Template-free aluminiferous beta molecular sieve membrane, its rapid preparation method and application in organic dehydration

Abstract

The present application relates to the technical field of molecular sieve membrane material preparation and pervaporation separation technology, and provides a template-free aluminum-rich Beta molecular sieve membrane, a rapid preparation method thereof and application of the template-free aluminum-rich Beta molecular sieve membrane in organic matter dehydration. The synthesis method of the present application adopts oil bath heating or microwave heating, and the synthesis time of the Beta molecular sieve membrane is reduced by adding fluorine ions and seed crystals into the synthesis gel without organic template. By regulating the molar ratio of the synthesis gel, the distribution of aluminum elements in the molecular sieve framework is improved to enhance the hydrophilicity of the membrane surface and improve the pervaporation dehydration performance of the aluminum-rich Beta molecular sieve membrane. The preparation method of the present application can significantly reduce the membrane synthesis time, reduce energy consumption and improve the utilization efficiency of the reaction equipment, the whole preparation process is rapid and simple, the microstructure of the membrane can be accurately constructed under the condition of not adding organic template, and the high-hydrophilicity aluminum-rich Beta molecular sieve membrane with continuous and dense membrane layer and thin thickness is prepared.

Description

Technical Field

[0001] This invention relates to the field of molecular sieve membrane material preparation and pervaporation separation technology, and particularly to a template-free aluminum-rich Beta molecular sieve membrane, its rapid preparation method, and its application in organic dehydration. Background Technology

[0002] Beta zeolite is a high-silica zeolite composed of a three-dimensional twelve-membered ring pore structure. Its unique pore structure endows it with excellent thermal stability, high surface acidity, and excellent catalytic activity, and it has been widely used in the petrochemical industry. Due to its strong hydrophobicity, pure silica or high-silica Beta molecular sieve membranes are suitable for recovering important organic matter from wastewater systems with low organic content. In addition, by distributing a large amount of aluminum in the pure silica Beta zeolite framework, aluminum-rich Beta molecular sieve membranes can be obtained. Like other low Si / Al ratio molecular sieve membranes, aluminum-rich Beta molecular sieve membranes with excellent hydrophilicity also show great potential for dehydration of organic matter / water systems.

[0003] However, the preparation of well-crystallized and densely continuous Beta molecular sieve membranes remains a major challenge restricting their development in the field of organic solvent pervaporation separation. Over the past decade, research on the preparation of pure and high-silica Beta molecular sieve membranes in the presence of organic templates has attracted considerable attention. Zhang et al. ([J]. Cryst Growth Des, 2019, 19: 3166-3171.) synthesized dense high-silica Beta molecular sieve membranes on porous alumina supports using tetraethylammonium hydroxide as an organic template agent. For the separation of 1 wt% and 5 wt% n-butanol / water mixtures, the prepared membranes showed high molecular weight ratios of 1.45 and 1.05 kg m³, respectively. -2 h -1 The permeation flux and corresponding separation factors were 36.5 and 32.5, respectively. Oumi et al. ([J]. Sep Purif Technol, 2020, 247: 116934.) prepared hydrophobic pure silica Beta molecular sieve membranes by adding tetraethylammonium hydroxide to dilute synthetic gels. For a 1 wt% n-butanol / water mixture, it showed a permeation flux of 1.00 kg m -2 h -1 It boasts high permeation flux and a separation factor of 132. However, in practical applications, the use of expensive organic templates not only increases synthesis costs, but also, due to the difference in thermal expansion coefficients between the porous support and the zeolite membrane, removing the organic template from the zeolite framework may cause cracks in the membrane during the calcination step at higher temperatures. These cracks reduce the practical value of the molecular sieve membrane.

[0004] Compared to pure silicon and high-silica Beta zeolite membranes, alumina-rich Beta zeolite membranes are also synthesized via organic template routes. However, it is difficult to synthesize highly selective alumina-rich Beta zeolite crystal layers without organic templates. To date, there are few reports on template-free synthesis of alumina-rich Beta zeolite membranes. Zhang et al. ([J]. Chem Commun, 2014, 50:8834-8837) prepared preferentially (h0l) oriented Beta zeolite membranes at 413 K using a secondary growth method under template-free conditions, with a synthesis time of up to 5 days. Sakai et al. ([J]. Micropor Mesopor Mater, 2019, 284:360-365) reported the preparation of continuous Beta zeolite membrane layers at 393 K, but the synthesis time was as long as 7 days. The excessively long synthesis time greatly limits the preparation and application of alumina-rich Beta zeolite membranes.

[0005] The current preparation process of aluminum-rich Beta molecular sieve membranes suffers from several problems, including excessively long synthesis time, use of expensive organic template agents, poor membrane reproducibility, and poor pervaporation performance during organic dehydration. Exploring rapid preparation and excellent reproducibility of high-performance, template-free aluminum-rich Beta molecular sieve membranes with superior hydrophilicity remains the real challenge limiting their industrial application. Summary of the Invention

[0006] This invention aims to overcome at least one of the shortcomings and deficiencies of the prior art, and provides a method for rapidly preparing alumina-rich Beta molecular sieve membrane with strong surface hydrophilicity, thin membrane layer, and excellent dehydration performance on the surface of a porous alumina support by optimizing the microstructure of the membrane layer using F- and seed induction, and by synthesis method using oil bath or microwave heating. The objective of this invention is achieved based on the following technical solution: The first aspect of this invention provides a rapid method for preparing template-free, aluminum-rich Beta molecular sieve membranes, comprising the following steps: S1. Preparation of aluminum-rich Beta seed crystals: Add silicon source to alkaline solution and heat to dissolve, then add dropwise to aluminum source dissolved in water, age to obtain synthetic sol, then put into reaction vessel for hydrothermal crystallization, separate solid phase, dry to obtain aluminum-rich Beta seed crystals; S2, Seed loading: The aluminum-rich Beta seed crystals prepared in step S1 are dispersed in a solvent to prepare a seed crystal suspension. The seed crystal suspension is loaded onto the surface of a porous support by a vacuum coating method to load a uniform seed crystal layer, thus obtaining a seeded support. S3. Preparation of membrane synthesis sol: Using aluminum source, alkali source, silicon source, fluorine source and deionized water as raw materials, mix and stir to form a white suspension, age to obtain membrane synthesis sol; wherein, the aluminum source is sodium aluminate, the alkali source is sodium hydroxide, the fluorine source is sodium fluoride, and the molar ratio of the raw materials is expressed in the form of oxides as follows: Al2O3 / SiO2=0.01~0.05, NaF / SiO2=0.1~1, Na2O / SiO2=0.1~1.2, H2O / SiO2=10~80; S4. Preparation of aluminum-rich Beta molecular sieve membrane: 0.02wt% to 0.4wt% of aluminum-rich Beta seed crystals were added to the membrane synthesis sol obtained in step S3, along with the seeded support obtained in step S2. The mixture was placed in a reaction vessel and heated by microwave or oil bath for crystallization reaction at a temperature of 100 to 160°C for 8 to 27 hours. After crystallization, the membrane was washed until neutral and dried to obtain the aluminum-rich Beta molecular sieve membrane.

[0007] Oil bath heating uses thermally conductive oil as the heat transfer medium, offering advantages such as high heat transfer efficiency. Microwave heating relies on the absorption of microwaves by the heated object and their conversion into heat energy; due to its high-frequency characteristics, it allows for a rapid and uniform temperature rise. Therefore, this invention significantly improves the crystallization efficiency of aluminum-rich Beta molecular sieve membranes by employing either oil bath heating or microwave heating as crystallization methods. Simultaneously, it enhances this efficiency by adding seed crystals and F to the membrane synthesis gel. - Mineralizing agents, through dual induction, accelerate the crystallization rate of Beta molecular sieve membrane crystals, significantly shortening the synthesis time and effectively reducing the formation of pinholes or cracks in the membrane. The method of this invention yields a dense, aluminous Beta molecular sieve membrane with excellent hydrophilicity and interactive symbiotic structure.

[0008] Preferably, in step S1: The aging process involves aging at 35-95°C for 1-6 hours. The heating methods used in the hydrothermal crystallization include microwave heating or oil bath heating; The hydrothermal crystallization temperature is 110~160°C, and the time is 10~24h; The drying temperature is 40~110°C.

[0009] Preferably, the molar ratio of the raw materials for the aluminum-rich Beta seed crystals in step S1 is expressed in oxide form as: 10~80SiO2: Al2O3: 5~30Na2O: 0.5~5NaF: 200~1200H2O.

[0010] Preferably, the vacuum coating method in step S2 is as follows: one end of the porous support is sealed and the other end is connected to the vacuum pump pipeline. The connected porous support is placed in the seed crystal suspension, the vacuum pump is turned on, and the seed crystal is introduced to the surface of the porous support by the pressure difference.

[0011] Preferably, after turning on the vacuum pump, the porous support is placed in the seed crystal suspension for 10-60 seconds and then removed. The above process is repeated at least once.

[0012] Preferably, the porous support in step S2 includes a zirconia ceramic tube, an alumina ceramic tube, a stainless steel ceramic tube, or a hollow fiber ceramic tube; the average pore size of the porous support is 0.05~2.5 μm, and the porosity is 20~50%.

[0013] Preferably, in step S2: The solvent includes one or more of water, methanol, ethanol, and isopropanol; The concentration of the seed crystal suspension is 0.05~3wt%; The thickness of the seed layer is 0.4~5μm.

[0014] Preferably, the silicon source in step S3 includes one or more of the following: white carbon black, kaolin, silica sol, tetraethyl orthosilicate, and silica gel.

[0015] Preferably, in step S3: The aging process involves aging at a temperature of 40-90°C for 3-12 hours. In step S4: The drying temperature is 40~110°C.

[0016] A second aspect of the present invention is to provide a template-free aluminum-rich Beta molecular sieve membrane, prepared according to the above-described preparation method.

[0017] A third aspect of the present invention is to provide an application of a template-free aluminum-rich Beta molecular sieve membrane in the dehydration and separation of organic matter and water systems.

[0018] This invention can achieve at least one of the following beneficial effects: This invention systematically studies the crystallization process of aluminum-rich Beta molecular sieve membranes and the effects of Al2O3 / SiO2 and H2O / SiO2 ratios in the synthetic sol on membrane morphology and separation performance. By controlling the molar ratio of the synthetic gel, the distribution of aluminum in the molecular sieve framework is increased to enhance the hydrophilicity of the membrane surface and improve the pervaporation and dehydration performance of the aluminum-rich Beta molecular sieve membrane. The microstructure of the aluminum-rich Beta molecular sieve membrane crystals and the synthesis time of the Beta molecular sieve membrane are controlled by adjusting the fluoride content in the synthetic sol without organic template agents and the amount of inducing crystals added. This results in an aluminum-rich Beta molecular sieve membrane with strong hydrophilicity and high permeability selectivity. Furthermore, the synthesis time is significantly reduced by using microwave heating or oil bath heating methods. The synthesis methods are simple, efficient, and utilize the synthesis equipment effectively.

[0019] This invention provides a rapid method for preparing alumina-rich Beta molecular sieve membrane with high hydrophilicity and high pervaporation performance, reducing the synthesis time from the conventional 5-7 days to 6-22 hours. The method significantly reduces membrane synthesis time, energy consumption, and improves the utilization efficiency of reaction equipment; the entire preparation process is fast and simple. The microstructure of the membrane is precisely constructed without the addition of organic template agents, resulting in a continuous, dense, and relatively thin highly hydrophilic alumina-rich Beta molecular sieve membrane with an average thickness of 5-12 μm. The membrane layers exhibit exchange symbiosis and are free from defects such as crystal cracks and pores, making it suitable for pervaporation dehydration processes in organic systems such as butanol / water and ethanol / water.

[0020] This invention rapidly prepares aluminum-rich Beta molecular sieve membranes with good hydrophilicity and excellent pervaporation performance. Besides butanol / water and ethanol / water systems, the membranes prepared by this invention can also be applied to the dehydration processes of other organic mixtures such as alcohols and acetic acid / water. This invention solves the problems of long synthesis time and poor pervaporation performance of aluminum-rich Beta molecular sieve membranes, laying a practical and theoretical foundation for the industrial application of Beta molecular sieve membranes in the dehydration of butanol / water and ethanol / water systems. It also has broad application prospects in pervaporation dehydration and membrane reactor coupled catalytic reactions. Attached Figure Description

[0021] Figure 1 The XRD patterns of the alumina support and the prepared aluminum-rich Beta molecular sieve membrane used in the preferred embodiment of the present invention are shown. Figure 2 Surface electron micrograph of an aluminum-rich Beta molecular sieve membrane prepared according to a preferred embodiment of the present invention; Figure 3 A cross-sectional electron microscope image of an aluminum-rich Beta molecular sieve membrane prepared according to a preferred embodiment of the present invention; Figure 4Water contact angle diagram of the aluminum-rich Beta molecular sieve membrane prepared according to a preferred embodiment of the present invention; Figure 5 The pervaporation performance of the aluminum-rich Beta molecular sieve membrane prepared according to the preferred embodiment of the present invention for separating 90 wt% butanol / water solution under four temperature conditions: 45°C, 60°C, 75°C and 90°C is shown in the figure. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] Example 1 1. Preparation of aluminum-rich Beta seed crystals: Sodium hydroxide (alkali source) was dissolved in deionized water, followed by aluminum hydroxide (aluminum source). The mixture was heated until clear and then cooled to room temperature. Sodium silicate (silicon source) was added to boiling deionized water, and the mixture was cooled to room temperature after clarifying. The cooled aluminum source was then slowly added dropwise to the silicon source, and the mixture was vigorously stirred until completely mixed. Finally, sodium fluoride (fluorine source) dissolved in deionized water was added, and the mixture was vigorously stirred to form a white reactive sol. The molar ratio of the sol was 25SiO2: Al2O3: 15Na2O: 3.75NaF: 500H2O. The synthesized sol was aged at 65 °C for 4 h. After aging, the sol was poured into a stainless steel reactor lined with polytetrafluoroethylene (PTFE). The sealed stainless steel reactor was placed in an oil bath heater for reaction, and the mixture was crystallized at 140 °C for 18 h. After crystallization, the solid phase was separated, dried, and aluminum-rich Beta seed crystals were obtained.

[0024] 2. Seed crystal coating: The porous alumina ceramic tube produced by Guangdong Jiexi Lishun Company was used as the support for synthesizing the alumina-rich Beta molecular sieve membrane in this experiment. The inner and outer diameters of the support were 8 mm and 12 mm, respectively, the length was 5 cm, the porosity was approximately 35%, and the average pore size was approximately 500 nm. The support was hot-washed with 0.1 mol / L alkaline solution, then washed with boiling deionized water until neutral, and dried at 60 °C for 6 h before use.

[0025] 2g of aluminum-rich Beta seed crystals were ultrasonically dispersed in 198g of anhydrous ethanol solvent to prepare a 1 wt% seed crystal suspension. One end of an alumina support was sealed, and the other end was connected to a circulating water vacuum pump. The connected porous support was then immersed in the 1 wt% Beta seed crystal suspension. The vacuum pump was turned on, and the support was removed after 30 seconds. This process was repeated three times, using pressure difference to introduce the seed crystals onto the outer surface of the support. The average thickness of the coated seed layer was 2.5 μm. The coated support was then dried at 60°C for 1 hour for later use.

[0026] 3. Preparation of membrane synthesis sol: Sodium aluminate was used as the aluminum source, silica as the silicon source, sodium hydroxide as the alkali source, and sodium fluoride as the fluorine source. Sodium hydroxide was dissolved in deionized water, and silica was added under heating until completely dissolved. After cooling, the silica was added to the aluminum source aqueous solution, and finally, the fluorine source aqueous solution was added. The mixture was stirred to form a milky white reactive sol. The molar ratios of the sol were: Al₂O₃ / SiO₂ = 0.025, XF / SiO₂ = 0.6, Na₂O / SiO₂ = 0.3, and H₂O / SiO₂ = 25. The synthesized sol was aged at 50 °C for 8 h.

[0027] 4. Preparation of aluminum-rich Beta molecular sieve membranes: After the sol-gel for membrane synthesis was aged, the sol was poured into a stainless steel reactor, and 0.45 g (1.5 wt% of the sol weight) of aluminum-rich Beta seed crystals were added as an induction agent. Simultaneously, a support pre-coated with Beta seed crystals was vertically placed into the reactor. The sealed stainless steel reactor was placed in an oil bath heater for the reaction, and synthesis was carried out at 130 °C for 20 h. The synthesized membrane was repeatedly rinsed with deionized water to remove amorphous substances from the membrane surface and inner wall, as well as the alkali solution adsorbed in the support. After washing until neutral, it was dried at 60 °C for 6 h before use.

[0028] 5. Pervaporation Experiment Pervaporation experiments were conducted on the obtained alumina-rich Beta molecular sieve membranes to test their pervaporation performance (75 °C) in a butanol / water (90 / 10 wt%) system. The results are shown in Table 1 for MB-01 and MB-02. The pervaporation performance of the membranes is determined by the permeate flux. J and separation coefficient α Two parameters are used to represent this. Permeation flux. J This represents the total mass of substance that permeates through a unit area of ​​membrane per unit time, expressed in kg / m³. -2 h -1 Separation coefficient α Used to evaluate the efficiency of membrane separation. α = (Y N / Y W ) / (X N / XW ), where Y N With Y W X represents the mass percentage concentration of organic matter and water in the permeate, respectively. N With X W The values ​​represent the mass percentage concentrations of the two components in the feed solution. The contents of components A and B were determined using a Shimadzu GC-14C gas chromatograph.

[0029] The pre-synthesis support and the synthesized alumina-rich Beta molecular sieve membrane were characterized by XRD and scanning electron microscopy (SEM). The results showed that the molecular sieve membrane synthesized under optimized conditions was confirmed by XRD analysis to be a pure-phase Beta molecular sieve membrane (e.g., ...). Figure 1 As shown in the image), and from the scanning electron microscope image, a continuous and dense molecular sieve film layer can be seen formed on the alumina support, with a film thickness of approximately 5 mm (as shown in the image). Figure 2 and Figure 3 The molecular sieve crystals exhibit a typical Beta crystal morphology. Further water contact angle testing revealed that the Beta molecular sieve membrane synthesized under optimized conditions had a water contact angle of 64.42° (e.g., ...). Figure 4 This indicates that the surface of the synthesized membrane has strong hydrophilicity.

[0030] Table 1

[0031] Example 2 The raw materials, proportions, and operating steps for the membrane synthesis sol were the same as in Example 1, except that the synthesis temperature was increased to 140 °C and the crystallization time was adjusted to 16 h.

[0032] The synthesized molecular sieve membranes were used for pervaporation experiments and characterization. Their pervaporation performance in a butanol / water (90 / 10 wt%) system was tested (75 °C). The experimental results are shown in Table 2 for MB-03 and MB-04.

[0033] Table 2

[0034] Example 3 The operation was the same as in Example 2, except that silica sol (TM-40) was used as the silicon source in the synthesis raw materials, and the other raw materials were the same as in Example 2.

[0035] The synthesized molecular sieve membranes were used for pervaporation experiments and characterization. Their pervaporation performance in a butanol / water (90 / 10 wt%) system was tested (75 °C). The experimental results are shown in Table 3 for MB-5 and MB-6.

[0036] Table 3

[0037] Example 4 The raw materials and operating steps for membrane synthesis sol were the same as in Example 2, except that the Al2O3 / SiO2 ratio was adjusted to 0.03, and the rest were the same as in Example 2.

[0038] The synthesized molecular sieve membranes were used for pervaporation experiments and characterization. Their pervaporation performance in a butanol / water (90 / 10 wt%) system was tested (75 °C). The experimental results are shown in Table 4 for MB-7 and MB-8.

[0039] Table 4

[0040] Example 5 The raw materials and operating steps for membrane synthesis sol were the same as in Example 2, except that the Na2O / SiO2 ratio was adjusted to 0.35, and the rest were the same as in Example 2.

[0041] The synthesized molecular sieve membranes were used for pervaporation experiments and characterization. Their pervaporation performance in a butanol / water (90 / 10 wt%) system was tested (75 °C). The experimental results are shown in Table 5 for MB-9 and MB-10.

[0042] Table 5

[0043] Example 6 The raw materials and operating steps for membrane synthesis sol are the same as in Example 2, except that the H2O / SiO2 ratio is adjusted to 20, and the rest is the same as in Example 2.

[0044] The synthesized molecular sieve membranes were used for pervaporation experiments and characterization. Their pervaporation performance in a butanol / water (90 / 10 wt%) system was tested (75 °C). The experimental results are shown in Table 6 for MB-11 and MB-12.

[0045] Table 6

[0046] Example 7 A porous alumina ceramic tube (outer diameter 12 mm, inner diameter 10 mm, porosity 35%, average pore size 1.3 μm, length 5 cm) manufactured by Nikkato Corporation of Japan was used as the carrier for the synthesis of the alumina-rich Beta molecular sieve membrane. The support was pretreated by alkaline hot cleaning and then dried. A layer of alumina-rich Beta molecular sieve seed crystals was then coated using a vacuum coating method. The synthesis ratio and preparation conditions were the same as in Example 2.

[0047] The synthesized molecular sieve membranes were used for pervaporation experiments and characterization. Their pervaporation performance in a butanol / water (90 / 10 wt%) system was tested (75 °C). The experimental results are shown in Table 7 for MB-13 and MB-14.

[0048] Table 7

[0049] Example 8 A porous stainless steel tube (outer diameter 12 mm, inner diameter 10 mm, porosity 48%, average pore size 1.8 μm, length 5 cm) manufactured by Pall Corporation, USA, was used as the carrier for the synthesis of the alumina-rich Beta molecular sieve membrane. The support was pretreated with alkaline hot cleaning and then dried. A layer of alumina-rich Beta molecular sieve seed crystals was then coated using a vacuum coating method. The synthesis ratio and preparation conditions were the same as in Example 2.

[0050] The synthesized molecular sieve membranes were used for pervaporation experiments and characterization. Their pervaporation performance in a butanol / water (90 / 10 wt%) system was tested (75 °C). The experimental results are shown in Table 8 for MB-15 and MB-16.

[0051] Table 8

[0052] Example 9 The raw materials, proportions, and operating steps for the membrane synthesis sol are the same as in Example 1, except that the heating method is changed to microwave heating.

[0053] The synthesized molecular sieve membranes were used for pervaporation experiments and characterization. Their pervaporation performance in a butanol / water (90 / 10 wt%) system was tested (75 °C). The experimental results are shown in Table 9 for MB-17 and MB-18.

[0054] Table 9

[0055] Example 10 Applications of aluminum-rich Beta molecular sieve membranes.

[0056] The aluminum-rich Beta molecular sieve membrane synthesized under the same conditions as in Example 2 was applied to ethanol / water and acetic acid / water systems, respectively, to investigate its pervaporation performance. The results are shown in Table 10.

[0057] Table 10

[0058] The results showed that, under the same operating procedures, when sodium aluminate was used as the aluminum source, silica as the silicon source, sodium hydroxide as the alkali source, and sodium fluoride as the fluorine source, and the ratios Al₂O₃ / SiO₂ were 0.025, NaF / SiO₂ = 0.6, Na₂O / SiO₂ = 0.3, and H₂O / SiO₂ = 25, and the synthesized sol was aged at 50 °C for 8 h, followed by the addition of 1.5 wt% aluminum-rich Beta seed crystals as an induction agent, and crystallization was carried out using an oil bath heating method at a synthesis temperature of 140 °C and a crystallization time of 16 h, and using porous alumina ceramic tubes from Guangdong Jiexi Lishun Company as the support, the synthesized aluminum-rich Beta molecular sieve membrane exhibited the best pervaporation performance. When used in a butanol / water system, at 75 °C and a feed-side butanol concentration of 90 wt%, the average permeation flux was 3.0 kg m³. -2 h -1 The separation coefficient is above 10,000.

[0059] Example 11 Applications of aluminum-rich Beta molecular sieve membranes.

[0060] The alumina-rich Beta molecular sieve membrane prepared under the conditions of Example 2 was applied to the separation of 90 wt% butanol / water solution at four temperature conditions: 45°C, 60°C, 75°C, and 90°C. Its pervaporation performance was investigated, and the results are as follows: Figure 5 As shown in the figure. The results indicate that the synthesized aluminum-rich Beta molecular sieve membrane exhibited excellent separation performance in the butanol dehydration experiment under four different temperature conditions, demonstrating its promising prospects for industrial application.

[0061] Comparative Example 1 The operation was the same as in Example 2, except that potassium hydroxide was used as the alkali source and potassium fluoride as the fluorine source in the synthesis raw materials, and the other raw materials were the same as in Example 2.

[0062] The synthesized molecular sieve membranes were used for pervaporation experiments and characterization. Their pervaporation performance in a butanol / water (90 / 10 wt%) system was tested (75 °C). The experimental results are shown in Table 11 for MB-19 and MB-20.

[0063] Table 11

[0064] Comparative Example 2 The operation was the same as in Example 2, except that cesium hydroxide was used as the alkali source and cesium fluoride as the fluorine source in the synthesis raw materials, and the other raw materials were the same as in Example 2.

[0065] The synthesized molecular sieve membranes were used for pervaporation experiments and characterization. Their pervaporation performance in a butanol / water (90 / 10 wt%) system was tested (75 °C). The experimental results are shown in Table 12 for MB-21 and MB-22.

[0066] Table 12

[0067] Comparative Example 3 The operation was the same as in Example 2, except that aluminum isopropoxide was used as the aluminum source in the synthesis raw materials, and the other raw materials were the same as in Example 2.

[0068] The synthesized molecular sieve membranes were used for pervaporation experiments and characterization. Their pervaporation performance in a butanol / water (90 / 10 wt%) system was tested (75 °C). The experimental results are shown in Table 13 for MB-23 and MB-24.

[0069] Table 13

[0070] Comparative Example 4 The raw materials, proportions, and operating steps for the membrane synthesis sol are the same as in Example 2, except that the heating method is changed to oven heating.

[0071] The synthesized molecular sieve membranes were used for pervaporation experiments and characterization. Their pervaporation performance in a butanol / water (90 / 10 wt%) system was tested (75 °C). The experimental results are shown in Table 14 for MB-25 and MB-26.

[0072] Table 14

[0073] Comparative Example 5 The raw materials, proportions, and operating steps for the membrane synthesis sol were the same as in Example 1, except that the heating method was changed to oven heating and the crystallization time was adjusted to 48 h.

[0074] The synthesized molecular sieve membranes were used for pervaporation experiments and characterization. Their pervaporation performance in a butanol / water (90 / 10 wt%) system was tested (75 °C). The experimental results are shown in MB-27 and MB-28 in Table 15.

[0075] Table 15

[0076] Comparative Examples 4 and 5 illustrate that using oven heating requires a significantly extended crystallization time to obtain molecular sieve membranes with good pervaporation performance, while the method of the present invention can significantly shorten the synthesis time.

[0077] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A rapid preparation method for template-free aluminum-rich Beta molecular sieve membranes, characterized in that, Includes the following steps: S1. Preparation of aluminum-rich Beta seed crystals: Add silicon source to alkaline solution and heat to dissolve, then add dropwise to aluminum source dissolved in water, age to obtain synthetic sol, then put into reaction vessel for hydrothermal crystallization, separate solid phase, dry to obtain aluminum-rich Beta seed crystals; S2, Seed loading: The aluminum-rich Beta seeds prepared in step S1 are dispersed in a solvent to prepare a seed suspension. The seed suspension is loaded onto the surface of a porous support by a vacuum coating method to form a uniform seed layer, thus obtaining a seeded support. The vacuum coating method is as follows: one end of the porous support is sealed, and the other end is connected to a vacuum pump pipeline. The connected porous support is placed in the seed suspension, and the vacuum pump is turned on. The pressure difference is used to introduce the seed onto the surface of the porous support. S3. Preparation of membrane synthesis sol: Using aluminum source, alkali source, silicon source, fluorine source and deionized water as raw materials, mix and stir to form a white suspension, age to obtain membrane synthesis sol; wherein, the aluminum source is sodium aluminate, the alkali source is sodium hydroxide, the fluorine source is sodium fluoride, and the molar ratio of the raw materials is expressed in the form of oxides as follows: Al2O3 / SiO2=0.01~0.05, NaF / SiO2=0.1~1, Na2O / SiO2=0.1~1.2, H2O / SiO2=10~80; S4. Preparation of aluminum-rich Beta molecular sieve membrane: 0.02wt% to 0.4wt% of aluminum-rich Beta seed crystals were added to the membrane synthesis sol obtained in step S3, along with the seeded support obtained in step S2. The mixture was placed in a reaction vessel and subjected to a crystallization reaction by microwave heating or oil bath heating at a temperature of 100 to 160°C for 8 to 27 hours. After crystallization, the membrane was washed until neutral and dried to obtain the aluminum-rich Beta molecular sieve membrane.

2. The rapid preparation method of a template-free aluminum-rich Beta molecular sieve membrane according to claim 1, characterized in that, In step S1: The aging process involves aging at 35-95°C for 1-6 hours. The heating methods used in the hydrothermal crystallization include microwave heating or oil bath heating; The hydrothermal crystallization temperature is 110~160°C, and the time is 10~24h; The drying temperature is 40~110°C.

3. The rapid preparation method of a template-free aluminum-rich Beta molecular sieve membrane according to claim 1, characterized in that, The molar ratio of the raw materials for the aluminum-rich Beta seed crystals in step S1 is expressed in oxide form as follows: 10~80 SiO2: Al2O3: 5~30 Na2O: 0.5~5 NaF: 200~1200 H2O.

4. A rapid preparation method for a template-free aluminum-rich Beta molecular sieve membrane according to claim 1, characterized in that, The porous support in step S2 includes zirconia ceramic tube, alumina ceramic tube, stainless steel ceramic tube or hollow fiber ceramic tube; the average pore size of the porous support is 0.05~2.5 μm and the porosity is 20~50%.

5. The rapid preparation method of a template-free aluminum-rich Beta molecular sieve membrane according to claim 1, characterized in that, In step S2: The solvent includes one or more of water, methanol, ethanol, and isopropanol; The concentration of the seed crystal suspension is 0.05~3wt%; The thickness of the seed layer is 0.4~5μm.

6. The rapid preparation method of a template-free aluminum-rich Beta molecular sieve membrane according to claim 1, characterized in that, The silicon source mentioned in step S3 includes one or more of the following: white carbon black, kaolin, silica sol, tetraethyl orthosilicate, and silica gel.

7. The rapid preparation method of a template-free aluminum-rich Beta molecular sieve membrane according to claim 1, characterized in that, In step S3: The aging process involves aging at 40-90°C for 3-12 hours. In step S4: The drying temperature is 40~110°C.

8. A template-free aluminum-rich Beta molecular sieve membrane, characterized in that, Prepared by the rapid preparation method according to any one of claims 1-7.

9. The application of the template-free aluminum-rich Beta molecular sieve membrane according to claim 8 in the dehydration and separation of organic matter and water systems.

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