Preparation method and application of silicone rubber hollow fiber composite separation membrane

Abstract

The invention discloses a preparation method and application of a silicone rubber hollow fiber composite separation membrane, the preparation method takes hydroxyl-terminated methyl phenyl silicone oil and octyltrimethoxysilane as raw materials and supercritical carbon dioxide as a solvent, under the action of an organic tin catalyst, the silicon rubber hollow fiber composite separation membrane is prepared through a one-step method. And carrying out a cross-linking reaction on the hydroxyl-terminated methyl phenyl silicone oil and the octyltrimethoxysilane on the surface of the hollow fiber base membrane to form a separation layer so as to obtain the silicone rubber hollow fiber composite separation membrane. According to the invention, supercritical carbon dioxide carries raw materials of the separation layer to enter the hollow fiber membrane by virtue of strong dissolving capacity and high diffusion speed of non-polar compounds, so that coating of the separation layer in the hollow fiber membrane is realized, abrasion of the separation layer in the use process is avoided, and the composite separation membrane O2, O2 and O2 content is measured at 25 DEG C; and the permeation and separation properties of N2 are as follows: JN2 is greater than 0.3 m < 3 >. M <-2 >. Atm <-1 >. H <-1 >, and alpha (O2 / N2) is greater than 2.5, so that the method has an excellent application prospect.

Description

Technical Field

[0001] The present invention relates to the field of membrane separation technology, and more specifically, to a preparation method and application of a silicone rubber hollow fiber composite separation membrane. Background Art

[0002] The gas separation function of the membrane is to utilize the membrane's selective permeability to different gas components. The transmission rates of the components in the raw gas through the membrane are different under the pressure difference. The "slow gas" has a slower transmission rate and is retained on the raw gas side, while the "fast gas" has a faster transmission rate and is enriched on the other side of the membrane, thereby separating the different components in the raw gas. Since the 1830s, researchers have discovered that the membrane has different selective permeability rates for carbon dioxide and hydrogen through mixed gas permeation experiments, thus revealing that gas separation can be achieved with membranes. At present, based on the characteristics of membrane separation technology such as no pollution, low energy consumption, high separation efficiency, small equipment size, and arbitrary changes in scale and processing capacity, it has been applied in industrial production, environmental protection, biomaterials, etc.

[0003] Polymer membrane is the core of membrane gas separation process, and the development of high-performance gas separation membrane is of great significance. Composite membrane generally refers to asymmetric membrane. The base membrane and the separation functional layer are made of different materials. The base membrane is made of polymer or inorganic material and only has mechanical support. The separation is mainly completed by the functional material coated on the base membrane. Therefore, the production of composite membrane generally involves first making the base membrane, and then making the separation layer on the base membrane by solution coating and other methods. Silicone rubber is the polymer membrane material with the highest permeability since industrial application, and is often used as the separation layer of composite membrane. At present, there are three main types of composite membranes, flat membrane, tubular membrane, and hollow fiber membrane. Among them, the hollow fiber membrane has a self-supporting structure, a high packing density of the membrane assembly, a simple preparation process, and a good application prospect. Unlike the flat membrane, the separation layer can be coated on the inside or outside of the hollow fiber membrane. If the separation layer is coated on the outside, the operation is simple, but the separation layer is easily worn during use, resulting in a decrease in membrane selectivity or even damage. Therefore, it is of great significance to develop a method for coating the silicone rubber separation layer on the inside of the hollow fiber to make a composite separation membrane. Summary of the invention

[0004] The purpose of the present invention is to overcome the above-mentioned defects of the prior art and provide a preparation method and application of a silicone rubber hollow fiber composite separation membrane. Supercritical carbon dioxide is used as a solvent. By utilizing the strong solubility and high diffusion rate of supercritical carbon dioxide for non-polar compounds, the separation layer raw materials are carried into the interior of the hollow fiber membrane, thereby realizing the coating of the separation layer inside the hollow fiber membrane. Not only can a uniform coating be achieved, but also the use of volatile organic solvents can be avoided, thereby reducing VOCs emissions during the coating process of the composite membrane separation layer.

[0005] To achieve the above object, the technical solution of the present invention is as follows:

[0006] A preparation method of a silicone rubber hollow fiber composite separation membrane, wherein the preparation method uses terminal hydroxymethylphenyl silicone oil and octyltrimethoxysilane as raw materials, uses supercritical carbon dioxide as solvent, and under the action of an organic tin catalyst, causes the terminal hydroxymethylphenyl silicone oil and octyltrimethoxysilane to undergo a cross-linking reaction on the surface of a hollow fiber base membrane to form a separation layer, thereby obtaining a silicone rubber hollow fiber composite separation membrane; wherein the water flux of the hollow fiber membrane is greater than 12L / (m 2 *h), molecular weight cut-off is 25000-60000, BSA retention rate is >98%, inner diameter is 0.8mm-1mm, outer diameter is <1.4mm.

[0007] Optionally, the method specifically includes: dissolving terminal hydroxymethylphenyl silicone oil, octyltrimethoxysilane and organic tin catalyst in supercritical carbon dioxide, adding hollow fiber base membrane and mixing at 40℃~60℃ (preferably 45℃), 1000r / min~1400r / min (preferably stirring speed 1400r / min) for 1h~2h, then heating to 80℃~90℃ and curing for 1h~3h, preferably the curing temperature is 90℃, to obtain the silicone rubber hollow fiber composite separation membrane.

[0008] Optionally, the ratio of the sum of the masses of the terminal hydroxymethylphenyl silicone oil and the octyltrimethoxysilane to the surface area of ​​the hollow fiber base membrane is 2 g / m2 to 4 g / m2.

[0009] Optionally, the mass ratio of the octyltrimethoxysilane to the terminal hydroxymethylphenyl silicone oil is (1-2):5, and the preferred mass ratio is 1.8:5.

[0010] Optionally, the mass of the organic tin catalyst is 4‰ to 1% of the mass of the terminal hydroxymethylphenyl silicone oil, and the preferred mass ratio is 8‰.

[0011] Optionally, the system pressure of the supercritical carbon dioxide is 12 MPa to 20 MPa, preferably the system pressure is 20 MPa.

[0012] Optionally, the hollow fiber-based membrane includes at least one of a polysulfone hollow fiber-based membrane, a polyimide hollow fiber-based membrane, a polyetherimide hollow fiber-based membrane, a polyacrylamide hollow fiber-based membrane and a polyacrylonitrile hollow fiber membrane.

[0013] Optionally, the molar ratio of methyl group to phenyl group in the terminal hydroxymethylphenyl silicone oil is 1:1.

[0014] Optionally, the viscosity of the terminal hydroxymethylphenyl silicone oil is 1000 cst to 3000 cst.

[0015] Optionally, the organotin catalyst includes dibutyltin dilaurate and / or dioctyltin dilaurate.

[0016] The invention also discloses an application of the silicone rubber hollow fiber composite separation membrane prepared by the above-mentioned preparation method in separating oxygen and nitrogen.

[0017] Implementing the embodiments of the present invention will have the following beneficial effects:

[0018] The present invention provides a preparation method of a silicone rubber hollow fiber composite separation membrane. Supercritical carbon dioxide is used as a solvent. The supercritical carbon dioxide is used to carry a separation layer raw material. The supercritical carbon dioxide is used to carry the separation layer raw material into the hollow fiber membrane by utilizing the strong solubility and high diffusion rate of the supercritical carbon dioxide for non-polar compounds. The separation layer is coated inside the hollow fiber membrane, and the wear of the separation layer during use is avoided, thereby extending the service life. The prepared silicone rubber hollow fiber composite separation membrane can be used for separation of oxygen and nitrogen, recovery of organic vapors such as ethylene, propylene, gasoline, and permeation gasification. The composite separation membrane has O2 and N2 permeation and separation properties of J, J and J, respectively, as measured at 25°C. N2 >0.3m 3 ·m -2 ·atm -1 ·h -1 , α(O2 / N2)>2.5, which has excellent application prospects. DETAILED DESCRIPTION

[0019] The present invention will be described below with specific examples, but the protection scope of the present invention is not limited to these examples. The experimental methods used in the following examples are conventional methods unless otherwise specified; the materials, reagents, etc. used in the following preparation examples and examples can be obtained from commercial channels unless otherwise specified. The terminal hydroxymethylphenyl silicone oil selected in the examples of the present invention is from Guangzhou Jiahao Chemical Technology Co., Ltd.

[0020] Example 1

[0021] A method for preparing a silicone rubber hollow fiber composite separation membrane comprises the following steps:

[0022] 1000cst 300g of terminal hydroxymethylphenyl silicone oil (the molar ratio of methyl to phenyl is 1:1), 60g of octyltrimethoxysilane, 3g of dibutyltin dilaurate, polysulfone hollow fiber membrane (pure water flux 16.5L / (m 2h), molecular weight cutoff 30000) was added to the autoclave, and liquid carbon dioxide was added from a cylinder. The autoclave was heated to 40°C, and carbon dioxide was added to 12MPa through a liquid adding pump, and stirred at 1000r / min for 1h, and then the system temperature was further increased to 80°C for curing for 1h, so that the separation layer was coated inside the hollow fiber membrane under the supercritical carbon dioxide system, and a silicone rubber hollow fiber composite separation membrane was obtained.

[0023] Example 2

[0024] A method for preparing a silicone rubber hollow fiber composite separation membrane comprises the following steps:

[0025] 1500cst 400g of terminal hydroxymethylphenyl silicone oil (the molar ratio of methyl to phenyl is 1:1), 160g of octyltrimethoxysilane, 1.6g of dibutyltin dilaurate, and polyetherimide hollow fiber membrane (pure water flux 14.5L / (m 2 h), molecular weight cutoff 45000) was added to the autoclave, and liquid carbon dioxide was added from a cylinder. The autoclave was heated to 50°C, and carbon dioxide was added to 14MPa through a liquid adding pump. After stirring at 1000r / min for 1h, the system temperature was further increased to 85°C for curing for 1h, so that the separation layer was coated inside the hollow fiber membrane under the supercritical carbon dioxide system, and a silicone rubber hollow fiber composite separation membrane was obtained.

[0026] Example 3

[0027] A method for preparing a silicone rubber hollow fiber composite separation membrane comprises the following steps:

[0028] 2500cst 500g of terminal hydroxymethylphenyl silicone oil (the molar ratio of methyl to phenyl is 1:1), 180g of octyltrimethoxysilane, 4g of dioctyltin dilaurate, polyacrylamide hollow fiber membrane (pure water flux 20.1L / (m 2 h), molecular weight cut-off 60000) was added to the autoclave, and liquid carbon dioxide was added from a cylinder. The autoclave was heated to 50°C, and carbon dioxide was added to 16MPa through a liquid adding pump. After stirring at 1000r / min for 1h, the system temperature was further increased to 90°C for curing for 1h, so that the separation layer was coated inside the hollow fiber membrane under the supercritical carbon dioxide system, and a silicone rubber hollow fiber composite separation membrane was obtained.

[0029] Example 4

[0030] A method for preparing a silicone rubber hollow fiber composite separation membrane comprises the following steps:

[0031] 500 g of 3000 cst of terminal hydroxymethylphenyl silicone oil (the molar ratio of methyl to phenyl is 1:1), 100 g of octyltrimethoxysilane, 5 g of dioctyltin dilaurate, and a polyimide hollow fiber membrane (pure water flux 12.4 L / (m 2 h), molecular weight cutoff 25000) was added to the autoclave, and liquid carbon dioxide was added from a cylinder. The autoclave was heated to 40°C, and carbon dioxide was added to 18MPa through a liquid adding pump. After stirring at 1000r / min for 1h, the system temperature was further increased to 90°C for curing for 1h, so that the separation layer was coated inside the hollow fiber membrane under the supercritical carbon dioxide system, and a silicone rubber hollow fiber composite separation membrane was obtained.

[0032] Example 5

[0033] A method for preparing a silicone rubber hollow fiber composite separation membrane comprises the following steps:

[0034] 1500cst 300g of terminal hydroxymethylphenyl silicone oil (the molar ratio of methyl to phenyl is 1:1), 120g of octyltrimethoxysilane, 1.2g of dibutyltin dilaurate, and polyacrylonitrile hollow fiber membrane (pure water flux 12.4L / (m 2 h), molecular weight cutoff 25000) was added to the autoclave, and liquid carbon dioxide was added from a cylinder. The autoclave was heated to 60°C, and carbon dioxide was added to 18MPa through a liquid adding pump, and stirred at 1000r / min for 2h, and then the system temperature was further increased to 90°C for curing for 1h, so that the separation layer was coated inside the hollow fiber membrane under the supercritical carbon dioxide system, and a silicone rubber hollow fiber composite separation membrane was obtained.

[0035] Example 6

[0036] A method for preparing a silicone rubber hollow fiber composite separation membrane comprises the following steps:

[0037] 1000cst 400g of terminal hydroxymethylphenyl silicone oil (the molar ratio of methyl to phenyl is 1:1), 80g of octyltrimethoxysilane, 3.2g of dibutyltin dilaurate, and polyacrylonitrile hollow fiber membrane (pure water flux 12.4L / (m 2 h), molecular weight cutoff 25000) was added to the autoclave, and liquid carbon dioxide was added from a cylinder. The autoclave was heated to 60°C, and carbon dioxide was added to 20MPa through a liquid adding pump, and the reaction was stirred at 1000r / min for 1h, and the system temperature was further increased to 90°C for curing for 1h, so that the separation layer was coated inside the hollow fiber membrane under the supercritical carbon dioxide system, and a silicone rubber hollow fiber composite separation membrane was obtained.

[0038] Example 7

[0039] A method for preparing a silicone rubber hollow fiber composite separation membrane comprises the following steps:

[0040] 500 g of 3000 cst of terminal hydroxymethylphenyl silicone oil (the molar ratio of methyl to phenyl is 1:1), 150 g of octyltrimethoxysilane, 2 g of dibutyltin dilaurate, and a polyimide hollow fiber membrane (pure water flux 35.4 L / (m 2 h), molecular weight cutoff 25000) was added to the autoclave, and liquid carbon dioxide was added from a cylinder. The autoclave was heated to 60°C, and carbon dioxide was added to 20MPa through a liquid adding pump, and stirred at 1000r / min for 2h, and then the system temperature was further increased to 80°C for curing for 1h, so that the separation layer was coated inside the hollow fiber membrane under the supercritical carbon dioxide system, and a silicone rubber hollow fiber composite separation membrane was obtained.

[0041] Embodiment 8-11

[0042] Compared with Example 3, the difference between Example 8-11 is that the mass ratio of octyltrimethoxysilane and terminal hydroxymethylphenyl silicone oil is changed. Except for the above differences, other operations are the same and will not be repeated here; the mass ratios of octyltrimethoxysilane and terminal hydroxymethylphenyl silicone oil in Examples 8-11 are 1:10, 1:5, 2:5, and 4:5, respectively.

[0043] Examples 12-15

[0044] The difference between Examples 12-15 and Example 3 is that the amount of the organic tin catalyst added is changed. Except for the above differences, other operations are the same and will not be repeated here. The amount of the organic tin catalyst added in Examples 12-15 corresponds to 2‰, 4‰, 1%, and 1.2%, respectively.

[0045] Examples 16-19

[0046] The difference between Examples 16-18 and Example 3 is that the reaction pressure is changed. Except for the above differences, other operations are the same and will not be repeated here. The reaction pressures in Examples 16-18 correspond to 10MPa, 12MPa, 20MPa, and 24MPa, respectively.

[0047] Examples 20-22

[0048] The difference between Examples 20-22 and Example 3 is that the curing temperature is changed. Except for the above differences, other operations are the same and will not be repeated here. The curing temperatures in Examples 19-20 correspond to 70°C, 80°C, and 100°C, respectively.

[0049] Performance Testing

[0050] The composite separation membrane prepared in the embodiment was tested for permeation rate and separation coefficient. The specific test process was as follows: a membrane of fixed size was placed in a steel sample cell, nitrogen at a certain pressure was passed into the sample cell, and the volume of nitrogen passing through the membrane per unit time was measured to obtain the nitrogen permeation rate; oxygen and nitrogen were configured into a mixed gas with a certain molar concentration ratio, and the composition of the mixed gas after passing through the membrane was tested. The ratio of the molar concentration of oxygen after the membrane and before the membrane was divided by the ratio of the molar concentration of nitrogen after the membrane and before the membrane to obtain the separation coefficient of oxygen and nitrogen of this membrane. The experimental results are shown in Table 1.

[0051] Table 1 Comparison of separation performance of the embodiments

[0052] <![CDATA[Permeation rate J N2 / m 3 ·m -2 ·atm -1 ·h -1 > <![CDATA[Separation coefficient α(O2 / N2)]]> Example 1 0.304 2.29 Example 2 0.294 2.3 Example 3 0.313 2.41 Example 4 0.267 2.35 Example 5 0.252 2.37 Example 6 0.28 2.34 Example 7 0.261 2.33 Example 8 0.295 1.95 Example 9 0.305 2.27 Example 10 0.243 2.36 Embodiment 11 0.22 2.02 Example 12 0.332 1.85 Embodiment 13 0.283 2.3 Embodiment 14 0.254 2.32 Embodiment 15 0.233 2.07 Example 16 0.406 1.77 Embodiment 17 0.335 2.07 Embodiment 18 0.263 2.36 Embodiment 19 0.323 1.86 Embodiment 20 0.336 1.98 Embodiment 21 0.321 2.24 Embodiment 22 0.132 2.27

[0053] It can be seen from the analysis that the gas separation characteristics of the embodiments within the scope of the present invention are significantly changed, and the gas separation characteristics are significantly improved.

[0054] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for preparing a silicone rubber hollow fiber composite separation membrane, characterized in that: The preparation method uses terminal hydroxymethylphenyl silicone oil and octyltrimethoxysilane as raw materials and supercritical carbon dioxide as solvent. Under the action of an organic tin catalyst, the terminal hydroxymethylphenyl silicone oil and octyltrimethoxysilane undergo a cross-linking reaction on the surface of a hollow fiber base membrane to form a separation layer, thereby obtaining a silicone rubber hollow fiber composite separation membrane; wherein the water flux of the hollow fiber membrane is greater than 12L / (m 2 *h), molecular weight cut-off is 25000-60000, BSA retention rate is >98%, inner diameter is 0.8mm-1mm, outer diameter is <1.4mm.

2. The method for preparing a silicone rubber hollow fiber composite separation membrane according to claim 1, characterized in that: The method specifically comprises: After dissolving terminal hydroxymethylphenyl silicone oil, octyltrimethoxysilane and organic tin catalyst in supercritical carbon dioxide, adding the hollow fiber base membrane and mixing at 40°C to 60°C and 1000r / min to 1400r / min for 1h to 2h, then heating to 80°C to 90°C and curing for 1h to 3h to obtain the silicone rubber hollow fiber composite separation membrane.

3. The method for preparing a silicone rubber hollow fiber composite separation membrane according to claim 2, characterized in that: The ratio of the sum of the masses of the terminal hydroxymethylphenyl silicone oil and the octyltrimethoxysilane to the surface area of ​​the hollow fiber base membrane is 2 g / m2 to 4 g / m2.

4. The method for preparing a silicone rubber hollow fiber composite separation membrane according to claim 2, characterized in that: The mass ratio of the octyl trimethoxy silane to the terminal hydroxy methyl phenyl silicone oil is (1-2):5; The mass of the organic tin catalyst is 4‰ to 1% of the mass of the terminal hydroxymethylphenyl silicone oil.

5. The method for preparing a silicone rubber hollow fiber composite separation membrane according to claim 2, characterized in that: The system pressure of the supercritical carbon dioxide is 12MPa to 20MPa.

6. The method for preparing a silicone rubber hollow fiber composite separation membrane according to claim 2, characterized in that: The hollow fiber-based membrane includes at least one of a polysulfone hollow fiber-based membrane, a polyimide hollow fiber-based membrane, a polyetherimide hollow fiber-based membrane, a polyacrylamide hollow fiber-based membrane, and a polyacrylonitrile hollow fiber-based membrane.

7. The method for preparing a silicone rubber hollow fiber composite separation membrane according to claim 2, characterized in that: The molar ratio of methyl to phenyl in the terminal hydroxy methyl phenyl silicone oil is 1:

1.

8. The method for preparing a silicone rubber hollow fiber composite separation membrane according to claim 2, characterized in that: The viscosity of the terminal hydroxymethylphenyl silicone oil is 1000 cst to 3000 cst.

9. The method for preparing a silicone rubber hollow fiber composite separation membrane according to claim 2, characterized in that: The organotin catalyst includes dibutyltin dilaurate and / or dioctyltin dilaurate.

10. Use of a silicone rubber hollow fiber composite separation membrane prepared by the preparation method according to any one of claims 1 to 9 in separating oxygen and nitrogen.