CN116899420A - Carbon nano tube metal organic frame composite fiber membrane and preparation method and application thereof - Google Patents

Carbon nano tube metal organic frame composite fiber membrane and preparation method and application thereof Download PDF

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CN116899420A
CN116899420A CN202310873813.0A CN202310873813A CN116899420A CN 116899420 A CN116899420 A CN 116899420A CN 202310873813 A CN202310873813 A CN 202310873813A CN 116899420 A CN116899420 A CN 116899420A
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carbon nano
composite fiber
nano tube
metal organic
fiber membrane
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彭婷
丁佰锁
刘华丽
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Qingke Chongqing Advanced Materials Research Institute Co ltd
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Qingke Chongqing Advanced Materials Research Institute Co ltd
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/06—Organic material
    • B01D71/58—Other polymers having nitrogen in the main chain, with or without oxygen or carbon only
    • B01D71/62—Polycondensates having nitrogen-containing heterocyclic rings in the main chain
    • B01D71/64—Polyimides; Polyamide-imides; Polyester-imides; Polyamide acids or similar polyimide precursors
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/22—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by diffusion
    • B01D53/228—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by diffusion characterised by specific membranes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
    • B01D67/0079—Manufacture of membranes comprising organic and inorganic components
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
    • B01D69/08—Hollow fibre membranes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
    • B01D69/12—Composite membranes; Ultra-thin membranes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/02—Inorganic material
    • B01D71/021—Carbon
    • B01D71/0212—Carbon nanotubes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/06—Organic material
    • D—TEXTILES; PAPER
    • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01D—MECHANICAL METHODS OR APPARATUS IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS
    • D01D5/00—Formation of filaments, threads, or the like
    • D01D5/24—Formation of filaments, threads, or the like with a hollow structure; Spinnerette packs therefor
    • D—TEXTILES; PAPER
    • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
    • D01F1/00—General methods for the manufacture of artificial filaments or the like
    • D01F1/02—Addition of substances to the spinning solution or to the melt
    • D01F1/10—Other agents for modifying properties
    • D—TEXTILES; PAPER
    • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
    • D01F6/00—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof
    • D01F6/88—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from mixtures of polycondensation products as major constituent with other polymers or low-molecular-weight compounds
    • D01F6/94—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from mixtures of polycondensation products as major constituent with other polymers or low-molecular-weight compounds of other polycondensation products
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2256/00—Main component in the product gas stream after treatment
    • B01D2256/18—Noble gases

Abstract

The application relates to the technical field of composite fiber membrane materials, in particular to a carbon nano tube metal organic framework composite fiber membrane, a preparation method and application thereof, wherein Zn (NO 3 ) 2 ·6H 2 O and Blm dissolved in dimethylformamideAdding acidified carbon nano tubes into amide, stirring for 30-60 min, heating at 95-120 ℃ for 72-100 h, cooling to room temperature, centrifugally separating, washing with DMF, and drying at 75-85 ℃ for 15-30 h to obtain ZIF-7/CNTs compound; dissolving polyimide in N, N dimethylacetamide, adding ZIF-7/CNTs compound, stirring for 5-8 hours to obtain casting solution, extruding the casting solution through a spinning jet to form hollow fibers, soaking the hollow fibers in deionized water for 36-48 hours, continuously soaking the hollow fibers in ethanol and N-hexane, replacing a soaking solvent every 30 minutes, and finally drying the hollow fibers in a vacuum oven at 60-80 ℃ for 24-48 hours to obtain the composite fiber membrane material. The application combines the metal organic frame material and the carbon nano tube and prepares the composite membrane material with excellent gas permeability and selectivity.

Description

Carbon nano tube metal organic frame composite fiber membrane and preparation method and application thereof
Technical Field
The application relates to the technical field of composite fiber membrane materials, in particular to a carbon nano tube metal organic framework composite fiber membrane, a preparation method and application thereof.
Background
The membrane method gas separation is a novel, efficient and energy-saving separation technology, and has been widely applied to the industrial fields of petrochemical industry, synthetic ammonia and the like. Helium extraction by the membrane method was studied by Stern et al as early as 1965, but the progress of industrialization thereof has been slow so far. Polyimide is used as one of the special engineering plastics with the most excellent performance, and has the advantages of good thermal stability, acid and alkali resistance, solvent resistance, stable molecular size, good mechanical property and the like. Meanwhile, polyimide has good gas selectivity, so polyimide has been attracting attention in the field of gas separation. In order to overcome the restriction relation between gas permeability and selectivity, polymer molecules are modified by various physical and chemical means, such as adding inorganic particles into a polymer system, and the like, in an attempt to prepare a polymer material having both excellent gas permeability and selectivity.
The Metal Organic Frameworks (MOFs) are novel porous structural materials formed by self-assembled coordination connection of one or more metal centers and organic ligands, and the unique 3D structure of the Metal Organic Frameworks (MOFs) enables the metal organic frameworks to have the characteristics of ultrahigh specific surface area, high porosity, controllable morphology and aperture, ordered highly distributed metal active centers, modifiable property and the like, and can form various nano porous carbon metal particles/metal oxides/carbon-based materials with single-atom structures after high-temperature carbonization. The graphitization degree, pore canal maintaining degree and structural integrity degree of different MOFs materials in the carbonization process are very limited, and the further development of MOFs derivative materials in membrane gas separation is restricted. The carbon nanotube material has the characteristics of small size, larger length-diameter ratio and large specific surface area, however, strong van der Waals force and static electricity effect exist among atoms of the carbon nanotube, so that agglomeration phenomenon often occurs to reduce the performance of the material.
Therefore, it is important to study how to combine a metal organic framework material and carbon nanotubes and to prepare a composite membrane material having both excellent gas permeability and selectivity.
Disclosure of Invention
In view of the above, the present application aims to provide a carbon nanotube metal-organic framework composite fiber membrane, a preparation method and an application thereof, which combine a metal-organic framework material with carbon nanotubes and prepare a composite membrane material with excellent gas permeability and selectivity.
The application solves the technical problems by the following technical means:
the first aspect of the application provides a carbon nano tube metal organic frame composite fiber membrane, which is prepared by mixing polyimide and a carbon nano tube metal organic frame composite, spraying and extruding, wherein the weight part of polyimide is 2.1-4.5 parts, and the weight part of the carbon nano tube metal organic frame composite is 0.2-0.8 part.
With reference to the first aspect, in some embodiments, the carbon nanotube metal organic framework composite includes the following raw materials in parts by weight: zn (NO) 3 ) 2 ·6H 2 2.21 to 4.91 portions of O, 1.32 to 4.17 portions of Blm and 1.3 to 2.5 portions of acidified carbon nano-tubes.
The second aspect of the present application provides a method for preparing a carbon nanotube metal-organic framework composite fiber film, comprising the steps of:
zn (NO) 3 ) 2 ·6H 2 Dissolving O and Blm in dimethylformamide, adding acidified carbon nano tubes, stirring for 30-60 min, then transferring into a Teflon stainless steel autoclave, heating for 72-100 h at 95-120 ℃, cooling to room temperature, centrifugally separating, washing with DMF, and drying in a vacuum drying oven at 75-85 ℃ for 15-30 h to obtain a ZIF-7/CNTs compound;
dissolving polyimide in N, N dimethylacetamide, adding ZIF-7/CNTs compound, stirring for 5-8 hours to obtain casting solution, extruding the casting solution through a spinning jet to form hollow fibers, soaking the hollow fibers in deionized water for 36-48 hours, continuously soaking the hollow fibers in ethanol and N-hexane for 2-10 hours, replacing a soaking solvent every 30 minutes, and finally drying the hollow fibers in a vacuum oven at 60-80 ℃ for 24-48 hours to obtain the composite fiber membrane material.
With reference to the second aspect, in some embodiments, the acidified carbon nanotubes are prepared as follows:
adding concentrated sulfuric acid and concentrated nitric acid into the multi-wall carbon nano tube after high temperature treatment in turn, stirring for 4-8 hours at room temperature by ultrasonic wave, diluting the mixed solution, standing until the carbon nano tube is precipitated, pouring out supernatant, filtering the lower suspension by using a polytetrafluoroethylene film with the aperture of 0.22 mu m, repeatedly washing with distilled water until the pH value of the filtrate is approximately equal to 6, and vacuum drying the filtered solid at 55-65 ℃ for 24-48 hours to obtain the acidified carbon nano tube.
With reference to the second aspect, in some embodiments, the high temperature treatment is as follows: the multi-wall carbon nano tube is placed in a closed reaction furnace filled with argon, and the reaction furnace is heated to 1450-1600 ℃ at the heating rate of 10 ℃/min, and then the temperature is kept for 0.8-1.5 h.
With reference to the second aspect, in some embodiments, the volume fraction of the concentrated sulfuric acid is 120-150 parts, and the volume fraction of the concentrated nitric acid is 40-60 parts.
With reference to the second aspect, in some embodiments, the Zn (NO 3 ) 2 ·6H 2 2.21 to 4.91 portions of O, 1.32 to 4.17 portions of Blm and 1.3 to 2.5 portions of acidulated carbon nano tube.
The third aspect of the application provides an application of the carbon nano tube metal organic framework composite fiber membrane in helium separation and purification.
According to the carbon nano tube metal organic frame composite fiber membrane, the growth characteristics of MOFs on the surface of a carbon nano tube are utilized to synthesize the carbon nano tube/metal-organic frame (MOFs) composite material, and the carbon nano tube/metal-organic frame (MOFs) composite material and polyimide are prepared into the hollow fiber membrane together, so that the carbon nano tube metal organic frame composite fiber membrane is obtained, and the composite of MOFs and CNTs can realize multi-aspect complementation and improvement in structure and performance. In the preparation method of the nanotube metal organic framework composite fiber membrane, the carbon nanotubes are acidified, and carboxyl groups are introduced to the surfaces of the multi-wall carbon nanotubes, so that the function modification of the carbon nanotubes, namely the function of providing homogeneous nucleation sites for MOF growth, can be achieved, and small amount of impurities, unreacted carbon particles and the like caused by the limitation of production conditions in the production process can be removed.
The carbon nano tube metal organic framework composite fiber film of the application has higher selection coefficient for helium, and gas detection experimental data show that compared with pure polypropylene, the helium permeability coefficient is improved by 44.16 percent, and the carbon nano tube metal organic framework composite fiber film has higher selection coefficient for helium and higher helium permeability coefficient for He/CH 4 The selectivity coefficient of (C) is improved by 39.29 percent, and the He/N ratio is improved 2 The selection coefficient of (2) is improved by 54.1%.
Drawings
FIG. 1 is a PXRD spectrum for CNTs, ZIF-7/CNTs and ZIF-7 simulations of example 4.
Detailed Description
The technical solutions of the embodiments of the present application will be clearly and completely described in the following in conjunction with the embodiments of the present application, and it is obvious that the described embodiments are only some embodiments of the present application, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.
The following examples were conducted under conventional conditions or conditions recommended by the manufacturer, without specifying the specific conditions. The raw materials, equipment or instruments used are conventional products commercially available without identifying the manufacturer.
The application synthesizes a carbon nano tube/metal-organic frameworks (MOFs) composite material by utilizing the growth characteristic of MOFs on the surface of the carbon nano tube, and prepares the composite material into a hollow fiber membrane together with polyimide, thus obtaining the carbon nano tube metal-organic frameworks composite fiber membrane. The complexing of MOFs and CNTs can achieve multiple-aspect complementation and promotion in structure and performance. The carbon nanotube material has the characteristics of small size, larger length-diameter ratio and large specific surface area, however, strong van der Waals force and static electricity effect exist among atoms of the carbon nanotube, so that agglomeration phenomenon often occurs to reduce the performance of the material. Therefore, in order to prepare the mixed matrix film with excellent performance, the carbon nano tube is subjected to functional modification, so that the carbon nano tube and the polymer matrix have certain interaction. By acidifying the carbon nano tube and introducing carboxyl to the surface of the multi-wall carbon nano tube, the function of functional modification of the carbon nano tube, which provides a homogeneous nucleation site for MOF growth, can be achieved, and a small amount of impurities, unreacted carbon particles and the like caused by the limitation of production conditions in the production process can be removed.
The carbon nano tube metal organic frame composite fiber membrane is prepared by mixing polyimide and a carbon nano tube metal organic frame composite, spinning and extruding, wherein the weight part of polyimide is 2.1-4.5 parts, and the weight part of the carbon nano tube metal organic frame composite is 0.2-0.8 part. The preparation method comprises the following steps:
2.21 to 4.91 parts by weight of Zn (NO) 3 ) 2 ·6H 2 Dissolving O and Blm with the mass portion of 1.32-4.17 in dimethylformamide, adding acidified carbon nano tubes, stirring for 30-60 min, then transferring into a Teflon stainless steel autoclave, heating for 72-100 h at 95-120 ℃, cooling to room temperature, centrifuging, separating, washing with DMF, and drying for 15-30 h at 75-85 ℃ in a vacuum drying oven to obtain a ZIF-7/CNTs compound;
dissolving polyimide in N, N dimethylacetamide, adding ZIF-7/CNTs compound, stirring for 5-8 hours to obtain casting solution, extruding the casting solution through a spinning jet to form hollow fibers, soaking the hollow fibers in deionized water for 36-48 hours, continuously soaking the hollow fibers in ethanol and N-hexane for 2-10 hours, replacing a soaking solvent every 30 minutes, and finally drying the hollow fibers in a vacuum oven at 60-80 ℃ for 24-48 hours to obtain the composite fiber membrane material.
Example 1
The preparation method of the carbon nanotube metal organic framework composite fiber membrane of the embodiment is as follows:
(1) Modification of carbon nanotubes
Argon is used as shielding gas, the flow is 150seem, the heating rate is 10 ℃/min, and the post treatment is carried out for 1h at 1500 ℃. Weighing 2.0g of high-temperature annealed multi-wall carbon nano tube (p-MWCNT) in a 250mL three-necked bottle, sequentially adding 120mL of concentrated sulfuric acid and 40mL of concentrated nitric acid, stirring for 5h at room temperature by ultrasonic, diluting the mixed solution, slowly pouring into a 5000mL beaker, standing until the carbon nano tube precipitates, pouring out supernatant, filtering the lower suspension by using a polytetrafluoroethylene film with the pore diameter of 0.22 mu m, repeatedly washing by using distilled water until the pH of filtrate is approximately equal to 6, filtering, and then drying in vacuum at 60 ℃ for 24h to obtain the acidified carbon nano tube (c-MWCNT).
(2) Synthesis of ZIF-7/CNTs composite materials
2.43g Zn (NO) 3 ) 2 ·6H 2 O and 1.49g of Blm are dissolved in 300ml of DMF, 1.5g of modified c-MWCNT is added after stirring for 30min, stirring is continued for 30min, then the solution is transferred into a Teflon stainless steel autoclave, and is heated for 72h at 100 ℃, ZIF-7 is obtained by centrifugal separation after cooling to room temperature, and is dried for 15h at 80 ℃ in a vacuum drying oven after washing 3 times with DMF, thus obtaining the ZIF-7/CNTs composite material.
(3) Hollow fiber membrane prepared from ZIF-7/CNTs and PI
Dissolving 2.8g of PI in 50ml of DMAc, stirring for several hours, adding 0.2g of ZIF-7/CNTs, continuously stirring for 5 hours to obtain a casting solution, extruding the casting solution through a spinning jet to form hollow fibers, wherein a volatile solvent evaporates at the outermost layer of the fibers to form a primary ultrathin selection layer; the fibrils are stretched in the air gap and then enter a tap water bath to form a porous network under the cortex; collecting the hollow fiber, soaking in deionized water for 36h to remove residual solvent and non-solvent in the fiber, continuously soaking in ethanol and n-hexane for 2h, replacing the solvent every 30min, and finally drying the hollow fiber in a vacuum oven at 60 ℃ for 24h to obtain the final hollow fiber membrane material.
Example 2
The preparation method of the carbon nanotube metal organic framework composite fiber membrane of the embodiment is as follows:
(1) Modification of carbon nanotubes
Argon is used as shielding gas, the flow is 150seem, the heating rate is 10 ℃/min, and the post treatment is carried out for 1h at 1500 ℃. Weighing 3.0g of high-temperature annealed multi-wall carbon nano tube (p-MWCNT) in a 250mL three-necked bottle, sequentially adding 135mL of concentrated sulfuric acid and 45mL of concentrated nitric acid, stirring for 6h at room temperature by ultrasonic, diluting the mixed solution, slowly pouring into a 5000mL beaker, standing until the carbon nano tube precipitates, pouring out supernatant, filtering the lower suspension by using a polytetrafluoroethylene film with the pore diameter of 0.22 mu m, repeatedly washing by using distilled water until the pH of filtrate is approximately equal to 6, filtering, and then drying in vacuum at 60 ℃ for 36h to obtain the acidified carbon nano tube (c-MWCNT).
(2) Synthesis of ZIF-7/CNTs composite materials
3.54g Zn (NO) 3 ) 2 ·6H 2 O and 2.96g of Blm are dissolved in 400ml of DMF, 2.5g of modified c-MWCNT is added after stirring for 45min, stirring is continued for 60min, then the solution is transferred into a Teflon stainless steel autoclave, heating is carried out for 96h at 100 ℃, ZIF-7 is obtained through centrifugal separation after cooling to room temperature, and ZIF-7 is obtained after washing for several times by DMF, and the ZIF-7/CNTs composite material is obtained after drying in a vacuum drying oven at 80 ℃.
(3) Preparation of ZIF-7/CNTs and PI composite film:
dissolving 2.5g of PI in 100ml of DMAc, stirring for several hours, adding 0.5g of ZIF-7/CNTs, continuously stirring for 8 hours to obtain a casting solution, extruding the casting solution through a spinning jet to form hollow fibers, wherein a volatile solvent evaporates at the outermost layer of the fibers to form a primary ultrathin selection layer; the fibrils are stretched in the air gap and then enter a tap water bath to form a porous network under the cortex; collecting the hollow fiber, soaking in deionized water for 48h to remove residual solvent and non-solvent in the fiber, continuously soaking in ethanol and n-hexane for 10h, replacing the solvent every 30min, and finally drying the hollow fiber in a vacuum oven at 80 ℃ for 48h to obtain the final hollow fiber membrane material.
Example 3
The preparation method of the carbon nanotube metal organic framework composite fiber membrane of the embodiment is as follows:
(1) Modification of carbon nanotubes
Argon is used as shielding gas, the flow is 150seem, the heating rate is 10 ℃/min, and the post treatment is carried out for 1h at 1500 ℃. Weighing 3.5g of high-temperature annealed multi-wall carbon nano tube (p-MWCNT) in a 250mL three-necked bottle, sequentially adding 150mL of concentrated sulfuric acid and 50mL of concentrated nitric acid, stirring for 4h at room temperature by ultrasonic, diluting the mixed solution, slowly pouring into a 5000mL beaker, standing until the carbon nano tube precipitates, pouring out supernatant, filtering the lower suspension by using a polytetrafluoroethylene film with the pore diameter of 0.22 mu m, repeatedly washing by using distilled water until the pH of filtrate is approximately equal to 6, filtering, and then drying in vacuum at 60 ℃ for 48h to obtain the acidified carbon nano tube (c-MWCNT).
(2) Synthesis of ZIF-7/CNTs composite materials
2.21g Zn (NO) 3 ) 2 ·6H 2 O and 1.32g of Blm are dissolved in 350ml of DMF, 1.3g of modified c-MWCNT is added after stirring for 40min, stirring is continued for 40min, then the solution is transferred into a Teflon stainless steel autoclave, and is heated for 100h at 100 ℃, ZIF-7 is obtained by centrifugal separation after cooling to room temperature, and is dried for 20h at 80 ℃ in a vacuum drying oven after washing 3 times with DMF, thus obtaining the ZIF-7/CNTs composite material.
(3) Hollow fiber membrane prepared from ZIF-7/CNTs and PI
Dissolving 2.1g of PI in 50ml of DMAc, stirring for several hours, adding 0.4g of ZIF-7/CNTs, continuously stirring for 6 hours to obtain a casting solution, extruding the casting solution through a spinning jet to form hollow fibers, wherein a volatile solvent evaporates at the outermost layer of the fibers to form a primary ultrathin selection layer; the fibrils are stretched in the air gap and then enter a tap water bath to form a porous network under the cortex; collecting the hollow fiber, soaking in deionized water for 40h to remove residual solvent and non-solvent in the fiber, continuously soaking in ethanol and n-hexane for 5h, replacing the solvent every 30min, and finally drying the hollow fiber in a vacuum oven at 70 ℃ for 24h to obtain the final hollow fiber membrane material.
Example 4
The preparation method of the carbon nanotube metal organic framework composite fiber membrane of the embodiment is as follows:
(1) Modification of carbon nanotubes
Argon is used as shielding gas, the flow is 150seem, the heating rate is 10 ℃/min, and the post treatment is carried out for 1h at 1500 ℃. Weighing 3.0g of high-temperature annealed multi-wall carbon nano tube (p-MWCNT) in a 250mL three-necked bottle, sequentially adding 125mL of concentrated sulfuric acid and 60mL of concentrated nitric acid, stirring for 8h at room temperature by ultrasonic, diluting the mixed solution, slowly pouring into a 5000mL beaker, standing until the carbon nano tube precipitates, pouring out supernatant, filtering the lower suspension by using a polytetrafluoroethylene film with the pore diameter of 0.22 mu m, repeatedly washing by using distilled water until the pH of filtrate is approximately equal to 6, filtering, and then vacuum drying at 60 ℃ for 40h to obtain the acidified carbon nano tube (c-MWCNT).
(2) Synthesis of ZIF-7/CNTs composite materials
4.91g Zn (NO) 3 ) 2 ·6H 2 O and 4.17g of Blm are dissolved in 400ml of DMF, 2.0g of modified c-MWCNT is added after stirring for 60min, stirring is continued for 50min, then the solution is transferred into a Teflon stainless steel autoclave, and is heated for 80h at 100 ℃, ZIF-7 is obtained by centrifugal separation after cooling to room temperature, and is dried for 25h at 80 ℃ in a vacuum drying oven after washing for several times with DMF, thus obtaining the ZIF-7/CNTs composite material.
(3) Preparation of ZIF-7/CNTs and PI composite film:
dissolving 4.5g of PI in 100ml of DMAc, stirring for several hours, adding 0.8g of ZIF-7/CNTs, continuously stirring for 8 hours to obtain a casting solution, extruding the casting solution through a spinning jet to form hollow fibers, wherein a volatile solvent evaporates at the outermost layer of the fibers to form a primary ultrathin selection layer; the fibrils are stretched in the air gap and then enter a tap water bath to form a porous network under the cortex; collecting hollow fibers, soaking in deionized water for 48h to remove residual solvent and non-solvent in the fibers, continuously soaking in ethanol and n-hexane for 10h, replacing the solvent every 30min, and finally drying the hollow fibers in a vacuum oven at 80 ℃ for 48h to obtain the final hollow fiber membrane material, wherein the PXRD spectrum is shown in figure 1.
FIG. 1 is a PXRD spectrum for CNTs, ZIF-7/CNTs and ZIF-7 simulations of example 4.
The carbon nanotube metal organic frame composite fiber membranes prepared in examples 1 to 4 were subjected to gas permeability test, and the carbon nanotube metal organic frame composite fiber membranes prepared in examples 1 to 4 were subjected to gas permeability and separation performance evaluation by a constant volume pressure method at room temperature using a pure polypropylene hollow fiber membrane as a control group, and were testedThe gas pair is He, CH 4 And N 2 . The test results are shown in table 1:
TABLE 1
Examples Helium permeability coefficient (bar) For He/CH 4 Is a coefficient of selection of (2) For He/N 2 Is a coefficient of selection of (2)
Example 1 161 99 167
Example 2 170 117 184
Example 3 167 113 181
Example 4 173 112 188
Pure polypropylene 120 84 122
The data in Table 1 shows that the carbon nanotube metal organic framework composite fiber membrane of the application has higher selectivity coefficient for helium, and compared with pure polypropylene, the helium permeability coefficient is improved by 44.16%, and the carbon nanotube metal organic framework composite fiber membrane has higher selectivity coefficient for helium and higher helium permeability than pure polypropylene, and has higher helium permeability than pure polypropylene 4 The selectivity coefficient of (C) is improved by 39.29 percent, and the He/N ratio is improved 2 The selectivity coefficient of the carbon nano tube metal organic framework composite fiber film is improved by 54.1 percent, so that the carbon nano tube metal organic framework composite fiber film can be used for separating and purifying helium.
The above embodiments are only for illustrating the technical solution of the present application and not for limiting the same, and although the present application has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications and equivalents may be made thereto without departing from the spirit and scope of the technical solution of the present application, which is intended to be covered by the scope of the claims of the present application. The technology, shape, and construction parts of the present application, which are not described in detail, are known in the art.

Claims (8)

1. The carbon nano tube metal organic frame composite fiber membrane is characterized in that the composite fiber membrane is prepared by mixing polyimide and a carbon nano tube metal organic frame composite, spraying and extruding, wherein the weight portion of polyimide is 2.1-4.5 portions, and the weight portion of the carbon nano tube metal organic frame composite is 0.2-0.8 portion.
2. The carbon nanotube metal organic framework composite fiber membrane of claim 1, wherein the carbon nanotube metal organic framework composite comprises the following raw materials in parts by weight: zn (NO) 3 ) 2 ·6H 2 2.21 to 4.91 portions of O, 1.32 to 4.17 portions of Blm, and 1.3 to 2.5 portions of acidified carbon nano-tubes.
3. The preparation method of the carbon nano tube metal organic frame composite fiber membrane is characterized by comprising the following steps of:
zn (NO) 3 ) 2 ·6H 2 Dissolving O and Blm in dimethylformamide, adding acidified carbon nano tubes, stirring for 30-60 min, then transferring into an autoclave, heating at 95-120 ℃ for 72-100 h, cooling to room temperature, centrifugally separating, washing with DMF, and drying at 75-85 ℃ for 15-30 h in a vacuum drying oven to obtain ZIF-7/CNTs compound;
dissolving polyimide in N, N dimethylacetamide, adding ZIF-7/CNTs compound, stirring for 5-8 hours to obtain casting solution, extruding the casting solution through a spinning jet to form hollow fibers, soaking the hollow fibers in deionized water for 36-48 hours, continuously soaking the hollow fibers in ethanol and N-hexane for 2-10 hours, replacing a soaking solvent every 30 minutes, and finally drying the hollow fibers in a vacuum oven at 60-80 ℃ for 24-48 hours to obtain the composite fiber membrane material.
4. The method for preparing a carbon nanotube metal organic framework composite fiber film according to claim 3, wherein the preparation of the acidified carbon nanotubes is as follows:
adding concentrated sulfuric acid and concentrated nitric acid into the multi-wall carbon nano tube after high temperature treatment in turn, stirring for 4-8 hours at room temperature by ultrasonic wave, diluting the mixed solution, standing until the carbon nano tube is precipitated, pouring out supernatant, filtering the lower suspension by using a polytetrafluoroethylene film with the aperture of 0.22 mu m, repeatedly washing with distilled water until the pH value of the filtrate is approximately equal to 6, and vacuum drying the filtered solid at 55-65 ℃ for 24-48 hours to obtain the acidified carbon nano tube.
5. The method for preparing a carbon nanotube metal organic framework composite fiber film according to claim 4, wherein the high temperature treatment is as follows: the multi-wall carbon nano tube is placed in a closed reaction furnace filled with argon, and the reaction furnace is heated to 1450-1600 ℃ at the heating rate of 10 ℃/min, and then the temperature is kept for 0.8-1.5 h.
6. The method for preparing a carbon nanotube metal-organic framework composite fiber membrane according to claim 5, wherein the concentrated sulfuric acid is 120-150 parts by volume and the concentrated nitric acid is 40-60 parts by volume.
7. The method for producing a carbon nanotube metal-organic framework composite fiber film according to claim 3, wherein the Zn (NO 3 ) 2 ·6H 2 2.21 to 4.91 portions of O, 1.32 to 4.17 portions of Blm and 1.3 to 2.5 portions of acidulated carbon nano tube.
8. Use of the carbon nanotube metal organic framework composite fiber membrane according to claim 1 or 2 or the carbon nanotube metal organic framework composite fiber membrane prepared by the preparation method according to any one of claims 3 to 7 in helium separation and purification.
CN202310873813.0A 2023-07-17 2023-07-17 Carbon nano tube metal organic frame composite fiber membrane and preparation method and application thereof Pending CN116899420A (en)

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