Method for preparing high-performance Silicalite-1 molecular sieve membrane by using TPABr as template agent

A technology of tetrapropylammonium bromide and templating agent, applied in chemical instruments and methods, molecular sieves and base exchange compounds, inorganic chemistry, etc., can solve the problem of low flux of molecular sieve membranes, high price of TPAOH, hindering Silicalite-1 molecular sieve membranes Industrial application and other issues, to achieve cost reduction, good thermal stability and repeatability, and reduce preparation costs

Active Publication Date: 2010-02-17
JIANGXI NORMAL UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
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AI Technical Summary

Problems solved by technology

[0006] Because TPAOH is expensive, it will hinder the industrial application of Silicalite-1 molecular sieve membrane
In 2006, the patent CN1795971A disclosed that tetrapropylammonium bromide (TPABr) was used as a template, and multiple in-situ hydrothermal methods were used in (H 2 O / SiO 2 =80) successfully prepared Silicalite-1 molecular sieve membrane, but the molecular sieve membrane flux is low, 60 ℃ to the flux of the mixed solution of 3wt% ethanol and water is about 0.37kg / m 2 .h
[0007] In the existing reports, most of the Silicalite-1 molecular sieve membranes investigated by the researchers used TPAOH as the template agent, and in the thicker synthetic solution (H 2 O / SiO 2 2 O / SiO 2 >300), especially at H 2 O / SiO 2 The synthesis of the molar ratio in the range of 500-750 has not been reported in the literature

Method used

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  • Method for preparing high-performance Silicalite-1 molecular sieve membrane by using TPABr as template agent
  • Method for preparing high-performance Silicalite-1 molecular sieve membrane by using TPABr as template agent
  • Method for preparing high-performance Silicalite-1 molecular sieve membrane by using TPABr as template agent

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Experimental program
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Embodiment 1

[0044] Synthesis of embodiment 1 Silicalite-1 molecular sieve crystal

[0045] Take a certain amount of TPABr aqueous solution and flaky NaOH dissolved in deionized water, stir to dissolve and cool to room temperature, then continue to add a certain amount of silica sol to the above solution, and finally the composition (molar ratio) of each component in the solution is SiO 2 : 0.3TPABr : 0.25NaOH : 45H 2 O, then aging at room temperature, after aging for 24 hours, put it into a stainless steel reactor, and put the stainless steel reactor into an oven at 100°C for 24 hours. The synthesized crystals were washed with deionized water until neutral and then dried. After drying, they were placed in a muffle furnace and calcined at 550° C. for 12 hours to remove the template agent (such as figure 1 ). Calcined crystals are detected by XRD (X-ray diffraction) and show to be Silicalite-1 molecular sieve crystals (such as figure 2 ), and the molecular sieve crystal is the shape of ...

Embodiment 2

[0046] Embodiment 2 Preparation of Silicalite-1 molecular sieve membrane

[0047] The carrier used in this experiment is the tubular mullite produced by Japan Nikkato Co., Ltd. (the composition of mullite is 67wt.%Al 2 o 3 and 33wt.% SiO 2 ) as a carrier for synthesizing Silicalite-1 membrane, the inner diameter and outer diameter of the carrier are 9mm and 12mm respectively, the length is 100mm, the porosity is about 43%, and the average pore diameter is about 1 μm. Ultrasonic cleaning in deionized water and drying for later use. The dried carrier is coated with self-made Silicalite-1 molecular sieve.

[0048] Weigh a certain amount of TPABr, NaOH and deionized water and stir evenly to make it a uniform solution, then add a certain amount of TEOS to the above solution and continue stirring and aging at room temperature until it becomes a clear and transparent solution , the composition (molar ratio) of each component in this solution is TEOS: 0.3TPABr: 0.2NaOH: 500H 2 O....

Embodiment 3

[0053] Embodiment 3 Preparation of Silicalite-1 molecular sieve membrane

[0054] The raw materials and preparation steps of the synthetic solution used were the same as in Example 2, except that the crystallization time was shortened to 12 hours. After calcination, the Silicalite-1 molecular sieve membrane was used for pervaporation experiments and characterizations. The results of the pervaporation experiments are shown in S-3 and S-4 in Table 2.

[0055] Table 2 Pervaporation separation performance of Silicalite-1 molecular sieve membrane on mullite carrier (60℃)

[0056]

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Abstract

The invention discloses a method for preparing a high-performance Silicalite-1 molecular sieve membrane, which comprises the following steps: using cheap TPABr and silica sol as raw materials for preparing a high-activity Silicalite-1 molecular sieve crystal; using the crystal as a seed crystal to be loaded on the outer surface of a supporting body, and carrying out the high-temperature hydrothermal crystallization in the diluted synthetic liquid using TPABr as the template agent to obtain the high-performance Silicalite-1 molecular sieve membrane. The invention is characterized by adopting asecondary growth hydrothermal method and carrying out the high-temperature (180-210 DEG C) hydrothermal one-step synthesis of the diluted synthetic liquid using TPABr as the template agent (300-750 ofH2O/SiO2, 0.1-0.5 of TPABr/SiO2, and 0.1-0.5 of NaOH/SiO2) on the surface of a porous tubular mullite carrier to form the high-performance Silicalite-1 molecular sieve membrane. The method not only effectively uses the cheap TPABr to replace TPAOH to prepare the molecular sieve membrane, but also greatly reduces the demand quantity of the silicon source and the template agent in the membrane synthetic liquid, thereby greatly reducing the membrane preparing cost. By applying the prepared Silicalite-1 molecular sieve membrane to a pervaporation test in a 60 DEG C ethanol/water (5/95 wt %) mixedsystem, the permeation flux and the separation factor can reach 1.71kg/m<2>.h and 66 respectively. The invention obviously improves the permeation flux and the selectivity of the Silicalite-1 molecular sieve membrane, reduces the production cost and is suitable for industrial production.

Description

technical field [0001] The invention provides a kind of dilute synthetic solution (H 2 O / SiO 2 =300~750), a method for rapidly forming a layer of silicalite-1 molecular sieve crystals on the outer surface of the porous mullite tube. It belongs to the field of permeation separation of inorganic materials. Background technique [0002] MFI molecular sieves have two interlinked 10-membered ring channel systems formed by Si-O-Si, which are linear channels with a size of 0.53×0.56 nm in the b-axis direction and sinusoidal channels with a size of 0.51×0.55 nm in the a-axis direction. tunnel. The pore size of MFI molecular sieve is close to the molecular dynamics diameter of several commonly used substances in the industry. Its well-developed pore system makes it easy for molecules to diffuse and not easy to block. MFI-type molecular sieve crystals are mostly benzene rings, which are beneficial to the formation of membranes, so they have attracted extensive attention from many ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B39/00
Inventor 陈祥树周荣飞朱美华孔佑鑫
Owner JIANGXI NORMAL UNIV
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