CN-121990587-A - Tungsten-containing multistage-pore ZSM-5 zeolite molecular sieve and preparation method thereof

Abstract

The invention discloses a tungsten-containing multistage-pore ZSM-5 zeolite molecular sieve and a preparation method thereof, wherein 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.

Inventors

• YANG GUIDONG
• YUE QIUDI
• GAO SHUYUAN

Assignees

• 西安交通大学

Dates

Publication Date

20260508

Application Date

20260303

Claims (10)

1. 1. The preparation method of the tungsten-containing multistage-pore ZSM-5 zeolite molecular sieve is characterized by comprising the following steps of: 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 multistage-pore ZSM-5 zeolite molecular sieve.
2. 2. The method for preparing a multistage pore ZSM-5 zeolite molecular sieve containing tungsten according to claim 1, wherein the silicon source is a mixture of one or more of tetraethyl orthosilicate, silica sol and water glass.
3. 3. The method for preparing a multistage pore ZSM-5 zeolite molecular sieve containing tungsten according to claim 1, wherein the aluminum source is a mixture of one or more of aluminum sulfate, aluminum nitrate, sodium metaaluminate and aluminum isopropoxide.
4. 4. The method for preparing a multistage pore ZSM-5 zeolite molecular sieve containing tungsten according to claim 1, wherein the tungsten source is a mixture of one or more of tungstic acid, sodium tungstate and ammonium metatungstate.
5. 5. The method for preparing a multistage pore ZSM-5 zeolite molecular sieve containing tungsten according to claim 1, wherein the additive is a mixture of one or more of tetramethylguanidine, urea, ammonium chloride and ammonium carbonate.
6. 6. The method for preparing a multistage pore ZSM-5 zeolite molecular sieve containing tungsten according to claim 1, wherein the seed crystal is ZSM-5 zeolite.
7. 7. The method for preparing a multistage pore ZSM-5 zeolite molecular sieve according to claim 1, wherein the molar ratio of silica in a silicon source, alumina in an aluminum source, tungsten trioxide in a tungsten source, sodium oxide, seed crystals, additives and water is 1:x:y:z:p:n:m, 0.02≤x≤0.04, 0≤y≤0.03, 0.1≤z≤0.2, 0≤p≤0.1, 0≤n≤0.4, 10≤m <30.
8. 8. The method for preparing a multistage pore ZSM-5 zeolite molecular sieve containing tungsten according to claim 1, wherein the crystallization temperature is 150 to 200 ℃; The crystallization time is 8 days to 20 days.
9. 9. The method for preparing the multistage pore ZSM-5 zeolite molecular sieve according to claim 1, wherein the process of mixing a silicon source, an aluminum source, a tungsten source, an additive, a seed crystal, sodium oxide and water to form a reaction system comprises the steps of mixing sodium oxide with the silicon source and the seed crystal, adding the tungsten source, the aluminum source, the water and the additive, and mixing to obtain the reaction system.
10. 10. The tungsten-containing multistage-pore ZSM-5 zeolite molecular sieve is characterized in that the tungsten-containing multistage-pore ZSM-5 zeolite molecular sieve is prepared based on the preparation method of the tungsten-containing multistage-pore ZSM-5 zeolite molecular sieve in any one of claims 1-9, the tungsten-containing multistage-pore ZSM-5 zeolite molecular sieve has a mesoporous structure formed by stacking zeolite molecular sieve grains, the mesoporous volume is greater than or equal to 0.2 cm 3 /g, the specific surface area is greater than 350 m 2 /g, wherein the primary particle size of the tungsten-containing multistage-pore ZSM-5 zeolite molecular sieve is 50-200nm, and the secondary stacking particle size is 20-50 mu m.

Description

Tungsten-containing multistage-pore ZSM-5 zeolite molecular sieve and preparation method thereof Technical Field The invention belongs to the technical field of zeolite molecular sieve synthesis, and relates to a tungsten-containing multistage pore ZSM-5 zeolite molecular sieve and a preparation method thereof. Background Zeolite molecular sieve is a crystalline inorganic aluminosilicate framework material which is typically characterized by a crystalline structure having uniformly sized microporous channels and aligned voids. ZSM-5 zeolite molecular sieve is widely used as solid acid catalyst in petrochemical industry, coal chemical industry and other fields due to its unique pore structure, good thermal stability, suitable adjustable acid center density and excellent shape selective catalytic effect. Meanwhile, the ZSM-5 zeolite molecular sieve is an excellent carrier of metal ions or metal oxides with catalytic activity, the ZSM-5 zeolite molecular sieve loaded with iron, tungsten, manganese and other catalysts show excellent catalytic performance in the reactions of olefin catalytic cracking, hydrocarbon aromatization and the like, CN202411461118.4 provides a zinc-modified multistage pore three-dimensional nano-plate ZSM-5 molecular sieve, the catalyst has higher n-octane aromatization performance, and can inhibit further aromatization on the surface of the catalyst, the n-octane conversion rate is over 99 percent, and the BTX selectivity is 71 percent. ZSM-5 zeolite molecular sieve is a mesoporous material with 10-membered ring pore channels, and the diffusion of reactants is limited due to the smaller pore channel size, so that the catalytic reaction efficiency is reduced to a certain extent. Meanwhile, the ZSM-5 zeolite molecular sieve needs one or more metals to be loaded when the acid property is regulated, and the loading mode is influenced by the metal loading utilization rate and the process difficulty. In order to solve the problem of diffusion limitation of ZSM-5 zeolite molecular sieves caused by smaller pore sizes, a multistage pore structure is generally introduced into a zeolite molecular sieve system, so that the zeolite molecular sieve system has both the substance conveying performance of a mesoporous zeolite molecular sieve and the catalytic property of a microporous zeolite molecular sieve. Currently, the synthesis methods of the hierarchical pore ZSM-5 zeolite molecular sieve mainly comprise a post-treatment method and a direct synthesis method. The post-treatment method comprises an acid dealumination method and an alkali desilication method. The post-treatment method can selectively produce mesopores and even macropores, but inevitably causes the loss of zeolite crystallinity, and has the problem of waste liquid treatment. Direct synthesis generally requires the addition of a second templating agent (carbon nanoparticles, nanotubes, surfactants, cationic polymers, etc.) to interact with the silicon source aluminum source to introduce mesopores. However, the template agent has high cost and high experimental condition requirement, and limits industrial application. For loading metals on zeolite molecular sieves, the current preparation methods are largely divided into post-treatment methods and one-step synthesis methods. Post synthesis methods mainly include impregnation and ion exchange. The impregnation method is to adsorb or deposit the metal precursor on the zeolite surface and in the pore canal by impregnation containing metal ions, and then to convert the metal precursor into target metal species by roasting. However, impregnation methods can suffer from particle agglomeration and channel blockage. The ion exchange method realizes the loading by the replacement of exchangeable cations outside the zeolite framework and metal cations in the solution, but the ion exchange method has low metal loading amount and complex process. The one-step process is typically carried out by introducing the metal salt or organometallic precursor directly into the reaction gel in a conventional hydrothermal system. The method synchronously introduces metal in the zeolite crystallization process, so that metal ions are directly embedded into a framework or uniformly dispersed in a pore canal to form a metal-zeolite complex with uniform structure. However, one-step synthesis still faces challenges, one of which is the need for specific synthesis formulations that render the zeolite structure unaffected by the introduction of metal ions. Secondly, the problem that metal cations are easy to quickly precipitate in an alkaline zeolite precursor solution to prevent the metal cations from entering zeolite pore channels needs to be solved. Therefore, under the condition of not adding a second template agent, the one-step hydrothermal direct synthesis of the multistage pore ZSM-5 zeolite molecular sieve containing tungsten has great significance, but the synthesis is more challenging, and related patent r