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Method for improving stability of MOFs (metal-organic frameworks)

A metal-organic framework and stability technology, applied in organic chemistry, zinc organic compounds, etc., can solve problems such as poor stability, and achieve the effects of improved catalytic performance, improved stability, and good stability

Inactive Publication Date: 2013-04-17
DALIAN INST OF CHEM PHYSICS CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0003] However, MOFs materials also have obvious disadvantages, that is, poor stability, especially hydrothermal stability

Method used

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  • Method for improving stability of MOFs (metal-organic frameworks)
  • Method for improving stability of MOFs (metal-organic frameworks)
  • Method for improving stability of MOFs (metal-organic frameworks)

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 2

[0037] Embodiment 2 ligand exchange method improves the hydrothermal stability of ZIF-8

[0038] Ligand exchange method modification process (the schematic diagram is as follows Figure 5 shown): Disperse the dried ZIF-8 powder, imidazole derivative (5,6-dimethylbenzimidazole, DMBIM), base auxiliary agent (triethylamine, TEA) in methanol, the mass The ratio is: ZIF-8 / DMBIM / TEA / MeOH=1:1:0.7:160. The above solution was sealed and left to stand in a 60°C oven for 15h. Wash with methanol and dry under vacuum at 85°C. The synthesized material was designated as ZIF-8-DMBIM, which was obtained by Figure 6 aInfrared spectrum shows that ZIF-8-DMBIM is at 813cm -1 and 856cm -1 The C-H vibration on the benzene ring appears, and the 3100cm -1 The NH vibration at the point disappears, indicating that DMBIM has been successfully coordinated to ZIF-8. In the wavelength range of 300-600nm, the absorbance of ZIF-8-DMBIM increases gradually with the increase of the incident light wavele...

Embodiment 3

[0040] The adsorption and separation performance of ZIF-8-DMBIM after the ligand exchange of embodiment 3

[0041] After ligand exchange, by Figure 9 It can be seen that the BET surface area of ​​ZIF-8 did not change significantly, only decreased by 1.0% (from 1360 to 1346m 2 / g), the pore distribution did not change significantly. The adsorption amount of isobutanol was only reduced by 5.6% ( Figure 10 , from 0.36 to 0.34g / g). ZIF-8-DMBIM can stably and selectively adsorb isobutanol from water without changing the crystal structure (ZIF-8 crystals will decompose under this condition, see Figure 11 ). ZIF-8 and ZIF-8-DMBIM were incorporated into silicone rubber (PMPS) membranes, and ZIF-8-DMBIM-PMPS membranes could better enrich isobutanol from water than ZIF-8-PMPS membranes ( Figure 12 ), and good stability ( Figure 13 ).

Embodiment 4

[0042] Generality of Example 4 Ligand Exchange Reaction

[0043] Adopt the same proportioning as Example 2, just adopt different imidazole derivatives (2-methyl 4-trifluoromethylimidazole (MTFMIM), 4-trifluoromethylimidazole (TFMIM), 2-ethylimidazole (EIM), 2-isopropylimidazole (IPIM) and benzimidazole (BIM))), the hydrothermal stability of ZIF-8 has been improved to varying degrees ( Figure 14 ).

[0044] Using the same ratio as in Example 2, replacing ZIF-8 with ZIF-7 and ZIF-93, the ligand-modified ZIF-7 and ZIF-93 have good hydrothermal stability, and crystal decomposition is effectively inhibited ( Figure 15 , 16).

[0045] Embodiment 4 metal exchange reaction and versatility

[0046] Metal exchange modification process: the dried ZIF-8 powder, metal salt (ZrCl 4 ) dispersed in methanol, its mass ratio is: ZIF-8 / ZrCl 4 / MeOH=1:2:160. The above solution was sealed and left to stand in a 60°C oven for 15h. Wash with methanol and dry under vacuum at 85°C. The obtai...

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Abstract

The invention provides a method for improving the stability of MOFs. The method includes adopting a ligand exchange method to improve the stability of the MOFs, enabling the mole ratio formula to be ZIFs (zeolitic imidazolate frameworks):a imidazole derivatives:b alkaline adjuvants, wherein a is equal to 0.01-1,000, and b is equal to 0-1,000; adopting a central metal exchange method to improve the stability of the MOFs, enabling the mole ratio formula to be ZIFs:c metal salts, wherein c is equal to 0.01-1,000; when the metal and the ligand are exchanged, using hydrothermal or microwave heating for synthesis with the synthesis temperature to be 20 DEG C to 200 DEG C and the synthesis time to be 1-6,000 min; and washing and drying. The MOFs obtained through modification are provided with high adsorptive separation property and catalysis in a water system, and are good in synthesis repeatability.

Description

Technical field: [0001] The invention relates to the field of modification and application of metal organic frameworks, and in particular provides a method for increasing the stability of metal organic frameworks. Background technique: [0002] Metal-organic frameworks (MOFs) refer to materials with a periodic network structure formed by self-assembly with metal centers as nodes and organic ligands as links. In the field of porous materials, MOFs materials have gradually become the focus of researchers because of their structural diversity and modifiability, and they have great potential in the fields of guest molecule storage, adsorption, separation, catalysis, and sensing. potential application value. [0003] However, MOFs materials also have obvious disadvantages, that is, poor stability, especially hydrothermal stability. Zeolite-like imidazole framework esters (ZIFs) are a kind of MOFs, and literature reports believe that the hydrothermal stability of this type of ma...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07F3/06C07F19/00
Inventor 杨维慎刘新磊李砚硕刘杰
Owner DALIAN INST OF CHEM PHYSICS CHINESE ACAD OF SCI
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