Nanometer flaky MFI molecular sieve and preparation method thereof

A nano-sheet, molecular sieve technology, applied in the field of molecular sieves, can solve problems such as lack of crystal face selectivity, and achieve the effects of low production cost, uniform heating and uniform particle size

Active Publication Date: 2022-04-22
FUDAN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The traditional nano-zeolite synthesis method is generally a low-temperature (below 100°C) hydrothermal treatment for several days or even a few weeks, and the stable product is generally nano-spherical crystal particles, lacking crystal face selectivity

Method used

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  • Nanometer flaky MFI molecular sieve and preparation method thereof
  • Nanometer flaky MFI molecular sieve and preparation method thereof
  • Nanometer flaky MFI molecular sieve and preparation method thereof

Examples

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preparation example Construction

[0033] The present invention provides a kind of preparation method of nano sheet MFI molecular sieve, comprises the following steps:

[0034] Mix the silicon source, tetrapropylammonium hydroxide and water, conduct microwave heat treatment, and then dialysis and purify to obtain the MFI crystalline solution;

[0035] The MFI crystalline solution is subjected to hydrothermal treatment to obtain nanosheet MFI molecular sieves.

[0036] In the present invention, unless otherwise specified, all raw material components are commercially available products well known to those skilled in the art.

[0037] The invention mixes the silicon source, tetrapropylammonium hydroxide and water, conducts microwave heat treatment, and then dialysis and purifies to obtain the MFI crystalline solution.

[0038] In the present invention, the silicon source preferably includes one or more of tetraethyl orthosilicate, silica sol and white carbon black, more preferably tetraethyl orthosilicate or sili...

Embodiment 1

[0055] (1) tetrapropyl ammonium hydroxide is dissolved in water and is mixed with the tetrapropyl ammonium hydroxide aqueous solution that concentration is 20wt%; 3g tetraethyl orthosilicate is dissolved in the 6.1686g tetrapropyl ammonium hydroxide aqueous solution, in Stir and age at room temperature and 150 rpm for 24 hours, then transfer to a microwave reactor, first heat-treat with low-temperature microwave at 90°C for 90 minutes, and then heat-treat with high-temperature microwave at 130°C for 50 minutes to obtain a mixed solution of MFI zeolite. The MFI zeolite mixed solution was transferred to a cellulose semi-permeable membrane with a molecular weight cut-off of 3.5kDa, then soaked in 1L of tetrapropylammonium hydroxide aqueous solution with a concentration of 6mmol / L, purified by dialysis at room temperature and 30rpm for 24h, and then Place in deionized water for dialysis purification, and replace the deionized water every 12 hours until the pH of the dialyzed fluid ...

Embodiment 2

[0061] According to the method of Example 1, the nano-flaky MFI molecular sieve is prepared, and the difference from Example 1 is only that in step (2), the pH of the MFI crystallization solution is adjusted to 11.41 by using an aqueous sodium hydroxide solution with a concentration of 1mol / L. , and then placed in a hydrothermal reaction kettle, the crystals were hydrothermally treated in a constant temperature oven for 18 hours; the centrifugal speed was 15000 rpm, and the centrifugal time was 5 minutes.

[0062] Figure 4 Scanning electron microscope image of the nanosheet MFI molecular sieve prepared for this example. Depend on Figure 4 It can be seen that the length × width × thickness of the nano-flaky MFI molecular sieve crystal obtained in this example is 160nm × 160nm × 80nm, which is a nano-flaky MFI molecular sieve crystal in the short b-axis direction with high crystal plane selectivity, and has good size uniformity .

[0063] Figure 5 Transmission electron mi...

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Abstract

The invention provides a nanosheet-shaped MFI molecular sieve and a preparation method thereof, and relates to the technical field of molecular sieves. The preparation method comprises the following steps: mixing a silicon source, tetrapropylammonium hydroxide and water, carrying out microwave heat treatment, and dialyzing and purifying to obtain an MFI crystallite solution; and carrying out hydrothermal treatment on the MFI crystallite solution to obtain the nanosheet-shaped MFI molecular sieve. The microwave heating assisted synthesis method has the advantages of fast reaction and uniform heating, and can efficiently synthesize the MFI zeolite crystallite with a uniform structure; the MFI crystallite molecular sieve with high purity and uniform structure is obtained through dialysis and purification, the MFI crystallite molecular sieve is used as a raw material to facilitate the generation of the nanosheet-shaped MFI molecular sieve with stable morphology, and the nanosheet-shaped MFI molecular sieve with uniform particle size, high purity and uniform structure is obtained. Moreover, the preparation method provided by the invention is simple to operate and simple in process, and the nanosheet zeolite material with the size required by practical application can be efficiently customized.

Description

technical field [0001] The invention relates to the technical field of molecular sieves, in particular to a nanosheet MFI molecular sieve and a preparation method thereof. Background technique [0002] Nano zeolite generally refers to zeolite crystals with a particle size of several nanometers to hundreds of nanometers, which have the same regular structure and micropore channels as traditional zeolite molecular sieves (with a size between 0.5 and 10 μm). The specific surface area and significantly shortened pore channels greatly improve the mass transfer and heat transfer efficiency of zeolite and the exposure degree of active centers in the process of adsorption and catalysis, thereby improving the adsorption and catalytic performance of zeolite. [0003] The special crystal plane orientation of nano-zeolites corresponds to three-dimensional channels with different average lengths, which endows nano-zeolites with specific diffusion advantages. For example, nano-sheet MFI m...

Claims

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Application Information

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IPC IPC(8): C01B39/04C01B39/48B82Y30/00B82Y40/00
CPCC01B39/04C01B39/48B82Y30/00B82Y40/00C01P2004/62C01P2004/64C01P2004/20C01P2004/52C01P2004/03C01P2004/04C01P2002/72
Inventor 张亚红盛治政唐颐杜可高嵝李贺谭智超王舒琪
Owner FUDAN UNIV
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