A method for preparing an ionic liquid functionalized silicalite-1@SiO2 mixed matrix membrane

Abstract

The application relates to the technical field of gas separation materials, in particular to a preparation method of an ionic liquid functionalized Silicalite-1@SiO2 mixed matrix membrane. The ionic liquid loaded Silicalite-1@SiO2 filler with a large specific surface area and CO2 adsorption performance is prepared to solve the problems of low CO2 / N2 permeability and selectivity and poor interface compatibility of the membrane material. The high specific surface area of the Silicalite-1@SiO2 nanoparticles provides rich active sites, enhances the gas adsorption capacity and improves the separation efficiency. The ionic liquid 1-butyl-3-methyl imidazole tetrafluoroborate enhances the dissolution and adsorption of CO2 through physical adsorption, the strong van der Waals force between the anion and the CO2 molecule promotes the selective capture of CO2. The functionalization of the Silicalite-1@SiO2 surface improves the selectivity of CO2 / N2, and can also adjust the interaction force with CO2, thereby improving the separation effect.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of gas separation materials, in particular to a preparation method of an ion liquid functionalized Silicalite-1@SiO2 mixed matrix membrane. BACKGROUND

[0002] CO2 is one of the most pressing environmental problems facing mankind today. CO2 is one of the main components of greenhouse gases, and its substantial increase in emissions has led to an increase in the temperature of the earth, which in turn has triggered a series of environmental problems such as extreme climate and rising sea levels. According to the report of the Intergovernmental Panel on Climate Change (IPCC), significant CO2 emission reduction must be achieved in the next few decades to avoid serious climate consequences. Therefore, CO2 gas separation technology has become one of the key means to achieve this goal.

[0003] Current CO2 separation technologies, including chemical adsorption, physical adsorption, etc., generally have the problems of high energy consumption and high cost. Especially in a low-concentration CO2 environment (such as air), more energy is needed to separate and capture CO2, so it is crucial to find an efficient and economical separation method. Membrane separation technology is gradually replacing some traditional separation technologies and becoming an indispensable separation means in modern industry due to its high efficiency, environmental protection, easy operation and low cost.

[0004] With the continuous development of CO2 separation membranes, the membrane materials are also carefully studied and found that both polymers and inorganic materials have their own advantages and disadvantages. Polymers are easy to form films and have stable chemical structure, but have poor aging and plasticizing performance, which affects the separation performance of the membrane. Inorganic materials are not easy to form films and process, are brittle, and have high cost, which seriously restricts the development. In the field of gas separation membrane research, the most typical trade-off effect is the balance between permeability and selectivity. With the increase of permeability, the selectivity tends to decrease; with the increase of selectivity, the permeability tends to decrease. The trade-off effect limits the separation performance and application of the membrane. However, MMMs are a kind of composite membrane composed of polymer matrix and inorganic filler, which aims to combine the advantages of polymer membranes and inorganic membranes, make the best of both worlds, and achieve better separation performance. Mixed matrix membranes combine the advantages of polymers and inorganic materials, and show good gas selectivity, high temperature resistance, chemical corrosion resistance and cost-effectiveness, and are particularly suitable for industrial applications such as gas separation, liquid purification and wastewater treatment. By optimizing the type, size and distribution of inorganic fillers, and the compatibility of polymer matrix, the separation performance of mixed matrix membranes can be further improved, which becomes an important direction for the development of future separation technology. SUMMARY

[0005] The present application aims to provide a method for preparing an ionic liquid functionalized Silicalite-1@SiO2 mixed matrix membrane, which comprises mixing the prepared ionic liquid functionalized Silicalite-1@SiO2 nanoparticle filler with a Pebax-1657 solution to form a uniform casting solution, and then using a solvent evaporation method to prepare the mixed matrix membrane. The ionic liquid functionalized Silicalite-1@SiO2 nanoparticle filler is a high-performance composite material that combines the MFI-type structure of molecular sieve Silicalite-1, the stability of silica, and the functionality of ionic liquid. This nanoparticle filler has unique chemical properties, and due to its large specific surface area and high surface energy, the material has extremely high chemical activity. Specifically, Silicalite-1@SiO2 as a carrier can improve the loading capacity of ionic liquid, which is particularly important when preparing a mixed matrix membrane. The addition of ionic liquid not only greatly improves the compatibility of Silicalite-1@SiO2 and the polymer matrix, but also improves the selectivity of CO2 through the functional groups in the ionic liquid, which is crucial for improving the performance of the mixed matrix membrane. In addition, the dispersion ability of ionic liquid functionalized Silicalite-1@SiO2 nanoparticles in non-polar solvents is significantly improved, which not only facilitates the preparation of the membrane, but also avoids the agglomeration of the filler, thereby improving the uniform dispersion of the filler in the mixed matrix membrane. This uniform dispersion is crucial for ensuring the consistency of the membrane performance and optimizing its separation efficiency. The introduction of ionic liquid not only enhances the hydrophilicity and thermal stability of the nanoparticles, but also improves their adsorption selectivity for specific gas molecules. Therefore, the addition of Silicalite-1@SiO2 and the functionalization of ionic liquid together provide a series of advantages for the composite material, making it show great potential in high-performance applications. The physicochemical properties of ionic liquid functionalized Silicalite-1@SiO2 nanoparticles can be adjusted by controlling the synthesis conditions to meet different application requirements.

[0006] The patent selects Pebax-1657 as the membrane matrix, which is copolymerized by 40wt% PA and 60wt% PE. This model is selected because it has certain mechanical strength and good CO2 adsorption performance. The Silicalite-1@SiO2 particles as fillers provide rich active sites for CO2 gas molecules with high specific surface area, enhance the interaction with gas molecules, and thus improve the gas adsorption capacity. At the same time, the molecular sieve characteristics of Silicalite-1 enable it to selectively adsorb or separate according to the size and shape of the molecules, and the surface modified SiO2 can enhance the combination with the polymer matrix through hydrogen bonds or van der Waals forces. This not only increases the active sites, but also improves the reaction and separation efficiency. The fillers and the matrix form a uniform phase interface, and the fillers can effectively participate in the gas separation process. The dissolution and adsorption of CO2 in the ionic liquid is mainly realized by physical adsorption, and the physical adsorption process depends on the dissolution capacity of the ionic liquid and the polarity characteristics of the CO2 molecules. Generally, the polarity of the anion [BF4]- in 1-butyl-3-methyl imidazole tetrafluoroborate [Bmim][BF4] is strong, and the van der Waals interaction between CO2 molecules is strong, so that CO2 can be more stably dissolved in the ionic liquid, thereby realizing selective capture; the functionalization of ionic liquid functionalized Silicalite-1@SiO2 surface can improve the selectivity of specific gas and adjust the interaction force with target gas molecules; the ionic liquid functionalized Silicalite-1@SiO2 mixed matrix membrane prepared by the filler can overcome the balance effect to some extent and improve the separation performance of the membrane; the ionic liquid functionalized Silicalite-1@SiO2 with CO2 adsorption performance is introduced into Pebax-1657 by blending, and Pebax-1657 has good interfacial compatibility with ionic liquid functionalized Silicalite-1@SiO2, thereby solving the problem of low CO2 / N2 permeability and selectivity of the membrane material. The CO2 permeability (PCO2) thereof can reach 83.43-115.64 Barrer, and the CO2 / N2 selectivity can reach 57.24-78.28.

[0007] To solve the above technical problems, the application provides a preparation method of an ionic liquid functionalized Silicalite-1@SiO2 mixed matrix membrane, which comprises the following steps:

[0008] A preparation method of an ionic liquid functionalized Silicalite-1@SiO2 mixed matrix membrane, comprising the following steps:

[0009] Step 1, Pebax-1657 and ethanol aqueous solution were placed in a flask, and the uniform concentration of Pebax solution was obtained by oil bath at 60-80℃ for 4 hours, wherein the mass ratio of Pebax-1657 to ethanol aqueous solution was 1:7-32;

[0010] Step 2, the mixture was prepared by uniformly mixing white carbon black and tetrapropyl ammonium hydroxide, the mixture was added to an open glass container, and the mixture was transferred to the inner liner of the hydrothermal reaction kettle, 2-20 mL of deionized water was added outside the glass bottle mouth of the inner liner, and the crystalline product was obtained after the encapsulated hydrothermal reaction kettle was crystallized at 130-150℃ for 4-10 hours, and the product was centrifuged, washed, dried, and calcined to obtain Silicalite-1 nanocrystals, wherein the mass ratio of white carbon black to tetrapropyl ammonium hydroxide was 1:0.8-5;

[0011] Step 3, Silicalite-1 and ethanol were added to a round-bottom flask in a mass ratio of 1:10-100, and then a mixed solution of tetraethyl orthosilicate and ethanol was added after ultrasonic treatment for 30-60 minutes, and the mixture was heated at 60-80℃ for 1-2 hours at a speed of 400-600 r / min, and then 1-butyl-3-methyl imidazole tetrafluoroborate was added and heated for 5-10 hours, and then concentrated hydrochloric acid was added dropwise until a gel state appeared, and then the stirring was stopped, and the product was aged at 20-30℃ for 12-20 hours, and then the product was placed in a vacuum drying oven and dried at 150℃ for 6-12 hours to obtain the target product ionic liquid functionalized Silicalite-1@SiO2 white powder, and the above raw materials were in a mass ratio of Silicalite-1: tetraethyl orthosilicate: 1-butyl-3-methyl imidazole tetrafluoroborate: concentrated hydrochloric acid = 1:2-5:3-6:7-11;

[0012] Step 4, the ionic liquid functionalized Silicalite-1@SiO 2加入 Step 4, the ionic liquid functionalized Silicalite-1@SiO

[0013] Step 5, Pebax-1657 solution was added to a reagent bottle, and ionic liquid functionalized Silicalite-1@SiO2 filler casting solution was added dropwise, and the mixture was stirred for 2-4 hours and ultrasonically treated for 10-20 minutes, and then the casting solution was left to stand and degassed after the filler and the polymer solution were uniformly mixed; the prepared mixed matrix membrane solution was poured into a polytetrafluoroethylene flat plate, and then the flat plate was placed in a constant temperature oven at 60-80℃ for drying for 18-24 hours, and then the flat plate was placed in a vacuum oven for vacuumizing to continue to remove the solvent for 10-12 hours to obtain the ionic liquid functionalized Silicalite-1@SiO2 mixed matrix membrane.

[0014] Further, the mass ratio of tetraethyl orthosilicate and ethanol in the mixed solution of step 3 is 1:1-5.

[0015] Further, the mass ratio of ethanol and water in the aqueous ethanol solution of step 3 is 6-9:1-4.

[0016] Further, the mass ratio of the Pebax-1657 solution and the ionic liquid functionalized Silicalite-1@SiO2 filler casting solution in step 5 is 4-20:1.

[0017] Further, the preparation method of the ionic liquid functionalized Silicalite-1@SiO2 mixed matrix membrane according to any one of claims 1-4, the mixed matrix membrane prepared by the method is used for CO2 / N2 gas separation.

[0018] The preparation method of the ionic liquid functionalized Silicalite-1@SiO2 mixed matrix membrane provided by the application uses Pebax-1657 as a matrix material, and ionic liquid functionalized Silicalite-1@SiO2 nanoparticle fillers to prepare a mixed matrix membrane by blending, thereby effectively improving the solubility selectivity of the membrane material to CO2 gas.

[0019] The ionic liquid functionalized Silicalite-1@SiO2 composite material is a core-shell structure material, in which SiO2 is formed on the outer layer of Silicalite-1 nanocrystals. This structure is obtained by direct synthesis in a eutectic mixture, in which amorphous SiO2 is transformed into MFI-type structure and is coated with amorphous SiO2. In this structure, Silicalite-1 crystals grow in situ, and their physicochemical properties are strongly influenced by alkalinity, template and crystallization time. By controlling these factors, the physicochemical properties of SiO2@Silicalite-1 can be adjusted. The formation process of this composite material follows the mechanism of in-situ epitaxial growth and phase transformation. The high specific surface area of SiO2 nanoparticles provides abundant active sites for gas molecules, enhancing the interaction with gas molecules and thus improving gas adsorption capacity, which is crucial for improving gas separation efficiency. At the same time, the molecular sieve characteristics of Silicalite-1 enable selective adsorption or separation according to the size and shape of the molecules, which not only increases the active sites but also improves the reaction and separation efficiency. In addition, CO2 dissolution and adsorption in ionic liquids is mainly achieved through physical adsorption, which depends on the solubility of ionic liquids and the polar characteristics of CO2 molecules. Due to the strong polarity of anions in ionic liquids, the van der Waals interaction between them and CO2 molecules is more significant, which enables CO2 to be more stably dissolved in ionic liquids, achieving selective capture of CO2. Therefore, the ionic liquid functionalized Silicalite-1@SiO2 composite material not only performs well in gas adsorption and separation, but also has important application potential in improving reaction efficiency and selectivity. The CO2 permeability (PCO2) of the ionic liquid functionalized Silicalite-1@SiO2 composite material for the preparation of mixed matrix membranes as filler can reach 83.43-115.64 Barrer, and the selectivity of CO2 / N2 can reach 57.24-78.28. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 Silicalite-1 synthesis process sample figure (left figure for 1 hour, right figure for 6 hours);

[0021] Figure 2 X-ray diffraction pattern of the mixed matrix membrane of Comparative Example 1 and Examples 1-4 Silicalite-1;

[0022] Figure 3 X-ray diffraction pattern of Silicalite-1@Pebax-1657 mixed matrix membrane of Comparative Example 2, Silicalite-1 nanocrystal synthesis of Comparative Examples 3-4;

[0023] Figure 4The performance chart of the mixed matrix membrane of Examples 1-4 and Comparative Examples 1-2 is shown. DETAILED DESCRIPTION

[0024] In order to make the objects, technical solutions and advantages of the present application clearer, the technical solutions of the present application will be described clearly and completely below in combination with the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application and not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative labor fall within the protection scope of the present application.

[0025] The preparation method of the ion liquid functionalized Silicalite-1@SiO2 mixed matrix membrane provided by the present application will be described in detail below through embodiments.

[0026] The materials used in the following embodiments are commercially available, wherein Pebax-1657 is purchased from Arkema Company in France; tetrapropylammonium hydroxide (TPAOH) is purchased from Aldrich Chemical Company in the United States; 1-butyl-3-methylimidazolium tetrafluoroborate [Bmim][BF4] is purchased from Aldrich Chemical Company in the United States; tetraethyl orthosilicate (TEOS) is purchased from Aldrich Chemical Company in the United States.

[0027] Example 1

[0028] Step 1, Pebax-1657 and an ethanol aqueous solution were placed in a flask, and an oil bath was performed at 60℃ for 4 hours to obtain a uniform concentration of Pebax solution, wherein the mass ratio of Pebax-1657 to the ethanol aqueous solution was 1:7;

[0029] Step 2, white carbon black and tetrapropylammonium hydroxide were mixed uniformly to obtain a mixture, the mixture was added to an open glass container, and was transferred to the inner liner of a hydrothermal reaction kettle, 5 mL of deionized water was added outside the glass bottle mouth of the inner liner, and the packaged hydrothermal reaction kettle was crystallized at 135℃ for 6 hours to obtain a crystalline product, the product was centrifuged, washed, dried, and calcined to obtain Silicalite-1 nanocrystals, wherein the mass ratio of white carbon black to tetrapropylammonium hydroxide was 1:1;

[0030] Step 3. Silicalite-1 and ethanol were added to a round-bottom flask in a mass ratio of 1:10. After ultrasonication for 30 minutes, a mixed solution of tetraethyl orthosilicate and ethanol was added, and the mixture was heated at 60°C at a speed of 400 r / min for 2 hours. 1-butyl-3-methylimidazolium tetrafluoroborate was added and continued to heat for 5 hours. Concentrated hydrochloric acid was added dropwise until a gel state appeared. Stirring was stopped and aged at 25°C for 12 hours. The product was placed in a vacuum drying oven at 150°C and dried for 6 hours to obtain the target product, ionic liquid functionalized Silicalite-1@SiO2, which is a white powder. The above raw materials are calculated by mass ratio: Silicalite-1: tetraethyl orthosilicate: 1-butyl-3-methylimidazolium tetrafluoroborate: concentrated hydrochloric acid = 1:2:3:7;

[0031] Step 4: Functionalize the prepared ionic liquid into Silicalite-1@SiO 2加入 The mass ratio of the two in ethanol was 1:10, ultrasonically dispersed for 2 hours, and stirred at 400 r / min for 24 hours to obtain the ionic liquid functionalized Silicalite-1@SiO2 filler casting solution;

[0032] Step 5. Add the Pebax-1657 solution to the reagent bottle, and drop the ionic liquid functionalized Silicalite-1@SiO2 filler casting solution (mass ratio of 19:1) into it. Use a turbine oscillator to oscillate for 2 hours and ultrasonically treat for 10 minutes. After the filler and the polymer solution are evenly mixed, the casting solution is statically degassed; pour the prepared mixed matrix membrane solution onto a polytetrafluoroethylene plate, place it in a constant temperature oven at 60°C and dry it for 24 hours, and then place it in a vacuum oven at 60°C and dry it for 12 hours to obtain a mixed matrix membrane of ionic liquid functionalized Silicalite-1@SiO2.

[0033] exist Figure 2 In the XRD spectrum of the prepared Silicalite-1@SiO2 mixed matrix membrane, a small peak appeared at 2θ of 23.99°, proving that the prepared mixed matrix membrane contained Silicalite-1 nanocrystals. The lack of obvious peak position also proved that the outer layer of the Silicalite-1 nanocrystals was covered with SiO2 and impregnated with ionic liquid.

[0034] After testing, the ionic liquid functionalized Silicalite-1@SiO2 content of the above-mentioned mixed matrix membrane is 5wt.% MMMs, which exhibits CO2 permeability coefficient and CO2 / N2 selectivity. The CO2 permeability coefficient is 83.43 Barrer, and the CO2 / N2 selectivity is 71.55, which has good CO2 permeability and excellent CO2 / N2 selectivity.

[0035] Example 2:

[0036] Step 1, Pebax-1657 and aqueous ethanol solution were placed in a flask, and an oil bath was used at 60℃ for 4 hours to obtain a uniform concentration of Pebax solution, wherein the mass ratio of Pebax-1657 to aqueous ethanol solution was 1:7;

[0037] Step 2, the mixture was prepared by uniformly mixing white carbon black and tetrapropyl ammonium hydroxide, the mixture was added to an open glass container, and it was transferred to the inner liner of a hydrothermal reaction kettle, 5mL of deionized water was added outside the glass bottle mouth of the inner liner, and the crystalline product was obtained after the encapsulated hydrothermal reaction kettle was crystallized at 135℃ for 6 hours, the product was centrifuged, washed, dried, and calcined to obtain Silicalite-1 nanocrystals, wherein the mass ratio of white carbon black to tetrapropyl ammonium hydroxide was 1:1;

[0038] Step 3, Silicalite-1 and ethanol were added to a round-bottom flask in a mass ratio of 1:10, and then tetraethyl orthosilicate and ethanol were added to the mixture solution, which was heated at 60℃ for 2 hours at a rotation speed of 400r / min, and then 1-butyl-3-methyl imidazole tetrafluoroborate was added and heated for 5 hours, after which concentrated hydrochloric acid was added dropwise until a gel state appeared, and then the stirring was stopped, and the product was aged at 25℃ for 12 hours, and then dried in a vacuum drying oven at 150℃ for 6 hours to obtain a white powder target product, ionic liquid functionalized Silicalite-1@SiO2, the above raw materials were in a mass ratio of Silicalite-1: tetraethyl orthosilicate: 1-butyl-3-methyl imidazole tetrafluoroborate: concentrated hydrochloric acid = 1:2:3:7;

[0039] Step 4, the prepared ionic liquid functionalized Silicalite-1@SiO 2加入 Step 4, the prepared ionic liquid functionalized Silicalite-1@SiO

[0040] Step 5, Pebax-1657 solution was added to a reagent bottle, and ionic liquid functionalized Silicalite-1@SiO2 filler casting solution (mass ratio 9:1) was added dropwise, and then a turbine oscillator was used for oscillation for 2 hours and ultrasonic treatment for 10 minutes, and then the filler and the polymer solution were mixed uniformly, and the casting solution was left to deaerate; the prepared mixed matrix membrane solution was poured into a polytetrafluoroethylene flat plate, and then placed in a constant temperature oven at 60℃ for drying for 24 hours, and then placed in a vacuum oven at 60℃ for drying for 12 hours to obtain a mixed matrix membrane of ionic liquid functionalized Silicalite-1@SiO2.

[0041] In Figure 2The XRD spectrum of the prepared Silicalite-1@SiO2 mixed matrix membrane shows a small peak at 2θ of 23.99°, which proves that the prepared mixed matrix membrane contains Silicalite-1 nanocrystals, and the peak position is not obvious, which also proves that the outer layer of the Silicalite-1 nanocrystals grows SiO2 and is impregnated with an ionic liquid.

[0042] The above-mentioned mixed matrix membrane with a content of 10wt.% MMMs shows the best CO2 permeation coefficient, ionic liquid functionalized Silicalite-1@SiO2 and CO2 / N2 selectivity, CO2 permeation coefficient is 98.67 Barrer, CO2 / N2 selectivity is 78.28, with good CO2 permeability and excellent CO2 / N2 selectivity.

[0043] Example 3:

[0044] Step 1, put Pebax-1657 and ethanol aqueous solution into a flask, and heat in an oil bath at 60℃ for 4 hours to obtain a uniform concentration of Pebax solution, wherein the mass ratio of Pebax-1657 to ethanol aqueous solution is 1:7;

[0045] Step 2, mix the white carbon black and tetrapropylammonium hydroxide uniformly to obtain a mixture, add the mixture into an open glass container, and transfer it into the inner liner of a hydrothermal reaction kettle, add 5mL of deionized water outside the glass bottle mouth of the inner liner, and after crystallization treatment at 135℃ for 6 hours, obtain the crystallization product, centrifuge, wash, dry, and calcine the product to obtain Silicalite-1 nanocrystals, wherein the mass ratio of white carbon black to tetrapropylammonium hydroxide is 1:1;

[0046] Step 3, add Silicalite-1 and ethanol into a round-bottom flask at a mass ratio of 1:10, and after ultrasonic treatment for 30 minutes, add a mixed solution of tetraethyl orthosilicate and ethanol, heat at 60℃ at a speed of 400r / min for 2 hours, add 1-butyl-3-methylimidazolium tetrafluoroborate, continue to heat for 5 hours, then add concentrated hydrochloric acid dropwise until a gel state appears, stop stirring, and age at 25℃ for 12 hours, then put the product into a vacuum drying oven and dry at 150℃ for 6 hours to obtain the white powder target product ionic liquid functionalized Silicalite-1@SiO2, wherein the above-mentioned raw materials are in a mass ratio of Silicalite-1: tetraethyl orthosilicate: 1-butyl-3-methylimidazolium tetrafluoroborate: concentrated hydrochloric acid = 1:2:3:7;

[0047] Step 4, add the prepared ionic liquid functionalized Silicalite-1@SiO 2加入The mass ratio of the two in ethanol was 1:10, ultrasonically dispersed for 2 hours, and stirred at 400 r / min for 24 hours to obtain the ionic liquid functionalized Silicalite-1@SiO2 filler casting solution;

[0048] Step 5. Add the Pebax-1657 solution to the reagent bottle, and drop the ionic liquid functionalized Silicalite-1@SiO2 filler casting solution (mass ratio of 5.7:1) into it. Use a turbine oscillator to oscillate for 2 hours and ultrasonically treat for 10 minutes. After the filler and the polymer solution are evenly mixed, the casting solution is statically degassed; pour the prepared mixed matrix membrane solution onto a polytetrafluoroethylene plate, place it in a constant temperature oven at 60°C and dry it for 24 hours, and then place it in a vacuum oven at 60°C and dry it for 12 hours to obtain a mixed matrix membrane of ionic liquid functionalized Silicalite-1@SiO2.

[0049] exist Figure 2 In the XRD pattern of the prepared Silicalite-1@SiO2 mixed matrix membrane, the XRD spectrum shows a small peak at 2θ of 23.99°, proving that the prepared mixed matrix membrane contains Silicalite-1 nanocrystals. The peak position is not obvious, which also proves that the outer layer of the Silicalite-1 nanocrystals is covered with SiO2 and impregnated with ionic liquid. The peak position is slightly lower than that of Example 2 because the high content of filler will cause the particles to aggregate more easily in the matrix rather than be evenly dispersed, resulting in randomization of the crystal orientation, thereby weakening the XRD diffraction peak intensity of a specific crystal plane and lowering the peak position of the characteristic peak. It can be seen from Table 1 that the selectivity of Example 3 is lower than that of Example 2, which may also be due to its particle agglomeration phenomenon.

[0050] After testing, the content of the above-mentioned mixed matrix membrane was 15wt.% MMMs, which showed good CO2 permeability coefficient and CO2 / N2 selectivity. The CO2 permeability coefficient was 103.39 Barrer and the CO2 / N2 selectivity was 68.93.

[0051] Embodiment 4:

[0052] Step 1. Pebax-1657 and an ethanol aqueous solution are placed in a flask and incubated in an oil bath at 60° C. for 4 hours to obtain a Pebax solution of uniform concentration, wherein the mass ratio of Pebax-1657 to the ethanol aqueous solution is 1:7;

[0053] Step 2, the mixture of white carbon black and tetrapropyl ammonium hydroxide was prepared, the mixture was added to an open glass container, and the mixture was transferred to the inner liner of a hydrothermal reactor, 5 mL of deionized water was added outside the glass bottle mouth of the inner liner, and the packaged hydrothermal reactor was crystallized at 135 DEG C for 6 hours to obtain a crystalline product, the product was centrifuged, washed, dried, and calcined to obtain Silicalite-1 nanocrystals, wherein the mass ratio of white carbon black to tetrapropyl ammonium hydroxide is 1:1;

[0054] Step 3, Silicalite-1 and ethanol were added to a round-bottom flask in a mass ratio of 1:10, and then the mixture was ultrasonically treated for 30 minutes. A mixed solution of tetraethyl orthosilicate and ethanol was added, and the mixture was heated at 60 DEG C at a rotation speed of 400 r / min for 2 hours. 1-butyl-3-methylimidazolium tetrafluoroborate was added, and the mixture was heated for another 5 hours. Concentrated hydrochloric acid was added dropwise until a gel state appeared, and then the stirring was stopped. The product was aged at 20-30 DEG C for 12 hours, and then the product was dried in a vacuum drying oven at 150 DEG C for 6 hours to obtain a white powder target product, ionic liquid functionalized Silicalite-1@SiO2. The above raw materials were used in a mass ratio of Silicalite-1: tetraethyl orthosilicate: 1-butyl-3-methylimidazolium tetrafluoroborate: concentrated hydrochloric acid = 1:2:3:7.

[0055] Step 4, the prepared ionic liquid functionalized Silicalite-1@SiO 2加入 The ionic liquid functionalized Silicalite-1@SiO2filler casting solution was prepared by dispersing the ionic liquid functionalized Silicalite-1@SiO2filler in ethanol at a mass ratio of 1:10 for 2 hours, and stirring at 400 r / min for 24 hours.

[0056] Step 5, the Pebax-1657 solution was added to a reagent bottle, and the ionic liquid functionalized Silicalite-1@SiO2filler casting solution (mass ratio of 4:1) was added dropwise. The mixture was oscillated for 2 hours by using a turbine oscillator and ultrasonically treated for 10 minutes. After the filler and the polymer solution were uniformly mixed, the casting solution was left to stand for degassing. The prepared mixed matrix membrane solution was poured into a polytetrafluoroethylene flat plate, and then the flat plate was placed in a constant temperature oven at 60 DEG C for drying for 24 hours, and then the flat plate was placed in a vacuum oven at 60 DEG C for drying for 12 hours to obtain the mixed matrix membrane of ionic liquid functionalized Silicalite-1@SiO2.

[0057] In Figure 2In the XRD pattern of the prepared Silicalite-1@SiO2 mixed matrix membrane, the XRD spectrum shows a small peak at 2θ of 23.99°, proving that the prepared mixed matrix membrane contains Silicalite-1 nanocrystals. The lack of obvious peak position also proves that the outer layer of the Silicalite-1 nanocrystals is covered with SiO2 and impregnated with ionic liquid. The peak position is lower than that of Example 3 because a high content of filler causes the particles to aggregate more easily in the matrix rather than being evenly dispersed, resulting in randomization of the crystal orientation, thereby weakening the XRD diffraction peak intensity of a specific crystal plane and lowering the peak position of the characteristic peak. In addition, it can be seen from Table 1 that the selectivity of Example 4 is lower than that of the other examples, which also indirectly confirms this theory.

[0058] The content of the mixed matrix membrane was 20 wt.% MMMs, which showed good CO2 permeability and CO2 / N2 selectivity. The CO2 permeability was 115.64 Barrer and the CO2 / N2 selectivity was 58.34.

[0059] Comparative Example 1:

[0060] Preparation of pure Pebax-1657 mixed matrix membrane:

[0061] Pebax-1657:ethanol in a mass ratio of 1:7 was placed in a flask in an oil bath at 60°C for 4 hours to obtain a Pebax solution of uniform concentration. The solution was then ultrasonically degassed for 10 minutes, allowed to stand for 10 minutes, and then poured into a clean polytetrafluoroethylene mold. The membrane was then placed in a constant temperature oven and dried at 60°C for 24 hours. Finally, the membrane was vacuumed in a vacuum oven and dried at 60°C for 12 hours to obtain a pure Pebax-1657 mixed matrix membrane.

[0062] exist Figure 3 In the XRD pattern, the prepared pure Pebax-1657 mixed matrix membrane has an amorphous structure and therefore no characteristic peaks appear.

[0063] The separation performance of the mixed matrix membrane was tested to be P CO2 =65.98 Barrer, CO2 / N2 selectivity 57.24.

[0064] Comparative Example 2:

[0065] Preparation of Silicalite-1 / Pebax-1657 mixed matrix membrane

[0066] Pebax-1657:ethanol (mass ratio 1:7) was placed in a flask in an oil bath at 60°C for 4 hours to obtain a uniform concentration of Pebax solution, and Pebax-1657 solution was weighed into a reagent bottle, and 10 wt.% casting solution (Silicalite-1 nanocrystals prepared from Comparative Example 3 were added to ethanol, and after ultrasonic treatment for 2 hours, they were placed on a stirring table for stirring for 24 hours or more to obtain a Silicalite-1 filler casting solution), and the casting solution was mixed with the polymer solution by using a vortex oscillator for 4 hours and ultrasonic treatment for 10 minutes, and after the filler was uniformly mixed with the polymer solution, the casting solution was left to stand for degassing; the prepared mixed matrix membrane solution was poured onto a polytetrafluoroethylene flat plate, placed in a constant temperature oven at 60°C for drying for 24 hours, and then placed in a vacuum oven at 60°C for vacuuming to continue solvent removal for 12 hours to obtain a Silicalite-1 / Pebax mixed matrix membrane.

[0067] In the XRD pattern of Figure 3 The XRD spectrum of the prepared Silicalite-1 / Pebax mixed matrix membrane showed small peaks at 2θ of 7.96°, 8.83°, 23.99°, and 24.45°, proving that the prepared mixed matrix membrane contained Silicalite-1 nanocrystals.

[0068] The separation performance of the tested mixed matrix membrane was P CO2 = 75.26 Barrer, CO2 / N2 selectivity 58.08.

[0069] Comparative Example 3:

[0070] Silicalite-1 was synthesized by using TPAOH as a template for 6 hours

[0071] White carbon black and tetrapropylammonium hydroxide were weighed in a mass ratio of 1:1, and the tetrapropylammonium hydroxide was stirred until it was fully dissolved in the solvent, and then the white carbon black was added, and the reaction kettle was transferred to a 135°C oven for reaction for 6 hours, and then centrifuged, washed, dried, and calcined to obtain dry Silicalite-1 filler.

[0072] In the XRD pattern of Figure 3 The prepared Silicalite-1 nanocrystals had characteristic peaks at 2θ of 7.96°, 8.83°, 23.18°, 23.99°, and 24.45°, which were Silicalite-1 nanocrystals, and the baseline was flat, indicating that the Silicalite-1 seed had good crystallinity.

[0073] Comparative Example 4:

[0074] Synthesis of Silicalite-1 using TPAOH as a template agent for 1 hour

[0075] The white carbon black and tetrapropylammonium hydroxide were weighed according to the mass ratio of 1:1, and stirred under the action of the solvent until the tetrapropylammonium hydroxide was fully dissolved. Then the white carbon black was added, and transferred into a reaction kettle. After being aged at room temperature for 2 hours, the reaction kettle was transferred to a 135℃ oven for reaction for 1 hour. After centrifugal washing and drying, calcination was performed to obtain dry Silicalite-1 filler.

[0076] In the XRD spectrum of Figure 3 The prepared Silicalite-1 filler does not have obvious characteristic peaks, but shows a relatively wide and diffuse peak. This indicates that the atomic arrangement of the measured sample lacks long-range order and exhibits typical amorphous structure characteristics.

[0077] The XRD spectrum of Silicalite-1 shows an amorphous shape, indicating that the product is not crystallized.

[0078] The test results of the component distribution ratio, CO2 permeation coefficient (Barrer) and CO2 / N2 selectivity of the prepared ionic liquid functionalized Silicalite-1@SiO2-Pebax-1657 mixed matrix membrane are shown in Table 1.

[0079] Table 1

[0080] Filler content (wt%) CO2permeability coefficient (Barrer) CO2 / N2 selectivity Comparative Example 1 0 65.98 57.24 Comparative Example 2 10 75.26 58.08 Example 1 5 83.43 71.55 Example 2 10 98.67 78.28 Example 3 15 103.39 68.93 Example 4 20 115.64 58.34

[0081] Conclusion: From the performance chart of Table 1 and Figure 4 It can be seen from the performance chart of Table 1 and

[0082] The above is only a specific embodiment of the present application, which enables those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited.

Claims

1. A method for the preparation of an ionic liquid functionalized Silicalite-1@SiO2 mixed matrix membrane, characterized in that, Comprising the following steps: Step 1, put Pebax-1657 and aqueous ethanol solution into a flask, and heat in an oil bath at 60-80℃ for 4 hours to obtain a uniform concentration of Pebax-1657 solution, wherein the mass ratio of Pebax-1657 to aqueous ethanol solution is 1:7-32; Step 2, mix white carbon black and tetrapropylammonium hydroxide uniformly to obtain a mixture, add the mixture into an open glass container, and transfer it into the inner liner of a hydrothermal reaction kettle, add 2-20 mL of deionized water outside the glass bottle mouth of the inner liner, and obtain a crystalline product after crystallization treatment at 130-150℃ for 4-10 hours, centrifuge, wash, dry, and calcine the product to obtain Silicalite-1 nanocrystals, wherein the mass ratio of white carbon black to tetrapropylammonium hydroxide is 1:0.8-5; Step 3, add Silicalite-1 and ethanol into a round-bottom flask at a mass ratio of 1:10-100, and ultrasonic for 30-60 minutes, then add a mixed solution of tetraethyl orthosilicate and ethanol, heat at 60-80℃ at a speed of 400-600 r / min for 1-2 hours, add 1-butyl-3-methylimidazolium tetrafluoroborate and continue heating for 5-10 hours, then drop concentrated hydrochloric acid until a gel state appears, stop stirring, and age at 20-30℃ for 12-20 hours, then put the product into a vacuum drying oven and dry at 150℃ for 6-12 hours to obtain the target product ionic liquid functionalized Silicalite-1@SiO2 white powder, wherein the mass ratio of the above raw materials is Silicalite-1: tetraethyl orthosilicate: 1-butyl-3-methylimidazolium tetrafluoroborate: concentrated hydrochloric acid = 1:2-5:3-6:7-11; Step 4, add ionic liquid functionalized Silicalite-1@SiO2 into ethanol at a mass ratio of 1:10-50, ultrasonic for 2-4 hours, and stir at 400-600 r / min for 24-36 hours to obtain ionic liquid functionalized Silicalite-1@SiO2 filler casting solution; Step 5, add Pebax-1657 solution into a reagent bottle, drop ionic liquid functionalized Silicalite-1@SiO2 filler casting solution into it, oscillate for 2-4 hours using a vortex oscillator and ultrasonic for 10-20 minutes, mix the filler and polymer solution uniformly, and then let the casting solution stand for defoaming; pour the prepared mixed matrix membrane solution onto a polytetrafluoroethylene flat plate, put it into a constant temperature oven at 60-80℃ and dry for 18-24 hours, then put it into a vacuum oven and dry at 50-80℃ for 10-12 hours to obtain ionic liquid functionalized Silicalite-1@SiO2 mixed matrix membrane.

2. A process for the preparation of an ionic liquid functionalized Silicalite-1@Si02 hybrid matrix membrane as claimed in claim 1, wherein, The mass ratio of tetraethyl orthosilicate to ethanol in the mixed solution of step 3 is 1:1-5.

3. The method for preparing an ionic liquid functionalized Silicalite-1@SiO2 mixed matrix membrane according to claim 1, characterized in that: The mass ratio of ethanol to water in the aqueous ethanol solution of step 1 is 6-9:1-4.

4. The method for preparing an ionic liquid functionalized Silicalite-1@SiO2 mixed matrix membrane according to claim 1, characterized in that: The mass ratio of the Pebax-1657 solution in step 5 to the ionic liquid functionalized Silicalite-1@SiO2 filler casting solution is 4-20:

1.

5. The method according to any one of claims 1-4, wherein the method is characterized by, The mixed matrix membrane prepared is used for CO2 / N2 gas separation.

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