Rapid and economic synthesis method of ultrathin MFI molecular sieve membrane

A synthesis method and molecular sieve technology, applied in separation methods, chemical instruments and methods, membrane technology, etc., can solve the problem of difficulty in preparing ultra-thin molecular sieve membranes with raw material utilization, and achieve lower synthesis costs, high separation performance, and improved utilization. Effect

Active Publication Date: 2020-04-17
SHANGHAI UNIV OF ENG SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0005] The purpose of the present invention is to provide a fast and economical synthesis method of an ultra-thin MFI molecular sieve membrane in order to overcome the defects in th...

Method used

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  • Rapid and economic synthesis method of ultrathin MFI molecular sieve membrane
  • Rapid and economic synthesis method of ultrathin MFI molecular sieve membrane
  • Rapid and economic synthesis method of ultrathin MFI molecular sieve membrane

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preparation example Construction

[0031] A fast and economical synthesis method of ultra-thin MFI molecular sieve membrane, the seed crystal is loaded on the porous ceramic carrier, after the molecular sieve membrane synthesis mother liquor is impregnated, there is only a small amount of liquid (molecular sieve membrane synthesis mother liquor, and no direct contact with the membrane tube) Crystallization in a crystallization kettle, the amorphous particles in the seed layer are converted into molecular sieve crystals at fixed points, and finally a continuous molecular sieve membrane is formed. The thickness of the prepared MFI molecular sieve membrane can be between 100 and 2000 nanometers, and it has extremely high separation performance. It specifically includes the following steps:

[0032](1) The all-silicon Silicalite-1 molecular sieve crystal seed is uniformly coated on the porous carrier by methods such as brushing, dipping, spraying or spin coating, and the scale of the all-silicon Silicalite-1 molecul...

Embodiment 1

[0038] In this example, the Silicalite-1 molecular sieve membrane is synthesized by heating in a traditional oven, and the specific steps are as follows:

[0039] Step 1: Synthetic formula of all-silicon Silicalite-1 molecular sieve: 25SiO 2 :9TPAOH:360H 2 O: 100 EtOH (TPAOH: tetrapropylammonium hydroxide). Mix ethyl orthosilicate and tetrapropylammonium hydroxide, stir for 4 hours, remove excess water and ethanol in an oven at 80 degrees Celsius, then add hydrofluoric acid, and stir to obtain a synthetic mother liquor. Then crystallize at 453K for 24 hours to obtain all-silicon Silicalite-1 molecular sieve. The crystal diameter is less than 100 nanometers and can be used directly. It is also possible to use large-grained Silicalite-1 molecular sieves, and grind its crystals to below 200 nanometers after ball milling. Disperse the ball-milled seed crystals in water to form a 0.1-0.4 wt% seed crystal dip coating solution.

[0040] Step 2, select a porous ceramic tube with ...

Embodiment 2

[0050] The difference from Example 1 is that in step 3, the molecular sieve membrane synthesis mother liquor formula is 1SiO 2 :0.576EDA:0.36TPAOH:50H 2 O, all the other steps are identical with embodiment 1.

[0051] The surface and section of gained Silicalite-1 molecular sieve membrane are as follows figure 2 shown, from figure 2 It can be seen that the surface of the carrier is completely covered by Silicalite-1 crystals, and the crosslinking between the crystals is perfect (see figure a); the thickness of the film is relatively uniform, about 0.74 micron nm (see figure b).

[0052] The Silicalite-1 molecular sieve membrane tubes for CO 2 / CH 4 Gas separation test results, at 0.2MPa, its CO 2 The average value of the permeability is 49×10 -7 mol / (m 2 s Pa), CO 2 / CH 4 The average separation selectivity is 7.

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Abstract

The invention relates to a rapid and economical synthesis method of an ultrathin MFI molecular sieve membrane. The method comprises the following steps: loading a seed crystal on a porous ceramic carrier, dipping in a molecular sieve membrane synthesis mother liquor, crystallizing in a crystallization kettle with only a small amount of liquid (the molecular sieve membrane synthesis mother liquor is not directly contacted with a membrane tube), and finally forming the continuous molecular sieve membrane. Compared with the prior art, the method has the following advantages: the thickness of thesynthesized ultrathin MFI molecular sieve membrane is directly related to the thickness of the seed crystal layer and can be controlled to be 200-2000 nm, so that the mass transfer resistance is greatly reduced, and the permeability is improved; and a large amount of the synthesis mother liquor required by traditional hydrothermal synthesis is avoided, the utilization rate of raw materials is greatly increased, the synthesis belongs to atom economic synthesis, the synthesis speed of the molecular sieve membrane is greatly increased, the molecular sieve membrane can be synthesized very quicklyeven at a low temperature, and the synthesis efficiency is high. The method is also applicable to synthesis of other molecular sieve membranes.

Description

technical field [0001] The invention relates to the field of molecular sieve synthesis, in particular to an economical synthesis method for rapidly preparing ultra-thin MFI molecular sieve membranes under mild conditions. Background technique [0002] Inorganic molecular sieve membrane is obtained by preparing a layer of continuous, dense and uniform molecular sieve on a porous carrier. Due to the advantages of uniform pore size, high temperature resistance, chemical solvent resistance and ion exchange, inorganic molecular sieve membranes have great application potential in the fields of membrane catalytic reaction, gas separation, liquid pervaporation separation and environmental protection. For example, in CO 2 In the field of removal, because the membrane separation device has the advantages of low energy consumption, continuous operation, low equipment investment, small volume, and easy maintenance, it is very suitable for high CO 2 The harsh separation environment of ...

Claims

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Application Information

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IPC IPC(8): B01D71/02B01D67/00B01D69/02B01D53/22
CPCB01D71/028B01D67/0039B01D67/0051B01D69/02B01D53/228Y02P20/151
Inventor 张延风徐宁王明全张野
Owner SHANGHAI UNIV OF ENG SCI
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