Ultrathin molecular sieve membrane and preparation method thereof

A molecular sieve, ultra-thin technology, applied in the direction of crystalline aluminosilicate zeolite, etc., can solve the problems of unfavorable commercial application of molecular sieve membrane, large mass transfer resistance, low permeability, etc., to avoid high temperature roasting to remove template agent, reduce transfer Mass resistance, improve the effect of permeability

Active Publication Date: 2021-05-04
SHANGHAI UNIV OF ENG SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The traditional hydrothermal synthesis method to prepare molecular sieve membranes has the advantages of simple methods, but the thickness of the prepared membranes is usually 2-10 microns, resulting in large mass transfer resistance and low permeability, which is not conducive to the commercial application of molecular sieve membranes

Method used

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  • Ultrathin molecular sieve membrane and preparation method thereof
  • Ultrathin molecular sieve membrane and preparation method thereof
  • Ultrathin molecular sieve membrane and preparation method thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0035] In this example, an ultra-thin MFI molecular sieve membrane is synthesized by heating in a traditional oven, and the specific steps are as follows:

[0036] Step 1: Tetrapropylammonium hydroxide was mixed in deionized water, then added tetraethyl orthosilicate, stirred for 4 hours to obtain the seed crystal reaction solution, and the molar ratio of the reaction solution was: SiO 2 :TPAOH (tetrapropylammonium hydroxide): H 2 O:EtOH=25:9:360:100, hydrothermal crystallization at 120°C for 24 hours to obtain all-silicon MFI molecular sieve seed crystals, and obtain nano-scale all-silicon MFI molecular sieve seed crystals (also called Silicalite-1 molecular sieves) after ball milling seed);

[0037] Step 2: Select a porous ceramic tube with a pore size of 100nm as the carrier, seal both ends of the carrier with glaze, wash and dry, seal the outer surface with PTFE tape, and brush the nano-scale all-silicon MFI molecular sieve seed crystal into the ceramic tube. surface;

...

Embodiment 2

[0048] The difference from Example 1 is that in step 4, the hydrothermal synthesis time is 6 hours, and the rest of the steps are the same as in Example 1.

[0049] The surface and profile of the gained MFI molecular sieve membrane are as follows figure 2 As shown, (a) is the SEM image of the membrane surface; (b) is the SEM image of the membrane section. It can be seen from the figure that the surface of the carrier is completely covered by MFI crystals, and the cross-linking between the crystals is very good (see Figure a); the membrane The thickness is relatively uniform, about 1.04 microns (see Figure b).

[0050] CO of membrane tubes containing MFI molecular sieves on the surface 2 / CH 4 Gas separation test results, at 0.14MPa, its CO 2 The average value of the permeability is 45×10 -7 mol / (m 2 s Pa), CO 2 / CH 4 The average value of separation selectivity is 132. It can be seen that compared with the molecular sieve membranes synthesized by traditional high-tempe...

Embodiment 3

[0053] The difference from Example 1 is that in step 4, the hydrothermal synthesis time is 12 hours, and the rest of the steps are the same as in Example 1.

[0054] The surface and profile of the gained MFI molecular sieve membrane are as follows image 3 As shown in the figure, it can be seen from the figure that the surface of the carrier is completely covered by cubic crystals, and the cross-linking between the crystals is very good (see figure a); the thickness of the film is relatively uniform, about 1.12 microns (see figure b).

[0055] CO of membrane tubes containing MFI molecular sieves on the surface 2 / CH 4 Gas separation test results, at 0.14MPa, its CO 2 The average value of the permeability is 24 x 10 -7 mol / (m 2 s Pa), CO 2 / CH 4 The average separation selectivity is 9. It can be seen that, compared with the traditional high-temperature synthesis, the film thickness of the traditional high-temperature synthesis is about 2-10 microns, which is reduced to 1...

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Abstract

The invention relates to an ultrathin molecular sieve membrane and a preparation method thereof. The method comprises the following steps: (1) preparing a nanoscale seed crystal; (2) uniformly coating a porous carrier tube with the nanoscale seed crystal; (3) preparing molecular sieve membrane synthesis mother liquor; (4) crystallizing the porous carrier tube obtained in the step (2) and the mother liquor obtained in the step (3); (5) after the crystallization is finished, washing and drying the obtained membrane tube; and (6) roasting and cooling to obtain the activated ultrathin molecular sieve membrane. Compared with the prior art, the ultrathin molecular sieve membrane has the advantages that the synthetic mother liquor with high silica-alumina ratio is adopted, an organic template agent is not used, and the film thickness can be effectively adjusted.

Description

technical field [0001] The invention relates to the synthesis field of molecular sieve membranes, in particular to an ultrathin molecular sieve membrane and a preparation method thereof. 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, ZSM-5 and Silicalite-1 molecular sieve membranes with MFI structure have a pore diameter of about 0.55 nanometers, which are suitable for the separation of n-paraffin-isoparaffin, alcohol-water separation, and xylene isomer separation. [0003] At present, the methods for preparing inorganic molecular sieve...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B39/04C01B39/02
CPCC01B39/04C01B39/02C01P2004/03
Inventor 张延风徐宁张野邱恒娥
Owner SHANGHAI UNIV OF ENG SCI
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