CN111389236A - Efficient separation ultrathin defect-free molecular sieve membrane and preparation method thereof - Google Patents
Efficient separation ultrathin defect-free molecular sieve membrane and preparation method thereof Download PDFInfo
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Abstract
Compared with the prior art, the invention utilizes the advantage that the layered molecular sieve is easy to form a film, preferentially assembles a layered molecular sieve layer on the surface of a carrier, then dissolves the layered molecular sieve layer under the acid or alkali condition to generate a structural infinitesimal layer, and utilizes the characteristic that the structural infinitesimal promotes the molecular sieve with the same or similar structural infinitesimal to grow along the surface of the molecular sieve, so that the structural infinitesimal layer grows in a target molecular sieve film synthetic liquid and gradually forms twin crystals, and finally forms the target molecular sieve film. The method combines the advantages of two-dimensional material film forming and three-dimensional material film forming, overcomes the problems of thick film layer and defect after the three-dimensional material film forming, and prepares the molecular sieve film which is high-efficiency separated, ultrathin and has no defect. The preparation method has the advantages of simple preparation process, easy control, high crystallinity, thin molecular sieve membrane layer, high quality, excellent separation performance and better technical effect.
Description
Technical Field
The invention belongs to the field of membrane separation, and particularly relates to an efficient separation ultrathin defect-free molecular sieve membrane and a preparation method thereof.
Background
The molecular sieve membrane shows great potential in the separation field due to the adjustable and uniform pore diameter, the pore size close to the molecular size, and high chemical stability, thermal stability and mechanical strength. However, the application of the molecular sieve membrane is severely restricted by the thick and defective membrane layer. Due to the existence of defects, the separation mixture diffuses to the permeation side of the membrane through defect short circuit, so that the molecular sieving effect is weakened or even completely eliminated, the separation performance of the molecular sieving membrane is greatly reduced, and even the separation effect is lost. Although various molecular sieve membrane preparation methods, post-treatment methods and repair methods are continuously used to avoid or eliminate defects in the molecular sieve membranes and to some extent, higher quality molecular sieve membranes can be prepared, the defects in the molecular sieve membranes still cannot be completely eliminated.
It is worth pointing out that the thickness of the membrane layer gradually increases with the increase of the synthesis or treatment times, which greatly increases the resistance of the substance passing through the membrane layer and reduces the permeability of the molecular sieve membrane. The research shows that if the thickness of the molecular sieve membrane layer is controlled at a nanometer level, the permeation flux of the molecular sieve membrane can be improved by several times or even several orders of magnitude. Considering that the thickness of the molecular sieve membrane is generally in micron level and the permselectivity is poor at present, the task of reducing the thickness of the membrane layer is heavy and far. Therefore, how to effectively improve the quality of the membrane layer and reduce the thickness of the membrane layer becomes an important scientific problem to be solved urgently in the preparation process of the molecular sieve membrane with high permeation flux and high selectivity.
Disclosure of Invention
The invention aims to provide a preparation method for efficiently separating an ultrathin defect-free molecular sieve membrane. Firstly, assembling a layered molecular sieve layer on a rough carrier, then carrying out secondary treatment on the layered molecular sieve layer to prepare a structural infinitesimal layer, and finally constructing a target molecular sieve membrane by using the structural infinitesimal layer. The method combines the advantages of two-dimensional material film forming and three-dimensional material film forming, overcomes the problems of thick film layer and defect, and prepares the molecular sieve film with high efficiency separation, ultra-thin and no defect.
The invention also aims to provide the ultrathin defect-free molecular sieve membrane for efficient separation, which has the advantages of thin and uniform membrane layer, good compactness, good stability, high repeatability and excellent performance.
The specific technical scheme of the invention is as follows:
a preparation method for efficiently separating an ultrathin defect-free molecular sieve membrane comprises the following steps:
1) assembling a layered molecular sieve on the surface of a porous carrier;
2) treating the porous carrier treated in the step 1) in an acidic or alkaline solution to dissolve the layered molecular sieve to generate a structural infinitesimal layer;
3) and 2) crystallizing and synthesizing the porous carrier treated in the step 2) and the target molecular sieve membrane synthetic liquid to obtain the high-efficiency separation ultrathin defect-free molecular sieve membrane.
In the step 1), the porous carrier is a sheet or tubular hollow structure, and is preferably porous ceramic or porous metal.
The layered molecular sieve described in step 1) includes, but is not limited to, the following structure types of molecular sieves: CDO, MWW, FER, layered MFI, layered AFO or layered MOF molecular sieves.
The diameter-thickness ratio of the layered molecular sieve in the step 1) is more than 20, and the thickness is less than 500 nm.
The layered molecular sieve in the step 1) and the molecular sieve in the target molecular sieve membrane in the step 3) have the same or similar structural microelements, such as secondary structural units, layered fragments and the like which are all the same. For example, both MWW and CHA molecular sieves contain double six-membered ring secondary building blocks, both CDO and MFI molecular sieves contain mor secondary building blocks, and MWW and SOD molecular sieves contain similar lamellar fragments.
The step 1) of assembling the layered molecular sieve refers to: the layered molecular sieve is spread on the surface of the porous carrier in a single-layer or multi-layer mode by using the methods of layer-by-layer dip coating, wiping coating, spray coating, spin coating, self-assembly or vacuum filtration and the combination of the methods.
The step 2) is specifically as follows: soaking the porous carrier treated in the step 1) in an acidic or alkaline solution for 0.5 to 12 hours, preferably, the soaking temperature is 20 to 100 ℃;
the acidic or alkaline solution in the step 2) refers to: an acidic or alkaline target molecular sieve membrane synthetic solution, or an alkali solution with the mass concentration of 0.5-30% or an acid solution with the mass concentration of 0.5-30%.
If the acidic or alkaline solution is an alkali solution with the mass concentration of 0.5-30% or an acid solution with the mass concentration of 0.5-30%, the carrier needs to be slowly taken out of the solution after treatment and transferred to the target molecular sieve membrane synthetic solution for crystallization synthesis.
The specific preparation method of the target molecular sieve membrane synthetic fluid in the step 3) comprises the following steps: dissolving or dispersing any one or more of an aluminum source, a silicon source, a phosphorus source, an alkali source or a template agent required by synthesizing the target molecular sieve membrane in a solvent, mixing the solution under high-speed stirring, and stirring the solution at room temperature for 1 to 48 hours to obtain the target molecular sieve membrane synthetic solution.
Preferably, the preparation method of the SOD molecular sieve membrane synthetic fluid comprises the following steps: dissolving an aluminum source and an alkali source in deionized water, continuously stirring for 2h to completely dissolve the aluminum source and the alkali source, cooling to room temperature, slowly adding the silicon source into the mixture, and stirring at room temperature for 1h-24h to obtain the target molecular sieve membrane synthetic solution.
In the step 3), the crystallization synthesis specifically comprises the following steps: reacting for 0.5-96h at 60-200 ℃.
The target molecular sieve membrane in the step 3) is a molecular sieve membrane including but not limited to L TA, MFI, SOD, FAU, ZIF, CHA or MOF and the like.
The target molecular sieve membrane in the step 3) is different from the layered molecular sieve in the step 1) in structure type.
Further, after the crystallization synthesis reaction in the step 3) is finished, cooling the temperature of the synthesis solution to room temperature, washing the porous carrier with deionized water, and drying to obtain the dense defect-free target molecular sieve membrane grown on the surface of the porous carrier. The washing refers to repeatedly washing for several times by using deionized water until the pH value of a washing solution is 7; the drying refers to drying for 24 hours at 100 ℃.
Further, in the step 3), when the target molecular sieve membrane synthetic solution contains a template which cannot be removed by drying, the template is removed by baking after drying.
The invention provides a high-efficiency separation ultrathin defect-free molecular sieve membrane which is prepared by adopting the method. The thickness of the film layer is less than 1 micron, the film layer is uniform and has no obvious defects on the surface, the alcohol-water separation efficiency is higher than 10000, and the permeation flux of water is higher than 4 kg.m-2·h-1。
The TO4(T represents a framework element) primary structural unit in the molecular sieve forms secondary structural units (SBUs) such as a four-membered ring, a six-membered ring and an eight-membered ring through sharing oxygen atoms, cages or crystal holes are formed among the secondary structural units through sharing oxygen atoms, and the cages share a ring TO form molecular sieve pore passages. The structural microelements are nano-scale particles formed by single secondary structural units or a plurality of secondary structural units, or are layered fragments formed by primary structural units, and the like.
Compared with the prior art, the invention utilizes the advantage that the layered molecular sieve is easy to form a film, preferentially assembles the layered molecular sieve layer on the surface of the carrier, then dissolves the layered molecular sieve layer under the acid or alkali condition to generate the structural infinitesimal layer, and utilizes the characteristic that the structural infinitesimal layer promotes the molecular sieve with the same or similar structural infinitesimal to grow along the surface of the molecular sieve layer to ensure that the structural infinitesimal layer grows in the target molecular sieve film synthetic fluid and gradually forms twin crystals, thereby finally forming the target molecular sieve film. The method combines the advantages of two-dimensional material film forming and three-dimensional material film forming, overcomes the problems of thick film layer and defect after the three-dimensional material film forming, and prepares the molecular sieve film which is high-efficiency separated, ultrathin and has no defect. The preparation method has the advantages of simple preparation process, easy control, high crystallinity, high molecular sieve membrane quality, excellent separation performance and better technical effect.
Drawings
FIG. 1 is an XRD pattern of the SOD molecular sieve membrane obtained in example 1;
FIG. 2 is an SEM photograph of the SOD molecular sieve membrane obtained in example 1;
FIG. 3 is an SEM image of the NaA molecular sieve membrane obtained in example 2;
FIG. 4 is an SEM picture of a ZSM-5 molecular sieve membrane obtained in example 3;
FIG. 5 is an SEM photograph of the SOD zeolite membrane obtained in comparative example 1;
FIG. 6 is a schematic view of the preparation method of the present invention.
Detailed Description
The invention is further illustrated by the following examples.
Example 1
A preparation method for efficiently separating an ultrathin defect-free molecular sieve membrane comprises the following steps:
1) uniformly dispersing a layered MCM-22 molecular sieve (one MWW molecular sieve) into an ethanol solution, and performing ultrasonic dispersion for 1h to prepare an MCM-22 molecular sieve ethanol suspension with the concentration of 1 g/L.
2) Vertically immersing the sheet ceramic carrier in the MCM-22 molecular sieve ethanol suspension in the step 1) for 1min to enable the MCM-22 molecular sieve to be adsorbed on the surface of the sheet ceramic carrier. The carrier was taken out and dried at 110 ℃ for 6 h. In order to obtain a uniformly dispersed MCM-22 molecular sieve layer, the above dipping and drying process was repeated 3 times. The vertical placement is to avoid the molecular sieve nucleated and grown in the solution from depositing on the surface of the carrier to influence the growth of a molecular sieve film;
3) 0.82g of sodium aluminate is dissolved in 52.45g of deionized water, 19.6g of sodium hydroxide are added with stirring, stirring is continued for 2h to dissolve completely and cooling is carried out to room temperature. Slowly dripping the SOD into 45g of silica sol containing 1.5 of silicon dioxide under high-speed stirring, stirring at room temperature for 24h to obtain a synthetic solution for synthesizing the SOD molecular sieve membrane, placing the carrier treated in the step 2) into the synthetic solution for synthesizing the SOD molecular sieve membrane, and standing at 30 ℃ for 30 min. The synthetic solution for synthesizing the SOD molecular sieve membrane is alkaline solution, and the carrier treated in the step 2) is placed in the synthetic solution and stands for 30min at 30 ℃ to dissolve the layered molecular sieve layer to generate a structural infinitesimal layer.
4) Transferring the synthetic liquid of the SOD molecular sieve membrane containing the porous carrier treated in the step 3) to a crystallization kettle together for sealing, heating the crystallization kettle to 140 ℃, and carrying out heat preservation and crystallization reaction for 4 hours. And after crystallization, taking out the carrier, repeatedly washing the carrier for several times by using deionized water until the pH value of a washing liquid is 7, and drying the washed carrier for 24 hours at 100 ℃ to obtain the high-efficiency separation ultrathin defect-free SOD molecular sieve membrane.
5) Performing pervaporation test on the SOD molecular sieve membrane prepared in the step 4), wherein the permeation flux of the SOD molecular sieve membrane is 8.3 kg.m-2·h-1And the alcohol-water permselectivity is more than 10000.
FIG. 1 is an XRD pattern of the SOD molecular sieve membrane obtained in example 1, ■ represents the diffraction peak of alumina, JCPD #41-0009 is the standard diffraction peak of SOD molecular sieve, XRD pattern shows that the surface of the carrier is precoated with MCM-22 molecular sieve layer, and the SOD molecular sieve membrane can be generated on the surface of the ceramic carrier by crystallizing at 140 ℃ for 4h, meanwhile, the diffraction peak of MCM-22 molecular sieve is not appeared on the surface of the carrier.
FIG. 2 is a SEM image of the SOD molecular sieve membrane obtained in the present example: (a) is a plan view, and (b) is an interface view. SEM picture shows that MCM-22 molecular sieve layer is pre-coated on the surface of the carrier, and a dense, flat and defect-free SOD molecular sieve membrane can be generated on the surface of the ceramic carrier by crystallizing for 4h at 140 ℃, and the thickness of the membrane layer is only 700 nm.
Example 2
A preparation method for efficiently separating an ultrathin defect-free molecular sieve membrane comprises the following steps:
1) and rubbing the surface of the tubular ceramic carrier with an AMH-3 molecular sieve layer by using a rubbing method.
2) 4.1g of sodium aluminate are dissolved in 83g of deionized water, 4g of sodium hydroxide are added with stirring, stirring is continued for 2h to dissolve it completely and cooling is carried out to room temperature. Then slowly dropwise adding the NaA molecular sieve membrane into 10g of silica sol containing 30% of silicon dioxide under high-speed stirring, and stirring for 24 hours at room temperature to obtain a NaA molecular sieve membrane synthetic solution. Placing the carrier treated in the step 1) in a NaA molecular sieve membrane synthetic solution, and standing for 2 hours at 50 ℃. The NaA molecular sieve membrane synthetic solution is an alkaline solution, and the carrier treated in the step 1) is placed in the synthetic solution and stands for 2 hours at 50 ℃ to dissolve the AMH-3 molecular sieve layer to generate a structure infinitesimal layer;
3) transferring the NaA molecular sieve membrane (one of L TA type molecular sieves) synthetic solution containing the porous carrier treated in the step 2) into a crystallization kettle for sealing, heating the crystallization kettle to 90 ℃, carrying out heat preservation and crystallization reaction for 24h, taking out the carrier after crystallization is finished, repeatedly washing the carrier for several times by using deionized water until the pH value of a washing solution is 7, and drying the carrier for 24h at 100 ℃ to obtain the NaA molecular sieve membrane.
4) Carrying out pervaporation test on the NaA molecular sieve membrane prepared in the step 3), wherein the permeation flux of the NaA molecular sieve membrane is 6.1 kg.m-2·h-1And the alcohol-water permselectivity is more than 10000.
FIG. 3 is an SEM image of the NaA molecular sieve membrane obtained in example 2;
example 3
A preparation method for efficiently separating an ultrathin defect-free molecular sieve membrane comprises the following steps:
1) uniformly dispersing the layered UZM-25 molecular sieve (one of CDO molecular sieves) into a methanol solution, and performing ultrasonic dispersion for 1h to prepare a methanol suspension of the UZM-25 molecular sieve with the concentration of 5 g/L.
2) And spin-coating a UZM-25 molecular sieve layer on the surface of the flaky ceramic carrier by using a spin-coating method.
3) 0.0078g of sodium aluminate and 1.43g of sodium hydroxide are dissolved in 83.68g of deionized water, 7.94g of ammonium tetrapropylhydroxide as a template are added while stirring, and stirring is continued for 0.5h to completely dissolve the sodium aluminate and cool to room temperature. Then 9.92g of tetraethoxysilane-containing solution is slowly dripped into the solution and stirred for 12 hours at room temperature to obtain the ZSM-5 molecular sieve (one of MFI molecular sieves) membrane synthetic solution.
4) Vertically placing the flaky ceramic carrier treated in the step 2) in a 1% nitric acid solution, and standing for 6 hours at 90 ℃ to dissolve the layered molecular sieve layer to generate a structural infinitesimal layer.
5) Vertically and slowly pulling out the porous carrier treated in the step 4), transferring the porous carrier into a crystallization kettle containing the ZSM-5 molecular sieve membrane synthetic liquid prepared in the step 3), sealing the crystallization kettle, and heating the crystallization kettle to 180 ℃ for heat preservation and crystallization reaction for 72 hours. And after crystallization, taking out the carrier, repeatedly washing the carrier for several times by using deionized water until the pH value of a washing solution is 7, drying the carrier for 24 hours at the temperature of 100 ℃, finally heating the carrier to 550 ℃ at the temperature rise rate of 5 ℃/min, and keeping the temperature for 6 hours to bake out the template agent to obtain the ZSM-5 molecular sieve membrane.
6) Carrying out pervaporation test on the ZSM-5 molecular sieve membrane prepared in the step 5), wherein the permeation flux of the ZSM-5 molecular sieve membrane is 4.1 kg.m-2·h-1Alcohol water osmotic selectionThe sex is more than 10000.
FIG. 4 is an SEM picture of a ZSM-5 molecular sieve membrane obtained in example 3;
example 4
A preparation method for efficiently separating an ultrathin defect-free molecular sieve membrane comprises the following steps:
1) uniformly dispersing a layered ITQ-1 molecular sieve (one MWW molecular sieve) into an ethanol solution, and performing ultrasonic dispersion for 2 hours to prepare an ITQ-1 molecular sieve ethanol suspension with the concentration of 0.5 g/L.
2) And a layer of ITQ-1 molecular sieve layer is subjected to suction filtration on the inner surface of the tubular ceramic carrier by using a vacuum filtration method.
3) 8.16g of aluminum isopropoxide and 3.92g of phosphoric acid were dissolved in 54g of deionized water, and 1.2g of 30% silica sol was added with stirring, and stirring was continued for 2 hours. Then 2.94g of tetraethylammonium hydroxide and 5.4g of diphenylamine are slowly added dropwise into the mixture, and the mixture is stirred at room temperature for 48 hours to obtain SAPO-34 molecular sieve (one of CHA molecular sieves) membrane synthesis solution.
4) The carrier containing the ITQ-1 molecular sieve layer is vertically placed in 10 percent sodium hydroxide solution and stands for 1h at the temperature of 50 ℃ to obtain the structural microelements.
5) Vertically and slowly pulling out the porous carrier treated in the step 4), transferring the porous carrier into a crystallization kettle containing the SAPO-34 molecular sieve membrane synthetic liquid prepared in the step 3), sealing the crystallization kettle, and heating the crystallization kettle to 200 ℃ for heat preservation and crystallization reaction for 24 hours. And after crystallization, taking out the carrier, repeatedly washing the carrier for several times by using deionized water until the pH value of the washing liquid is 7, drying the carrier for 24 hours at the temperature of 100 ℃, raising the temperature to 400 ℃ at the heating rate of 1 ℃/min, and keeping the temperature for 10 hours to roast the carrier to remove the template agent, thereby obtaining the SAPO-34 molecular sieve membrane.
6) Carrying out pervaporation test on the ZSM-5 molecular sieve membrane prepared in the step 5), wherein the permeation flux of the ZSM-5 molecular sieve membrane is 5.1 kg.m-2·h-1And the alcohol-water permselectivity is more than 10000.
Comparative example 1
A preparation method of a molecular sieve membrane comprises the following steps:
1) 0.82g of sodium aluminate is dissolved in 52.45g of deionized water, 19.6g of sodium hydroxide are added with stirring, stirring is continued for 2h to dissolve completely and cooling is carried out to room temperature. Then slowly dropwise adding the SOD into 45g of silica sol containing 1.5g of silicon dioxide under high-speed stirring, and stirring for 24 hours at room temperature to obtain the SOD molecular sieve membrane synthetic solution. Placing the sheet ceramic carrier in the synthetic solution, and standing at 30 deg.C for 30 min.
2) Transferring the synthetic liquid containing the porous carrier treated in the step 1) to a crystallization kettle for sealing, and heating the crystallization kettle to 140 ℃ for heat preservation and crystallization reaction for 4 hours. And after crystallization, taking out the carrier, repeatedly washing the carrier for several times by using deionized water until the pH value of the washing liquid is 7, and drying to obtain the SOD molecular sieve membrane.
3) Performing pervaporation test on the SOD molecular sieve membrane prepared in the step 3), although the permeation flux of the SOD molecular sieve membrane is up to 20.7 kg.m-2·h-1But almost not selective for aqueous ethanol mixtures.
FIG. 5 is an SEM image of the SOD molecular sieve membrane obtained in this example: (a) is a plan view, and (b) is an interface view. SEM shows that SOD molecular sieve membrane can be formed on the inner wall of ceramic carrier when molecular sieve membrane is prepared by original growth method. However, the membrane layer contains a large number of defects, the molecular sieve membrane is discontinuous, and the existence of the defects seriously influences the performance of the molecular sieve membrane.
Comparative example 2
A preparation method of a molecular sieve membrane comprises the following steps:
1) uniformly dispersing the layered UZM-25 molecular sieve (one of CDO molecular sieves) into a methanol solution, and performing ultrasonic dispersion for 1h to prepare a methanol suspension of the UZM-25 molecular sieve with the concentration of 5 g/L.
2) And spin-coating a UZM-25 molecular sieve layer on the surface of the flaky ceramic carrier by using a spin-coating method.
3) 0.0078g of sodium aluminate and 1.43g of sodium hydroxide were dissolved in 83.68g of deionized water, and 7.94g of tetrapropylammonium hydroxide were added while stirring, and stirring was continued for 0.5h to completely dissolve and cool to room temperature. Then 9.92g of tetraethoxysilane-containing solution is slowly dripped into the solution and stirred for 12 hours at room temperature to obtain the ZSM-5 molecular sieve (one of MFI molecular sieves) membrane synthetic solution.
4) Transferring the porous carrier treated in the step 2) into a crystallization kettle containing a ZSM-5 molecular sieve membrane synthetic liquid, sealing, heating the crystallization kettle to 180 ℃, and carrying out heat preservation crystallization reaction for 72 hours. And after crystallization, taking out the carrier, repeatedly washing the carrier for several times by using deionized water until the pH value of the washing liquid is 7, and drying the carrier for 24 hours at 100 ℃ to obtain the ZSM-5 molecular sieve membrane.
5) Carrying out pervaporation test on the ZSM-5 molecular sieve membrane prepared in the step 4), wherein the permeation flux of the ZSM-5 molecular sieve membrane is 15.1 kg.m-2·h-1The alcohol-water separation selectivity was 200. The molecular sieve membrane prepared in comparative example 2 has a poor quality and many defects, so that the mixed solution passes through the membrane layer from the defect of small mass transfer resistance, resulting in very high permeation flux, but since the pores of the defect are larger than the kinetic diameter of the separated material, which itself does not have molecular sieving properties, all of water and ethanol can pass through the defect, resulting in poor selectivity.
Claims (10)
1. The preparation method for efficiently separating the ultrathin defect-free molecular sieve membrane is characterized by comprising the following steps of:
1) assembling a layered molecular sieve on the surface of a porous carrier;
2) treating the porous carrier treated in the step 1) in an acidic or alkaline solution to dissolve the layered molecular sieve to generate a structural infinitesimal layer;
3) and 2) crystallizing and synthesizing the porous carrier treated in the step 2) and the target molecular sieve membrane synthetic liquid to obtain the high-efficiency separation ultrathin defect-free molecular sieve membrane.
2. The method according to claim 1, wherein in step 1), the porous support has a sheet-like or tubular hollow structure.
3. The method of claim 1, wherein the layered molecular sieve in step 1) includes, but is not limited to, the following structure types of molecular sieves: CDO, MWW, FER, layered MFI, layered AFO or layered MOF molecular sieves.
4. The method according to claim 1, wherein the acidic or basic solution in step 2) is: an acidic or alkaline target molecular sieve membrane synthetic solution, or an alkali solution with the mass concentration of 0.5-30% or an acid solution with the mass concentration of 0.5-30%.
5. The preparation method according to claim 1, wherein the step 2) is specifically: soaking the porous carrier treated in the step 1) in an acidic or alkaline solution for 0.5-12 h.
6. The method according to claim 1 or 5, wherein the acidic or basic solution in step 2) is: an acidic or alkaline target molecular sieve membrane synthetic solution, or an alkali solution with the mass concentration of 0.5-30% or an acid solution with the mass concentration of 0.5-30%.
7. The preparation method according to claim 1 or 5, wherein in the step 3), the crystallization synthesis specifically comprises: reacting for 0.5-96h at 60-200 ℃.
8. The preparation method of claim 1 or 5, wherein the target molecular sieve membrane in step 3) is a molecular sieve membrane including but not limited to L TA, MFI, SOD, FAU, ZIF, CHA or MOF.
9. An efficient separation ultrathin defect-free molecular sieve membrane prepared by the preparation method of any one of claims 1 to 8.
10. The ultra-thin defect-free molecular sieve membrane of claim 9, wherein the membrane layer thickness is less than 1 micron, the membrane layer is uniform and has no obvious defect on the surface, the alcohol-water separation efficiency is higher than 10000, and the permeation flux of water is higher than 4 kg-m-2·h-1。
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