A method for preparing carbon molecular sieve membrane by mechanical rubbing coating process and application

Abstract

The application provides a method for preparing a carbon molecular sieve membrane by a mechanical rubbing coating process and application, and the method comprises the following steps: fixing a porous carrier with a surface wetting, placing a cylindrical pencil core on the surface of the porous carrier, and the particle size of the surface of the porous carrier is greater than or equal to 2 mu m; using an automatic rubbing coating equipment for rubbing coating, moving the pencil core horizontally in the spin coating process, and finally preparing a continuous and dense carbon molecular sieve membrane through repeated rubbing coating. The mechanical rubbing coating process is applied to the construction of the carbon molecular sieve membrane, the problems of complex preparation process and high cost of the carbon molecular sieve membrane are overcome, and the carbon molecular sieve membrane with good continuity, high repeatability and excellent separation performance is prepared. In addition, the pencil core and other carbon-based materials are developed for use as a membrane material, and the pencil core and other carbon-based materials have the characteristics of being cheap, easy to obtain and green and environmentally friendly, meanwhile, the pencil marks have the erasability, which is helpful to realize the reuse of the carrier. In a word, the application provides a simple, green and economical preparation scheme of the carbon molecular sieve membrane, and the application has a good industrial application prospect.

Description

Technical Field

[0001] This invention belongs to the field of membrane separation technology, and in particular relates to a method and application of preparing carbon molecular sieve membranes by mechanical wiping process. Background Technology

[0002] The production and use of dyes generate large amounts of dyeing and printing wastewater, which contains organic matter that is extremely difficult to biodegrade. Direct discharge of such wastewater without treatment would cause enormous damage to the ecological environment. Compared with traditional water treatment processes, membrane separation technology has gradually developed in recent decades and has become a research hotspot in the field of water treatment due to its advantages such as excellent separation effect, less secondary pollution, small footprint, and simple operation.

[0003] Membrane materials, as the core of membrane separation technology, play a crucial role in separation performance. Molecular sieve membranes, such as zeolite membranes, metal-organic framework (MOF) membranes, covalent organic framework (COF) membranes, and carbon molecular sieve (CMS) membranes, offer significant advantages over widely used polymer membranes in terms of high separation efficiency, good thermal / chemical stability, and long-term durability. Among them, carbon molecular sieve membranes, with their molecular-sized slit-like transport pathways, have been extensively studied and show potential applications in gas separation, reverse osmosis, and nanofiltration. Carbon molecular sieve membranes are typically made by carbonizing polymers, making them attractive for gas separation. However, the polymers require high-temperature (900–1200℃) carbonization, which is not only energy-intensive but also costly, limiting the industrial application of carbon molecular sieve membranes. Therefore, there is an urgent need to develop a simple, green, and economical method for preparing carbon molecular sieve membranes. Summary of the Invention

[0004] Pencil leads, such as graphite leads, pencil leads, and charcoal leads, possess mature manufacturing processes and low production costs. Taking pencil leads as an example, they are mainly composed of layered graphite and intercalated nano-clay particles. During the production process, the graphite and clay are thoroughly stirred, reducing the original order of the graphite flakes and forming graphite microcrystals of varying sizes, which provides a basis for molecular sieve separation. Subsequently, the addition of wax fills the gaps between the graphite and clay, increasing the adhesion between adjacent graphite flakes and ensuring continuous pencil marks. Inspired by the presence of laminated graphite in pencil leads, we attempted to prepare carbon molecular sieve membranes using a mechanical coating process. This process is simple, environmentally friendly, and inexpensive, with broad application prospects.

[0005] The mechanical wiping process uses friction as the driving force for preparing carbon molecular sieve membranes. It features self-inhibiting growth, allowing graphite microcrystals to fill defective areas on the porous carrier, thus avoiding damage to the already filled structure. During preparation, as the peeled-off powder adheres to the porous carrier, the surface roughness decreases, reducing the friction between the carrier and the pencil lead. When a smooth, continuous carbon molecular sieve membrane forms on the carrier surface, the surface roughness becomes nanoscale, and the friction is insufficient to peel off the pencil lead further, at which point the carbon molecular sieve membrane stops spreading. Furthermore, this process requires a certain degree of surface roughness on the porous carrier, reducing the quality requirements and further lowering the membrane preparation cost. Simultaneously, the erasable nature of pencil marks effectively solves the carrier contamination and waste problem faced in industrial applications, allowing the carrier to be reused after simple mechanical erasure.

[0006] The purpose of this invention is to develop a simple, green, and economical method for preparing carbon molecular sieve membranes through a mechanical coating process. After wetting the surface of a porous carrier, the carbon material on the surface of the pen refill is peeled off by the frictional force between the pen refill and the carrier, and then adheres to the surface of the carrier, thus successfully preparing a carbon molecular sieve membrane for nanofiltration on the porous carrier. The self-inhibited growth characteristics of this preparation process are beneficial for producing carbon molecular sieve membranes with good intergrowth, high repeatability, and excellent separation performance, thereby effectively solving the key problems faced by carbon molecular sieve membranes in industrial applications, such as production cost and large-scale production.

[0007] The technical solution of this invention is:

[0008] A method for preparing carbon molecular sieve membranes using a mechanical coating process includes the following steps:

[0009] (1) Fix a porous carrier whose surface has been wetted with an organic solvent, and place a cylindrical pen refill on the surface of the porous carrier; the particle size of the porous carrier surface is greater than or equal to 2 μm;

[0010] (2) Use an automatic wiping device to perform wiping. During the spin coating process, move the pen tip horizontally to ensure that it can be evenly wiped onto the porous carrier surface. After repeated wiping, a continuous and dense carbon molecular sieve membrane is finally prepared.

[0011] Preferably, the carbon molecular sieve membrane obtained in step (2) is washed and then dried.

[0012] The porous support described in preferred step (1) specifically includes porous metal oxides, porous glass, porous non-metallic oxides, porous metals, or porous polymers; the structure of the porous support includes a disc structure, a plate structure, a tubular structure, or a spiral structure, and the particle size on the surface of the porous support is 2 μm to 100 μm. Further, the porous support is a porous metal oxide, such as porous alumina or porous titanium dioxide, and the structure of the porous support adopts a disc structure, a plate structure, or a tubular structure. Even further, the porous support uses disc-shaped or tubular porous alumina, and the alumina particle size on the surface of the porous support is 3 to 10 μm.

[0013] The organic solvent in preferred step (1) includes one or more of the following: low-carbon alcohols (such as methanol and ethanol), low-carbon organic acids (such as formic acid and acetic acid), low-carbon esters (such as ethyl acetate), low-carbon ketones (such as acetone), and low-carbon amides (such as N,N-dimethylformamide). Further, ethanol is used as the solvent in the wetting process.

[0014] Preferably, the solvent used in the wetting process described in step (1) is a low-carbon alcohol solution of a crosslinking agent, wherein the types of crosslinking agents include: polyethyleneimine and tannic acid, polyvinyl alcohol, polyvinyl butyral, or a mixture of polyethyleneimine. Further, the crosslinking agent used is polyethyleneimine with tannic acid, and the mass concentration is 0–5 g / L.

[0015] The preferred contact area between the cylindrical pen tip and the carrier surface in step (1) is 0.01–100 mm². 2 Furthermore, the contact area between the pen refill and the carrier surface is 0.25–25 mm. 2 Furthermore, the contact area between the pen refill and the carrier surface is 1–9 mm. 2 ...

[0016] The preferred equipment for automatic coating in step (2) specifically includes a spin coater or a multi-functional lathe.

[0017] In step (2), the preferred spin coating speed is 500 to 5000 rpm. Further, the spin coating speed is 3000 to 4000 rpm.

[0018] In preferred step (2), the spin coating time per unit area of ​​the carrier is 10–750 s / cm. 2 Furthermore, the spin-coating time per unit area of ​​the carrier is 30–350 s / cm. 2 .

[0019] The preferred option in step (2) is to use graphite cores, pencil cores, or charcoal cores. Specifically, graphite cores are primarily composed of graphite; pencil cores are primarily composed of graphite, clay, and wax, and are classified by hardness into various grades such as 10B, 9B, 8B, 7B, 6B, 5B, 4B, 3B, 2B, B, HB, F, H, 2H, 3H, 4H, 5H, 6H, 7H, 8H, 9H, and 10H; charcoal cores are primarily composed of charcoal and graphite, and are classified by hardness into various grades such as HB, 2B, 4B, 6B, 7B, and 8B. Even further, the pencil core is a pencil core.

[0020] The present invention also provides the application of the carbon molecular sieve membrane prepared by the above preparation process in gas separation, dye retention or alcohol-water separation.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] (1) This invention provides a method for preparing carbon molecular sieve membranes using a mechanical wiping process, which can rapidly produce carbon molecular sieve membranes with good intergrowth and high repeatability. This preparation process uses friction as the driving force for preparing the carbon molecular sieve membrane. The self-inhibiting spreading characteristics during the preparation process cause graphite microcrystals to tend to accumulate at defective sites on the porous support, thereby avoiding damage to the already filled structure and facilitating the acquisition of a good membrane structure and high repeatability of separation performance. Simultaneously, based on the requirements of the preparation process on the surface roughness of the support, the requirements for support quality are reduced, thereby lowering the required cost.

[0023] (2) This invention uses carbon-based materials such as pencil leads, charcoal leads, and graphite leads as membrane materials, which are inexpensive, readily available, and environmentally friendly, avoiding the complex synthesis process and high cost of carbon-based materials. The erasability of pencil lead marks effectively solves the problem of carrier pollution and waste in industrial applications, allowing the carrier to be reused after simple mechanical erasure.

[0024] (3) The obtained carbon molecular sieve membrane has good applications in gas separation, dye retention or alcohol-water separation. Attached Figure Description

[0025] Figure 1 This is a scanning electron microscope (SEM) image of the carbon molecular sieve membrane prepared in Example 1 of the present invention;

[0026] Figure 2 The image shows the X-ray diffraction (XRD) pattern of the carbon molecular sieve membrane prepared in Example 1 of this invention.

[0027] Figure 3 This is a scanning electron microscope (SEM) image of the carbon molecular sieve membrane prepared in Example 2 of the present invention;

[0028] Figure 4The image shows the X-ray diffraction (XRD) pattern of the carbon molecular sieve membrane prepared in Example 2 of this invention.

[0029] Figure 5 This is a scanning electron microscope (SEM) image of the carbon molecular sieve membrane prepared in Example 3 of the present invention;

[0030] Figure 6 This is a cross-sectional scanning electron microscope (SEM) image of the carbon molecular sieve membrane prepared in Example 3 of the present invention;

[0031] Figure 7 The image shows the X-ray diffraction (XRD) pattern of the carbon molecular sieve membrane prepared in Example 3 of this invention.

[0032] Figure 8 This is a scanning electron microscope (SEM) image of the carbon molecular sieve membrane prepared in Example 4 of the present invention;

[0033] Figure 9 The image shows the X-ray diffraction (XRD) pattern of the carbon molecular sieve membrane prepared in Example 4 of this invention.

[0034] Figure 10 This is a scanning electron microscope (SEM) image of the carbon molecular sieve membrane prepared in Example 5 of the present invention;

[0035] Figure 11 This is a scanning electron microscope (SEM) image of the carbon molecular sieve membrane prepared in Example 11 of the present invention;

[0036] Figure 12 This is a scanning electron microscope (SEM) image of the carbon molecular sieve membrane prepared in Example 12 of the present invention;

[0037] Figure 13 This is a scanning electron microscope (SEM) image of the blank carrier in Comparative Example 1 of the present invention;

[0038] Figure 14 This is a scanning electron microscope (SEM) image of the carbon molecular sieve membrane prepared in Comparative Example 1 of the present invention;

[0039] Figure 15 This is a scanning electron microscope (SEM) image of the carbon molecular sieve membrane prepared in Comparative Example 2 of the present invention;

[0040] Figure 16 This is a scanning electron microscope (SEM) image of the carbon molecular sieve membrane prepared in Comparative Example 3 of the present invention;

[0041] Figure 17 This is a scanning electron microscope (SEM) image of the carbon molecular sieve membrane prepared in Comparative Example 4 of the present invention; Detailed Implementation

[0042] The present invention will be further described in detail below with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the present invention in any way. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0043] All raw materials used in the following embodiments of the present invention are commercially available products.

[0044] The spin coater used in Examples 1-5 and Comparative Examples 1-4 of this invention is all Shanghai Sanyan SYSC-300A.

[0045] The multi-functional lathe used in the following embodiments 11-12 of this invention is model WM210V.

[0046] Example 1

[0047] (1) Fix a disc-shaped porous alumina carrier with a surface particle size of about 5 μm in the center of the spin coater platform, cut one end of the Staedtler 6H pencil lead into a cylindrical pencil lead with a diameter of about 1.4 cm, and place it on the surface of the porous alumina carrier.

[0048] (2) The spin coater parameters were set as follows: rotation speed of 3000 rpm, and spin coating time per unit area of ​​the carrier of 45 s / cm. 2 The pre-absorption time is 3 seconds.

[0049] (3) Before spin coating, 1 ml of ethanol was dropped onto the surface of the porous alumina carrier. Then, while spin coating, the pencil lead was moved horizontally. This process was repeated once to finally prepare a continuous and dense carbon molecular sieve membrane.

[0050] (4) The carbon molecular sieve membrane obtained in step (3) is washed and then dried.

[0051] The composition of Staedtler 6H pencil lead is graphite:clay:wax = 44:48:8. The morphology of the prepared carbon molecular sieve membrane was observed under a scanning electron microscope (SEM). Figure 1 As shown, graphite is stacked in flake form, covering the surface of the alumina support, forming a continuous and dense film. XRD ( Figure 2 The spectrum shows only one strong diffraction peak at 26.4°, which corresponds to the diffraction peak of the (002) crystal plane of the graphite phase, proving that the graphite sheet is parallel to the plane of the support.

[0052] Example 2

[0053] The specific implementation steps are the same as in Example 1, except that the hardness grade of the pencil lead in step (2) is HB.

[0054] Staedtler HB pencil lead has a composition of graphite: clay: wax = 61:30:9. (SEM) Figure 3 The XRD results show that the graphite is stacked in flakes, parallel to each other, covering the surface of the alumina support, forming a continuous and dense film. Figure 4 The intensity of the (002) characteristic peak of graphite in the spectrum is stronger than that in Example 1, which proves that the graphite content in the carbon molecular sieve membrane prepared with HB pencil lead in Example 2 is higher than that in the carbon molecular sieve membrane prepared with 6H pencil lead in Example 1.

[0055] Example 3

[0056] The specific implementation steps are the same as in Example 1, except that the hardness grade of the pencil lead in step (2) is 2B.

[0057] Staedtler 2B pencil lead has the following composition: graphite: clay: wax = 64:26:10. (SEM) Figure 5 This indicates that the graphite is stacked in flakes, parallel to each other, covering the surface of the alumina support, forming a continuous and dense film with a thickness of approximately 2.02 μm. Figure 6 XRD( Figure 7 The intensity of the (002) characteristic peak of graphite in the spectrum is stronger than that in Example 2, which proves that the graphite content in the carbon molecular sieve membrane prepared with 2B pencil lead in Example 3 is higher than that in the carbon molecular sieve membrane prepared with HB pencil lead in Example 2.

[0058] Example 4

[0059] The specific implementation steps are the same as in Example 1, except that the hardness grade of the pencil lead in step (2) is 6B.

[0060] Staedtler 6B pencil lead has a composition of graphite: clay: wax = 69:19:12. (SEM) Figure 8 The XRD results show that the graphite is stacked in flakes, parallel to each other, covering the surface of the alumina support, forming a continuous and dense film. Figure 9 The intensity of the (002) characteristic peak of graphite in the spectrum is stronger than that in Example 3, which proves that the graphite content in the carbon molecular sieve membrane prepared with 6B pencil lead in Example 4 is higher than that in the carbon molecular sieve membrane prepared with 2B pencil lead in Example 3.

[0061] Example 5

[0062] The specific implementation steps are the same as in Example 1, except that the hardness grade of the pencil lead in step (2) is 10B.

[0063] Staedtler 10B pencil lead has a composition of graphite: clay: wax = 76:10:14. (SEM) Figure 10This indicates that the graphite is stacked in flakes and covers the surface of the alumina support in parallel, forming a continuous and dense film layer on the surface of the alumina support, with a film layer thickness of approximately 2.42 μm.

[0064] Example 6: Dye Retention Performance Test of Carbon Molecular Sieve Membranes Prepared by Mechanical Wiping Process

[0065] Dye rejection tests were performed on the carbon molecular sieve membranes prepared in Examples 1-5 sequentially: a dead-end filtration test apparatus was used, the dye used was a 100 mg / L Congo red solution, the operating pressure was 3 bar at room temperature, and the membrane area was 2.55 cm². 2 .

[0066] The test results are shown in Table 1. This demonstrates that different types of pencils exhibit excellent retention capacity for Congo red solutions, with differences in performance observed based on the content of their components (graphite, clay, and wax in the pencil lead). Among these, the carbon molecular sieve membrane prepared using Staedtler 2B pencil lead in Example 3 showed the best retention performance for Congo red.

[0067] Table 1: Congo Red Retention Performance Test of Carbon Molecular Sieve Membranes Prepared by Mechanical Wiping Process

[0068]

[0069] Example 7

[0070] The carbon molecular sieve membrane prepared in Example 3 was subjected to dye rejection tests: a dead-end filtration test apparatus was used, and the dyes used were Congo Red (CR), Methylene Blue (MB), and Brilliant Yellow (BY). The concentration of each dye solution was 100 mg / L. The operating pressure was 3 bar at room temperature, and the membrane area was 2.55 cm². 2 .

[0071] The test results are shown in Table 2. This demonstrates that the carbon molecular sieve membrane prepared in Example 3 exhibits excellent dye retention capabilities for Congo Red (CR), Methyl Blue (MB), and Brilliant Yellow (BY).

[0072] Table 2: Dye Retention Performance Tests of the Carbon Molecular Sieve Membranes Prepared in Example 3

[0073]

[0074] Example 8

[0075] The H2 / CO2 gas separation performance of the carbon molecular sieve membrane prepared in Example 3 was tested: at room temperature, the feed pressure on the permeate side was 1 bar, the H2 feed content was 0.5%, the purge gas was N2, and the membrane area was 2.55 cm². 2 According to the test results, the H2 permeation flux of the membrane is 1.43 × 10⁻⁶.-7 mol·m -2 ·s -1 ·Pa -1 Its separation factor is 5.5.

[0076] Example 9

[0077] The H2 / CH4 gas separation performance of the carbon molecular sieve membrane prepared in Example 3 was tested: at room temperature, the feed pressure on the permeate side was 1 bar, the H2 feed content was 0.5%, the purge gas was N2, and the membrane area was 2.55 cm². 2 According to the test results, the H2 permeation flux of the membrane is 1.68 × 10⁻⁶. -7 mol·m -2 ·s -1 ·Pa -1 Its separation factor is 4.3.

[0078] Example 10

[0079] The carbon molecular sieve membranes prepared in Examples 3-5 were subjected to alcohol-water separation tests in sequence: a pervaporation membrane cell was used, the feed solution used was 10 wt% ethanol / water solution, the experimental temperature was 60°C, and the membrane area was 2.55 cm². 2 The test results are shown in Table 1.

[0080] Table 3: Alcohol-water separation test of carbon molecular sieve membranes prepared by mechanical coating process

[0081]

[0082] The carbon molecular sieve membranes prepared in Examples 3-5 were subjected to alcohol-water separation tests in sequence: a pervaporation membrane cell was used, the feed solution used was 10 wt% ethanol / water solution, the experimental temperature was 70°C, and the membrane area was 2.55 cm². 2 The test results are shown in Table 1.

[0083] Table 4: Alcohol-water separation test of carbon molecular sieve membranes prepared by mechanical coating process

[0084]

[0085] Example 11

[0086] (1) Fix a tubular porous alumina carrier with a surface particle size of about 5 μm on a multi-functional lathe platform, cut one end of a Staedtler 2B pencil lead into a cylindrical pencil lead with a diameter of about 1.4 cm, and place it on the surface of the porous alumina carrier.

[0087] (2) The parameters of the multi-functional lathe are set as follows: rotation speed of 3000 rpm, spin coating time per unit area of ​​carrier of 15 s / cm.2 .

[0088] (3) Before spin coating, 1 ml of ethanol was dropped onto the surface of the porous alumina carrier. Then, while spin coating, the pencil lead was moved horizontally. This process was repeated twice to finally prepare a continuous and dense carbon molecular sieve membrane.

[0089] (4) Wash and dry the carbon molecular sieve membrane obtained in step (3), and manually scrape off the excess carbon powder on the surface.

[0090] Staedtler 2B pencil lead is composed of graphite: clay: wax = 64:26:10. (The rest of the text appears to be unrelated and likely refers to a different topic.) Figure 11 As shown, graphite is stacked in flake form, covering the surface of the alumina support, forming a continuous and dense film layer on the surface of the tubular alumina support. The dye retention performance of the above-mentioned carbon molecular sieve membrane was tested: a cross-flow filtration test device was used, the dye used was a 100 mg / L Congo red solution, the operating pressure was 1 bar at room temperature, and the membrane area was 6.03 cm². 2 The final test results showed that the carbon molecular sieve membrane exhibited a rejection rate of 92.61% for a 100 mg / L Congo red solution, with a flux of 35.28 L·m⁻¹. -2 ·h -1 ·bar -1 .

[0091] Example 12

[0092] (1) Fix a tubular porous alumina carrier with a surface particle size of about 5 μm on a multi-functional lathe platform, prepare an ethanol solution of 2 g / L PEI (polyethyleneimine, MW70000, 50% aqueous solution) and an ethanol solution of 1 g / L TA (tannic acid, 95%), cut one end of a Staedtler 2B pencil lead into a cylindrical pencil lead with a diameter of about 1.4 cm, and place it on the surface of the porous alumina carrier.

[0093] (2) The parameters of the multi-functional lathe are set as follows: rotation speed of 3000 rpm, spin coating time per unit area of ​​carrier of 15 s / cm. 2 .

[0094] (3) Before spin coating, 0.5 ml of PEI ethanol solution (2 g / L) was dropped onto the surface of the porous alumina support. After spin coating with a 2B pencil lead for 1 min, 0.5 ml of TA ethanol solution (1 g / L) was dropped onto the surface of the porous alumina support. Then spin coating with a 2B pencil lead for 1 min. This process was repeated twice to finally prepare a continuous and dense carbon molecular sieve membrane.

[0095] (4) Wash and dry the carbon molecular sieve membrane obtained in step (3), and manually scrape off the excess carbon powder on the surface.

[0096] Staedtler 2B pencil lead is composed of graphite: clay: wax = 64:26:10. (The rest of the text appears to be unrelated and likely refers to a different topic.) Figure 12 As shown, graphite is stacked in flake form, covering the surface of the alumina support, forming a continuous and dense film layer on the surface of the tubular alumina support. The dye retention performance of the above-mentioned carbon molecular sieve membrane was tested: a cross-flow filtration test device was used, the dye used was a 100 mg / L Congo red solution, the operating pressure was 1 bar at room temperature, and the membrane area was 6.03 cm². 2 The final test results showed that the carbon molecular sieve membrane exhibited a retention rate of 99.4% for a 100 mg / L Congo red solution, with a flux of 21.91 L·m⁻¹. -2 ·h -1 ·bar -1 .

[0097] Comparative Example 1

[0098] The specific implementation steps are the same as in Example 3, except that the porous carrier surface in step (1) is a disc-shaped porous alumina carrier with a particle size of about 70 nm.

[0099] SEM Figure 13 The image shows a SEM image of a blank alumina support. Figure 14 This indicates that alumina supports with a surface particle size of approximately 70 nm cannot be used to form continuous and dense carbon molecular sieve membranes. This demonstrates that the mechanical wiping coating process requires a certain degree of surface roughness on the support.

[0100] Comparative Example 2

[0101] The specific implementation steps are the same as in Example 3, except that the solvent used in step (3) for wetting is water. SEM ( Figure 15 This indicates that using water as a solvent in the wetting process cannot produce a continuous and dense carbon molecular sieve membrane.

[0102] Comparative Example 3

[0103] The specific implementation steps are the same as in Example 3, except that the wiping method in step (3) is manual wiping. SEM ( Figure 16 This indicates that manual wiping cannot be used to prepare a continuous and dense carbon molecular sieve membrane.

[0104] Comparative Example 4

[0105] The specific implementation steps are the same as in Example 3, except that there is no wetting process in step (3). SEM ( Figure 17 This indicates that dry friction coating cannot be used to prepare continuous and dense carbon molecular sieve membranes.

[0106] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the invention.

[0107] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for preparing carbon molecular sieve membranes using a mechanical coating process, characterized in that: Includes the following steps: (1) Fix a porous carrier whose surface has been wetted with an organic solvent, and place a cylindrical pen refill on the surface of the porous carrier; the particle size of the porous carrier surface is greater than or equal to 2 μm; (2) Use an automatic wiping device to perform wiping. During the spin coating process, move the pen tip horizontally to ensure that it can be evenly wiped onto the porous carrier surface. After repeated wiping, a continuous and dense carbon molecular sieve membrane is finally prepared.

2. The method for preparing carbon molecular sieve membranes using a mechanical coating process as described in claim 1, characterized in that: It also includes washing and drying the carbon molecular sieve membrane obtained in step (2).

3. The method for preparing carbon molecular sieve membranes using a mechanical coating process as described in claim 1, characterized in that: The porous carrier mentioned in step (1) includes porous metal oxides, porous glass, porous non-metal oxides, porous metals or porous polymers; the structure of the porous carrier includes a disc structure, a flat plate structure, a tubular structure or a spiral structure; the particle size on the surface of the porous carrier is 2μm to 100μm.

4. The method for preparing carbon molecular sieve membranes using a mechanical coating process as described in claim 1, characterized in that: The organic solvent in step (1) includes one or more of the following: low carbon alcohols, low carbon organic acids, low carbon esters, low carbon ketones and low carbon amides.

5. The method for preparing carbon molecular sieve membranes using a mechanical coating process as described in claim 1, characterized in that: In step (1), the organic solvent is a low-carbon alcohol solution of a crosslinking agent, wherein the types of crosslinking agents include: a mixture of polyethyleneimine and tannic acid, polyvinyl alcohol, polyvinyl butyral or polyethyleneimine.

6. The method for preparing carbon molecular sieve membranes using a mechanical coating process as described in claim 1, characterized in that: The lead mentioned in step (1) includes graphite lead, pencil lead or charcoal lead.

7. The method for preparing carbon molecular sieve membranes using a mechanical coating process as described in claim 1, characterized in that: The contact area between the cylindrical pen tip and the carrier surface in step (1) is 0.01–100 mm². 2 .

8. The method for preparing carbon molecular sieve membranes using a mechanical coating process as described in claim 1, characterized in that: In step (2), the spin coating speed is 500 to 5000 rpm.

9. The method for preparing carbon molecular sieve membranes using a mechanical coating process as described in claim 1, characterized in that: In step (2), the spin coating time per unit area of ​​the carrier is 10–750 s / cm. 2 .

10. The application of a carbon molecular sieve membrane obtained by the method of claim 1 in gas separation, dye retention or alcohol-water separation.

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