阅读说明：本技术 一种动态水热合成中空纤维外壁suz-4型分子筛渗透汽化膜及其溶剂脱除甲醇的方法 (Dynamic hydrothermal synthesis hollow fiber outer wall SUZ-4 type molecular sieve pervaporation membrane and method for removing methanol by using solvent thereof ) 是由 许振良 林宇飞 詹子明 张新 马晓华 程亮 于 2021-08-23 设计创作，主要内容包括：本发明属于分子筛膜的合成技术领域,具体公开了一种动态水热合成中空纤维外壁SUZ-4型分子筛渗透汽化膜及其溶剂脱除甲醇的方法,包括以下步骤：陶瓷支撑体预处理；配制晶种悬浮液；在中空纤维外壁涂覆晶种层；配制SUZ-4型分子筛合成液；将接种好的支撑体以设计好的方式放置在反应釜中并进行动态水热合成,最终经后处理得到SUZ-4型分子筛渗透汽化膜,应用于甲醇-甲基丙烯酸甲酯和甲醇-碳酸二甲脂的分离。本发明的优点在于：支撑体表面可控及晶种层质量宽容度高,渗透汽化膜分离性能优良,膜层均匀性良好,具有显著的工业应用价值。(The invention belongs to the technical field of synthesis of molecular sieve membranes, and particularly discloses a dynamic hydrothermal synthesis SUZ-4 type molecular sieve pervaporation membrane on the outer wall of a hollow fiber and a method for removing methanol by using a solvent thereof, which comprises the following steps: pretreating a ceramic support; preparing a seed crystal suspension; coating a seed crystal layer on the outer wall of the hollow fiber; preparing a synthetic solution of the SUZ-4 type molecular sieve; and placing the inoculated support body in a reaction kettle in a designed mode, carrying out dynamic hydrothermal synthesis, and finally carrying out post-treatment to obtain the SUZ-4 type molecular sieve pervaporation membrane applied to separation of methanol-methyl methacrylate and methanol-dimethyl carbonate. The invention has the advantages that: the surface of the support body is controllable, the quality tolerance of the crystal seed layer is high, the separation performance of the pervaporation membrane is excellent, the uniformity of the membrane layer is good, and the industrial application value is obvious.)

1. A method for dynamically synthesizing a SUZ-4 type molecular sieve pervaporation membrane on the outer wall of a hollow fiber by hydrothermal method is characterized by comprising the following steps:

(1) taking porous ceramic hollow fibers as a support body, and pretreating the porous ceramic hollow fibers;

(2) ultrasonically dispersing the ground SUZ-4 type molecular sieve particles into deionized water, adding 0.1-0.3 wt.% of hydroxypropyl cellulose, adjusting the pH to 3-5 by using 0.5-2.0mol/L nitric acid, and preparing a seed crystal suspension with the solid content of 0.5-2.0 wt.%;

(3) coating a seed layer: sealing two ends of the support body pretreated in the step (1) by using a raw material tape, placing the support body into the seed crystal suspension prepared in the step (2), standing for 20-60 s, taking out the support body within 5-30s, and then placing the support body into an oven with the temperature of 60-80 ℃ for drying for 30-60 min; repeating the step for several times, and after the crystal coating is finished, putting the support body into an oven at 80-100 ℃ for drying for 1-3 h;

(4) preparing a synthetic solution: according to the proportion of 7.9KOH:1Al₂O₃:2.6TEAOH:21.2SiO₂:498.6H₂O is prepared from Si source, Al source,Dissolving a potassium source and an organic template agent in deionized water to prepare a synthetic solution;

(5) dynamic hydrothermal synthesis of SUZ-4 separation layer: fixing two ends of the support body after crystal coating by using a polytetrafluoroethylene plate with a hole groove, and vertically placing the support body in the lining of the hydrothermal synthesis kettle; pouring the synthetic liquid and ensuring that the support body can be completely immersed when the synthesis kettle is placed on the side; placing the synthesis kettle on a turntable of a homogeneous reactor, and carrying out dynamic hydrothermal synthesis at the rotation speed of 20-50 rmp and the temperature of 120-160 ℃; and after the dynamic hydrothermal synthesis is carried out for 12-48h, taking out the membrane tube, cleaning, standing at room temperature overnight and drying.

(6) Removing the organic template agent by heat treatment: and (3) placing the membrane obtained in the step (5) in a muffle furnace, raising the temperature of the furnace to 500-600 ℃ at a heating and cooling rate of 0.1-0.5 ℃/min, and preserving the temperature for 4-8h to remove the template agent, thus obtaining the SUZ-4 type molecular sieve pervaporation membrane.

2. The method for dynamically and hydrothermally synthesizing the SUZ-4 type molecular sieve pervaporation membrane on the outer wall of the hollow fiber according to claim 1, wherein the pretreatment is to soak the membrane in 0.5-2.0mol/L sodium hydroxide solution for 24 hours, take out the membrane, ultrasonically clean the membrane until the pH value is neutral, and dry the membrane in an oven at 70-90 ℃.

3. The method for dynamically hydrothermally synthesizing the SUZ-4 type molecular sieve pervaporation membrane on the outer wall of the hollow fiber according to claim 1, wherein in the step (5), after the membrane tube is taken out, the membrane tube is ultrasonically cleaned for 20-50 min by deionized water; the mixture was washed three times, and then left to stand at room temperature overnight for drying.

4. The dynamic hydrothermal synthesis method for the SUZ-4 type molecular sieve pervaporation membrane for the hollow fiber outer wall according to claim 1, wherein the homogeneous reactor in the step (5) has a rotating turntable which can adjust the rotating speed and fix the reaction kettle.

5. The method for dynamically hydrothermally synthesizing the SUZ-4 type molecular sieve pervaporation membrane for the outer wall of the hollow fiber according to claim 1, wherein the thickness of the membrane layer is 2-5 μm.

6. The SUZ-4 type molecular sieve pervaporation membrane for the outer wall of the dynamic hydrothermal synthesis hollow fiber prepared by the method for dynamically synthesizing the SUZ-4 type molecular sieve pervaporation membrane for the outer wall of the dynamic hydrothermal synthesis hollow fiber according to any one of claims 1 to 5.

7. The SUZ-4 type molecular sieve pervaporation membrane with the dynamic hydrothermal synthesis hollow fiber outer wall as claimed in claim 6, wherein the SUZ-4 type molecular sieve membrane is used for a pervaporation separation experiment of 10 wt.% methanol-methyl methacrylate, and when the temperature is 50 ℃, the concentration of the coated seed crystal is 1.0 wt.%, and the crystallization time is 24 hours, the selective separation factor of the membrane on water in the system exceeds 10000, and the flux can reach 3.83kg/m²H; when the SUZ-4 type molecular sieve membrane is used for a pervaporation separation experiment of a 10 wt.% methanol-dimethyl carbonate system, the selective separation factor of the membrane on water in the system can reach 3037, and the flux can reach 1.56kg/m when the temperature is 50 ℃, the concentration of the coated seed crystal is 1.0 wt.%, and the crystallization time is 24 hours²·h。

8. The application of the SUZ-4 type molecular sieve pervaporation membrane for the dynamic hydrothermal synthesis of the hollow fiber outer wall according to claim 6 in purification of a pervaporation organic solvent.

9. The method for removing methanol from the dynamic hydrothermal synthesis hollow fiber outer wall SUZ-4 type molecular sieve pervaporation membrane solvent according to claim 6, which comprises the following steps: under the condition of heating in a water bath, a mixed solution of methanol and methyl methacrylate or methanol and dimethyl carbonate is contacted with the SUZ-4 type molecular sieve membrane; the dissolution and diffusion process is carried out, and the molecules penetrating through the membrane are continuously removed under the push of the pressure difference generated by the vacuum pump; at the cold trap, the membrane-permeated molecules on the permeate side condense and are collected in a glass test tube, separating out methanol.

Technical Field

The invention belongs to the technical field of synthesis of molecular sieve membranes, and particularly relates to a dynamic hydrothermal synthesis hollow fiber outer wall SUZ-4 type molecular sieve pervaporation membrane and a method for removing methanol by using a solvent thereof.

Background

The inorganic molecular sieve material has good adsorption, catalysis, shape selectivity and ion exchange performance, so that the inorganic molecular sieve material can be widely applied to a separation membrane preparation process as a membrane material. Compared with separation membranes made of other inorganic materials, the molecular sieve membrane has a neat and uniform pore channel structure which is convenient to regulate, and although the pore channel size is different due to the type of the molecular sieve, the molecular sieve membrane is similar to the molecular size of a plurality of important industrial raw materials, and has the characteristics of good chemical stability, thermal stability, pollution resistance and easiness in modification, so that the molecular sieve membrane has wide application prospects in the fields of gas separation, pervaporation separation, membrane reactors, sensors and the like. Although there are many types of zeolite molecular sieves known, the molecular sieve membranes that have been prepared are relatively limited, and it is therefore of great interest to develop more types of zeolite membranes.

SUZ-4 zeolite molecular sieves having a three-dimensional pore structure consisting of five-, six-, eight-and ten-membered rings were first discovered and prepared in 1992. The largest ten-membered ring pore size of the SUZ-4 molecular sieve is 0.52nm x 0.46nm, which is close to the size of many molecules and thus has a potential in separation applications. Currently, SUZ-4 molecular sieves have been studied for catalytic performance. Teketel (J.Catal.327(2015)22-32) performed a related study on the catalytic performance of SUZ-4 molecular sieve in methanol to hydrocarbons. Dyballa (Microporous MeOporous Mater.265(2018)112-122) optimized SUZ-4 zeolite and studied its application in the conversion of methanol to olefins and methane to methanol. Gaoshan et al (Microporous Mesoporous mater.159(2012)105-110, Microporous Mesoporous mater.174(2013)108-116) propose a crystal growth mechanism for synthesizing nano-fiber-shaped SUZ-4 zeolite, and explore a template-free green synthesis method for SUZ-4 zeolite. However, few studies on the preparation of SUZ-4 zeolite membranes for the separation of organic compounds have been reported in the literature.

Among the membrane technologies, the pervaporation technology has the advantages of simplicity, flexibility, low energy consumption, small occupied area and the like, and is particularly suitable for separating azeotropic mixtures, heat-sensitive compounds and organic mixtures, which provides a new idea for purifying some organic matters. It is worth considering that pervaporation technology is adopted to remove methanol from methyl methacrylate, dimethyl carbonate and other common organic matters. The process is less energy intensive than conventional distillation processes and does not present thermodynamic equilibrium limitations. The prepared high-performance molecular sieve membrane material is applied to the pervaporation technology for separating organic mixtures, and has a research direction with wide application prospect.

Disclosure of Invention

In order to solve the technical problems that the consumption of synthetic solution in the conventional static hydrothermal synthesis is large, the synthesized molecular sieve membrane layer is thick and has easy appearance of mixed crystals, and the performance of the molecular sieve membrane tube is improved, the invention provides a dynamic hydrothermal synthesis hollow fiber outer wall SUZ-4 type molecular sieve pervaporation membrane and a method for removing methanol by using a solvent thereof.

The technical scheme of the invention is as follows:

the invention provides a method for dynamically synthesizing SUZ-4 type molecular sieve pervaporation membrane on outer wall of hollow fiber by hydrothermal synthesis, which adopts dynamic hydrothermal synthesis system to provide uniform synthesis conditions for each part of outer wall of hollow fiber, dynamically synthesizes SUZ-4 type molecular sieve membrane, and comprises the following steps:

(1) taking porous ceramic hollow fiber as a support body, firstly, pretreating the porous ceramic hollow fiber: soaking the mixture in 0.5-2.0mol/L sodium hydroxide solution for 24h, taking out the mixture, ultrasonically cleaning the mixture until the pH value is neutral, and drying the mixture in an oven at 70-90 ℃;

(2) ultrasonically dispersing the ground SUZ-4 type molecular sieve particles into deionized water, adding 0.1-0.3 wt.% of hydroxypropyl cellulose, and adjusting the pH to 3-5 by using 0.5-2.0mol/L nitric acid to prepare a seed crystal suspension with the solid content of 0.5-2.0 wt.%;

(3) coating a seed layer: sealing two ends of the support body dried in the step (1) by using a raw material tape, slowly putting the support body into the seed crystal suspension prepared in the step (2), standing for 20-60 s, taking out the support body within 5-30s, and then putting the support body into an oven with the temperature of 60-80 ℃ for drying for 30-60 min; repeating the step for three times, and after the crystal coating is finished, putting the support body into an oven with the temperature of 80-100 ℃ for drying for 1-3 h;

(4) preparing a synthetic solution: according to the proportion of 7.9KOH:1Al₂O₃:2.6TEAOH:21.2SiO₂:498.6H₂Dissolving a silicon source, an aluminum source, a potassium source and an organic template agent in deionized water to prepare a synthetic liquid;

(5) dynamic hydrothermal synthesis of SUZ-4 separation layer: fixing two ends of the support body after crystal coating by using a polytetrafluoroethylene plate with a hole groove, and vertically placing the support body in the lining of the hydrothermal synthesis kettle. The synthesis solution was poured slowly and it was ensured that the support could be completely submerged when the synthesis kettle was placed on its side. And placing the synthesis kettle on a turntable of the homogeneous reactor, and performing dynamic hydrothermal synthesis at the rotation speed of 20-50 rmp and the temperature of 120-160 ℃. And after the dynamic hydrothermal synthesis is carried out for 12-48h, taking out the membrane tube, and ultrasonically cleaning the membrane tube for 20-50 min by using deionized water. Then washed three times, placed at room temperature, and dried overnight.

(6) Removing the organic template agent by heat treatment: and (3) placing the membrane obtained in the step (5) in a muffle furnace, raising the temperature of the furnace to 500-600 ℃ at a heating and cooling rate of 0.1-0.3 ℃/min, preserving the temperature for 4-8h, removing the template agent, and then obtaining the SUZ-4 type molecular sieve pervaporation membrane.

Further, the specific surface area of the SUZ-4 type molecular sieve particles after grinding in the step (2) is 320-360m²/g。

The homogeneous reactor in the step (5) is provided with a rotary turntable which can adjust the rotating speed and fix the reaction kettle.

The invention also provides the SUZ-4 type molecular sieve pervaporation membrane for the outer wall of the dynamic hydrothermal synthesis hollow fiber, which is prepared by the method for dynamically synthesizing the SUZ-4 type molecular sieve pervaporation membrane for the outer wall of the dynamic hydrothermal synthesis hollow fiber.

The invention also provides an application of the SUZ-4 type molecular sieve pervaporation membrane on the outer wall of the dynamic hydrothermal synthesis hollow fiber in purification of a pervaporation organic solvent.

The invention further provides an application method of the dynamic hydrothermal synthesis hollow fiber outer wall SUZ-4 type molecular sieve pervaporation membrane solvent for methanol removal, wherein a pervaporation device shown in figure 6 is used for contacting a mixed solution of methanol and methyl methacrylate or methanol and dimethyl carbonate with a molecular sieve membrane under the condition of heating in a water bath kettle. At this time, the dissolution and diffusion process occurs, and the molecules permeating the membrane are continuously removed under the push of the pressure difference generated by the vacuum pump, so that the permeation process is continuously performed. At the cold trap, the membrane-permeated molecules on the permeate side condense and are collected in a glass test tube, resulting in methanol being separated from the mixture. The SUZ-4 type molecular sieve membrane is used for pervaporation separation experiments of 10 wt.% methanol-methyl methacrylate and 10 wt.% methanol-dimethyl carbonate system, when the temperature is 50 ℃, the concentration of the coated seed crystal is 1.0 wt.%, and the crystallization time is 24 hours, the selective separation factor of the membrane to water in the system exceeds 10000, and the flux can reach 3.83kg/m²H; when the SUZ-4 type molecular sieve membrane is used for a pervaporation separation experiment of a 10 wt.% methanol-dimethyl carbonate system, the selective separation factor of the membrane on water in the system can reach 3037, and the flux can reach 1.56kg/m when the temperature is 50 ℃, the concentration of the coated seed crystal is 1.0 wt.%, and the crystallization time is 24 hours²·h。

The SUZ-4 type molecular sieve pervaporation membrane for the outer wall of the dynamic hydrothermal synthesis hollow fiber has wide requirements on a seed crystal layer, the surface of the molecular sieve membrane synthesized by the method is compact and continuous through SEM observation, no mixed crystal is generated, and the thickness is 2-5 mu m.

According to the method, the synthesized SUZ-4 type molecular sieve membrane is used for a pervaporation separation experiment of a 10 wt.% methanol-methyl methacrylate system, when the temperature is 50 ℃, the concentration of the coated seed crystal is 1.0 wt.%, and the crystallization time is 24 hours, the selective separation factor of the membrane to water in the system exceeds 10000, and the flux can reach 3.83kg/m²H; when the SUZ-4 type molecular sieve membrane is used for a pervaporation separation experiment of a 10 wt.% methanol-dimethyl carbonate system, the membrane selects water in the system when the temperature is 50 ℃, the concentration of the coated seed crystal is 1.0 wt.%, and the crystallization time is 24 hoursThe separation factor can reach 3037, and the flux can reach 1.56kg/m²·h。

Further, the present invention can be applied to methanol removal of any concentration of methanol-methyl methacrylate, for example, 5-20 wt.% methanol-methyl methacrylate was tested in experiments to meet expected performance.

One of the innovation points of the invention is that the SUZ-4 zeolite molecular sieve is prepared into a zeolite membrane and is applied to the pervaporation process to purify the organic solvent. The invention overcomes the difficulties that the zeolite molecular sieve material has poor film-forming property and is difficult to prepare into a zeolite film, and simultaneously overcomes the difficulty that the pervaporation technology is applied to an organic mixture system.

The synthetic liquid used in the invention is less, the synthetic liquid is required to be ensured to submerge the support body during the synthesis of the zeolite molecular sieve membrane, the synthetic liquid with the volume of about half of the volume of the lining is required at least by a dynamic method during the synthesis of the molecular sieve membrane with the same length as the lining, and the whole lining is required to be filled in a static process. The consumption of the synthetic liquid is reduced, namely the consumption of raw materials is reduced, thereby reducing the cost. The overall synthetic process is relatively simple, and the cost is reduced, which is a factor beneficial to industrial production.

The SUZ-4 type molecular sieve membrane for synthesizing the outer wall of the hollow fiber has the advantages that: the method has the advantages of simple equipment, high film forming repeatability, excellent performance, better film performance compared with a static synthesis method, less synthesis liquid used in the synthesis of the film with the same length, further reduction of the synthesis cost of the molecular sieve film and contribution to industrial production.

Drawings

FIG. 1 is a scanning electron microscope (surface view) of a SUZ-4 type molecular sieve membrane synthesized on the outer surface of a ceramic hollow fiber support in example 1;

FIG. 2 is a scanning electron micrograph (cross-sectional view) of a SUZ-4 type molecular sieve membrane synthesized on the outer surface of the ceramic hollow fiber support in example 1;

FIG. 3 is a scanning electron micrograph (surface view) of a SUZ-4 type molecular sieve membrane synthesized on the outer surface of the ceramic hollow fiber support in example 2;

FIG. 4 is a schematic representation of a membrane tube in a reactor liner;

FIG. 5 is a schematic view of the interior of a reaction vessel during hydrothermal synthesis;

FIG. 6 is a schematic view of an apparatus for conducting the pervaporation test in examples 1 to 3;

wherein: 1-stirrer and water bath; 2-flask; 3, 4, 5-valve; 6-vacuum differential pressure gauge; a 7, 8-tee type assembly; 9-a pump; 10, 11-cold trap.

Detailed Description

The invention provides a SUZ-4 type molecular sieve pervaporation membrane for dynamic hydrothermal synthesis of hollow fiber outer wall and a specific implementation mode of a method for removing methanol by using a solvent thereof.

Example 1:

(1) with a length of 4cm of alpha-Al₂O₃Soaking hollow fiber as support in 1.0mol/L sodium hydroxide solution for 24 hr, ultrasonically cleaning with deionized water to neutrality, and drying completely in 70 deg.C oven;

(2) ultrasonically dispersing the ground SUZ-4 type molecular sieve particles into deionized water, adding 0.2 wt.% of hydroxypropyl cellulose into the deionized water, and adjusting the pH to 3 by using 1.0mol/L nitric acid to prepare a seed crystal suspension with the solid content of 1.0 wt.%;

(3) coating a seed layer: sealing two ends of the support body dried in the step (1) by using a raw material tape, slowly placing the support body into the seed crystal suspension prepared in the step (2), standing for 30s, taking out the support body within 10s, and then placing the support body into a 60 ℃ oven to be dried for 30 min; repeating the step for three times, and after the crystal coating is finished, putting the support body into an oven at 80 ℃ for drying for 2 hours;

(4) preparing a synthetic solution: according to the proportion of 7.9KOH:1Al₂O₃:2.6TEAOH:21.2SiO₂:498.6H₂Dissolving a silicon source, an aluminum source, a potassium source and an organic template agent in deionized water to prepare a synthetic liquid;

(5) dynamic hydrothermal synthesis of SUZ-4 separation layer: fixing two ends of the support body after crystal coating by using a polytetrafluoroethylene plate with a hole groove, and vertically placing the support body in the lining of the hydrothermal synthesis kettle. The synthesis solution was poured slowly and it was ensured that the support could be completely submerged when the synthesis kettle was placed on its side. The synthesis kettle is placed on a rotating disc of a homogeneous reactor, and dynamic hydrothermal synthesis is carried out under the conditions that the rotating speed is 20rmp and the temperature is 150 ℃. And after 24 hours of dynamic hydrothermal synthesis, taking out the membrane tube, and ultrasonically cleaning the membrane tube for 30 minutes by using deionized water. The mixture was washed three times, and then left to stand at room temperature overnight for drying.

(6) Removing the organic template agent by heat treatment: and (3) placing the membrane obtained in the step (5) in a muffle furnace, heating the furnace to 500 ℃ at the heating and cooling rate of 0.2 ℃/min, preserving the temperature for 4 hours, removing the template agent, and then obtaining the SUZ-4 type molecular sieve pervaporation membrane.

(7) Pervaporation testing of molecular sieve membranes: the prepared outer wall molecular sieve membrane was subjected to a separation performance test in a pervaporation system of 10 wt.% methanol-methyl methacrylate (apparatus shown in fig. 5).

Example 2:

step (1) same as example 1;

(2) ultrasonically dispersing the ground SUZ-4 type molecular sieve particles into deionized water, adding 0.2 wt.% of hydroxypropyl cellulose into the deionized water, and adjusting the pH to 3 by using 1.0mol/L nitric acid to prepare a seed crystal suspension with the solid content of 1.5 wt.%;

steps (3) to (7) were the same as in example 1.

Example 3:

the steps (1) to (4) are the same as in example 1;

(5) dynamic hydrothermal synthesis of SUZ-4 separation layer: fixing two ends of the support body after crystal coating by using a polytetrafluoroethylene plate with a hole groove, and vertically placing the support body in the lining of the hydrothermal synthesis kettle. The synthesis solution was poured slowly and it was ensured that the support could be completely submerged when the synthesis kettle was placed on its side. The synthesis kettle is placed on a rotating disc of a homogeneous reactor, and dynamic hydrothermal synthesis is carried out under the conditions that the rotating speed is 20rmp and the temperature is 150 ℃. And after the dynamic hydrothermal synthesis is carried out for 36 hours, taking out the membrane tube, and ultrasonically cleaning the membrane tube for 30min by using deionized water. The mixture was washed three times, and then left to stand at room temperature overnight for drying.

Steps (6) to (7) were the same as in example 1.

Example 4:

the steps (1) to (4) are the same as in example 1;

(5) dynamic hydrothermal synthesis of SUZ-4 separation layer: fixing two ends of the support body after crystal coating by using a polytetrafluoroethylene plate with a hole groove, and vertically placing the support body in the lining of the hydrothermal synthesis kettle. The synthesis solution was poured slowly and it was ensured that the support could be completely submerged when the synthesis kettle was placed on its side. The synthesis kettle is placed on a rotating disc of a homogeneous reactor, and dynamic hydrothermal synthesis is carried out under the conditions that the rotating speed is 20rmp and the temperature is 150 ℃. And after the dynamic hydrothermal synthesis is carried out for 48 hours, taking out the membrane tube, and ultrasonically cleaning the membrane tube for 30min by using deionized water. The mixture was washed three times, and then left to stand at room temperature overnight for drying.

Steps (6) to (7) were the same as in example 1.

Example 5:

steps (1) to (6) were the same as in example 1;

(7) pervaporation testing of molecular sieve membranes: the prepared outer wall molecular sieve membrane was subjected to a separation performance test in a pervaporation system of 10 wt.% methanol-dimethyl carbonate (apparatus shown in fig. 5).

Example 6:

the steps (1) to (4) are the same as in example 1;

(5) dynamic hydrothermal synthesis of SUZ-4 separation layer: fixing two ends of the support body after crystal coating by using a polytetrafluoroethylene plate with a hole groove, and vertically placing the support body in the lining of the hydrothermal synthesis kettle. The synthesis solution was poured slowly and it was ensured that the support could be completely submerged when the synthesis kettle was placed on its side. The synthesis kettle is stood in a homogeneous reactor, and the static hydrothermal synthesis is carried out under the condition that the temperature is 150 ℃. And after 24 hours of static hydrothermal synthesis, taking out the membrane tube, and ultrasonically cleaning the membrane tube for 30 minutes by using deionized water. The mixture was washed three times, and then left to stand at room temperature overnight for drying.

Steps (6) to (7) were the same as in example 1.

Example 7:

steps (1) to (6) were the same as in example 2;

(7) pervaporation testing of molecular sieve membranes: the prepared outer wall molecular sieve membrane was subjected to a separation performance test in a pervaporation system of 5 wt.% methanol-methyl methacrylate (apparatus shown in fig. 5).

Example 8:

steps (1) to (6) were the same as in example 2;

(7) pervaporation testing of molecular sieve membranes: the prepared outer wall molecular sieve membrane was subjected to a separation performance test in a pervaporation system of 15 wt.% methanol-methyl methacrylate (apparatus shown in fig. 5).

Table 1 shows the results of pervaporation experiments on SUZ-4 molecular sieve membranes synthesized in examples 1-5, at a temperature of 50 ℃.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, several modifications and decorations can be made without departing from the concept of the present invention, and these modifications and decorations should also be regarded as being within the protection scope of the present invention.