Biquaternary ammonium salt and method for synthesizing MFI type molecular sieve and molecular sieve membrane

A double quaternary ammonium salt and molecular sieve technology, which is applied in the direction of molecular sieves and base exchange compounds, chemical instruments and methods, and the preparation of organic compounds, can solve the problems of expensive raw materials, slow growth, and complex synthesis of templates Growth rate, effect of increased size

Inactive Publication Date: 2017-06-13
NINGXIA UNIVERSITY
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  • Abstract
  • Description
  • Claims
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Problems solved by technology

[0008] In order to solve the problem of the synthesis process of MFI type molecular sieve, the growth rate of molecular sieve crystals along the a-axis and c-axis direction is relatively fast, and the growth rate along the b-axis direction is very slow; the synthesis process of the template agent in the traditional route is complex and the preparation of raw materials is relatively expensive. Problem; The present invention provides a kind of cheap double quaternary ammonium salt templating agent, i.e. TPA + Dimer (dimer-TPA); Simultaneously, provide the synthetic method of this double quaternary ammonium salt template agent that synthetic process is simple; In addition, provide a kind of method that adopts double quaternary ammonium salt template agent to synthesize MFI type molecular sieve, and further A method for synthesizing MFI molecular sieve membranes using a double quaternary ammonium salt template is provided

Method used

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  • Biquaternary ammonium salt and method for synthesizing MFI type molecular sieve and molecular sieve membrane
  • Biquaternary ammonium salt and method for synthesizing MFI type molecular sieve and molecular sieve membrane
  • Biquaternary ammonium salt and method for synthesizing MFI type molecular sieve and molecular sieve membrane

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0041] The preparation of hexapropylhexamethylene diammonium bromide (dimer-TPABr) template, the preparation method is as follows: get 1,6-dibromohexane as 18g, tri-n-propylamine 35mL, be dissolved in 30mL dehydrated alcohol or acetonitrile , and placed in a round-bottomed flask for reflux and stirring, the reflux temperature is 75-85°C; the reaction time is 40-50h. After cooling, it was dissolved in ethyl acetate for recrystallization, and the white solid powder obtained by recrystallization was placed in an oven at 60°C and dried to obtain hexapropylhexamethylene diammonium bromide (dimer-TPABr) template agent. Store in a desiccator.

[0042] The reaction equation is:

[0043]

[0044] The chemical structure of the product is characterized by a BRUKER AV400 nuclear magnetic resonance instrument, TMS is used as an internal standard, and the unit is ppm; its 13CNMR spectrum is as follows: figure 1 As shown, the chemical shift δ corresponding to each carbon atom in the fig...

Embodiment 2

[0046] The preparation of hexapropylhexamethylene diiodide ammonium iodide (dimer-TPAI) template is as follows: get 20g of 1,6-diiodohexane, 40mL of tri-n-propylamine, dissolve in 30mL of ethyl acetate, place in a circular Reflux and stir in the bottom flask, the reaction reflux temperature is 85-100°C, the reaction time is 30-40h, after cooling, it is dissolved in ethyl acetate for recrystallization, and the white solid powder obtained by recrystallization is dried in an oven at 60°C , to obtain hexapropylhexamethylene diiodide ammonium (dimer-TPAI) template agent, stored in a desiccator. The reaction equation is as follows:

[0047]

[0048] The chemical structure of the product is characterized by BRUKER AV400 nuclear magnetic resonance instrument, TMS is used as the internal standard, and the unit is ppm; the chemical shift δ corresponding to each carbon atom in the 13CNMR spectrum is: 11.0(3), 16.0(3), 22.2(1), 26.4(1 ), 59.3(1), 61.1(3), which are basically consistent ...

Embodiment 3

[0050] Synthesis of MFI-type molecular sieves using diquaternary ammonium salts as templates:

[0051] (1) According to ethyl orthosilicate: KOH: dimer-TPABr: H 2 O=40:25:7.5:9500 molar ratio, mix KOH, dimer-TPABr and deionized water to form a solution, and then add tetraethyl orthosilicate dropwise to the solution under vigorous stirring, at 25°C Aged for 5 hours to obtain MFI type molecular sieve synthetic gel.

[0052] (2) Transfer the obtained synthetic gel of molecular sieve into a closed stainless steel reaction kettle with polytetrafluoroethylene lining, hydrothermally crystallize at 175°C for 24 hours, take out the sample and cool it, wash with distilled water, dry, and recover the molecular sieve sample . Molecular sieve crystals were characterized by a Japanese Rigaku D / MAX-2200PC X-ray powder diffractometer and a KYKY-2800 scanning electron microscope. The X-ray diffraction spectrum and scanning electron microscope (SEM) photos are shown in figure 2 and image ...

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Abstract

The invention provides a biquaternary ammonium salt template agent which has the chemical structural formula shown in the description, wherein R represents an n-propyl, and X represents any one of Cl, Br and I. A synthesis method of the biquaternary ammonium salt template agent comprises the following steps: dissolving 1, 6-haloalkane and tri-n-propylamine into an organic solvent, fully mixing, placing the mixture into a container for heating reflux at the temperature of 70-150 DEG C, performing a nucleophilic substitution reaction for 12-72h, cooling, recrystallizing and drying, so as to obtain biquaternary ammonium salt, wherein the organic solvent comprises one or more of anhydrous ethanol, ethyl acetate, acetonitrile and butanone. The invention also comprises a method for synthesizing the MFI type molecular sieve by adopting the biquaternary ammonium salt template agent and a method for synthesizing the MFI type molecular sieve membrane by adopting the biquaternary ammonium salt template agent. The biquaternary ammonium salt template agent is prepared by utilizing cheap raw materials and adopting simple synthesis processes; when the MFI type molecular sieve is prepared, the growing rate of a crystal of the MFI type molecular sieve in a b-axis direction can be increased, therefore, the dimension of the crystal in the b-axis direction is enlarged, and the growing rate of the crystal in an a-axis direction is inhibited.

Description

[0001] Technical field: [0002] The invention belongs to the technical field of molecular sieve synthesis, and in particular relates to a diquaternary ammonium salt and a method for synthesizing MFI molecular sieves and molecular sieve membranes. [0003] Background technique: [0004] As a new type of inorganic membrane material, zeolite molecular sieve membrane has developed rapidly in recent decades and is widely used in various disciplines such as medical research, environmental protection, metallurgical process, chemical process and food science. Among them, the MFI molecular sieve membrane has a more prominent application prospect due to its uniform pore size distribution and good thermal stability. For MFI molecular sieve membranes, the b-axis oriented molecular sieve membrane has the shortest mass transfer path and is more conducive to molecular diffusion. The mass transfer performance is better than other oriented or non-oriented zeolite membranes, and has significant...

Claims

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Application Information

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IPC IPC(8): C01B39/48C07C209/12C07C211/63B01D71/02
CPCB01D71/028C01B39/48C01P2002/72C01P2004/03C07C209/12C07C211/63
Inventor 王政苏美慧魏慧丽安梅
Owner NINGXIA UNIVERSITY
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