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Rapid crystallization method for synthesizing EMT molecular sieve

A molecular sieve, chemical synthesis technology, applied in chemical instruments and methods, molecular sieves and alkali exchange compounds, inorganic chemistry, etc., can solve the problems of slow crystallization rate, shortened crystallization time, shortened crystallization time, etc. Effects of generation, increased mass transfer rate, and shortened crystallization time

Active Publication Date: 2018-03-20
SHANGHAI LVQIANG NEW MATERIALS CO LTD +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

18-crown-6 is expensive, and it is used in a large amount in the process of synthesizing EMT molecular sieves. If 18-crown-6 ether is not used, the synthesized molecular sieve contains a large amount of miscellaneous crystals, and the crystallization rate is slow
[0004] Scientific research workers have done a lot of research on how to reduce the amount of templates used, as reported in the literature Microporous And Mesoporous Materials, 1999,28 (3): 361-375 by the method of constantly rotating the reactor during the entire synthesis process (STNTFF method ), successfully in ether / Al 2 o 3 =0.143, the pure EMT zeolite was synthesized, but the crystallization time of the sample was as long as 25 days, and the crystallinity of the sample was not high
CN1369433A discloses a synthetic method of EMT zeolite, using 18-crown-6 ether as a template, and adding a certain amount of phosphorus-containing inorganic salt emulsions such as sodium phosphate, sodium dipolyphosphate, sodium pentapolyphosphate, etc. to the synthesis system, The amount of crown ether can be reduced by 40% to 50% (mole), and the crystallization time can be shortened, but the use of phosphorus-containing additives may cause a small amount of phosphorus in the zeolite, which affects the catalytic activity of EMT molecular sieves
These synthetic methods cannot obtain EMT zeolites in the hexagonal crystal phase
CN1951809A discloses a method for synthesizing EMT molecular sieves using polyethylene glycol as a template. Crystallization takes 2 to 7 days in a conventional hydrothermal environment, which shortens the crystallization time to a certain extent, but the synthesized samples contain a large amount of impurities. crystal
The seed crystal that this invention uses needs to use excessive crown ether to prepare (18-crown-6 ether / Al 2 o 3 =1.0), and the synthesis time of the seed crystal takes 15 days, and the energy consumption is relatively large
The research on the synthesis of EMT molecular sieves without templates has also achieved a major breakthrough. In the literature Science, 2012, 335:70-73, ultra-small EMT zeolite, with nanostructured crystal nuclei, the synthesis time is shortened to 36h, the synthesis temperature is 30°C lower, but the relative crystallinity is low

Method used

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  • Rapid crystallization method for synthesizing EMT molecular sieve
  • Rapid crystallization method for synthesizing EMT molecular sieve
  • Rapid crystallization method for synthesizing EMT molecular sieve

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0042] At room temperature, weigh 4.976g of sodium metaaluminate, add 20.000g of water, add 7.923g of sodium hydroxide during stirring, stir and mix until a clear solution, and place it at room temperature. Weigh 24.0g of silica sol with a mass fraction of 25%, add 20g of sodium hydroxide, add 40g of water during the process, stir and dissolve continuously, and when the solution is cooled to room temperature, slowly add the configured sodium metaaluminate solution dropwise, and stir for 2h. Crystallize at 30°C for 36h to obtain the desired EMT molecular sieve seed A, figure 1 The XRD spectrum of the prepared EMT seed crystal, the characteristic peaks of the spectrum are consistent with those reported in the literature [Science, 2012, 335:70-73].

Embodiment 2

[0044] At room temperature, weigh 10.00g of sodium metaaluminate and 1.80g of sodium hydroxide, add 100.2g of water, stir continuously, add 40.00g of sodium hydroxide, continue stirring until clear, cool to room temperature for later use. Weigh 57.70g of water glass with a modulus of 3.2, add 80.3g of water, and add 20.0g of sodium hydroxide during the stirring process. After stirring evenly and cooling to room temperature, slowly add sodium metaaluminate solution dropwise, and stir for 0.5h to obtain the obtained The desired EMT molecular sieve seed crystal B.

Embodiment 3

[0046] In the hydrothermal synthesis environment, the effects of different hydrothermal crystallization temperatures on the synthesis of EMT molecular sieves were investigated.

[0047] At room temperature, weigh 4.976g of sodium metaaluminate, add 10.8g of water, add 1.50g of sodium hydroxide during stirring, mix and stir until a clear solution, and cool for later use. Weigh 72.0g of silica sol with a mass fraction of 25%, add 0.529g template agent (18-crown-6 ether), mix and stir until the template agent is completely dissolved, then slowly add sodium metaaluminate solution dropwise, stir for 6h, then add 2. 232g of seed crystal A, transferred to a polytetrafluoroethylene-lined stainless steel reactor, crystallized at 70°C, 80°C, 90°C, 100°C, and 110°C for 48 hours, filtered, washed, and dried to obtain a molecular sieve sample . The obtained results are listed in Table 1.

[0048] Synthetic EMT molecular sieve result under table 1 embodiment 3 different temperatures

[0...

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Abstract

The invention relates to a rapid crystallization method for synthesizing EMT molecular sieve. In a synthetic system, an EMT molecular sieve seed crystal synthesized under the condition of no templateagent is added and made into a gel. After the gel is aged, the gel is hydrothermally crystallized for 12 to 72 hours, and then crystallized under microwave conditions for 4 to 360 minutes to synthesize the EMT molecular sieve. Compared with the prior art, the method for synthesizing the EMT molecular sieve has a small use amount of the template agent, short molecular crystallization time, high degree of crystallinity, and low energy consumption.

Description

technical field [0001] The invention relates to the field of molecular sieve preparation, in particular to a method for rapidly crystallizing and synthesizing EMT molecular sieves. Background technique [0002] EMT molecular sieves belong to the hexagonal crystal system, and the space group is P6 3 / mmc, unit cell parameters a=b=1.7374nm, c=2.8365nm, skeleton density is 12.9T / nm 3 . EMT molecular sieve has a three-dimensional twelve-membered ring channel system and has strong acidity. In petroleum processing, EMT zeolite is used in the hydrocracking of long-chain alkanes, butene-isobutane alkylation and fluid catalytic cracking (FCC) reactions. It has excellent catalytic performance and broad application prospects. There have been many reports on the application of this large-pore zeolite with good industrial application prospects in catalysis and adsorption, especially in the catalytic reaction of isobutane / 2-butene alkylation to produce high-octane gasoline, EMT Zeolit...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B39/48
CPCC01B39/48C01P2002/72C01P2004/03
Inventor 夏思奇徐华胜李春成胡杰王鹏飞余金鹏
Owner SHANGHAI LVQIANG NEW MATERIALS CO LTD
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