Controllable synthesis method of pure silicon and high-silicon CHA molecular sieves

A synthesis method and molecular sieve technology, applied in the fields of crystalline aluminosilicate zeolite, bulk chemical production, ethylene production, etc., can solve problems such as poor uniformity, difficulty in controlling particle size and distribution, complicated mother liquor preparation process, etc., and achieve reduction of raw materials Cost, wide particle size distribution, and the effect of simplifying the synthesis process

Active Publication Date: 2020-08-18
SHANGHAI UNIV OF ENG SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] This has led to a series of problems, such as the complicated and poor uniformity of the mother liquor preparation process, resulting in poor reproducibility of molecular sieve preparation, difficulty in particle size and distribution control, etc.

Method used

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  • Controllable synthesis method of pure silicon and high-silicon CHA molecular sieves
  • Controllable synthesis method of pure silicon and high-silicon CHA molecular sieves
  • Controllable synthesis method of pure silicon and high-silicon CHA molecular sieves

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preparation example Construction

[0058] Various embodiments relate to a method for the controllable synthesis of pure silicon and high silicon CHA molecular sieves. Using traditional N,N,N-trimethyl-1-adamantyl ammonium hydroxide (TMAdaOH) as the template, using ammonium hexafluorosilicate, or a mixture of common silicon sources and fluorides as the silicon source, in H 2 O / SiO 2 Pure silicon and high-silicon CHA molecular sieves are efficiently and rapidly synthesized in a dilute solution of about 30 to achieve effective regulation of crystal size and reduce the amount of templates used. Specifically include the following steps:

[0059] (1) Perform ball milling on the pure silicon CHA molecular sieve crystal seed crystals. After ball milling, the molecular sieve crystals obtained from the CHA nanocrystal seeds are deeply fragmented and amorphized, and what are obtained are fine CHA molecular sieve crystals and amorphous particles. All smaller than 100 nanometers, or even smaller;

[0060] (2) After mixin...

Embodiment 1

[0068] Embodiment 1, this embodiment aims at synthesizing a kind of all silicon CHA molecular sieve

[0069] A controllable synthesis method of pure silicon CHA molecular sieve, the specific steps are as follows:

[0070] Step 1: Mix ethyl orthosilicate and N,N,N-trimethyl-1-adamantyl ammonium hydroxide, stir for 4 hours, then place in an oven at 80 degrees Celsius to remove excess water and ethanol, then Add hydrofluoric acid, stir to obtain the seed crystal synthesis mother liquor, the SiO in the mother liquor 2 , HF, trimethyladamantyl ammonium hydroxide (TMAdaOH) and H 2 The molar ratio of O is 1.0:0.5:0.5:3. Crystallize at 453K for 48 hours to obtain pure silicon CHA molecular sieve seeds. The molecular sieve seed crystals are relatively large, about 8 microns. After being ball-milled by a ball mill, the crystals are pulverized to below 500 nanometers;

[0071] Step 2: Mix ethylenediamine (EDA), organic template N,N,N-trimethyl-1-adamantyl ammonium hydroxide (TMAdaOH...

Embodiment 2

[0076] The difference from Example 1 is that in step 4, crystallization was carried out at 433K for 6 hours.

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Abstract

The invention relates to a controllable synthesis method of pure silicon and high-silicon CHA molecular sieves. N,N,N-trimethyl-1-adamantyl ammonium hydroxide (TMAdaOH) is used as a template agent; ammonium hexafluorosilicate is used as a silicon source; or a mixture of a common silicon source and fluoride is used as a silicon source; pure silicon and high-silicon CHA molecular sieves are efficiently and rapidly synthesized in a dilute solution with the H2O/SiO2 ratio of about 30, effective regulation and control of the crystal size are achieved, meanwhile, the use amount of the template agentis reduced, the cost is reduced, and the pure silicon and high-silicon CHA molecular sieves can be efficiently and rapidly synthesized at a low temperature. Compared with the prior art, the CHA molecular sieve synthesis steps are simple, the mother liquor uniformity is good, the molecular sieve preparation repeatability is good, the particle size and distribution control is simple, and the industrial application of the CHA molecular sieves is facilitated.

Description

technical field [0001] The invention relates to the field of molecular sieve synthesis, in particular to a controllable synthesis method of pure silicon and high silicon CHA molecular sieves. Background technique [0002] Molecular sieves are a class of aluminosilicate crystal materials with molecular-scale pores. Molecular sieves have high specific surface area and porosity, uniform micropores, adjustable acidity, unique adsorption properties, excellent stability, etc., and are widely used in catalysis, adsorption, and ion exchange processes. Small-pore molecular sieves with eight-membered rings mainly include CHA, SSZ-13, SAPO-34, DDR and LTA molecular sieves, which are widely used in the fields of catalysis, adsorption and separation. Among them, the silicon-aluminum CHA molecular sieve has a three-dimensional pore structure and a lower skeleton density, and is superior to other molecular sieves in terms of adsorption and membrane separation. Although CHA zeolites have ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B39/04
CPCC01B39/04C04B2235/96C01P2002/72C01P2004/03C01P2004/61Y02P30/40
Inventor 张延风邱恒娥孔雪
Owner SHANGHAI UNIV OF ENG SCI
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