0053] XRD was performed on a Philips Panalytical Empyrean X-ray diffractometer. The test conditions were: Cu target, Kα radiation, Ni filter, tube voltage 40 kV, tube current 40 mA, scintillation counter, step size 0.0131°, and scan range 5° to 35°.

[0054] Unless otherwise specified, all raw materials used are analytical grade reagents.

[0055] In this embodiment, the preparation steps of BEA molecular sieve raw material A with skeletal hydroxyl vacancies are as follows: 50 g (dry basis) of BEA molecular sieve (silicon-to-aluminum atomic ratio of 11.5) was dissolved in water to prepare a molecular sieve solution with a solid content of 10% by weight. 13 mol / L HNO3 was added while stirring, and the solution was heated to 100℃ and stirred for 18 h. The solution was filtered, washed with water until neutral, dried, and calcined at 550℃ for 2 h to obtain BEA molecular sieve A with hydroxyl vacancies in the framework. The BEA molecular sieve A after nitric acid dealumination was subjected to XRD (see...). Figure 1 XRF and FT-IR (see) Figure 2 Analysis and testing. In the FT-IR spectrum, 3550 cm⁻¹ -1 The nearby signal peak can characterize the hydroxyl group, 3735 cm⁻¹ -1 The nearby signal peak can characterize the terminal hydroxyl groups; this molecular sieve has a peak at 3550 cm⁻¹. -1 A characteristic peak is observed nearby, indicating that some framework atoms of the molecular sieve have been removed, leaving skeletal hydroxyl vacancies. The wavenumber is 3735 cm⁻¹. -1 The characteristic peak intensity and wavenumber near 3550 cm⁻¹ -1 The ratio of the intensity of the nearby characteristic peaks I 3735 / I 3550 The silicon-to-aluminum atomic ratio of molecular sieve A is 4.3 after aluminum removal, which is 660.

[0056] In the examples, the preparation steps of STT molecular sieve raw material A' with skeletal hydroxyl vacancies are as follows: The silica-aluminum STT molecular sieve was treated according to the method described in Example 1. The parent molecular sieve had a silica-aluminum atomic ratio of 6:2. After dealumination with nitric acid, its FT-IR spectrum was observed at 3550 cm⁻¹. -1 A characteristic peak is observed nearby, indicating that some framework atoms of the molecular sieve have been removed, leaving skeletal hydroxyl vacancies. The wavenumber is 3735 cm⁻¹. -1 The characteristic peak intensity and wavenumber near 3550 cm⁻¹ -1 The ratio of the intensity of the nearby characteristic peaks I 3735 / I 3550 The silicon-to-aluminum atomic ratio is 4.4. After aluminum removal, the silicon-to-aluminum atomic ratio of molecular sieve A' is 5:10.

[0057] Examples 1-7 illustrate the preparation of tin-containing BEA molecular sieves.

[0058] Example 1 Stannous chloride dihydrate (SnCl2·2H2O), glucose, and water were mixed uniformly at a molar ratio of 1:3:8. Molecular sieve A (based on Si) was then mixed with this liquid mixture (based on Sn) at a molar ratio of 1:0.02. The mixture was ground at 40°C and atmospheric pressure for 1 hour. The product was then transferred to a steam treatment vessel and treated at 150°C and 0.5 MPa steam atmosphere for 1 hour. It was then dried at 120°C for 6 hours and calcined at 500°C in air atmosphere for 6 hours to obtain tin-containing BEA molecular sieve.

[0059] The tin-containing molecular sieve prepared in this embodiment was characterized. The XRF results are shown in Table 1, and the XRD spectra are shown in [Table 1]. Figure 3 XPS spectra can be found Figure 4 This tin-containing molecular sieve has a BEA structure, and the tin species on the surface of the molecular sieve are 3d 5 / 2 The peak is located at 488.0 eV.

[0060] Example 2 Stannous chloride dihydrate, fructose, and water were mixed uniformly in a molar ratio of 1:6:6. Molecular sieve A (based on Si) was then mixed with this liquid mixture (based on Sn) in a molar ratio of 1:0.03. The mixture was ground at 50°C and atmospheric pressure for 2 h. The product was then transferred to a steam treatment vessel and treated at 130°C and 0.3 MPa steam atmosphere for 2 h. It was then dried at 120°C for 6 h and calcined at 500°C in air atmosphere for 6 h to obtain the tin-containing BEA molecular sieve.

[0061] The tin-containing molecular sieve prepared in this embodiment was characterized, and the XRF results are shown in Table 1. The XRD patterns and... Figure 3 Similarly, XPS spectra and Figure 4 Similarly, this tin-containing molecular sieve has a BEA structure, and the tin species on the surface of the molecular sieve are 3d 5 / 2 The peak is located at 488.0 eV.

[0062] Example 3 Stannous acetate (Sn(CH3COO)2), glucose, and ethanol were mixed uniformly at a molar ratio of 1:4:8. Molecular sieve A (based on Si) was then mixed with this liquid mixture (based on Sn) at a molar ratio of 1:0.04. The mixture was ground at 60°C and 0.2 MPa for 0.5 h. The product was then transferred to a steam treatment vessel and treated at 120°C and 0.2 MPa steam atmosphere for 2 h. It was then dried at 120°C for 6 h and calcined at 500°C in air atmosphere for 6 h to obtain the tin-containing BEA molecular sieve.

[0063] The tin-containing molecular sieve prepared in this embodiment was characterized, and the XRF results are shown in Table 1. The XRD patterns and... Figure 3 Similarly, XPS spectra and Figure 4 Similarly, this tin-containing molecular sieve has a BEA structure, and the tin species on the surface of the molecular sieve have 3d... 5 / 2 The peak is located at 488.0 eV.

[0064] Example 4 Stannous chloride (SnCl2), fructose, and ethanol were mixed uniformly at a molar ratio of 1:3:4. Molecular sieve A (based on Si) was then mixed with this liquid mixture (based on Sn) at a molar ratio of 1:0.025. The mixture was ground at 30°C and 0.4 MPa for 6 h. The product was then transferred to a steam treatment vessel and treated at 130°C and 0.3 MPa steam atmosphere for 1 h. It was then dried at 120°C for 6 h and calcined at 500°C in air atmosphere for 6 h to obtain the tin-containing BEA molecular sieve.

[0065] The tin-containing molecular sieve prepared in this embodiment was characterized, and the XRF results are shown in Table 1. The XRD patterns and... Figure 3 Similarly, XPS spectra and Figure 4 Similarly, this tin-containing molecular sieve has a BEA structure, and the tin species on the surface of the molecular sieve have 3d... 5 / 2 The peak is located at 488.0 eV.

[0066] Example 5 Tin tetrachloride pentahydrate (SnCl4·5H2O), 1,3-dihydroxyacetone, and water were mixed uniformly at a molar ratio of 1:1:10. Molecular sieve A (based on Si) was then mixed with this liquid mixture (based on Sn) at a molar ratio of 1:0.06, and impregnated at 20°C and atmospheric pressure for 0.5 h. The product was then transferred to a steam treatment vessel and treated at 100°C and 0.1 MPa steam atmosphere for 0.5 h. It was then dried at 120°C for 6 h and calcined at 500°C in air atmosphere for 6 h to obtain the tin-containing BEA molecular sieve.

[0067] The tin-containing molecular sieve prepared in this embodiment was characterized, and the XRF results are shown in Table 1. The XRD patterns and... Figure 3 Similarly, XPS spectra and Figure 4 Similarly, this tin-containing molecular sieve has a BEA structure, and the tin species on the surface of the molecular sieve have 3d... 5 / 2 The peak is located at 487.8 eV.

[0068] Example 6 Stannous chloride dihydrate, glucose, and water were mixed uniformly at a molar ratio of 1:2:9. Molecular sieve A (based on Si) was then mixed with this liquid mixture (based on Sn) at a molar ratio of 1:0.1, and impregnated at 20°C and atmospheric pressure for 0.5 h. The product was then transferred to a steam treatment vessel and treated at 100°C and 0.1 MPa steam atmosphere for 0.5 h. It was then dried at 120°C for 6 h and calcined at 500°C in air atmosphere for 6 h to obtain tin-containing BEA molecular sieve.

[0069] The tin-containing molecular sieve prepared in this embodiment was characterized, and the XRF results are shown in Table 1. The XRD patterns and... Figure 3 Similarly, XPS spectra and Figure 4 Similarly, this tin-containing molecular sieve has a BEA structure, and the tin species on the surface of the molecular sieve have 3d... 5 / 2 The peak is located at 487.9 eV.

[0070] Example 7 Stannous chloride dihydrate, glucose, and water were mixed uniformly at a molar ratio of 1:10:1. Molecular sieve A (based on Si) was then mixed with this liquid mixture (based on Sn) at a molar ratio of 1:0.005, and impregnated at 20°C and atmospheric pressure for 0.5 h. The product was then transferred to a steam treatment vessel and treated at 100°C and 0.1 MPa steam atmosphere for 0.5 h. It was then dried at 120°C for 6 h and calcined at 500°C in air atmosphere for 6 h to obtain the tin-containing BEA molecular sieve.

[0071] The tin-containing molecular sieve prepared in this embodiment was characterized, and the XRF results are shown in Table 1. The XRD patterns and... Figure 3 Similarly, XPS spectra and Figure 4 Similarly, this tin-containing molecular sieve has a BEA structure, and the tin species on the surface of the molecular sieve have 3d... 5 / 2 The peak is located at 487.7 eV.

[0072] Examples 8 and 9 illustrate the preparation of tin-containing STT molecular sieves.

[0073] Example 8 Stannous chloride dihydrate, glycerol, and water were mixed uniformly at a molar ratio of 1:5:8. Molecular sieve A' (based on Si) was then mixed with this liquid mixture (based on Sn) at a molar ratio of 1:0.015. The mixture was ground at 50°C and atmospheric pressure for 2 hours. The product was then transferred to a steam treatment vessel and treated at 140°C and 0.4 MPa steam atmosphere for 2 hours. It was then dried at 120°C for 6 hours and calcined at 500°C in air atmosphere for 6 hours to obtain the tin-containing STT molecular sieve.

[0074] The tin-containing molecular sieve prepared in this embodiment was characterized. The XRF results are shown in Table 1, and the XRD spectra are shown in [Table 1]. Figure 5 XPS spectra and Figure 4 Similarly, this tin-containing molecular sieve has an STT structure, and the tin species on the surface of the molecular sieve have 3d 5 / 2 The peak is located at 488.0 eV.

[0075] Example 9 Stannous chloride dihydrate, ethylene glycol, and water were mixed uniformly at a molar ratio of 1:4:5. Molecular sieve A' (based on Si) was then mixed with this liquid mixture (based on Sn) at a molar ratio of 1:0.02. The mixture was ground at 60°C and atmospheric pressure for 1 h. The product was then transferred to a steam treatment vessel and treated at 150°C and 0.5 MPa steam atmosphere for 1 h. It was then dried at 120°C for 6 h and calcined at 500°C in air atmosphere for 6 h to obtain the tin-containing STT molecular sieve.

[0076] The tin-containing molecular sieve prepared in this embodiment was characterized, and the XRF results are shown in Table 1. The XRD patterns and... Figure 5 Similarly, XPS spectra and Figure 4 Similarly, this tin-containing molecular sieve has an STT structure, and the tin species on the surface of the molecular sieve have 3d 5 / 2 The peak is located at 488.0 eV.

[0077] Comparative Example 1 Molecular sieve A (based on Si) and tin acetate (based on Sn) were mixed at a molar ratio of 1:0.02 and ground at 40°C and atmospheric pressure for 0.5 h. The product was then calcined at 500°C in air for 6 h to obtain tin-containing BEA molecular sieve.

[0078] The tin-containing molecular sieve prepared in this comparative example was characterized, and the XRF results are shown in Table 1. The XRD patterns and... Figure 3 Similarly, see the XPS spectrum. Figure 6 This tin-containing molecular sieve has a BEA structure, and the tin species on the surface of the molecular sieve are 3d 5 / 2 The peak is located at 487.5 eV.

[0079] Table 1

[0080] As can be seen from Table 1, the tin-containing molecular sieves of the embodiments have a higher content of four-coordinated tin in the surface framework, which can effectively promote tin insertion into the defect sites of the molecular sieve.

[0081] Evaluation example The catalytic performance of tin-containing molecular sieves is evaluated by the ring-opening hydrolysis reaction of epoxides with water or methanol, but this does not limit the use of the tin-containing molecular sieves disclosed herein. The hydrolysis / alcoholization reaction of the epoxides is carried out in a 100 ml flask equipped with an automatically temperature-controlled water bath, magnetic stirring, and reflux condenser.

[0082] The reaction products were analyzed by gas chromatography, and the results were quantified using the internal standard method. The chromatographic conditions were as follows: Agilent-6890 chromatograph, 30m × 0.25mm HP-5 capillary column, injection volume 0.5μL, injection port temperature 280℃. Column temperature was maintained at 50℃ for 5 min, then increased to 280℃ at a rate of 15℃ / min and held for 15 min. An FID detector was used, with a detector temperature of 300℃.

[0083] Epoxy compound conversion rate (%) = (Moles of epoxy compound in feedstock - Moles of epoxy compound in product) / Moles of epoxy compound in feedstock × 100% Diol or alcohol ether selectivity (%) = (moles of diol or alcohol ether in the product) / (moles of epoxide in the feedstock - moles of epoxide in the product) × 100% Evaluation Example 1 The tin-containing molecular sieve, propylene oxide, and water from Example 1 were added to a flask at a ratio of Sn:epoxide (mol) = 0.05:1 and epoxide:water (mol) = 1:5. The reaction was carried out in a water bath at 50°C for 1 hour, then cooled to stop the reaction. The liquid and solid were separated by filtration, and the resulting liquid product was characterized by chromatographic analysis. The analytical results are shown in Table 2.

[0084] Evaluation Example 2 The difference from Evaluation Example 1 is that water is replaced with methanol.

[0085] Evaluation Example 3 The difference from Evaluation Example 1 is that propylene oxide is replaced with ethylene oxide.

[0086] Evaluation Examples 4-12 The difference from Evaluation Example 1 is that the tin-containing molecular sieve of Example 1 was replaced with the tin-containing molecular sieves of Examples 2-8 and Comparative Example 1, respectively.

[0087] Table 2

[0088] As shown in Table 2, the tin-containing molecular sieves prepared using the examples exhibit higher epoxide conversion and product selectivity when used to catalyze the ring-opening reaction of epoxides with water or alcohols to prepare diols or alcohol ethers.

[0089] The preferred embodiments of this disclosure have been described in detail above with reference to the accompanying drawings. However, this disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this disclosure, various simple modifications can be made to the technical solutions of this disclosure, and these simple modifications all fall within the protection scope of this disclosure.

[0090] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.

[0091] Furthermore, various different embodiments of this disclosure can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content disclosed in this disclosure.

Claims

1. A method for preparing a tin-containing molecular sieve, characterized in that, The method includes: The raw material molecular sieve is contacted with a liquid mixture containing a tin source, a polyol, and a solvent to obtain a tin-containing precursor molecular sieve; wherein the raw material molecular sieve has skeletal hydroxyl vacancies. The tin-containing precursor molecular sieve was treated under steam conditions, then dried and calcined to obtain the tin-containing molecular sieve.

2. The method according to claim 1, wherein, The infrared hydroxyl spectrum of the raw material molecular sieve has a wavenumber of 3735 cm⁻¹. -1 The characteristic peak intensity and wavenumber near 3550 cm⁻¹ -1 The ratio of the intensity of the nearby characteristic peaks I 3735 / I 3550 4~10; and / or, The raw material molecular sieve has at least one of the following framework structures: MFI, MEL, BEA, MOR, MWW, STT, and SVR.

3. The method according to claim 1, wherein, The tin source includes at least one of dimethyl tin chloride, tin acetate, stannous acetate, dibutyltin diacetate, alkoxy tin chloride, tin tetrachloride pentahydrate, anhydrous tin tetrachloride, stannous chloride, and stannous chloride dihydrate.

4. The method according to claim 1, wherein, The polyols include at least one of ethylene glycol, propylene glycol, glycerol, butanediol, pentanediol, hexanediol, butanetetrol, pentaerythritol, cyclopentanediol, cyclohexanediol, hydroquinone, trioses, tetraoses, pentoses, and hexoses.

5. The method according to claim 1, wherein, The solvent includes at least one of water, methanol, ethanol, propanol, and acetone.

6. The method according to claim 1, wherein, The molar ratio of the tin source, the polyol, and the solvent is 1:(1~10):(1~10); and / or, The molar ratio of the molecular sieve raw material to the tin source, calculated as Si, is 1:(0.005~0.10).

7. The method according to claim 1, wherein, The contact conditions include: temperature of 20~100℃, pressure of -0.01~1MPa, and time of 0.01~24h.

8. The method according to claim 1, wherein, The steam atmosphere used in the steam conditions is water vapor and / or organic compound vapor, preferably water vapor; Optionally, the steam conditions include: a temperature of 100~300℃, a pressure of 0~1.5MPa, and a time of 0.1~5h.

9. The method according to claim 1, wherein, The drying conditions include: a temperature of 60~200℃ and a time of 0.5~12h; and / or, The roasting conditions include a temperature of 300~700℃ and a time of 0.5~12h.

10. A tin-containing molecular sieve prepared by the method according to any one of claims 1 to 9; Optionally, in the X-ray photoelectron spectroscopy of the tin-containing molecular sieve, the 3d... 5 / 2 The signal peak is located at 488.0±0.3eV, and the framework tetracoordinate tin content of the tin-containing molecular sieve is not less than 90% by weight.

11. The application of the tin-containing molecular sieve according to claim 10 in catalyzing the ring-opening reaction of epoxides; Optionally, the application includes: Using the tin-containing molecular sieve as a catalyst, an epoxy compound is catalyzed to undergo a ring-opening reaction with water or an alcohol.

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