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Synthesis method of nano small-grain ZSM-22 molecular sieve

A technology for ZSM-22 and synthesis methods, applied in the direction of molecular sieves and base exchange compounds, nanotechnology, chemical instruments and methods, etc., can solve the problems of high production cost and difficulty in industrial application of ZSM-22 molecular sieves, and achieve good application prospects, Improved mass transfer and diffusion performance, easy operation

Active Publication Date: 2021-08-10
FUZHOU UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0008] In order to solve the problems of high production cost and difficult industrial application of ZSM-22 molecular sieve, the present invention provides a method for synthesizing ZSM-22 molecular sieve with nanometer small grains, which removes the natural diatomite by thermal activation and weak acid treatment. Skeleton aluminum, to obtain dealuminated diatomite that meets the ratio of silicon to aluminum; obtain a highly dispersed and uniform silicon source by alkaline leaching of dealuminated diatomite; retain the skeleton structure and pore structure of diatomite to grow in situ The mesoporous specific surface area of ​​the product can be enlarged by means of the method; the use of organic template can be avoided and the ZSM-22 molecular sieve with high crystallinity and high hydrothermal stability can be obtained only by introducing seeds

Method used

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  • Synthesis method of nano small-grain ZSM-22 molecular sieve
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  • Synthesis method of nano small-grain ZSM-22 molecular sieve

Examples

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Embodiment 1

[0032] Example 1: Preparation of small-grain ZSM-22 molecular sieve based on in-situ crystallization of dealuminated diatomite

[0033] Get 2.4 g dealuminated diatomite and mix with 43.8 g deionized water, add 0.54 g KOH, at 50 o After leaching at C for 8 h, separate by suction filtration, and temporarily place the solid phase. Commercial ZSM-22 molecular sieves were added to the liquid phase as seeds, and the amount of seeds added was related to the SiO 2 The mass ratio is 0.1, moved into the water bath 80 o C aging for 8 h. After mixing the solid phase and the aged liquid phase evenly, an initial gel containing seeds is obtained, and its gel composition is 100SiO 2 :Al 2 o 3 :3600H 2 O:20KOH (molar ratio). After stirring for 30 min, it was transferred to a polytetrafluoroethylene-lined reactor for dynamic crystallization at a rate of 400 rpm, and the crystallization temperature was 150 o C, the crystallization time is 42 h. After the crystallization was finished, th...

Embodiment 2

[0035] Example 2: Preparation of small crystal ZSM-22 molecular sieve based on in situ crystallization of dealuminated diatomite. The steps are the same as in Example 1, only some parameters are modulated, as follows:

[0036] Get 2.4 g dealuminated diatomite and mix with 43.8 g deionized water, add 0.27 g KOH, at 30 o After leaching at C for 5 h, separate by suction filtration, and temporarily place the solid phase. Commercial ZSM-22 molecular sieves were added to the liquid phase as seeds, and the amount of seeds added was related to the SiO 2 The mass ratio is 0.02, moved into the water bath 90 o C for 12 h. After mixing the solid phase and the aged liquid phase evenly, an initial gel containing seeds is obtained, and its gel composition is 100SiO 2 :Al 2 o 3 :3600H 2 O:10KOH (molar ratio). After stirring for 30 min, it was transferred to a reaction kettle with a polytetrafluoroethylene liner for dynamic crystallization at a rate of 400 rpm, and the crystallization ...

Embodiment 3

[0038] Example 3: Preparation of ZSM-22 molecular sieve with small crystals based on dealuminated diatomite in situ crystallization under low temperature conditions. The steps are the same as in Example 1, only some parameters are modulated, as follows:

[0039] Adjust the crystallization temperature to 120 o C, the crystallization time is 48 h.

[0040] The synthesized products are ZSM-22 molecular sieves with a particle size width of 50 nm and amorphous silicon source.

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Abstract

The invention belongs to the field of synthesis of molecular sieves, and relates to a synthesis method of a nano small-grain ZSM-22 molecular sieve. According to the method, natural diatomite is used as all silicon sources and aluminum sources required for synthesizing the molecular sieve, and in-situ crystallization is carried out under the condition of no template to obtain the nano small-grain ZSM-22 molecular sieve. The composition and skeleton of the diatomite are fully utilized, the original pore structure of the diatomite is reserved in the synthesis process of the molecular sieve, the silicon-aluminum ratio and grain size of the product molecular sieve are regulated and controlled by controlling the silicon-aluminum content of the diatomite and the composition of the initial gel, and the high-crystallinity nano small-grain ZSM-22 molecular sieve with a large external specific surface area and an adjustable silica-alumina ratio is synthesized. The method has the advantages of simple and efficient synthesis process, environmental protection, low cost and great industrialization prospect.

Description

technical field [0001] The invention belongs to the field of molecular sieve synthesis, and relates to a method for synthesizing ZSM-22 molecular sieve with nanometer small grains. Background technique [0002] ZSM-22 molecular sieve is a microporous high-silicon-aluminum ratio molecular sieve developed by Mobil in the 1980s. Its crystal is orthorhombic in the orthorhombic system. The six-membered rings are connected along the Y axis, and the main channel is a one-dimensional channel structure of ten-membered rings without crossing channels, which has a typical TON structure, and the main channel pore size is 0.45 nm×0.55 nm. Compared with other ten-membered ring molecular sieves (such as ZSM-5, ZSM-11, ZSM-35), ZSM-22 molecular sieve has smaller pore diameter, and its advantages in adsorption reaction mechanism make it an excellent catalyst for skeletal isomerization reaction . Because of this unique pore structure, medium-strength surface acidity, excellent catalytic act...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B39/46B82Y40/00
CPCC01B39/46B82Y40/00C01P2004/51C01P2006/12C01P2004/03C01P2002/72C01P2006/17Y02P20/52
Inventor 岳源源叶颖辉鲍晓军王婵王廷海朱海波王鹏照
Owner FUZHOU UNIV
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