A kind of preparation method of hierarchical porous zsm-5 nano-aggregate

A technology of ZSM-5 and agglomerates, which is applied in the direction of crystalline aluminosilicate zeolite, borocarbane silicone crystalline aluminosilicate zeolite, etc., can solve the problems of increased energy consumption, large zeolite size, and poor uniformity. Achieve the effects of reducing production energy consumption, reducing the generation of miscellaneous crystals, and accelerating the growth rate

Active Publication Date: 2020-08-21
DALIAN UNIV OF TECH
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Problems solved by technology

Chinese patent CN104760974A synthesizes a multi-level pore structure ZSM-5 aggregate zeolite with open channels in the next step of the template-free system, but the size of the zeolite prepared by the system without adding any alkali metal salt is relatively large, and the amount of seed crystals added is 0.5 The size of zeolite is about 2 μm in wt%, which is not conducive to mass transfer to a certain extent, and the uniformity is poor; the one-step high-temperature crystallization method increases the energy consumption demand
However, there is no report on the use of potassium dihydrogen phosphate as an alkali metal salt to regulate the size and uniformity of aggregated zeolites.

Method used

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  • A kind of preparation method of hierarchical porous zsm-5 nano-aggregate
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  • A kind of preparation method of hierarchical porous zsm-5 nano-aggregate

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Effect test

Embodiment 1

[0030] (1) Preparation of MFI nanostructure microcrystalline liquid

[0031] Mole ratio TPAOH:TEOS:H 2 O: EtOH=7.5:28:360:1000, 24.7mlTPAOH, 4mlH 2 O, 23.6ml EtOH and 25.8ml TEOS were mixed uniformly at room temperature; then loaded into a polytetrafluoroethylene-lined kettle, statically crystallized in an oven at 80°C for 3 days, cooled to room temperature, and MFI microcrystalline liquid with a size of no more than 80nm was obtained.

[0032] (2) Preparation of hierarchically porous ZSM-5 aggregates in a template-free system

[0033] According to the molar ratio of alkali source, silicon source, aluminum source, potassium dihydrogen phosphate and water 9.5:100:2.86:10.8:2126, 0.43g sodium metaaluminate, 0.47g sodium hydroxide, 1.34g potassium dihydrogen phosphate, Added into 24.3ml of deionized water, mechanically stirred at room temperature for 30min to a clear state; then added 15.4ml of silica sol, stirred at room temperature for 30min, added 0.5wt% microcrystalline liq...

Embodiment 2

[0035] (1) The preparation method of the MFI nanostructure microcrystalline liquid is the same as that in Example 1.

[0036](2) According to the molar ratio of alkali source, silicon source, aluminum source, potassium dihydrogen phosphate and water 9.5:100:2.86:21.6:2126, 0.43g sodium metaaluminate, 0.47g sodium hydroxide, 2.68g diphosphate Potassium hydrogen was added to 24.3ml of deionized water, stirred mechanically at room temperature for 30min to a clear state; then added 15.4ml of silica sol, stirred at room temperature for 30min, then added 0.5% wt of the seed liquid synthesized in step (1), and aged for 1h to Gel state; put into polytetrafluoroethylene-lined kettle; static crystallization at 60°C for 4 hours, then static crystallization at 170°C for 8 hours; cool to room temperature, centrifuge, wash until neutral; then dry in an oven at 100°C After 6h, hierarchical porous ZSM-5 nanoaggregates were obtained. The yield of the synthesized sample is 94.4%; the aggregate...

Embodiment 3

[0038] (1) Preparation of MFI nanostructure microcrystalline liquid

[0039] Mole ratio TPAOH:TEOS:H 2 O: EtOH=7.5:28:360:1000, 24.7mlTPAOH, 4mlH 2 O, 23.6ml of EtOH and 25.8ml of TEOS were mixed uniformly at room temperature; then loaded into a polytetrafluoroethylene-lined kettle, statically crystallized in an oven at 60°C for 5 days, cooled to room temperature, and MFI microcrystalline liquid with a size of no more than 80nm was obtained.

[0040] (2) According to the molar ratio of alkali source, silicon source, aluminum source, potassium dihydrogen phosphate and water 12:100:2.5:32.4:1063, 0.38g sodium metaaluminate, 0.59g sodium hydroxide, 4.02g diphosphate Potassium hydrogen was added to 12.1ml of deionized water, stirred mechanically at room temperature for 30min to a clear state; then added 15.4ml of silica sol, stirred at room temperature for 30min, then added 0.5wt% of the seed liquid synthesized in step (1), and aged for 1h to Gel state; put into a polytetrafluor...

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Abstract

The invention provides a preparation method of a hierarchical pore ZSM-5 nanometer aggregate. The method comprises the specific steps that alkali metal salt is added into a system formed by a siliconsource, an aluminum source and an alkali source at first; then, a small amount of nano-crystalline liquid is added into the system to form a gel state; finally, a low-temperature nucleation-high-temperature crystallization two-step temperature varying crystallization strategy is adopted for performing crystallization synthesis, and the hierarchical pore ZSM-5 nanometer aggregate similar to a hedgehog shape is obtained. By introducing the alkali metal salt, the problem that current most aggregate zeolites are not uniform is solved, and the whole zeolite size and the nanometer primary particle size are both controllable; due to the two-step temperature varying strategy, the zeolite crystallization time is greatly shortened; under a template-free system, a small amount of nanometer microcrystalline liquid is added, and the theory for green chemical synthesis is met. Accordingly, the method has the advantages of being easy to operate, low in energy dissipation, environmentally friendly andthe like, and has the good industrial application value.

Description

technical field [0001] The invention provides a method for preparing multi-level porous ZSM-5 nano-aggregates with an alkali metal salt-free template system, which belongs to the field of multi-level porous molecular sieves and catalysis science. Background technique [0002] The multi-level pore ZSM-5 molecular sieve combines the strong acidity, hydrothermal stability of microporous molecular sieves and the pore size advantages of mesoporous molecular sieves, and has become a hot research topic in the fields of catalysis, adsorption, and separation. [0003] The current methods for synthesizing hierarchically porous ZSM-5 molecular sieves mainly include template method, post-treatment method, and template-free method. The template method is further divided into hard template method and soft template method [ZhangY, Han X, Che S. Synthesis of hierarchical MFI zeolites with a micro-macroporous core@mesoporous shell structure [J]. Chemical Communications, 2019, 55, 810]. Chin...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C01B39/40
Inventor 张雄福赵国龙刘海鸥
Owner DALIAN UNIV OF TECH
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