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Method for synthesizing highly-oriented MFI (Melt Flow Index) molecular sieve membrane through controlled secondary growth of twin crystal

A secondary growth and orientation technology, applied in molecular sieves and alkali exchange compounds, chemical instruments and methods, inorganic chemistry, etc., can solve the problems of cumbersome steps, complicated operation steps, high preparation costs, etc., and achieve good orientation and film layer Continuous, easy-to-use effects

Inactive Publication Date: 2012-12-26
ZHEJIANG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The advantages of the in-situ hydrothermal synthesis method are simple operation, strong applicability, and low cost; however, while the in-situ hydrothermal synthesis method forms a molecular sieve membrane on the support, a large number of molecular sieve crystals are also formed in the bulk phase, and it is difficult to avoid twinning. generation, making it difficult to synthesize highly oriented molecular sieve membranes
[0004] The secondary growth method for synthesizing oriented molecular sieve membranes can better control the oriented growth of molecular sieve crystals because of the use of oriented seed crystal layers; however, the secondary growth method needs to obtain a uniformly coated seed crystal layer, and the operation steps are relatively complicated The preparation cost is high, and the secondary growth process is often accompanied by the formation of other orientation twins, which affects the orientation of the molecular sieve membrane
In the secondary growth process, the preheated synthetic solution is the key, if using fresh synthetic solution will generate a large number of a Axis-oriented twins, cannot obtain height b Axial Oriented MFI Molecular Sieve Membrane
[0008] The above-mentioned secondary growth method either uses a special complex structure-directing agent, or the steps are cumbersome, or the energy consumption is high, the pollution is serious, and the cost is high

Method used

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  • Method for synthesizing highly-oriented MFI (Melt Flow Index) molecular sieve membrane through controlled secondary growth of twin crystal
  • Method for synthesizing highly-oriented MFI (Melt Flow Index) molecular sieve membrane through controlled secondary growth of twin crystal
  • Method for synthesizing highly-oriented MFI (Melt Flow Index) molecular sieve membrane through controlled secondary growth of twin crystal

Examples

Experimental program
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Effect test

Embodiment 1

[0029] Apply the MFI type molecular sieve seed crystal powder to the surface of the smooth support, and then press and smooth it with a little force, that is, it is coated with b A support for the axis-oriented seed layer. Scanning electron microscope pictures of the seed layer as figure 1 shown.

Embodiment 2

[0031] 40 milliliters of synthetic solution that the molar ratio is ethyl tetrasilicate: sodium hydroxide: water=1:0.20:165 was stirred at room temperature for 4 hours to obtain a clear and transparent solution, and then this synthetic solution was mixed with the coating prepared in Example 1 The support with the seed layer was placed together in a 100 ml synthesis kettle with a polytetrafluoroethylene liner, and then the sealed synthesis kettle was placed in a blast oven at 200°C for 10 minutes of crystallization, and finally the crystal The thawed synthesis kettle was taken out, and after quenching to room temperature, the support body was taken out, washed with deionized water, and then dried. The scanning electron microscope pictures of the dried molecular sieve membranes are as follows: figure 2 As shown, the obtained molecular sieve membrane is highly b Axially oriented MFI type molecular sieve membrane, but discontinuous.

Embodiment 3

[0033] 40 milliliters of synthetic solution that molar ratio is tetrapropyl ammonium hydroxide: sodium hydroxide: water=1:0.001:0.10:165 is stirred at room temperature for 10 hours, obtains clear and transparent solution, then this The synthetic solution and the support coated with the seed layer prepared in Example 1 were put into a 100 ml synthesis kettle with a polytetrafluoroethylene liner, and then the sealed synthesis kettle was put into a blast oven at 150° C. The internal crystallization was carried out for 3 hours, and finally the synthesis kettle after crystallization was taken out, and the support body was taken out after quenching to room temperature, washed with deionized water, and then dried. The scanning electron microscope pictures of the dried molecular sieve membranes are as follows: image 3 As shown, the obtained molecular sieve membrane is highly b Axially oriented MFI type molecular sieve membrane.

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Abstract

The invention discloses a method for synthesizing a highly-oriented MFI (Melt Flow Index) molecular sieve membrane through controlled secondary growth of a twin crystal. The method comprises the following steps of: (1) preparing secondary growth synthetic fluid consisting of ethyl orthosilicate, tetrapropyl ammonium hydroxide, sodium hydroxide and water in the molar ratio of 1:(0.001-0.60):(0.001-0.20):(10-1000); (2) stirring the synthetic fluid at room temperature for 1-10 hours, putting the stirred synthetic fluid into a synthesis kettle, putting a support body coated with a b axis oriented crystal seed layer into the synthesis kettle, sealing the synthesis kettle, heating, and synthesizing at the temperature of between 120 DEG C and 200 DEG C for 10-300 minutes; and (3) washing and drying to obtain the oriented MFI molecular sieve membrane from the support body. The MFI molecular sieve membrane synthesized by the method is highly oriented in a b axis, the method is easy to operate, a molecular sieve membrane layer has high orientation, the synthetic fluid can be recycled, cost is lowered, and pollution is reduced.

Description

technical field [0001] The invention relates to the synthesis of MFI molecular sieve membranes, and in particular provides a method for synthesizing highly oriented MFI molecular sieve membranes through controlled secondary growth of twins. Background technique [0002] Molecular sieve membrane has a regular pore structure, unique mechanical and electronic properties, and excellent thermal stability, chemical stability and biological stability, so it is widely used in material separation, membrane reactors, chemical sensors, electrodes, low dielectric Constant materials and anti-corrosion coatings and many other fields. At present, the molecular sieve membranes reported in the literature mainly include LTA type, T type, MFI type, FAU type, MOR type, etc., among which the MFI type molecular sieve membrane has attracted much attention. This is because: (1) the pore size of the MFI molecular sieve is equivalent to the molecular size of many important industrial chemicals; (2) ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C01B39/00
Inventor 王正宝李显明彭勇
Owner ZHEJIANG UNIV
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