Search

CN-122006529-A - CO under humid condition through hydrophobic regulation and control of pore environment2Preparation method of separated MOF-based mixed matrix membrane

CN122006529ACN 122006529 ACN122006529 ACN 122006529ACN-122006529-A

Abstract

The invention aims to provide a preparation method of a MOF-based mixed matrix membrane for realizing CO 2 separation under a humid condition through hydrophobic regulation of a pore environment, belongs to the technical field of gas separation, and can solve the problem of separation performance reduction caused by moisture competitive adsorption of the existing mixed matrix membrane under the humid condition. Realizes a CO 2 separation mixed matrix membrane with high performance and moisture resistance, and has good industrial application prospect.

Inventors

  • WANG YONG
  • LI JINPING
  • JIA XIAOXIA
  • WANG LI

Assignees

  • 太原理工大学

Dates

Publication Date
20260512
Application Date
20260320

Claims (10)

  1. 1. A preparation method of a MOF-based mixed matrix membrane for realizing CO 2 separation under a humid condition through hydrophobic regulation of a pore environment is characterized by comprising the following steps: S1, 4' - (hexafluoroisopropyl) phthalic anhydride and 2,4, 6-trimethyl-1, 3-phenylenediamine are dried in a vacuum oven under 423K and 333K respectively for 24 hours, DAM and 6FDA are dissolved in N, N-dimethylacetamide, the mixture is placed in a three-neck flask, the mixture is stirred under a nitrogen atmosphere under 273K by a mechanical stirrer for 24 hours, then acetic anhydride and triethylamine are added, then chemical imidization cyclization reaction is carried out under a nitrogen purge at room temperature for 24 hours, after that, the polyimide solution obtained by the reaction is precipitated by methanol, washed three times by methanol and dried in the vacuum oven under 473K for 24 hours, 6FDA-DAM is obtained, and the prepared 6FDA-DAM is dissolved in an organic solvent to obtain a 6FDA-DAM solution; S2, weighing Zn (NO 3 ) 2 ·6H 2 O and pyrazole-4-carboxylic acid or 3, 5-dimethylpyrazole-4-carboxylic acid ligand, dissolving in N, N-diethylformamide, then adding NaOH, transferring the obtained uniform solution into a stainless steel reaction kettle with a polytetrafluoroethylene lining of 20mL, heating a reaction system at 140 ℃ for 48 hours, naturally cooling to room temperature, centrifugally collecting reaction products, fully washing the reaction products with methanol for 72 hours to remove residual impurities, and then drying at 60 ℃ to obtain Zn-bzc or Zn-bzc-2CH 3 solid products, and dispersing the prepared Zn-bzc or Zn-bzc-2CH 3 in an organic solvent to obtain Zn-bzc or Zn-bzc-2CH 3 dispersion; S3, mixing the 6FDA-DAM solution with the dispersed Zn-bzc or Zn-bzc-2CH 3 solution with different contents, and stirring for 12 hours to obtain a uniformly dispersed casting film solution; S4, pouring the casting solution into a leveled glass culture dish mold after ultrasonic defoaming, and drying in a blast oven for 24 hours to remove the organic solvent to obtain a mixed matrix film; S5, removing the mixed matrix film, and drying in a vacuum oven for 24 hours to remove the organic solvent.
  2. 2. The preparation method of the MOF-based mixed matrix membrane for realizing CO 2 separation under a humid condition through hydrophobic regulation of a pore environment, according to claim 1, wherein in S1, the dosage of 4,4' - (hexafluoroisopropyl) phthalic anhydride and 2,4, 6-trimethyl-1, 3-phenylenediamine is 10mmol, and the dosage of N, N-dimethylacetamide is 25ml.
  3. 3. The preparation method of the MOF-based mixed matrix membrane for realizing CO 2 separation under a humid condition through hydrophobic regulation of a pore environment, which is disclosed in claim 1, is characterized in that in S1, the consumption of acetic anhydride and triethylamine is 5.4mL and 2mL respectively.
  4. 4. The preparation method of the MOF-based mixed matrix membrane for realizing CO 2 separation under a humid condition through hydrophobic regulation of a pore environment, which is disclosed in claim 1, is characterized in that in S1, the organic solvent comprises any one of nitrogen methyl pyrrolidone, N, N-dimethylformamide, chloroform or carbon tetrachloride, and the concentration of the 6FDA-DAM solution is 10wt%.
  5. 5. The method for preparing a MOF-based mixed matrix membrane for CO 2 separation under humid conditions by hydrophobic control in a pore environment according to claim 1, wherein in S2, zn (NO 3 ) 2 ·6H 2 O is used in an amount of 105mg, bzc is used in an amount of 80mg or bzc-2CH 3 ligand is used in an amount of 100mg, and N, N-diethylformamide is used in an amount of 10mL; The NaOH addition amount was 35mg.
  6. 6. The preparation method of the MOF-based mixed matrix membrane for realizing CO 2 separation under a humid condition through hydrophobic regulation of a pore environment, which is disclosed in claim 1, wherein in S2, the organic solvent comprises any one of nitrogen methyl pyrrolidone, N, N-dimethylformamide, chloroform or carbon tetrachloride.
  7. 7. The preparation method of the MOF-based mixed matrix membrane for realizing CO 2 separation under a humid condition through hydrophobic regulation of a pore environment, according to claim 1, wherein the addition amount of Zn-bzc or Zn-bzc-2CH 3 in S2 is 15.8-128.6mg.
  8. 8. The preparation method of the MOF-based mixed matrix membrane for realizing CO 2 separation under a humid condition through hydrophobic regulation and control of a pore environment, which is disclosed in claim 1, wherein in S3, the mass percentage of Zn-bzc or Zn-bzc-2CH 3 in 6FDA-DAM is more than 0 and less than or equal to 30wt%.
  9. 9. The method for preparing the MOF-based mixed matrix membrane for CO 2 separation under the humid condition by hydrophobic regulation of the pore environment according to claim 1, wherein in S4, the temperature of the blast oven is 30 ℃.
  10. 10. The preparation method of the MOF-based mixed matrix membrane for realizing CO 2 separation under a humid condition through hydrophobic regulation of a pore environment, according to claim 1, wherein in S5, the temperature of the vacuum oven is 160 ℃.

Description

Preparation method of MOF-based mixed matrix membrane for realizing CO 2 separation under humid condition through pore environment hydrophobic regulation Technical Field The invention belongs to the technical field of gas separation, and particularly relates to a preparation method of a MOF-based mixed matrix membrane for realizing CO 2 separation under a humid condition through hydrophobic regulation and control of a pore environment. Background CO 2 capture and separation is critical in industrial settings such as flue gas treatment, natural gas purification, and the like. Compared with the traditional processes of low-temperature rectification, chemical absorption and the like, the membrane separation is considered as a potential alternative because of low energy consumption, simple flow, compact equipment and more environment friendliness. Current commercial membranes are based on polymeric membranes, but their performance is limited by the upper Robeson limit, making it difficult to achieve both high permeability and high selectivity. To break this bottleneck, mixed Matrix Membranes (MMMs) have been widely used for CO 2/N2 separation enhancement by introducing porous fillers into the polymer matrix to enhance gas separation efficiency on the basis of processability, wherein Metal Organic Frameworks (MOFs) are distinguished by a designable pore structure, adjustable pore size and functionalizable interface in terms of CO 2 selective adsorption and transport. However, when the device faces to a real working condition, the existence of water vapor is almost unavoidable, the water vapor can preferentially occupy MOF polar sites and pore channels, the adsorption and diffusion of CO 2 are weakened, the selectivity of CO 2 flux and CO 2/N2 is reduced, and even long-term performance degradation is caused. That is, humidity is not only an interference term of experimental conditions, but also a key engineering variable that determines whether the membrane material can land. Therefore, MOF fillers and MMMs for industrial CO 2 capture need to be both hydrothermally stable, inhibit competitive adsorption of water, and still maintain high affinity and efficient transport of CO 2 under humid conditions. In the prior art, the strong hydrophobic MOFs are more water-resistant, but the CO 2 separation performance is possibly sacrificed due to the reduced accessibility of active sites or limited utilization of pore channels, and meanwhile, a systematic solution for performance decay caused by competitive adsorption under wet feed is still insufficient. Therefore, development of a MOF-based mixed matrix membrane material and a preparation strategy capable of stably operating under a humid condition and remarkably inhibiting water vapor competitive adsorption while maintaining high CO 2 permeation and high CO 2/N2 selectivity are needed to meet the actual requirements of industrial CO 2 capture. Disclosure of Invention The invention aims to provide a preparation method of a MOF-based mixed matrix membrane for realizing CO 2 separation under a humid condition through hydrophobic regulation of a pore environment, which selects a zinc-based metal-organic framework Zn-bzc with a cage-shaped pore structure as a parent framework, and introduces a nonpolar methyl substituent group on an organic ligand thereof to obtain methyl functionalized Zn-bzc-2CH 3. Zn-bzc-2CH 3 is used as a porous filler to be dispersed in a polymer matrix to prepare the MOF-based mixed matrix membrane, and the MOF-based mixed matrix membrane shows excellent CO 2 permeation performance and CO 2/N2 separation selectivity under the dry and wet conditions. The invention adopts the following technical scheme: A preparation method of a MOF-based mixed matrix membrane for realizing CO 2 separation under a humid condition through hydrophobic regulation of a pore environment comprises the following steps: S1, 4' - (hexafluoroisopropyl) phthalic anhydride (6 FDA) and 2,4, 6-trimethyl-1, 3-phenylenediamine (DAM) are dried in a vacuum oven under 423K and 333K respectively for 24 hours, DAM and 6FDA are dissolved in N, N-Dimethylacetamide (DMA), the mixture is placed in a three-neck flask, the mixture is stirred under a nitrogen atmosphere under 273K by a mechanical stirrer for 24 hours, then acetic anhydride and triethylamine are added, the chemical imidization reaction is carried out under nitrogen purging at room temperature for 24 hours, after that, the polyimide solution obtained by the reaction is precipitated with methanol, washed three times by methanol, and dried under 473K for 24 hours in the vacuum oven to obtain 6FDA-DAM, and the prepared 6FDA-DAM is dissolved in an organic solvent to obtain 6FDA-DAM solution; s2, weighing Zn (NO 3)2·6H2 O and bzc (pyrazole-4-carboxylic acid) or bzc-2CH 3 (3, 5-dimethylpyrazole-4-carboxylic acid) ligand, dissolving in N, N-Diethylformamide (DEF), then adding NaOH, transferring the obtained uniform solution into a stainless