A tubular two-dimensional MXene membrane and its preparation method and application in gas separation

Abstract

The present invention discloses a tubular two-dimensional MXene membrane, a preparation method thereof, and an application thereof in gas separation. The preparation method comprises the following steps: (1) pretreating a porous substrate; (2) synthesizing a two-dimensional MXene nanosheet solution and preparing an electrophoretic deposition experimental device; (3) placing the pretreated porous substrate in a self-made electrophoretic deposition experimental device to prepare a tubular two-dimensional MXene membrane preliminary product; (4) drying and activating the tubular two-dimensional MXene membrane preliminary product prepared in step (3) to obtain a finished tubular two-dimensional MXene membrane. The preparation method of the present invention is simple and efficient, low in cost, highly repeatable, and easy to prepare on a large scale. The tubular two-dimensional MXene membrane prepared by the present invention has good performance in terms of H 2 / CO 2 The separation shows high selectivity and good hydrothermal stability, and has good potential for industrial scale-up application in the field of gas separation.

Description

Technical Field

[0001] The present invention belongs to the field of two-dimensional nanomembrane preparation technology and gas separation technology, and specifically relates to a tubular two-dimensional MXene membrane and a preparation method thereof and application in gas separation. Background Art

[0002] As we all know, hydrogen is one of the greenest and most environmentally friendly clean fuels in the world. It can replace traditional fossil energy to reduce environmental pollution caused by excessive greenhouse gas emissions. At present, the main industrial hydrogen separation and purification processes are pressure swing adsorption and cryogenic distillation processes. These processes are not only relatively complex to operate, but also consume huge amounts of energy. In recent years, with the development of membrane separation technology, membrane separation technology with the advantages of high separation efficiency, low operating energy consumption, and high operational flexibility has gradually been applied to the field of gas separation, showing good application prospects. However, traditional polymer separation membranes generally have a trade-off effect of permeability and selectivity, and the two cannot be achieved at the same time. Separation membranes based on new two-dimensional materials can achieve the optimization of permeability and selectivity because their assembly unit size / physical and chemical properties and interlayer spacing can be adjusted separately, thereby achieving the optimization of permeability and selectivity, which is expected to break through the bottleneck limitation of the upper limit of traditional polymer membrane separation.

[0003] Two-dimensional transition metal carbides / nitrides (MXene for short) are a young family of two-dimensional materials with a general formula of M n+1 X n T x(n = 1, 2, 3 or 4), where M represents transition metals (such as Ti, V, Mo and Cr), X represents carbon and / or nitrogen, and T represents functional groups (such as O, F, OH, Cl). Since MXene materials have high aspect ratios, good mechanical strength and flexibility, and a uniform free layer spacing cavity of 0.35nm, their application in the field of gas separation has become possible, and they are an excellent membrane material based on size screening. Although two-dimensional MXene membranes have been reported in the field of gas separation, most of the research is conducted on fragile substrates such as flaky anodized aluminum oxide AAO or α-Al2O3, which is not scalable. For example, the literature reports [Shen J, Liu GZ, Ji YF, et al. 2D MXene nanofilms with tunable gas transport channels. Adv Funct Mater. 2018; 28 (31): 1801511.], however, in actual industrial applications, tubular substrate membranes are more commonly used, which have the advantages of small footprint and large membrane area per unit volume. However, the current two-dimensional membrane preparation methods are limited to filtration, spin coating, drop coating, dipping and other methods. There are problems such as single membrane preparation method, poor membrane preparation repeatability and low membrane preparation efficiency. The membrane prepared by filtration may take several hours or even more than ten hours, and the membrane preparation efficiency is too low. As described in the literature [Qu K, Dai LH, Xia YS, et al. Self-crosslinked MXene hollow fiber membranes for H2 / CO2separation.J Membr Sci.2021;638:119669.],At the same time, due to the curvature problem of tubular membranes, defects are more likely to occur during the preparation process, and it is more difficult to prepare two-dimensional membranes with good performance. Therefore, how to efficiently prepare tubular two-dimensional MXene membranes with high selectivity, permeability and stability has become a problem that needs to be solved urgently in research. Summary of the invention

[0004] In order to effectively solve the problems of long preparation process of tubular two-dimensional MXene membranes in practical applications, low membrane performance selectivity, permeability and stability, the primary purpose of the present invention is to provide a method for preparing tubular two-dimensional MXene membranes. The preparation method is simple, efficient, low-cost and highly repeatable. It only takes 2 to 10 minutes to grow a layer of MXene dense membrane with a thickness of about 200 to 1000 nm on a porous substrate, which is suitable for large-scale production.

[0005] The second object of the present invention is to provide a tubular two-dimensional MXene film prepared by the above preparation method.

[0006] The third purpose of the present invention is to provide an application of the tubular two-dimensional MXene membrane in gas separation, specifically for the separation of hydrogen and gas molecules with different kinetic diameters and characteristics.

[0007] The primary purpose of the present invention is achieved through the following technical solutions:

[0008] A method for preparing a tubular two-dimensional MXene film comprises the following steps:

[0009] (1) Pre-treating the porous substrate by first grinding the porous substrate, then ultrasonically cleaning it with a surface cleaning agent, anhydrous ethanol, and deionized water, and then applying a carbon nanotube (CNT) solution after ultrasonication to modify and fill the holes on the surface of the porous substrate;

[0010] (2) Synthesize two-dimensional MXene nanosheet solution and prepare electrophoretic deposition experimental device;

[0011] (3) placing the porous substrate pretreated in step (1) in a self-made electrophoretic deposition experimental device to prepare a tubular two-dimensional MXene membrane primary product;

[0012] (4) Drying and activating the initial tubular two-dimensional MXene membrane product prepared in step (3) to obtain a finished tubular two-dimensional MXene membrane.

[0013] Preferably, the porous substrate described in step (1) is one of a porous stainless steel tube, a porous stainless steel mesh, a stainless steel hollow fiber, a porous nickel mesh, a porous copper mesh, polyvinylidene fluoride (PVDF), polyamide (PA), polyether sulfone (PES), sulfonated polyether sulfone (SPES), polysulfone (PSF) or sulfonated polysulfone (SPSF).

[0014] Preferably, in step (1), the mass volume ratio of the porous substrate, surface cleaning agent, anhydrous ethanol and deionized water is 1g:10-30ml:10-25ml:10-25ml, the number of ultrasonic cleaning is 1-5 times, the frequency of ultrasonic cleaning is 20-100kHz, and the ultrasonic time is 10-60min; the concentration of the carbon nanotube solution is 0.01-0.05mg / ml, and the number of filtration is 1-4 times.

[0015] Preferably, the specific steps of synthesizing the two-dimensional MXene nanosheet solution in step (2) are to mix the raw materials MAX, LiF and high-concentration hydrochloric acid solution in a mass volume ratio of 0.5-3.0 g: 1.0-5.0 g: 30-80 ml, magnetically stir, and react to synthesize the two-dimensional MXene nanosheet solution; the synthesis temperature is 25-70° C., the magnetic stirring speed is 20-50 r / min, and the synthesis reaction time is 20-48 h.

[0016] Preferably, the mass concentration of the two-dimensional MXene nanosheet solution in the electrophoretic deposition experimental device in step (3) is 0.1-2.0 mg / ml, the voltage is 1-30 V, the current is 0.001-0.010 A, and the electrophoresis time is 0.5-10 min.

[0017] Preferably, the drying method of the two-dimensional MXene film in step (4) is natural ventilation drying, room temperature vacuum drying or low temperature vacuum drying, the drying temperature is 25 to 100° C., and the drying time is 6 to 48 hours. The activation method is vacuum activation or ventilation activation, the activation temperature is 50 to 120° C., and the activation time is 6 to 24 hours.

[0018] The second object of the present invention is achieved by the following technical solutions:

[0019] A tubular two-dimensional MXene membrane prepared according to the above preparation method.

[0020] Preferably, the thickness of the tubular two-dimensional MXene film is 200 to 1000 nm.

[0021] The third object of the present invention is achieved by the following technical solutions:

[0022] A tubular two-dimensional MXene membrane for gas separation applications.

[0023] Specifically, the tubular two-dimensional MXene membrane was assembled into a homemade stainless steel gas membrane separator for gas separation testing.

[0024] Preferably, the type of separation gas is one or two of hydrogen (H2, 0.29nm), carbon dioxide (CO2, 0.33nm), nitrogen (N2, 0.36nm), methane (CH4, 0.38nm), ethylene (C2H4, 0.39nm), propylene (C3H6, 0.40nm), ethane (C2H6, 0.42nm), and propane (C3H8, 0.43nm); when two components of separation gas are selected, the volume ratio of the separation gas is 1:1, the total flow rate is 50-200ml, and the purge gas is one of argon (Ar), helium (He), and methane (CH4), and the total flow rate is 20-100ml.

[0025] The final gas separation performance of the present invention is calculated after detection by Agilent gas chromatograph 7890A.

[0026] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0027] (1) The present invention uses electrophoretic deposition technology to efficiently prepare a tubular two-dimensional MXene membrane with good gas separation selectivity, flux and stability, and the membrane thickness is only 200 to 1000 nm. The membrane has great application prospects for industrial scale-up.

[0028] (2) The present invention greatly shortens the preparation time of tubular two-dimensional MXene membranes, and has high preparation efficiency (within 2 to 10 minutes) and simple process operation, providing powerful conditions for further scale-up preparation of two-dimensional MXene membranes.

[0029] (3) The tubular two-dimensional MXene membranes prepared in the present invention are all prepared on commercial porous substrates. The experimental process is closer to the conditions of real industrial applications, the experimental data is highly reliable, the prepared membranes are highly reproducible, the cost is low, and it is easier to scale up the preparation.

[0030] (4) When the tubular two-dimensional MXene membrane prepared in the present invention is used for gas separation, especially the separation of H2 / CO2, it can show good gas separation selectivity and flux and excellent hydrothermal and long-term stability (>1000h), which is very suitable for industrial large-scale production and has good industrial scale-up application potential in the field of gas separation. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a structural diagram of a homemade stainless steel gas membrane separator in this embodiment;

[0032] Figure 2 The performance diagram of different gases in Example 1;

[0033] Figure 3 This is a scanning electron microscope (SEM) image of the cross-section of the tubular two-dimensional MXene membrane of Example 4. DETAILED DESCRIPTION

[0034] The present invention is further described in detail below in conjunction with examples, but the implementation mode and protection scope of the present invention are not limited thereto.

[0035] The present invention Figure 1 The structure diagram of the homemade stainless steel gas membrane separator in this embodiment. The homemade stainless steel gas membrane separator used in the embodiment of the present invention comprises a tube side and a shell side. The two ends of the tube side are respectively provided with a tube side outlet and a tube side inlet. The two ends of the shell side are respectively provided with a shell side inlet and a shell side outlet. The shell side inlet and the tube side inlet are arranged on the same side, and the shell side outlet and the tube side outlet are arranged on the same side. The specific dimensions of the homemade stainless steel gas membrane separator are as follows: Figure 1The unit is millimeter (mm). A gas separation test was conducted by encapsulating a tubular two-dimensional MXene membrane into a homemade stainless steel gas membrane separator tube; the raw gas enters from the shell inlet, the retentate gas exits from the shell outlet, the purge gas enters from the tube inlet, mixes with the permeate gas, and finally exits from the tube outlet.

[0036] Example 1

[0037] The method for preparing the tubular two-dimensional MXene film described in this embodiment comprises the following steps:

[0038] (1) Pre-treating the porous tubular stainless steel substrate: first, grinding the porous substrate, and then placing it in a surface cleaning agent, anhydrous ethanol, and deionized water for ultrasonic cleaning, respectively, with a mass volume ratio of 1g:15ml:15ml:15ml, the number of cleanings is 3 times, the concentration of the carbon nanotube solution is 0.02mg / ml, the number of pumping is 2 times, the frequency of the ultrasonic cleaning is 20-100kHz, and the time is 30min;

[0039] (2) Synthesis of two-dimensional MXene nanosheet solution: weigh the raw material MAX mass of 2.0 g, the mass of LiF of 2.5 g, the volume of high concentration hydrochloric acid solution of 50 ml, the synthesis conditions are temperature: 50 ° C, magnetic stirring speed of 30 r / min, and reaction time of 30 h;

[0040] (3) The porous tubular stainless steel substrate treated in step (1) was placed in a homemade electrophoretic deposition experimental device to prepare a two-dimensional MXene film. The concentration of the electrophoretically deposited MXene nanosheets was 0.25 mg / ml, the voltage was 5 V, the current was 0.002 A, and the electrophoresis time was 2.5 min;

[0041] (4) Drying and activating the tubular two-dimensional MXene film prepared in step (3). The drying method is low-temperature vacuum drying, the drying temperature is 60°C, and the drying time is 12 hours. The activation method is vacuum activation, the activation temperature is 90°C, and the activation time is 12 hours.

[0042] The tubular two-dimensional MXene membrane prepared in this example is used in gas separation:

[0043] The prepared tubular two-dimensional MXene membrane was encapsulated into a homemade stainless steel gas membrane separator for gas separation test. The types of raw gas are hydrogen (H2, 0.29nm), carbon dioxide (CO2, 0.33nm), nitrogen (N2, 0.36nm), methane (CH4, 0.38nm), ethylene (C2H4, 0.39nm), propylene (C3H6, 0.40nm), ethane (C2H6, 0.42nm), propane (C3H8, 0.43nm) One or two of them, the volume ratio of the two-component mixed raw gas is 1:1, the total flow rate is 100ml, and the purge gas is one of argon (Ar), helium (He), and methane (CH4), with a total flow rate of 50ml. The gas separation performance is calculated after detection by Agilent gas chromatograph 7890A.

[0044] The gas flux in the experimental test parameters is represented by P, the unit is GPU, 1GPU = 3.35×10 -10 mol·m -2 ·s -1 ·pa -1 , the gas fluxes are P(H2)=1450GPU, P(CO2)=22GPU, P(N2)=61GPU, P(CH4)=45GPU, P(C2H4)=8GPU, then the gas selectivities corresponding to H2 / CO2, H2 / N2, H2 / CH4, H2 / C2H4 are 64.9, 23.9, 32.6, 186.4 respectively. The experimental results are as follows Figure 2 shown.

[0045] Example 2

[0046] The method for preparing the tubular two-dimensional MXene film described in this embodiment comprises the following steps:

[0047] (1) Pre-treating the porous tubular stainless steel substrate: first, grinding the porous substrate, and then placing it in a surface cleaning agent, anhydrous ethanol, and deionized water for ultrasonic cleaning, respectively, with a mass volume ratio of 1g:15ml:15ml:15ml, the number of cleanings is 3 times, the concentration of the carbon nanotube solution is 0.02mg / ml, the number of pumping is 2 times, the frequency of the ultrasonic cleaning is 20-100kHz, and the time is 30min;

[0048] (2) Synthesis of two-dimensional MXene nanosheet solution: weigh the raw material MAX mass of 2.0 g, the mass of LiF of 2.5 g, the volume of high concentration hydrochloric acid solution of 50 ml, the synthesis conditions are temperature: 50 ° C, magnetic stirring speed of 30 r / min, and reaction time of 30 h;

[0049] (3) The porous tubular stainless steel substrate treated in step (1) was placed in a homemade electrophoretic deposition experimental device to prepare a two-dimensional MXene film. The concentration of the electrophoretically deposited MXene nanosheets was 0.25 mg / ml, the voltage was 5 V, the current was 0.002 A, and the electrophoresis time was 1.5 min;

[0050] (4) Drying and activating the tubular two-dimensional MXene film prepared in step (3). The drying method is low-temperature vacuum drying, the drying temperature is 60°C, and the drying time is 12 hours. The activation method is vacuum activation, the activation temperature is 90°C, and the activation time is 12 hours.

[0051] The tubular two-dimensional MXene membrane prepared in this example is used in gas separation:

[0052] The prepared tubular stainless steel two-dimensional MXene membrane was encapsulated into a homemade stainless steel gas membrane separator for gas separation testing. The raw gas was hydrogen (H2) and carbon dioxide (CO2), the total flow rate of the raw gas was 100ml, the volume ratio was 1:1, and the purge gas was argon (Ar), with a total flow rate of 50ml. The gas separation performance was calculated after detection by Agilent gas chromatograph 7890A.

[0053] The gas fluxes tested in the experiment were P(H2)=1579GPU, P(CO2)=191GPU, and the H2 / CO2 gas selectivity was 7.

[0054] Example 3

[0055] The method for preparing the tubular two-dimensional MXene film described in this embodiment comprises the following steps:

[0056] (1) Pre-treating the porous tubular stainless steel substrate: first, grinding the porous substrate, and then placing it in a surface cleaning agent, anhydrous ethanol, and deionized water for ultrasonic cleaning, respectively, with a mass volume ratio of 1g:15ml:15ml:15ml, the number of cleanings is 3 times, the concentration of the carbon nanotube solution is 0.02mg / ml, the number of pumping is 2 times, the frequency of the ultrasonic cleaning is 20-100kHz, and the time is 30min;

[0057] (2) Synthesis of two-dimensional MXene nanosheet solution: weigh the raw material MAX mass of 2.0 g, the mass of LiF of 2.5 g, the volume of high concentration hydrochloric acid solution of 50 ml, the synthesis conditions are temperature: 50 ° C, magnetic stirring speed of 30 r / min, and reaction time of 30 h;

[0058] (3) The porous tubular stainless steel substrate treated in step (1) was placed in a homemade electrophoretic deposition experimental device to prepare a two-dimensional MXene film. The concentration of the electrophoretically deposited MXene nanosheets was 0.25 mg / ml, the voltage was 5 V, the current was 0.002 A, and the electrophoresis time was 4 min;

[0059] (4) Drying and activating the tubular two-dimensional MXene film prepared in step (3). The drying method is low-temperature vacuum drying, the drying temperature is 60°C, and the drying time is 12 hours. The activation method is vacuum activation, the activation temperature is 90°C, and the activation time is 12 hours.

[0060] The tubular two-dimensional MXene membrane prepared in this example is used in gas separation:

[0061] The prepared tubular stainless steel two-dimensional MXene membrane was encapsulated into a homemade stainless steel gas membrane separator for gas separation testing. The raw gas was hydrogen (H2) and carbon dioxide (CO2), the total flow rate of the raw gas was 100ml, the volume ratio was 1:1, and the purge gas was argon (Ar), with a total flow rate of 50ml. The gas separation performance was calculated after detection by Agilent gas chromatograph 7890A.

[0062] The gas fluxes tested in the experiment were P(H2)=621GPU and P(CO2)=17GPU, respectively, so the H2 / CO2 gas selectivity was 55.

[0063] Example 4

[0064] The method for preparing the tubular two-dimensional MXene film described in this embodiment comprises the following steps:

[0065] (1) Pre-treating the porous tubular stainless steel mesh substrate: placing the substrate in a surface cleaning agent, anhydrous ethanol, and deionized water for ultrasonic cleaning, respectively, with a mass volume ratio of 1 g: 10 ml: 10 ml: 10 ml, and the number of cleanings is 3 times. The frequency of the ultrasonic cleaning is 20-100 kHz, and the time is 30 min;

[0066] (2) Synthesis of two-dimensional MXene nanosheet solution: weigh the raw material MAX mass of 2.0 g, the mass of LiF of 2.5 g, the volume of high concentration hydrochloric acid solution of 50 ml, the synthesis conditions are temperature: 50 ° C, magnetic stirring speed of 30 r / min, and reaction time of 30 h;

[0067] (3) The porous stainless steel mesh substrate treated in step (1) was placed in a homemade electrophoretic deposition experimental device to prepare a two-dimensional MXene film. The concentration of the electrophoretically deposited MXene nanosheets was 1.0 mg / ml, the voltage was 5 V, the current was 0.005 A, and the electrophoresis time was 2.5 min.

[0068] (4) Drying and activating the tubular stainless steel mesh two-dimensional MXene membrane prepared in step (3). The drying method is room temperature vacuum drying, the drying temperature is 25°C, and the drying time is 12 hours. The activation method is vacuum activation, the activation temperature is 60°C, and the activation time is 12 hours. The prepared membrane is characterized by cross-sectional scanning electron microscopy. The membrane thickness of the cross section is approximately 800 nm. Figure 3 shown.

[0069] The tubular two-dimensional MXene membrane prepared in this example is used in gas separation:

[0070] The prepared tubular stainless steel mesh two-dimensional MXene membrane was encapsulated into a homemade stainless steel gas membrane separator for gas separation testing. The raw gas was hydrogen (H2) and carbon dioxide (CO2), the total flow rate of the raw gas was 100ml, the volume ratio was 1:1, and the purge gas was argon (Ar), with a total flow rate of 50ml. The gas separation performance was calculated after detection by Agilent gas chromatograph 7890A.

[0071] The gas fluxes tested in the experiment were P(H2)=116GPU, P(CO2)=2GPU, and the H2 / CO2 gas selectivity was 76.8.

[0072] Example 5

[0073] The method for preparing the tubular two-dimensional MXene film described in this embodiment comprises the following steps:

[0074] (1) Pre-treating the porous tubular nickel mesh substrate: placing the substrate in a surface cleaning agent, anhydrous ethanol, and deionized water for ultrasonic cleaning, respectively, with a mass volume ratio of 1 g: 10 ml: 10 ml: 10 ml, the number of cleanings is 3 times, the frequency of the ultrasonic cleaning is 20-100 kHz, and the time is 30 min;

[0075] (2) Synthesis of two-dimensional MXene nanosheet solution: weigh the raw material MAX mass of 2.0 g, the mass of LiF of 2.5 g, the volume of high concentration hydrochloric acid solution of 50 ml, the synthesis conditions are temperature: 50 ° C, magnetic stirring speed of 30 r / min, and reaction time of 30 h;

[0076] (3) The tubular nickel mesh substrate treated in step (1) was placed in a homemade electrophoretic deposition experimental device to prepare a two-dimensional MXene film. The concentration of the electrophoretically deposited MXene nanosheets was 1.0 mg / ml, the voltage was 5 V, the current was 0.005 A, and the electrophoresis time was 1.5 min.

[0077] (4) Drying and activating the tubular nickel mesh two-dimensional MXene film prepared in step (3). The drying method is room temperature vacuum drying, the drying temperature is 25° C., and the drying time is 12 h. The activation method is vacuum activation, the activation temperature is 60° C., and the activation time is 12 h.

[0078] The tubular two-dimensional MXene membrane prepared in this example is used in gas separation:

[0079] The prepared tubular nickel mesh two-dimensional MXene membrane was encapsulated into a homemade stainless steel gas membrane separator for gas separation testing. The raw gas was hydrogen (H2) and carbon dioxide (CO2), the total flow rate of the raw gas was 100ml, the volume ratio was 1:1, and the purge gas was argon (Ar), with a total flow rate of 50ml. The gas separation performance was calculated after detection by Agilent gas chromatograph 7890A.

[0080] The gas fluxes tested in the experiment were P(H2)=378GPU and P(CO2)=15GPU, respectively, so the H2 / CO2 gas selectivity was 24.8.

[0081] Example 6

[0082] The method for preparing the tubular two-dimensional MXene film described in this embodiment comprises the following steps:

[0083] (1) Pre-treating a porous polyvinylidene fluoride (PVDF) substrate: placing the substrate in a surface cleaning agent, anhydrous ethanol, and deionized water for ultrasonic cleaning, respectively, with a mass volume ratio of 1 g: 10 ml: 10 ml: 10 ml, the number of cleanings being 3 times, the frequency of the ultrasonic cleaning being 20-100 kHz, and the time being 30 min;

[0084] (2) Synthesis of two-dimensional MXene nanosheet solution: weigh the raw material MAX mass of 2.0 g, the mass of LiF of 2.5 g, the volume of high concentration hydrochloric acid solution of 50 ml, the synthesis conditions are temperature: 50 ° C, magnetic stirring speed of 30 r / min, and reaction time of 30 h;

[0085] (3) The tubular polyvinylidene fluoride substrate treated in step (1) was placed in a homemade electrophoretic deposition experimental device to prepare a two-dimensional MXene film. The concentration of the electrophoretically deposited MXene nanosheets was 1.5 mg / ml, the voltage was 5 V, the current was 0.010 A, and the electrophoresis time was 2.5 min.

[0086] (4) Drying and activating the tubular polyvinylidene fluoride two-dimensional MXene film prepared in step (3). The drying method is room temperature vacuum drying, the drying temperature is 25° C., and the drying time is 12 h. The activation method is vacuum activation, the activation temperature is 60° C., and the activation time is 12 h.

[0087] The tubular two-dimensional MXene membrane prepared in this example is used in gas separation:

[0088] The prepared tubular polyvinylidene fluoride two-dimensional MXene membrane was encapsulated into a homemade stainless steel gas membrane separator for gas separation testing. The raw gas was hydrogen (H2) and carbon dioxide (CO2), the total flow rate of the raw gas was 100ml, the volume ratio was 1:1, and the purge gas was argon (Ar), with a total flow rate of 50ml. The gas separation performance was calculated after detection by Agilent gas chromatograph 7890A.

[0089] The gas fluxes tested in the experiment were P(H2)=586GPU and P(CO2)=41GPU, respectively, so the H2 / CO2 gas selectivity was 37.3.

[0090] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A method for preparing a tubular two-dimensional MXene membrane for gas separation, characterized in that: The following steps are involved: (1) Pre-treating the porous substrate by first grinding the porous substrate, then ultrasonically cleaning it with a surface cleaning agent, anhydrous ethanol, and deionized water, and then applying the ultrasonicated carbon nanotube (CNT) solution to modify and fill the holes on the surface of the porous substrate; (2) Synthesize two-dimensional MXene nanosheet solution and prepare electrophoretic deposition experimental equipment; (3) placing the porous substrate pretreated in step (1) in a homemade electrophoretic deposition experimental device to prepare a tubular two-dimensional MXene membrane primary product; (4) drying and activating the tubular two-dimensional MXene membrane product prepared in step (3) to obtain a finished tubular two-dimensional MXene membrane; The activation method in the activation treatment in step (4) is vacuum activation or ventilation activation, the activation temperature is 50-120°C, and the activation time is 6-24 hours.

2. The method for preparing a tubular two-dimensional MXene membrane for gas separation according to claim 1, characterized in that: The porous substrate described in step (1) is one of a porous stainless steel tube, a porous stainless steel mesh, a stainless steel hollow fiber, a porous nickel mesh, a porous copper mesh, polyvinylidene fluoride, polyamide, polyether sulfone, sulfonated polyether sulfone, polysulfone or sulfonated polysulfone.

3. The method for preparing a tubular two-dimensional MXene membrane for gas separation according to claim 1, characterized in that: The mass volume ratio of the porous substrate, surface cleaning agent, anhydrous ethanol and deionized water in step (1) is 1 g:10~30 ml:10~25 ml:10~25 ml, the number of ultrasonic cleaning is 1~5 times, the frequency of ultrasonic cleaning is 20~100 kHz, and the ultrasonic time is 10~60 min; the concentration of the carbon nanotube solution is 0.01~0.05 mg / ml, and the number of pumping is 1~4 times.

4. The method for preparing a tubular two-dimensional MXene membrane for gas separation according to claim 1, characterized in that: The specific steps of synthesizing the two-dimensional MXene nanosheet solution described in step (2) are to mix the raw materials MAX, LiF and high-concentration hydrochloric acid solution in a mass volume ratio of 0.5~3.0 g:1.0~5.0 g:30~80 ml, magnetically stir, and react to synthesize the two-dimensional MXene nanosheet solution; the synthesis temperature is 25~70°C, the magnetic stirring speed is 20~50 r / min, and the synthesis reaction time is 20~48h.

5. The method for preparing a tubular two-dimensional MXene membrane for gas separation according to claim 1, characterized in that: The mass concentration of the two-dimensional MXene nanosheet solution in the electrophoretic deposition experimental device in step (3) is 0.1~2.0 mg / ml, the voltage is 1~30 V, the current is 0.001~0.010 A, and the electrophoresis time is 0.5~10 min.

6. The method for preparing a tubular two-dimensional MXene membrane for gas separation according to claim 1, characterized in that: The drying method of the two-dimensional MXene film in step (4) is natural ventilation drying, room temperature vacuum drying or low temperature vacuum drying, the drying temperature is 25~100°C, and the drying time is 6~48 hours.

7. A tubular two-dimensional MXene membrane for gas separation prepared according to the preparation method according to any one of claims 1 to 6.

8. The tubular two-dimensional MXene membrane for gas separation according to claim 7, characterized in that: The thickness of the tubular two-dimensional MXene film is 200~1000 nm.

9. Use of the tubular two-dimensional MXene membrane for gas separation according to claim 7 in gas separation, characterized in that: The tubular two-dimensional MXene membrane was assembled into a homemade stainless steel gas membrane separator for gas separation testing.

10. Use of the tubular two-dimensional MXene membrane for gas separation according to claim 9 in gas separation, characterized in that: The type of separation gas is one or two of hydrogen, carbon dioxide, nitrogen, methane, ethylene, propylene, ethane, and propane; when two components of separation gas are selected, the separation gas volume ratio is 1:1, and the purge gas is one of argon, helium, and methane.

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