CN117358073A - Gas separation membrane and preparation method and application thereof - Google Patents
Gas separation membrane and preparation method and application thereof Download PDFInfo
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- CN117358073A CN117358073A CN202210770916.XA CN202210770916A CN117358073A CN 117358073 A CN117358073 A CN 117358073A CN 202210770916 A CN202210770916 A CN 202210770916A CN 117358073 A CN117358073 A CN 117358073A
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- 238000000926 separation method Methods 0.000 title claims abstract description 119
- 239000012528 membrane Substances 0.000 title claims abstract description 116
- 238000002360 preparation method Methods 0.000 title abstract description 14
- 230000035699 permeability Effects 0.000 claims abstract description 25
- 239000011148 porous material Substances 0.000 claims abstract description 22
- 239000004693 Polybenzimidazole Substances 0.000 claims description 68
- 229920002480 polybenzimidazole Polymers 0.000 claims description 68
- 229920006254 polymer film Polymers 0.000 claims description 37
- 238000002791 soaking Methods 0.000 claims description 28
- 239000003960 organic solvent Substances 0.000 claims description 26
- 238000005266 casting Methods 0.000 claims description 25
- 238000000034 method Methods 0.000 claims description 25
- 239000003795 chemical substances by application Substances 0.000 claims description 18
- 239000003361 porogen Substances 0.000 claims description 18
- ZMXDDKWLCZADIW-UHFFFAOYSA-N N,N-Dimethylformamide Chemical compound CN(C)C=O ZMXDDKWLCZADIW-UHFFFAOYSA-N 0.000 claims description 15
- 239000004642 Polyimide Substances 0.000 claims description 14
- 229920001721 polyimide Polymers 0.000 claims description 14
- FXHOOIRPVKKKFG-UHFFFAOYSA-N N,N-Dimethylacetamide Chemical compound CN(C)C(C)=O FXHOOIRPVKKKFG-UHFFFAOYSA-N 0.000 claims description 13
- 239000000758 substrate Substances 0.000 claims description 13
- 239000007787 solid Substances 0.000 claims description 12
- 239000002253 acid Substances 0.000 claims description 11
- IAZDPXIOMUYVGZ-UHFFFAOYSA-N Dimethylsulphoxide Chemical compound CS(C)=O IAZDPXIOMUYVGZ-UHFFFAOYSA-N 0.000 claims description 10
- 239000007788 liquid Substances 0.000 claims description 9
- 230000005588 protonation Effects 0.000 claims description 7
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 claims description 6
- 238000004519 manufacturing process Methods 0.000 claims description 6
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 claims description 5
- 238000002156 mixing Methods 0.000 claims description 5
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 4
- AFVFQIVMOAPDHO-UHFFFAOYSA-N Methanesulfonic acid Chemical compound CS(O)(=O)=O AFVFQIVMOAPDHO-UHFFFAOYSA-N 0.000 claims description 4
- 229920002492 poly(sulfone) Polymers 0.000 claims description 4
- 239000004695 Polyether sulfone Substances 0.000 claims description 3
- 229920006393 polyether sulfone Polymers 0.000 claims description 3
- 238000007790 scraping Methods 0.000 claims description 3
- 229920003171 Poly (ethylene oxide) Polymers 0.000 claims description 2
- 239000004697 Polyetherimide Substances 0.000 claims description 2
- 229920001601 polyetherimide Polymers 0.000 claims description 2
- 239000007789 gas Substances 0.000 description 99
- 238000001035 drying Methods 0.000 description 22
- 239000002904 solvent Substances 0.000 description 9
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 8
- 229910052739 hydrogen Inorganic materials 0.000 description 7
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 6
- 230000000052 comparative effect Effects 0.000 description 6
- 238000005516 engineering process Methods 0.000 description 6
- 239000001257 hydrogen Substances 0.000 description 6
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 5
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 5
- 238000001816 cooling Methods 0.000 description 5
- 238000005530 etching Methods 0.000 description 5
- 239000012510 hollow fiber Substances 0.000 description 5
- 239000011248 coating agent Substances 0.000 description 4
- 238000000576 coating method Methods 0.000 description 4
- 239000008367 deionised water Substances 0.000 description 4
- 229910021641 deionized water Inorganic materials 0.000 description 4
- 229910052734 helium Inorganic materials 0.000 description 4
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 4
- 238000005191 phase separation Methods 0.000 description 4
- 238000003756 stirring Methods 0.000 description 4
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 3
- 238000010521 absorption reaction Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 238000001914 filtration Methods 0.000 description 3
- 239000004088 foaming agent Substances 0.000 description 3
- 239000011521 glass Substances 0.000 description 3
- 239000001307 helium Substances 0.000 description 3
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 description 3
- 239000010410 layer Substances 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 239000002105 nanoparticle Substances 0.000 description 3
- 229910052763 palladium Inorganic materials 0.000 description 3
- 229920000642 polymer Polymers 0.000 description 3
- 238000000746 purification Methods 0.000 description 3
- 238000005406 washing Methods 0.000 description 3
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 description 2
- LRHPLDYGYMQRHN-UHFFFAOYSA-N N-Butanol Chemical compound CCCCO LRHPLDYGYMQRHN-UHFFFAOYSA-N 0.000 description 2
- WPYMKLBDIGXBTP-UHFFFAOYSA-N benzoic acid Chemical compound OC(=O)C1=CC=CC=C1 WPYMKLBDIGXBTP-UHFFFAOYSA-N 0.000 description 2
- 229920002301 cellulose acetate Polymers 0.000 description 2
- 238000005261 decarburization Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 239000004205 dimethyl polysiloxane Substances 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 239000003345 natural gas Substances 0.000 description 2
- 229920000435 poly(dimethylsiloxane) Polymers 0.000 description 2
- -1 polydimethylsiloxane Polymers 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 238000012876 topography Methods 0.000 description 2
- 238000009423 ventilation Methods 0.000 description 2
- RNFJDJUURJAICM-UHFFFAOYSA-N 2,2,4,4,6,6-hexaphenoxy-1,3,5-triaza-2$l^{5},4$l^{5},6$l^{5}-triphosphacyclohexa-1,3,5-triene Chemical compound N=1P(OC=2C=CC=CC=2)(OC=2C=CC=CC=2)=NP(OC=2C=CC=CC=2)(OC=2C=CC=CC=2)=NP=1(OC=1C=CC=CC=1)OC1=CC=CC=C1 RNFJDJUURJAICM-UHFFFAOYSA-N 0.000 description 1
- 239000005711 Benzoic acid Substances 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 239000002250 absorbent Substances 0.000 description 1
- 230000002745 absorbent Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 235000010233 benzoic acid Nutrition 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 238000007664 blowing Methods 0.000 description 1
- 238000010668 complexation reaction Methods 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 229920006351 engineering plastic Polymers 0.000 description 1
- 239000004744 fabric Substances 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 239000000945 filler Substances 0.000 description 1
- 239000003063 flame retardant Substances 0.000 description 1
- 238000001891 gel spinning Methods 0.000 description 1
- 125000000623 heterocyclic group Chemical group 0.000 description 1
- 150000002431 hydrogen Chemical class 0.000 description 1
- 125000002883 imidazolyl group Chemical group 0.000 description 1
- 238000004377 microelectronic Methods 0.000 description 1
- 238000001728 nano-filtration Methods 0.000 description 1
- 239000011368 organic material Substances 0.000 description 1
- 239000004417 polycarbonate Substances 0.000 description 1
- 229920000515 polycarbonate Polymers 0.000 description 1
- 239000002861 polymer material Substances 0.000 description 1
- 229920001343 polytetrafluoroethylene Polymers 0.000 description 1
- 239000004810 polytetrafluoroethylene Substances 0.000 description 1
- 230000001681 protective effect Effects 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 238000001223 reverse osmosis Methods 0.000 description 1
- 150000003384 small molecules Chemical class 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 239000002344 surface layer Substances 0.000 description 1
- 238000000108 ultra-filtration Methods 0.000 description 1
Classifications
-
- 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
-
- 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
- B01D67/0002—Organic membrane manufacture
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Engineering & Computer Science (AREA)
- Analytical Chemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Manufacturing & Machinery (AREA)
- Separation Using Semi-Permeable Membranes (AREA)
Abstract
The invention relates to the technical field of membrane separation, and discloses a gas separation membrane, and a preparation method and application thereof. The gas separation membrane has a cross-transmission network-shaped pore structure, so that the gas separation membrane has higher gas selectivity and permeability coefficient at the same time, and can realize He/N 2 、He/CH 4 、H 2 /CO 2 、H 2 /N 2 、H 2 /CH 4 、CO 2 /N 2 、CO 2 /CH 4 High selectivity separation of the gas pairs.
Description
Technical Field
The invention relates to the technical field of membrane separation, in particular to a gas separation membrane, and a preparation method and application thereof.
Background
The gas membrane separation is a green technology, and compared with the traditional separation technologies such as adsorption, absorption, cryogenic separation and the like, the membrane separation technology has the advantages of high separation efficiency, low energy consumption, simplicity in operation and the like, is a mainstream technology for gas separation in the future, and has wide application prospects in the fields of natural gas helium removal, hydrogen purification, decarburization and the like.
The gas separation membrane may be classified into an organic membrane, an inorganic membrane, and an organic-inorganic hybrid membrane based on the difference in materials of the gas separation membrane. The organic membrane is the most attractive material in the gas separation membrane industry due to the characteristics of various preparation materials, simple manufacturing method, good processing performance, easy mass production, good mechanical stability and the like. Currently, organic materials such as Polyimide (PI), cellulose Acetate (CA), polysulfone (PS), polycarbonate (PC), polydimethylsiloxane (PDMS), polybenzimidazole and the like have been developed and applied to the preparation of gas separation membranes.
Polybenzimidazole (PBI) is a heterocyclic polymer with an imidazole ring-containing main chain, is an advanced engineering plastic, has good mechanical stability, thermal stability and chemical stability, and has important application in the fields of high-temperature resistant filter fabrics, flame-retardant protective clothing, aerospace clothing, aircraft interiors, fireproof fillers, microelectronics and separation membranes. In the field of separation membranes, PBI can be used for preparing reverse osmosis membranes, ultrafiltration membranes, nanofiltration membranes, proton exchange membranes and gas separation membranes. The advantages are particularly evident in severe operating environments. The rigidity of PBI molecular chain and the existence of intermolecular hydrogen bond can well separate small molecular gas, and He/N can be realized 2 、He/CH 4 、H 2 /CO 2 、H 2 /N 2 、H 2 /CH 4 、CO 2 /N 2 、CO 2 /CH 4 Separation of the gas pairs. But the gas permeability coefficient of PBI is small and needs to be further improved, and an effective improvement method is to prepare a porous membrane. The most common method for preparing the PBI porous gas separation membrane at present is non-solvent induced phase separation, and the prepared pore structure is a spongy pore or a finger-shaped pore.
Document (Highly selective asymmetric polybenzimidazole-4,4' - (hexafluorous profolidene) bis (benzoic acid) hollow fiber membranes for hydrogen separation) reports a method for preparing a PBI hollow fiber gas separation membrane by dry-wet spinning, wherein the prepared hollow fiber membrane is in the form of a finger-shaped pore, and the membrane is prepared under optimal conditions, and H is 2 /N 2 、H 2 /CO 2 And CO 2 /N 2 The separation properties of (2) are only 43.4, 2.52 and 17.2, and the separation properties of the small molecule gas are not good. Document (Fabrication of Polybenzimidazole/Palladium Nanoparticles Hollow Fiber Membranes for Hydrogen Purification) reports a method for preparing a PBI/palladium nanoparticle double-layer hollow fiber membrane by a method of non-solvent induced phase separation combined with complexation induced phase separation, and although the final double-sided composite membrane shows good hydrogen permeability and selectivity, the expensive palladium nanoparticle layer mainly plays a role in transporting and separating hydrogen.
The PBI porous gas separation membrane prepared by the prior art has low selectivity, a compact layer is required to be coated on the surface layer of the PBI porous membrane to enhance the selectivity, and the preparation process is complex. The present invention has been made in an effort to provide a new method for preparing a PBI porous membrane, which improves gas permeability while maintaining high selectivity of PBI.
Disclosure of Invention
The invention aims to solve the problems of poor separation selectivity, low gas permeability coefficient and low permeability coefficient of a separation membrane in the prior art, and provides a gas separation membrane, a preparation method and application thereof.
In order to achieve the above object, a first aspect of the present invention provides a gas separation membrane, characterized in that the gas separation membrane has a cross-transfer network-like pore structure.
In a second aspect, the present invention provides a method for producing a gas separation membrane, comprising:
s1, scraping and casting a film casting solution containing polybenzimidazole and a pore-forming agent on a substrate to form a film, and separating the film from the substrate to obtain a polymer film;
s2, carrying out protonation treatment on the polymer film to obtain a protonated polymer film;
s3, removing the pore-forming agent from the protonic polymer film to obtain the gas separation film;
wherein the mass ratio of the polybenzimidazole to the porogen is 3:7-9:1.
In a third aspect, the present invention provides a gas separation membrane prepared by the preparation method provided in the second aspect.
A fourth aspect of the present invention provides a gas separation membrane according to the first aspect of the present invention and the use of a gas separation membrane according to the third aspect of the present invention in gas separation.
Through the technical scheme, the gas separation membrane provided by the invention and the preparation method and application thereof have the following beneficial effects:
(1) The gas separation membrane has a cross-transfer network-shaped pore structure, so that the gas separation membrane has higher gas selectivity and permeability coefficient at the same time, and can realize He/N 2 、He/CH 4 、H 2 /CO 2 、H 2 /N 2 、H 2 /CH 4 、CO 2 /N 2 、CO 2 /CH 4 High selectivity separation of the gas pairs.
(2) The preparation method comprises the steps of blending the polybenzimidazole with the pore-forming agent of the high polymer material to prepare a polymer film, so that the first solvent is favorable for protonating the polybenzimidazole and changing the solubility of the polybenzimidazole, and etching the pore-forming agent in the polymer film by using the second solvent to prepare the polybenzimidazole film with the cross-transmission network pore structure, namely the gas separation film, wherein the structure formed by the polybenzimidazole component is not damaged in the etching process by carrying out the protonation treatment on the polybenzimidazole component in the mixed film, so that the gas separation film is ensured to have the cross-transmission network pore structure, and the gas separation film has higher gas selectivity and permeability coefficient.
(3) The preparation method is simple and convenient to operate, is easy to carry out industrialized implementation, and can be used in the fields of helium gas and hydrogen gas purification and natural gas decarburization.
Drawings
FIG. 1 is a surface topography of a gas separation membrane prepared in example 4;
FIG. 2 is a cross-sectional view of the gas separation membrane produced in example 4.
Detailed Description
The endpoints and any values of the ranges disclosed herein are not limited to the precise range or value, and are understood to encompass values approaching those ranges or values. For numerical ranges, one or more new numerical ranges may be found between the endpoints of each range, between the endpoint of each range and the individual point value, and between the individual point value, in combination with each other, and are to be considered as specifically disclosed herein.
The first aspect of the present invention provides a gas separation membrane, wherein the gas separation membrane has a cross-transfer network-like pore structure.
In the invention, the gas separation membrane has a cross-transmission network-shaped pore structure, and the cross-transmission network-shaped pore structure can maintain and even further improve the gas selection of the gas separation membrane on the premise of improving the permeability coefficient of the gas separation membrane, and especially can realize He/N 2 、He/CH 4 、H 2 /CO 2 、H 2 /N 2 、H 2 /CH 4 、CO 2 /N 2 、CO 2 /CH 4 High selectivity separation of the gas pairs.
According to the invention, the porosity of the gas separation membrane is 10-70%.
In the present invention, the porosity of the gas separation membrane satisfies the above range, and the permeability coefficient of the gas separation membrane can be further improved.
Further, the gas separation membrane has a porosity of 17 to 50%.
According to the invention, the gas separation membrane has a permeability coefficient of 9-30Barrer.
In the present invention, when the permeability coefficient satisfies the above range, the gas separation membrane can be ensured to have a higher gas selectivity at the same time as the permeability coefficient.
According to the invention, the gas separation membrane has a permeability coefficient of 9-15Barrer.
In the present invention, when the permeability coefficient satisfies the above range, the selective separation of the gas by the gas separation membrane can be further improved.
In a second aspect, the present invention provides a method for producing a gas separation membrane, comprising:
s1, scraping and casting a film casting solution containing polybenzimidazole and a pore-forming agent on a substrate to form a film, and separating the film from the substrate to obtain a polymer film;
s2, carrying out protonation treatment on the polymer film to obtain a protonated polymer film;
s3, removing the pore-forming agent from the protonic polymer film to obtain the gas separation film;
the mass ratio of the polybenzimidazole to the porogen is 3:7-9:1.
In the present invention, the inventors have found that the current method for preparing a PBI porous membrane is mainly non-solvent induced phase separation, resulting in a membrane with higher permeability but poor selectivity. The invention provides a brand new method: solvent etching. The gas transmission channel with the cross-transmission network-shaped pore structure is etched in the dense PBI membrane by utilizing the solvent, so that the gas separation membrane has the characteristics of high selectivity separation performance and high permeability coefficient.
In the invention, the mass ratio of the polybenzimidazole to the pore-forming agent satisfies the above range, so that the gas separation membrane can ensure high separation selectivity and improve the permeability of the gas separation membrane.
Furthermore, the method is simple and convenient to prepare, the process is stable, the pore structure of the polybenzimidazole can be regulated and controlled by changing the types, the molecular weight and the addition proportion of the pore-foaming agent, and the industrial implementation is easy to develop.
In the present invention, the substrate is not particularly limited, and may be a substrate conventionally used in the art, for example, a glass plate, a steel plate, a polytetrafluoroethylene plate, or the like.
In the present invention, the plate-membrane separation may be performed by: the substrate coated with the casting solution is dried and then immersed in water to peel the film from the surface of the substrate, thereby achieving plate-film separation.
Further, the drying means and conditions may be conventional means in the art, and in the present invention, drying is preferably performed at 70 to 200℃for 2 to 8 hours.
The inventor of the present invention has found through research that a better technical effect can be obtained by first drying a substrate coated with a casting solution at normal pressure and 70-110 ℃ and then performing second drying at a vacuum degree of-0.1 MPa to 0MPa and 110-200 ℃.
According to the invention, the mass ratio of the polybenzimidazole to the porogen is 1-9:1.
the polybenzimidazole comprises a structural unit represented by formula (1):
wherein R1 is selected from structural units shown in formula a, formula b, formula c or formula d;
in the present invention, the inventors have found that when the polybenzimidazole contains a structural unit represented by formula (1), the viscosity of the resulting casting solution can meet the coating requirement, coating is easy, and the mechanical properties of the prepared PBI porous membrane are good.
According to the invention, the method further comprises: and mixing and defoaming the polybenzimidazole, the pore-forming agent and the first organic solvent to obtain the casting solution.
In the present invention, there are no particular requirements on the manner and conditions of the mixing, the dissolving and the deaeration, and they may be conventional in the art. Preferably, the mixing conditions include: stirring at 40-80deg.C for 24-72 hr.
Further, the defoaming may be centrifugal defoaming, vacuum defoaming, ultrasonic defoaming, or the like, which are conventional in the art.
According to the invention, the solid content of the casting solution is 5-30wt%.
In the invention, the solid content of the casting film liquid meets the above range, and the control of the thickness of the polymer film is easier to realize in the preparation process.
Further, the solid content of the casting film liquid is 8-20wt%.
According to the invention, the polybenzimidazole has a number average molecular weight of 50000-300000.
In the invention, the number average molecular weight of the polybenzimidazole meets the range, the polymer has good solubility, and the prepared polymer has good mechanical properties.
Further, the number average molecular weight of the polybenzimidazole is 50000-200000.
According to the present invention, the porogen is selected from at least one of polyimide, polyethersulfone, polyetherimide, polysulfone, and polyethylene oxide.
According to the invention, the porogenic agent has a number average molecular weight of 3000-100000.
In the invention, the number average molecular weight of the pore-foaming agent meets the range, and the pore-foaming agent can be well mutually dissolved with polybenzimidazole, and can well etch a polymer film, so as to obtain a cross-transmission network pore structure.
Further, the number average molecular weight of the porogenic agent is 20000-100000.
According to the present invention, the first organic solvent is at least one selected from the group consisting of N, N-dimethylformamide, N-dimethylacetamide, dimethylsulfoxide and N-methylpyrrolidone.
In the present invention, the first organic solvent is selected from the above-mentioned types, and the gas separation membrane can have a cross-transport network pore structure.
According to the invention, the protonation treatment comprises: the polymer film is subjected to a first soaking in an acid solution.
In the present invention, it is preferable that the polymer film is dried and then subjected to the first soaking, and the drying manner and drying conditions are conventional in the art. For example, in the application, the drying condition is preferably that the drying is carried out for 2-3 hours at 60-70 ℃ in a blowing mode, and then the drying is carried out for 8-10 hours in a vacuum oven at 150-160 ℃, so that deformation in the drying process can be reduced, and the success rate of preparing the gas separation membrane can be improved.
In the invention, the protonation treatment can ensure that the PBI component structure is not damaged in the solvent etching process, and ensure the high selectivity of the gas separation membrane.
In the present invention, after the first soaking is completed, the washing, drying and other operations conventional in the art are further included, and the conditions may be conditions conventional in the art.
According to the invention, the acid solution is a monobasic acid solution.
Further, the acid solution is selected from at least one of methanesulfonic acid solution, hydrochloric acid solution, and acetic acid solution.
According to the invention, the concentration of the acid solution is 0.2 to 6mol/L, preferably 1 to 3mol/L.
According to the invention, the conditions of the first soaking include: soaking at 20-50deg.C for 1-7 days.
According to the invention, the porogen removal comprises: and carrying out second soaking on the protonated polymer film in a second organic solvent.
In the present invention, the protonated polymer film is preferably dried and then subjected to a second soak, wherein the drying means and drying conditions are conventional in the art.
In the invention, the operation of removing the pore-forming agent can enable the gas separation membrane to have a cross-transmission network-shaped pore structure, and the permeability coefficient is improved on the premise of ensuring the high selectivity of the gas separation membrane.
According to the present invention, the second organic solvent is at least one selected from the group consisting of N, N-dimethylformamide, N-dimethylacetamide, dimethylsulfoxide and N-methylpyrrolidone.
According to the present invention, the second soaking conditions include: the temperature is 20-80 ℃ and the time is 2-24h.
In the invention, the inventor researches and discovers that when the second soaking is carried out, the second organic solvent is replaced every 6-10 hours, so that the gas separation membrane with a more complete structure and a cross-transmission network-shaped pore structure can be obtained, and the gas permeability coefficient is further improved.
In the invention, after the second soaking is completed, the polymer film is soaked in the extractant for the third time.
In the present invention, the third soaking is to remove impurities such as the second organic solvent remaining in the polymer film.
According to the present invention, the extractant is selected from at least one of methanol, ethanol, isopropanol and deionized water.
In the present invention, the conditions for the third soaking are not particularly limited, and impurities such as the second organic solvent may be removed.
In the invention, after the third soaking is finished, the polymer film is subjected to conventional drying to obtain the gas separation membrane.
In one embodiment of the present invention, the gas separation membrane is prepared according to the following steps:
s1, adding polybenzimidazole (with the number average molecular weight of 50000-300000) and a pore-forming agent (with the number average molecular weight of 3000-100000) into a conical flask, adding a first organic solvent into the conical flask, stirring the mixture for 24-72h at the temperature of 40-80 ℃, cooling the mixture to room temperature, filtering the mixture, and performing vacuum defoaming to obtain casting film liquid with the solid content of 5-30wt%;
s2, uniformly coating the casting film liquid on the surface of the substrate, drying at 70-200 ℃ for 2-8 hours, cooling to room temperature, soaking in deionized water until the film naturally peels off from the surface of the substrate, and continuing to dry at 70-200 ℃ for 2-8 hours after the water on the surface of the film is absorbed, so as to obtain a polymer film;
s3, soaking the polymer film in 0.2-6mol/L acid solution at 20-50 ℃ for 1-7 days, taking out, washing, and drying at 70-200 ℃ for 2-8 hours to obtain a protonated polymer film;
s4, carrying out second soaking on the protonated polymer film in a second organic solvent for 2-24 hours at 20-80 ℃ to enable the second organic solvent to etch the protonated polymer film, dissolving a pore-forming agent component, carrying out third soaking on the etched film in an extractant, removing the second organic solvent remained in the film, and then carrying out ventilation drying at room temperature to obtain the gas separation film.
In a third aspect, the present invention provides a gas separation membrane prepared by the preparation method provided in the second aspect.
A fourth aspect of the present invention provides a gas separation membrane according to the first aspect of the present invention and the use of a gas separation membrane according to the third aspect of the present invention in gas separation.
The present invention will be described in detail by examples. In the following examples of the present invention,
the gas separation membrane is measured by an n-butanol liquid absorption method;
the microcosmic appearance of the gas separation membrane is measured by a Hitachi S-4800 type high-resolution field emission scanning electron microscope;
the permeability coefficient is measured by a gas permeation tester by adopting a differential pressure method;
the selectivity is obtained by dividing the permeability coefficients of different gases;
PBI membrane, available from Shanghai Cheng Jun technologies limited;
other chemicals were purchased from beijing enokic technologies limited.
The following examples and comparative examples are presented to illustrate the gas separation membranes produced
Example 1
S1, adding 1g of polybenzimidazole (with the number average molecular weight of 5.7 ten thousand and R1 being selected from formula c) and 1g of polyimide (with the number average molecular weight of 8.7 ten thousand) into a conical flask, wherein the mass ratio of the polybenzimidazole to a pore-forming agent is 1:1, then adding 18g of a first organic solvent N, N-dimethylacetamide, stirring for 24 hours at the temperature of 75 ℃, cooling to room temperature, filtering, and vacuum defoaming to obtain a casting film liquid with the solid content of 10 weight percent;
s2, uniformly coating the casting film liquid on the surface of a glass plate, drying for 4 hours at 75 ℃ under normal pressure, then drying for 8 hours in a vacuum oven at-0.1 MPa and 120 ℃, cooling to room temperature, soaking in deionized water until the film naturally peels off from the surface of the glass plate, and continuously drying for 8 hours in the vacuum oven at-0.1 MPa and 120 ℃ after the water on the surface of the film is absorbed by water absorption paper to obtain a polymer film;
s3, carrying out first soaking on the polymer film in 2mol/L methanesulfonic acid solution at 20 ℃ for 24 hours, taking out, repeatedly washing the surface of the film with deionized water, absorbing the moisture on the surface of the film with absorbent paper, and then drying in a vacuum oven at-0.1 MPa and 120 ℃ for 8 hours to obtain a protonated polymer film;
s4, carrying out second soaking on the protonated polymer film in a second organic solvent N, N-dimethylacetamide at 20 ℃ to enable the N, N-dimethylacetamide to etch the protonated polymer film, dissolving polyimide components of the mixed film, replacing the N, N-dimethylacetamide every 8 hours, carrying out third soaking on the etched film in ethanol, removing the second organic solvent remained in the film, and then carrying out ventilation drying at room temperature to obtain a gas separation film, and marking the gas separation film as S1.
Examples 2 to 4
In accordance with example 1, except that the second organic solvent N, N-dimethylacetamide in step S4 was replaced with N-methylpyrrolidone, dimethylsulfoxide and N, N-dimethylformamide, respectively, the same type of second organic solvent was replaced every 8 hours, to obtain a gas separation membrane, and labeled S2 to S4.
Example 5
In accordance with example 1, except that the number average molecular weight of polyimide was 2000, a gas separation membrane was obtained and labeled S5.
Example 6
In accordance with example 1, except that the amount of polybenzimidazole was 0.6g and the amount of polyimide was 1.4g, i.e., the mass ratio of polybenzimidazole to porogen was 3:7, the solid content of the casting solution was 10% by weight, a gas separation membrane was finally obtained and labeled S6.
Example 7
In accordance with example 1, except that the amount of polybenzimidazole was 0.8g and the amount of polyimide was 1.2g, i.e., the mass ratio of polybenzimidazole to porogen was 4:6, the solid content of the casting solution was 10wt%, a gas separation membrane was finally obtained and labeled S7.
Example 8
In accordance with example 1, except that the amount of polybenzimidazole was 2g, the amount of polyimide was 2g, and the mass of the first organic solvent N, N-dimethylacetamide was 96g, i.e., the mass ratio of polybenzimidazole to porogen was 1:1, the solid content of the casting solution was 4wt%, and a gas separation membrane was finally obtained and marked as S8.
Example 9
In accordance with example 1, except that the amount of polybenzimidazole was 1.6g and the amount of polyimide was 0.4g, i.e., the mass ratio of polybenzimidazole to porogen was 8:2, the solid content of the casting solution was 10wt%, a gas separation membrane was finally obtained, and labeled S9.
Example 10
S1, adding 1g of polybenzimidazole (with the number average molecular weight of 12.4 ten thousand and R1 being selected from the formula d) and 1g of polyethersulfone (with the number average molecular weight of 4.2 ten thousand) into a conical flask, wherein the mass ratio of the polybenzimidazole to a pore-forming agent is 1:1, then adding 23g of a first organic solvent N, N-dimethylacetamide, stirring for 24 hours at the temperature of 75 ℃, cooling to room temperature, filtering, and vacuum defoaming to obtain a casting film liquid with the solid content of 8 weight percent;
s2, simultaneously example 1;
s3, the same as that of the embodiment 1;
s4, the gas separation membrane is obtained in the same way as in example 1 and is marked as S1.
Example 11
In accordance with example 10, except that in step S3, the polymer film was subjected to a first soaking in a 2mol/L methanesulfonic acid solution at 20℃for 7 days, a gas separation membrane was obtained, and labeled S11.
Example 12
In accordance with example 10, except for step S4, the second soaking is: the protonated polybenzimidazole mixed membrane is subjected to a second soaking in a second organic solvent N, N-dimethylacetamide at 20 ℃ for 24 hours without replacement of the second organic solvent, so as to prepare a gas separation membrane, and the gas separation membrane is marked as S12.
Comparative example 1
Consistent with example 1, except that no porogen polyimide was added, a non-porous polybenzimidazole homogeneous membrane was obtained, labeled D1.
Comparative example 2
In accordance with example 1, except that the polymer film was immersed in a second organic solvent to dissolve polybenzimidazole without the protonation treatment, a film could not be prepared.
Comparative example 3
In accordance with example 1, except that no porogen removal treatment was performed, a hybrid film of non-porous polybenzimidazole and polyimide was obtained, labeled D3.
Comparative example 4
In the same manner as in example 1, except that the amount of polybenzimidazole was 0.4g and the amount of polyimide was 1.6g, i.e., the mass ratio of polybenzimidazole to porogen was 2:8, and the solid content of the casting solution was 20wt%, the entire film was dissolved when the protonated film was immersed in the second solvent, and a porous film could not be obtained.
Comparative example 5
Consistent with the procedure of example 1, except that the polybenzimidazole has a number average molecular weight of 5.7 ten thousand, R1 is selected from the following structural units:
it was found that it was not soluble in N, N-dimethylacetamide and subsequently unable to be formed into a film.
TABLE 1
| Sample of | Porosity/% |
| S1 | 46.07 |
| S2 | 45.71 |
| S3 | 45.22 |
| S4 | 44.37 |
| S5 | 46.38 |
| S6 | 55.7 |
| S7 | 66.75 |
| S9 | 17.6 |
| S10 | 47.65 |
| S11 | 45.72 |
| S12 | 37.6 |
| D1 | - |
| D3 | - |
In Table 1, it can be seen that the gas separation membranes prepared in examples 1 to 12 have a preferable porosity, and the preferable porosities in examples 1 to 4 and 9 to 11 are all within the preferable range. While the porosity of the gas separation membrane of example 5 is also in the preferred range, the gas separation membrane has a small number of interconnected network-like pores, and therefore is inferior in the subsequent application.
TABLE 2
As can be seen from Table 2, examples 1 to 12 of the present invention have a better technical effect, while 1 to 4, 9 to 11 satisfying the preferred embodiment have a significantly more excellent effect, such as a significant improvement in permeability coefficient for helium separation as compared with dense film D1, for He/N 2 The He selectivity of (c) is also slightly improved.
Wherein, fig. 1 is a surface topography diagram of the gas separation membrane prepared in example 4, fig. 2 is a longitudinal section diagram of the gas separation membrane prepared in example 4, and it can be seen from fig. 1 and 2 that the prepared pores are in a cross-transfer network shape and have uniform pore size distribution.
Further, it can be seen from a comparison of example 1 and examples 6 to 7 that when the ratio of polybenzimidazole to porogen is 1 (1 to 4), the He/N of the prepared porous film 2 、He/CH 4 、H 2 /N 2 、H 2 /CH 4 、CO 2 /N 2 、CO 2 /CH 4 High selectivity of He and H 2 、CO 2 Compared with a dense membrane, the permeability coefficient of the polybenzimidazole porous membrane is obviously improved, and the gas separation performance of the polybenzimidazole porous membrane can be effectively improved by a solution etching method.
The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, a number of simple variants of the technical solution of the invention are possible, including combinations of the individual technical features in any other suitable way, which simple variants and combinations should likewise be regarded as being disclosed by the invention, all falling within the scope of protection of the invention.
Claims (10)
1. A gas separation membrane, characterized in that the gas separation membrane has a cross-transfer network-like pore structure.
2. A gas separation membrane according to claim 1, having a porosity of 10-70%, preferably 17-50%.
3. A gas separation membrane according to claim 1 or 2, wherein the permeability coefficient of the gas separation membrane is 9-30Barrer, preferably 9-15Barrer.
4. A method of making a gas separation membrane, the method comprising:
s1, scraping and casting a film casting solution containing polybenzimidazole and a pore-forming agent on a substrate to form a film, and separating the film from the substrate to obtain a polymer film;
s2, carrying out protonation treatment on the polymer film to obtain a protonated polymer film;
s3, removing the pore-forming agent from the protonic polymer film to obtain the gas separation film;
wherein the mass ratio of the polybenzimidazole to the porogen is 3:7-9:1.
5. The method of claim 4, wherein the polybenzimidazole comprises a structural unit represented by formula (1):
wherein R1 is selected from structural units shown in formula a, formula b, formula c or formula d;
preferably, the mass ratio of the polybenzimidazole to the porogen is 1-9:1;
preferably, the method further comprises: mixing polybenzimidazole, a pore-forming agent and a first organic solvent, and defoaming to obtain a casting solution;
preferably, the solid content of the casting film liquid is 5 to 30wt%, preferably 8 to 20wt%.
6. The process according to claim 5, wherein the polybenzimidazole has a number average molecular weight of 50000-300000, preferably 50000-200000;
preferably, the porogen is selected from at least one of polyimide, polyethersulfone, polyetherimide, polysulfone, and polyethylene oxide;
preferably, the number average molecular weight of the porogen is 3000-100000, preferably 20000-100000;
preferably, the first organic solvent is selected from at least one of N, N-dimethylformamide, N-dimethylacetamide, dimethylsulfoxide and N-methylpyrrolidone.
7. The method of any of claims 4-6, wherein the protonating process comprises: carrying out first soaking on the polymer film in an acid solution;
preferably, the acid solution is a monobasic acid solution;
preferably, the acid solution is selected from at least one of methanesulfonic acid solution, hydrochloric acid solution, and acetic acid solution;
preferably, the concentration of the acid solution is 0.2-6mol/L, preferably 1-3mol/L;
preferably, the first soaking conditions include: soaking at 20-50deg.C for 1-7 days.
8. The method of any of claims 4-7, wherein the porogen removal comprises: carrying out second soaking on the protonated polymer film in a second organic solvent;
preferably, the second soaking conditions include: the temperature is 20-80 ℃ and the time is 2-24 hours;
preferably, the second organic solvent is selected from at least one of N, N-dimethylformamide, N-dimethylacetamide, dimethylsulfoxide and N-methylpyrrolidone.
9. A gas separation membrane prepared by the method of any one of claims 4-8.
10. Use of a gas separation membrane according to any one of claims 1-3 and a gas separation membrane according to claim 9 in gas separation.
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