Silica-alumina type MCM-47 molecular sieve, its preparation method and application

Abstract

This invention relates to the field of catalytic material synthesis, and discloses a silica-alumina type MCM-47 molecular sieve, its preparation method, and its applications. The MCM-47 molecular sieve is a silica-alumina type molecular sieve, using silica-alumina gel as a composite silica-alumina source. The aluminum in the synthesized silica-alumina type MCM-47 molecular sieve exists in a four-coordinate form in the molecular sieve framework and has acid centers, solving the problem that existing technologies cannot synthesize MCM-47 molecular sieves with aluminum-containing frameworks.

Description

Technical Field

[0001] This invention relates to the field of catalytic material synthesis, and more specifically, to a silica-alumina type MCM-47 molecular sieve, its preparation method, and its application. Background Technology

[0002] Molecular sieves are an important class of crystalline microporous materials. Due to their unique and regular pore structure, they are widely used in various fields such as ion exchange, adsorption separation, and catalysis. Based on their framework elemental composition, molecular sieves can be classified into pure silicon molecular sieves, silicon-aluminum molecular sieves, phosphorus-aluminum molecular sieves, silicon-phosphorus-aluminum molecular sieves, and metal heteroatom molecular sieves.

[0003] MCM-47 molecular sieve was first synthesized by Mobil Corporation in 1991 (US5068096). Using 1,4-bis(N-methylpyrrolidine)butane bromide (1,4-MPB) as a template agent, a mixture of silicon source, NaOH, template agent, and water is crystallized at 160°C for 3-7 days to synthesize MCM-47 molecular sieve. This method can only synthesize pure silicon MCM-47 molecular sieve; it cannot allow Al to enter the molecular sieve framework, making it difficult to synthesize silica-alumina type MCM-47 molecular sieves.

[0004] A novel method for synthesizing MCM-47 molecular sieves using a template agent (Studies in Surface Science and Catalysis. 2005, 158: 183-190.) is reported. Using 1,4-bis(methyldiethyl)butane bromide as the template agent, silica as the silicon source, and NaOH or KOH as the inorganic base source, the initial gel is prepared according to a molar ratio of 4.5R:5Na₂O:30SiO₂:1200H₂O. Crystallization at 160℃ for 7 days yields MCM-47 molecular sieves. Similarly, the synthesis phase region of MCM-47 molecular sieves using 1,4-bis(methyldiethyl)butane bromide as the template agent is very narrow, easily leading to the formation of amorphous substances, dense phases, or other molecular sieves. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a silicon-aluminum type MCM-47 molecular sieve, its preparation method and application. It is synthesized using silicon-aluminum gel as a composite silicon-aluminum source. The aluminum in the silicon-aluminum type MCM-47 molecular sieve exists in a four-coordinate form in the molecular sieve framework. The MCM-47 molecular sieve has acid centers, which solves the problem that the prior art cannot synthesize MCM-47 molecular sieves with aluminum-containing framework.

[0006] To address the aforementioned technical problems, this invention provides a method for preparing a silica-alumina type MCM-47 molecular sieve, comprising: crystallizing a mixture containing silica-alumina gel, inorganic alkali, template agent, and water, wherein the molar ratio of SiO2 to Al2O3 in the silica-alumina gel is less than or equal to 120.

[0007] The present invention also provides a silicon-aluminum type MCM-47 molecular sieve, which is prepared by the above method, or the molar ratio of SiO2 to Al2O3 in the silicon-aluminum type MCM-47 molecular sieve is 200-430, aluminum exists in the molecular sieve framework in a four-coordinated form, and has acid centers.

[0008] This invention also relates to the use of aluminosilicate gel and / or the compound shown in Formula I in the preparation of aluminosilicate MCM-47 molecular sieves.

[0009] Through the above technical solutions, this invention obtains a silica-alumina type MCM-47 molecular sieve in which aluminum exists in a four-coordinated form within the molecular sieve framework, and this molecular sieve has acid centers with a SiO2 / Al2O3 ratio of 200-430. Furthermore, the preparation method of this invention is simple to operate and highly practical. Attached Figure Description

[0010] Figure 1 The XRD pattern of the molecular sieve raw powder synthesized in Example 1 is shown below.

[0011] Figure 2 The XRD pattern of the molecular sieve raw powder synthesized in Example 2 is shown below.

[0012] Figure 3 The XRD pattern of the molecular sieve raw powder synthesized in Example 3 is shown below.

[0013] Figure 4 The XRD pattern of the molecular sieve raw powder synthesized in Example 4 is shown below.

[0014] Figure 5 Here is a SEM image of the molecular sieve raw powder synthesized in Example 4;

[0015] Figure 6 The XRD pattern of the hydrogen-form molecular sieve synthesized in Example 4;

[0016] Figure 7 The XRD pattern of the molecular sieve raw powder synthesized in Example 7 is shown below.

[0017] Figure 8 SEM image of the molecular sieve raw powder synthesized in Example 7;

[0018] Figure 9 The XRD pattern of the hydrogen-form molecular sieve synthesized in Example 7;

[0019] Figure 10 The hydrogen-form molecular sieve synthesized in Example 7 27 Al NMR spectrum;

[0020] Figure 11 The XRD pattern of the molecular sieve raw powder synthesized in Example 8;

[0021] Figure 12 The XRD pattern of the molecular sieve raw powder synthesized in Example 9;

[0022] Figure 13 The XRD pattern of the molecular sieve raw powder synthesized in Example 10;

[0023] Figure 14 The XRD pattern of the molecular sieve raw powder synthesized in Example 11 is shown below.

[0024] Figure 15 The image shows the XRD pattern of the molecular sieve sample synthesized in Comparative Example 1. Detailed Implementation

[0025] The endpoints and any values ​​of the ranges 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 endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0026] In this invention, technical terms that are given a definition shall be used as defined thereon, while those not given a definition shall be understood according to their common meaning in the art. The template agent in this invention is also referred to in the art as a structure-directing agent or an organic structure-directing agent. "Silica-alumina type MCM-47 molecular sieve" refers to an MCM-47 molecular sieve in which Al exists within the molecular sieve framework.

[0027] The method for preparing silica-alumina type MCM-47 molecular sieve provided by the present invention includes: crystallizing a mixture containing silica-alumina gel, inorganic alkali, template agent and water, wherein the molar ratio of SiO2 to Al2O3 in the silica-alumina gel is less than or equal to 120, preferably 50-100 (such as 55, 58, 70, 78, 80, 90, 95, 96, 98 or any value between the above values).

[0028] In this invention, relative to each mole of SiO2-based aluminosilicate gel, OH... - The amount of inorganic base used is preferably 0.3-0.5 mol (e.g., 0.32, 0.35, 0.38, 0.4, 0.44, 0.46, 0.48 mol or any value between the above).

[0029] In this invention, the amount of template agent used is preferably 0.1-0.2 mol (e.g., 0.11, 0.14, 0.16, 0.17, 0.2 mol or any value between the above values) relative to each mole of SiO2-based silica-alumina paste.

[0030] In this invention, the amount of water used is preferably 15-50 mol (e.g., 15, 18, 22, 30, 35, 38, 42, 44, 46, 48 mol or any value between the above values) relative to each mole of SiO2-based silica-alumina gel.

[0031] According to the present invention, crystallization according to the relative amounts described in the preferred embodiments above can yield pure phase MCM-47 molecular sieves, and no other molecular sieves are present in the crystallization product.

[0032] In this invention, there are no special requirements for the selection of the inorganic base, which can be a common inorganic base in the art. Preferably, the inorganic base is selected from alkali metal hydroxides and / or alkaline earth metal hydroxides, and more preferably sodium hydroxide.

[0033] In a preferred embodiment of the present invention, the template agent is selected from at least one of the compounds shown in Formula I:

[0034]

[0035] In Formula I, X is selected from halogens (such as Cl, Br), and n = 4.

[0036] In a more preferred embodiment, the template agent is selected from 1,4-bis(N-methylpyrrolidine)butane bromide (i.e., X is Br) and / or 1,4-bis(N-methylpyrrolidine)butane chloride (i.e., X is Cl).

[0037] In this invention, there are no particular requirements for the crystallization method; a single-stage crystallization or a two-stage crystallization can be used. In a preferred embodiment of this invention, the crystallization includes sequentially performing a first-stage crystallization and a second-stage crystallization. More preferably, the temperature of the first-stage crystallization is 25-55°C lower than the temperature of the second-stage crystallization (e.g., 26, 28, 32, 35, 38, 42, 45, 48, 52, 54°C or any value between these values). More preferably, the time for the first-stage crystallization is 3-5 days shorter than the time for the second-stage crystallization (e.g., 3.2, 3.5, 3.8, 4.2, 4.5, 4.8 days or any value between these values).

[0038] More preferably, the conditions for the first stage of crystallization include: a temperature of 110-130℃ (such as 111, 112, 115, 118, 122, 128, 129℃ or any value between the above values). More preferably, the conditions for the first stage of crystallization also include: a time of 0.5-1.5 days (such as 0.6, 0.8, 0.9, 1.1, 1.2, 1.3, 1.4 days or any value between the above values).

[0039] More preferably, the conditions for the second stage of crystallization include: a temperature of 150-170℃ (such as 151, 152, 155, 158, 162, 168, 169℃ or any value between the above). More preferably, the conditions for the second stage of crystallization also include: a time of 4-6 days (such as 4.2, 4.5, 4.8, 5.2, 5.5, 5.8 days or any value between the above).

[0040] In this invention, crystallization under the crystallization conditions described in the preferred embodiments above can yield pure-phase MCM-47 molecular sieves, and no other molecular sieves are present in the crystallization product.

[0041] In this invention, the crystallization process does not have specific pressure requirements and can be performed under self-generated pressure. The crystallization can be static or dynamic, with dynamic crystallization being preferred. As a condition for dynamic crystallization, a rotational speed of 15-40 r / min is preferred.

[0042] In this invention, to obtain hydrogen-form molecular sieves, the method may further include solid-liquid separation of the crystallized product, followed by sequential washing, drying, ion exchange, and calcination of the obtained solid phase to obtain the hydrogen-form molecular sieve. Specifically, the solid-liquid separation method can be performed using conventional methods, such as filtration and centrifugation. Furthermore, the solid phase obtained from the solid-liquid separation is washed before drying. The washing can be performed using conventional methods; to avoid introducing other impurities, it is preferable to wash with deionized water until neutral. The drying can be carried out at a temperature of 80-120°C, and the drying time can be selected according to the drying temperature, generally 4-15 hours. Ion exchange transforms the crystallized product (molecular sieve) from the sodium form to the ammonium form. There are no special requirements for the ion exchange method; for example, the crystallized product (molecular sieve), ammonium salt (such as ammonium chloride), and water can be mixed at a weight ratio of 1:0.2-0.5:15-30 and heated to 60-80°C while stirring for 1.5-5 hours. The calcination process transforms the molecular sieve from the ammonium form to the hydrogen form. There are no special requirements for the calcination, and the hydrogen-form silica-alumina type MCM-47 molecular sieve is obtained after calcination. The calcination conditions may include: air atmosphere, temperature of 500-600℃, and time of 3-5 hours.

[0043] This invention also provides a silica-alumina type MCM-47 molecular sieve, characterized in that the silica-alumina type MCM-47 molecular sieve is prepared by the method described above; or, the molar ratio of SiO2 to Al2O3 in the silica-alumina type MCM-47 molecular sieve is 200-430, aluminum exists in a four-coordinate form in the molecular sieve framework, and it has acid centers. Preferably, the amount of Brønsted acid generated from the framework Si-OH-Al in the silica-alumina type MCM-47 molecular sieve is 10-45 μmol Py·g. -1 .

[0044] This invention also relates to the use of aluminosilicate gel and / or the compound shown in Formula I in the preparation of aluminosilicate MCM-47 molecular sieves.

[0045] The present invention will be described in detail below through embodiments. In the following embodiments and comparative examples,

[0046] X-ray powder diffraction (XRD) phase analysis was performed using a Panaco Empyrean diffractometer from the Netherlands, equipped with a PIXcel... 3D Detector. Test conditions: Cu target, Kα radiation, Ni filter, tube voltage 40kV, tube current 40mA, scan range 5°-50°.

[0047] Scanning electron microscopy (SEM) morphology analysis was performed using a Hitachi S4800 SEM. Test conditions: After drying and grinding, the samples were adhered to conductive adhesive. The accelerating voltage of the analytical electron microscope was 5.0 kV, and the magnification ranged from 20 to 800,000 times.

[0048] 27 The instrument used for Al MAS NMR analysis was a Bruker Avance III 600MHz nuclear magnetic resonance spectrometer. Test conditions: 4mm WVT dual resonance probe; resonance frequency 156.39MHz; sampling time 6.55ms; delay time 1s; pulse width 0.4μs; 6000 samples; rotation speed 12000Hz.

[0049] The testing instrument for X-ray fluorescence analysis (XRF analysis) was a Philips MagiX fluorescence spectrometer. Testing conditions included a tungsten target, excitation voltage of 40 kV, and excitation current of 50 mA. The intensity of characteristic spectral lines for each element was determined using a scintillation calculator and a proportionality calculator for semi-quantitative elemental analysis.

[0050] The acid type was determined using pyridine infrared adsorption spectroscopy (Py-IR) with a Thermo Nicolet 750 Fourier transform infrared spectrometer. Test conditions: 1400–1700 cm⁻¹ -1The wavenumber range was scanned, the infrared absorption spectrum at 200℃ was recorded, and the acidity of Brønsted acid and Lewis acid was calculated.

[0051] R represents the template agent 1,4-bis(N-methylpyrrolidine)butane bromide (1,4-MPB).

[0052] Silicon-aluminum adhesives with different silicon-to-aluminum ratios (SiO2 / Al2O3 molar ratio of 50-100) were purchased from Dongying Yiming New Materials Co., Ltd.

[0053] Examples 1-7 illustrate the synthesis of silica-alumina type MCM-47 molecular sieves according to the method of the present invention.

[0054] Example 1

[0055] Add 20.355 g of deionized water to the polytetrafluoroethylene liner, then add 1,4-bis(N-methylpyrrolidine)butane bromide (1,4-MPB) and NaOH in sequence, stirring until homogeneous. Then add aluminosilicate gel (solid content 95 wt%, SiO2 mass fraction 97.22%, Al2O3 mass fraction 2.75%, SiO2 / Al2O3 = 60), and stir until homogeneous. The molar ratios of the components are: NaOH / SiO2 = 0.45, R / SiO2 = 0.15, H2O / SiO2 = 20.

[0056] The polytetrafluoroethylene liner containing the above reaction mixture was covered, placed in a stainless steel autoclave and sealed, and then placed in a rotating convection oven at a speed of 20 r / min for crystallization under autogenous pressure: first crystallized at 120℃ for 1 day, then at 160℃ for 5 days. After crystallization was completed, the product was removed by cooling to room temperature, filtered, washed, and dried at 110℃ for 12 hours to obtain molecular sieve powder.

[0057] The obtained molecular sieve powder was subjected to X-ray diffraction analysis. The XRD pattern is shown in the figure. Figure 1 The XRD patterns of the MCM-47 molecular sieve raw powder synthesized in the literature (Chem. Mater. 2000, 12, 2936-2942.) are compared with those of the raw powder. Figure 1 The results confirmed that it was a pure-phase MCM-47 molecular sieve.

[0058] Molecular sieve powder was subjected to ammonium ionization treatment. Molecular sieve, ammonium chloride, and deionized water were mixed at a mass ratio of 1:0.3:20, heated to 70℃ and stirred for 2 hours. After washing, filtering, and drying, the ammonium-form molecular sieve was obtained. Calcination at 550℃ for 4 hours yielded the hydrogen-form molecular sieve. 27 Al NMR was used to analyze the molecular sieve. 27The Al NMR spectrum showed a chemical shift of 56 ppm for Al, indicating that aluminum exists in a four-coordinated form within the molecular sieve framework. XRF analysis of the molecular sieve revealed a SiO2 / Al2O3 molar ratio of 233.7. Py-IR analysis of the molecular sieve showed an acidity of 39 μmol Py·g⁻¹, derived from the framework Si-OH-Al acid. -1 .

[0059] Example 2

[0060] Referring to Example 1, only the amount of NaOH added was changed to NaOH / SiO2 = 0.4, and the crystallization conditions were changed to: first crystallize at 120℃ for 1 day, and then crystallize at 160℃ for 4 days.

[0061] The obtained molecular sieve powder was subjected to X-ray diffraction analysis. The XRD pattern is shown in the figure. Figure 2 It was confirmed to be a pure-phase MCM-47 molecular sieve.

[0062] Molecular sieve powder was subjected to ammonium ionization treatment. Molecular sieve, ammonium chloride, and deionized water were mixed at a mass ratio of 1:0.3:20, heated to 70℃ and stirred for 2 hours. After washing, filtering, and drying, the ammonium-form molecular sieve was obtained. Calcination at 550℃ for 4 hours yielded the hydrogen-form molecular sieve. 27 Al NMR was used to analyze the molecular sieve. 27 The Al NMR spectrum showed a chemical shift of 56 ppm for Al, indicating that aluminum exists in a four-coordinated form within the molecular sieve framework. XRF analysis of the molecular sieve revealed a SiO2 / Al2O3 molar ratio of 241.2. Py-IR analysis of the molecular sieve showed an acidity of 37 μmol Py·g⁻¹, derived from the framework Si-OH-Al acid. -1 .

[0063] Example 3

[0064] Referring to Example 1, only the amount of NaOH added was changed to NaOH / SiO2 = 0.36, and the crystallization conditions were changed to: first crystallize at 120℃ for 1 day, and then crystallize at 160℃ for 6 days.

[0065] The obtained molecular sieve powder was subjected to X-ray diffraction analysis. The XRD pattern is shown in the figure. Figure 3 It was confirmed to be a pure-phase MCM-47 molecular sieve.

[0066] Molecular sieve powder was subjected to ammonium ionization treatment. Molecular sieve, ammonium chloride, and deionized water were mixed at a mass ratio of 1:0.3:20, heated to 70℃ and stirred for 2 hours. After washing, filtering, and drying, the ammonium-form molecular sieve was obtained. Calcination at 550℃ for 4 hours yielded the hydrogen-form molecular sieve. 27 Al NMR was used to analyze the molecular sieve. 27The Al NMR spectrum showed a chemical shift of 56 ppm, indicating that aluminum exists in a four-coordinated form within the molecular sieve framework. XRF analysis of the molecular sieve revealed a SiO2 / Al2O3 molar ratio of 228.9. Py-IR analysis of the molecular sieve showed an acidity of 39 μmol Py·g⁻¹, indicating the presence of Brønsted acid (B acid) generated from the framework Si-OH-Al. -1 .

[0067] Example 4

[0068] Add 14.932 g of deionized water to the polytetrafluoroethylene liner, then add 1,4-bis(N-methylpyrrolidine)butane bromide (1,4-MPB) (69% by mass) and NaOH (96% by mass) in sequence, and stir until homogeneous. Then add aluminosilicate gel (93.7% by weight solid content, 97.59% by mass SiO2, 2.09% by mass Al2O3, SiO2 / Al2O3 = 79.24), and stir until homogeneous. The molar ratios of the components are: NaOH / SiO2 = 0.45, R / SiO2 = 0.12, and H2O / SiO2 = 15.

[0069] The polytetrafluoroethylene liner containing the above reaction mixture was covered, placed in a stainless steel autoclave and sealed, and then placed in a rotating convection oven at a speed of 20 r / min for crystallization under autogenous pressure: first crystallized at 120℃ for 1 day, then at 150℃ for 6 days. After crystallization was completed, the product was removed by cooling to room temperature, filtered, washed, and dried at 110℃ for 12 hours to obtain molecular sieve powder.

[0070] The obtained molecular sieve powder was subjected to X-ray diffraction analysis. The XRD pattern is shown in the figure. Figure 4 It was confirmed to be a pure-phase MCM-47 molecular sieve. The morphology of the molecular sieve was observed using SEM; the SEM images are shown below. Figure 5 It has a plate-like prismatic shape.

[0071] Molecular sieve powder was subjected to ammonium ionization treatment. Molecular sieve, ammonium chloride, and deionized water were mixed at a mass ratio of 1:0.3:20, heated to 70℃ and stirred for 2 hours. The mixture was then washed, filtered, and dried to obtain the ammonium-type molecular sieve. Calcination at 550℃ for 4 hours yielded the hydrogen-type molecular sieve.

[0072] The obtained hydrogen-form molecular sieve was subjected to X-ray diffraction analysis; the XRD pattern is shown below. Figure 6 The XRD spectra of the calcined MCM-47 molecular sieve samples synthesized in the literature (Chem. Mater. 2000, 12, 2936-2942.) are compared with those of the samples synthesized in the literature (Chem. Mater. 2000, 12, 2936-2942.). Figure 1 Confirmed to be a pure-phase hydrogen-form MCM-47 molecular sieve. (Using...) 27 Al NMR was used to analyze the molecular sieve. 27The Al NMR spectrum showed a chemical shift of 56 ppm for Al, indicating that aluminum exists in a four-coordinated form within the molecular sieve framework. XRF analysis of the molecular sieve revealed a SiO2 / Al2O3 molar ratio of 324.7. Py-IR analysis of the molecular sieve showed an acidity of 24 μmol Py·g⁻¹, derived from the framework Si-OH-Al acid. -1 .

[0073] Example 5

[0074] Add 42.837 g of deionized water to the polytetrafluoroethylene liner, then add 1,4-bis(N-methylpyrrolidine)butane bromide (1,4-MPB) (69% by mass) and NaOH (96% by mass) in sequence, and stir until homogeneous. Then add aluminosilicate gel (95.60% solid content, 98.03% SiO2 by mass, 1.74% Al2O3 by mass, SiO2 / Al2O3 = 95.61), and stir until homogeneous. The molar ratios of the components are: NaOH / SiO2 = 0.45, R / SiO2 = 0.18, and H2O / SiO2 = 40.

[0075] The polytetrafluoroethylene liner containing the above reaction mixture was covered, placed in a stainless steel autoclave and sealed, and then placed in a rotating convection oven at a speed of 20 r / min for crystallization under autogenous pressure: first crystallized at 110℃ for 1 day, then at 160℃ for 4 days. After crystallization was completed, the product was removed by cooling to room temperature, filtered, washed, and dried at 110℃ for 12 hours to obtain molecular sieve powder.

[0076] The obtained molecular sieve raw powder was subjected to X-ray diffraction analysis and the morphology of the molecular sieve was observed by SEM. The characterization results showed that the sample was a pure phase MCM-47 molecular sieve and the sample morphology was a plate-prism morphology.

[0077] Molecular sieve powder was subjected to ammonium ionization treatment. Molecular sieve, ammonium chloride, and deionized water were mixed at a mass ratio of 1:0.3:20, heated to 70℃ and stirred for 2 hours. After washing, filtering, and drying, the ammonium-form molecular sieve was obtained. Calcination at 550℃ for 4 hours yielded the hydrogen-form molecular sieve. 27 Al NMR was used to analyze the molecular sieve. 27 The Al NMR spectrum showed a chemical shift of 56 ppm for Al, indicating that aluminum exists in a four-coordinated form within the molecular sieve framework. XRF analysis of the molecular sieve revealed a SiO2 / Al2O3 molar ratio of 419.3. Py-IR analysis of the molecular sieve showed an acidity of 12 μmol Py·g⁻¹, indicating the presence of Brønsted acid (B acid) generated from the framework Si-OH-Al. -1 .

[0078] Example 6

[0079] Add 47.095 g of deionized water to the polytetrafluoroethylene liner, then add 1,4-bis(N-methylpyrrolidine)butane bromide (1,4-MPB) (69% by mass) and NaOH (96% by mass) in sequence and stir until homogeneous. Then add aluminosilicate gel (93.70% solid content, 97.59% SiO2 by mass, 2.09% Al2O3 by mass, SiO2 / Al2O3 = 79.24) and stir until homogeneous. The molar ratios of the components are: NaOH / SiO2 = 0.4, R / SiO2 = 0.19, and H2O / SiO2 = 45.

[0080] The polytetrafluoroethylene liner containing the above reaction mixture was covered, placed in a stainless steel autoclave and sealed, and then placed in a rotating convection oven at a speed of 20 r / min for crystallization under autogenous pressure: first crystallized at 130℃ for 1 day, then at 160℃ for 4 days. After crystallization was completed, the product was removed by cooling to room temperature, filtered, washed, and dried at 110℃ for 12 hours to obtain molecular sieve powder.

[0081] The obtained molecular sieve raw powder was subjected to X-ray diffraction analysis and the morphology of the molecular sieve was observed by SEM. The characterization results showed that the sample was a pure phase MCM-47 molecular sieve and the sample morphology was a plate-prism morphology.

[0082] Molecular sieve powder was subjected to ammonium ionization treatment. Molecular sieve, ammonium chloride, and deionized water were mixed at a mass ratio of 1:0.3:20, heated to 70℃ and stirred for 2 hours. After washing, filtering, and drying, the ammonium-form molecular sieve was obtained. Calcination at 550℃ for 4 hours yielded the hydrogen-form molecular sieve. 27 Al NMR was used to analyze the molecular sieve. 27 The Al NMR spectrum showed a chemical shift of 56 ppm for Al, indicating that aluminum exists in a four-coordinated form within the molecular sieve framework. XRF analysis of the molecular sieve revealed a SiO2 / Al2O3 molar ratio of 299.5. Py-IR analysis of the molecular sieve showed an acidity of 29 μmol Py·g⁻¹, derived from the framework Si-OH-Al acid. -1 .

[0083] Example 7

[0084] Add 20.897 g of deionized water to the polytetrafluoroethylene liner, then add 1,4-bis(N-methylpyrrolidine)butane bromide (1,4-MPB) (69% by mass) and NaOH (96% by mass) in sequence, and stir until homogeneous. Then add aluminosilicate gel (95.60% solid content, 98.03% SiO2 by mass, 1.74% Al2O3 by mass, SiO2 / Al2O3 = 95.61), and stir until homogeneous. The molar ratios of the components are: NaOH / SiO2 = 0.45, R / SiO2 = 0.13, and H2O / SiO2 = 20.

[0085] The polytetrafluoroethylene liner containing the above reaction mixture was covered, placed in a stainless steel autoclave and sealed, and then placed in a rotating convection oven at a speed of 20 r / min for crystallization under autogenous pressure: first crystallized at 120℃ for 1 day, then at 170℃ for 5 days. After crystallization was completed, the product was removed by cooling to room temperature, filtered, washed, and dried at 110℃ for 12 hours to obtain molecular sieve powder.

[0086] The obtained molecular sieve powder was subjected to X-ray diffraction analysis. The XRD pattern is shown in the figure. Figure 7 It was confirmed to be a pure-phase MCM-47 molecular sieve. The morphology of the molecular sieve was observed using SEM; the SEM images are shown below. Figure 8 It has a plate-like prismatic shape.

[0087] The molecular sieve powder was subjected to ammonium exchange treatment. The molecular sieve, ammonium chloride, and deionized water were mixed at a mass ratio of 1:0.3:20, heated to 70℃ and stirred for 2 hours. After washing, filtering, and drying, the ammonium-type molecular sieve was obtained. The hydrogen-type molecular sieve was obtained by calcination at 550℃ for 4 hours.

[0088] The obtained hydrogen-form molecular sieve was subjected to X-ray diffraction analysis; the XRD pattern is shown below. Figure 9 It was confirmed to be a pure-phase MCM-47 molecular sieve. Using... 27 Al NMR was used to analyze the molecular sieve. 27 The Al NMR spectrum is shown below. Figure 10 The chemical shift of Al was 56 ppm, indicating that aluminum exists in the molecular sieve framework in a tetracoordinate form. XRF analysis of the molecular sieve revealed a SiO2 / Al2O3 molar ratio of 427.8. Py-IR analysis of the molecular sieve showed that the amount of Brønsted acid (B acid) generated from the framework Si-OH-Al was 11 μmol Py·g. -1 .

[0089] Example 8

[0090] According to Example 1, the difference is that the crystallization conditions are: first crystallize at 120°C for 1 day, then crystallize at 160°C for 8 days.

[0091] The obtained solid was subjected to X-ray diffraction analysis, and the XRD pattern is shown in the figure. Figure 11 It was confirmed that it was a miscible phase of other molecular sieves and MCM-47, and pure phase MCM-47 molecular sieve could not be synthesized.

[0092] Example 9

[0093] According to Example 2, the difference is that the crystallization conditions are: first crystallize at 120°C for 1 day, then crystallize at 160°C for 10 days.

[0094] The obtained solid was subjected to X-ray diffraction analysis, and the XRD pattern is shown in the figure. Figure 12 It was confirmed that it was a miscible phase of other molecular sieves and MCM-47, and pure phase MCM-47 molecular sieve could not be synthesized.

[0095] Example 10

[0096] According to Example 2, the difference is that R / SiO2 = 0.3.

[0097] The obtained solid was subjected to X-ray diffraction analysis, and the XRD pattern is shown in the figure. Figure 13 It was confirmed that it was a miscible phase of other molecular sieves and MCM-47, and pure phase MCM-47 molecular sieve could not be synthesized.

[0098] Example 11

[0099] According to Example 1, the difference is that NaOH / SiO2 = 0.6.

[0100] The obtained solid was subjected to X-ray diffraction analysis, and the XRD pattern is shown in the figure. Figure 14 It was confirmed that it was a mixed phase of other molecular sieves, α-quartz and MCM-47, and pure phase MCM-47 molecular sieve could not be synthesized.

[0101] Comparative Example 1

[0102] According to Example 7, the difference is that coarse-porous silica gel (solid content 92.5% by weight) was used as the silicon source, and sodium aluminate (specific gravity 1.206 g / ml, Al2O3 mass concentration 101.5 g / L, NaOH mass fraction 194.0 g / L) was used as the aluminum source.

[0103] The obtained solid was subjected to X-ray diffraction analysis, and the XRD pattern is shown in the figure. Figure 15 It was confirmed that the substance was amorphous and could not be used to synthesize pure-phase MCM-47 molecular sieves. Therefore, it can be concluded that, under the same ratio and crystallization conditions, MCM-47 molecular sieves cannot be synthesized using only silicon and aluminum sources.

[0104] As can be seen from Example 7 and Comparative Example 1, MCM-47 molecular sieves can only be obtained by using silica-alumina gel as the silica-alumina source. Comparing Examples 1-7 with Examples 8-11, it can be seen that pure-phase MCM-47 molecular sieves can be obtained by controlling the crystallization conditions or the relative amounts of raw materials within the preferred range, and no other molecular sieves are present in the crystallization product.

[0105] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for preparing silica-alumina type MCM-47 molecular sieve, characterized in that, The method includes: crystallizing a mixture containing aluminosilicate gel, inorganic alkali, template agent and water, wherein the molar ratio of SiO2 to Al2O3 in the aluminosilicate gel is less than or equal to 120; The template agent is selected from at least one of the compounds shown in Formula I: Formula I In Formula I, X is selected from halogens, and n=4; Relative to each mole of silica-alumina paste calculated as SiO2, expressed as OH - The amount of inorganic base used is 0.3-0.5 mol, the amount of template agent is 0.1-0.2 mol, and the amount of water is 15-50 mol. The crystallization process includes sequentially performing a first-stage crystallization and a second-stage crystallization. The conditions for the first stage of crystallization include: a temperature of 110-130℃ and a time of 0.5-1.5 days; The conditions for the second stage of crystallization include: a temperature of 150-170℃ and a time of 4-6 days.

2. The method according to claim 1, wherein, The molar ratio of SiO2 to Al2O3 in the silica-alumina adhesive is 50-100.

3. The method according to claim 1, wherein, The inorganic base is selected from alkali metal hydroxides and / or alkaline earth metal hydroxides.

4. The method according to claim 3, wherein, The inorganic base is selected from sodium hydroxide.

5. The method according to claim 1, wherein, The template agent is selected from 1,4-bis(N-methylpyrrolidine)butane bromide and / or 1,4-bis(N-methylpyrrolidine)butane chloride.

6. The method according to any one of claims 1-3, wherein, The method further includes solid-liquid separation of the crystallized product, followed by washing, drying, ion exchange and calcination of the obtained solid phase to obtain hydrogen-type molecular sieves.

7. The method according to claim 6, wherein, The roasting conditions include: an air atmosphere, a temperature of 500-600℃, and a time of 3-5 hours.

8. A silica-alumina type MCM-47 molecular sieve, characterized in that, The silica-aluminate type MCM-47 molecular sieve is prepared by the method described in any one of claims 1-7.

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