Disc type molecular sieve membrane with stability and high flux as well as preparation method and application of disc type molecular sieve membrane

Abstract

The invention provides a stable and high-flux disc type molecular sieve membrane as well as a preparation method and application thereof, and belongs to the technical field of molecular sieve membranes. According to the invention, the seed crystal suspension containing the organic modifier is coated on the surface of the butterfly ceramic carrier by a one-step method, and meanwhile, the effect of strengthening the binding force of the seed crystal layer and the carrier and the effect of improving the coating effect of the seed crystal layer of the molecular sieve are achieved. And further coating molecular sieve gel synthetic liquid on the surface of the carrier coated with the seed crystal layer to form a gel layer. And finally, putting into a reaction kettle for crystallization treatment to obtain the stable and high-flux butterfly type molecular sieve membrane. The butterfly molecular sieve membrane shows high permeation flux and rejection rate in organic solvent dehydration, and is suitable for industrial organic solvent dehydration.

Description

Technical Field

[0001] The invention belongs to the technical field of molecular sieve membranes, and in particular relates to a disc-type molecular sieve membrane with stable high flux and a preparation method and application thereof. Background Art

[0002] As a new type of membrane separation material, molecular sieve membrane has inherent characteristics such as excellent chemical stability, regular pore structure and adjustable silicon-aluminum ratio. Compared with traditional separation technologies such as distillation and adsorption, molecular sieve membrane pervaporation separation technology is suitable for constant boiling, near boiling and azeotropic mixture systems, and is not limited by the vapor-liquid equilibrium of the separation system. It has the advantages of high selectivity, simple operation and environmental friendliness. Therefore, molecular sieve membrane can greatly reduce the energy consumption and separation cost in the separation process, and has broad application prospects in the dehydration of organic solvents.

[0003] Ceramic supports are the basis and core materials for the preparation and application of molecular sieve membranes. They not only determine the factors related to membrane quality, such as the thickness, defects, and interface bonding strength of the molecular sieve membrane layer, but also affect the service life, cost, and operation and maintenance of the molecular sieve membrane. At present, the commonly used molecular sieve membrane supports on the market are tubular in shape, and the synthesized membranes have shortcomings such as small synthesis area, large permeation resistance, and high cost. At the same time, membrane fouling is the main problem restricting the efficient application of membrane separation technology. Although the problem of membrane fouling can be effectively addressed by measures such as increasing the hydraulic shear on the membrane surface or reducing the transmembrane pressure difference (TMP), for tubular ceramic membranes, increasing the membrane surface flow rate will inevitably cause an increase in TPM, which will cause serious membrane fouling problems; and lower TMP will cause a decrease in filtration efficiency. Therefore, how to solve the contradiction between high membrane surface flow rate and high TMP, achieve shear strengthening on the membrane surface, effectively reduce membrane fouling, and efficiently treat different feed liquid systems is a key issue that needs to be solved urgently.

[0004] The disc-shaped ceramic membrane has a disc-shaped appearance, and is designed with multiple spiral channels inside for the collection and outflow of the permeate. The separation layer is coated on the outer surface of the ceramic membrane. The small molecule feed liquid passes through the separation layer of the ceramic membrane into the spiral channel, and the permeate is collected and flows out at the hollow central axis. Through the high-speed rotation of the disc-shaped ceramic membrane, a high fluid velocity is generated on the membrane surface, thereby generating a strong shearing effect, forming a dynamic membrane filtration. During the filtration process, the membrane speed and TMP are controlled separately, which can achieve high membrane surface flow rate and low TMP filtration, and can effectively promote the homogenization of the feed liquid and weaken the concentration polarization layer, inhibit the rapid growth of the fouling layer on the membrane surface, and achieve efficient filtration. Therefore, the disc-shaped ceramic membrane is an excellent membrane separation material.

[0005] Most of the current molecular sieve membranes are prepared by the secondary growth method. For example, "Preparation and Characterization of NaA Zeolite Membranes Containing Methylcellulose" (DOI: 10.16085 / j.issn.1000-6613.2019-0474) discloses a method for preparing NaA zeolite membranes with different properties by adding methyl cellulose to the synthetic solution, changing the alkalinity, crystallization time, and crystallization temperature of the synthetic solution. "Preparation of Si-rich LTA zeolite membrane using organic template-free solution for methanol dehydration" (https: / / doi.org / 10.1016 / j.seppur.2020.116533) discloses a new type of organic template-free silicon-rich LTA (silicon-aluminum ratio of 1.5) zeolite membrane successfully prepared on a tubular alumina support by the secondary growth method. "Preparation and Permeation Properties of NaA Zeolite Membrane by Vapor Phase Transformation Method" (DOI: 10.4028 / www.scientific.net / AMR.864-867.654) discloses a method for preparing high permeability NaA zeolite membrane by secondary growth method. In these methods, the binding force between the seed and the carrier is poor, which becomes a huge obstacle to the preparation of repeatable and high-quality molecular sieve membranes. Moreover, a large amount of synthesis liquid is required in the synthesis of the secondary growth method, which can easily lead to problems such as waste of synthesis liquid, high production cost, and environmental pollution. Therefore, how to optimize the synthesis effect of molecular sieve membranes and solve problems such as low membrane permeation flux, poor repeatability and high cost has important guiding significance for the industrial application of molecular sieve membranes. Summary of the invention

[0006] Based on the above problems, the present invention provides a disc-shaped molecular sieve membrane with stable high flux and a preparation method thereof. The disc-shaped molecular sieve membrane prepared by the preparation method of the present invention has the advantages of high separation efficiency, good repeatability, low cost, etc.

[0007] In order to achieve the above object, the present invention specifically adopts the following technical solutions: A method for preparing a disc-type molecular sieve membrane with stable high flux comprises the following steps: S1. Pre-treat the disc-shaped ceramic carrier, clean its surface, dry it, calcine it, and cool it for use; mix the molecular sieve seed crystals and water evenly, add an organic modifier to the obtained suspension, mix evenly, and obtain a seed crystal suspension; mix the silicon source, organic structure directing agent, alkali source and deionized water evenly, and age them to obtain a molecular sieve gel synthesis liquid; S2, applying the seed suspension to the pretreated surface of the disc-shaped ceramic carrier and solidifying it; S3, uniformly coating the molecular sieve gel synthesis liquid on the carrier obtained in step S2, and then placing it in a reactor for crystallization; after the crystallization is completed, taking it out, and repeatedly washing it with deionized water until it is neutral, to obtain a molecular sieve membrane; S4, calcining the molecular sieve membrane obtained in step S3 to remove the template agent.

[0008] In a preferred embodiment, the disc-shaped ceramic carrier in step S1 has a round disc-shaped appearance, a spiral permeation channel inside, and an average pore size of 0.5-5 μm.

[0009] In a preferred embodiment, the step of pretreating the disc-shaped ceramic carrier in step S1 includes: ultrasonically cleaning the disc-shaped ceramic carrier with deionized water for 0.5 to 1 hour; drying it naturally after cleaning, calcining it in a muffle furnace at 500 to 600°C for 4 to 8 hours, and cooling it for use.

[0010] In a preferred embodiment, the molecular sieve seed crystal in step S1 is a Silicalite-1 molecular sieve having a particle size of 0.1 to 5 μm.

[0011] In a preferred embodiment, the concentration of the molecular sieve seeds in the seed suspension in step S1 is 0.2 wt % to 5 wt %.

[0012] In a preferred embodiment, the organic modifier in step S1 is prepared into a solution using water and / or ethanol as solvent.

[0013] In a preferred embodiment, the organic modifier in step S1 includes at least one of polyetherimide, polyvinylidene fluoride, polytetrafluoroethylene, and polyethersulfone.

[0014] In a preferred embodiment, the silicon source in step S1 is at least one of silica sol, tetraethyl orthosilicate, silicic acid or sodium silicate.

[0015] In a preferred embodiment, the organic structure directing agent in step S1 is tetrapropylammonium hydroxide and / or tetrapropylammonium bromide.

[0016] In a preferred embodiment, the alkali source in step S1 is sodium hydroxide and / or potassium hydroxide.

[0017] In a preferred embodiment, the concentration of the organic modifier in the seed suspension in step S1 is 0.5 wt % to 10 wt %.

[0018] In a preferred embodiment, the SiO2 in the silicon source, the organic structure directing agent, and the OH in the alkali source in step S1 - The molar ratio of the deionized water is 1:(0.05-0.2):(0.01-0.1):(10-200).

[0019] In a preferred embodiment, the aging conditions in step S1 are: maintaining at 20-50° C. for 6-24 hours.

[0020] In a preferred embodiment, the coating method in step S2 is any one of dipping, hot dipping, vacuum suction, spraying, spin coating or wiping.

[0021] In a preferred embodiment, the coating time in step S2 is 10 to 100 seconds, and the number of coatings is 1 to 3 times.

[0022] In a preferred embodiment, the curing conditions in step S2 are: keeping warm at 170-185° C. for 6-8 hours.

[0023] In a preferred embodiment, the coating method in step S3 is any one of dipping, vacuum suction, wiping, spraying or spin coating.

[0024] In a preferred embodiment, the crystallization conditions in step S3 are: 150-200° C. for 6-12 hours; In a preferred embodiment, the calcination conditions in step S4 are: heating to 500-600° C. at a rate of 0.5-1° C. / min, and maintaining at this temperature for 2-10 hours.

[0025] The present invention also provides a disc-shaped molecular sieve membrane with stable high flux prepared by any of the preparation methods described above. When the disc-shaped molecular sieve membrane is used for dehydration of organic solvents, it exhibits high permeation flux and retention rate, and is suitable for industrial use in dehydration of organic solvents.

[0026] Compared with the prior art, the technical solution of the present invention has the following beneficial effects: (1) The molecular sieve membrane supported by the disc-shaped ceramic support prepared in the present invention overcomes the problem that the traditional tubular support body is prone to membrane contamination, and ensures the permeation flux of the membrane, and can achieve efficient separation of organic solvents and water.

[0027] (2) The method for preparing the butterfly-type molecular sieve membrane provided in the present invention is to coat a seed suspension containing an organic modifier on the surface of a butterfly-type ceramic carrier in a one-step process, thereby strengthening the bonding force between the seed layer and the carrier and improving the coating effect of the molecular sieve seed layer, thereby solving the problems of difficulty in coating a high-quality seed layer on the surface of a tubular ceramic support and the weak contact between the seed layer and the carrier.

[0028] (3) The method for preparing the butterfly-type molecular sieve membrane provided in the present invention can realize the dense and continuous growth of the molecular sieve membrane, solving the problem that it is difficult to synthesize high-quality molecular sieve membranes on macroporous ceramic carriers.

[0029] (4) The method for preparing the butterfly-type molecular sieve membrane provided in the present invention requires less synthetic liquid, which significantly reduces the process cost of the molecular sieve membrane and is easier to industrialize. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 The external shape diagram of the disc-shaped ceramic carrier used in the present invention (Figure (a)) and the structural schematic diagram of the internal spiral permeation channel (Figure (b)); Figure 2 This is a SEM image of the disc-type molecular sieve membrane prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0031] The following content is combined with the embodiments to clearly and completely describe the technical solution of the present application so that those skilled in the art can fully understand the present application. Obviously, the described embodiments are only some preferred embodiments of the present application, rather than all embodiments. Any equivalent transformation or substitution made to the following implementation modes by those of ordinary skill in the art without creative work belongs to the protection scope of the present application.

[0032] The raw materials used in the following examples are all common raw materials on the market and can be directly purchased from the market.

[0033] The specific embodiment of the present application provides a method for preparing a disc-type molecular sieve membrane with a stable high flux, comprising the following steps: S1. Carrier pretreatment, seed suspension preparation and molecular sieve gel synthesis solution preparation The disc-shaped ceramic carrier is placed in an ultrasonic cleaner filled with deionized water and ultrasonically cleaned for 0.5 to 1 hour to remove impurities on its surface and in the channels. After cleaning, the disc-shaped ceramic carrier is naturally dried, and then placed in a muffle furnace at 500 to 600 ° C for calcination for 4 to 8 hours to further remove residual impurities, and then cooled for use. The structure of the disc-shaped ceramic carrier is as follows Figure 1 As shown, its external shape is a disc, with an outer diameter of 0.1m, an inner diameter of 0.02m, and an effective filtration area of ​​0.0625m2 ; Its interior is a spiral permeation channel with an average pore size of 0.5~5μm.

[0034] Mix Silicalite-1 molecular sieve with an average particle size of 0.1~5μm with water, add an organic modifier to the obtained suspension, mix evenly, and obtain a seed suspension. The concentration of Silicalite-1 molecular sieve in the seed suspension is controlled to be 0.2wt%~5wt%, and the concentration of the organic modifier is 0.5wt%~10wt%. Among them, the organic modifier includes at least one of polyetherimide, polyvinylidene fluoride, polytetrafluoroethylene, and polyether sulfone. The organic modifier can be directly added to the mixture of Silicalite-1 molecular sieve and water, or it can be added to the mixture of Silicalite-1 molecular sieve and water after being prepared into a solution with water or / and ethanol.

[0035] The silicon source, organic structure directing agent (OSDA), alkali source and deionized water are mixed evenly, and then kept at 20-50°C for 6-24 hours for aging to obtain a molecular sieve gel synthesis solution. The silicon source is at least one of silica sol, tetraethyl orthosilicate, silicic acid or sodium silicate. The organic structure directing agent is tetrapropylammonium hydroxide or / and tetrapropylammonium bromide. The alkali source is sodium hydroxide or / and potassium hydroxide. SiO2 in the silicon source, the organic structure directing agent, and OH in the alkali source are mixed evenly, and then kept at 20-50°C for 6-24 hours for aging to obtain a molecular sieve gel synthesis solution. The silicon source is at least one of silica sol, tetraethyl orthosilicate, silicic acid or sodium silicate. The organic structure directing agent is tetrapropylammonium hydroxide or / and tetrapropylammonium bromide. The alkali source is sodium hydroxide or / and potassium hydroxide. - , the molar ratio of deionized water is 1:(0.05~0.2):(0.01~0.1):(10~200).

[0036] S2. Applying seed crystals: Apply the seed crystal suspension to the surface of the pretreated disc-shaped ceramic carrier 1 to 3 times in 10 to 100 seconds, and then keep it at 170 to 185°C for 6 to 8 hours for curing. The seed crystal suspension coating method is any one of the following: dipping method, hot dipping method, vacuum suction method, spraying method, spin coating method or rubbing method.

[0037] S3, preparing a molecular sieve membrane: the molecular sieve gel synthesis liquid is evenly coated on the carrier obtained in step S2, and then placed in a reactor and maintained at 150-200°C for 6-12 hours for crystallization. After the crystallization is completed, it is taken out and repeatedly rinsed with deionized water until neutral to obtain a molecular sieve membrane. The method for coating the molecular sieve gel synthesis liquid is any one of an immersion method, a vacuum suction method, a wiping method, a spraying method or a spin coating method.

[0038] S4, removing the template agent: calcining the molecular sieve membrane obtained in step S3 at 500-600° C. for 2-10 hours to remove the template agent. The heating rate is controlled at 0.5-1° C. / min.

[0039] As an example, the average pore size of the disc-shaped ceramic carrier is 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1 μm, 1.2 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm or 5 μm.

[0040] As an example, the average particle size of the Silicalite-1 molecular sieve is 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, ... 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm or 5 μm.

[0041] As an example, the concentration of Silicalite-1 molecular sieve in the seed suspension is 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt% ... 2 wt%, 2.1 wt%, 2.2 wt%, 2.5 wt% ... 4.8 wt% or 5 wt%.

[0042] As an example, the concentration of the organic modifier in the seed suspension is 0.5wt%, 0.6wt%, 0.7wt%, 0.8wt%, 1wt%, 1.5wt%, 2wt%, 2.5wt%, 3wt%, 3.5wt%, 4wt%, 4.5wt%, 5wt%, 5.5wt%, 6wt%...10wt%.

[0043] As an example, SiO2 in the silicon source, organic structure directing agent, OH in the alkali source - , the molar ratio of deionized water is 1:0.05:0.01:10, 1:0.05:0.01:80, 1:0.05:0.01:100, 1:0.06:0.03:50, 1:0.08:0.05:80, 1:0.1:0.08:150, 1:0.1:0.1:150 or 1:0.1:0.1:200.

[0044] Example 1 A method for preparing a disc-type molecular sieve membrane with stable high flux comprises the following steps: S1. Carrier pretreatment, seed suspension preparation and molecular sieve gel synthesis solution preparation The disc-shaped ceramic carrier with an average pore size of 2μm was ultrasonically cleaned for 0.5h, dried naturally, calcined at 500℃ for 6h, and cooled for use. Silicalite-1 molecular sieve seeds with an average particle size of 2μm and deionized water were mixed evenly, and polyetherimide (PEI) was added to the obtained suspension and mixed evenly to obtain a seed suspension. The concentration of Silicalite-1 molecular sieve seeds in the seed suspension was 0.5wt%, and the concentration of PEI was 2wt%. Silica sol, tetrapropylammonium hydroxide, sodium hydroxide and deionized water were mixed according to SiO2:tetrapropylammonium hydroxide:OH - :H2O=1:0.05:0.01:100, stirred and aged at 20°C for 24h to obtain a molecular sieve gel synthesis liquid.

[0045] S2. Applying seed crystals: Apply the seed crystal suspension to the pretreated carrier surface within 80 seconds by spraying, spray once, and then place the carrier at 170° C. for 8 hours for curing.

[0046] S3, preparing molecular sieve membrane: the molecular sieve gel synthesis liquid is evenly coated on the carrier obtained in step S2 by dipping method, and then placed in a reactor for crystallization at 170° C. for 10 hours. After crystallization, it is taken out and repeatedly rinsed with deionized water until neutral to obtain a molecular sieve membrane.

[0047] S4, removing the template agent: calcining the molecular sieve membrane obtained in step S3 at 600° C. for 3 h to remove the template agent. The heating rate is controlled to be 0.5° C. / min.

[0048] Figure 2 The SEM image of the disc-shaped molecular sieve membrane prepared in this embodiment shows that the molecular sieve membrane prepared by the method of this embodiment has uniform grain size and regular arrangement, and the membrane layer has excellent uniformity and density.

[0049] Example 2 A method for preparing a disc-type molecular sieve membrane with stable high flux comprises the following steps: S1. Carrier pretreatment, seed suspension preparation and molecular sieve gel synthesis solution preparation The disc-shaped ceramic carrier with an average pore size of 0.5 μm was ultrasonically cleaned for 1 hour, dried naturally, calcined at 600 ° C for 4 hours, and cooled for use. Silicalite-1 molecular sieve seeds with an average particle size of 0.5 μm and deionized water were mixed evenly, and an ethanol solution of polytetrafluoroethylene (PTFE) was added to the obtained suspension and mixed evenly to obtain a seed suspension. The concentration of Silicalite-1 molecular sieve seeds in the seed suspension is 2wt%, and the concentration of PTFE is 5wt%. Silicic acid, tetrapropylammonium bromide, sodium hydroxide and deionized water are mixed according to SiO2:tetrapropylammonium bromide:OH- :H2O=1:0.1:0.1:200 in a molar ratio, stirred and aged at 50°C for 6h to obtain a molecular sieve gel synthesis liquid.

[0050] S2. Coating seed crystals: The seed crystal suspension is coated on the pretreated carrier surface within 10 seconds by dipping method, and the coating is repeated 3 times. Then the carrier is placed at 185° C. for 6 hours for curing.

[0051] S3, preparing molecular sieve membrane: the molecular sieve gel synthesis liquid is evenly coated on the carrier obtained in step S2 by dipping method, and then the carrier is taken out and placed in a reactor for crystallization at 150° C. for 12 hours. After the crystallization is completed, it is taken out and repeatedly rinsed with deionized water until it is neutral to obtain a molecular sieve membrane.

[0052] S4, removing the template agent: calcining the molecular sieve membrane obtained in step S3 at 500° C. for 10 hours to remove the template agent. The heating rate is controlled to be 1° C. / min.

[0053] Example 3 A method for preparing a disc-type molecular sieve membrane with stable high flux comprises the following steps: S1. Carrier pretreatment, seed suspension preparation and molecular sieve gel synthesis solution preparation The disc-shaped ceramic carrier with an average pore size of 3μm was ultrasonically cleaned for 0.8h, naturally dried, calcined at 550℃ for 8h, and cooled for use. Silicalite-1 molecular sieve seeds with an average particle size of 5μm and deionized water were mixed evenly, polyethersulfone (PES) was added to the obtained suspension, and mixed evenly to obtain a seed suspension. The concentration of Silicalite-1 molecular sieve seeds in the seed suspension is 5wt%, and the concentration of PES is 10wt%. Ethyl orthosilicate, tetrapropylammonium hydroxide, potassium hydroxide and deionized water are mixed according to SiO2:tetrapropylammonium hydroxide:OH - :H2O= 1:0.1:0.08:150 in a molar ratio, stirred and aged at 35°C for 12h to obtain a molecular sieve gel synthesis solution.

[0054] S2. Coating seed crystals: Spin-coat the seed crystal suspension onto the pretreated carrier surface within 100 seconds, repeat coating twice, and then place the carrier at 170° C. for 8 hours for curing.

[0055] S3, preparing molecular sieve membrane: the molecular sieve gel synthesis liquid is uniformly coated on the carrier obtained in step S2 by spraying, and then placed in a reactor for crystallization at 200° C. for 6 hours. After the crystallization is completed, it is taken out and repeatedly rinsed with deionized water until it is neutral to obtain a molecular sieve membrane.

[0056] S4, removing the template agent: calcining the molecular sieve membrane obtained in step S3 at 550° C. for 7 h to remove the template agent. The heating rate is controlled to be 0.8° C. / min.

[0057] Comparative Example 1 This comparative example provides a method for preparing a disc-type molecular sieve membrane with a stable high flux, and the steps are basically the same as those in Example 1, except that: in step S1, Silicalite-1 molecular sieve seeds with an average particle size of 2 μm and deionized water are uniformly mixed, and the obtained suspension is used as a seed suspension. That is, compared with Example 1, the difference between this comparative example and Example 1 is that no organic modifier is added to the seed suspension.

[0058] Comparative Example 2 This comparative example provides a method for preparing a disc-type molecular sieve membrane with a stable high flux, and the steps are basically the same as those in Example 1, except that: In step S1, Silicalite-1 molecular sieve seed crystals with an average particle size of 2 μm and deionized water are uniformly mixed to obtain a suspension as a seed crystal suspension.

[0059] In step S2, the seed suspension in step S1 is first applied to the pretreated carrier surface by spraying within 40 seconds, and the spraying is performed once; then a 2wt% polyetherimide aqueous solution is applied to the carrier surface coated with the seed suspension by spraying within 40 seconds, and the spraying is performed once, and then the carrier is placed at 170° C. for 8 hours for curing.

[0060] Comparative Example 3 This comparative example provides a method for preparing a disc-type molecular sieve membrane with stable high flux, and the steps are basically the same as those in Example 2, except that: in step S3, the carrier obtained in step S2 is immersed in a molecular sieve gel synthesis liquid, and the carrier immersed in the molecular sieve gel synthesis liquid (that is, the carrier and the molecular sieve gel synthesis liquid together) is placed in a reactor for crystallization at 150° C. for 12 hours. After the crystallization is completed, it is taken out and repeatedly rinsed with deionized water until neutral to obtain a molecular sieve membrane.

[0061] Disc type molecular sieve membrane performance test In order to understand the separation effect of the disc-type molecular sieve membranes prepared in Examples 1 to 3 and Comparative Examples 1 to 3, flux and rejection rate tests were conducted. The specific test methods are as follows: The disc-type molecular sieve membranes prepared in different embodiments and comparative examples were used to separate a mixture of 90 wt% ethanol and water at 75°C. The permeation flux of the disc-type molecular sieve membrane was calculated by measuring the mass of the permeate per unit time. The permeation flux after continuous operation for 100 hours was measured, and the stability of the disc-type molecular sieve membrane was characterized according to the degree of permeation flux decrease. The permeation flux and retention rate in the process of material-liquid separation were calculated according to formulas (1) and (2), respectively. The results are shown in Table 1.

[0062] Formula (1): J0=V1 / A·t·TMP; Formula (2): R = ( C in - C out ) / C in ×100%.

[0063] Where J0 is the permeate flux of feed-liquid separation L / (m 2 ·h·bar); V1 is the permeation volume L for feed-liquid separation; A is the effective membrane area m 2 ; t is the permeation time h; TMP is the transmembrane pressure difference bar. R is the retention rate of the feed liquid;% C in is the mass concentration of water in the raw material solution in mg / L; C out It is the concentration of water in the filtrate after filtration in mg / L.

[0064] Table 1 Separation effects of various disc-type molecular membranes

[0065] As can be seen from Table 1, compared with the preparation method in the comparative example, the disc-type molecular sieve membrane prepared by the method in this application has a higher permeation flux and retention rate; after continuous operation for 100 hours, the permeation flux of Example 3 (decreased by 12.5%) with the largest decrease in the embodiment is lower than that of Example 3 (decreased by 16.7%) with the smallest decrease in the comparative example, which indicates that the butterfly-type molecular sieve membrane prepared in this application has excellent stability. Therefore, the butterfly-type molecular sieve membrane prepared by the method in this application is suitable for use in the field of organic solvent dehydration.

[0066] The above-described embodiments are only preferred embodiments of the present application and are not intended to limit the scope of protection of the present application. For any person skilled in the art, the present application may have various changes and modifications. Any simple equivalent changes and modifications made based on the scope of protection of the present application and the contents of the specification should be included in the scope of protection of the present application.

Claims

1. A method for preparing a disc-type molecular sieve membrane with stable high flux, characterized in that: The following steps are involved: S1. Pre-treat the disc-shaped ceramic carrier, clean its surface, dry it, calcine it, and cool it for use; mix the molecular sieve seed crystals and water evenly, add an organic modifier to the obtained suspension, mix evenly, and obtain a seed crystal suspension; mix the silicon source, organic structure directing agent, alkali source and deionized water evenly, and age them to obtain a molecular sieve gel synthesis liquid; S2, applying the seed suspension to the pretreated surface of the disc-shaped ceramic carrier and solidifying it; S3, uniformly coating the molecular sieve gel synthesis liquid on the carrier obtained in step S2, and then placing it in a reactor for crystallization; after the crystallization is completed, taking it out, and repeatedly washing it with deionized water until it is neutral, to obtain a molecular sieve membrane; S4, calcining the molecular sieve membrane obtained in step S3 to remove the template agent.

2. The preparation method according to claim 1, characterized in that: The disc-shaped ceramic carrier in step S1 has a round disc-shaped appearance, a spiral permeation channel inside, and an average pore size of 0.5-5 μm; Or / and, the coating method in step S2 is any one of dipping, hot dipping, vacuum suction, spraying, spin coating or wiping; Or / and, the coating method in step S3 is any one of dipping, vacuum suction, wiping, spraying or spin coating.

3. The preparation method according to claim 1, characterized in that: The step of pre-treating the disc-shaped ceramic carrier in step S1 includes: ultrasonically cleaning the disc-shaped ceramic carrier with deionized water for 0.5 to 1 hour; naturally drying after cleaning, calcining in a muffle furnace at 500 to 600° C. for 4 to 8 hours, and cooling for standby use; Or / and, in step S2, the coating time is 10 to 100 seconds, and the number of coatings is 1 to 3 times; Or / and, the curing condition in step S2 is: keeping warm at 170-185° C. for 6-8 hours.

4. The preparation method according to claim 1, characterized in that: The molecular sieve seed crystals in step S1 are Silicalite-1 molecular sieves with a particle size of 0.1 to 5 μm; or / and, the concentration of the molecular sieve seed crystals in the seed crystal suspension is 0.2 wt% to 5 wt%.

5. The preparation method according to claim 1, characterized in that: The organic modifier is prepared into a solution using water and / or ethanol as solvent; Or / and, the organic modifier includes at least one of polyetherimide, polyvinylidene fluoride, polytetrafluoroethylene, and polyethersulfone; Or / and, the organic structure directing agent is tetrapropylammonium hydroxide or / and tetrapropylammonium bromide.

6. The preparation method according to claim 1, characterized in that: The silicon source is at least one of silica sol, tetraethyl orthosilicate, silicic acid or sodium silicate; or / and, the alkali source is sodium hydroxide or / and potassium hydroxide.

7. The preparation method according to claim 1, characterized in that: The concentration of the organic modifier in the seed suspension is 0.5wt% to 10wt%; or / and, SiO2 in the silicon source, the organic structure directing agent, OH in the alkali source - The molar ratio of the deionized water is 1:(0.05-0.2):(0.01-0.1):(10-200).

8. The preparation method according to claim 1, characterized in that: The aging conditions in step S1 are: maintaining at 20-50° C. for 6-24 hours; Or / and, the crystallization conditions in step S3 are: 150-200° C. for 6-12 hours; Or / and, the calcination conditions in step S4 are: heating to 500-600° C. at a rate of 0.5-1° C. / min, and then maintaining for 2-10 hours.

9. A disc-shaped molecular sieve membrane with stable high flux prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the disc-shaped molecular sieve membrane with stable high flux prepared by the preparation method according to any one of claims 1 to 8 in dehydration of organic solvents.

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