A method for preparing a uniform, dense, alcohol-prioritized composite membrane

Abstract

The application relates to a preparation method of a uniform and dense priority alcohol-permeable composite membrane, and belongs to the field of membrane separation and technology. The method comprises the following steps: adding a catalyst A containing a copper ion compound, a graphdiyne synthesis monomer and an organic polymer into ethanol, mixing and reacting under certain conditions to prepare a graphdiyne / organic polymer membrane liquid A, and loading the membrane liquid A on a base film through a certain method. A polymer crosslinking agent and a catalyst B are mixed in a certain proportion to prepare a membrane liquid B. The membrane liquid B is heated to make the crosslinking agent vapor fill the container, the graphdiyne / organic film loaded on the base film is placed in the container, the reaction between the organic and the crosslinking agent occurs on the surface of the film, and after the reaction is completed, the film is placed in an environment at 80 DEG C to sufficiently perform a thermal crosslinking reaction. The obtained separation layer is higher in compactness and smaller in thickness, no solvent is used in the gas-solid / gas-liquid interface reaction process, the membrane is more uniform and dense, has higher pervaporation alcohol-permeable performance, and can efficiently and stably recover ethanol.

Description

Technical Field

[0001] This invention belongs to the field of membrane separation and technology, specifically relating to a uniform and dense preferential alcohol permeation composite membrane and its preparation method. Technical Background

[0002] In the production of bioethanol, the low concentration of the fermentation broth leads to high ethanol separation costs. Membrane-based pervaporation technology offers advantages such as low energy consumption, high selectivity, and mild operating conditions, allowing for efficient separation when coupled with the fermentation process. During the fermentation-coupling process, it is crucial to promptly remove the ethanol produced during fermentation to minimize its toxicity to microorganisms and ensure rapid, continuous production. Therefore, the core of pervaporation lies in the selection and preparation of the membrane material. A preferred pervaporation composite membrane, prepared by doping graphylene into organic polymers, combines the advantages of high permeability, high selectivity, and high stability of graphylene with the ease of processing organic materials. Applying this membrane to the pervaporation process can effectively improve the ethanol recovery rate.

[0003] Traditional methods for preparing alcohol-preferential pervaporation membranes, such as coating and impregnation, involve solvent evaporation, leading to insufficient contact between the organic polymer and crosslinking agent, resulting in uneven film formation and poor density. Furthermore, traditional methods use high-viscosity organic polymers as the crosslinking substrate to obtain a dense separation layer for alcohol preferential pervaporation. Therefore, large amounts of toxic organic solvents (such as n-heptane, n-hexane, toluene, and dimethylformamide) are needed to dissolve the polymers and reduce their viscosity for film formation. The evaporation of these organic solvents into the air during membrane formation pollutes the environment. In the preparation of traditional composite membranes, the incompatibility between nanoparticles and polymers can easily lead to uneven nanoparticle distribution and particle aggregation, thus affecting the separation performance of the composite membrane.

[0004] Gas-solid / gas-liquid interfacial reactions involve heating a substance capable of cross-linking with organic polymers into a gas phase. A membrane loaded with graphyne and the organic polymer is then placed in this gas phase environment. Cross-linking reactions occur on the membrane surface between the gas-phase cross-linking agent and the solid / liquid organic matter, resulting in a dense separation membrane. In this process, the absence of solvents allows for ample contact between the gas-phase cross-linking agent and the organic polymer, resulting in a larger, more uniform reaction area and a more complete reaction, leading to a denser membrane. Due to the more complete cross-linking, a thinner separation layer can achieve high selectivity, reducing the thickness of the composite membrane and improving permeability. In summary, gas-solid / gas-liquid interfacial reactions can yield composite membranes with high selectivity and high permeability. The dense membrane formation process can produce high-performance, defect-free pervaporation membranes for the rapid and efficient separation of ethanol from aqueous solutions, further promoting the industrial application of pervaporation-preferential ethanol-to-ethanol composite membranes, which have significant value in alcohol-water separation. Summary of the Invention

[0005] The key technical problem to be solved by this invention is to provide a method for preparing a uniform and dense preferential alcohol permeation composite membrane, thereby further improving the performance of the preferential alcohol permeation membrane in ethanol recovery. The specific technical solution is as follows:

[0006] A method for preparing a uniform, dense, preferentially permeable alcohol composite membrane includes the following steps:

[0007] Step a: Add catalyst A containing copper ions to ethanol and mix thoroughly. Then add the monomer and organic polymer corresponding to the synthesis of graphyne, stir for 0.5-2 hours, sonicate for 0.1-2 hours, and then heat in an oven at 50-150℃ for 2-10 hours to prepare graphyne / organic polymer membrane solution A. Load the porous base membrane with membrane solution A using a certain method, and then let the solvent evaporate in the air.

[0008] Step b: Mix the silicon-based crosslinking agent and catalyst B in a certain proportion until homogeneous, stir for 0.1-2 hours, and prepare film solution B;

[0009] Step c: Place a certain amount of membrane solution B at the bottom of a container, heat to 40-100℃ to fill the container with crosslinking agent vapor, place the porous base membrane loaded with graphyne / organic material in step a into the vapor in the container, and a gas-solid or / and gas-liquid reaction of organic material and crosslinking agent will occur on the membrane surface for 3-8 hours; then remove the membrane and place it in an 80℃ environment for 0.5-8 hours for further thermal crosslinking reaction.

[0010] Specifically, the graphyne described in step a is one or more of graphdiyne (GDY). Preferably, the monomers corresponding to the synthesis of the above-mentioned graphyne are one or more of 1,3,5-triethynylbenzene (TEB), tris(4-ethynylphenyl)amine (TEPA), 1,3,5-tris-(4-ethynylphenyl)benzene (Ext-TEB), or hexaethynylbenzene (HEB) containing terminal alkynes; catalyst A is one or more of copper hydroxide (Cu(OH)2) or copper acetate (Cu(CH3COO)2). The organic polymer is one or more of polydimethylsiloxane (PDMS), polyphenylmethylsiloxane (PPMS), polytrifluoropropylmethylsiloxane (PTFMS), or polytrimethylsiloxypyridine (PTMSP).

[0011] Specifically, the porous base membrane in step a is an organic polymer membrane, an inorganic membrane, or an organic / inorganic hybrid membrane, with an average pore size of 10-100 nm; the porous base membrane is in the form of a flat plate, a tubular membrane, or a hollow fiber membrane.

[0012] Specifically, in step a, the content of organic polymer in membrane solution A is 5wt%-80wt%; the content of graphyne synthesis monomer is 0.1wt%-20wt%. The concentration of catalyst A added to ethanol solution is 0.1-5g / L.

[0013] Preferably, the method for loading the porous base membrane with membrane liquid A in step a is one or more of the following: impregnation, vacuum filtration, spraying, spin coating, and blade coating.

[0014] Specifically, the crosslinking agent in step b is one or more of tetraethyl orthosilicate (TEOS), propyl orthosilicate (TPOS), butyl orthosilicate (TBOS), vinyltriethoxysilane (VTES), ethyltriethoxysilane (ETES), or trifluoropropyltriethoxysilane (TFPTES); and the catalyst is one or more of dibutyltin dilaurate (DBTDL), monobutyltin oxide (MBTO), dibutyltin oxide (DBTO), tripropyltin oxide (TPTO), or chloroplatinic acid.

[0015] Preferably, the crosslinking agent content in the membrane solution in step b is 80wt%-99wt%, and the catalyst B content is 1wt%-20wt%.

[0016] This invention relates to the application of a uniform and dense preferential alcohol permeation composite membrane, which separates ethanol from an aqueous solution through pervaporation.

[0017] The beneficial effects of the technical solution provided by this invention are as follows: This invention employs a gas-solid / gas-liquid interfacial reaction method to achieve polymer crosslinking and film formation, resulting in a more uniform and complete film formation. Ethanol is recovered from the alcohol-water mixture via pervaporation. The film formation method used in this invention effectively increases the contact area between the crosslinking agent and the organic polymer, and the gas-phase crosslinking agent can more fully and uniformly contact and react with the organic polymer. The crosslinking density of the film prepared by the gas-solid / gas-liquid interfacial reaction in this invention is 21.3 × 10⁻⁶. -4 mol cm -3 The crosslinking density of the membrane is greater than that prepared by traditional methods. Figure 1 This invention enables tighter cross-linking of the polymer in the effective separation layer, resulting in stronger membrane adhesion and improved membrane separation performance. The membrane with an effective separation layer thickness of 1-3 μm prepared by this invention represents a reduction of over 70% compared to traditional membrane fabrication methods. Figure 2 This invention effectively enhances permeability, with the membrane's permeation flux being 2-3 times that of traditional composite membranes. Furthermore, the method of this invention does not use toxic solvents, and the resulting membrane is dense and uniform, laying the foundation for the efficient separation of alcohol-water mixtures using a priority permeation composite membrane. Attached Figure Description

[0018] Figure 1Example 1 of this invention: a comparison of the crosslinking density of a pure PDMS membrane prepared by the gas-solid interface reaction method and a pure PDMS membrane prepared by the conventional method.

[0019] Figure 2 Example 1 of this invention describes a pure PDMS membrane prepared using a gas-solid interface reaction method. Figure 2-1 ) and pure PDMS membranes prepared by traditional methods ( Figure 2-2 Thickness comparison diagram obtained from EDS line scan energy spectrum.

[0020] Figure 3 Scanning electron microscope (SEM) images of the (3-1) surface and (3-2) cross section of the TNP-GDY / PDMS composite membrane prepared in Example 2 of this invention.

[0021] Figure 4 Scanning electron microscope (SEM) images of the (4-1) surface and (4-2) cross section of the TNP-GDY / PDMS composite membrane prepared in Example 4 of this invention.

[0022] Figure 5 Scanning electron microscope (SEM) images of the surface (5-1) and cross-section (5-2) of the HsGDY / PDMS composite membrane prepared in Example 5 of this invention. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. However, the present invention is not limited to the following embodiments. Crosslinking density was measured using a VTMR20-010V-I nuclear magnetic resonance crosslinking density imaging analyzer. Surface and cross-sectional images were observed and measured using a ZEISS Sigma 300 scanning electron microscope (SEM). The film thickness was determined using Xplore energy-dispersive X-ray spectroscopy (EDS) for corresponding elemental analysis.

[0024] This invention provides a method for preparing a uniform, dense, preferentially permeable alcohol composite membrane, comprising the following steps:

[0025] Step 101: Add catalyst A containing copper ions to ethanol to prepare a 0.5 g / L solution. Then add the monomer corresponding to the synthesized graphyne and the organic polymer to the solution, stir for 1 h, sonicate for 0.5 h, and then heat in an oven at 60-120℃ for 2-10 h to prepare graphyne / organic polymer membrane solution A. Load the porous base membrane with membrane solution A using a certain method, and then allow the solvent to evaporate in air for 2 h.

[0026] Step 102: Mix the silicon-based crosslinking agent and catalyst B in a certain proportion until homogeneous, stir for 0.5 h, and prepare the film solution B.

[0027] Step 103: Place a certain amount of membrane solution B at the bottom of a container, heat to 40-80℃ to fill the container with crosslinking agent vapor, and place the porous base membrane loaded with graphyne / organic material from step 101 into the container. The organic material and crosslinking agent will react on the membrane surface for 3-8 hours. Afterward, place the membrane in an 80℃ environment for 0.5-8 hours for further thermal crosslinking reaction.

[0028] Specifically, the graphyne mentioned in step 101 is one or more of graphdiyne (GDY). The graphyne monomer is one or more of 1,3,5-triethynylbenzene (TEB), tris(4-ethynylphenyl)amine (TEPA), 1,3,5-tris-(4-ethynylphenyl)benzene (Ext-TEB), or hexaethynylbenzene (HEB) containing terminal alkynes; catalyst A is one or more of copper hydroxide (Cu(OH)2) or copper acetate (Cu(CH3COO)2). The organic polymer is one or more of polydimethylsiloxane (PDMS), polyphenylmethylsiloxane (PPMS), polytrifluoropropylmethylsiloxane (PTFMS), or polytrimethylsiloxypyridine (PTMSP).

[0029] Specifically, the porous base membrane mentioned in step 101 is an organic polymer membrane, an inorganic membrane, or an organic / inorganic hybrid membrane, with an average pore size of 10-100 nm; the porous base membrane is in the shape of a flat plate, a tubular membrane, or a hollow fiber membrane.

[0030] Specifically, the content of organic polymer in membrane solution A in step 101 can be 5wt%, 10wt%, 20wt%, 30wt%, 40wt%, or 50wt%; the content of graphyne synthesis monomer can be 0.5wt%, 1wt%, 2wt%, 3wt%, or 4wt%; and the concentration of catalyst A added to ethanol can be 0.1g / L, 0.5g / L, 1g / L, 3g / L, or 5g / L.

[0031] Preferably, the method for loading the porous base membrane with membrane liquid A in step 101 is one or more of the following: impregnation, vacuum filtration, spraying, spin coating, and blade coating.

[0032] Specifically, the crosslinking agent in step 102 is one or more of tetraethyl orthosilicate (TEOS), propyl orthosilicate (TPOS), butyl orthosilicate (TBOS), vinyltriethoxysilane (VTES), ethyltriethoxysilane (ETES), or trifluoropropyltriethoxysilane (TFPTES); and the catalyst B is one or more of dibutyltin dilaurate (DBTDL), monobutyltin oxide (MBTO), dibutyltin oxide (DBTO), tripropyltin oxide (TPTO), or chloroplatinic acid.

[0033] Preferably, the content of crosslinking agent in the membrane solution in step 102 can be 80wt%, 85wt%, 90wt%, or 95wt%, and the content of catalyst B can be 5wt%, 10wt%, 15wt%, or 20wt%.

[0034] Preferably, the vaporization heating temperature of the crosslinking agent in step 103 can be 40℃, 50℃, 60℃, 70℃, or 80℃; the crosslinking reaction time of the organic matter and the crosslinking agent can be 2h, 4h, 6h, 8h, or 10h; and the thermal crosslinking reaction time can be 2h, 4h, 6h, 8h, or 10h.

[0035] The present invention will be further described below through specific embodiments.

[0036] In the following specific embodiments, operations without specified conditions are performed under standard conditions or conditions recommended by the manufacturer. Raw materials without specified manufacturers and specifications are all commercially available products.

[0037] Example 1 (Comparative Example)

[0038] This example is a comparative experiment using pure polymer membranes.

[0039] Polysulfone (PSf) planar ultrafiltration membrane was used as the porous base membrane with a molecular weight cutoff of 20,000. The selected organic polymer was polydimethylsiloxane (PDMS), the selected crosslinking agent was tetraethyl orthosilicate (TEOS), and the selected catalyst B was dibutyltin dilaurate (DBTDL).

[0040] The gas-solid interface reaction film formation process involves adding PDMS to an ethanol solution and stirring at room temperature for 30 min to prepare a PDMS solution with a PDMS content of 20 wt%. This solution is then dropped onto the surface of a polysulfone-based membrane. After the solvent evaporates, the membrane is placed in a TEOS vapor environment at 50 °C (TEOS:DBTDL mass ratio of 8:1) for 6 h, followed by a crosslinking reaction in a vacuum drying oven at 80 °C for 8 h. This yields a uniform and dense pure PDMS membrane that preferentially permeates through ethanol.

[0041] The traditional film-forming method involves adding PDMS, TEOS, and DBTDL to ethanol at a mass ratio of 8:1.2:0.15, stirring at room temperature for 30 min to prepare a PDMS crosslinking solution with a PDMS content of 20 wt%. This solution is then dropped onto the surface of a polysulfone-based membrane. After the solvent evaporates, the membrane is placed in an 80°C vacuum drying oven for a crosslinking reaction for 8 h. This yields a pure PDMS membrane that preferentially permeates through alcohol.

[0042] Figure 1The results show that the crosslinking density of the pure PDMS film prepared by the gas-solid interface reaction method in this example is greater than that of the film prepared by the traditional method, indicating that the gas-solid interface reaction method can produce a more uniform and dense film. (EDS line scan results) Figure 2 The results show that the membrane thickness prepared by the gas-solid interface reaction method is 2.5 μm, which is smaller than that of the membrane prepared by the traditional method (10 μm). This indicates that the gas-solid interface reaction method can reduce the thickness of the separation layer and thus increase the membrane permeability.

[0043] The prepared PDMS membrane was placed in a pervaporation device for performance testing. The test conditions were: (1) the raw material liquid was 5wt% ethanol aqueous solution and the feed temperature was 60℃; (2) the downstream pressure of the membrane was 200Pa.

[0044] The pervaporation performance of the pure PDMS membrane prepared by the gas-solid interface reaction method was measured to be: a permeation flux of 3168.8 gm³. -2 h -1 The separation factor was 8.8, and the ethanol content in the permeate was 30 wt%. The pervaporation performance of the pure PDMS membrane prepared by the conventional method was measured to be: permeation flux of 1129.9 gm³. -2 h -1 The separation factor was 8.8, and the ethanol content in the permeate was 30 wt%.

[0045] Example 2

[0046] Polysulfone (PSf) planar ultrafiltration membrane was used as the porous base membrane with a molecular weight cutoff of 20,000. The selected graphdiyne monomer was tris(4-ethynylphenyl)amine (TEPA). Catalyst A was copper acetate, which was dissolved in ethanol to prepare a 0.5 g / L solution. The selected organic polymer was polydimethylsiloxane (PDMS), the selected crosslinking agent was tetraethyl orthosilicate (TEOS), the selected catalyst B was dibutyltin dilaurate (DBTDL), and the selected organic solvent was ethanol.

[0047] Step a: Dissolve the monomers tris(4-ethynylphenyl)amine (TEPA) and polydimethylsiloxane (PDMS) in a 0.5 g / L copper acetate ethanol solution (mass ratio 0.1:4:15.9), mix thoroughly, wherein the content of TEPA is 0.5 wt% and the content of polymer PDMS is 20 wt%. Stir for 1 h, sonicate for 0.5 h, and then heat in a 60 °C oven for 6 h to prepare TNP-GDY / PDMS membrane solution A. Immerse the polysulfone-based membrane in membrane solution A for 30 s, with one impregnation layer. Then allow the solvent to evaporate in air for 2 h. At this point, only PDMS and TNP-GDY remain on the membrane, with the content of TNP-GDY being 2.5 wt%.

[0048] Step b: Mix the crosslinking agent tetraethyl orthosilicate (TEOS) and catalyst B dibutyltin dilaurate (DBTDL) at a mass ratio of 8:1, stir for 0.5 h, and prepare film solution B.

[0049] Step c: Place a certain amount of membrane solution B at the bottom of a container, heat to 50°C to fill the container with TEOS vapor, and place the membrane loaded with TNP-GDY / PDMS from step a into the container. A reaction between organic matter and crosslinking agent occurs on the membrane surface for 6 hours. Afterward, place the membrane in an 80°C environment for 2 hours for thermal crosslinking to obtain a TNP-GDY / PDMS preferential alcohol pervaporation membrane.

[0050] SEM results ( Figure 3-1 The results show that the graphylene loading on the surface of the prepared composite film is uniform. Figure 3-2 The selective separation layer of the prepared composite membrane is shown to be 1 μm thick.

[0051] The prepared composite membrane was placed in a pervaporation device for performance testing. The test conditions were: (1) the raw material liquid was 5wt% ethanol aqueous solution and the feed temperature was 60℃; (2) the downstream pressure of the membrane was 200Pa.

[0052] The measured pervaporation performance of the composite membrane was: a permeation flux of 2196.2 gm³. -2 h -1 The separation factor was 11.3, and the ethanol content in the permeate was 35 wt%.

[0053] Example 3

[0054] Step a: Dissolve the monomers tris(4-ethynylphenyl)amine (TEPA) and polydimethylsiloxane (PDMS) in a 0.5 g / L copper acetate ethanol solution (mass ratio 0.1:4:15.9) and mix thoroughly. The content of TEPA is 0.5 wt%, and the content of PDMS polymer is 20 wt%. Stir for 1 h, sonicate for 0.5 h, and then heat in a 60 °C oven for 6 h to prepare TNP-GDY / PDMS membrane solution A. Immerse the polysulfone-based membrane in membrane solution A for 30 s, with one impregnation layer. Then allow the solvent to evaporate in air for 2 h. At this point, only PDMS and TNP-GDY remain on the membrane, with the content of TNP-GDY being 2.5 wt%.

[0055] Step b: Mix the crosslinking agent tetraethyl orthosilicate (TEOS) and catalyst B dibutyltin dilaurate (DBTDL) at a mass ratio of 8:1, stir for 0.5 h, and prepare film solution B.

[0056] Step c: Place a certain amount of membrane solution B at the bottom of a container, heat to 50°C to fill the container with TEOS vapor, and place the membrane loaded with TNP-GDY / PDMS from step a into the container. A reaction between organic matter and crosslinking agent occurs on the membrane surface for 4 hours. Afterward, place the membrane in an 80°C environment for 2 hours for thermal crosslinking reaction to obtain the TNP-GDY / PDMS preferential alcohol pervaporation membrane.

[0057] The prepared composite membrane was placed in a pervaporation device for performance testing. The test conditions were: (1) the raw material liquid was 5wt% ethanol aqueous solution and the feed temperature was 60℃; (2) the downstream pressure of the membrane was 200Pa.

[0058] The measured pervaporation performance of the composite membrane was: a permeation flux of 1898.1 gm³. -2 h -1 The separation factor was 10.7, and the ethanol content in the permeate was 34 wt%.

[0059] Example 4

[0060] Step a: Dissolve the monomers tris(4-ethynylphenyl)amine (TEPA) and polydimethylsiloxane (PDMS) in a 0.5 g / L copper acetate ethanol solution (mass ratio 0.1:4:15.9) and mix thoroughly. The content of TEPA is 0.5 wt%, and the content of PDMS polymer is 20 wt%. Stir for 1 h, sonicate for 0.5 h, and then heat in a 60 °C oven for 6 h to prepare TNP-GDY / PDMS membrane solution A. Load membrane solution A onto a polysulfone-based membrane by vacuum filtration, and then allow the solvent to evaporate in air for 2 h. At this point, the membrane contains only PDMS and TNP-GDY, with a TNP-GDY content of 2.5 wt%.

[0061] Step b: Mix the crosslinking agent tetraethyl orthosilicate (TEOS) and catalyst B dibutyltin dilaurate (DBTDL) at a mass ratio of 8:1, stir for 0.5 h, and prepare film solution B.

[0062] Step c: Place a certain amount of membrane solution B at the bottom of a container, heat to 50°C to fill the container with TEOS vapor, and place the membrane loaded with TNP-GDY / PDMS from step a into the container. A reaction between organic matter and crosslinking agent occurs on the membrane surface for 6 hours. Afterward, place the membrane in an 80°C environment for 2 hours for thermal crosslinking to obtain a TNP-GDY / PDMS preferential alcohol pervaporation membrane.

[0063] SEM results ( Figure 4-1 The results show that the graphylene loading on the surface of the prepared composite film is uniform. Figure 4-2 The selective separation layer thickness of the prepared composite membrane is shown to be 2.5 μm.

[0064] The prepared composite membrane was placed in a pervaporation device for performance testing. The test conditions were: (1) the raw material liquid was 5wt% ethanol aqueous solution and the feed temperature was 60℃; (2) the downstream pressure of the membrane was 200Pa.

[0065] The measured pervaporation performance of the composite membrane was: a permeation flux of 4291.7 gm³. -2 h -1 The separation factor was 9.0, and the ethanol content in the permeate was 30 wt%.

[0066] Example 5

[0067] Polysulfone (PSf) planar ultrafiltration membrane was used as the porous base membrane with a molecular weight cutoff of 20,000. The selected graphdiyne monomer was 1,3,5-triethynylbenzene (TEB). The catalyst A was copper acetate, which was dissolved in ethanol to prepare a 0.5 g / L solution. The selected organic polymer was polydimethylsiloxane (PDMS), the selected crosslinking agent was tetraethyl orthosilicate (TEOS), and the selected catalyst B was dibutyltin dilaurate (DBTDL).

[0068] Step a: Dissolve monomer 1,3,5-triethynylbenzene (TEB) and polydimethylsiloxane (PDMS) in a 0.5 g / L copper acetate ethanol solution (mass ratio 0.1:4:15.9) and mix thoroughly. The content of TEB is 0.5 wt%, and the content of polymer PDMS is 20 wt%. Stir for 1 h, sonicate for 0.5 h, and then heat in a 60 °C oven for 6 h to prepare HsGDY / PDMS membrane solution A. Load membrane solution A onto a polysulfone-based membrane by vacuum filtration, and then allow the solvent to evaporate in air for 2 h. At this point, the membrane contains only PDMS and HsGDY, with the content of HsGDY being 2.5 wt%.

[0069] Step b: Mix the crosslinking agent tetraethyl orthosilicate (TEOS) and catalyst B dibutyltin dilaurate (DBTDL) at a mass ratio of 8:1, stir for 0.5 h, and prepare film solution B.

[0070] Step c: Place a certain amount of membrane solution B at the bottom of a container, heat to 50°C to fill the container with TEOS vapor, and place the membrane loaded with HsGDY / PDMS from step a into the container. A reaction between organic matter and crosslinking agent occurs on the membrane surface for 6 hours. Then, place the membrane in an 80°C environment for 8 hours for thermal crosslinking to obtain the HsGDY / PDMS preferential alcohol pervaporation membrane.

[0071] SEM results ( Figure 5-1 The results show that the graphylene loading on the surface of the prepared composite film is uniform. Figure 5-2The selective separation layer of the prepared composite membrane is shown to be 3 μm thick.

[0072] The prepared composite membrane was placed in a pervaporation device for performance testing. The test conditions were: (1) the raw material liquid was 5wt% ethanol aqueous solution and the feed temperature was 60℃; (2) the downstream pressure of the membrane was 200Pa.

[0073] The measured pervaporation performance of the composite membrane was: a permeation flux of 3472.5 gm³. -2 h -1 The separation factor was 11.7, and the ethanol content in the permeate was 38 wt%.

[0074] The above description is only a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a uniform, dense, preferentially permeable alcohol composite membrane, characterized in that, Includes the following steps: Step a: Add catalyst A containing copper ions to ethanol and mix thoroughly. Then add the monomer and organic polymer corresponding to the synthesis of graphyne, stir for 0.5-2 h, sonicate for 0.1-2 h, and then heat in an oven at 50-150 ℃ for 2-10 h to prepare graphyne / organic polymer membrane solution A. Load the porous base membrane with membrane solution A using a certain method, and then let the solvent evaporate in the air. Step b: Mix the silicon-based crosslinking agent and catalyst B in a certain proportion until homogeneous, stir for 0.1-2 h, and prepare film solution B; Step c: Place a certain amount of membrane solution B at the bottom of a container, heat to 40-100 ℃ to fill the container with crosslinking agent vapor, place the porous base membrane loaded with graphyne / organic material in step a into the vapor in the container, and a gas-solid or / and gas-liquid reaction of organic material and crosslinking agent will occur on the membrane surface for 3-8 h; then remove the membrane and place it in an 80 ℃ environment for 0.5-8 h for further thermal crosslinking reaction; The organic polymer is one or more of polydimethylsiloxane (PDMS), polyphenylmethylsiloxane (PPMS), polytrifluoropropylmethylsiloxane (PTFMS), or polytrimethylsiloxypyridine (PTMSP).

2. The method according to claim 1, characterized in that, The graphyne mentioned in step a is one or more of graphdiyne (GDY); the monomer corresponding to the synthesis of the above-mentioned graphyne is one or more of 1,3,5-triethynylbenzene (TEB), tris(4-ethynylphenyl)amine (TEPA), 1,3,5-tris-(4-ethynylphenyl)benzene (Ext-TEB) or hexaethynylbenzene (HEB) containing terminal alkynes; catalyst A is one or more of copper hydroxide (Cu(OH)2) or copper acetate (Cu(CH3COO)2).

3. The method according to claim 1, characterized in that, The porous base membrane mentioned in step a is an organic polymer membrane, an inorganic membrane, or an organic / inorganic hybrid membrane, with an average pore size of 10-100 nm, and a shape of flat plate, tubular, or hollow fiber.

4. The method according to claim 1, characterized in that, In step a, the content of organic polymer in membrane solution A is 5wt%-80wt%; the content of graphyne synthesis monomer is 0.1wt%-20wt%; and the concentration of catalyst A added to ethanol solution is 0.1-5g / L.

5. The method according to claim 1, characterized in that, The method for loading membrane liquid A onto the porous base membrane in step a is one or more of the following: impregnation, vacuum filtration, spraying, spin coating, and blade coating.

6. The method according to claim 1, characterized in that, The crosslinking agent mentioned in step b is one or more of tetraethyl orthosilicate (TEOS), propyl orthosilicate (TPOS), butyl silicate (TBOS), vinyltriethoxysilane (VTES), ethyltriethoxysilane (ETES), or trifluoropropyltriethoxysilane (TFPTES); the catalyst B is one or more of dibutyltin dilaurate (DBTDL), monobutyltin oxide (MBTO), dibutyltin oxide (DBTO), tripropyltin oxide (TPTO), or chloroplatinic acid.

7. The method according to claim 1, characterized in that, The crosslinking agent content in the membrane solution described in step b is 80wt%-99wt%, and the catalyst B content is 1wt%-20wt%.

8. A uniform, dense, preferentially permeable alcohol composite membrane prepared according to any one of claims 1-7.

9. The application of the uniform and dense preferential alcohol permeation composite membrane according to claim 8, wherein ethanol is separated from aqueous solution by pervaporation.

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