CN104829853B - A kind of polyimide gas separating film and preparation method and application - Google Patents

Abstract

The invention discloses a polyimide gas separation membrane and its preparation method and application. The separation membrane is prepared by using a polyimide resin with a fluorine-containing benzene side group structure as shown in formula I. The polyimide gas separation membrane has the characteristics of high permeability and high selectivity, the permeability coefficient for CO ₂ is ≥180 barrer, and the selectivity coefficient for CO ₂ /CH ₄ exceeds 30, and the separation membrane shows excellent heat resistance properties and mechanical properties. This type of gas separation membrane has important application value in the separation and recovery of CO ₂ , including the separation of carbon dioxide and methane in biogas, the removal of acid gases such as carbon dioxide in natural gas, and the recovery of carbon dioxide in oilfield tertiary oil recovery.

Description

A kind of polyimide gas separation membrane and its preparation method and application

technical field

The invention relates to the field of membrane technology, in particular to a high-permeability and high-selectivity polyimide gas separation membrane and its preparation method and application.

Background technique

The use of membrane separation method to separate gas has been more and more widely used in industrial gas separation and purification in recent years due to its advantages of high separation efficiency, low energy loss, green environmental protection, simple operation, safety and reliability, and easy installation and debugging. . Membrane materials are the core of gas separation membrane technology. The current commercialized gas separation membrane materials are mainly cellulose (CA), polysulfone (PSF), polydimethylsiloxane (PDMS), polyphenylene oxide (PPO), etc. polymer film. However, the heat resistance of these gas separation membranes is not ideal, and the glass transition temperature does not exceed 200°C, so they are limited in some applications with special temperature requirements.

Due to its outstanding heat resistance, mechanical properties and good chemical stability, polyimide (PI) materials also have excellent gas selectivity. have attracted much attention in separation applications. However, due to the relatively strong intermolecular forces of polyimide, the arrangement of molecular chains is relatively dense, and the free volume fraction is relatively low, resulting in that although polyimide separation membranes have excellent gas selectivity, their gas permeability is not ideal. , the permeability coefficient of the commercialized polyimide separation membrane to _CO2 is only 10 barrer. The researchers improved the gas permeability of polyimide separation membranes by introducing bulky groups into the polyimide molecular structure to increase the free volume fraction. Ayala et al. by using dianhydrides 1,3-bis(3,4-dicarboxybenzoyl)5-tert-butylbenzene and 1,3-bis(3,4-dicarboxybenzoyl) containing bulky side groups Acyl)biphenyl and aromatic diamine 2,2-bis(4-aminophenyl)hexafluoropropane are polymerized to obtain polyimide, whose glass transition temperature is 265°C, and the polyimide separation membrane prepared by it has excellent Gas selectivity, the permeability coefficient of CO ₂ increased to 15.6 barrer (Ayala D, Lozano AE, de Abajo J, Garcia-Perez C, de la Campa JG, Peinemann KV, Freeman BD, Prabhakar R, Gas separation properties of aromatic polyimides . J Membr Sci, 2003, 215, 61-73). CN 101733027 A discloses a double-terminated amino polyether with long chain structure and 1,3-phenylenediamine and fluorine-containing aromatic dianhydride 4,4'-(2,2-hexafluoroisopropyl) di-ortho The polyimide separation membrane prepared by the copolymerization of phthalic anhydride (6FDA), because the introduction of the long-chain copolymerization structure breaks the original regular arrangement of the polymer molecular chain, so the permeability coefficient of the gas separation membrane to _CO2 is increased to 77.89 barrer, the highest selectivity coefficient for CO ₂ /CH ₄ is 20.03. In order to further improve the gas permeability of the polyimide separation membrane, Calle et al. adopted a bulky structure of 3,3,3", 4"-(5'-tert-butyl-m-trimethylbenzene)tetracarboxylic dianhydride and 2 , 4,6-trimethyl-m-phenylenediamine prepared polyimide separation membrane, the separation membrane showed excellent gas permeability, the permeability coefficient for _CO2 was as high as 465 barrer, but at the same time the gas selectivity decreased significantly, The selectivity coefficient for CO ₂ /CH ₄ is as low as 11.7 (Calle M, Garcia C, Lozano AE, de la Campa JG, de Abajo J, Alvarez C, Local chain mobility dependence on molecular structure in polyimides with bulky side groups: Correlation with gas separation properties, J Membr Sci, 2013, 434, 121-129).

Contents of the invention

The purpose of the present invention is to overcome the deficiencies in the prior art and provide a highly permeable and highly selective polyimide gas separation membrane prepared from a polyimide resin with a fluorine-containing benzene side group structure.

Another object of the present invention is to provide the preparation method and application of the above-mentioned resin and gas separation membrane.

To achieve the above object, the present invention provides the following technical solutions:

A polyimide gas separation membrane, wherein the separation membrane is made from a polyimide resin with a fluorine-containing benzene side group structure, and the polyimide resin has a general structural formula shown in the following formula I:

Wherein, Ar is selected from any one of the following groups:

X is _CH3 or F,

Y is H or CH ₃ ,

L, M, and N are the same or different, and are independently selected from H, F, or CF ₃ , and at least one of L, M, and N is F or CF ₃ ,

n is an integer of 50-300.

According to the present invention, the number average molecular weight (M _n ) of the polyimide resin is between 50000-200000 g/mol.

According to the present invention, the thickness of the separation membrane is 25-75 μm. The gas separation membrane has both high gas permeability and high gas selectivity. Specifically, the permeability coefficient PCO ₂ to CO ₂ is ≥180 barrer, and the highest can reach 280 barrer; the selectivity coefficient to CO ₂ /CH ₄ exceeds 30, the highest Up to 40. At the same time, the gas separation membrane exhibits excellent heat resistance (the glass transition temperature T _g is between 340-380° C.) and mechanical properties (the tensile strength T _s is between 90-120 MPa).

The present invention also provides a preparation method of the polyimide resin in the above-mentioned gas separation membrane, which is characterized in that the method comprises the following steps: under the protection of an inert gas, the aromatic Diamine is dissolved in organic solvent, then adds aromatic dianhydride shown in formula III, obtains polyimide resin of the present invention,

in,

The definition of X, Y, L, M, N and Ar is the same as formula I.

Preferably, stir formula II and formula III until they are completely dissolved to obtain a homogeneous solution, then add a catalyst and a dehydrating agent to raise the temperature for reaction, remove the dehydrating agent after the reaction is completed, pour the precipitant into the polyimide resin after cooling :

In the above method, the aromatic dianhydride represented by formula III is specifically 4,4'-(hexafluoroisopropyl)diphthalic anhydride (6FDA), 4,4'-(2,2,2-trifluoroform Base-1-phenyl-ethylene) diphthalic anhydride (3FDA), 4,4'-[2,2,2-trifluoromethyl-1-(3-trifluoromethylphenyl)-ethylene ]diphthalic anhydride (HFDA), 4,4'-[2,2,2-trifluoromethyl-1-(3,5-bistrifluoromethylphenyl)-ethylene]diphthalic anhydride (9FDA), Triptyl-2,3,6,7-tetradecyl dianhydride (TDA), 1,4-bis(3',4'-dicarboxyphenoxy) triptyl dianhydride (TODA), 9,9 - Bis(3,4-dianhydride-phenoxyphenyl)fluorene (BAOFL).

In the above method, the aromatic diamine represented by formula II having a fluorine-containing benzene side group structure is specifically α,α-bis(4-amino-3,5-dimethylphenyl)-1-(4'-trifluoro Methylphenyl)methane, α,α-bis(4-amino-3,5-dimethylphenyl)-1-(3',5'-bistrifluoromethylphenyl)methane, α,α -Bis(4-amino-3,5-dimethylphenyl)-1-(4'-fluorophenyl)methane, α,α-bis(4-amino-3,5-dimethylphenyl) -1-(3',5'-difluorophenyl)methane, α,α-bis(4-amino-3,5-dimethylphenyl)-1-(3',4',5'- Trifluorophenyl)methane, α,α-bis(4-amino-3,5-dimethylphenyl)-1-(4'-trifluoromethylphenyl)ethane, α,α-bis( 4-amino-3,5-dimethylphenyl)-1-(3',5'-bistrifluoromethylphenyl)ethane, α,α-bis(4-amino-3,5-di Methylphenyl)-1-(4'-fluorophenyl)ethane, α,α-bis(4-amino-3,5-dimethylphenyl)-1-(3',5'-di Fluorophenyl)ethane, α,α-bis(4-amino-3,5-dimethylphenyl)-1-(3',4',5'-trifluorophenyl)ethane, α, α-bis(4-amino-3,5-difluorophenyl)-1-(4'-trifluoromethylphenyl)methane, α,α-bis(4-amino-3,5-difluorobenzene base)-1-(4'-fluorophenyl)methane, α,α-bis(4-amino-3,5-difluorophenyl)-1-(4'-trifluoromethylphenyl)ethane , α,α-bis(4-amino-3,5-difluorophenyl)-1-(4'-fluorophenyl)ethane.

The organic solvent is selected from N-methylpyrrolidone (NMP), γ-butyrolactone, dimethylsulfoxide (DMSO), N,N-dimethylacetamide (DMAc) and N,N-dimethyl At least one of formamide (DMF).

The catalyst is selected from one of isoquinoline, quinoline, triethylamine or pyridine.

The dehydrating agent is toluene or xylene.

The precipitating agent is at least one selected from water, methanol, ethanol, propanol, butanol or isopropanol.

The molar ratio of the aromatic diamine having a fluorine-containing benzene side group structure to the aromatic dianhydride is 0.95-1.05:1.0.

The solid content of the homogeneous solution is 25-40 wt.%.

The molar ratio of the catalyst to the aromatic dianhydride is 0.05-0.1:1.0.

The temperature for the reaction by raising the temperature is 140-180° C.; the time is 8-12 hours.

The present invention also provides the preparation method of above-mentioned polyimide gas separation membrane, comprises the steps:

Dissolving the above-mentioned polyimide resin with fluorine-containing benzene side group structure in an organic solvent to obtain the resin solution, and then coating the resin solution on the substrate, after drying, immersing in deionized water to peel off, The polyimide gas separation membrane was obtained.

In the above gas separation membrane preparation method, the organic solvent is selected from N-methylpyrrolidone (NMP), γ-butyrolactone, dimethylsulfoxide (DMSO), N,N-dimethylacetamide (DMAc) and at least one of N,N-dimethylformamide (DMF).

The base material is a glass plate or a stainless steel plate.

The solid content of the resin solution is 25-45wt.%.

In the drying step, the temperature is 80-200° C., and the time is 3-5 hours.

The present invention also provides the application of the above-mentioned polyimide gas separation membrane, which is used for the separation and recovery of carbon dioxide.

The separation and recovery include the separation of carbon dioxide and methane in biogas, the removal of acid gases such as carbon dioxide in natural gas, or the recovery of carbon dioxide in oilfield tertiary oil recovery, etc.

The beneficial effects of the present invention are:

The polyimide gas separation membrane provided by the invention has both high permeability and high selectivity, and also has excellent heat resistance and mechanical properties, and is more suitable for the separation and recovery of carbon dioxide. Specifically, the present invention uses aromatic dianhydrides with bulky structures and aromatic diamines with fluorine-containing benzene side group structures to prepare polyimides. The combination of dianhydrides with bulky structures and diamines with large side groups can effectively inhibit the close packing of molecular chains, increase the distance between molecular chains, and increase the free volume fraction of polymers, thereby providing more micropores that are conducive to gas transmission. In order to improve the gas permeability of the separation membrane; at the same time, by introducing fluorine-containing groups into the polymer structure, the interaction between fluorine atoms and carbon dioxide molecules is used to accelerate the dissolution process of carbon dioxide gas, thereby further improving the separation membrane. The permeability of carbon dioxide; in addition, the rigid polymer backbone structure can not only obtain polyimide with excellent heat resistance, but also help to maintain the high gas selectivity of polyimide separation membrane.

Description of drawings

Fig. 1 is the infrared spectrogram of the polyimide separation membrane that embodiment 1 prepares.

detailed description

The present invention will be further described below in conjunction with specific examples, but the present invention is not limited to the following examples. The methods are conventional methods unless otherwise specified. The raw materials can be obtained from public commercial channels unless otherwise specified. In the present invention, percentage content and percentage concentration are mass percentage content and mass percentage concentration unless otherwise specified.

Embodiment 1, the preparation of polyimide gas separation membrane

In a three-necked flask equipped with a mechanical stirrer, a water separator, a nitrogen inlet and outlet, and a thermometer, add 39.85 grams (0.1 mol) of α,α-bis(4-amino-3,5-dimethylphenyl)-1-( 4'-trifluoromethylphenyl) methane and N-methylpyrrolidone (NMP) 126 grams, stirred under nitrogen protection until completely dissolved, then added 44.42 grams (0.1 mole) 4,4'-(hexafluoroisopropyl Base) two phthalic anhydride (6FDA), to obtain a solid content of 40wt.% of the homogeneous solution. 0.65 g (0.005 mole) of isoquinoline and 21 g of toluene were added to the above homogeneous solution, the temperature of the reaction system was raised to 180° C. and reacted for 12 hours, the toluene was distilled off, and the heating was stopped. Cool the reaction solution to 80-120°C and pour it into methanol to obtain a fibrous crude product, collect the precipitated crude product, wash repeatedly with methanol and water, filter, pulverize, and dry to obtain a polyimide resin with a yield of 97%, and the number average molecular weight (M _n ) is 1.69×10 ⁵ g/mol.

The above-mentioned polyimide resin is dissolved in N-methylpyrrolidone (NMP) to obtain a resin solution with a solid content of 40wt.%. After filtering and vacuum defoaming, it is coated on a glass plate or a stainless steel plate with a smooth surface. After 80°C/1 hour, 120°C/1 hour, 160°C/1 hour, 180°C/1 hour, 200°C/1 hour step-up heating in air atmosphere, immerse the glass plate or stainless steel plate in deionized water The separation membrane is peeled off automatically, and a polyimide separation membrane with a certain thickness is obtained by vacuum drying at 120°C.

FT-IR (film, cm ⁻¹ ): 2925, 1787, 1733, 1622, 1527, 1487, 1440, 1369, 1298, 1257, 1209, 1145, 1110, 1045, 723.

The thickness of the separation film can be controlled by adjusting the model of the coating roller. The main properties of the polyimide separation membrane are shown in Table 1.

Embodiment 2, the preparation of polyimide gas separation membrane

In a three-necked flask equipped with a mechanical stirrer, a water separator, a nitrogen inlet and outlet, and a thermometer, add 34.85 grams (0.1 moles) of α,α-bis(4-amino-3,5-dimethylphenyl)-1-( 4'-fluorophenyl)methane and N,N-dimethylacetamide (DMAc) 147 grams, stirred under nitrogen protection until completely dissolved, then added 44.42 grams (0.1 mole) 4,4'-(hexafluoroiso Propyl) diphthalic anhydride (6FDA) to obtain a homogeneous solution with a solid content of 35wt.%. 1.29 grams (0.01 moles) of quinoline and 25 grams of xylene were added to the above homogeneous solution, the temperature of the reaction system was raised to 140° C. for 12 hours, the xylene was distilled off, and the heating was stopped. Cool the reaction solution to 80-120°C and pour it into ethanol to obtain a fibrous crude product, collect the precipitated crude product, wash repeatedly with ethanol and water, filter, pulverize, and dry to obtain a polyimide resin with a yield of 98%, and the number average molecular weight (M _n ) is 1.99×10 ⁵ g/mol.

The above-mentioned polyimide resin is dissolved in N-methylpyrrolidone (NMP) to obtain a resin solution with a solid content of 40wt.%. After filtering and vacuum defoaming, it is coated on a glass plate or a stainless steel plate with a smooth surface. After 80°C/1 hour, 120°C/1 hour, 160°C/1 hour, 180°C/1 hour, 200°C/1 hour step-up heating in air atmosphere, immerse the glass plate or stainless steel plate in deionized water The separation membrane is peeled off automatically, and a polyimide separation membrane with a certain thickness is obtained by vacuum drying at 120°C. The thickness of the separation film can be controlled by adjusting the model of the coating roller. The main properties of the polyimide separation membrane are shown in Table 1.

Embodiment 3, the preparation of polyimide gas separation membrane

In a three-necked flask equipped with a mechanical stirrer, a water separator, a nitrogen inlet and outlet, and a thermometer, add 38.44 grams (0.1 mol) of α,α-bis(4-amino-3,5-dimethylphenyl)-1-( 3',4',5'-trifluorophenyl) methane and N-methylpyrrolidone (NMP) 154 grams, stirred under nitrogen protection until completely dissolved, then added 44.42 grams (0.1 mol) 4,4'-( Hexafluoroisopropyl) diphthalic anhydride (6FDA) to obtain a homogeneous solution with a solid content of 35wt.%. 1.29 grams (0.01 moles) of quinoline and 26 grams of toluene were added to the above-mentioned homogeneous solution, the temperature of the reaction system was raised to 180° C. and reacted for 10 hours, the toluene was distilled off, and the heating was stopped. Cool the reaction solution to 80-120°C and pour it into ethanol to obtain a fibrous crude product, collect the precipitated crude product, wash repeatedly with ethanol and water, filter, pulverize, and dry to obtain a polyimide resin with a yield of 99%, and the number average molecular weight (M _n ) is 1.86×10 ⁵ g/mol.

The above-mentioned polyimide resin is dissolved in N-methylpyrrolidone (NMP) to obtain a resin solution with a solid content of 40wt.%. After filtering and vacuum defoaming, it is coated on a glass plate or a stainless steel plate with a smooth surface. After 80°C/1 hour, 120°C/1 hour, 160°C/1 hour, 180°C/1 hour, 200°C/1 hour step-up heating in air atmosphere, immerse the glass plate or stainless steel plate in deionized water The separation membrane is peeled off automatically, and a polyimide separation membrane with a certain thickness is obtained by vacuum drying at 120°C. The thickness of the separation film can be controlled by adjusting the model of the coating roller. The main properties of the polyimide separation membrane are shown in Table 1.

Embodiment 4, the preparation of polyimide gas separation membrane

In a three-necked flask equipped with a mechanical stirrer, a water separator, a nitrogen inlet and outlet, and a thermometer, add 48.05 grams (0.1 mol) of α,α-bis(4-amino-3,5-dimethylphenyl)-1-( 3',5'-bistrifluoromethylphenyl)ethane and 218 grams of γ-butyrolactone, stirred under nitrogen protection until completely dissolved, then added 45.23 grams (0.1 mol) of 4,4'-(2, 2,2-trifluoromethyl-1-phenyl-ethylene) diphthalic anhydride (3FDA) to obtain a homogeneous solution with a solid content of 30 wt.%. 1.03 grams (0.008 moles) of isoquinoline and 36 grams of toluene were added to the above-mentioned homogeneous solution, and the temperature of the reaction system was raised to 180° C. and reacted for 8 hours, the toluene was distilled off, and the heating was stopped. Cool the reaction solution to 80-120°C and pour it into the ethanol/water mixture (ethanol/water volume ratio = 3:1) to obtain a fibrous crude product. Collect the precipitated crude product, wash it repeatedly with ethanol and water, and then filter. Pulverized and dried to obtain a polyimide resin with a yield of 96% and a number average molecular weight (M _n ) of 1.47×10 ⁵ g/mol.

The above-mentioned polyimide resin is dissolved in γ-butyrolactone to obtain a resin solution with a solid content of 30wt.%. After filtering and vacuum defoaming, it is coated on a glass plate or a stainless steel plate with a smooth surface. After heating at 80°C/1 hour, 120°C/1 hour, 160°C/1 hour, 180°C/1 hour, and 200°C/1 hour, the glass plate or stainless steel plate is immersed in deionized water to make the separation membrane Automatic peeling, vacuum drying at 120°C to obtain a polyimide separation membrane with a certain thickness. The thickness of the separation film can be controlled by adjusting the model of the coating roller. The main properties of the polyimide separation membrane are shown in Table 1.

Embodiment 5, the preparation of polyimide gas separation membrane

In a three-necked flask equipped with a mechanical stirrer, a water separator, a nitrogen inlet and outlet, and a thermometer, add 38.25 grams (0.105 moles) of α,α-bis(4-amino-3,5-difluorophenyl)-1-(4 '-fluorophenyl)methane and N,N-dimethylacetamide (DMAc) 195 grams, stirred under nitrogen protection until completely dissolved, then added 45.23 grams (0.1 mole) 4,4'-(2,2, 2-trifluoromethyl-1-phenyl-ethylene) diphthalic anhydride (3FDA) to obtain a homogeneous solution with a solid content of 30 wt.%. 1.01 g (0.01 mole) of triethylamine and 32 g of xylene were added to the above-mentioned homogeneous solution, and the temperature of the reaction system was raised to 140° C. to react for 12 hours, then the xylene was distilled off, and the heating was stopped. Cool the reaction solution to 80-120°C and pour it into propanol to obtain a fibrous crude product. Collect the precipitated crude product, wash it repeatedly with propanol and water, filter, pulverize, and dry to obtain a polyimide resin. The yield is is 97%, and the number average molecular weight (M _n ) is 6.4×10 ⁴ g/mol.

The above polyimide resin was dissolved in N,N-dimethylacetamide (DMAc) to obtain a resin solution with a solid content of 35wt.%. After filtering and vacuum defoaming, it was coated on a smooth glass plate or After the stainless steel plate is heated in an air atmosphere at 80°C/1 hour, 120°C/1 hour, 160°C/1 hour, and 180°C/1 hour, the glass plate or stainless steel plate is immersed in deionized water to separate The membrane is automatically peeled off, and a polyimide separation membrane with a certain thickness is obtained by vacuum drying at 120°C. The thickness of the separation film can be controlled by adjusting the model of the coating roller. The main properties of the polyimide separation membrane are shown in Table 1.

Embodiment 6, the preparation of polyimide gas separation membrane

In a three-necked flask equipped with a mechanical stirrer, a water separator, a nitrogen inlet and outlet, and a thermometer, add 36.64 grams (0.1 mol) of α,α-bis(4-amino-3,5-dimethylphenyl)-1-( 3',5'-difluorophenyl)methane and N,N-dimethylformamide (DMF) 133 grams, stirred under nitrogen protection until completely dissolved, then added 52.03 grams (0.1 moles) of 4,4'- [2,2,2-Trifluoromethyl-1-(3-trifluoromethylphenyl)-ethylene]diphthalic anhydride (HFDA) to obtain a homogeneous solution with a solid content of 40wt.%. 0.63 g (0.008 mol) of triethylamine and 22 g of xylene were added to the above homogeneous solution, and the temperature of the reaction system was raised to 140° C. to react for 10 hours, then the xylene was distilled off and the heating was stopped. Cool the reaction solution to 80-120°C and pour it into methanol to obtain a fibrous crude product, collect the precipitated crude product, wash repeatedly with methanol and water, filter, pulverize, and dry to obtain a polyimide resin with a yield of 98%, and the number average molecular weight (M _n ) is 1.74×10 ⁵ g/mol.

The above polyimide resin was dissolved in N,N-dimethylacetamide (DMAc) to obtain a resin solution with a solid content of 45wt.%. After filtering and vacuum defoaming, it was coated on a smooth glass plate or After the stainless steel plate is heated in an air atmosphere at 80°C/1 hour, 120°C/1 hour, 160°C/1 hour, and 180°C/1 hour, the glass plate or stainless steel plate is immersed in deionized water to separate The membrane is automatically peeled off, and a polyimide separation membrane with a certain thickness is obtained by vacuum drying at 120°C. The thickness of the separation film can be controlled by adjusting the model of the coating roller. The main properties of the polyimide separation membrane are shown in Table 1.

Embodiment 7, the preparation of polyimide gas separation membrane

In a three-necked flask equipped with a mechanical stirrer, a water separator, a nitrogen inlet and outlet, and a thermometer, add 41.25 grams (0.1 moles) of α,α-bis(4-amino-3,5-dimethylphenyl)-1-( 4'-trifluoromethylphenyl) ethane and N-methylpyrrolidone (NMP) 173 grams, stirred under nitrogen protection until completely dissolved, then added 52.03 grams (0.1 mole) 4,4'-[2,2 , 2-trifluoromethyl-1-(3-trifluoromethylphenyl)-ethylene]diphthalic anhydride (HFDA) to obtain a homogeneous solution with a solid content of 35wt.%. 0.65 g (0.005 mole) of isoquinoline and 29 g of toluene were added to the above homogeneous solution, the temperature of the reaction system was raised to 180° C. and reacted for 8 hours, the toluene was distilled off, and the heating was stopped. Cool the reaction solution to 80-120°C and pour it into a methanol/water mixture (methanol/water volume ratio = 1:1) to obtain a fibrous crude product. Collect the precipitated crude product, wash it repeatedly with methanol and water, and then filter. Pulverized and dried to obtain a polyimide resin with a yield of 97% and a number average molecular weight (M _n ) of 1.27×10 ⁵ g/mol.

The above-mentioned polyimide resin is dissolved in γ-butyrolactone to obtain a resin solution with a solid content of 35wt.%. After filtering and vacuum defoaming, it is coated on a glass plate or a stainless steel plate with a smooth surface. After heating at 80°C/1 hour, 120°C/1 hour, 160°C/1 hour, 180°C/1 hour, and 200°C/1 hour, the glass plate or stainless steel plate is immersed in deionized water to make the separation membrane Automatic peeling, vacuum drying at 120°C to obtain a polyimide separation membrane with a certain thickness. The thickness of the separation film can be controlled by adjusting the model of the coating roller. The main properties of the polyimide separation membrane are shown in Table 1.

Embodiment 8, the preparation of polyimide gas separation membrane

In a three-necked flask equipped with a mechanical stirrer, a water separator, a nitrogen inlet and outlet, and a thermometer, add 43.50 grams (0.105 moles) of α,α-bis(4-amino-3,5-difluorophenyl)-1-(4 '-Trifluoromethylphenyl) methane and dimethyl sulfoxide (DMSO) 287 grams, stirred under nitrogen protection until completely dissolved, then added 52.03 grams (0.1 moles) of 4,4'-[2,2,2 - Trifluoromethyl-1-(3-trifluoromethylphenyl)-ethylene]diphthalic anhydride (HFDA), to obtain a homogeneous solution with a solid content of 25 wt.%. 0.79 g (0.01 mole) of pyridine and 48 g of toluene were added to the above homogeneous solution, the temperature of the reaction system was raised to 160° C. and reacted for 12 hours, the toluene was distilled off, and the heating was stopped. Cool the reaction solution to 80-120°C and pour it into propanol to obtain a fibrous crude product. Collect the precipitated crude product, wash it repeatedly with propanol and water, filter, pulverize, and dry to obtain a polyimide resin. The yield is is 96%, and the number average molecular weight (M _n ) is 7.03×10 ⁴ g/mol.

The above-mentioned polyimide resin is dissolved in dimethyl sulfoxide (DMSO) to obtain a resin solution with a solid content of 30wt.%. After filtering and vacuum defoaming, it is coated on a glass plate or a stainless steel plate with a smooth surface. After 80°C/1 hour, 120°C/1 hour, 160°C/1 hour, 180°C/1 hour, 200°C/1 hour step-up heating in air atmosphere, immerse the glass plate or stainless steel plate in deionized water The separation membrane is peeled off automatically, and a polyimide separation membrane with a certain thickness is obtained by vacuum drying at 120°C. The thickness of the separation film can be controlled by adjusting the model of the coating roller. The main properties of the polyimide separation membrane are shown in Table 1.

Embodiment 9, the preparation of polyimide gas separation membrane

In a three-necked flask equipped with a mechanical stirrer, a water separator, a nitrogen inlet and outlet, and a thermometer, add 36.25 grams (0.1 moles) of α,α-bis(4-amino-3,5-dimethylphenyl)-1-( 4'-fluorophenyl) ethane and N-methylpyrrolidone (NMP) 177 grams, stirred under nitrogen protection until completely dissolved, then added 58.83 grams (0.1 mole) 4,4'-[2,2,2- Trifluoromethyl-1-(3,5-bistrifluoromethylphenyl)-ethylene]diphthalic anhydride (9FDA) to obtain a homogeneous solution with a solid content of 35 wt.%. 1.29 g (0.01 mole) of quinoline and 29 g of toluene were added to the above homogeneous solution, the temperature of the reaction system was raised to 180° C. and reacted for 10 hours, the toluene was distilled off, and the heating was stopped. Cool the reaction solution to 80-120°C and pour it into a methanol/water mixture (methanol/water volume ratio = 3:1) to obtain a fibrous crude product. Collect the precipitated crude product, wash it repeatedly with methanol and water, and then filter. Pulverized and dried to obtain a polyimide resin with a yield of 97% and a number average molecular weight (M _n ) of 1.51×10 ⁵ g/mol.

The above polyimide resin was dissolved in N,N-dimethylacetamide (DMAc) to obtain a resin solution with a solid content of 35wt.%. After filtering and vacuum defoaming, it was coated on a smooth glass plate or After the stainless steel plate is heated in an air atmosphere at 80°C/1 hour, 120°C/1 hour, 160°C/1 hour, and 180°C/1 hour, the glass plate or stainless steel plate is immersed in deionized water to separate The membrane is automatically peeled off, and a polyimide separation membrane with a certain thickness is obtained by vacuum drying at 120°C. The thickness of the separation film can be controlled by adjusting the model of the coating roller. The main properties of the polyimide separation membrane are shown in Table 1.

Embodiment 10, the preparation of polyimide gas separation membrane

In a three-necked flask equipped with a mechanical stirrer, a water separator, a nitrogen inlet and outlet, and a thermometer, add 39.85 grams (0.1 mol) of α,α-bis(4-amino-3,5-dimethylphenyl)-1-( 3',4',5'-trifluorophenyl)ethane and N,N-dimethylformamide (DMF) 148 grams, stirred under nitrogen protection until completely dissolved, then added 58.83 grams (0.1 moles) of 4 , 4'-[2,2,2-trifluoromethyl-1-(3,5-bistrifluoromethylphenyl)-ethylene]diphthalic anhydride (9FDA), to obtain a solid content of 40wt.% homogeneous solution. 0.40 g (0.005 mol) of pyridine and 25 g of xylene were added to the above homogeneous solution, and the temperature of the reaction system was raised to 140° C. to react for 12 hours, then the xylene was distilled off and the heating was stopped. Cool the reaction solution to 80-120°C and pour it into isopropanol to obtain a fibrous crude product. Collect the precipitated crude product, wash it repeatedly with isopropanol and water, filter, pulverize, and dry to obtain a polyimide resin. The yield was 97%, and the number average molecular weight (M _n ) was 1.36×10 ⁵ g/mol.

The above-mentioned polyimide resin is dissolved in dimethyl sulfoxide (DMSO) to obtain a resin solution with a solid content of 35wt.%. After filtering and vacuum defoaming, it is coated on a glass plate or a stainless steel plate with a smooth surface. After 80°C/1 hour, 120°C/1 hour, 160°C/1 hour, 180°C/1 hour, 200°C/1 hour step-up heating in air atmosphere, immerse the glass plate or stainless steel plate in deionized water The separation membrane is peeled off automatically, and a polyimide separation membrane with a certain thickness is obtained by vacuum drying at 120°C. The thickness of the separation film can be controlled by adjusting the model of the coating roller. The main properties of the polyimide separation membrane are shown in Table 1.

Embodiment 11, the preparation of polyimide gas separation membrane

In a three-necked flask equipped with a mechanical stirrer, a water separator, a nitrogen inlet and outlet, and a thermometer, add 39.72 grams (0.105 moles) of α,α-bis(4-amino-3,5-difluorophenyl)-1-(4 '-Fluorophenyl) ethane and N,N-dimethylformamide (DMF) 230 grams, stirred under nitrogen protection until completely dissolved, then added 58.83 grams (0.1 mole) 4,4'-[2,2 , 2-trifluoromethyl-1-(3,5-bistrifluoromethylphenyl)-ethylene]diphthalic anhydride (9FDA) to obtain a homogeneous solution with a solid content of 30wt.%. 0.79 g (0.01 mole) of pyridine and 38 g of xylene were added to the above homogeneous solution, and the temperature of the reaction system was raised to 140° C. to react for 12 hours, then the xylene was distilled off and the heating was stopped. Cool the reaction solution to 80-120°C and pour it into isopropanol to obtain a fibrous crude product. Collect the precipitated crude product, wash it repeatedly with isopropanol and water, filter, pulverize, and dry to obtain a polyimide resin. The yield was 96%, and the number average molecular weight (M _n ) was 5.01×10 ⁴ g/mol.

Dissolve the above polyimide resin in N,N-dimethylformamide (DMF) to obtain a resin solution with a solid content of 25wt.%. After filtering and vacuum defoaming, apply it to a smooth glass plate or After the stainless steel plate is heated in an air atmosphere at 80°C/1 hour, 120°C/1 hour, and 160°C/1 hour, the glass plate or stainless steel plate is immersed in deionized water to automatically peel off the separation membrane. After 120 °C and vacuum-dried to obtain a polyimide separation membrane with a certain thickness. The thickness of the separation film can be controlled by adjusting the model of the coating roller. The main properties of the polyimide separation membrane are shown in Table 1.

Embodiment 12, the preparation of polyimide gas separation membrane

In a three-necked flask equipped with a mechanical stirrer, a water separator, a nitrogen inlet and outlet, and a thermometer, add 44.31 grams (0.095 moles) of α,α-bis(4-amino-3,5-dimethylphenyl)-1-( 3',5'-bistrifluoromethylphenyl)methane and 195 grams of γ-butyrolactone, stirred under nitrogen protection until completely dissolved, then added 39.43 grams (0.1 moles) of triptycene-2,3,6 , 7-tetraacid dianhydride (TDA) to obtain a homogeneous solution with a solid content of 30wt.%. 0.65 g (0.005 mole) of isoquinoline and 32 g of xylene were added to the above-mentioned homogeneous solution, and the temperature of the reaction system was raised to 180° C. and reacted for 12 hours, then the xylene was distilled off, and the heating was stopped. Cool the reaction solution to 80-120°C and pour it into butanol to obtain a fibrous crude product. Collect the precipitated crude product, wash it repeatedly with butanol and water, filter, pulverize, and dry to obtain a polyimide resin. The yield is is 97%, and the number average molecular weight (M _n ) is 8.15×10 ⁴ g/mol.

The above-mentioned polyimide resin is dissolved in γ-butyrolactone to obtain a resin solution with a solid content of 30wt.%. After filtering and vacuum defoaming, it is coated on a glass plate or a stainless steel plate with a smooth surface. After heating at 80°C/1 hour, 120°C/1 hour, 160°C/1 hour, 180°C/1 hour, and 200°C/1 hour, the glass plate or stainless steel plate is immersed in deionized water to make the separation membrane Automatic peeling, vacuum drying at 120°C to obtain a polyimide separation membrane with a certain thickness. The thickness of the separation film can be controlled by adjusting the model of the coating roller. The main properties of the polyimide separation membrane are shown in Table 1.

Embodiment 13, the preparation of polyimide gas separation membrane

In a three-necked flask equipped with a mechanical stirrer, a water separator, a nitrogen inlet and outlet, and a thermometer, add 38.05 grams (0.1 moles) of α,α-bis(4-amino-3,5-dimethylphenyl)-1-( 3',5'-Difluorophenyl)ethane and 178 grams of dimethyl sulfoxide (DMSO), stirred under nitrogen protection until completely dissolved, then added 57.85 grams (0.1 moles) of 1,4-bis(3' , 4'-dicarboxyphenoxy) triptycene dianhydride (TODA), to obtain a homogeneous solution with a solid content of 35wt.%. 0.50 g (0.005 mol) of triethylamine and 30 g of xylene were added to the above homogeneous solution, the temperature of the reaction system was raised to 160° C. and reacted for 12 hours, the xylene was distilled off, and the heating was stopped. Cool the reaction solution to 80-120°C and pour it into ethanol to obtain a fibrous crude product, collect the precipitated crude product, wash repeatedly with ethanol and water, filter, pulverize, and dry to obtain a polyimide resin with a yield of 97%, and the number average molecular weight (M _n ) is 9.24×10 ⁴ g/mol.

Dissolve the above polyimide resin in N,N-dimethylacetamide (DMAc) to obtain a resin solution with a solid content of 40wt.%. After filtering and vacuum defoaming, apply it to a smooth glass plate or After the stainless steel plate is heated in an air atmosphere at 80°C/1 hour, 120°C/1 hour, 160°C/1 hour, and 180°C/1 hour, the glass plate or stainless steel plate is immersed in deionized water to separate The membrane is automatically peeled off, and a polyimide separation membrane with a certain thickness is obtained by vacuum drying at 120°C. The thickness of the separation film can be controlled by adjusting the model of the coating roller. The main properties of the polyimide separation membrane are shown in Table 1.

Embodiment 14, the preparation of polyimide gas separation membrane

In a three-necked flask equipped with a mechanical stirrer, a water separator, a nitrogen inlet and outlet, and a thermometer, add 44.98 grams (0.105 moles) of α,α-bis(4-amino-3,5-difluorophenyl)-1-(4 '-Trifluoromethylphenyl) ethane and N-methylpyrrolidone (NMP) 203 grams, stirred under nitrogen protection until completely dissolved, then added 64.26 grams (0.1 moles) of 9,9-bis(3,4- Dianhydride-based phenoxyphenyl) fluorene (BAOFL) to obtain a homogeneous solution with a solid content of 35 wt.%. 0.65 g (0.005 mol) of quinoline and 34 g of toluene were added to the above homogeneous solution, the temperature of the reaction system was raised to 180° C. and reacted for 10 hours, the toluene was distilled off, and the heating was stopped. Cool the reaction solution to 80-120°C and pour it into the ethanol/water mixture (ethanol/water volume ratio = 1:1) to obtain a fibrous crude product. Collect the precipitated crude product, wash it repeatedly with ethanol and water, and then filter it. Pulverized and dried to obtain a polyimide resin with a yield of 96% and a number average molecular weight (M _n ) of 5.93×10 ⁴ g/mol.

Dissolve the above polyimide resin in N,N-dimethylacetamide (DMAc) to obtain a resin solution with a solid content of 30wt.%. After filtering and vacuum defoaming, apply it to a smooth glass plate or After the stainless steel plate is heated in an air atmosphere at 80°C/1 hour, 120°C/1 hour, 160°C/1 hour, and 180°C/1 hour, the glass plate or stainless steel plate is immersed in deionized water to separate The membrane is automatically peeled off, and a polyimide separation membrane with a certain thickness is obtained by vacuum drying at 120°C. The thickness of the separation film can be controlled by adjusting the model of the coating roller. The main properties of the polyimide separation membrane are shown in Table 1.

Table 1. Main properties of polyimide gas separation membrane

^aHeat resistance is determined by dynamic mechanical analysis, where T _g is the glass transition temperature.

^bMechanical properties are measured by a universal material testing machine in accordance with GB/T 1040.3-2006, and T _S is the tensile strength.

^c. The gas separation performance is tested by VAC-V2 differential pressure gas permeation instrument according to ISO15105-1. The test condition is 1 atmosphere/30°C, and the thickness of the separation membrane sample is 50 μm. The unit of gas permeability coefficient P is barrer, 1 barrer=1×10 ^-10 cm ³ (STP)cm/cm ² s cmHg, selectivity coefficient α=PA/ _{P B .}

Claims (12)

1. A polyimide gas separation membrane for separation and recovery of carbon dioxide, characterized in that, said separation membrane is made from polyimide resin with fluorine-containing benzene side group structure, said polyimide Amine resin has the general structural formula shown in following formula I: Wherein, Ar is selected from any one of the following groups: X is _CH3 or F, Y is H or CH ₃ , L, M, and N are the same or different, and are independently selected from H, F, or CF ₃ , and at least one of L, M, and N is F or CF ₃ , n is an integer of 50-300. 2. The gas separation membrane according to claim 1, characterized in that the number average molecular weight (M _n ) of the polyimide resin is between 50000 and 200000 g/mol. 3. The gas separation membrane according to claim 1 or 2, characterized in that the thickness of the separation membrane is 25-75 μm. 4. a preparation method of the polyimide resin in the gas separation membrane described in any one of claim 1-3, is characterized in that, described method comprises the steps: Under the protection of an inert gas, the aromatic diamine having a fluorine-containing benzene side group structure represented by formula II is dissolved in an organic solvent, and then the aromatic dianhydride represented by formula III is added to obtain the polyimide resin: in, The definition of X, Y, L, M, N and Ar is the same as formula I. 5. The method according to claim 4, characterized in that, after the aromatic diamine shown in formula II and the aromatic dianhydride shown in formula III are stirred until they are all dissolved to obtain a homogeneous solution, then a catalyst and a dehydrating agent are added to heat up to react After the reaction is completed, the dehydrating agent is removed, and after cooling, the precipitant is poured into the polyimide resin to obtain the polyimide resin. 6. The method according to claim 4 or 5, characterized in that the aromatic dianhydride shown in formula III is 4,4'-(hexafluoroisopropyl) diphthalic anhydride (6FDA), 4,4 '-(2,2,2-Trifluoromethyl-1-phenyl-ethylene) diphthalic anhydride (3FDA), 4,4'-[2,2,2-Trifluoromethyl-1-(3 -trifluoromethylphenyl)-ethylene]diphthalic anhydride (HFDA), 4,4'-[2,2,2-trifluoromethyl-1-(3,5-bistrifluoromethylphenyl )-Ethylene]diphthalic anhydride (9FDA), triptycene-2,3,6,7-tetraacid dianhydride (TDA), 1,4-bis(3',4'-dicarboxyphenoxy) Triptyl dianhydride (TODA) or 9,9-bis(3,4-dianhydride phenoxyphenyl)fluorene (BAOFL); The aromatic diamine with fluorine-containing benzene side group structure represented by formula II is α,α-bis(4-amino-3,5-dimethylphenyl)-1-(4'-trifluoromethylphenyl) Methane, α,α-bis(4-amino-3,5-dimethylphenyl)-1-(3',5'-bistrifluoromethylphenyl)methane, α,α-bis(4- Amino-3,5-dimethylphenyl)-1-(4'-fluorophenyl)methane, α,α-bis(4-amino-3,5-dimethylphenyl)-1-(3 ',5'-difluorophenyl)methane, α,α-bis(4-amino-3,5-dimethylphenyl)-1-(3',4',5'-trifluorophenyl) Methane, α,α-bis(4-amino-3,5-dimethylphenyl)-1-(4'-trifluoromethylphenyl)ethane, α,α-bis(4-amino-3 ,5-Dimethylphenyl)-1-(3',5'-bistrifluoromethylphenyl)ethane, α,α-bis(4-amino-3,5-dimethylphenyl) -1-(4'-fluorophenyl)ethane, α,α-bis(4-amino-3,5-dimethylphenyl)-1-(3',5'-difluorophenyl)ethane alkane, α,α-bis(4-amino-3,5-dimethylphenyl)-1-(3',4',5'-trifluorophenyl)ethane, α,α-bis(4 -Amino-3,5-difluorophenyl)-1-(4'-trifluoromethylphenyl)methane, α,α-bis(4-amino-3,5-difluorophenyl)-1- (4'-fluorophenyl)methane, α,α-bis(4-amino-3,5-difluorophenyl)-1-(4'-trifluoromethylphenyl)ethane or α,α- bis(4-amino-3,5-difluorophenyl)-1-(4'-fluorophenyl)ethane. 7. The method according to claim 5, wherein the organic solvent is selected from N-methylpyrrolidone (NMP), γ-butyrolactone, dimethyl sulfoxide (DMSO), N,N-di At least one of methylacetamide (DMAc) and N,N-dimethylformamide (DMF); The catalyst is selected from one of isoquinoline, quinoline, triethylamine or pyridine; Described dehydrating agent is toluene or xylene; The precipitating agent is at least one selected from water, methanol, ethanol, propanol, butanol or isopropanol. 8. The method according to claim 5, characterized in that the molar ratio of the aromatic diamine having a fluorine-containing benzene side group structure to the aromatic dianhydride is 0.95-1.05:1.0; The solid content of the homogeneous solution is 25-40wt.%. The molar ratio of the catalyst to the aromatic dianhydride is 0.05-0.1:1.0; The temperature for the reaction by raising the temperature is 140-180° C.; the time is 8-12 hours. 9. the preparation method of the polyimide gas separation membrane that is used for the separation of carbon dioxide described in any one of claim 1-3 and reclaims, it is characterized in that, described method comprises the steps: Dissolving the above-mentioned polyimide resin with fluorine-containing benzene side group structure in an organic solvent to obtain the resin solution, and then coating the resin solution on the substrate, after drying, immersing in deionized water to peel off, The polyimide gas separation membrane was obtained. 10. the described preparation method of claim 9 is characterized in that, described organic solvent is selected from N-methylpyrrolidone (NMP), gamma-butyrolactone, dimethylsulfoxide (DMSO), N,N-di At least one of methylacetamide (DMAc) and N,N-dimethylformamide (DMF); The substrate is a glass plate or a stainless steel plate; The solid content of the resin solution is 25-45wt.%. In the drying step, the temperature is 80-200° C., and the time is 3-5 hours. 11. The use of the polyimide gas separation membrane according to any one of claims 1-3, which is used for separation and recovery of carbon dioxide. 12. The use according to claim 11, characterized in that the separation and recovery includes the separation of carbon dioxide and methane in biogas, the removal of acid gases including carbon dioxide in natural gas, or the recovery of carbon dioxide in oil field tertiary oil recovery.