Template-free rapid synthesis of suz-4 zeolite membrane and application in dehydration of butanol

Abstract

The present application relates to the technical field of synthesis of new porous membrane material and dehydration separation of organic solvent, and provides a template-free SUZ-4 molecular sieve membrane static rapid synthesis method and application thereof in butanol dehydration. The synthesis method of the present application is static heating, and the synthesis sol is added with crystal seeds for induction or the alkalinity of the reaction solution is adjusted for synthesis of the SUZ-4 molecular sieve membrane. The synthesis method of the present application does not use expensive organic templates, can greatly save the synthesis cost, avoids possible cracks of the membrane layer and pollution of the environment in the calcination process for removing the organic templates, and meanwhile, the membrane synthesis time of the present application is short, the equipment is simple, energy consumption is reduced, the whole synthesis process is rapid and simple, and the interactive symbiotic dense high-performance SUZ-4 molecular sieve membrane is prepared under the condition of no addition of organic templates.

Description

Technical Field

[0001] This invention relates to the fields of novel porous membrane material synthesis and organic solvent dehydration and separation technology, and particularly to a method for rapid synthesis of SUZ-4 molecular sieve membrane without template agent by static setting and its application in butanol dehydration. Background Technology

[0002] SUZ-4 molecular sieve is a novel type of molecular sieve with a three-dimensional pore structure composed of five-, six-, eight-, and ten-membered rings, with the largest ten-membered ring having a pore size of 0.52 nm × 0.46 nm. Its unique pore structure has been widely used in adsorption separation and catalysis.

[0003] Pervaporation membrane separation technology has advantages such as separation process not being limited by gas-liquid equilibrium, simple equipment operation, and energy saving. It is particularly suitable for the separation of azeotropic or near-boiling mixtures, gas separation, and membrane reactors. The most crucial factor is the selection of membrane material. Molecular sieve membranes are considered excellent membrane materials for pervaporation membrane separation technology due to their excellent pore structure and good thermal stability. SUZ-4 molecular sieve membranes, formed by the interactive symbiosis of SUZ-4 molecular sieves on the support surface, also have excellent application prospects in the field of organic matter separation due to their unique pore structure. Worathanakul et al. ([J]. International Journal of Chemical and Biological Engineering, 2008, 1(3): 131-135.) used tetraethylammonium hydroxide as a template agent and prepared SUZ-4 molecular sieve membranes on mullite supports for the first time through a coating method. Zuo Yameng et al. ([J]. Journal of Liaoning University of Engineering and Technology, 2019, 38(2): 168-173.) prepared SUZ-4 molecular sieve membranes with a thickness of approximately 10 micrometers by dynamic hydrothermal crystallization on tubular alumina supports at 150℃ for 24 h. Similarly, the reaction sol system contained the organic template agent tetraethylammonium hydroxide. Under optimal conditions, the membrane synthesized at 50℃ exhibited a permeation flux of 0.42 kg m³ when separating 90 wt% ethyl acetate / 10 wt% aqueous solution. -2 h -1 The separation factor reached 286. Xu Zhenliang et al. ([Z]. CN113634138B.) disclosed a method for removing methanol from a hollow fiber outer wall SUZ-4 molecular sieve pervaporation membrane using ethyl ammonium hydroxide as an organic template agent via dynamic hydrothermal synthesis. When the crystallization time was 24 h, the selective separation factor of the membrane for water in a 10 wt.% methanol-methyl methacrylate system at 50 °C exceeded 10000, and the flux reached 3.83 kg m³. -2 h -1 .

[0004] Currently, the synthesis of SUZ-4 molecular sieve membranes typically employs organic templates and a rotational dynamic hydrothermal synthesis method. There are no reports of synthesizing SUZ-4 molecular sieve membranes without organic templates or using a static synthesis process. However, the use of expensive organic templates not only significantly increases costs but also easily causes membrane cracking and environmental pollution during calcination. Furthermore, the rotational dynamic hydrothermal synthesis complicates the reaction equipment, further limiting the practical application value of SUZ-4 molecular sieve membranes. In addition, there are currently no reports on the application of SUZ-4 molecular sieve membranes in the dehydration and separation of butanol solutions. Summary of the Invention

[0005] The current synthesis of SUZ-4 molecular sieve membranes faces several challenges, including the use of expensive organic templates, complex equipment due to rotational dynamic synthesis, and long synthesis times. Exploring a static, rapid synthesis method for template-free SUZ-4 molecular sieve membranes with excellent permeation selectivity is crucial for their practical application.

[0006] This invention aims to overcome at least one of the shortcomings and deficiencies of the prior art, and provides a synthesis method for rapidly synthesizing SUZ-4 molecular sieve membranes with high water permeability selectivity by using ball milling seed induction and alkalinity adjustment to obtain a high crystallization rate, and by heating in a static oven or static oil bath. This invention is achieved based on the following technical solutions:

[0007] The first aspect of this invention provides a method for the rapid, static synthesis of template-free SUZ-4 molecular sieve membranes, comprising the following steps:

[0008] S1. Preparation of template-free SUZ-4 seed crystals: Aluminum source and alkali source are mixed and dissolved in water, then silicon source is added, stirred and aged to obtain a reaction sol, then hydrothermal crystallization is performed, centrifugation is used to separate the solid phase, and the solid phase is dried and ground to obtain template-free SUZ-4 molecular sieve seed crystals.

[0009] S2, Seed layer loading of support: The template-free SUZ-4 molecular sieve seed crystals prepared in step S1 are ground into crystals with a particle size of 5 micrometers to 20 micrometers, and then ultrasonically dispersed in a solvent to prepare a seed crystal suspension. The seed crystals are uniformly loaded on the outer surface of the porous support by hot impregnation method to obtain a seeded support.

[0010] Preparation of S3 and SUZ-4 membrane reaction solutions: Using silicon source, aluminum source, alkali source and ultrapure water as raw materials, they are mixed and stirred to form a milky white suspension, aged, and the membrane reaction solution is obtained; wherein, the alkali source is potassium hydroxide, and the molar ratio of the raw materials is expressed in the form of oxides as follows: H2O / SiO2 = 5~45, KOH / SiO2 = 0.4~0.8, Al2O3 / SiO2 = 0.03~0.09;

[0011] S4. Preparation of template-free SUZ-4 membrane: The template-free SUZ-4 seed crystals prepared in step S1 are added to the reaction solution obtained in step S3 at 0.01wt% to 0.2wt% of the amount of the synthetic sol, and the seeded support obtained in step S2 is added. The mixture is placed in a reaction vessel and subjected to a static heating reaction at a temperature of 120 to 160°C for 8 to 24 hours. After crystallization, the membrane is washed with running water until neutral and dried to obtain a template-free SUZ-4 molecular sieve membrane.

[0012] Smaller molecular sieve seed crystals obtained after ball milling often exhibit better crystallization activity, significantly accelerating the crystallization rate. Furthermore, controlling the alkalinity (KOH / SiO2 = 0.4–0.8) increases the solubility of silicon and aluminum sources, significantly reducing the degree of polymerization of aluminosilicates, thereby accelerating crystal nucleation, shortening the induction period, and ultimately improving the crystallization rate. However, further increasing the alkalinity beyond 0.8 easily leads to the formation of impurity phases. Therefore, this invention significantly improves the crystallization efficiency of template-free SUZ-4 molecular sieve membranes by employing ball milling seed induction and alkalinity adjustment. The static heating crystallization method not only simplifies equipment and operation but also shortens the crystallization time. This invention yields a dense SUZ-4 molecular sieve membrane with excellent pervaporation performance through its simple method.

[0013] Preferably, the molar ratio of the raw materials for the template-free SUZ-4 seed crystals in step S1 is expressed in oxide form as: 5-40 SiO2:Al2O3:2-16 KOH:100-900 H2O.

[0014] Preferably, in step S1:

[0015] The aging process involves aging at 30–70°C for 4–24 hours.

[0016] The heating methods used in the hydrothermal crystallization include static oven heating or static oil bath heating;

[0017] The hydrothermal crystallization temperature is 120–180°C, and the time is 12–26 hours.

[0018] Preferably, the hot impregnation in step S2 specifically involves sealing both ends of the porous support, placing it in a programmable oven at a temperature of 60°C to 120°C and heating it for 10 to 90 minutes, then quickly removing it and immersing it in a seed crystal suspension, using the temperature and pressure difference to introduce the seed crystal onto the outer surface of the porous support.

[0019] Preferably, the porous support in step S2 includes an alumina ceramic tube, a stainless steel tube, a zirconia ceramic tube, a silica tube, or a mullite tube; the average pore size of the porous support is 0.01–2 μm, and the porosity is 15–45%.

[0020] Preferably, in step S2:

[0021] The solvent includes one or more of water, ethanol, acetone, and acetic acid;

[0022] The concentration of the seed crystal suspension is 0.02–1.5 wt%.

[0023] The thickness of the seed layer is 0.2–7 μm.

[0024] Preferably, in step S3: the silicon source is silica sol, preferably one or two of HS-40 and AS-40, and the aluminum source includes one or more of sodium aluminate, aluminum isopropoxide, aluminum nitrate, and aluminum sulfate.

[0025] Preferably, in step S3: the aging is carried out in a water bath at a temperature of 10 to 60°C for 4 to 16 hours.

[0026] A second aspect of the present invention provides a template-free SUZ-4 molecular sieve membrane, prepared according to the above-described static rapid synthesis method.

[0027] A third aspect of the present invention provides an application of a template-free SUZ-4 molecular sieve membrane in the dehydration and separation of butanol / water systems.

[0028] This invention can achieve at least one of the following beneficial effects:

[0029] This invention systematically studies the growth process of SUZ-4 molecular sieve membrane crystals under template-free conditions, as well as the effects of seed induction and sol alkalinity on membrane morphology and pervaporation performance. By controlling the sol alkalinity and the amount of seed induction added, the morphology of SUZ-4 molecular sieve membrane crystals can be controlled and the crystallization time of SUZ-4 molecular sieve membranes can be shortened, resulting in SUZ-4 molecular sieve membranes with excellent dehydration performance. Furthermore, the production equipment and process flow are simplified by using a static heating crystallization method. The synthesis method is simple and easy to control, significantly reducing equipment requirements.

[0030] This invention provides a rapid method for preparing template-free SUZ-4 molecular sieve membranes with excellent dehydration performance. This method eliminates the need for expensive organic templates and complex dynamic synthesis equipment, significantly reducing synthesis costs and avoiding potential problems such as membrane cracking and environmental pollution during the calcination process for removing organic templates. The synthesis time is also significantly reduced to 8–24 hours. The equipment is simple and energy-efficient, and the entire synthesis process is rapid and convenient. This method produces high-performance SUZ-4 molecular sieve membranes with interconnected and dense growth without the addition of organic templates. This invention is the first to achieve the preparation of template-free SUZ-4 molecular sieve membranes. Under static crystallization conditions without the addition of organic templates, the microstructure of the membrane layer is controllably constructed, resulting in a highly selective SUZ-4 molecular sieve membrane with interconnected growth. The synthesized template-free SUZ-4 molecular sieve membrane has an average thickness of 6–20 μm, is continuous, dense, and defect-free, and is suitable for pervaporation dehydration processes using organic solvents such as butanol / water.

[0031] The preparation method of this invention can significantly reduce the cost of membrane synthesis and improve the pervaporation performance of the membrane. The entire synthesis process is convenient and rapid. The SUZ-4 molecular sieve membrane prepared by this invention has excellent pervaporation dehydration performance and good organic matter selective sieving performance, realizing the application of SUZ-4 molecular sieve membrane in butanol dehydration. This invention solves the problems of using expensive organic template agents, excessively long crystallization time in static synthesis methods, and poor membrane reproducibility of SUZ-4 molecular sieve membranes. It provides theoretical and practical guidance for the industrial application of SUZ-4 molecular sieve membranes in butanol / water and other systems for dehydration, and has broad application value in pervaporation dehydration, separation of mixed organic matter, and other fields. Attached Figure Description

[0032] Figure 1 The XRD patterns of the alumina support and the synthesized template-free SUZ-4 molecular sieve membrane used in the preferred embodiment of the present invention are shown below.

[0033] Figure 2 Electron micrograph of template-free SUZ-4 seed crystals prepared according to a preferred embodiment of the present invention;

[0034] Figure 3 The particle size distribution diagram of template-free SUZ-4 seed crystals prepared according to a preferred embodiment of the present invention;

[0035] Figure 4 A surface electron microscope image of a template-free SUZ-4 molecular sieve membrane prepared according to a preferred embodiment of the present invention;

[0036] Figure 5 A cross-sectional electron microscope image of the template-free SUZ-4 molecular sieve membrane prepared according to a preferred embodiment of the present invention. Detailed Implementation

[0037] 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.

[0038] Example 1

[0039] 1. Preparation of seed crystals without template agent SUZ-4:

[0040] Sodium aluminate (aluminum source) was dissolved in deionized water, and potassium hydroxide (alkali source) was added and mixed. The mixture was then cooled to room temperature, and silicon sol (silicon source) HS-40 was added and stirred until homogeneous, yielding a white reaction solution. The molar ratio of the reaction solution was 1 SiO2:0.05 Al2O3:0.48 KOH:25 H2O. The synthesized sol was aged at 50℃ for 12 hours. After sol aging, the reaction solution was poured into a stainless steel reactor lined with polytetrafluoroethylene (PTFE). The reactor was then placed in a conventional controlled oven for crystallization at 150℃ for 28 hours. After crystallization, the solid phase was separated by centrifugation, dried, and ground to obtain SUZ-4 seed crystals.

[0041] 2. Support seed layer loading:

[0042] The support used in this experiment was a small-pore alumina ceramic tube produced by Guangdong Jiexi Lishun Company, which served as the carrier for the synthesis of template-free SUZ-4 molecular sieve membranes. The outer and inner diameters of this support were 12 mm and 8 mm, respectively, with an experimental length of 8 cm. The porosity was approximately 36%, and the average pore size was approximately 50 nm. The support was cleaned with 0.05 mol / L nitric acid solution, then rinsed with deionized water until neutral, and finally dried for later use.

[0043] 0.5 g of SUZ-4 seed crystals were ultrasonically dispersed in 99.5 g of deionized water to prepare a 0.5 wt% seed crystal suspension. The alumina support was sealed at both ends and placed in a controlled oven at 100 °C for 50 min. It was then quickly removed and immersed in the seed crystal suspension. After 30 s, the support was slowly removed and placed back into the oven for heating. This process was repeated twice. The temperature and pressure differences were used to introduce the seed crystals onto the outer surface of the porous support. Excess seed crystals were wiped away with a cotton swab, resulting in a seed crystal layer with an average thickness of 3 μm. The loaded support was then dried at 80 °C for 30 min for later use.

[0044] 3. Preparation of membrane synthesis solution:

[0045] Using silica sol HS-40 as the silicon source, sodium aluminate as the aluminum source, and potassium hydroxide as the alkali source, the sodium aluminate source was first dissolved in deionized water, and then the potassium hydroxide source was added and mixed. After cooling to room temperature, the silica sol HS-40 source was added and mixed thoroughly to obtain a white reaction solution. The molar ratio of the sol was: Al₂O₃ / SiO₂ = 0.05, KOH / SiO₂ = 0.45, H₂O / SiO₂ = 25. The synthesized sol was aged in a water bath at 45℃ for 12 hours.

[0046] 4. Preparation of template-free SUZ-4 molecular sieve membranes:

[0047] After the membrane reaction solution has aged, it is poured into a stainless steel reactor. 1.5 g (0.5 wt% of the sol weight) of ball-milled SUZ-4 seed crystals are added to the sol as an induction agent. Simultaneously, a support pre-coated with SUZ-4 seed crystals is vertically placed into the reactor. The sealed stainless steel reactor is placed in a conventional oven for static reaction at 150°C for 24 hours. The crystallized membrane is repeatedly rinsed with deionized water until neutral and then dried at 50°C for 4 hours before use.

[0048] 5. Pervaporation performance test

[0049] Pervaporation experiments were conducted on the obtained template-free SUZ-4 molecular sieve membranes to test their pervaporation performance (75℃) in a butanol / water (90 / 10wt%) system. The results are shown in Table 1 for SU-01 and SU-02. The pervaporation performance of the membranes is represented by two parameters: permeate flux J and separation coefficient α. Permeate flux J represents the total mass of material permeating through a unit area of ​​the membrane per unit time, expressed in kg / m³. -2 h -1 The separation coefficient α is used to evaluate the efficiency of membrane separation. α = (Y O / Y H ) / (X O / X H ), where Y O With Y H X represents the mass percentage concentration of organic matter and water in the permeate, respectively. O With X H 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-2014C gas chromatograph.

[0050] The support before synthesis and the template-free SUZ-4 molecular sieve membrane after synthesis were characterized by XRD. The results showed that the membrane synthesized under the optimized conditions was a pure-phase SUZ-4 molecular sieve membrane (e.g., Figure 1As shown). Characterization of the synthesized SUZ-4 seed crystals and the prepared film using scanning electron microscopy (SEM) revealed that the synthesized seed crystals were typical SUZ-4 strip-shaped crystals (as shown). Figure 2 Its particle size is quite uniform, approximately 10–100 μm (e.g., Figure 3 Meanwhile, SEM images show that SUZ-4 crystals formed an alternating, continuous molecular sieve film layer on the alumina support, with a film thickness of approximately 10 μm (e.g., Figure 4 and Figure 5 The molecular sieve crystals have a typical SUZ-4 crystal morphology.

[0051] Table 1

[0052]

[0053] Example 2

[0054] The raw materials, proportions, and operating steps for the membrane synthesis sol were the same as in Example 1, except that the crystallization time of the synthesized membrane was adjusted to 20 hours.

[0055] The synthesized molecular sieve membranes were used for pervaporation experiments and characterization. Their pervaporation performance in a butanol / water (90 / 10wt%) system was tested (75℃). The experimental results are shown in Table 2 for SU-03 and SU-04.

[0056] Table 2

[0057]

[0058] The results showed that, under the same operating procedures, the SUZ-4 molecular sieve membrane synthesized with a crystallization time of 20 h exhibited the best pervaporation performance. When used in a butanol / water system at 75 °C and a butanol concentration of 90 wt%, it achieved an average permeation flux of 1.6 kg m³ / s. -2 h -1 The separation coefficient is above 12500.

[0059] Example 3

[0060] 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 30, and the rest is the same as in Example 2.

[0061] The synthesized molecular sieve membranes were used for pervaporation experiments and characterization. Their pervaporation performance in a butanol / water (90 / 10wt%) system was tested (75℃). The experimental results are shown in Table 3 for SU-05 and SU-06.

[0062] Table 3

[0063]

[0064]

[0065] Example 4

[0066] The raw materials and operating steps for membrane synthesis sol were the same as in Example 2, except that the KOH / SiO2 ratio was adjusted to 0.40, and the rest were the same as in Example 2.

[0067] The synthesized molecular sieve membranes were used for pervaporation experiments and characterization. Their pervaporation performance in a butanol / water (90 / 10wt%) system was tested (75℃). The experimental results are shown in Table 4 for SU-07 and SU-08.

[0068] Table 4

[0069]

[0070] Example 5

[0071] The raw materials and operating steps for membrane synthesis sol were the same as in Example 2, except that the KOH / SiO2 ratio was adjusted to 0.5, and the rest were the same as in Example 2.

[0072] The synthesized molecular sieve membranes were used for pervaporation experiments and characterization. Their pervaporation performance in a butanol / water (90 / 10wt%) system was tested (75℃). The experimental results are shown in Table 5 for SU-09 and SU-10.

[0073] Table 5

[0074]

[0075] Example 6

[0076] The raw materials and operating steps for membrane synthesis sol were the same as in Example 2, except that the KOH / SiO2 ratio was adjusted to 0.6, and the rest were the same as in Example 2.

[0077] The synthesized molecular sieve membranes were used for pervaporation experiments and characterization. Their pervaporation performance in a butanol / water (90 / 10wt%) system was tested (75℃). The experimental results are shown in Table 6 for SU-11 and SU-12.

[0078] Table 6

[0079]

[0080] Example 7

[0081] The raw materials and operating steps for membrane synthesis sol are the same as in Example 2, except that the synthesis temperature is adjusted to 160℃, and everything else is the same as in Example 2.

[0082] The synthesized molecular sieve membranes were used for pervaporation experiments and characterization. Their pervaporation performance in a butanol / water (90 / 10wt%) system was tested (75℃). The experimental results are shown in Table 7 for SU-13 and SU-14.

[0083] Table 7

[0084]

[0085] Example 8

[0086] The raw materials and operating steps for membrane synthesis sol were the same as in Example 2, except that the synthesis time was adjusted to 16 hours. Everything else was the same as in Example 2.

[0087] The synthesized molecular sieve membranes were used for pervaporation experiments and characterization. Their pervaporation performance in a butanol / water (90 / 10wt%) system was tested (75℃). The experimental results are shown in Table 8 for SU-15 and SU-16.

[0088] Table 8

[0089]

[0090] Example 9

[0091] The procedure was the same as in Example 2, except that silica sol AS-40 was used as the silicon source in the synthesis, and the other raw materials were the same as in Example 2.

[0092] The synthesized molecular sieve membranes were used for pervaporation experiments and characterization. Their pervaporation performance in a butanol / water (90 / 10wt%) system was tested (75℃). The experimental results are shown in Table 9 for SU-17 and SU-18.

[0093] Table 9

[0094]

[0095] Example 10

[0096] 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.

[0097] The synthesized molecular sieve membranes were used for pervaporation experiments and characterization. Their pervaporation performance in a butanol / water (90 / 10wt%) system was tested (75℃). The experimental results are shown in Table 10 for SU-19 and SU-20.

[0098] Table 10

[0099]

[0100] Example 11

[0101] Macroporous alumina ceramic tubes (outer diameter 12 mm, inner diameter 8 mm, porosity 38%, average pore size 2-3 μm, length 8 cm) produced by Guangdong Jiexi Lishun Company were used as the support for the synthesis of the template-free SUZ-4 molecular sieve membrane. The support was pretreated by washing with a low-concentration acid solution and then dried for later use. The remaining synthesis ratios and preparation conditions were the same as in Example 2.

[0102] The synthesized molecular sieve membranes were used for pervaporation experiments and characterization. Their pervaporation performance in a butanol / water (90 / 10wt%) system was tested (75℃). The experimental results are shown in Table 11 for SU-21 and SU-22.

[0103] Table 11

[0104]

[0105] Comparative Example 1

[0106] The raw materials, proportions, and operating steps for the membrane synthesis sol are the same as in Example 2, except that the crystallization method is changed to rotary oven heating.

[0107] The synthesized molecular sieve membranes were used for pervaporation experiments and characterization. Their pervaporation performance in a butanol / water (90 / 10wt%) system was tested (75℃). The experimental results are shown in Table 12 for SU-23 and SU-24.

[0108] Table 12

[0109]

[0110] Comparative Example 2

[0111] The raw materials, proportions, and operating steps for membrane synthesis sol are the same as in Example 2, except that 0.5 wt% of ball milling seed induction is not added to the membrane synthesis sol.

[0112] The synthesized molecular sieve membranes were used for pervaporation experiments and characterization. Their pervaporation performance in a butanol / water (90 / 10wt%) system was tested (75℃). The experimental results are shown in Table 13 for SU-25 and SU-26.

[0113] Table 13

[0114]

[0115] Comparative Example 3

[0116] The raw materials, proportions, and operating steps of the membrane synthesis sol were the same as in Example 2, except that 0.5 wt% of non-ball milled seed crystals were added to the membrane synthesis sol for induction.

[0117] The synthesized molecular sieve membranes were used for pervaporation experiments and characterization. Their pervaporation performance in a butanol / water (90 / 10wt%) system was tested (75℃). The experimental results are shown in Table 14 for SU-27 and SU-28.

[0118] Table 14

[0119]

[0120] Comparative Examples 1 to 3 demonstrate that, under the same conditions, neither rotary oven crystallization, nor crystallization without seed induction or with non-ball milling seed induction, can yield SUZ-4 molecular sieve membranes with excellent pervaporation performance. Therefore, the method of the present invention is simple and can significantly shorten the synthesis time.

[0121] Comparative Example 4

[0122] The operation was the same as in Example 2, except that sodium hydroxide was used as the alkali source in the synthesis raw materials, and the other raw materials were the same as in Example 2.

[0123] The synthesized molecular sieve membranes were used for pervaporation experiments and characterization. Their pervaporation performance in a butanol / water (90 / 10wt%) system was tested (75℃). The experimental results are shown in Table 15 for SU-29 and SU-30.

[0124] Table 15

[0125]

[0126] Alkali metal cations also play a crucial role in the synthesis of molecular sieve membranes. Firstly, they balance the charge within the molecular sieve framework; secondly, the formation of hydrated ions facilitates the construction of the molecular sieve framework. Therefore, different alkali metal cations tend to form different molecular sieves with different framework structures. In the synthesis of SUZ-4 molecular sieve membranes, under the same synthesis conditions, potassium (K) ions are more likely to form the molecular sieve framework than sodium (Na) ions; therefore, potassium hydroxide is used as the alkali source instead of sodium hydroxide.

[0127] Comparative Example 5

[0128] The operation was the same as in Example 2, except that aluminum hydroxide was used as the aluminum source in the synthesis raw materials, and the other raw materials were the same as in Example 2.

[0129] The synthesized molecular sieve membranes were used for pervaporation experiments and characterization. Their pervaporation performance in a butanol / water (90 / 10wt%) system was tested (75℃). The experimental results are shown in Table 16 for SU-31 and SU-32.

[0130] Table 16

[0131]

[0132] Different aluminum sources have different states of Al species, resulting in different solubility states in the sol. This leads to inconsistencies with the aluminosilicate species formed after aggregation with silicon sources, thus resulting in different properties of the synthesized films.

[0133] Comparative Example 6

[0134] 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 0.025, and the rest were the same as in Example 2.

[0135] The synthesized molecular sieve membranes were used for pervaporation experiments and characterization. Their pervaporation performance in a butanol / water (90 / 10wt%) system was tested (75℃). The experimental results are shown in Table 17 for SU-33 and SU-34.

[0136] Table 17

[0137]

[0138] Comparative Example 7

[0139] 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 0.1, and the rest were the same as in Example 2.

[0140] The synthesized molecular sieve membranes were used for pervaporation experiments and characterization. Their pervaporation performance in a butanol / water (90 / 10wt%) system was tested (75℃). The experimental results are shown in Table 18 for SU-35 and SU-36.

[0141] Table 18

[0142]

[0143]

[0144] Comparative Example 8

[0145] The raw materials and operating steps for membrane synthesis sol were the same as in Example 2, except that the KOH / SiO2 ratio was adjusted to 0.3, and the rest were the same as in Example 2.

[0146] The synthesized molecular sieve membranes were used for pervaporation experiments and characterization. Their pervaporation performance in a butanol / water (90 / 10wt%) system was tested (75℃). The experimental results are shown in Table 19 for SU-37 and SU-38.

[0147] Table 19

[0148]

[0149] Comparative Example 9

[0150] The raw materials and operating steps for membrane synthesis sol are the same as in Example 2, except that the KOH / SiO2 ratio is adjusted to 1, and the rest are the same as in Example 2.

[0151] The synthesized molecular sieve membranes were used for pervaporation experiments and characterization. Their pervaporation performance in a butanol / water (90 / 10wt%) system was tested (75℃). The experimental results are shown in Table 20 for SU-39 and SU-40.

[0152] Table 20

[0153]

[0154] Comparative Examples 1 to 9 demonstrate that only within a suitable sol-particle molar ratio range and using specified raw materials can SUZ-4 molecular sieve membranes with excellent pervaporation performance be obtained. This invention solves the problems of using expensive organic template agents, excessively long crystallization time in static synthesis methods, and poor membrane reproducibility in SUZ-4 molecular sieve membranes. It provides theoretical and practical guidance for the industrial application of SUZ-4 molecular sieve membranes in dehydration systems such as butanol / water, and has broad application value in pervaporation dehydration and separation of mixed organic matter.

[0155] 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 method for rapid static synthesis of SUZ-4 molecular sieve membranes without template agent, characterized in that, Includes the following steps: S1. Preparation of template-free SUZ-4 seed crystals: Aluminum source and alkali source are mixed and dissolved in water, then silicon source is added, stirred and aged to obtain a reaction sol, then hydrothermal crystallization is performed, centrifugation is used to separate the solid phase, and the solid phase is dried and ground to obtain template-free SUZ-4 molecular sieve seed crystals. S2, Seed layer loading of support: The template-free SUZ-4 molecular sieve seed crystals prepared in step S1 are ground into crystals with a particle size of 5 micrometers to 20 micrometers, then dispersed in a solvent to prepare a seed crystal suspension, and the seed crystals are uniformly loaded on the outer surface of the porous support by hot impregnation method to obtain a seeded support. Preparation of S3 and SUZ-4 membrane reaction solutions: Using silicon source, aluminum source, alkali source and ultrapure water as raw materials, they are mixed and stirred to form a milky white suspension, aged, and the membrane reaction solution is obtained; wherein, the alkali source is potassium hydroxide, and the molar ratio of the raw materials is expressed in the form of oxides as follows: H2O / SiO2 = 5~45, KOH / SiO2 = 0.4~0.8, Al2O3 / SiO2 = 0.03~0.09; S4. Preparation of template-free SUZ-4 membrane: The template-free SUZ-4 seed crystals prepared in step S1 are added to the reaction solution obtained in step S3 at 0.5 wt% of the amount of the synthetic sol, and the seeded support obtained in step S2 is added. The mixture is placed in a reaction vessel and subjected to a static heating reaction at a temperature of 120-160℃ for 8-24 hours. After crystallization, the membrane is washed with running water until neutral and dried to obtain a template-free SUZ-4 molecular sieve membrane. In step S1, the molar ratio of the raw materials for the template-free SUZ-4 seed crystals is expressed in oxide form as: 5-40 SiO2:Al2O3:2-16 KOH:100-900 H2O. The aging process is carried out at 30-70°C for 4-24 hours. The heating method used for hydrothermal crystallization includes static oven heating or static oil bath heating. The temperature of the hydrothermal crystallization is 120-180°C, and the time is 12-26 hours.

2. The method for rapid static synthesis of SUZ-4 molecular sieve membrane without template agent according to claim 1, characterized in that, The hot impregnation process described in step S2 is as follows: the two ends of the porous support are sealed and placed in a programmable oven at a temperature of 60℃~120℃ for 10min~90min. Then, it is quickly taken out and immersed in the seed crystal suspension. The temperature and pressure difference are used to introduce the seed crystal onto the outer surface of the porous support.

3. The method for rapid static synthesis of SUZ-4 molecular sieve membrane without template agent according to claim 1, characterized in that, The porous support in step S2 includes alumina ceramic tube, stainless steel tube, zirconia ceramic tube, silica tube, or mullite tube; the average pore size of the porous support is 0.01 to 2 μm, and the porosity is 15 to 45%.

4. The method for rapid static synthesis of template-free SUZ-4 molecular sieve membranes according to claim 1, characterized in that, In step S2: the solvent includes one or more of water, ethanol, acetone, and acetic acid; The concentration of the seed crystal suspension is 0.02–1.5 wt%. The thickness of the seed layer is 0.2–7 μm.

5. The method for rapid static synthesis of SUZ-4 molecular sieve membrane without template agent according to claim 1, characterized in that, In step S3: the silicon source is silica sol, and the aluminum source includes one or more of sodium aluminate, aluminum isopropoxide, aluminum nitrate, and aluminum sulfate.

6. The method for rapid static synthesis of SUZ-4 molecular sieve membrane without template agent according to claim 1, characterized in that, In step S3: the aging process involves aging in a water bath at a temperature of 10–60°C for 4–16 hours.

7. A template-free SUZ-4 molecular sieve membrane, characterized in that, The SUZ-4 molecular sieve membrane without template agent was prepared by the static rapid synthesis method according to any one of claims 1 to 6.

8. The application of the template-free SUZ-4 molecular sieve membrane according to claim 7 in the dehydration separation of butanol / water system.

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