阅读说明：本技术 活性分离层表面富集共价有机框架材料的中空纤维复合膜 (Hollow fiber composite membrane with covalent organic framework material enriched on surface of active separation layer ) 是由 潘福生 王梅迪 杨磊鑫 于 2019-11-07 设计创作，主要内容包括：本发明公开了一种活性分离层表面富集共价有机框架材料的中空纤维复合膜。该活性分离层表面富集共价有机框架材料的中空纤维复合膜包括支撑层,以及形成于支撑层至少一侧表面上的活性分离层；其中,所述活性分离层包括高分子膜基质以及负载于高分子膜基质上的共价有机框架材料,所述支撑层包括聚砜中空纤维超滤膜。本发明提供的中空纤维复合膜的活性分离层内共价有机框架材料在表面富集,能够充分发挥其对CO-2优先吸附和强化扩散的优势；同时中空纤维膜的形式具有填充密度高的特点。(The invention discloses a hollow fiber composite membrane with an active separation layer surface enriched with covalent organic framework materials. The hollow fiber composite membrane with the surface enriched with the covalent organic framework material on the active separation layer comprises a supporting layer and an active separation layer formed on the surface of at least one side of the supporting layer; the active separation layer comprises a polymer membrane matrix and a covalent organic framework material loaded on the polymer membrane matrix, and the support layer comprises a polysulfone hollow fiber ultrafiltration membrane. The covalent organic framework material in the active separation layer of the hollow fiber composite membrane provided by the invention is on the surfaceThe flour is enriched and can fully exert the effect on CO 2 Preferential adsorption and diffusion-enhanced advantages; meanwhile, the hollow fiber membrane has the characteristic of high filling density.)

1. The hollow fiber composite membrane with the surface enriched with the covalent organic framework material on the active separation layer is characterized by comprising a support layer and an active separation layer formed on the surface of at least one side of the support layer; the active separation layer comprises a polymer membrane matrix and a covalent organic framework material loaded on the polymer membrane matrix, and the support layer comprises a polysulfone hollow fiber ultrafiltration membrane.

2. The hollow fiber composite membrane with the surface enriched with the covalent organic framework material on the active separation layer according to claim 1, wherein the polymer membrane matrix is block polyether amide resin, and the mass ratio of the block polyether amide resin to the covalent organic framework material is 100: 1-10.

3. The hollow fiber composite membrane with the surface enriched with the covalent organic framework material on the active separation layer according to claim 1, wherein the covalent organic framework material has a two-dimensional lamellar structure, the transverse dimension of the two-dimensional lamellar structure is 100-500 nm, the thickness of the lamellar structure is 1-6 nm, and the pore diameter is 0.6-2 nm.

4. A preparation method of the hollow fiber composite membrane with the surface enriched with the covalent organic framework material of the active separation layer according to any one of claims 1 to 3, is characterized by comprising the following steps:

1) dispersing a covalent organic framework material into a solvent to obtain a dispersion liquid;

2) mixing and stirring the dispersion liquid and the polymer film matrix, and standing to obtain a homogeneous film casting liquid;

3) and soaking the polysulfone hollow fiber ultrafiltration membrane in the homogeneous membrane casting solution, taking out, and drying to obtain the hollow fiber composite membrane with the surface of the active separation layer enriched with the covalent organic framework material.

5. The method according to claim 4, wherein the covalent organic framework material in step 1) is formed by condensation polymerization of 1,3, 5-triacyl trimenol and amino small molecule organic matter; wherein the amino micromolecule organic matter is hydrazine hydrate, p-phenylenediamine, diphenyldiamine or triaminoguanidine hydrochloride.

6. The method according to claim 4, wherein the solvent in step 1) is an aqueous ethanol solution, butanol or isopropanol.

7. The method according to claim 4, wherein the mass ratio of the covalent organic framework material to the solvent in step 1) is 0.001 to 0.005: 1.

8. The method according to claim 4, wherein the polymer film matrix in step 2) is a block polyetheramide resin.

9. The method according to claim 8, wherein the mass ratio of the block polyetheramide resin to the dispersion liquid is 0.01 to 0.1: 1.

10. Use of the hollow fiber composite membrane with the surface enriched with the covalent organic framework material according to any one of claims 1 to 3 in the separation of carbon dioxide and methane.

Technical Field

The invention relates to the technical field of hollow fiber membrane separation. And more particularly, to a hollow fiber composite membrane with an active separation layer surface enriched with covalent organic framework materials.

Background

Methane gas is considered as one of the most potential clean energy sources as a gas fuel with abundant sources, high heat value and convenient transportation. China's methane gas is rich in resources, but contains CO₂When the content of the acid gas is higher, the corrosion of recovery equipment and a conveying pipeline is caused, and the heat value is reduced, so that the gas produced in a gas field or an oil field needs to be pretreated to meet the requirement of conveying CO in natural gas by a pipeline₂The content is less than or equal to 2 percent. At the same time, CO₂Is an important factor causing global warming, and global CO is emitted annually₂The discharge amount exceeds 320 hundred million tons. Therefore, the purification (CO) of methane gas such as natural gas, coal bed gas and the like is realized₂/CH₄Separation) and CO₂The trapping has great economic significance and environmental protection benefit.

For CO₂/CH₄The traditional separation method comprises chemical absorption, temperature swing adsorption, freezing separation and the like, and generally has the problems of high energy consumption, high operating cost and the like. The membrane separation technology is a green and efficient separation technology, has the advantages of high energy efficiency, simple design, easy regulation of membrane components and treatment scale, small occupied space and the like, and draws wide attention. The gas membrane separation technology can utilize the membrane material to realize high adsorption selectivity and realize continuous operation of the separation process, has important technical advantages and cost advantages, and becomes the most interesting methane purification and CO₂One of the trapping techniques. Development of CO with high permeability, high selectivity, high stability and easy scale-up preparation₂The separation membrane material is critical to its application. Cellulose acetate membranes generally adopted in the industry at present have good stability, but have low permeability and selectivity; is considered to beAlthough the polyimide film with good application prospect has high initial performance, the aging problem is serious in the using process, and the permeability attenuation is fast. Therefore, the development of a catalyst for CO is urgently needed₂The membrane material with higher specificity is transferred, the physical and chemical structure which is suitable for the transfer process is designed, and the problems of plasticization, aging and the like in the use process of the membrane are solved.

Covalent organic framework materials (COF) as a new class of porous materials with large specific surface areas (up to 10000 m)²The method has the advantages of high porosity (up to 90%), regular and ordered micropore structure, and easy regulation of pore structure and surface functional group, and is particularly suitable for separating gas mixtures with small structural difference. However, the difficulty of preparing a COF into a complete and defect-free separation membrane is high at present, and the large-scale preparation of the COF is difficult to realize. The COF and the high polymer material are blended to prepare the hybrid film, so that the problem of difficult molding can be solved. In addition, COF is obtained by covalent bonding of organic monomers, has the inherent properties of organic materials, has the advantages of good compatibility with high molecular materials and few interface defects, and is more suitable as a filler of a hybrid membrane than zeolite, Metal Organic Framework (MOF) and the like. However, in the hybrid film, the COF material is embedded in the polymer body, and the pore structure thereof is difficult to sufficiently exert its effect.

Therefore, the invention provides a hollow fiber composite membrane with an active separation layer surface enriched with covalent organic framework materials, a preparation method and application thereof, so as to solve the problems.

Disclosure of Invention

The invention aims to provide a hollow fiber composite membrane with an active separation layer surface enriched with covalent organic framework materials, a preparation method and application thereof; aiming at the prior art, in order to simultaneously improve the permeability, selectivity and stability of the membrane, the COF-macromolecule hybrid material is coated on the surface of the hollow fiber supporting layer, so that the enrichment of the COF material on the surface of a macromolecule main body is realized, the multiple advantages of the separation characteristic of the COF material, easy membrane formation of the macromolecule material and high filling density of the hollow fiber membrane are integrated, and the invention has good application prospect.

In order to achieve the purpose, the invention adopts the following technical scheme:

a hollow fiber composite membrane with an active separation layer surface enriched with covalent organic framework materials comprises a support layer and an active separation layer formed on at least one side surface of the support layer; wherein the content of the first and second substances,

the active separation layer comprises a polymer film matrix and a covalent organic framework material loaded on the polymer film matrix.

The hollow fiber composite membrane with the surface of the active separation layer enriched with the covalent organic framework material utilizes a large amount of amino groups of COF materials in the active separation layer to be used as transfer promotion sites to promote CO₂Preferential adsorption and rapid diffusion of molecules; the regular pore channel structure of the COF material is beneficial to CO₂Rapid diffusion of (2); the polymer matrix in the active separation layer is utilized to provide excellent film forming performance; the use of a hollow fiber support layer provides a high packing density. In addition, the COF material is formed by connecting organic ligands through covalent bonds, has good stability and has good interface compatibility with macromolecules.

Preferably, the support layer comprises a polysulfone hollow fiber ultrafiltration membrane.

Preferably, the polymer film matrix is block polyether amide resin (Pebax), and the mass ratio of the block polyether amide resin to the covalent organic framework material is 100: 1-10.

Preferably, the covalent organic framework material is formed by condensation polymerization of 1,3, 5-triacyl phloroglucinol and amino micromolecule organic matter; wherein the amino micromolecule organic matter is hydrazine hydrate, p-phenylenediamine, diphenyldiamine or triaminoguanidine hydrochloride.

Preferably, the molar ratio of the 1,3, 5-triacyl phloroglucinol to the amino micromolecule organic matter is 1-2: 1-2; further, in certain embodiments of the present invention, for example, the molar ratio of the 1,3, 5-triacyl phloroglucinol to the amino small molecule organic is 2:1, 1:1, or 1: 2.

Preferably, the covalent organic framework material has a two-dimensional lamellar structure, the transverse dimension of the covalent organic framework material is 100-500 nm, the thickness of the lamellar is 1-6 nm, and the aperture is 0.6-2 nm.

The invention also provides a preparation method of the hollow fiber composite membrane with the surface of the active separation layer enriched with the covalent organic framework material, which comprises the following steps:

1) dispersing a covalent organic framework material into a solvent to obtain a dispersion liquid;

2) mixing and stirring the dispersion liquid and the polymer film matrix, and standing for 6-18h to obtain a homogeneous film casting liquid;

3) and soaking the polysulfone hollow fiber ultrafiltration membrane in the homogeneous membrane casting solution, taking out, and drying to obtain the hollow fiber composite membrane with the surface of the active separation layer enriched with the covalent organic framework material.

In the hollow fiber composite membrane prepared by the method, the concentration of the organic framework material in the active separation layer is gradually reduced towards the surface of the polysulfone hollow fiber supporting layer along the outer surface, and the organic framework material is used for CO₂/CH₄Separating, at 25 deg.C, raw material gas CO₂/CH₄(30/70 vol%) the permeability coefficient was 126 and the separation factor was 32.

Preferably, the covalent organic framework material in the step 1) is formed by condensation polymerization of 1,3, 5-triacyl phloroglucinol and amino micromolecule organic matter; wherein the amino micromolecule organic matter is hydrazine hydrate, p-phenylenediamine, diphenyldiamine or triaminoguanidine hydrochloride.

Preferably, the preparation of the covalent organic framework material in step 1) comprises the following steps:

i) dissolving 1,3, 5-trimethyl acyl phloroglucinol in 1,3, 5-trimethyl benzene or ethanol to obtain a solution A;

ii) adding the amino micromolecule organic matter into the solution A, and reacting under a heating condition to obtain a product A; washing and drying the product A to obtain a product B; wherein the amino micromolecule organic matter is hydrazine hydrate, p-phenylenediamine, diphenyldiamine or triaminoguanidine hydrochloride;

iii) adding 0.1-0.5 ml of alcohol solvent into the product B, and grinding to obtain a product C;

iv) dissolving the product C in an alcohol solvent, washing, and drying to obtain the covalent organic framework material.

Preferably, the concentration of the solution A in the step i) is 0.007-0.021 g/mL.

Preferably, the temperature of the heating condition in step ii) is 120 ℃, and the reaction time is 48 h.

Preferably, the washing and drying of the product A in the step ii) are carried out by sequentially carrying out centrifugal washing on the product A by using anhydrous tetrahydrofuran, anhydrous acetone and anhydrous dichloromethane, and then carrying out vacuum drying at 120 ℃ for 24 h.

Preferably, the time for said milling in step iii) is 1 h.

Preferably, the drying in step iv) is vacuum drying at 40 ℃ for 24 h.

Preferably, both the alcoholic solvent in step iv) and step iv) is methanol.

Preferably, the solvent in step 1) is an aqueous ethanol solution, butanol or isopropanol.

Preferably, the mass ratio of the covalent organic framework material to the solvent in the step 1) is 0.001-0.005: 1.

Preferably, the polymer film matrix in step 2) is a block polyether amide resin.

Preferably, the mass ratio of the polymer film matrix to the dispersion liquid in the step 2) is 0.01-0.1: 1.

Preferably, the stirring conditions in step 2) are: stirring for 6-8 h at the rotating speed of 300r/min at the temperature of 60 ℃.

Preferably, the soaking time in the step 3) is 10-30 min.

Preferably, the drying conditions in step 3) are 25 ℃ and 40 RH% suspension drying for 24 h.

The invention also provides an application of the hollow fiber composite membrane with the surface of the active separation layer enriched with the covalent organic framework material in the separation of carbon dioxide and methane.

The invention deposits the macromolecule-covalent organic framework hybrid material on the hollow fiber substrate to prepare the hollow fiber composite membrane with the active separation layer being the macromolecule-covalent organic framework material; in addition, the covalent organic framework material is matched with the membrane preparation solvent to realize the enrichment of the covalent organic framework material on the surface of the active separation layer of the hollow fiber composite membrane, thereby improving the membraneThe separation performance of (a); the separation membrane with the above structure characteristics can be applied to CO₂/CH₄And (5) separating.

In addition, unless otherwise specified, any range recited herein includes any value between the endpoints and any sub-range defined by any value between the endpoints or any value between the endpoints.

The invention has the following beneficial effects:

the covalent organic framework material in the active separation layer of the hollow fiber composite membrane provided by the invention is enriched on the surface, and can give full play to the CO₂Preferential adsorption and diffusion-enhanced advantages; meanwhile, the form of the hollow fiber membrane has the characteristic of high filling density; the membrane preparation process is simple and convenient, the controllability is strong, the raw materials are easy to obtain, and the method is universal; the obtained membrane is used for CO₂/CH₄Separation system of, to CO₂The molecule has high permeation flux, high selectivity and good operation stability.

Drawings

The following describes embodiments of the present invention in further detail with reference to the accompanying drawings.

FIG. 1 shows an electron microscope image of the surface structure of the hollow fiber composite membrane prepared in example 1 of the present invention.

FIG. 2 shows an electron microscope image of the surface structure of the hollow fiber composite membrane prepared in example 2 of the present invention.

FIG. 3 shows an electron microscope image of the surface structure of the hollow fiber composite membrane prepared in example 3 of the present invention.

FIG. 4 is an electron microscope image showing the cross-sectional structure of a hollow fiber composite membrane obtained in example 3 of the present invention

FIG. 5 is a diagram showing the distribution of nitrogen in the active separation layer of the hollow fiber composite membrane obtained in example 3 of the present invention.

FIG. 6 is an electron microscope image of the surface structure of the hollow fiber composite membrane prepared in example 4 of the present invention.

FIG. 7 is an electron microscope image showing the surface structure of the hollow fiber composite membrane according to comparative example 1 of the present invention.

Detailed Description

In order to more clearly illustrate the invention, the invention is further described below in connection with preferred embodiments. It is to be understood by persons skilled in the art that the following detailed description is illustrative and not restrictive, and is not to be taken as limiting the scope of the invention.

In the invention, the preparation method is a conventional method if no special description is provided; the starting materials used are commercially available from published sources unless otherwise specified.

Example 1

The embodiment provides a preparation method of a hollow fiber composite membrane with an active separation layer surface enriched with a covalent organic framework material, which comprises the following steps:

step one, preparing a covalent organic framework material:

dissolving 0.21g of 1,3, 5-trimethylacylphloroglucinol in 30mL of a 1,3, 5-trimethylbenzene/ethanol (v: v ═ 1:1) solvent to form a solution A with a mass volume concentration of 0.007 g/mL; then 0.032g of hydrazine hydrate is added to the solution A; sealing the system in a nitrogen environment, heating to 120 ℃, and reacting for 48 hours to obtain a reddish brown precipitate; centrifugally washing the product by using anhydrous tetrahydrofuran, anhydrous acetone and anhydrous dichloromethane in sequence, and then drying the product in vacuum at 120 ℃ for 24 hours to obtain red powder; placing the dried product into a mortar, adding 0.1ml of methanol drop by drop, grinding for 1h, dissolving the ground product into methanol, centrifugally washing, and drying in vacuum at 40 ℃ for 24h to obtain a product, namely the covalent organic framework TpHz;

step two, preparing a hollow fiber composite membrane with covalent organic framework gradient distribution:

dispersing 0.05g of the covalent organic framework material TpHz prepared in the step one into 10g of solvent butanol, and performing ultrasonic dispersion for 30 minutes to obtain a dispersion liquid;

adding 1.0g of Pebax into the obtained dispersion liquid, mixing to obtain a solution B, stirring at the temperature of 60 ℃ for 6 hours at the rotating speed of 300r/min, standing for 6 hours, and defoaming to obtain a homogeneous membrane casting liquid;

and (2) immersing the polysulfone hollow fiber ultrafiltration membrane into the homogeneous membrane casting solution, soaking for 30min, taking out, and then hanging and drying at 25 ℃ and 40 RH% for 24h to obtain the hollow fiber composite membrane with the surface of the active separation layer enriched with the covalent organic framework material.

Fig. 1 shows an electron microscope image of the surface structure of the hollow fiber composite membrane prepared in this example, and as can be seen from fig. 1, the surface of the prepared hollow fiber composite membrane is composed of Pebax host material and covalent organic framework material particles distributed therein.

Example 2

The embodiment provides a preparation method of a hollow fiber composite membrane with an active separation layer surface enriched with a covalent organic framework material, which comprises the following steps:

step one, preparing a covalent organic framework material:

dissolving 0.42g of 1,3, 5-trimethylacylphloroglucinol in 30mL of a 1,3, 5-trimethylbenzene/ethanol (v: v ═ 1:1) solvent to form a solution A with a mass volume concentration of 0.007 g/mL; then 0.109g of hydrated p-phenylenediamine was added to solution A; sealing the system in a nitrogen environment, heating to 120 ℃, and reacting for 48 hours to obtain a reddish brown precipitate; centrifugally washing the product by using anhydrous tetrahydrofuran, anhydrous acetone and anhydrous dichloromethane in sequence, and then drying the product in vacuum at 120 ℃ for 24 hours to obtain red powder; placing the dried product in a mortar, adding 0.4ml of methanol, grinding for 1h, dissolving the ground product in methanol, centrifugally washing, and drying in vacuum at 40 ℃ for 24h to obtain a product, namely the covalent organic framework TpPa;

step two, preparing a hollow fiber composite membrane with covalent organic framework gradient distribution:

dispersing 0.10g of covalent organic framework material TpPa prepared in the step one into 10g of solvent isopropanol, and performing ultrasonic dispersion for 30 minutes to obtain dispersion liquid;

adding 0.7g of Pebax into the obtained dispersion liquid, mixing to obtain a solution B, stirring at the temperature of 60 ℃ for 6 hours at the rotating speed of 300r/min, standing for 18 hours, and defoaming to obtain a homogeneous membrane casting liquid;

and (2) immersing the polysulfone hollow fiber ultrafiltration membrane into the homogeneous membrane casting solution, soaking for 20min, taking out, and then hanging and drying at 25 ℃ and 40 RH% for 24h to obtain the hollow fiber composite membrane with the surface of the active separation layer enriched with the covalent organic framework material.

Fig. 2 shows an electron microscope image of the surface structure of the hollow fiber composite membrane prepared in this example, and as can be seen from fig. 2, the surface of the prepared hollow fiber composite membrane is composed of Pebax host material and covalent organic framework material particles distributed therein, and the content of the particles is increased.

Example 3

The embodiment provides a preparation method of a hollow fiber composite membrane with an active separation layer surface enriched with a covalent organic framework material, which comprises the following steps:

step one, preparing a covalent organic framework material:

dissolving 0.63g of 1,3, 5-trimethylacylphloroglucinol in 30mL of a 1,3, 5-trimethylbenzene/ethanol (v: v ═ 1:1) solvent to form a solution A with a mass volume concentration of 0.007 g/mL; then 0.185g of biphenyldiamine was added to the solution A; sealing the system in a nitrogen environment, heating to 120 ℃, and reacting for 48 hours to obtain a reddish brown precipitate; centrifugally washing the product by using anhydrous tetrahydrofuran, anhydrous acetone and anhydrous dichloromethane in sequence, and then drying the product in vacuum at 120 ℃ for 24 hours to obtain red powder; placing the dried product in a mortar, adding 0.2ml of methanol, grinding for 1h, dissolving the ground product in methanol, centrifugally washing, and drying in vacuum at 40 ℃ for 24h to obtain a product, namely the covalent organic framework TpBD;

step two, preparing a hollow fiber composite membrane with covalent organic framework gradient distribution:

dispersing 0.15g of the covalent organic framework material TpBD prepared in the step one into 10g of a solvent 50 wt% ethanol-water solvent, and performing ultrasonic dispersion for 30 minutes to obtain a dispersion liquid;

adding 0.3g of Pebax into the obtained dispersion liquid, mixing to obtain a solution B, stirring at the temperature of 60 ℃ for 6 hours at the rotating speed of 300r/min, standing for 12 hours, and defoaming to obtain a homogeneous membrane casting liquid;

soaking the polysulfone hollow fiber ultrafiltration membrane in the homogeneous membrane casting solution for 10min, taking out, and then hanging and drying at 25 ℃ and 40 RH% for 24h to obtain the hollow fiber composite membrane with the surface of the active separation layer enriched with the covalent organic framework material.

Fig. 3 shows an electron microscope image of the surface structure of the hollow fiber composite membrane prepared in this example, and as can be seen from fig. 3, the surface of the prepared hollow fiber composite membrane is composed of Pebax host material and covalent organic framework material particles distributed therein, and the content of the particles is further increased.

Fig. 4 shows an electron microscope image of the cross-sectional structure of the hollow fiber composite membrane prepared in this example, and it can be seen from fig. 4 that the prepared hollow fiber composite membrane is composed of a porous support layer and a dense active separation layer, and the dense active separation layer is well bonded on the support layer without obvious delamination.

Fig. 5 shows a distribution diagram of nitrogen element in the active separation layer of the hollow fiber composite membrane prepared in this example, and it can be seen from fig. 5 that the content of the covalent organic framework material containing nitrogen element in the active separation layer is decreased in a gradient from the membrane surface to the inside.

Example 4

The embodiment provides a preparation method of a hollow fiber composite membrane with an active separation layer surface enriched with a covalent organic framework material, which comprises the following steps:

step one, preparing a covalent organic framework material:

dissolving 0.42g of 1,3, 5-trimethylacylphloroglucinol in 30mL of a 1,3, 5-trimethylbenzene/ethanol (v: v ═ 1:1) solvent to form a solution A with a mass volume concentration of 0.007 g/mL; then 0.140g of triaminoguanidine hydrochloride is added into the solution A; sealing the system in a nitrogen environment, heating to 120 ℃, and reacting for 48 hours to obtain a reddish brown precipitate; centrifugally washing the product by using anhydrous tetrahydrofuran, anhydrous acetone and anhydrous dichloromethane in sequence, and then drying the product in vacuum at 120 ℃ for 24 hours to obtain red powder; placing the dried product into a mortar, adding 0.5ml of methanol, grinding for 1h, dissolving the ground product into methanol, centrifugally washing, and drying in vacuum at 40 ℃ for 24h to obtain a product, namely the covalent organic framework (TpTG);

step two, preparing a hollow fiber composite membrane with covalent organic framework gradient distribution:

dispersing 0.20g of the covalent organic framework material TpTG prepared in the step one into 10g of solvent butanol, and performing ultrasonic dispersion for 30 minutes to obtain a dispersion liquid;

adding 0.2g of Pebax into the obtained dispersion liquid, mixing to obtain a solution B, stirring at the temperature of 60 ℃ for 6 hours at the rotating speed of 300r/min, standing for 6 hours, and defoaming to obtain a homogeneous membrane casting liquid;

soaking the polysulfone hollow fiber ultrafiltration membrane in the homogeneous membrane casting solution for 10min, taking out, and then hanging and drying at 25 ℃ and 40 RH% for 24h to obtain the hollow fiber composite membrane with the surface of the active separation layer enriched with the covalent organic framework material.

Fig. 6 shows an electron microscope image of the surface structure of the hollow fiber composite membrane prepared in this example, and as can be seen from fig. 6, the surface of the prepared hollow fiber composite membrane is composed of Pebax host material and covalent organic framework material particles distributed therein, the content of the covalent organic framework particles is further increased, and obvious agglomeration phenomenon exists among the particles.

Comparative example 1

The comparative example provides a preparation of a hollow fiber composite membrane, comprising the steps of:

adding 0.5g of Pebax into 10ml of n-butyl alcohol, stirring at the temperature of 60 ℃ for 6h at the rotating speed of 300r/min, standing for 12h, and defoaming to obtain a homogeneous membrane casting solution;

soaking the polysulfone hollow fiber ultrafiltration membrane in the homogeneous membrane casting solution for 10min, taking out, and then hanging and drying at 25 ℃ and 40 RH% for 24h to obtain the hollow fiber composite membrane.

Fig. 7 shows an electron microscope image of the surface structure of the hollow fiber composite membrane prepared in this comparative example, and it can be seen from fig. 7 that the prepared hollow fiber composite membrane has a smooth surface and no particles of the covalent organic framework material are present.

Test example 1

This test example provides CO of a hollow fiber composite membrane₂/CH₄The separation performance testing method comprises the following steps:

application of hollow fiber composite membrane to CO₂/CH₄Separating, namely separating raw material gas CO at 25 DEG C₂/CH₄(30/70 vol%) was first humidified in a humidifying tank (water temperature: 30 ℃) to a relative humidity of 98% or more, and then the humidified starting material gas was passed through a buffer tank to remove entrained condensed water, while the purge gas was directly subjected to the humidifying operation at room temperature. The effective test area of the membrane pool is 12.5cm²The volume flow rates of the feed gas and the purge gas were measured using mass flow meters, and the test temperature was adjusted by a constant temperature water bath. The pressure of the raw material gas is controlled at 0.2MPa, and the volume flow rate is controlled at 60 mL/min. Selecting N₂As the purge gas, the operation pressure was normal pressure, and the volume flow rate was controlled to 30 mL/min. The raw material gas of the sweep gas which permeates the membrane enters Agilent 6820 type gas chromatography to measure the composition,and the raw material gas is discharged after passing through the membrane tank. The results of the membrane separation performance test are shown in table 1.

The results show that: example 3 the prepared hollow fiber composite membrane showed the highest permeability coefficient and separation factor.

TABLE 1 permeation coefficient and separation factor comparison of membranes made in the examples of the invention with comparative membranes

It should be understood that the above-mentioned embodiments of the present invention are only examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention, and it will be obvious to those skilled in the art that other variations or modifications may be made on the basis of the above description, and all embodiments may not be exhaustive, and all obvious variations or modifications may be included within the scope of the present invention.