Preparation method of fluorine-containing MFI zeolite membrane

A zeolite molecular sieve membrane and zeolite molecular sieve technology, applied in the direction of crystalline aluminosilicate zeolite, etc., can solve the problems of inability to form a dense molecular sieve layer, long synthesis time, high preparation cost, etc., to reduce the content of silicon source and template agent, Save preparation steps and time, mild reaction conditions

Active Publication Date: 2010-09-22
JIANGXI NORMAL UNIV
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Problems solved by technology

[0004] Tavolaro et al. (Desalination, 147 (2002) 333) used sodium fluoride to replace the alkali in the synthesis solution, and successfully prepared VS-1 molecular sieve membrane on the tubular alumina support, but the content of silicon source and template agent in the synthesis sol was relatively low. High (the molar component ratio of the synthetic solution is 0.5VOSO 4 -10NaF-1.25TPABr-10SiO 2 -330H 2 O), and it needs to be crystallized at 170°C for 6 days, and the preparation steps are complicated and cumbersome
Gualtieri et al. (Microp.Mesop.Mater., 111 (2008) 604) utilize hydrofluoric acid to neutralize tetrapropylammonium hydroxide (synthetic liquid molar composition 3TPAOH: 25SiO 2 : 975H 2 (0: 100EtOH: 3HF), the TPA-MFI zeolite molecular sieve membrane was successfully prepared on porous glass and alumina sheet support under neutral conditions, but it needs to be prepared in a thicker (H 2 O/SiO 2 =39) in the synthetic sol at 100°C for 120 hours to ...

Method used

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  • Preparation method of fluorine-containing MFI zeolite membrane
  • Preparation method of fluorine-containing MFI zeolite membrane
  • Preparation method of fluorine-containing MFI zeolite membrane

Examples

Experimental program
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Embodiment 1

[0043] Example 1: Preparation of fluorine-containing MFI zeolite molecular sieve seed crystals

[0044] Mix the template agent tetrapropylammonium hydroxide, sodium hydroxide, silica sol, sodium fluoride and appropriate amount of water evenly, and mix and stir at room temperature to form a stable sol, stir and age for 24 hours, the formed SiO 2 -Na 2 O-TPAOH-MF-H 2 The molar ratio of each component in the O sol system is: MF / SiO 2 =0.15, NaOH / SiO 2 = 0.25, TPAOH / SiO 2 =0.3,H 2 O / SiO 2 =20; the above-mentioned aged sol was put into a polytetrafluoroethylene-lined stainless steel reactor, and then the reactor was placed in an oven preheated to 120°C for crystallization for 30 hours. After the reaction was completed, the reaction solution had obvious stratification. The reaction product was centrifuged, washed to neutral, dried, and put into a muffle furnace at 550°C for 6 hours to remove the template agent to obtain the fluorine-containing all-silicon MFI zeolite molecula...

Embodiment 2

[0046] Example 2: Preparation of fluorine-containing MFI zeolite molecular sieve membrane

[0047] The porous carrier is tubular mullite produced by Japan Nikkato Co., Ltd. (the composition is 67wt.%Al 2 o 3 , 33wt.% SiO 2 ) carrier, the inner and outer diameters are 9 mm and 12 mm respectively, the length is 100 mm, the average pore diameter is about 1 μm, and the porosity is about 43%. After the carrier was smoothed by 1000-mesh sandpaper, it was cleaned by ultrasonic waves in deionized water, and then dried for future use. Then the support is soaked in the methanol solution containing 20wt% dimethyldiethoxysilane, soaked for 20 minutes, the surface of the support is positively charged, and the 5% fluorine-containing MFI zeolite molecular sieve seed crystal (as in Example 1) NaOH solution was added dropwise into the solution to adjust the pH value to 9-10, so that the surface of the seed crystal was negatively charged, and the positively charged support was placed in the ...

Embodiment 3

[0054] Example 3: Preparation of fluorine-containing MFI zeolite molecular sieve membrane

[0055] The synthetic liquid raw material and operating steps that adopt are the same as embodiment 2, and the difference is that the molar proportion of synthetic raw material liquid is F- / SiO 2 =0.5, TPABr / SiO 2 = 0.1, TPAOH / SiO 2 =0.2,H 2 O / SiO 2 =1000, crystallized in an oven at 170°C for 36 hours. The synthesized molecular sieve membrane was confirmed to be MFI zeolite molecular sieve membrane by XRD. Synthetic crystals using 19 Characterization of F and SiF by solid-state NMR technology x 4-x The form exists, that is, F completely enters the crystal skeleton, and the results of plasma emission spectroscopy and F electrode characterization show that the F / Si molar ratio in the crystal is 0.0085.

[0056] The prepared molecular sieve membranes S-3 and S-4 were used for pervaporation characterization in the ethanol / water (5 / 95wt%) system at 60°C, and the results are shown in T...

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Abstract

The invention provides a preparation method of a fluorine-containing MFI zeolite membrane, which is characterized by comprising an ultra-thin synthetic liquid containing fluoride (MF), wherein the molar ratio is 1SiO2: 0.05-1.5MF: 0.05-0.5TPABr: 0.05-0.5TPAOH: 200-2000H2O, and a layer of continuous dense fluorine-containing MFI zeolite membrane is formed on the surface of a porous tubular supporting body coated with fluorine-containing MFI zeolite crystal seeds by using a secondary growth hydrothermal method. The pervaporation test is carried out for the prepared MFI zeolite membrane in an ethanol / water (5/95wt%) system at the temperature of 60 DEG , and the permeation flux and the separation factor can be respectively up to 2.85kg/m2. h and 68. The method has mild conditions of preparation process, and simple and fast operation step, and greatly reduces the contents of a silicon source and a template agent in the synthetic liquid, thereby greatly reducing the preparation cost of the membrane, and obviously improving the permeability of the MFI zeolite membrane; and the fluorine-containing MFI zeolite membrane has wide application prospects in the fields of the separation of liquid such as organic matter / water mixture, gas separation, membrane reactors and the like.

Description

technical field [0001] The invention provides a preparation technology for synthesizing a fluorine-containing MFI zeolite molecular sieve membrane material and its recovery application in a low-concentration organic matter / water mixture, belonging to the field of molecular sieve membrane material preparation and application. Background technique [0002] Zeolite molecular sieve membrane is a new type of microporous inorganic membrane material developed in recent years. Because of its good chemical and mechanical stability, it can meet the requirements of high flux, high selectivity, heat resistance and solvent resistance. People pay attention to it, and it has quickly become the most promising research hotspot in the field of membrane separation. In particular, the MFI zeolite molecular sieve membrane has an excellent pore structure. It has two cross-linked pore systems, one is a linear channel in the b-axis direction with a pore size of 0.53×0.56nm, and the other is a sinus...

Claims

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Application Information

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IPC IPC(8): C01B39/04
Inventor 陈祥树周荣飞张小亮朱美华孔佑鑫
Owner JIANGXI NORMAL UNIV
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