Preparation method of stepped hole heteroatom M-Beta molecular sieve

A technology of heteroatom and molecular sieve, which is applied in the field of preparation of heteroatom M-Beta nanocrystals, can solve the problems of reducing alkalinity of crystallization system, environmental hazards, autoclave pressure, etc., and achieves the improvement of nucleation efficiency and crystallization efficiency. The effect of cost reduction and synthesis time reduction

Pending Publication Date: 2020-07-24
FUZHOU UNIV
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Problems solved by technology

However, the presence of aluminum in the synthesis system will not only preempt the growth position of heteroatoms, but also make the acidity of Beta zeolite too strong, thereby reducing the selectivity of some products (D.P.Serrano, Micropor.Mesopor.Mater.200,146,35; J.L. Zhang, Chem. Eng. J., 2016, 291, 82)
In order to make up for the defects of aluminum, Y.Naraki, H.Kessler (Y.Naraki,,Adv.Porous Mater.,2016,2,125; H.Kessler Stud.Surf.Sci.Catal.1994,85,75) et al. The introduction of fluorine-containing crystallization aids into the hydrothermal system, but the introduction of HF significantly reduces the alkalinity of the crystallization system, slows down the mass diffusion and nucleation rate in the mass transfer system, and easily forms large-grained zeolites
Secondly, as a highly corrosive and high-risk pollutant, HF will cause great harm to the environment with the large discharge of crystallization liquid.
[0006] To sum up, both the one-step hydrothermal synthesis method and the secondary isomorphic substitution method belong to the category of hydrothermal crystallization, and the inherent disadvantages of hydrothermal synthesis, such as large discharge of crystallization liquid, waste of nutrients, Excessive crystallization time, excessive template consumption, low single-pot yield, high pot pressure, etc. are unavoidable (L.M.Ren, J.Am.Chem.Soc., 2012,134,15173), therefore, the development A new method for efficient, green, and simple-step heteroatom zeolites is particularly important

Method used

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  • Preparation method of stepped hole heteroatom M-Beta molecular sieve
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  • Preparation method of stepped hole heteroatom M-Beta molecular sieve

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preparation example Construction

[0027] The present invention provides a kind of preparation method of step hole heteroatom M-Beta molecular sieve, it is characterized in that, the method comprises the following steps:

[0028] 1) Silicon source is SiO 2 In terms of, heteroatom metals are in terms of element M, and alkali sources are in terms of OH －According to the molar ratio of silicon source: heteroatom metal: alkali source: template agent: water = 1:0~0.07:0.01~0.8:0.05~0.5:20~80, fully mix, and then add 0.001% of the mass of silicon source ~10% pure silicon seed crystals, aged at 20-80°C for 0.5-2 hours, evaporated the aged hydrogel in an oil bath at 50-100°C for 12-48 hours to obtain templated and seeded xerogels;

[0029] 2) Grind the xerogel obtained in step 1), place it in the kettle and the small inner liner respectively according to the water:dry powder mass ratio of 0.01-1:1, and crystallize at 120-170°C for 20-96 hours, the obtained The product was ion-exchanged in 1 mol / L ammonium salt solut...

Embodiment 1

[0048] This example is used to illustrate a preparation method of a heteroatom Ti-Beta molecular sieve.

[0049] First, the silicon source, titanium source, alkali source, template agent, and water are prepared according to the formula of silica: titanocene dichloride: NaOH: TEAOH: H 2 The molar ratio of O=1:0.015:0.1:0.15:50 is fully mixed, then a seed crystal equivalent to 10% of the mass of the silicon source is added, and aged at a temperature of 30° C. for 0.5 hour. The aged hydrogel was evaporated in an oil bath at 60°C for 48 hours to obtain a templated and seeded xerogel. Grind the obtained xerogel until there is no grain feeling, take 10g and put it in a small inner liner, then put it into a crystallization kettle filled with 1g of water, seal the kettle, and crystallize at 145°C for 48 hours, the obtained product Ion exchanged in 1mol / L ammonium nitrate solution for 2 hours, washed to neutral and dried, then calcined at 550°C for 6 hours to obtain product a.

Embodiment 2

[0051] This example is used to illustrate a preparation method of a heteroatom Fe-Beta molecular sieve.

[0052] First, the silicon source, iron source, alkali source, template agent, and water are mixed according to the formula of silica: ferric ammonium citrate: NaOH: TEAOH: H 2 The molar ratio of O=1:0.028:0.16:0.1:40 is fully mixed, then a seed crystal equivalent to 1% of the mass of the silicon source is added, and aged at a temperature of 30° C. for 0.5 hour. The aged hydrogel was evaporated in an oil bath at 70°C for 24 hours to obtain a templated and seeded xerogel. Grind the obtained xerogel until there is no grain feeling, take 10g and put it in a small inner liner, then put it into a crystallization kettle filled with 5g of water, seal the kettle, and crystallize at 145°C for 48 hours, the obtained product Ion exchanged in 1mol / L ammonium nitrate solution for 2 hours, washed to neutral and dried, then calcined at 550°C for 6 hours to obtain product b.

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Abstract

The invention provides a preparation method of a stepped hole heteroatom M-Beta molecular sieve. Compared with an existing synthesis method, the method has the advantages that the M-Beta molecular sieve can be directly synthesized through a one-step steam-assisted method, and the inherent defects of traditional hydrothermal synthesis are overcome. Compared with the existing M-Beta synthesis method, the method has the advantages that the M-Beta molecular sieve with a regular morphology and a stepped pore structure can be synthesized without a nuclear promoter aluminum and a high-corrosivity crystallization aid hydrofluoric acid; the synthesis time is reduced to 48 hours, the steps are simple, and the energy consumption can be effectively reduced; little crystallization liquid is generated so that the pollution problem of a large amount of crystallization waste liquid can be effectively avoided; meanwhile, the problem that a large amount of waste acid is discharged due to the fact that strong acid must be used for pretreatment in a traditional secondary isomorphous substitution method and an aluminum-containing one-step synthesis method is solved.

Description

technical field [0001] The invention relates to a preparation method for synthesizing framework heteroatom M-Beta molecular sieves, specifically a preparation method for synthesizing [Al, F]-Free heteroatom M-Beta nanocrystals in one step by steam-assisted conversion. Background technique [0002] Beta molecular sieve is the only molecular sieve with three-dimensional intersecting channels of twelve-membered rings, which has unique pore structure, acidity and good hydrothermal stability. The traditional Beta molecular sieve is a silica-alumina zeolite, but only relying on the traditional Al-Beta zeolite cannot greatly improve the application field of the BEA structure. The introduction of different transition metals (Ti, Fe, Co, Ga, etc.) into the zeolite framework can endow the silicon framework with separated, well-dispersed, and diverse catalytic active centers. The special pore structure of zeolite provides a suitable living space for these metal atoms, so that it has b...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B37/00C01B39/08C01B39/04
CPCC01B37/005C01B39/04C01B39/085C01B39/087C01B39/082C01B39/08C01P2002/72C01P2002/84C01P2004/04
Inventor 陈晓晖罗玉莹胡晖黄清明
Owner FUZHOU UNIV
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