Tungsten-containing hierarchical pore ZSM-5 zeolite molecular sieve and preparation method thereof

Abstract

The preparation method comprises the following steps: mixing a silicon source, an aluminum source, a tungsten source, an additive, a seed crystal, sodium oxide and water to form a reaction system, and sequentially crystallizing and roasting the reaction system to obtain the tungsten-containing hierarchical pore ZSM-5 zeolite molecular sieve, according to the method, the tungsten-containing hierarchical pore ZSM-5 zeolite molecular sieve can be directly synthesized by adopting a one-step hydrothermal method under the condition that a second template agent is not added.

Description

Technical Field

[0001] This invention belongs to the field of zeolite molecular sieve synthesis technology, and relates to a tungsten-containing hierarchical porous ZSM-5 zeolite molecular sieve and its preparation method. Background Technology

[0002] Zeolite molecular sieves are crystalline inorganic aluminosilicate framework materials, characterized by uniformly sized micropores and neatly arranged cavities in their crystal structure. ZSM-5 zeolite molecular sieves, due to their unique pore structure, good thermal stability, suitable and tunable acid center density, and excellent shape-selective catalysis, are widely used as solid acid catalysts in petrochemical, coal chemical, and other fields. Simultaneously, ZSM-5 zeolite molecular sieves are excellent supports for catalytically active metal ions or metal oxides. Iron, tungsten, and manganese catalysts supported on ZSM-5 zeolite molecular sieves exhibit excellent catalytic performance in olefin catalytic cracking and hydrocarbon aromatization reactions. CN202411461118.4 provides a zinc-modified hierarchical three-dimensional nanosheet ZSM-5 molecular sieve catalyst, which exhibits higher n-octane aromatization performance while inhibiting further aromatization on the catalyst surface. The n-octane conversion rate reaches over 99%, and the BTX selectivity reaches 71%.

[0003] ZSM-5 zeolite molecular sieves are mesoporous materials with 10-membered ring channels. Due to their small channel size, the diffusion of reactants is restricted, which reduces the efficiency of catalytic reactions to some extent. Furthermore, adjusting the acidity of ZSM-5 zeolite molecular sieves often requires the loading of one or more metals, and the loading method is affected by the utilization rate of the metal loading and the complexity of the process.

[0004] To address the diffusion limitation caused by the small pore size of ZSM-5 zeolite molecular sieves, hierarchical porous structures are typically introduced into the zeolite molecular sieve system, combining the mass transport properties of mesoporous zeolite molecular sieves with the catalytic characteristics of microporous zeolite molecular sieves. Currently, the main methods for synthesizing hierarchical ZSM-5 zeolite molecular sieves are post-treatment methods and direct synthesis methods. Post-treatment methods include acid-dealuminization and alkali-desiliconization methods. Post-treatment methods can selectively generate mesopores and even macropores, but inevitably lead to a loss of zeolite crystallinity and also present waste liquid treatment issues. Direct synthesis methods usually require the addition of a second template agent (carbon nanoparticles, nanotubes, surfactants, cationic polymers, etc.) to interact with silicon and aluminum sources to introduce mesopores. However, the high cost of these template agents and the demanding experimental conditions limit their industrial application.

[0005] For loading metals onto zeolite molecular sieves, current preparation methods are mainly divided into post-treatment methods and one-step synthesis methods. Post-synthesis methods mainly include impregnation and ion exchange methods. Impregnation involves impregnating the zeolite surface and pores with metal ions to adsorb or deposit the metal precursor, which is then converted into the target metal species by calcination. However, impregnation can lead to particle agglomeration and pore blockage. Ion exchange achieves loading by replacing exchangeable cations outside the zeolite framework with metal cations in the solution, but the metal loading capacity is low and the process is complex. One-step methods typically involve directly introducing metal salts or organometallic precursors into the reactive gel in a traditional hydrothermal system. This method introduces metals simultaneously during zeolite crystallization, allowing metal ions to be directly embedded in the framework or uniformly dispersed in the pores, forming a structurally homogeneous metal-zeolite complex. However, one-step synthesis still faces challenges. First, specific synthesis formulations are required to ensure that the zeolite structure is not affected by the introduction of metal ions. Second, the problem of rapid precipitation of metal cations in alkaline zeolite precursor solutions, which hinders their entry into the zeolite pores, needs to be addressed.

[0006] Therefore, the one-step hydrothermal direct synthesis of tungsten-containing hierarchical porous ZSM-5 zeolite molecular sieves without the addition of a second template agent is of great significance, but the synthesis is more challenging and there are currently no related patent reports. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the prior art and provide a tungsten-containing hierarchical porous ZSM-5 zeolite molecular sieve and its preparation method. This method can directly synthesize tungsten-containing hierarchical porous ZSM-5 zeolite molecular sieves in a one-step hydrothermal process without adding a second template agent.

[0008] To achieve the above objectives, this invention discloses a method for preparing a tungsten-containing hierarchical porous ZSM-5 zeolite molecular sieve, comprising the following steps: A reaction system is formed by mixing silicon source, aluminum source, tungsten source, additives, seed crystals, sodium oxide and water. The reaction system is then crystallized and calcined sequentially to obtain a tungsten-containing hierarchical porous ZSM-5 zeolite molecular sieve.

[0009] Furthermore, the silicon source is one or more of tetraethyl orthosilicate, silica sol, and water glass.

[0010] Furthermore, the aluminum source is one or a mixture of aluminum sulfate, aluminum nitrate, sodium aluminate, and aluminum isopropoxide.

[0011] Furthermore, the tungsten source is one or a mixture of tungstic acid, sodium tungstate, and ammonium metatungstate.

[0012] Furthermore, the additive is one or more of tetramethylguanidine, urea, ammonium chloride, and ammonium carbonate.

[0013] Furthermore, the seed crystal is ZSM-5 zeolite.

[0014] Furthermore, the molar ratio of silicon dioxide in the silicon source, aluminum oxide in the aluminum source, tungsten trioxide in the tungsten source, sodium oxide, seed crystals, additives, and water is 1:x:y:z:p:n:m, 0.02≤x≤0.04; <y≤0.03;0.1<z≤0.2;0<p≤0.1;0<n≤0.4;10≤m<30。

[0015] Furthermore, the crystallization temperature is 150-200℃; The crystallization time is 8 to 20 days.

[0016] Furthermore, the process of mixing silicon source, aluminum source, tungsten source, additives, seed crystals, sodium oxide and water to form a reaction system is as follows: sodium oxide is mixed with silicon source and seed crystals, and then tungsten source, aluminum source, water and additives are added and mixed to obtain the reaction system.

[0017] This invention discloses a tungsten-containing hierarchical porous ZSM-5 zeolite molecular sieve, prepared using a method for preparing the tungsten-containing hierarchical porous ZSM-5 zeolite molecular sieve. The tungsten-containing hierarchical porous ZSM-5 zeolite molecular sieve has a mesoporous structure formed by the stacking of zeolite molecular sieve grains, and the mesopore volume is greater than or equal to 0.2 cm³. 3 / g, specific surface area greater than 350 m² 2 / g, wherein the primary particle size of the tungsten-containing hierarchical porous ZSM-5 zeolite molecular sieve is 50-200nm, and the secondary packed particle size is 20-50μm.

[0018] The present invention has the following beneficial effects: The tungsten-containing hierarchical porous ZSM-5 zeolite molecular sieve and its preparation method of this invention involve mixing a silicon source, an aluminum source, a tungsten source, additives, seed crystals, sodium oxide, and water to form a reaction system. This reaction system is then sequentially crystallized and calcined to obtain the tungsten-containing hierarchical porous ZSM-5 zeolite molecular sieve. The key to its formation of numerous mesopores lies in the synergistic effect of the tungsten species, additives, and seed crystals. The introduction of tungsten effectively inhibits anisotropic crystal growth, controlling the primary particle size between 50-200 nm, thus providing a structural basis for the subsequent formation of intergranular mesopores. The additives, through steric hindrance or charge action, promote the assembly of primary nanoparticles into secondary large particles of 20-50 μm in a "non-close-packed" manner, forming abundant intergranular pores between the particles and significantly increasing the mesopore volume. The synthesized tungsten-containing hierarchical porous ZSM-5 zeolite molecular sieve has a large number of mesopores, which can improve the diffusion restriction problem caused by the small pore size of traditional ZSM-5, improve diffusion efficiency, and thus enhance the catalytic activity of the zeolite molecular sieve. In addition, no second template agent needs to be added during the introduction of mesopores, resulting in low cost, simple process, environmental friendliness, and easy operation. The prepared tungsten-containing hierarchical porous ZSM-5 zeolite molecular sieve has high crystallinity, good experimental repeatability, large secondary packing particle size, and is easy to separate in industrial applications. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1a The XRD pattern of the tungsten-containing hierarchical porous ZSM-5 zeolite molecular sieve obtained in Example 1; Figure 1b The image shows a SEM image of the tungsten-containing hierarchical porous ZSM-5 zeolite molecular sieve obtained in Example 1. Figure 2a The image shows the XRD pattern of the tungsten-containing hierarchical porous ZSM-5 zeolite molecular sieve obtained in Example 2. Figure 2b This is a SEM image of the tungsten-containing hierarchical porous ZSM-5 zeolite molecular sieve obtained in Example 2; Figure 3a The image shows the XRD pattern of the tungsten-containing hierarchical porous ZSM-5 zeolite molecular sieve obtained in Example 3. Figure 3b The image shows a SEM image of the tungsten-containing hierarchical porous ZSM-5 zeolite molecular sieve obtained in Example 3. Figure 4a The XRD pattern of the tungsten-containing hierarchical porous ZSM-5 zeolite molecular sieve obtained in Example 4; Figure 4b The image shows a SEM image of the tungsten-containing hierarchical porous ZSM-5 zeolite molecular sieve obtained in Example 4. Figure 5a The XRD pattern of the tungsten-containing hierarchical porous ZSM-5 zeolite molecular sieve obtained in Example 5; Figure 5b This is a SEM image of the tungsten-containing hierarchical porous ZSM-5 zeolite molecular sieve obtained in Example 5; Figure 6a The XRD pattern of the tungsten-free ZSM-5 zeolite molecular sieve prepared in Comparative Example 1 is shown. Figure 6b SEM image of the tungsten-free ZSM-5 zeolite molecular sieve prepared in Comparative Example 1; Figure 7a The XRD pattern of the tungsten-free ZSM-5 zeolite molecular sieve prepared in Comparative Example 2 is shown. Figure 7b The image shows a SEM image of the tungsten-free ZSM-5 zeolite molecular sieve prepared in Comparative Example 2. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] In the description of this invention, it should be understood that the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0023] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0024] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes such combinations. For example, A and / or B can represent three cases: A alone, A and B simultaneously, and B alone. Additionally, the character " / " in this invention generally indicates that the preceding and following objects have an "or" relationship.

[0025] It should be understood that although terms such as first, second, third, etc., may be used in the embodiments of the present invention to describe the preset range, these preset ranges should not be limited to these terms. These terms are only used to distinguish the preset ranges from one another. For example, without departing from the scope of the embodiments of the present invention, the first preset range may also be referred to as the second preset range, and similarly, the second preset range may also be referred to as the first preset range.

[0026] Depending on the context, the word "if" as used here can be interpreted as "when," "when," "in response to determination," or "in response to detection." Similarly, depending on the context, the phrase "if determination" or "if detection (of the stated condition or event)" can be interpreted as "when determination," "in response to determination," "when detection (of the stated condition or event)," or "in response to detection (of the stated condition or event)."

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0028] The accompanying drawings illustrate various structural schematic diagrams according to embodiments disclosed in this invention. These drawings are not to scale, and some details have been enlarged for clarity, and some details may have been omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.

[0029] The preparation method of the tungsten-containing hierarchical porous ZSM-5 zeolite molecular sieve of the present invention includes the following steps: A reaction system is formed by mixing silicon source, aluminum source, tungsten source, additives, seed crystals, sodium oxide and water. The reaction system is then crystallized and calcined sequentially to obtain a tungsten-containing hierarchical porous ZSM-5 zeolite molecular sieve.

[0030] In this embodiment, the silicon source is one or more of tetraethyl orthosilicate, silica sol, and water glass.

[0031] In this embodiment, the aluminum source is one or a mixture of aluminum sulfate, aluminum nitrate, sodium aluminate, and aluminum isopropoxide.

[0032] In this embodiment, the tungsten source is one or a mixture of tungstic acid, sodium tungstate, and ammonium metatungstate.

[0033] In this embodiment, the additive is one or a mixture of tetramethylguanidine, urea, ammonium chloride and ammonium carbonate.

[0034] In this embodiment, the seed crystal is ZSM-5 zeolite.

[0035] In this embodiment, the molar ratio of silicon dioxide to additives in the silicon source is 1:n, 0. <n≤0.4。

[0036] In this embodiment, the molar ratio of silicon dioxide in the silicon source to aluminum oxide in the aluminum source is 1:x, where 0.02≤x≤0.04.

[0037] In this embodiment, the molar ratio of silicon dioxide in the silicon source to tungsten trioxide in the tungsten source is 1:y, where 0 <y≤0.03。

[0038] In this embodiment, the molar ratio of silicon dioxide to sodium oxide in the silicon source is 1:z, where 0.1 <z≤0.2。

[0039] In this embodiment, the molar ratio of silicon dioxide to seed crystal in the silicon source is 1:p, where 0 <p≤0.1。

[0040] In this embodiment, the molar ratio of silicon dioxide to water in the silicon source is 1:m, where 10 ≤ m < 30.

[0041] In this embodiment, the molar ratio of silicon dioxide in the silicon source, aluminum oxide in the aluminum source, tungsten trioxide in the tungsten source, sodium oxide, seed crystals, additives, and water is 1:x:y:z:p:n:m, 0.02≤x≤0.04; <y≤0.03;0.1<z≤0.2;0<p≤0.1;0<n≤0.4;10≤m<30。

[0042] In this embodiment, the crystallization temperature is 150-200℃.

[0043] In this embodiment, the crystallization time is 8 to 20 days.

[0044] In this embodiment, the roasting temperature is 550°C.

[0045] In this embodiment, sodium oxide is mixed with a silicon source and seed crystals, and then an aluminum source, a tungsten source, water and additives are added and mixed to obtain a reaction system. The reaction system is then crystallized and calcined sequentially to obtain a tungsten-containing hierarchical porous ZSM-5 zeolite molecular sieve.

[0046] It should be noted that this invention employs a one-step hydrothermal direct synthesis of tungsten-containing ZSM-5 zeolite molecular sieves with hierarchical pores without adding a second template agent. This ensures the uniform distribution of tungsten species while introducing mesopores to improve the diffusion limitation caused by the small pore size of traditional ZSM-5, thereby enhancing the catalyst's performance.

[0047] The tungsten-containing hierarchical porous ZSM-5 zeolite molecular sieve has a silicon-to-aluminum ratio of 12.5-25, and the zeolite contains tungsten with a molar ratio of tungsten to silicon of 0-0.03. The hierarchical porous ZSM-5 zeolite molecular sieve has a mesoporous structure formed by the accumulation of zeolite molecular sieve grains, and the mesopore volume is not less than 0.2 cm³. 3 / g, specific surface area greater than 350 m² 2 / g, wherein the primary particle size of the zeolite molecular sieve is 50-200nm and the secondary packed particle size is 20-50μm.

[0048] Example 1 The preparation method of the tungsten-containing hierarchical porous ZSM-5 zeolite molecular sieve described in this embodiment includes the following steps: 1) Tungstic acid powder was added to sodium hydroxide solution and mixed evenly to prepare a transparent solution, wherein the molar ratio of silica sol (calculated as silicon dioxide) to sodium oxide was 1:0.2; and the molar ratio of silica sol (calculated as silicon dioxide) to tungstic acid (calculated as tungsten trioxide) was 1:0.01. 2) Add the silica sol and ZSM-5 seed crystals to the solution obtained in step 1), and stir at 60°C for 1-2 hours. The mass ratio of silica sol (based on silicon dioxide) to seed crystals is 1:0.05. 3) Add aluminum sulfate and water to the solution obtained in step 2) and mix evenly. The molar ratio of silica sol (calculated as silicon dioxide) to aluminum sulfate (calculated as aluminum oxide) is 1:0.025; the molar ratio of silica sol (calculated as silicon dioxide) to water is 1:20. Stir at room temperature for 4-8 hours. 4) Add tetramethylguanidine to the solution obtained in step 3), with the molar ratio of silica sol (based on silica) to tetramethylguanidine being 1:0.25; stir at room temperature for 10-60 minutes to obtain the reaction system; 5) Transfer the reaction system obtained in step 4) to a reactor and crystallize at 190°C for 9 days; 6) Remove the crystallized product from the reactor, centrifuge or filter it, wash it with deionized water until neutral and dry it; 7) The calcination was carried out in a muffle furnace at 550°C for 4 hours to obtain a tungsten-containing hierarchical porous ZSM-5 zeolite molecular sieve.

[0049] The morphology and structure of the tungsten-containing hierarchical porous zeolite molecular sieve obtained in this embodiment are as follows: Figure 1a As shown, zeolite molecular sieves macroscopically appear as spherical clusters, while microscopically they are stacked as thin sheets. The primary nanoparticle size is 50-200 nm, and the secondary stacked particle size is 20-50 μm. The XRD data of the zeolite molecular sieve prepared in this embodiment are shown below. Figure 1b As shown in the XRD data, this zeolite molecular sieve possesses an MFI zeolite structure and exhibits high crystallinity. The pore structure of the tungsten-containing hierarchical ZSM-5 zeolite molecular sieve in this embodiment is shown in Table 1, with a specific surface area of ​​432 m². 2 / g, micropore volume is 0.15cm³ 3 / g, mesopore volume is 0.21cm³ 3 / g, total pore volume is 0.42cm³ 3 / g.

[0050] Example 2 This embodiment describes the preparation method of the tungsten-containing hierarchical porous ZSM-5 zeolite molecular sieve, which includes the following steps: 1) Add tungstic acid powder to sodium hydroxide solution and mix evenly to prepare a transparent solution, wherein the molar ratio of water glass (calculated as silicon dioxide) to sodium oxide is 1:0.15; the molar ratio of water glass (calculated as silicon dioxide) to tungstic acid (calculated as tungsten trioxide) is 1:0.01; 2) Add water glass, seed crystals and sulfuric acid to the solution obtained in step 1), stir at 60°C for 1-2 hours. The mass ratio of water glass (based on silicon dioxide) to seed crystals is 1:0.05; the molar ratio of water glass (based on silicon dioxide) to sulfuric acid is 1:0.25. 3) Add aluminum sulfate and water to the solution obtained in step 2), mix evenly, the molar ratio of water glass (calculated as silicon dioxide) to aluminum sulfate (calculated as aluminum oxide) is 1:0.025; the molar ratio of water glass (calculated as silicon dioxide) to water is 1:20; stir at room temperature for 4-8 hours; 4) Add urea to the solution obtained in step 3), with the molar ratio of water glass (calculated as silicon dioxide) to urea being 1:0.25; stir at room temperature for 10-60 minutes to obtain the reaction system; 5) Transfer the reaction system obtained in step 4) to a reactor and crystallize at 180°C for 11 days; 6) Remove the crystallized product from the reactor, centrifuge or filter it, wash it with deionized water until neutral and dry it; 7) The calcination was carried out in a muffle furnace at 550°C for 4 hours to obtain a tungsten-containing hierarchical porous ZSM-5 zeolite molecular sieve.

[0051] The morphology and structure of the zeolite molecular sieve obtained in this embodiment are as follows: Figure 2a As shown, zeolite molecular sieves macroscopically appear as spherical clusters, while microscopically they are stacked as thin sheets. The primary nanoparticle size is 50-200 nm, and the secondary stacked particle size is 20-50 μm. The XRD data of the zeolite molecular sieve prepared in this embodiment are shown below. Figure 2b As shown in Table 1, the XRD data reveals that this zeolite molecular sieve possesses an MFI zeolite structure and exhibits high crystallinity. The pore structure of the tungsten-containing hierarchical ZSM-5 zeolite molecular sieve in this embodiment is shown in Table 1, with a specific surface area of ​​395 m². 2 / g, micropore volume is 0.13cm³ 3 / g, mesopore volume is 0.19cm³ 3 / g, total pore volume is 0.4cm³ 3 / g.

[0052] Example 3 The preparation method of the tungsten-containing hierarchical porous ZSM-5 zeolite molecular sieve described in this embodiment includes the following steps: 1) Tungstic acid powder was added to sodium hydroxide solution and mixed evenly to prepare a transparent solution, wherein the molar ratio of silica sol (calculated as silicon dioxide) to sodium oxide was 1:0.1925; and the molar ratio of silica sol (calculated as silicon dioxide) to tungstic acid (calculated as tungsten trioxide) was 1:0.01. 2) Add the silica sol and seed crystals to the solution obtained in step 1), and stir at 60°C for 1-2 hours. The molar ratio of silica sol (based on silicon dioxide) to seed crystals is 1:0.05. 3) Add sodium aluminate and water to the solution obtained in step 2), mix evenly, the molar ratio of silica sol (calculated as silicon dioxide) to sodium aluminate (calculated as aluminum oxide) is 1:0.025; the molar ratio of silica sol (calculated as silicon dioxide) to water is 1:20; stir at room temperature for 4-8 hours; 4) Add ammonium chloride to the solution obtained in step 3), with the molar ratio of silica sol (calculated as silicon dioxide) to ammonium chloride being 1:0.25; stir at room temperature for 10-60 minutes to obtain the reaction system; 5) Transfer the reaction system obtained in step 4) to a reactor and crystallize at 190°C for 11 days; 6) Remove the crystallized product from the reactor, centrifuge or filter it, wash it thoroughly with deionized water until neutral, and dry it. 7) The calcination was carried out in a muffle furnace at 550°C for 4 hours to obtain a tungsten-containing hierarchical porous ZSM-5 zeolite molecular sieve.

[0053] The morphology and structure of the zeolite molecular sieve obtained in this embodiment are as follows: Figure 3a As shown, zeolite molecular sieves macroscopically appear as spherical clusters, while microscopically they are stacked as thin sheets. The primary nanoparticle size is 50-200 nm, and the secondary stacked particle size is 20-50 μm. The XRD data of the zeolite molecular sieve prepared in this embodiment are shown below. Figure 3b As shown in Table 1, the XRD data reveals that this zeolite molecular sieve possesses an MFI zeolite structure and exhibits high crystallinity. The pore structure of the tungsten-containing hierarchical ZSM-5 zeolite molecular sieve in this embodiment is shown in Table 1, with a specific surface area of ​​382 m². 2 / g, micropore volume is 0.15cm³ 3 / g, mesopore volume is 0.23cm³ 3 / g, total pore volume is 0.43cm³ 3 / g.

[0054] Example 4 The preparation method of the tungsten-containing hierarchical porous ZSM-5 zeolite molecular sieve described in this embodiment includes the following steps: 1) Tungstic acid powder was added to sodium hydroxide solution and mixed evenly to prepare a transparent solution, wherein the molar ratio of silica sol (calculated as silicon dioxide) to sodium oxide was 1:0.2; and the molar ratio of silica sol (calculated as silicon dioxide) to tungstic acid (calculated as tungsten trioxide) was 1:0.01. 2) Add the silica sol and seed crystals to the solution obtained in step 1), and stir at 60°C for 1-2 hours. The molar ratio of silica sol (based on silicon dioxide) to seed crystals is 1:0.05. 3) Add aluminum sulfate and water to the solution obtained in step 2), mix evenly, the molar ratio of silica sol (calculated as silicon dioxide) to aluminum sulfate (calculated as aluminum oxide) is 1:0.033; the molar ratio of silica sol (calculated as silicon dioxide) to water is 1:20; stir at room temperature for 4-8 hours; 4) Add ammonium carbonate to the solution obtained in step 3), with the molar ratio of silica sol (calculated as silicon dioxide) to ammonium carbonate being 1:0.25; stir at room temperature for 10-60 minutes to obtain the reaction system; 5) Transfer the reaction system obtained in step (4) to a reactor and crystallize at 190°C for 12 days; 6) Remove the crystallized product from the reactor, centrifuge or filter it, wash it thoroughly with deionized water until neutral, and dry it. 7) The calcination was carried out in a muffle furnace at 550°C for 4 hours to obtain a tungsten-containing hierarchical porous ZSM-5 zeolite molecular sieve.

[0055] The morphology and structure of the zeolite molecular sieve obtained in this embodiment are as follows: Figure 4aAs shown, zeolite molecular sieves macroscopically appear as spherical clusters, while microscopically they are stacked as thin sheets. The primary nanoparticle size is 50-200 nm, and the secondary stacked particle size is 20-50 μm. The XRD data of the zeolite molecular sieve prepared in this embodiment are shown below. Figure 4b As shown in Table 1, the XRD data reveals that this zeolite molecular sieve possesses an MFI zeolite structure and exhibits high crystallinity. The pore structure of the tungsten-containing hierarchical ZSM-5 zeolite molecular sieve in this embodiment is shown in Table 1, with a specific surface area of ​​411 m². 2 / g, micropore volume is 0.14cm³ 3 / g, mesopore volume is 0.24cm³ 3 / g, total pore volume is 0.43cm³ 3 / g.

[0056] Example 5 The preparation method of the tungsten-containing hierarchical porous ZSM-5 zeolite molecular sieve described in this embodiment includes the following steps: 1) Tungstic acid powder was added to sodium hydroxide solution and mixed evenly to prepare a transparent solution. The molar ratio of silica sol (calculated as silicon dioxide) to sodium oxide was 1:0.2; the molar ratio of silica sol (calculated as silicon dioxide) to tungstic acid (calculated as tungsten trioxide) was 1:0.03. 2) Add the silica sol and seed crystals to the solution obtained in step 1), and stir at 60°C for 1-2 hours. The molar ratio of silica sol (based on silicon dioxide) to seed crystals is 1:0.05. 3) Add aluminum sulfate and water to the solution obtained in step 2), mix evenly, the molar ratio of silica sol (calculated as silicon dioxide) to aluminum sulfate (calculated as aluminum oxide) is 1:0.025; the molar ratio of silica sol (calculated as silicon dioxide) to water is 1:20; stir at room temperature for 4-8 hours; 4) Add ammonium carbonate to the solution obtained in step 3), with the molar ratio of silica sol (calculated as silica) to ammonium carbonate being 1:0.25; stir at room temperature for 10-60 minutes to obtain the reaction system; 5) Transfer the reaction system obtained in step 4) to a reactor and crystallize at 190°C for 16 days; 6) Remove the crystallized product from the reactor, centrifuge or filter it, wash it thoroughly with deionized water until neutral, and dry it. 7) The calcination was carried out in a muffle furnace at 550°C for 4 hours to obtain a tungsten-containing hierarchical porous ZSM-5 zeolite molecular sieve.

[0057] The morphology and structure of the zeolite molecular sieve obtained in this embodiment are as follows: Figure 5aAs shown, zeolite molecular sieves macroscopically appear as spherical clusters, while microscopically they are stacked as thin sheets. The primary nanoparticle size is 50-200 nm, and the secondary stacked particle size is 20-50 μm. The XRD data of the zeolite molecular sieve prepared in this embodiment are shown below. Figure 5b As shown in the XRD data, this zeolite molecular sieve possesses an MFI zeolite structure and exhibits high crystallinity. The pore structure of the tungsten-containing hierarchical ZSM-5 zeolite molecular sieve in this embodiment is shown in Table 1, with a specific surface area of ​​431 m². 2 / g, micropore volume is 0.13cm³ 3 / g, mesopore volume is 0.28cm³ 3 / g, total pore volume is 0.46cm³ 3 / g.

[0058] Comparative Example 1 The preparation method of the tungsten-free ZSM-5 zeolite molecular sieve described in this comparative example includes the following steps: 1) The molar ratio of silica sol (based on silicon dioxide) to sodium oxide is 1:0.2; the molar ratio of silica sol (based on silicon dioxide) to seed crystals is 1:0.05; mix the silica sol, seed crystals, and sodium hydroxide solution evenly and stir at 60°C for 1-2 hours. 2) Add aluminum sulfate and water to the solution obtained in step 1), mix evenly, the molar ratio of silica sol (calculated as silicon dioxide) to aluminum sulfate (calculated as aluminum oxide) is 1:0.033; the molar ratio of silica sol (calculated as silicon dioxide) to water is 1:20; stir at room temperature for 4-8 hours; 3) Add the additive to the solution obtained in step 2), with the molar ratio of silica sol (calculated as silica) to additive being 1:0.25; stir at room temperature for 10-60 minutes to obtain the reaction system; 4) Transfer the reaction system obtained in step 3) to a reactor and crystallize at 170°C for 6 days; 5) Remove the crystallized product from the reactor, centrifuge or filter it, wash it thoroughly with deionized water until neutral, and dry it. 6) The ZSM-5 zeolite molecular sieve was heated to 550℃ in a muffle furnace and calcined for 4 hours to obtain tungsten-free ZSM-5 zeolite molecular sieve.

[0059] The morphology and structure of the molecular sieve obtained in this embodiment are as follows: Figure 6a As shown, the molecular sieve crystals exhibit a classic coffin-like shape, approximately 5 μm in length and 1 μm in thickness. The XRD data of the molecular sieve prepared in this embodiment are as follows: Figure 6b As shown in the figure. XRD data reveals that this molecular sieve possesses an MFI zeolite structure.

[0060] Comparative Example 2 The preparation method of the tungsten-free ZSM-5 zeolite molecular sieve described in this comparative example includes the following steps: 1) The molar ratio of silica sol (based on silicon dioxide) to sodium oxide is 1:0.25; the molar ratio of silica sol (based on silicon dioxide) to seed crystals is 1:0.05; mix the silica sol, seed crystals, and sodium hydroxide solution evenly and stir at 60°C for 1-2 hours. 2) Add aluminum sulfate and water to the solution obtained in step 1) and mix them evenly to prepare a solution. The molar ratio of silica sol (calculated as silicon dioxide) to aluminum sulfate (calculated as aluminum oxide) is 1:0.033; the molar ratio of silica sol (calculated as silicon dioxide) to water is 1:20; stir at room temperature for 4-8 hours. 3) Add the additive to the solution obtained in step 2), with the molar ratio of silica sol (calculated as silica) to additive being 1:0.25; stir at room temperature for 10-60 minutes to obtain the reaction system; 4) Transfer the reaction system obtained in step 3) to a reactor and crystallize at 170°C for 4 days; 5) Remove the crystallized product from the reactor, centrifuge or filter it, wash it thoroughly with deionized water until neutral, and dry it. 6) The ZSM-5 zeolite molecular sieve was heated to 550℃ in a muffle furnace and calcined for 4 hours to obtain tungsten-free ZSM-5 zeolite molecular sieve.

[0061] The morphology and structure of the molecular sieve obtained in this embodiment are as follows: Figure 7a As shown, the molecular sieve crystals are plate-like, approximately 500 nm thick, with an in-plane dimension of approximately 4 μm. The XRD data of the molecular sieve prepared in this embodiment are as follows: Figure 7b As shown in the figure. XRD data reveals that this molecular sieve possesses an MFI zeolite structure.

[0062] The samples obtained from Examples 1, 2, 3, 4, 5, Comparative Example 1, and Comparative Example 2 were subjected to nitrogen adsorption-desorption tests. The test conditions were as follows: 100 mg of the sample was degassed under vacuum at 250 °C for 6 hours, and then tested by a nitrogen adsorption-desorption analyzer. The results are shown in Table 1. The specific surface area and pore volume were obtained by nitrogen adsorption-desorption, and the data were provided by the detector.

[0063] Table 1

[0064] Table 1 shows that the ZSM-5 zeolite molecular sieves obtained by adjusting the silicon source, aluminum source, metal loading, and silicon-aluminum ratio in Examples 1, 2, 3, 4, and 5 all have high specific surface areas (>380 cm²). 3 / g), external specific surface area (>70cm²) 3 / g) and total pore volume (>0.35cm³)3 The zeolite molecular sieves exhibit a high mesoporous content, accounting for over 50% of the pore volume. The tungsten-free ZSM-5 zeolite molecular sieves obtained by controlling sodium oxide in Comparative Examples 1 and 2 both possess high specific surface areas (>390 cm²). 3 / g), but the micropore content of zeolite molecular sieves is dominant.

[0065] Example 6 The preparation method of the tungsten-containing hierarchical porous ZSM-5 zeolite molecular sieve of the present invention includes the following steps: A reaction system is formed by mixing silicon source, aluminum source, tungsten source, additives, seed crystals, sodium oxide and water. The reaction system is then crystallized and calcined sequentially to obtain a tungsten-containing hierarchical porous ZSM-5 zeolite molecular sieve.

[0066] In this embodiment, the silicon source is tetraethyl orthosilicate.

[0067] In this embodiment, the aluminum source is aluminum nitrate.

[0068] In this embodiment, the tungsten source is sodium tungstate.

[0069] In this embodiment, the additive is a mixture of tetramethylguanidine, urea, ammonium chloride and ammonium carbonate.

[0070] In this embodiment, the seed crystal is ZSM-5 zeolite.

[0071] In this embodiment, the molar ratio of silicon dioxide in the silicon source, aluminum oxide in the aluminum source, tungsten trioxide in the tungsten source, sodium oxide, seed crystals, additives, and water is 1:0.02:0.01:0.11:0.1:0.01:15; In this embodiment, the crystallization temperature is 150°C.

[0072] In this embodiment, the crystallization time is 15 days.

[0073] In this embodiment, the roasting temperature is 550°C.

[0074] Example 7 The preparation method of the tungsten-containing hierarchical porous ZSM-5 zeolite molecular sieve of the present invention includes the following steps: A reaction system is formed by mixing silicon source, aluminum source, tungsten source, additives, seed crystals, sodium oxide and water. The reaction system is then crystallized and calcined sequentially to obtain a tungsten-containing hierarchical porous ZSM-5 zeolite molecular sieve.

[0075] In this embodiment, the silicon source is a mixture of silica sol and water glass.

[0076] In this embodiment, the aluminum source is aluminum isopropoxide.

[0077] In this embodiment, the tungsten source is ammonium metatungstate.

[0078] In this embodiment, the additive is a mixture of ammonium chloride and ammonium carbonate.

[0079] In this embodiment, the seed crystal is ZSM-5 zeolite.

[0080] In this embodiment, the molar ratio of silicon dioxide in the silicon source, aluminum oxide in the aluminum source, tungsten trioxide in the tungsten source, sodium oxide, seed crystals, additives, and water is 1:0.04:0.02:0.15:0.05:0.4:29; In this embodiment, the crystallization temperature is 200°C.

[0081] In this embodiment, the crystallization time is 10 days.

[0082] In this embodiment, the roasting temperature is 550°C.

[0083] Example 8 The preparation method of the tungsten-containing hierarchical porous ZSM-5 zeolite molecular sieve of the present invention includes the following steps: A reaction system is formed by mixing silicon source, aluminum source, tungsten source, additives, seed crystals, sodium oxide and water. The reaction system is then crystallized and calcined sequentially to obtain a tungsten-containing hierarchical porous ZSM-5 zeolite molecular sieve.

[0084] In this embodiment, the silicon source is a mixture of tetraethyl orthosilicate, silica sol, and water glass.

[0085] In this embodiment, the aluminum source is a mixture of aluminum sulfate, aluminum nitrate, sodium aluminate, and aluminum isopropoxide.

[0086] In this embodiment, the tungsten source is a mixture of tungstic acid, sodium tungstate, and ammonium metatungstate.

[0087] In this embodiment, the additive is a mixture of tetramethylguanidine, urea, ammonium chloride and ammonium carbonate.

[0088] In this embodiment, the seed crystal is ZSM-5 zeolite.

[0089] In this embodiment, the molar ratio of silicon dioxide in the silicon source, aluminum oxide in the aluminum source, tungsten trioxide in the tungsten source, sodium oxide, seed crystals, additives, and water is 1:0.03:0.01:0.18:0.08:0.3:28; In this embodiment, the crystallization temperature is 180°C.

[0090] In this embodiment, the crystallization time is 9 days.

[0091] In this embodiment, the roasting temperature is 550°C.

[0092] It should be noted that this invention uses a one-step hydrothermal method to introduce tungsten into the framework and channels of ZSM-5 zeolite, thereby achieving the preparation of highly dispersed metal or metal oxide tungsten-containing ZSM-5 catalysts. At the same time, without adding a second template agent, a hierarchical porous structure is introduced, thereby improving the molecular diffusion performance of the catalyst, which has great advantages in industrial separation.

[0093] Other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and disclosure of the invention. This application is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of the invention are indicated by the following claims.

[0094] It should be understood that the present invention is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the invention is limited only by the appended claims.

[0095] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the present invention. Any simple modifications, alterations, or equivalent structural changes made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for preparing a tungsten-containing hierarchical porous ZSM-5 zeolite molecular sieve, characterized in that, Includes the following steps: A reaction system is formed by mixing silicon source, aluminum source, tungsten source, additives, seed crystals, sodium oxide and water. The reaction system is then crystallized and calcined sequentially to obtain a tungsten-containing hierarchical porous ZSM-5 zeolite molecular sieve.

2. The method for preparing the tungsten-containing hierarchical porous ZSM-5 zeolite molecular sieve according to claim 1, characterized in that, The silicon source is one or more of tetraethyl orthosilicate, silica sol, and water glass, or a mixture thereof.

3. The method for preparing the tungsten-containing hierarchical porous ZSM-5 zeolite molecular sieve according to claim 1, characterized in that, The aluminum source is one or a mixture of aluminum sulfate, aluminum nitrate, sodium aluminate, and aluminum isopropoxide.

4. The method for preparing the tungsten-containing hierarchical porous ZSM-5 zeolite molecular sieve according to claim 1, characterized in that, The tungsten source is one or a mixture of tungstic acid, sodium tungstate, and ammonium metatungstate.

5. The method for preparing the tungsten-containing hierarchical porous ZSM-5 zeolite molecular sieve according to claim 1, characterized in that, The additive is one or more of tetramethylguanidine, urea, ammonium chloride and ammonium carbonate.

6. The method for preparing the tungsten-containing hierarchical porous ZSM-5 zeolite molecular sieve according to claim 1, characterized in that, The seed crystal is ZSM-5 zeolite.

7. The method for preparing the tungsten-containing hierarchical porous ZSM-5 zeolite molecular sieve according to claim 1, characterized in that, The molar ratio of silicon dioxide in the silicon source, aluminum oxide in the aluminum source, tungsten trioxide in the tungsten source, sodium oxide, seed crystals, additives, and water is 1:x:y:z:p:n:m, 0.02≤x≤0.04; <y≤0.03;0.1<z≤0.2;0<p≤0.1;0<n≤0.4;10≤m<30。 8. The method for preparing the tungsten-containing hierarchical porous ZSM-5 zeolite molecular sieve according to claim 1, characterized in that, The crystallization temperature is 150-200℃; The crystallization time is 8 to 20 days.

9. The method for preparing the tungsten-containing hierarchical porous ZSM-5 zeolite molecular sieve according to claim 1, characterized in that, The process of mixing silicon source, aluminum source, tungsten source, additives, seed crystals, sodium oxide and water to form a reaction system is as follows: sodium oxide is mixed with silicon source and seed crystals, and then tungsten source, aluminum source, water and additives are added and mixed to obtain the reaction system.

10. A tungsten-containing hierarchical porous ZSM-5 zeolite molecular sieve, characterized in that, The tungsten-containing hierarchical porous ZSM-5 zeolite molecular sieve is prepared according to the preparation method of any one of claims 1-9. The tungsten-containing hierarchical porous ZSM-5 zeolite molecular sieve has a mesoporous structure formed by the stacking of zeolite molecular sieve grains, and the mesopore volume is greater than or equal to 0.2 cm³. 3 / g, specific surface area greater than 350 m² 2 / g, wherein the primary particle size of the tungsten-containing hierarchical porous ZSM-5 zeolite molecular sieve is 50-200nm, and the secondary packed particle size is 20-50μm.

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