阅读说明：本技术 一种二氧化碳分离膜及其应用 (Carbon dioxide separation membrane and application thereof ) 是由 谭叶梅 于 2021-10-20 设计创作，主要内容包括：本发明公开了一种二氧化碳分离膜及其应用,该二氧化碳分离膜包括依次设置的支撑层、纳米粒子复合层和聚合物层；所述二氧化碳分离膜的二氧化碳渗透率大于3400Barrer,CO-(2)/N-(2)选择系数大于45。本发明制得的二氧化碳分离膜为三层结构,通过将纳米粒子和第一聚合物搭配形成纳米粒子复合层解决了相关技术中混合基质膜中因纳米粒子分散不均匀或团聚导致的缺陷问题；同时还解决了传统混合基质膜中因聚合物组分与无机纳米粒子相界面不匹配而导致的选择性降低问题。本发明二氧化碳分离膜的对二氧化碳选择性高且渗透率高。(The invention discloses a carbon dioxide separation membrane and application thereof, wherein the carbon dioxide separation membrane comprises a supporting layer, a nano particle composite layer and a polymer layer which are sequentially arranged; the carbon dioxide permeability of the carbon dioxide separation membrane is more than 3400Barrer, CO 2 /N 2 The selection factor is greater than 45. The carbon dioxide separation membrane prepared by the invention has a three-layer structure, and nanoparticles are preparedThe nano particle composite layer formed by matching the seed and the first polymer solves the problem of defects caused by uneven dispersion or agglomeration of nano particles in the mixed matrix film in the related technology; meanwhile, the problem of selectivity reduction caused by mismatching of polymer components and inorganic nano particle phase interfaces in the traditional mixed matrix membrane is solved. The carbon dioxide separation membrane has high selectivity and permeability to carbon dioxide.)

1. A carbon dioxide separation membrane characterized by: the nano particle composite layer comprises a supporting layer, a nano particle composite layer and a polymer layer which are arranged in sequence; the carbon dioxide permeability of the carbon dioxide separation membrane is more than 3400Barrer, CO₂/N₂The selection coefficient is greater than 45;

the nano particle composite layer is prepared from nano particles and a first polymer;

the mass percentage of the nano particles in the nano particle composite layer is 90% -99.9%;

the nanoparticles comprise surface-modified nanoparticles;

the surface-modified nanoparticles comprise at least one of crown ether-modified nanoparticles or amino-modified nanoparticles;

the preparation method of the carbon dioxide separation membrane comprises the following steps:

s1, preparing a casting solution:

dispersing the nanoparticles in an organic solvent I to prepare a nanoparticle dispersion liquid;

adding the first polymer into the nanoparticle dispersion liquid to prepare a casting solution I;

adding the second polymer into an organic solvent II to prepare a casting solution II;

s2, coating the casting solution:

coating a casting solution I on the surface of the supporting layer, curing for the first time, coating a casting solution II after drying for the first time, curing again, and drying again; thus obtaining the carbon dioxide separation membrane.

2. The carbon dioxide separation membrane according to claim 1, characterized in that: the supporting layer is made of fiber cloth; the material of the fiber cloth comprises at least one of polypropylene, polyacrylonitrile, carbon fiber, polyethylene terephthalate, aramid fiber, polyether ether ketone, polyaryletherketone and polyvinyl alcohol.

3. The carbon dioxide separation membrane according to claim 1, characterized in that: the nanoparticles comprise at least one of molecular sieves, MOFs, graphene, carbon nanotubes, silicones, and metal oxides;

the first polymer comprises at least one of polyvinylidene fluoride, polysulfone, polyimide, amino polyaryletherketone, polyvinyl alcohol, polyaramide, modified polyetheretherketone, polyisophthaloyl metaphenylene diamine and polyether type oxygen-enriched polymer.

4. The carbon dioxide separation membrane according to claim 1, characterized in that: the polymer layer is prepared from a second polymer; the second polymer comprises at least one of polyvinylidene fluoride, polysulfone, polyimide, amino polyaryletherketone, polyvinyl alcohol, polyaramide, modified polyetheretherketone and polyether oxygen-enriched polymer.

5. The carbon dioxide separation membrane according to claim 1, characterized in that: the particle size of the nanoparticles is 1 nm-100 nm.

6. The carbon dioxide separation membrane according to claim 1, characterized in that: the thickness of the polymer layer is 0.1-5 μm.

7. The carbon dioxide separation membrane according to claim 1, characterized in that: the thickness of the nano particle composite layer is 1-50 μm.

8. Use of the carbon dioxide separation membrane of any one of claims 1 to 7 for carbon capture and carbon enrichment.

Technical Field

The invention relates to the technical field of membrane separation, in particular to a carbon dioxide separation membrane and application thereof.

Background

Global warming caused by greenhouse effect has becomeThe focus of global attention. In recent years, carbon emission generated by energy consumption is still at a higher level and maintains a faster growth trend, and the carbon emission reduction strength needs to be enhanced. For reducing CO₂The emission of the coal-fired power plant, the global warming trend is slowed down, and economic, efficient and large-scale CO of the coal-fired power plant is developed₂The technologies of emission reduction and enrichment separation are not slow.

CO in related art₂The most promising approach to emission reduction is the CCUS (carbon capture, utilization and sequestration) technology. It is generally accepted that chemical absorption is one of the most efficient methods in the carbon capture process, and finding a suitable absorbent is the key to chemical absorption, but the desorption process still faces the problem of large energy loss. Although physical adsorption is easy to regenerate, the adsorption capacity is limited and the selectivity is poor. For this reason, the development of an advanced carbon capture and separation process and material with high selectivity, high efficiency and high stability is the key to solving the current carbon emission problem.

Membrane separation technology is receiving more and more extensive attention and application as an emerging means for carbon capture and separation. CO 2₂Separation membrane materials have also been developed greatly as a core element of membrane separation technology.

CO₂The gas separation membrane mainly comprises an ether type oxygen-enriched polymer membrane, a cross-linked ionic polymer gel membrane, a polyion liquid membrane, a polytetrafluoroethylene membrane, a thermal rearrangement polymer membrane, a glassy polymer membrane containing iptycene (cyclic triptycene) block, other non-reactive polymer membranes, an amino-containing polyaryletherketone membrane, a polyaramid membrane, a mixed matrix membrane and the like. But existing CO₂The gas separation membrane has the problems of low pure polymer transmittance, no high temperature resistance and poor corrosion resistance, and the application of the gas separation membrane is greatly limited. Although the membrane carbon dioxide separation technology has been developed greatly in terms of membrane materials and separation processes, the problems of low separation efficiency, low selectivity, high cost, insufficient large-scale application and the like still exist. From the aspect of film material research, the mixed matrix type film material has more problems in the aspects of preparation process, nanoparticle structural property construction, blending and combining uniformity, phase interface matching, polymer compatibility and the like. Is embodied inThe following aspects:

(1) in the process of film forming, the nano particles are poor in dispersion uniformity in the mixed matrix film and easy to agglomerate;

(2) the uniformity of the size of the nano particles is poor;

(3) the poor matching between the nanoparticle interface and the polymer interface leads to membrane body defects, thereby reducing the separation efficiency of the membrane;

(4) due to poor dispersion uniformity, defect-free large-scale preparation of the blended matrix gas separation membrane is difficult to realize on a large scale, and large-scale application is limited;

(5) the inhibition effect of the simple blending mode on the structural characteristics of the nano particles is difficult to solve, and the separation efficiency of the inorganic nano particles in the membrane body is greatly reduced.

The technical problems are generally existed in various mixed matrix gas separation membranes developed at present, and further improvement and large-scale application of the performance of the gas separation membrane material are seriously restricted.

Therefore, it is required to develop a carbon dioxide separation membrane having a stronger selectivity and a higher permeability than the conventional carbon dioxide separation membrane.

Disclosure of Invention

The invention provides a carbon dioxide separation membrane for solving the problems in the prior art, and the carbon dioxide separation membrane has strong selectivity and high permeability.

The invention also provides a preparation method of the carbon dioxide separation membrane.

The invention also provides application of the carbon dioxide separation membrane in carbon capture and carbon enrichment.

The invention provides a carbon dioxide separation membrane in a first aspect, which comprises a supporting layer, a nano particle composite layer and a polymer layer which are sequentially arranged; the carbon dioxide permeability of the carbon dioxide separation membrane is more than 3400Barrer, CO₂/N₂The selection factor is greater than 45.

According to at least one embodiment of the invention, the following beneficial effects are achieved:

and the nano particle composite layer is used for carrying out composite treatment on the nano particles and the first polymer, so that the selectivity of the carbon dioxide separation membrane is improved. The main functions of the polymer layer are:

a. providing a high permeability selective layer for the carbon dioxide separation membrane by controlling the thickness of the layer;

b. the defects caused by nonuniform dispersity or agglomeration in the nanoparticle composite layer are shielded by utilizing the high continuous integrity of the polymer layer, so that the overall performance of the separation membrane is improved, and the preparation difficulty of the nanoparticle composite layer is reduced.

According to some embodiments of the invention, the carbon dioxide separation membrane has a carbon dioxide permeability greater than 3800 Barrer.

According to some embodiments of the invention, the carbon dioxide separation membrane has a carbon dioxide permeability greater than 4000 Barrer.

According to some embodiments of the invention, the carbon dioxide separation membrane has a CO content₂/N₂The selection factor is greater than 60.

According to some embodiments of the invention, the carbon dioxide separation membrane has a CO content₂/N₂The selection factor is greater than 90.

According to some embodiments of the invention, the fibrous cloth is a porous fibrous cloth.

According to some embodiments of the invention, the porous fiber cloth has a pore size of 0.1 μm to 2 μm.

According to some embodiments of the invention, the support layer has a thickness of 10 μm to 200 μm.

According to some embodiments of the invention, the support layer has a thickness of 30 μm to 150 μm.

According to some embodiments of the present invention, the material of the fiber cloth includes at least one of polypropylene, polyacrylonitrile, carbon fiber, polyethylene terephthalate, aramid, polyetheretherketone, polyaryletherketone, and polyvinylalcohol.

According to some embodiments of the invention, the nanoparticle composite layer is prepared from nanoparticles and a first polymer.

The first polymer provides an adhesive effect for the nanoparticle composite layer, so that the nanoparticles form a complete continuous and stable functional layer, the unique properties of the nanoparticles are kept to the maximum extent, and the effects of high permeability and high selectivity of the nanoparticles are exerted. And simultaneously overcomes the problem of low permeability caused by high content of polymer components.

By modifying the surface of the nano particles, the compatibility of the nano particles and the first polymer is improved, so that the selectivity of the carbon dioxide separation membrane is improved.

According to some embodiments of the invention, the nanoparticles have a particle size of 1nm to 100 nm.

According to some embodiments of the invention, the nanoparticles have a particle size of 1nm to 20 nm.

According to some embodiments of the invention, the nanoparticles comprise at least one of molecular sieves, MOFs, graphene, carbon nanotubes, silicones, crown ethers and metal oxides.

According to some embodiments of the invention, the molecular sieve comprises an amino group-containing molecular sieve.

According to some embodiments of the invention, the graphene comprises amino-grafted graphene.

According to some embodiments of the invention, the carbon nanotubes comprise amino-grafted carbon nanotubes.

According to some embodiments of the invention, the silicone comprises a cage silicone.

According to some embodiments of the invention, the crown ether comprises an amino-containing caged crown ether.

According to some embodiments of the invention, the metal oxide comprises at least one of alumina, zirconia, and titania.

According to some embodiments of the invention, the nanoparticles comprise surface-modified nanoparticles.

According to some embodiments of the invention, the surface-modified nanoparticles comprise at least one of crown ether-modified nanoparticles or amino-modified nanoparticles.

According to some embodiments of the invention, the crown ether modified nanoparticle comprises a crown ether modified graphene.

According to some embodiments of the invention, the amino-modified nanoparticle comprises an amino-modified nanoscale molecular sieve.

According to some embodiments of the invention, the surface-modified nanoparticles comprise at least one of caged crown ether adsorption-modified graphene and DL-2-amino-1-butanol adsorption-modified ZSM-5 (Zeolite Socony mobile-5) nanoscale molecular sieves.

According to some embodiments of the invention, the caged crown ether adsorption-modified graphene comprises 18-crown-6 modified graphene.

According to some embodiments of the invention, the first polymer comprises at least one of polyvinylidene fluoride, polysulfone, polyimide, aminopolyaryletherketone, polyvinyl alcohol, polyaramid, modified polyetheretherketone, polyisophthaloyl metaphenylene diamine, and polyether-type oxygen-enriched polymer.

According to some embodiments of the invention, the polysulfone comprises polyethersulfone.

According to some embodiments of the invention, the polyether oxygen-enriched polymer comprises polyethylene glycol methyl ether.

According to some embodiments of the invention, the mass fraction of the nanoparticles in the nanoparticle composite layer is between 90% and 99.9%.

According to some embodiments of the invention, the nanoparticle composite layer has a thickness of 1 μm to 50 μm.

According to some embodiments of the invention, the polymer layer has a thickness of 0.1 μm to 5 μm.

By controlling the thickness of each layer, the problem of low permeability of the mixed matrix membrane in the related art caused by higher polymer component of the membrane body or thicker membrane body is solved.

The gas permeability is greatly reduced due to the fact that the thickness of each layer is too high, the precise slit coating is difficult to implement when the thickness is too low, the risk of defect generation is increased, and therefore the selection coefficient is reduced.

According to some embodiments of the invention, the polymer layer is prepared from a second polymer.

According to some embodiments of the invention, the second polymer comprises at least one of polyvinylidene fluoride, polysulfone, polyimide, aminopolyaryletherketone, polyvinyl alcohol, polyaramid, modified polyetheretherketone, and polyether oxygen-enriched polymer.

According to some embodiments of the invention, the polysulfone comprises polyethersulfone.

According to some embodiments of the invention, the polyether oxygen-enriched polymer comprises polyethylene glycol methyl ether.

According to some embodiments of the invention, the first polymer and the second polymer are the same or different.

The second aspect of the present invention provides the above method for separating a carbon dioxide separation membrane, comprising the steps of:

mixing the nanoparticles and a first polymer to obtain a nanoparticle composite layer casting solution;

coating the nano particle composite layer casting solution on a supporting layer, and curing to obtain a nano particle composite layer;

and coating a second polymer on the cured nano particle composite layer, and drying to obtain the carbon dioxide separation membrane.

According to some embodiments of the invention, the temperature of the curing is from 10 ℃ to 30 ℃.

According to some embodiments of the invention, the temperature of the curing is from 10 ℃ to 20 ℃.

According to some embodiments of the invention, the temperature of the curing is from 15 ℃ to 20 ℃.

According to some embodiments of the invention, the temperature of the drying is from 50 ℃ to 150 ℃.

According to some embodiments of the present invention, the method for preparing a carbon dioxide separation membrane comprises the steps of:

s1, preparing a casting solution:

dispersing the nanoparticles in an organic solvent I to prepare a nanoparticle dispersion liquid;

adding the first polymer into the nanoparticle dispersion liquid to prepare a casting solution I;

adding the second polymer into an organic solvent II to prepare a casting solution II;

s2, coating the casting solution:

and coating the casting solution I on the surface of the supporting layer, curing for the first time, drying for the first time, coating the casting solution II, curing again, and drying again.

The preparation method solves the problem that the large-scale preparation is limited due to the immaturity of the nanoparticle dispersion process of the mixed matrix membrane in the related technology.

According to some embodiments of the invention, the stirring rate during dispersion of the nanoparticles is 5000 rmp-10000 rpm.

According to some embodiments of the invention, the casting solution I needs to be defoamed, and the defoaming pressure is 50kPa to 80 kPa.

The method adopts the dispersion effect of high-speed homogenization and precise filtration technology (the filtration precision of precise filtration is 1-2 mu m) to fully disperse the nano particles in the nano particle membrane casting solution; meanwhile, the existence of a small amount of polymer components in the nanoparticle membrane casting solution is beneficial to preventing the agglomeration of the nanoparticles, thereby maintaining a stable dispersion state.

According to some embodiments of the invention, the mass ratio of the nanoparticles to the first polymer is greater than 9: 1.

Too high a first polymer content can make it difficult for the nanoparticles to form a continuous phase, losing the unique adsorption and separation characteristics of the nanoparticles themselves for gas separation.

The low or no use of the first polymer can lead to the aggregation and instability of the nano particles in the coating process, and the distribution uniformity is reduced, and in addition, the proper introduction of the high polymer is beneficial to the improvement of the mechanical stability of the nano coating.

According to some embodiments of the present invention, the total mass concentration of the nanoparticles and the first polymer in the casting solution i is 0.5% to 30%.

When the total mass concentration of the nanoparticles and the first polymer is too high, the coating thickness is not easy to control, and when the total mass concentration is too low, the coating process is not easy to control due to too thin solution.

According to some embodiments of the invention, the mass concentration of the second polymer in the casting solution II is 0.1% to 1.0%.

When the mass concentration of the second polymer is too high, the coating thickness is not easy to control, and when the mass concentration of the second polymer is too low, the coating process is not easy to control due to too thin solution.

According to some embodiments of the present invention, the organic solvent i and the organic solvent ii are each independently selected from at least one of alcohol solvents, amine solvents, sulfone solvents, ketone solvents, hydrocarbon solvents, ether solvents, and nitrile solvents.

According to some embodiments of the invention, the alcoholic solvent comprises at least one of methanol and ethanol.

According to some embodiments of the invention, the amine-based solvent comprises at least one of N, N-dimethylformamide and N, N-dimethylacetamide.

According to some embodiments of the invention, the sulfone-based solvent comprises at least one of dimethyl sulfoxide and sulfolane.

According to some embodiments of the invention, the ketone solvent comprises pyrrolidone.

According to some embodiments of the invention, the hydrocarbon solvent comprises at least one of toluene and xylene.

According to some embodiments of the invention, the ethereal solvent comprises tetrahydrofuran.

According to some embodiments of the invention, the nitrile solvent comprises acetonitrile.

According to some embodiments of the invention, the temperature of the primary drying is 50 ℃ to 80 ℃.

According to some embodiments of the invention, the temperature of the re-drying is from 50 ℃ to 150 ℃.

In a third aspect, the invention provides the use of the above carbon dioxide separation membrane in carbon capture and carbon enrichment.

According to at least one embodiment, the following advantages are provided:

the carbon dioxide separation membrane prepared by the invention is of a three-layer structure, and the problem of defects caused by uneven dispersion or agglomeration of the nano particles in the mixed matrix membrane in the related technology is solved by matching the nano particles with the first polymer to form a nano particle composite layer; meanwhile, the problem of selectivity reduction caused by mismatching of polymer components and inorganic nano particle phase interfaces (surface modification is carried out on nano particles, and compatibility is improved) in the mixed matrix membrane in the related technology is solved. The carbon dioxide separation membrane has high selectivity and permeability to carbon dioxide.

The preparation method of the invention realizes effective dispersion of the nano particles, thereby improving the stability of the nano particles in the carbon dioxide separation membrane and further improving the selectivity of the carbon dioxide separation membrane.

Drawings

FIG. 1 is a SEM photograph showing a cross-section of a carbon dioxide separation membrane obtained in example 1 of the present invention.

Reference numerals:

100. a bottom layer; 101. an intermediate layer; 102. a top layer.

Detailed Description

The concept and technical effects of the present invention will be clearly and completely described below in conjunction with the embodiments to fully understand the objects, features and effects of the present invention. It is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments, and those skilled in the art can obtain other embodiments without inventive effort based on the embodiments of the present invention, and all embodiments are within the protection scope of the present invention.

In the description of the present invention, reference to the description of the terms "one embodiment," "some embodiments," "an illustrative embodiment," "an example," "a specific example," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

The preparation method of the caged crown ether adsorption modified graphene in the embodiment of the invention comprises the following steps:

dissolving 18-crown-6 (CAS number: 17455-13-9; Ward chemical Co., Ltd. of Hubei Ke) in water to prepare an 18-crown ether-6 solution with the mass concentration of 0.01-0.1%, and adjusting the pH value of the solution to 2-3 by adopting hydrochloric acid.

Placing graphene in the prepared 18-crown-6 aqueous solution, stirring at a high speed (8000 rmp-10000 rpm) for 0.5-1 h at normal temperature (20-30 ℃), and then stirring at a low speed (500 rmp-700 rpm) for 8-10 h to uniformly disperse and adsorb 18-crown-6 in a saturated manner; and preparing a suspension containing 18-crown-6 and graphene.

And (3) carrying out spray freeze drying on the suspension containing the 18-crown-6 and the graphene at the temperature of-50 to-30 ℃ to prepare the 18-crown-6 modified graphene.

The preparation method of the DL-2-amino-1-butanol adsorption modified ZSM-5 nano molecular sieve in the embodiment of the invention comprises the following steps:

dissolving DL-2-amino-1-butanol in water to prepare a DL-2-amino-1-butanol solution with the mass concentration of 0.01% -0.5%, and adjusting the pH value of the solution to 3-4 by adopting hydrochloric acid.

And (2) placing the ZSM-5 nanoscale molecular sieve in the prepared DL-2-amino-1-butanol aqueous solution, stirring at a high speed (8000 rmp-10000 rpm) for 1-2 h at normal temperature, and then stirring at a low speed (500 rmp-700 rpm) for 4-5 h to ensure that the nanoscale molecular sieve is uniformly dispersed and adsorbs DL-2-amino-1-butanol in a saturated mode.

And finally, carrying out spray freeze drying on the suspension containing the DL-2-amino-1-butanol and the ZSM-5 nano molecular sieve at the temperature of minus 50 to minus 30 ℃ to prepare the DL-2-amino-1-butanol modified ZSM-5 nano molecular sieve.

Specific examples of the present invention are described in detail below.

Example 1

The embodiment is a preparation method of a carbon dioxide separation membrane, which comprises the following steps:

s1, under high-speed shearing (10000 rpm), dispersing 200.0g of caged crown ether modified graphene (D50 is 10 nm) in 790g of N, N-Dimethylformamide (DMF), and stirring for 2h to obtain a caged crown ether modified graphene dispersion liquid;

then adding 10g of polyvinylidene fluoride (solvay, PVDF9009) into the crown ether modified graphene dispersion liquid, stirring and heating to 80 ℃ for dissolving, wherein the dissolving time is 4 hours, and obtaining a cage-shaped crown ether modified graphene/polyvinylidene fluoride blended casting solution; and (3) carrying out vacuum defoaming on the graphene/polyvinylidene fluoride blended casting solution (the defoaming pressure is 50kPa), and cooling to room temperature (about 25 ℃).

S2, uniformly coating the caged crown ether modified graphene/polyvinylidene fluoride blended membrane casting solution prepared in the step S1 on a porous aramid fiber cloth supporting layer (DuPont TYVEK, the aperture is 0.1-3 mu m) by a slit coating method (a metering pump is adopted to inject the membrane casting solution into a slit coating die head for coating), then placing the porous aramid fiber cloth supporting layer in 15 ℃ water for curing and membrane forming, removing an organic solvent, and drying at 80 ℃ to obtain a caged crown ether modified graphene/polyvinylidene fluoride composite layer;

s3, dissolving 10g of polyaryletheramide (molecular weight is 10000-20000 da, provided by YouMo New Material Co., Ltd.) in 990g of tetrahydrofuran at 80 ℃, and obtaining the polyaryletheramide casting solution with mass concentration of 1.0% after vacuum deaeration and cooling.

And then, uniformly coating the polyaramide casting solution on the crown ether modified graphene/polyvinylidene fluoride composite layer prepared in the step S2 by adopting a micro-concave coating technology, drying the coated ultrathin polymer layer at 100 ℃ to remove the solvent, and then further performing desolventizing treatment in vacuum to obtain the carbon dioxide separation membrane.

In the above steps, before slit coating or dimple coating, each solution is subjected to on-line filtration treatment using a precision filter having a filtration precision of 1 μm to 2 μm.

The preparation method of the caged crown ether modified graphene in the embodiment comprises the following steps:

cage-shaped crown ether (18-crown-6) is attached and adsorbed on the surface or between layers of graphene through physical adsorption.

Dissolving 18-crown-6 in water to prepare an 18-crown-6 solution with the mass concentration of 0.01-0.1%, and adjusting the pH value of the solution to 3 by adopting hydrochloric acid.

Adding graphene into an 18-crown-6 aqueous solution, stirring at a high speed (10000 rpm) for 0.5h at normal temperature (about 25 ℃), and then stirring at a low speed (600 rmp) for 8h to uniformly disperse and adsorb 18-crown-6 in a saturated manner; and preparing a suspension containing 18-crown-6 and graphene. The mass concentration ratio of graphene to 18-crown-6 ether in the finally prepared suspension is 10-100;

and (3) carrying out spray freeze drying on the suspension containing the 18-crown-6 and the graphene at the temperature of-50 ℃ to prepare the 18-crown-6 modified graphene.

Example 2

The embodiment is a preparation method of a carbon dioxide separation membrane, which comprises the following steps:

s1, under high-speed shearing (10000 rpm), dispersing 150.0g of caged crown ether modified graphene (D50 is 10 nm) in 842.5gN, N-Dimethylformamide (DMF), and stirring for 2h to prepare a caged crown ether modified graphene dispersion liquid;

then adding 7.5g of polyisophthaloyl metaphenylene diamine (Futai and New materials Co., Ltd.) into the caged crown ether modified graphene dispersion liquid, stirring and heating to 80 ℃ for dissolving for 4h, and obtaining the caged crown ether modified graphene/polyisophthaloyl metaphenylene diamine blended casting liquid. The casting solution was vacuum defoamed (defoaming pressure 60 kPa), and cooled to room temperature (about 25 ℃ C.).

S2, uniformly coating the caged crown ether modified graphene/polyisophthaloyl metaphenylene diamine blend casting solution prepared in the step S1 on a porous aramid fiber cloth (Dupont TYVEK, the aperture is 0.1-3 mu m) supporting layer by adopting a micro-concave coating technology, then placing the porous aramid fiber cloth in water at 15 ℃ for curing to form a film, removing an organic solvent, and drying at 50 ℃ to obtain a caged crown ether modified graphene/polyisophthaloyl metaphenylene diamine composite layer;

s3, under the temperature of 80 ℃, 991.5g of tetrahydrofuran is added with 8.5 g of polyetherimide (tin-free Kaiyun new materials science and technology Co., Ltd.) to obtain a polyetherimide casting solution with the mass concentration of 0.85 percent after vacuum deaeration and cooling;

and (2) uniformly coating the polyetherimide casting solution on the caged crown ether modified graphene/polyisophthaloyl metaphenylene diamine composite layer prepared in the step S2 by adopting a slit coating technology, drying the coated ultrathin polymer layer at 150 ℃ to remove the solvent, and then further performing desolventizing treatment in vacuum to obtain the carbon dioxide separation membrane.

In the above steps, before slit coating or dimple coating, each solution is subjected to on-line filtration treatment by using a precision filter having a filtration precision of 1 to 2 μm.

The preparation method of the caged crown ether modified graphene in the embodiment comprises the following steps:

cage-like crown ether (18-crown-6, CAS number: 17455-13-9; Hubeike Word chemical Co., Ltd.) was adsorbed on the surface or between layers of graphene by physical adsorption.

Dissolving 18-crown-6 in water to prepare an 18-crown-6 solution with the mass concentration of 0.01-0.1%, and adjusting the pH value of the solution to 3 by adopting hydrochloric acid.

Adding graphene into an 18-crown-6 aqueous solution, stirring at a high speed (10000 rpm) for 0.5h at normal temperature (about 25 ℃), and then stirring at a low speed (600 rmp) for 8h to uniformly disperse and adsorb 18-crown-6 in a saturated manner; and preparing a suspension containing 18-crown-6 and graphene. The mass concentration ratio of graphene to 18-crown-6 ether in the finally prepared suspension is 10-100;

and (3) carrying out spray freeze drying on the suspension containing the 18-crown-6 and the graphene at the temperature of-50 ℃ to prepare the 18-crown-6 modified graphene.

Example 3

The embodiment is a preparation method of a carbon dioxide separation membrane, which comprises the following steps:

s1, under high-speed shearing (10000 rpm), dispersing 145.0g of DL-2-amino-1-butanol (CAS number: 96-20-8; Shanghai Hanyu chemical industry) adsorption modified (adsorption equivalent is 4.0 mg/g) ZSM-5 nano molecular sieve (Zhuran environmental protection (Dalian) science and technology Co., Ltd., D50 is 20 nm) in 847.5g of N, N-Dimethylformamide (DMF), and stirring for 2h to prepare DL-2-amino-1-butanol ZSM-5 molecular sieve dispersion liquid;

then adding 7.5g of polyvinylidene fluoride (solvay, PVDF9009) into the DL-2-amino-1-butanol ZSM5 molecular sieve dispersion, stirring and heating to 80 ℃ for dissolving for 4 hours to obtain DL-2-amino-1-butanol ZSM-5 molecular sieve/polyvinylidene fluoride blended casting solution. The casting solution was vacuum defoamed (defoaming pressure 80 kPa), and cooled to room temperature (about 25 ℃ C.).

S2, uniformly coating the DL-2-amino-1-butanol ZSM-5 molecular sieve/polyvinylidene fluoride blended casting solution prepared in the step S1 on a porous aramid fiber cloth (DuPont TYVEK, the aperture is 0.1-3 mu m) supporting layer by adopting a micro-concave coating coupling ultrasonic technology, then placing the porous aramid fiber cloth in 15 ℃ water for curing to form a film, removing an organic solvent, and drying at 50 ℃ to obtain a DL-2-amino-1-butanol ZSM-5 molecular sieve/polyvinylidene fluoride composite layer;

s3, under the temperature of 80 ℃, 991.5g of tetrahydrofuran is added with 8.5 g of polyetherimide (tin-free Kaiyun new materials science and technology Co., Ltd.) to obtain a polyetherimide casting solution with the mass concentration of 0.85 percent after vacuum deaeration and cooling;

and (2) uniformly coating the polyetherimide membrane casting solution on the DL-2-amino-1-butanol ZSM-5 molecular sieve/polyvinylidene fluoride composite layer prepared in the step S2 by adopting a slit coating coupling ultrasonic technology, drying the coated ultrathin polymer layer at 150 ℃ to remove the solvent, and then further performing desolventizing treatment in vacuum to obtain the carbon dioxide separation membrane.

In the above steps, before slit coating or dimple coating, each solution is subjected to on-line filtration treatment using a precision filter having a filtration precision of 1 μm to 2 μm.

In this example, the method for adsorbing and modifying ZSM-5 nano-scale molecular sieve with DL-2-amino-1-butanol comprises the following steps: the method comprises the following steps:

dissolving DL-2-amino-1-butanol in water to prepare DL-2-amino-1-butanol solution with mass concentration of 0.5%, and adjusting pH value of the solution to 3 with hydrochloric acid.

ZSM-5 nano molecular sieve is placed in the prepared DL-2-amino-1-butanol aqueous solution, stirred at high speed (8000 rmp) for 1h at normal temperature (about 25 ℃) and then stirred at low speed (600 rmp) for 4h to ensure that the nano molecular sieve is uniformly dispersed and adsorbs DL-2-amino-1-butanol in a saturated way.

And finally, carrying out spray freeze drying on the suspension containing the DL-2-amino-1-butanol and the ZSM-5 nano molecular sieve at the temperature of-40 ℃ to prepare the DL-2-amino-1-butanol modified ZSM-5 nano molecular sieve.

Comparative example

The comparative example is a method for preparing a carbon dioxide separation membrane, comprising the steps of:

s1, under high-speed shearing, 50.0g of graphene is dispersed in 800g of N, N-Dimethylformamide (DMF), and stirred for 2 h.

And then adding 150g of polyvinylidene fluoride into the graphene dispersion liquid, stirring and heating to 80 ℃ for dissolving, and dissolving for 4 hours to obtain the graphene/polyvinylidene fluoride blended casting solution. And (4) defoaming the casting solution in vacuum, and cooling to room temperature (about 25 ℃) for later use.

S2, uniformly coating the graphene/polyvinylidene fluoride blended membrane casting solution prepared in the step S1 on a porous aramid fiber cloth (DuPont TYVEK, the aperture is 0.1-3 mu m) supporting layer by adopting a slit coating or micro-concave coating technology, and drying at 150 ℃ to remove an organic solvent to obtain a carbon dioxide separation membrane (graphene/polyvinylidene fluoride mixed matrix gas separation membrane).

In the above steps, before slit coating or dimple coating, each solution is subjected to on-line filtration treatment using a precision filter having a filtration precision of 1 μm to 2 μm.

The performance test methods of the embodiments 1-3 and the comparative example are as follows:

the gas membrane process follows a 'dissolution-diffusion' model, and the gas permeability is mainly tested by a constant volume-pressure difference method. The test chamber of the device is divided into a high-pressure chamber and a low-pressure chamber by the sample, the high-pressure chamber is filled with gas to be tested at a certain pressure, and the low-pressure chamber is vacuumized to form a low-pressure environment. During the test, gas permeates into the low-pressure cavity from the high-pressure cavity through the sample under the action of pressure difference, the pressure in the low-pressure cavity is gradually increased, when the permeation of the gas at two sides of the sample reaches a stable state, the increase amount of the pressure in the low-pressure cavity and the permeation time are in a linear relation, and the gas permeation amount of the sample is calculated by measuring the change value of the pressure in the low-pressure cavity in unit time at the moment.

1. Single gas testing method

The gas permeability of the carbon dioxide separation membrane is realized by adopting a constant volume pressure difference methodThe biomass was tested on a gas permeability tester (Changshan blue film mechanical Equipment Co., Ltd.) with a single component of CO₂And N₂Purity of 99.999% and CO₂And N₂The single gas permeability test was carried out at a pressure of 3.5bar and a temperature of 30 ℃. CO 2₂And N₂The gas permeability is calculated according to the following formula.

。

Wherein P is_APermeability of the membrane, V_pIs the osmotic flow (cm)³(STP)/S), t is the thickness (cm) of the film, A_mIs the area (cm) of the membrane²），P_hAnd P_lThe pressures on the gas inlet side and the gas permeation side, respectively.

2、CO₂And N₂Ideal selectivity calculation

CO₂And N₂The ideal selectivity calculation is based on the following equation:

。

wherein alpha is CO₂And N₂Ideal selectivity, P_CO2And P_N2Is a membrane to CO₂And N₂Permeability of (2).

3. Gas permeability tester

The using method comprises the following steps:

1. the membrane to be tested was mounted on the membrane cell.

2. Closing all valves, opening a downstream valve, observing the pressure reading change (gradual reduction) of downstream pressure software (TGEXEpressl), closing the downstream valve and opening an upstream valve after the vacuum pumping time is more than 4h and the reading tends to be stable, (the time is less than 20 s; and the phenomenon of upstream air leakage caused by overlong time is prevented). And closing the upstream valve, opening the downstream valve, and starting the test after the reading is stable.

3. Test procedure

a) And closing the downstream throttle.

b) And selecting a file saving path.

c) And opening an upstream air inlet valve to adjust the pressure.

d) The can was opened to the upstream valve and the computer clicked "ok" to begin the test.

e) And (4) closing the upstream air inlet valve after testing, and exhausting the upstream air. And (3) repeating the step (2), but shortening the downstream time by more than half an hour.

Note: the test time recommendation is greater than 10 times time-lag.

The performance test results of the carbon dioxide separation membranes prepared in the embodiments 1-2 and the comparative example are as follows:

comparative example: carbon dioxide permeability 1437Barrer, CO₂/N₂The coefficient was chosen to be 25.2.

Example 1: permeability of carbon dioxide 4021Barrer, CO₂/N₂The coefficient was chosen to be 47.7.

Example 2: carbon dioxide permeability 3407 Barrer; CO 2₂/N₂A factor of 93.2 was chosen.

Example 3: carbon dioxide permeability 3894 Barrer; CO 2₂/N₂The factor 91.7 was chosen.

The cross-sectional SEM image of the carbon dioxide separation membrane prepared in example 1 of the invention is shown in FIG. 1, and is known from FIG. 1; the carbon dioxide separation membrane prepared in the embodiment 1 of the invention has a three-layer structure (a bottom layer 100, a middle layer 101, and a top layer 102 above the dotted line); wherein the upper middle layer (the caged crown ether modified graphene/polyvinylidene fluoride composite layer) is slightly compact relative to the lower half part, namely the middle interface structure in the figure 1 is formed.

In the embodiment 1 of the invention, the thickness of each layer is respectively a porous aramid fiber cloth support layer (70 μm), a graphene/polyvinylidene fluoride composite layer (18.7 μm) and a polyaryletheramide layer (3.4 μm).

In embodiment 2 of the invention, the thickness of each layer is respectively a porous aramid fiber cloth support layer (70 μm), a caged crown ether modified graphene/polyisophthaloyl metaphenylene diamine composite layer (15 μm) and a polyetherimide layer (3.5 μm).

In the embodiment 3 of the invention, the thicknesses of each layer are respectively a porous aramid fiber cloth support layer (70 μm), a DL-2-amino-1-butanol ZSM-5 molecular sieve/polyvinylidene fluoride composite layer (15 μm) and a polyetherimide layer (3.5 μm).

The thicknesses of the layers in the comparative example are respectively a porous aramid fiber cloth supporting layer (70 mu m) and a graphene/polyvinylidene fluoride composite layer (18.7 mu m).

In conclusion, the carbon dioxide separation membrane provided by the invention solves the problem that the structure of the mixed matrix membrane in the related art cannot fully embody the performance advantages by adopting a multilayer structure; the defect problem caused by uneven dispersion or agglomeration of the nano particles in the mixed matrix membrane in the related technology is also solved; the problem of selectivity reduction caused by mismatching of polymer components and inorganic nano particle phase interfaces in the mixed matrix membrane in the related technology is further solved; meanwhile, the problem of low permeability caused by higher polymer component of the membrane body or thicker membrane body in the mixed matrix membrane in the related technology is solved; the preparation method solves the problem of limited large-scale preparation caused by immature nanoparticle dispersion process in the mixed matrix membrane in the related technology.

While the embodiments of the present invention have been described in detail with reference to the specific embodiments, the present invention is not limited to the embodiments, and various changes can be made without departing from the spirit of the present invention within the knowledge of those skilled in the art. Furthermore, the embodiments of the present invention and the features of the embodiments may be combined with each other without conflict.