A hydrogen separation membrane and preparation method thereof

Abstract

The present invention discloses a hydrogen separation membrane and a preparation method thereof, and relates to the technical field of hydrogen separation materials, so as to solve the problem that the gas selectivity and permeability of organic polymer membrane materials are poor when preparing high-purity hydrogen in the prior art. The hydrogen separation membrane comprises: the hydrogen separation membrane comprises a carbon-based fiber membrane, the skeleton of the carbon-based fiber membrane is a porous nano-net structure, and the porous nano-net structure is formed by a porous material. The hydrogen separation membrane and the preparation method provided by the present invention are used to improve the gas selectivity and permeability of the hydrogen separation membrane.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrogen separation materials, and in particular to a hydrogen separation membrane and a preparation method thereof. Background Art

[0002] Hydrogen is an environmentally friendly and clean energy source, an important industrial raw material and clean fuel. Since industrially produced hydrogen usually contains a lot of harmful impurities, it cannot be used directly and needs to be separated. The membrane separation method has a simple structure, high conversion efficiency, low investment cost and is environmentally friendly. It has broad application prospects in the field of hydrogen separation. The performance of the hydrogen separation membrane is the decisive factor affecting the efficiency of the hydrogen separation process.

[0003] At present, organic polymer membrane materials are generally used for hydrogen separation. However, when preparing high-purity hydrogen, the screening performance and permeability of organic polymer membrane materials cannot meet the ideal requirements. Summary of the invention

[0004] The object of the present invention is to provide a hydrogen separation membrane and a preparation method thereof, which realizes high gas selectivity and high permeability of the hydrogen separation membrane and can separate high-purity hydrogen.

[0005] In a first aspect, the present invention provides a hydrogen separation membrane, which includes a carbon-based fiber membrane, wherein the skeleton of the carbon-based fiber membrane is a porous nano-network structure, and the porous nano-network structure is formed of a porous material.

[0006] Compared with the prior art, the hydrogen separation membrane provided by the present invention has the following advantages:

[0007] The hydrogen separation membrane provided by the present invention comprises a carbon-based fiber membrane, the skeleton of the carbon-based fiber membrane is a porous nano-mesh structure, and the porous nano-mesh structure is formed by a porous material. At the same time, the carbon fibers contained in the carbon-based fiber membrane are interlaced and connected with each other to form a porous structure that is convenient for ion and electron transmission. In other words, the porous mesh structure of the carbon-based fiber membrane can make the hydrogen separation membrane have a large number of pores. When hydrogen separation is performed, hydrogen will be permeated by the carbon-based fiber membrane with a porous mesh structure, and a large number of pores can greatly increase the permeability of hydrogen, thereby achieving high gas selectivity of the hydrogen separation membrane. Moreover, the carbon-based fiber membrane also has excellent mechanical flexibility, good chemical stability and environmental friendliness, which can extend the service life of the hydrogen separation membrane and improve the scope of application of the hydrogen separation membrane.

[0008] It can be seen from the above that the hydrogen separation membrane provided by the present invention can improve the gas selectivity of hydrogen and extend the service life of the hydrogen separation membrane.

[0009] In a second aspect, the present invention further provides a method for preparing a hydrogen separation membrane, comprising:

[0010] The casting solution is made into a hollow fiber membrane precursor through a spinning process;

[0011] The hollow fiber membrane precursor is heat-treated to form a hydrogen separation membrane; wherein the casting solution contains a polymer, an organic solvent, nanocellulose and a porous material.

[0012] Compared with the prior art, the beneficial effects of the method for preparing the hydrogen separation membrane provided by the present invention are the same as the beneficial effects of the hydrogen separation membrane of the first aspect, and will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0014] Figure 1 This is a flow chart of the preparation of a hydrogen separation membrane according to an embodiment of the present invention;

[0015] Figure 2 The present invention is a flow chart of the preparation of a homogeneous casting solution. DETAILED DESCRIPTION

[0016] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0017] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined. The meaning of "several" is one or more, unless otherwise clearly and specifically defined.

[0018] Hydrogen has been recognized as an environmentally friendly and clean energy source, an important industrial raw material and clean fuel. As an important component of the future energy system, hydrogen energy will be widely used in industries that are difficult to decarbonize, such as industry, transportation, building heating, and other emerging industries. The substantial increase in demand for hydrogen energy has put forward direct requirements on the efficiency, cost, and quality of hydrogen production. Since industrially produced hydrogen usually contains more harmful impurity gases and cannot be directly used, hydrogen separation has important economic and social value. The membrane separation method has a simple structure, efficient conversion, low investment cost, and is environmentally friendly. It has broad application prospects in the field of hydrogen separation. The performance of the hydrogen separation membrane is the decisive factor affecting the efficiency of the hydrogen separation process.

[0019] The hydrogen separation membrane uses the principle of "molecular sieve". There are homogeneous pores on the hydrogen separation membrane that only allow hydrogen molecules to pass through. Molecules larger than this pore cannot pass through, thereby separating hydrogen and substances other than hydrogen. At present, organic polymer membrane materials are generally used for hydrogen separation. However, when preparing high-purity hydrogen, the screening performance and permeability of organic polymer membrane materials cannot meet the ideal requirements.

[0020] In view of the above problems, an embodiment of the present invention provides a hydrogen separation membrane to improve the gas selectivity and permeability of the hydrogen separation membrane, so as to separate high-purity hydrogen.

[0021] The hydrogen separation membrane provided by the embodiment of the present invention includes a carbon-based fiber membrane, the skeleton of the carbon-based fiber membrane is a porous nano-network structure, and the porous nano-network structure is formed by a porous material. It should be understood that the carbon-based fiber membrane includes a hollow fiber-shaped carbon-based fiber membrane and / or a flat carbon-based fiber membrane, which is a homogeneous membrane and is a continuous porous nano-network structure as a whole.

[0022] The hydrogen separation membrane provided by the present invention comprises a carbon-based fiber membrane, the skeleton of the carbon-based fiber membrane is a porous nano-mesh structure, and the porous nano-mesh structure is formed by a porous material. At the same time, the carbon fibers contained in the carbon-based fiber membrane are interlaced and connected with each other to form a porous structure that is convenient for ion and electron transmission. In other words, the porous mesh structure of the carbon-based fiber membrane can make the hydrogen separation membrane have a large number of pores. When hydrogen separation is performed, hydrogen will be permeated using the carbon-based fiber membrane with a porous mesh structure, and a large number of pores can greatly increase the gas selectivity of hydrogen, thereby achieving high permeability of the hydrogen separation membrane. Moreover, the carbon-based fiber membrane also has excellent mechanical flexibility, good chemical stability and environmental friendliness, which can extend the service life of the hydrogen separation membrane and improve the scope of application of the hydrogen separation membrane.

[0023] In an optional manner, the porous nano-mesh structure of the embodiment of the present invention contains micropores with a pore size of 0.3nm~0.6nm. The micropores contained in the porous network structure of the carbon-based fiber membrane of the embodiment of the present invention near the cortex (i.e., the membrane surface) are relatively dense. Therefore, when hydrogen separation is performed, the pore size can be between the kinetic diameters of the key components to be separated (such as hydrogen and nitrogen separation), and the hydrogen with a smaller kinetic diameter (0.289nm) passes through the pores, while the nitrogen with a relatively larger kinetic diameter (0.364nm) is not easy to pass through the pores, thereby achieving the purpose of H2 / N2 gas separation.

[0024] The hollow fiber carbon-based fiber membrane of the embodiment of the present invention is a fiber-like membrane with a hollow inner cavity, which has a self-supporting effect. When hydrogen separation is performed, the fiber-like hollow fiber carbon membrane with a hollow inner cavity has good selective permeability, which greatly improves the gas selectivity of hydrogen.

[0025] Exemplarily, the porous material of the embodiment of the present invention includes a metal sintered body and / or a zeolite molecular sieve, wherein the metal sintered body includes at least one of a nano nickel powder light sintered body, a nano silver powder light sintered body and a nano aluminum powder light sintered body, preferably a nano nickel powder light sintered body, the metal sintered body has a hydrogen adsorption function, and the specific surface area of ​​the metal sintered body is 20m 2 / g~27m 2 / g, the particle size of the metal sintered body is 10nm~20nm, and the pore size of the zeolite molecular sieve is less than 3Å. It should be understood that the metal sintered body is a light sintered body that can form a sponge after sintering at a lower temperature. The sintering process of the metal sintered body is a gradual process. As the sintering time increases, the metal sintered body gradually shrinks from a disordered nano-powder state to form an ordered light sintered structure. When the porous material includes a metal sintered body, the particle size of the metal sintered body is 10nm~20nm, and the specific surface area of ​​the metal sintered body is 20m 2 / g~27m 2 / g, the metal sintered body can generate a microporous filter as a storage material for adsorbing hydrogen, etc., which improves the adsorption capacity of hydrogen. When the metal sintered body is a nano nickel powder light sintered body, the nano nickel powder light sintered body has the characteristics of high selective adsorption of hydrogen, and the nano nickel powder particles have a large specific surface area, high surface reaction activity, many surface active centers, high catalytic efficiency, and strong adsorption capacity, which can make the hydrogen separation membrane have good adsorption.

[0026] On this basis, the above-mentioned zeolite molecular sieves include Å-type molecular sieves, X-type molecular sieves, Y-type molecular sieves, M-type molecular sieves and ZSM-type molecular sieves. When the above-mentioned zeolite molecular sieve is an Å-type molecular sieve, the Å-type molecular sieve may include a 3Å molecular sieve, a 4Å molecular sieve and a 5Å molecular sieve. Since zeolite molecular sieves are a type of hydrated crystalline aluminosilicates, they are typical microporous inorganic substances and have excellent thermal stability and chemical stability. There are many holes and channels of uniform size inside the zeolite molecular sieve lattice, and the volume of the holes and channels may account for more than 50% of the volume of the zeolite molecular sieve crystals. These holes and channels have precise and fixed diameters under certain physical and chemical conditions. When the pore size of the above-mentioned zeolite molecular sieve is less than 3Å, the zeolite molecular sieve can be used as an adsorbent to selectively adsorb hydrogen, making the hydrogen permeation rate faster. At the same time, because there are strong Coulomb fields and polar effects inside the crystal cells of zeolite molecular sieves, and the crystal cells are not wide enough to allow fluid molecules to avoid the effects of the fields in the lattice, zeolite as an adsorbent not only has the function of screening molecules, but also has higher adsorption capacity than other types of adsorbents even at higher temperatures and lower adsorbate partial pressures.

[0027] That is to say, in terms of the pore structure design for gas separation, a porous molecular skeleton with affinity and adsorption capacity for hydrogen molecules is constructed. By introducing a lightly sintered body of ultrafine particles, the role of a microporous filter can be played to adsorb hydrogen. At the same time, the added zeolite microporous material can also be used as a hydrogen adsorbent, further improving the hydrogen permeation efficiency.

[0028] In one achievable approach, Figure 1 The preparation flow chart of the hydrogen separation membrane provided by the embodiment of the present invention is shown as follows: Figure 1 As shown, the present invention also provides a method for preparing the hydrogen separation membrane, comprising:

[0029] Step 101: Prepare a hollow fiber membrane precursor from a casting solution by a spinning process, wherein the casting solution is a homogeneous casting solution, and the casting solution contains a polymer, an organic solvent, nanocellulose and a porous material.

[0030] Exemplarily, the embodiment of the present invention adopts a hollow fiber membrane spinning device to prepare a fiber membrane precursor. First, the prepared casting solution is allowed to stand for degassing for 6-10 hours, and then nitrogen is introduced, extruded through a spinneret under a certain pressure, and at a certain draft rate, first cooled by air, and then cooled and formed in warm water in a coagulation bath to obtain a hollow fiber membrane precursor. Among them, the pressure range is 0.02MPa~0.06MPa, the spinning rate is 1m / min~5m / min, the air segment spacing of the hollow fiber membrane spinning device is 20cm~30cm, and the core liquid is triethylene glycol or propylene glycol. When the casting solution passes through the air segment, the solvent will volatilize due to the temperature difference, forming a small amount of pores. At the same time, during the solidification process of the membrane filaments extruded from the spinneret, the polymer solution contained in the casting liquid becomes thermodynamically unstable due to the double diffusion of the solvent and the non-solvent, and then solid-liquid phase separation occurs. The polymer-rich phase solidifies to form the main body of the membrane, while the polymer-poor phase forms the so-called pore structure, so that the outer surface of the formed fiber membrane is a dense layer, and the inner mesh pore structure serves as a support layer. Therefore, a continuous porous mesh structure is formed, which is conducive to the permeation of hydrogen and improves the hydrogen permeability.

[0031] In an optional manner, when the above-mentioned porous material includes a metal sintered body and a zeolite molecular sieve, in the above-mentioned casting liquid, the mass fraction of the polymer is 10 weight parts to 15 weight parts, the mass fraction of the organic solvent is 70 weight parts to 90 weight parts, the mass fraction of nanocellulose is 1 weight part to 5 weight parts, the mass fraction of the metal sintered body is 0.5 weight parts to 3 weight parts, and the mass fraction of the zeolite molecular sieve is 0.1 weight part to 1 weight part.

[0032] Step 102: heat-treating the hollow fiber membrane precursor into a hydrogen separation membrane.

[0033] Exemplarily, the above-mentioned hollow fiber membrane precursor is heat-treated under a vacuum environment, and a hollow fiber membrane, i.e., a hydrogen separation membrane, is obtained after being kept warm for a period of time. Wherein, the heat treatment temperature is 600°C~1000°C, and the insulation time is 2h~5h. The skeleton of the hydrogen separation membrane is a nanoporous structure, which can efficiently adsorb hydrogen, so that the permeability and selectivity of hydrogen are high. At the same time, the hollow fiber hydrogen separation membrane has high mechanical strength and can be used under high temperature and high pressure environments. The polymer undergoes molecular chain breakage during the carbonization process, and the generated small molecules escape in the form of gas, and the channels when the gas escapes form a porous structure. The larger pores in the membrane are connected by smaller pores, thereby giving the membrane better screening performance and permeability.

[0034] In an alternative approach, Figure 2 The preparation flow chart of the homogeneous casting solution provided in the embodiment of the present invention is shown. Figure 2 As shown, the preparation method of the homogeneous casting solution provided in the embodiment of the present invention includes:

[0035] Step 201: Mix and stir the polymer, organic solvent and nanocellulose at 100° C. to obtain a premix.

[0036] For example, polymer, organic solvent and nanocellulose are added to a stirring tank in a certain proportion, mixed and stirred evenly at a temperature of 100°C to 180°C to obtain a premix. In the process of obtaining a premix by introducing nanocellulose in the embodiment of the present invention, the fiber bundle nanofibers undergo molecular pyrolysis under a high temperature environment to form pores, thereby forming a highly selective nanoscale pore structure. At the same time, nanocellulose has the effect of weakening local stress at the interface, and can also prevent cracks and damage from expanding, thereby playing a reinforcing role. Among them, the particle size of nanocellulose is 3nm~4nm.

[0037] Step 202: Mix and stir the premix with the porous material to form a homogeneous casting solution.

[0038] For example, the premix is ​​mixed with a porous material to form a homogeneous casting solution. It should be understood that the polymer includes polyacrylonitrile and / or polyimide, the organic solvent includes at least one of N-methylpyrrolidone, N,N-dimethylacetamide and N,N-dimethylformamide, and the nanocellulose can be cellulose nanofibers. Among them, nanocellulose has a large specific surface area, excellent mechanical flexibility, good chemical stability and environmental friendliness, and the fibers are interlaced with each other, so that it is easy to form a porous structure that is convenient for ion and electron transmission, which can make the hydrogen separation membrane have a large number of pores, thereby achieving high permeability of the hydrogen separation membrane. At the same time, the nanocellulose-based functional material can be composited with an electroactive material through high-temperature carbonization to obtain a hydrogen separation membrane with a finer nanostructure and excellent electrochemical properties.

[0039] The preparation method of the hydrogen separation membrane provided by the present invention, on the one hand, constructs a highly selective nanoscale pore structure by introducing nanocellulose. On the other hand, by introducing ultrafine metal sintered bodies and zeolite microporous materials to improve the adsorption capacity of hydrogen, the permeability of hydrogen is effectively enhanced. Finally, the polymer precursor is carbonized or pyrolyzed by high-temperature carbonization treatment to prepare a new inorganic hydrogen separation membrane. The polymer undergoes molecular chain breakage during the carbonization process, and the generated small molecules escape in the form of gas, and the channel during the gas escape forms a porous structure. Two adjacent pores with smaller pore sizes in the membrane pass through the micropores with larger pore sizes and are connected, so that the hydrogen separation membrane can pass through the micropores with larger pore sizes while also passing through the pores with smaller pore sizes, thereby improving the screening performance of the hydrogen separation membrane, so that the purity of the separated hydrogen is improved. At the same time, the preparation method is simple and easy to operate, and is easy to industrialize and produce.

[0040] In order to verify the effect of the hydrogen separation membrane provided by the embodiment of the present invention, the embodiment of the present invention is demonstrated by comparing the embodiment with a comparative example.

[0041] Embodiment 1

[0042] The hydrogen separation membrane provided by the embodiment of the present invention comprises, by mass percentage, a carbon fiber membrane and a porous skeleton dispersed in the carbon fiber membrane.

[0043] The method for preparing a hydrogen separation membrane provided in the first embodiment of the present invention comprises the following steps:

[0044] The first step is the preparation of a homogeneous casting solution: 12 parts by weight of polyacrylonitrile, 84.5 parts by weight of NMP, and 2 parts by weight of cellulose nanofibers are added to a stirring tank in sequence, mixed and stirred evenly at 130°C, and then 1 part by weight of a lightly sintered nano-nickel powder and 0.5 parts by weight of a 5Å molecular sieve are added, and stirring is continued to form a homogeneous casting solution (solid content 15.5%).

[0045] The second step is the preparation of hydrogen separation membrane precursor: using hollow fiber membrane spinning equipment, first let the casting liquid prepared in the first step stand and degas for 8 hours, then introduce nitrogen, extrude it through the spinneret at a pressure of 0.03MPa, and at a drawing rate of 2m / min, first cool it with an air gap of 25cm, and then cool it in a coagulation bath to obtain a hydrogen separation membrane precursor. The core liquid uses triethylene glycol and the coagulation bath is room temperature water.

[0046] The third step is to prepare the hydrogen separation membrane: the hydrogen separation membrane precursor prepared in the second step is subjected to high-temperature heat treatment at 800°C in a vacuum environment and kept warm for 3 hours to obtain a hollow fiber hydrogen separation membrane.

[0047] Embodiment 2

[0048] The hydrogen separation membrane provided by the embodiment of the present invention comprises, by mass percentage, a carbon fiber membrane and a porous skeleton dispersed in the carbon fiber membrane.

[0049] The method for preparing a hydrogen separation membrane provided in the second embodiment of the present invention comprises the following steps:

[0050] The first step is the preparation of a homogeneous casting solution: 13 parts by weight of polyacrylonitrile, 80 parts by weight of NMP, and 4 parts by weight of cellulose nanofibers are added to a stirring tank in sequence, mixed and stirred evenly at 160°C, and then 2 parts by weight of a lightly sintered nano-nickel powder and 1 part by weight of a 5Å molecular sieve are added, and stirring is continued to form a homogeneous casting solution (solid content 20%).

[0051] The second step is the preparation of hydrogen separation membrane precursor: using hollow fiber membrane spinning equipment, first let the casting liquid prepared in the first step stand and degas for 10 hours, then introduce nitrogen, extrude it through the spinneret at a pressure of 0.03MPa, and at a drawing rate of 2.5m / min, first cool it with an air gap of 20cm, and then cool it in a coagulation bath to obtain a hydrogen separation membrane precursor. The core liquid uses triethylene glycol and the coagulation bath is room temperature water.

[0052] The third step is to prepare the hydrogen separation membrane: the hydrogen separation membrane precursor prepared in the second step is subjected to high-temperature heat treatment at 950°C in a vacuum environment and kept warm for 3 hours to obtain a hollow fiber hydrogen separation membrane.

[0053] Embodiment 3

[0054] The hydrogen separation membrane provided by the embodiment of the present invention comprises, by mass percentage, a carbon fiber membrane and a porous skeleton dispersed in the carbon fiber membrane.

[0055] The method for preparing a hydrogen separation membrane provided in the third embodiment of the present invention comprises the following steps:

[0056] The first step is the preparation of a homogeneous casting solution: 12 parts by weight of polyacrylonitrile, 83 parts by weight of NMP, and 3 parts by weight of cellulose nanofibers are added to a stirring tank in sequence, mixed and stirred evenly at 140°C, and then 1.5 parts by weight of a lightly sintered nano-nickel powder and 0.5 parts by weight of a 5Å molecular sieve are added, and stirring is continued to form a homogeneous casting solution (solid content 17%).

[0057] The second step is the preparation of hydrogen separation membrane precursor: using hollow fiber membrane spinning equipment, first let the casting liquid prepared in the first step stand and degas for 8 hours, then introduce nitrogen, extrude it through the spinneret at a pressure of 0.05MPa, and at a drawing rate of 2m / min, first cool it with an air gap of 25cm, and then cool it in a coagulation bath to obtain a hydrogen separation membrane precursor. The core liquid uses triethylene glycol and the coagulation bath is room temperature water.

[0058] The third step is to prepare the hydrogen separation membrane: the hydrogen separation membrane precursor prepared in the second step is subjected to high-temperature heat treatment at 900°C in a vacuum environment and kept warm for 3 hours to obtain a hollow fiber hydrogen separation membrane.

[0059] Embodiment 4

[0060] The hydrogen separation membrane provided by the embodiment of the present invention comprises, by mass percentage, a carbon fiber membrane and a porous skeleton dispersed in the carbon fiber membrane.

[0061] The method for preparing a hydrogen separation membrane provided in the fourth embodiment of the present invention comprises the following steps:

[0062] The first step is the preparation of a homogeneous casting solution: 10 parts by weight of polyimide, 70 parts by weight of NMP, and 1 part by weight of cellulose nanofibers are added to a stirring tank in sequence, mixed and stirred evenly at 100°C, and then 0.5 parts by weight of a lightly sintered nano-nickel powder and 3 parts by weight of a 5Å molecular sieve are added, and stirring is continued to form a homogeneous casting solution (solid content 17.16%).

[0063] The second step is the preparation of hydrogen separation membrane precursor: using hollow fiber membrane spinning equipment, first let the casting liquid prepared in the first step stand and degas for 6 hours, then introduce nitrogen, extrude it through the spinneret at a pressure of 0.02MPa, and at a drawing rate of 1m / min, first cool it with an air gap of 20cm, and then cool it in a coagulation bath to obtain a hydrogen separation membrane precursor. The core liquid uses triethylene glycol and the coagulation bath is room temperature water.

[0064] The third step is to prepare the hydrogen separation membrane: the hydrogen separation membrane precursor prepared in the second step is subjected to high-temperature heat treatment in a vacuum environment at a temperature of 600°C and kept warm for 2 hours to obtain a hollow fiber hydrogen separation membrane.

[0065] Embodiment 5

[0066] The hydrogen separation membrane provided by the embodiment of the present invention comprises, by mass percentage, a carbon fiber membrane and a porous skeleton dispersed in the carbon fiber membrane.

[0067] The method for preparing a hydrogen separation membrane provided in the fifth embodiment of the present invention comprises the following steps:

[0068] The first step is the preparation of a homogeneous casting solution: 15 parts by weight of polyimide, 90 parts by weight of N,N-dimethylacetamide, and 5 parts by weight of cellulose nanofibers are added to a stirring tank in sequence, mixed and stirred evenly at 180°C, and then 3 parts by weight of a lightly sintered nano-nickel powder and 1 part by weight of a 5Å molecular sieve are added, and stirring is continued to form a homogeneous casting solution (solid content 21.05%).

[0069] The second step is the preparation of hydrogen separation membrane precursor: using hollow fiber membrane spinning equipment, first let the casting liquid prepared in the first step stand and degas for 10 hours, then introduce nitrogen, extrude it through the spinneret at a pressure of 0.06MPa, and at a drawing rate of 5m / min, first cool it with an air gap of 30cm, and then cool it in a coagulation bath to obtain a hydrogen separation membrane precursor. The core liquid uses triethylene glycol and the coagulation bath is room temperature water.

[0070] The third step is to prepare the hydrogen separation membrane: the hydrogen separation membrane precursor prepared in the second step is subjected to high-temperature heat treatment in a vacuum environment at a temperature of 1000°C and kept warm for 5 hours to obtain a hollow fiber hydrogen separation membrane.

[0071] Embodiment 6

[0072] The hydrogen separation membrane provided by the embodiment of the present invention comprises, by mass percentage, a carbon fiber membrane and a porous skeleton dispersed in the carbon fiber membrane.

[0073] The method for preparing a hydrogen separation membrane provided in Example 6 of the present invention comprises the following steps:

[0074] The first step is the preparation of a homogeneous casting liquid: 12 parts by weight of polyacrylonitrile, 85 parts by weight of N,N-dimethylformamide, and 3 parts by weight of cellulose nanofibers are added to a stirring tank in sequence, mixed and stirred evenly at 150°C, and then 3 parts by weight of a lightly sintered nano-nickel powder and 0.8 parts by weight of a 5Å molecular sieve are added, and stirring is continued to form a homogeneous casting liquid (solid content 18.11%).

[0075] The second step is the preparation of hydrogen separation membrane precursor: using hollow fiber membrane spinning equipment, first let the casting liquid prepared in the first step stand for degassing for 9 hours, then introduce nitrogen, extrude it through the spinneret at a pressure of 0.04MPa, and at a drawing rate of 4m / min, first cool it with an air gap of 22cm, and then cool it in a coagulation bath to obtain a hydrogen separation membrane precursor. The core liquid uses triethylene glycol and the coagulation bath is room temperature water.

[0076] The third step is to prepare the hydrogen separation membrane: the hydrogen separation membrane precursor prepared in the second step is subjected to high-temperature heat treatment at 700°C in a vacuum environment and kept warm for 4 hours to obtain a hollow fiber hydrogen separation membrane.

[0077] Comparative Example 1

[0078] The hydrogen separation membrane provided in Comparative Example 1 of the present invention does not contain the nanocellulose of the present application.

[0079] The method for preparing the hydrogen separation membrane provided in Comparative Example 1 of the present invention comprises the following steps:

[0080] The first step is the preparation of a homogeneous casting liquid: 15 parts by weight of polyacrylonitrile and 82 parts by weight of NMP are added to a stirring tank in sequence, mixed and stirred evenly at 160°C, and then 3 parts by weight of a lightly sintered nano-nickel powder and 1 part by weight of a 5Å molecular sieve are added, and stirring is continued to form a homogeneous casting liquid (solid content 18.81%).

[0081] The second step is the preparation of hydrogen separation membrane precursor: using hollow fiber membrane spinning equipment, first let the casting liquid prepared in the first step stand and degas for 8 hours, then introduce nitrogen, extrude it through the spinneret at a pressure of 0.03MPa, and at a drawing rate of 2m / min, first cool it with an air gap of 25cm, and then cool it in a coagulation bath to obtain a hydrogen separation membrane precursor. The core liquid uses triethylene glycol and the coagulation bath is room temperature water.

[0082] The third step is to prepare the hydrogen separation membrane: the hydrogen separation membrane precursor prepared in the second step is subjected to high-temperature heat treatment in a vacuum environment at a temperature of 800°C and kept warm for 3 hours to obtain the hydrogen separation membrane.

[0083] Comparative Example 2

[0084] The hydrogen separation membrane provided in Comparative Example 2 of the present invention does not contain the porous material of the present application.

[0085] The preparation method of the hydrogen separation membrane provided in Comparative Example 2 of the present invention comprises the following steps:

[0086] The first step is to prepare a homogeneous casting solution: 13 parts by weight of polyacrylonitrile, 83 parts by weight of DMAC, and 4 parts by weight of cellulose nanofibers are added to a stirring tank in sequence, and mixed and stirred evenly at a temperature of 150°C to form a homogeneous casting solution (solid content 17%).

[0087] The second step is the preparation of hydrogen separation membrane precursor: using hollow fiber membrane spinning equipment, first let the casting liquid prepared in the first step stand and degas for 8 hours, then introduce nitrogen, extrude it through the spinneret at a pressure of 0.03MPa, and at a drawing rate of 2m / min, first cool it with an air gap of 25cm, and then cool it in a coagulation bath to obtain a hydrogen separation membrane precursor. The core liquid uses triethylene glycol and the coagulation bath is room temperature water.

[0088] The third step is to prepare the hydrogen separation membrane: the hydrogen separation membrane precursor prepared in the second step is subjected to high-temperature heat treatment in a vacuum environment at a temperature of 800°C and kept warm for 3 hours to obtain the hydrogen separation membrane.

[0089] The present invention performs performance tests on the hydrogen separation membranes of Examples 1 to 3, Comparative Examples 1 and 2. The test method is as follows:

[0090] Hydrogen permeation flux: Please refer to the test method in "Preparation and Gas Separation Performance of ZIF-8 and ZIF-67 Metal-Organic Framework Membranes", unit: 10-8mol·m-2·s-1·Pa-1.

[0091] H 2 / N 2Separation coefficient: Please refer to the test method in "Preparation and Gas Separation Performance Study of ZIF-8 and ZIF-67 Metal-Organic Framework Membranes" for details.

[0092] Pore ​​size distribution: This test adopts Ar adsorption method, unit: nm.

[0093] Mechanical strength: A universal tensile testing machine was used to test the tensile strength of the hollow fiber membrane. Unit: MPa.

[0094] The test results of the hydrogen separation membranes provided in Examples 1 to 3 of the present invention, Comparative Examples 1 and 2 are as follows:

[0095]

[0096] As can be seen from the above table, in Examples 1 to 3, a casting solution is prepared using a polymer, an organic solvent, nanocellulose and a porous material, and then the casting solution is made into a fiber membrane precursor through a spinning process to prepare a hydrogen separation membrane. The difference between Comparative Example 1 and the Example is that the Comparative Example does not add nanocellulose, and the difference between Comparative Example 2 and the Example is that the Comparative Example does not add a porous material. The hydrogen permeation flux of the hydrogen separation membrane prepared in Examples 1 to 3 is much greater than that of Comparative Example 1 and Comparative Example 2, H 2 / N 2 The separation coefficient and mechanical strength are also greater than those of Comparative Example 1 and Comparative Example 2. It can be seen that the hydrogen separation membrane prepared by using the raw materials and process of the embodiment of the present invention not only has good permeability, but also has good hydrogen screening performance, and has high mechanical strength, so that high-purity hydrogen can be separated.

[0097] The above is only a specific embodiment of the present invention. Obviously, various modifications and combinations can be made without departing from the spirit and scope of the present invention. Accordingly, this specification and the drawings are only exemplary illustrations of the present invention as defined by the attached claims, and are deemed to have covered any and all modifications, changes, combinations or equivalents within the scope of the present invention. Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is intended to include these changes and variations. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be based on the scope of protection of the claims.

Claims

1. A method for preparing a hydrogen separation membrane, characterized in that: include: The homogeneous membrane casting solution is made into a hollow fiber membrane precursor through a spinning process; The hollow fiber membrane precursor is heat-treated to form a hydrogen separation membrane; wherein the casting solution contains a polymer, an organic solvent, nanocellulose and a porous material; the particle size of the nanocellulose is 3nm~4nm, and the porous material includes a metal sinter and / or a zeolite molecular sieve. When the porous material includes a metal sinter and a zeolite molecular sieve, in the casting solution, the mass fraction of the polymer is 10 parts by weight to 15 parts by weight, the mass fraction of the organic solvent is 70 parts by weight to 90 parts by weight, the mass fraction of the nanocellulose is 1 part by weight to 5 parts by weight, the mass fraction of the metal sinter is 0.5 parts by weight to 3 parts by weight, and the mass fraction of the zeolite molecular sieve is 0.1 parts by weight to 1 part by weight; The hydrogen separation membrane comprises a carbon-based fiber membrane, the skeleton of the carbon-based fiber membrane is a porous nano-network structure, the porous nano-network structure is formed by a porous material, and the pore size of the micropores contained in the porous nano-network structure is 0.3nm~0.6nm; The metal sintered body includes at least one of a nano nickel powder light sintered body, a nano silver powder light sintered body and a nano aluminum powder light sintered body.

2. The method for preparing a hydrogen separation membrane according to claim 1, characterized in that: The polymer includes polyacrylonitrile and / or polyimide.

3. The method for preparing a hydrogen separation membrane according to claim 1, characterized in that: Before the casting solution is made into a fiber membrane precursor by a spinning process, the method further comprises: Mixing and stirring the polymer, the organic solvent and the nanocellulose at 100° C. to 180° C. to obtain a premix; The premix is ​​mixed with the porous material, heated and stirred to form a homogeneous film casting solution.

4. The method for preparing a hydrogen separation membrane according to any one of claims 1 to 3, characterized in that: The conditions of the heat treatment are: the heat treatment temperature is 600° C. to 1000° C., and the heat treatment holding time is 2 h to 5 h.

5. A hydrogen separation membrane, characterized in that: The hydrogen separation membrane is prepared according to the method for preparing a hydrogen separation membrane according to any one of claims 1 to 4.

6. The hydrogen separation membrane according to claim 5, characterized in that The carbon-based fiber membrane includes a hollow fiber-shaped carbon-based fiber membrane and / or a flat-plate-shaped carbon-based fiber membrane.

7. The hydrogen separation membrane according to claim 5, characterized in that The metal sintered body has a hydrogen adsorption function, and the specific surface area of ​​the metal sintered body is 20m 2 / g~27m 2 / g, the particle size of the metal sintered body is 10nm~20nm, and the pore size of the zeolite molecular sieve is less than 3Å.

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