Molecular sieve catalyst as well as preparation method and application thereof
By using a method without using a template agent, a molecular sieve catalyst with a microporous-mesoporous multi-stage pore structure is used to form a molecular sieve catalyst with a microporous-mesoporous multi-stage pore structure without using a template agent, which solves the problems of carbon deposit deactivation and environmental pollution in the prior art, and achieves an efficient methane oxygen-free aromatization reaction.
Patent Information
- Application Number
- CN202510494690.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-18
- Publication Date
- 2025-07-18
AI Technical Summary
The existing molecular sieve catalysts have problems with carbon deactivation in methane oxygen-free aromatization reaction, and the use of organic template agents during the synthesis process is expensive and polluted the environment. The synthetic zeolite molecular sieve has a microporous structure that is not conducive to the diffusion of reactants and products.
Using a method without using template agents, a molecular sieve catalyst with a microporous-mesoporous multi-level pore structure is formed by modifying the molecular sieve seeds without using template agents, and a molecular sieve skeleton silicon species that modify the molecular sieve seeds to remove the molecular sieve seeds to form a mesoporous structure.
The prepared molecular sieve catalyst has good anti-carbon deposit properties and catalytic reaction activity, which improves the catalytic performance and reaction stability of methane oxygen-free aromatization reaction and reduces production costs.
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Figure CN120325316A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of molecular sieve preparation, and particularly relates to a molecular sieve catalyst, a preparation method thereof, and an application thereof. Background Art
[0002] The development and effective utilization of natural gas (methane) resources represent the development direction of the contemporary energy structure, and are also one of the guarantees for sustainable development and an important way for energy greening. How to efficiently utilize methane has become an important link restricting the development of the energy industry. The most ideal methane activation and conversion route in the prior art is the direct conversion of methane without oxygen. Under anaerobic conditions, the over-oxidation of methane or products can be effectively avoided, the emission of greenhouse gas CO2 is inhibited, and thus the utilization rate of C atoms is improved.
[0003] The prior art usually uses a catalyst to catalyze the anaerobic aromatization reaction of CH4, but the rapid carbon deposition and deactivation of the catalyst restrict its further industrial scale-up. In order to reduce the reaction carbon deposition, zeolite molecular sieve materials are used as catalysts. However, in the synthesis process of molecular sieve catalysts at the present stage, an organic template agent is required to direct the synthesis of zeolite molecular sieves. Common organic template agents include tetrapropylammonium hydroxide, tetrapropylammonium bromide, tetraethylammonium hydroxide, n-butylamine, etc. The use of these organic template agents not only has high costs, but also pollutes the environment. Although there is a prior art that has successfully synthesized various zeolite molecular sieves, including Beta, ZSM-5, ZSM-48 and other zeolites, by simply adding a small amount of seed crystals in the absence of an organic template agent, these synthesized zeolite molecular sieves are all microporous structures, which are not conducive to the diffusion of reactants and products, and have the defect of poor anti-carbon deposition performance. Summary of the Invention
[0004] The purpose of the present invention is to provide a molecular sieve catalyst, a preparation method thereof, and an application thereof. In the preparation process of the molecular sieve catalyst of the present invention, no template agent is used, and the prepared molecular sieve catalyst has a microporous-mesoporous hierarchical pore structure, which is conducive to molecular diffusion and has good anti-carbon deposition performance.
[0005] In order to achieve the purpose of the present invention, the present invention provides the following technical solutions:
[0006] A preparation method of a molecular sieve catalyst, without using a template agent, comprising the following steps:
[0007] Mix an aluminum source, a silicon source, a molybdenum-containing active component, and a modified molecular sieve seed crystal, carry out hydrothermal crystallization, and obtain the molecular sieve catalyst after calcination; the modified molecular sieve seed crystal is an acid-modified molecular sieve seed crystal or a base-modified molecular sieve seed crystal.
[0008] Preferably, the base reagent used for the base modification is one or more of strong bases, weak bases, and basic salts;
[0009] The acid reagent used for the acid modification is one or more of strong acids, weak acids, and acid salts.
[0010] Preferably, the concentrations of the base reagent and the acid reagent are independently 0.1 - 5.0 mol / L.
[0011] Preferably, the molecular sieve seed is a zeolite molecular sieve seed.
[0012] Preferably, the aluminum source includes one or several of sodium aluminate, alumina, boehmite, aluminum isopropoxide, and aluminum hydroxide;
[0013] The silicon source includes one or several of silica sol, silicon dioxide, fumed silica, and tetraethyl orthosilicate;
[0014] The molybdenum-containing active component is one or several of ammonium molybdate, sodium molybdate, and zinc molybdate.
[0015] Preferably, the molar ratio of the aluminum source, the silicon source, the molybdenum-containing active component, and the modified molecular sieve seed is 1 - 10:50 - 500:1 - 100:1 - 50.
[0016] Preferably, the temperature of the acid modification or the base modification is 10 - 100 °C, and the time is 2 - 50 h.
[0017] Preferably, the temperature of the hydrothermal crystallization is 100 - 200 °C, and the time is 6 - 120 h;
[0018] The temperature of the calcination is 400 - 700 °C, and the time is 2 - 10 h.
[0019] The present invention also provides a molecular sieve catalyst prepared by the preparation method described in the above technical solution. The molecular sieve catalyst has a microporous-mesoporous hierarchical pore structure; the average pore diameter of the molecular sieve catalyst is 2 - 50 nm.
[0020] The present invention also provides the application of the molecular sieve catalyst described in the above technical solution in the catalytic dehydrogenation of light alkanes to aromatics reaction; the light alkanes are alkanes with 1 - 4 carbon atoms.
[0021] The present invention provides a preparation method of a molecular sieve catalyst without using a template agent, which includes the following steps: mixing an aluminum source, a silicon source, a molybdenum-containing active component, and a modified molecular sieve seed, performing hydrothermal crystallization, and calcining to obtain the molecular sieve catalyst; the modified molecular sieve seed is an acid-modified molecular sieve seed or a base-modified molecular sieve seed. The present invention removes the framework silicon species of the molecular sieve seed through base modification and removes the framework aluminum species of the molecular sieve through acid modification. Through the modification treatment, a mesoporous structure can be formed, turning the originally microporous molecular sieve into a microporous-mesoporous hierarchical pore structure. And in the preparation process of the present invention, no template agent is used, and the preparation method is not only simple and environmentally friendly, but also can greatly reduce the production cost of the hierarchical pore molecular sieve.
[0022] The molecular sieve catalyst prepared by the present invention has a microporous-mesoporous hierarchical pore structure. The relatively large average pore diameter is beneficial to molecular diffusion, and it has good anti-coking performance and catalytic reaction activity. At the same time, it has good crystallinity, which further improves the catalytic performance and reaction stability of the non-oxidative aromatization reaction of methane. BRIEF DESCRIPTION OF THE DRAWINGS
[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.
[0024] Figure 1 It is the X-ray diffraction pattern of the ZSM-5 molecular sieve catalyst and the ZSM-5 molecular sieve seed obtained in Example 4;
[0025] Figure 2 It is the scanning electron microscope images of the ZSM-5 molecular sieve catalyst and the ZSM-5 molecular sieve seed obtained in Example 4; among them, (a) is the ZSM-5 molecular sieve seed, and (b) is the ZSM-5 molecular sieve catalyst;
[0026] Figure 3 It is the N2 adsorption / desorption isotherm and pore size distribution diagram of the ZSM-5 molecular sieve catalyst and the ZSM-5 molecular sieve seed obtained in Example 4; among them, (a) is the N2 adsorption / desorption isotherm, and (b) is the pore size distribution diagram;
[0027] Figure 4 It is the coking amount diagram during the catalytic aromatization reaction of methane of the ZSM-5 molecular sieve catalyst and the ZSM-5 seed obtained in Example 4. DETAILED DESCRIPTION OF THE INVENTION
[0028] The present invention provides a method for preparing a molecular sieve catalyst without using a template agent, which includes the following steps:
[0029] Mix an aluminum source, a silicon source, a molybdenum-containing active component and a modified molecular sieve seed, carry out hydrothermal crystallization, and obtain the molecular sieve catalyst after calcination; the modified molecular sieve seed is an acid-modified molecular sieve seed or a base-modified molecular sieve seed.
[0030] In the present invention, unless otherwise specified, all preparation raw materials are commercially available products well-known to those skilled in the art.
[0031] In the present invention, the modified molecular sieve seeds are acid-modified molecular sieve seeds or alkali-modified molecular sieve seeds; the molecular sieve seeds are zeolite molecular sieve seeds; the zeolite molecular sieve includes one of Beta, ZSM-5, and ZSM-48, and in a specific embodiment, it can be ZSM-5; the alkali reagent used for alkali modification is one or more of strong bases, weak bases, and basic salts, the strong base is sodium hydroxide solution or potassium hydroxide solution, the weak base is ammonia water, and the basic salt is sodium carbonate solution or sodium acetate solution; the acid reagent used for acid modification is one or more of strong acids, weak acids, and acidic salts; the strong acid is one of hydrochloric acid, sulfuric acid solution, and nitric acid solution; the weak acid is acetic acid solution or carbonic acid solution; the acidic salt is ammonium chloride solution; in a specific embodiment, it can be hydrochloric acid solution or sodium hydroxide solution; the concentrations of the alkali reagent and the acid reagent are independently 0.1 to 5.0 mol / L; in a specific embodiment, it can be 0.2 mol / L, 0.4 mol / L, 1 mol / L, 1.5 mol / L, or 3 mol / L. In the present invention, the framework silicon species of the molecular sieve seeds are removed by alkali modification, and the framework aluminum species of the molecular sieve are removed by acid modification. Through the modification treatment, a mesoporous structure can be formed, turning the originally microporous molecular sieve into a microporous-mesoporous hierarchical pore structure.
[0032] In the present invention, there are no special limitations on the dosages of the alkali reagent or the acid reagent and the molecular sieve seeds; in a specific embodiment of the present invention, the solid-liquid ratio of the alkali reagent or the acid reagent to the molecular sieve seeds can be 1 to 100 g:1 L, and in a specific embodiment, it can be 10 g:1 L, 50 g:1 L, or 80 g:1 L.
[0033] In the present invention, the acid modification or alkali modification is to mix the molecular sieve seeds with the alkali reagent or the acid reagent for modification, and the acid-modified molecular sieve seeds or alkali-modified molecular sieve seeds are obtained after the first calcination; the temperature of the acid modification or alkali modification is 10 to 100 °C, and in a specific embodiment, it can be 20, 40, or 60 °C, and the time is 2 to 50 h, and in a specific embodiment, it can be 5, 10, 20, or 40 h; the modification is carried out under stirring conditions, and the present invention has no special limitations on the stirring rate.
[0034] In the present invention, the temperature of the first calcination is 400 to 700 °C, and in a specific embodiment, it can be 500, 550, or 600 °C, and the time is 2 to 10 h, and in a specific embodiment, it can be 3, 5, or 7 h.
[0035] In the present invention, after the acid modification or alkali modification, it also includes drying the obtained product; the temperature of the drying is 80 to 150 °C, and in a specific embodiment, it can be 90 or 120 °C; the time is 2 to 20 h, and in a specific embodiment, it can be 5, 10, or 18 h.
[0036] In the present invention, an aluminum source, a silicon source, a molybdenum-containing active component, and a modified molecular sieve seed are mixed and subjected to hydrothermal crystallization, and the molecular sieve catalyst is obtained after calcination. In the present invention, the aluminum source includes one or more of sodium aluminate, alumina, boehmite, aluminum isopropoxide, and aluminum hydroxide, and in a specific embodiment, it can be sodium aluminate; the silicon source includes one or more of silica sol, silicon dioxide, white carbon black, and tetraethyl orthosilicate, and in a specific embodiment, it can be tetraethyl orthosilicate; the molybdenum-containing active component is one or more of ammonium molybdate, sodium molybdate, and zinc molybdate, and in a specific embodiment, it can be ammonium tetrathiomolybdate, ammonium molybdate tetrahydrate, or ammonium heptamolybdate. In the present invention, ammonium molybdate is used as the active component, which mainly plays a role in activating methane and breaking the C-H bond of methane.
[0037] In the present invention, the molar ratio of the aluminum source, the silicon source, the molybdenum-containing active component, and the modified molecular sieve seed is 1 to 10:50 to 500:1 to 100:1 to 50, and in a specific embodiment, it can be 5:100:100:10, 10:200:50:10, or 5:100:10:10.
[0038] In the present invention, the temperature for mixing the aluminum source, the silicon source, the molybdenum-containing active component, and the modified molecular sieve seed is 10 to 40 °C, and the time is 2 to 40 h.
[0039] In the present invention, the temperature of the hydrothermal crystallization is 100 to 200 °C, and in a specific embodiment, it can be 120 or 150 °C, and the time is 6 to 120 h, and in a specific embodiment, it can be 10, 20, 40, or 60 h; the hydrothermal crystallization is carried out in a stainless steel autoclave made of polytetrafluoroethylene. In the hydrothermal crystallization process of the present invention, the silicon source is hydrolyzed first, and then grows on the surface of the hierarchical pore seed with the structure of silicon oxygen tetrahedron and the aluminum source, thereby forming hierarchical pore ZSM-5 molecular sieve.
[0040] In the present invention, the temperature of the calcination is 400 to 700 °C, and in a specific embodiment, it can be 500, 550, or 600 °C, and the time is 2 to 10 h, and in a specific embodiment, it can be 3, 5, or 7 h.
[0041] In the present invention, after the hydrothermal crystallization, it further includes drying the obtained product, and the drying is the same as the above drying.
[0042] The present invention also provides a molecular sieve catalyst prepared by the preparation method described in the above technical solution, and the molecular sieve catalyst has a microporous-mesoporous hierarchical pore structure.
[0043] In the present invention, the average pore diameter of the molecular sieve catalyst is 2 to 50 nm, and in a specific embodiment, it can be 3.9 nm, 5 nm, 10 nm, or 20 nm.
[0044] The present invention also provides an application of the molecular sieve catalyst described in the above technical solution in the catalytic dehydrogenation aromatization reaction of light alkanes; the light alkanes are alkanes with 1 to 4 carbon atoms, and in specific embodiments, they can be methane, ethane or propane.
[0045] In order to further illustrate the present invention, the molecular sieve catalyst provided by the present invention, its preparation method and application will be described in detail below with reference to the accompanying drawings and embodiments, but they should not be construed as limiting the protection scope of the present invention.
[0046] Example 1
[0047] Mix 1 g of ZSM-5 seeds evenly with 0.2 mol / L hydrochloric acid solution (the ZSM-5 seeds are completely immersed in the hydrochloric acid solution), stir at 20 °C for 20 h, wash with deionized water, dry at 80 °C for 10 h, and calcine at 500 °C for 2 h to obtain modified ZSM-5 seeds;
[0048] Mix sodium aluminate, tetraethyl orthosilicate, ammonium heptamolybdate and modified ZSM-5 seeds evenly according to a molar ratio of 1:100:5:10, stir at 20 °C for 2 h to obtain a gel mixture; put the obtained gel mixture into a stainless steel autoclave lined with polytetrafluoroethylene, seal it and put it into an oven, carry out hydrothermal crystallization at 180 °C for 12 h to obtain a catalyst precursor; wash the obtained catalyst precursor with deionized water, dry at 80 °C for 10 h, and calcine at 500 °C for 4 h to obtain a hierarchical pore structure ZSM-5 molecular sieve catalyst.
[0049] Example 2
[0050] Mix 1 g of ZSM-5 seeds evenly with 0.4 mol / L sodium hydroxide solution, stir at 20 °C for 20 h, wash with deionized water, dry at 80 °C for 12 h, and calcine at 600 °C for 2 h to obtain modified ZSM-5 seeds;
[0051] Mix sodium aluminate, tetraethyl orthosilicate, ammonium heptamolybdate and modified ZSM-5 seeds evenly according to a molar ratio of 1:100:10:5, stir at 20 °C for 6 h to obtain a gel mixture, put the obtained gel mixture into a stainless steel autoclave lined with polytetrafluoroethylene, seal it and put it into an oven, carry out hydrothermal crystallization at 180 °C for 24 h, wash the obtained crystallization product with deionized water, dry at 80 °C for 10 h, and calcine at 500 °C for 6 h to obtain a hierarchical pore structure ZSM-5 molecular sieve catalyst.
[0052] Example 3
[0053] Mix 1 g of ZSM-5 seeds evenly with 0.5 mol / L nitric acid solution, stir at 20 °C for 20 h, wash with deionized water, dry at 80 °C for 20 h, and calcine at 500 °C for 2 h to obtain modified ZSM-5 seeds;
[0054] Sodium aluminate, tetraethyl orthosilicate, ammonium heptamolybdate and modified ZSM-5 seeds were mixed evenly according to a molar ratio of 5:100:10:10, stirred at 20 °C for 2 h to obtain a gel mixture. The obtained gel mixture was loaded into a stainless-steel autoclave with a polytetrafluoroethylene lining, sealed and then placed in an oven for hydrothermal crystallization at 180 °C for 36 h. The obtained crystallized product was washed with deionized water, dried at 100 °C for 10 h, and calcined at 500 °C for 4 h to obtain a ZSM-5 molecular sieve catalyst with a hierarchical pore structure.
[0055] Example 4
[0056] 2 g of ZSM-5 seeds were mixed evenly with 0.2 mol / L hydrochloric acid solution, stirred at 60 °C for 6 h, washed with deionized water, dried at 80 °C for 10 h, and calcined at 550 °C for 6 h to obtain modified ZSM-5 seeds;
[0057] Sodium aluminate, tetraethyl orthosilicate, ammonium heptamolybdate and modified ZSM-5 seeds were mixed evenly according to a molar ratio of 5:100:5:20, stirred at 20 °C for 2 h to obtain a gel mixture. The obtained gel mixture was loaded into a stainless-steel autoclave with a polytetrafluoroethylene lining, sealed and then placed in an oven for hydrothermal crystallization at 180 °C for 20 h. The obtained crystallized product was washed with deionized water, dried at 80 °C for 10 h, and calcined at 500 °C for 4 h to obtain a ZSM-5 molecular sieve catalyst with a hierarchical pore structure.
[0058] Example 5
[0059] 2 g of ZSM-5 seeds were mixed evenly with 0.2 mol / L hydrochloric acid solution, stirred at 20 °C for 20 h, washed with deionized water, dried at 80 °C for 10 h, and calcined at 500 °C for 2 h to obtain modified ZSM-5 seeds;
[0060] Sodium aluminate, tetraethyl orthosilicate, ammonium heptamolybdate and modified ZSM-5 seeds were mixed evenly according to a molar ratio of 5:200:5:10, stirred at 20 °C for 2 h to obtain a gel mixture. The obtained gel mixture was loaded into a stainless-steel autoclave with a polytetrafluoroethylene lining, sealed and then placed in an oven for hydrothermal crystallization at 180 °C for 48 h. The obtained crystallized product was washed with deionized water, dried at 80 °C for 10 h, and calcined at 550 °C for 8 h to obtain a ZSM-5 molecular sieve catalyst with a hierarchical pore structure.
[0061] Comparative Example 1
[0062] A batch of ZSM-5 molecular sieves (SiO2 / Al2O3 molar ratio is 100) was purchased from a molecular sieve manufacturer. The purchased ZSM-5 molecular sieves were impregnated isovolumetrically in a 0.3% ammonium heptamolybdate solution, dried at 120 °C for 2 h, and calcined at 600 °C for 8 h to obtain the CAT-1A catalyst.
[0063] Comparative Example 2
[0064] A batch of ZSM-5 molecular sieves (SiO2 / Al2O3 molar ratio is 100) was purchased from a conventional molecular sieve manufacturer. The purchased ZSM-5 molecular sieves were impregnated isovolumetrically in a 0.2% ammonium heptamolybdate solution, dried at 120 °C for 2 h, and calcined at 600 °C for 8 h to obtain the CAT-2A catalyst.
[0065] Test Example
[0066] The ZSM-5 molecular sieve catalyst obtained in Example 4 was characterized, and the results are shown as follows:
[0067] The X-ray diffraction patterns of the ZSM-5 molecular sieve catalyst and ZSM-5 seed crystals obtained in Example 4 are as Figure 1 shown. The characteristic peaks in the spectra indicate that the synthesized molecular sieve has a typical MFI structure, and compared with the ZSM-5 seed crystals, the crystallinity of the formed hierarchical pore ZSM-5 molecular sieve is significantly improved.
[0068] The scanning electron microscope photos of the ZSM-5 molecular sieve catalyst and ZSM-5 seed crystals obtained in Example 4 are as Figure 2 shown ( Figure 2 the scale bar in
[0069] is 100 nm). The surface of ZSM-5 has a high degree of rupture, while for the synthesized hierarchical pore ZSM-5 molecular sieve, its surface structure is repaired, which further proves that its relative crystallinity is improved. Figure 3 (a) and (b) shown. It can be seen from Figure 3 that the isotherm shows a hysteresis loop and there is an obvious mesoporous distribution at 4 nm, indicating the presence of a mesoporous structure, which proves that the synthesized ZSM-5 molecular sieve belongs to a hierarchical pore structure. After testing, the specific surface area of the ZSM-5 molecular sieve catalyst prepared in this example can reach 405 m 2 / g, the mesoporous pore volume is 0.25 cm 3 / g, and the average pore diameter reaches 3.7 nm, while the specific surface area of the ZSM-5 seed crystals is 284 m 2 / g, the mesoporous pore volume is 0.17 cm 3 / g, and the average pore diameter is 1.9 nm.
[0070] By subjecting the purchased ZSM-5 seeds and the hierarchical pore ZSM-5 molecular sieve catalyst obtained in Example 4 to the methane aromatization reaction after loading with ammonium heptamolybdate solution, the carbon deposition amount is as follows Figure 4 shown. The carbon deposition during the reaction of the hierarchical pore Mo / ZSM-5 molecular sieve is only 0.8%, which is much lower than the carbon deposition amount on the Mo / ZSM-5 seeds, indicating that this catalyst has excellent anti-carbon deposition performance.
[0071] The catalysts of the above Examples 1 to 5 and the comparative examples were used for the anaerobic aromatization reaction of methane, and their activities were tested. The results are shown in Table 1.
[0072] Table 1 Comparison of the reaction activities of the catalysts obtained in Examples 1 to 5 and Comparative Examples 1 and 2
[0073] Catalyst source Average methane conversion rate (%) Average selectivity to aromatics (%) Reaction time (h) CAT-1A Comparative Example 1 9 81 23 CAT-2A Comparative Example 2 7 72 21 CAT-1 Example 1 15 95 54 CAT-2 Example 2 17 94 62 CAT-3 Example 3 16 96 49 CAT-4 Example 4 19 97 65 CAT-5 Example 5 21 94 60
[0074] As can be seen from Table 1, compared with CAT-1 and CAT-2 prepared according to the present invention, the methane conversion rate, aromatic hydrocarbon selectivity and reaction stability of the conventionally prepared CAT-1A and CAT-2A are all lower than those of the molecular sieve catalysts prepared according to the present invention.
[0075] Although the above embodiments have described the present invention in detail, they are only a part of the embodiments of the present invention, not all of them. People can also obtain other embodiments without creative efforts based on these embodiments, and these embodiments all fall within the protection scope of the present invention.
Claims
1. A method for preparing a molecular sieve catalyst, characterized in that, Without using a template agent, including the following steps: Mix an aluminum source, a silicon source, a molybdenum-containing active component, and a modified molecular sieve seed, conduct hydrothermal crystallization, and obtain the molecular sieve catalyst after calcination; the modified molecular sieve seed is an acid-modified molecular sieve seed or a base-modified molecular sieve seed.
2. The preparation method according to claim 1, characterized in that, The base reagent used for the base modification is one or more of strong bases, weak bases, and basic salts; The acid reagent used for the acid modification is one or more of strong acids, weak acids, and acidic salts.
3. The preparation method according to claim 2, characterized in that, The concentrations of the base reagent and the acid reagent are independently 0.1 - 5.0 mol / L.
4. The preparation method according to claim 1, characterized in that, The molecular sieve seed is a zeolite molecular sieve seed.
5. The preparation method according to claim 1, characterized in that, The aluminum source includes one or several of sodium aluminate, alumina, boehmite, aluminum isopropoxide, and aluminum hydroxide; The silicon source includes one or several of silica sol, silicon dioxide, fumed silica, and tetraethyl orthosilicate; The molybdenum-containing active component is one or several of ammonium molybdate, sodium molybdate, and zinc molybdate.
6. The preparation method according to claim 1 or 5, characterized in that The molar ratio of the aluminum source, the silicon source, the molybdenum-containing active component, and the modified molecular sieve seed is 1 - 10:50 - 500:1 - 100:1 - 50.
7. The preparation method according to claim 1, characterized in that The temperature of the acid modification or base modification is 10 - 100 °C, and the time is 2 - 50 h.
8. The preparation method according to claim 1, wherein, The temperature of the hydrothermal crystallization is 100 - 200 °C, and the time is 6 - 120 h; The temperature of the calcination is 400 - 700 °C, and the time is 2 - 10 h.
9. The molecular sieve catalyst prepared by the preparation method according to any one of claims 1 to 8, characterized in that, The molecular sieve catalyst has a microporous-mesoporous hierarchical pore structure; the average pore diameter of the molecular sieve catalyst is 2 - 50 nm.
10. Use of the molecular sieve catalyst according to claim 9 in the catalytic non-oxidative aromatization reaction of light alkanes; the light alkanes are alkanes with 1 - 4 carbon atoms.