Armor desorption membrane, preparation method thereof and application of armor desorption membrane in removal of CO2 in low-temperature methanol washing solvent

Abstract

The invention discloses an armor desorption membrane, a preparation method of the armor desorption membrane and application of the armor desorption membrane to removal of CO2 in a low-temperature methanol washing solvent, and belongs to the technical field of membrane separation. The armor desorption membrane is a composite structure hollow fiber membrane obtained by spinning through a three-channel nozzle; the composite structure hollow fiber membrane sequentially comprises a separation layer, a porous layer and a hollow cavity defined by the porous layer from outside to inside, the separation layer is of an asymmetric structure, the side, away from the porous layer, of the separation layer is a compact skin layer, and the thickness of the compact layer is 1-3 microns, so that the desorption film has a long-term solvent tolerance armor effect, and meanwhile, the desorption film can also be endowed with a relatively high CO2 permeation rate. The armor desorption membrane can replace an N2 gas stripping process in traditional low-temperature methanol washing, and is used for removing CO2 dissolved in methanol from methanol so as to realize solvent regeneration. The replacement of N2 gas stripping by membrane desorption is subversive improvement, the purity of CO2 can be remarkably improved while the energy consumption is greatly reduced, direct emission is avoided, and energy conservation and emission reduction are realized at the same time.

Description

Technical Field

[0001] The present application relates to an armor desorption membrane, a preparation method thereof, and an application in removing CO2 from a low-temperature methanol washing solvent, belonging to the technical field of membrane separation. Background Art

[0002] The Rectisol Process is a gas purification method jointly developed by Linde and Lurgi companies in Germany in the 1950s. It is widely used in the coal gasification process of C1 chemical industry, covering multiple coal chemical fields such as coal-to-synthesis gas, coal-to-ammonia, coal-to-hydrogen, and coal-to-methanol. The principle of the Rectisol Process is to use cold methanol as the absorption solvent. Utilizing the characteristic that methanol has extremely high solubility for acidic gases under low-temperature and high-pressure conditions, acidic impurity gases in the raw material gas are absorbed, and the absorbed acidic gases are separately desorbed and recovered according to the difference in solubility of different acidic gases.

[0003] In the Rectisol Process, the absorbed rich liquid is depressurized in two stages and then N2 gas stripping is used to desorb the dissolved CO2. The purpose of desorption is to realize the integrated absorption-desorption cycle operation of the CO2 absorption and separation device through the regeneration of the absorbent, thereby reducing the usage amount of the absorption liquid and improving the economy of the system. The energy consumption of the desorbed N2 in terms of standard coal accounts for a relatively high proportion in the overall energy consumption of the Rectisol Process; moreover, the CO2 content in the desorbed gas generated by the stripping process is only about 70-80%, and the purity is relatively low and cannot be directly utilized.

[0004] Energy conservation and consumption reduction of the common production unit Rectisol is the key to the low-carbon development of coal chemical industry. Therefore, carrying out a disruptive improvement on the existing N2 stripping process, on the one hand, reducing the process energy consumption and increasing the CO2 purity to a utilizable level to avoid pollution caused by emissions to the atmosphere, can simultaneously achieve the goal of energy conservation and emission reduction, which is of extremely important significance.

[0005] Membrane desorption is a very promising method for desorbing CO2-rich liquid developed in recent years. In the prior art, the mass transfer process of separating specific gas components dissolved in a liquid by using the membrane desorption process has been analyzed. In the membrane desorption process, mass transfer between the gas and liquid phases is achieved without direct contact. The membrane material is generally selected as a hydrophobic porous hollow fiber membrane. Therefore, the membrane medium does not play a separation performance role, but only acts as an interface between the two phases to separate the gas and liquid phases. Generally, a carrier gas is used for purging or vacuum pumping on the gas phase side. The gas dissolved in the liquid can be desorbed from the liquid under the drive of the concentration gradient, pass through the membrane contact interface, and enter the gas phase main body to achieve separation. As a mass transfer / separation device, the hollow fiber membrane contactor has the advantages of a large mass transfer specific surface area, simple amplification, and flexible series and parallel connection, making the CO2 membrane desorption technology have a series of advantages in terms of mass transfer performance, operating conditions, energy consumption, etc. In addition, most traditional desorption devices have operation problems such as entrainment of liquid droplets, foaming, and flooding. However, in the process of separating CO2 by membrane desorption, the gas and liquid phases are independent of each other and do not have direct contact. Therefore, by adjusting the operating conditions of the gas and liquid phases, the above problems can be effectively solved.

[0006] For the porous membranes such as polytetrafluoroethylene, polypropylene, and polyvinylidene fluoride used in the conventional membrane desorption process, their breakthrough pressures for the polar small molecule organic solvent methanol are extremely low. When the CO2-rich solution after low-temperature methanol washing enters the stripping column, it still has a certain pressure. Therefore, if a porous membrane is used, the liquid will directly pass through the membrane pores, making the membrane desorption process unable to be completed; methanol, as a small molecule polar solvent, has a swelling effect on the membrane material. Therefore, a material with a low methanol swelling rate must be selected; moreover, the conventional method of preparing an asymmetric membrane by the phase inversion method and applying a silicone rubber coating to improve the separation performance is no longer applicable because silicone rubber cannot withstand methanol for a long time. Therefore, an armor desorption membrane with a dense separation layer must be directly prepared, that is, this membrane not only has the function of permeating and desorbing CO2, but also must play the role of armor to protect the desorption membrane to operate stably for a long time. Summary of the Invention

[0007] The inventors found that from the perspective of desorption performance, the prepared desorption membrane should be an asymmetric composite structure. On the premise of realizing the armor protection function, the dense skin layer of the separation layer should be as thin as possible to increase the CO2 permeation rate, and at the same time, it should be in the form of a hollow fiber membrane to achieve large-area loading and large-scale application. In summary, the desorption membrane applicable to the regeneration process of the carbon solvent in low-temperature methanol washing should be: a hollow fiber membrane with a solvent-resistant armor layer, an asymmetric composite structure, and high CO2 permeability.

[0008] To solve the problem that traditional porous membranes cannot be used in the process of low-temperature methanol washing for CO2 membrane desorption and solvent regeneration because of methanol permeation, and silicone rubber-coated membranes cannot withstand methanol swelling, this application proposes a preparation method of a hollow fiber desorption membrane with a solvent-resistant armor layer, an asymmetric composite structure, and high CO2 permeability. The prepared armor desorption membrane can be stably and efficiently applied to the process of low-temperature methanol washing membrane desorption solvent regeneration for a long time, with obvious technical advantages.

[0009] This application adopts the following technical solutions:

[0010] According to the first aspect of this application, an armor desorption membrane is provided, and the armor desorption membrane is a composite structure hollow fiber membrane;

[0011] The composite structure hollow fiber membrane sequentially includes a separation layer, a porous layer, and a hollow cavity surrounded by the porous layer from the outside to the inside;

[0012] The separation layer has an asymmetric structure, and the side facing away from the porous layer is a dense skin layer.

[0013] Optionally, the thickness of the dense layer in the separation layer is 1-3 μm;

[0014] The thickness of the separation layer is 100-300 μm;

[0015] The thickness of the porous layer is 100-300 μm;

[0016] The materials of the separation layer and the porous layer are independently selected from at least one of polyimide, polyetherimide, cellulose, cellulose acetate, polysulfone, polyphenylsulfone, and polyvinylidene fluoride.

[0017] In this application, the separation function of the armor desorption membrane is realized by the outer surface separation layer, more precisely by the dense skin layer of the separation layer; the porous layer only plays a mechanical support role and provides pressure resistance for the composite membrane; the membrane materials of the separation layer and the porous layer in this armor desorption membrane can be the same or different. Considering that the porous layer only provides mechanical support for the armor desorption membrane, membrane materials with low prices such as polysulfone and cellulose acetate are preferably used to reduce costs.

[0018] To ensure no methanol leakage during the membrane desorption process, the dense skin layer of the separation layer must be a defect-free structure directly prepared by phase inversion, without subsequent coating to block pores; at the same time, considering the gas permeability, the thickness range of its dense skin layer should be controlled at 1.00-3.00 μm.

[0019] According to the second aspect of this application, a preparation method of the above-mentioned armor desorption membrane is provided, including the following steps:

[0020] S1. Prepare a casting solution for the separation layer, a casting solution for the porous layer, and a core liquid respectively;

[0021] S2. A three-channel nozzle co-extrusion method is used to spin the separation layer casting liquid, the porous layer casting liquid and the core liquid to form a primary hollow fiber membrane, the primary membrane is purged through an air chamber, and then enters a gel bath to phase-transform into a membrane, thereby obtaining the armor desorption membrane.

[0022] A gear pump is used to accurately control the flow of two sets of casting liquids; a plunger pump is used to control the flow of the core liquid. After leaving the nozzle, the primary membrane passes through a gas chamber with controlled temperature and N2 flow, then enters a gel bath for phase transformation into a membrane, and finally, after solvent removal and drying steps, an armor desorption membrane is obtained.

[0023] Optionally, the separation layer casting solution includes a low boiling point component;

[0024] The low boiling point component is selected from at least one of methanol, ethanol and tetrahydrofuran.

[0025] Optionally, the casting solution of the porous layer includes a pore-forming agent;

[0026] The pore-forming agent is selected from at least one of polyvinyl pyrrolidone, sodium chloride, potassium chloride, polyethylene glycol, and polyvinyl alcohol.

[0027] Optionally, the core liquid comprises water and a solvent, wherein the concentration of the solvent is 0 to 90.0 wt %, preferably 50.0 wt %.

[0028] Optionally, the concentration of the separation layer material in the separation layer casting solution is 30.0-45.0 wt %, preferably 40.0 wt %.

[0029] Optionally, the concentration of the porous layer material in the casting solution of the porous layer is 15.0-30.0 wt %, preferably 25.0 wt %.

[0030] Optionally, the solvents in the separation layer casting liquid, the porous layer casting liquid and the core liquid are independently selected from at least one of N-methylpyrrolidone, ethyl acetate, methyl ethylene glycol, ethylene glycol phenyl ether and dimethylacetamide; the two groups of casting liquids preferably have the same solvent.

[0031] Optionally, the concentration of the low boiling point component in the separation layer casting solution is 0 to 10.0 wt %, preferably 5.0 wt %.

[0032] Optionally, the concentration of the pore-forming agent in the casting solution of the porous layer is 0 to 15.0 wt %, preferably 8.0 wt %.

[0033] Optionally, during the spinning process, the temperatures of the separation layer casting solution, the porous layer casting solution and the core solution are independently controlled to be 20-100°C, preferably 70.0°C.

[0034] Optionally, the flow rate ratio of the casting solution for the separation layer to the casting solution for the porous layer is 0.1 to 10.0; the flow rates of the casting solution for the separation layer and the casting solution for the porous layer are controlled by gear pumps. Preferably, the flow rate ratio of the two casting solutions is controlled to be 0.5.

[0035] Optionally, the flow rate ratio of the core liquid to the casting solution for the porous layer is 0.1 to 10.0; the flow rate of the core liquid is controlled by a plunger pump, and the flow rate ratio of the plunger pump to the casting solution for the porous layer is controlled to be 0.1 to 10.0, preferably 0.3.

[0036] Optionally, the spinning rate is 0 to 3000 m / hr. Preferably 1500 m / hr.

[0037] Optionally, the spinning process includes: feeding the casting solution for the separation layer, the casting solution for the porous layer, and the core liquid into the outermost layer, the middle layer, and the inner hole of a three-channel nozzle respectively. Inside the nozzle, the casting solution for the separation layer contacts and merges with the casting solution for the porous layer, and then leaves the nozzle in the form of a nascent hollow fiber membrane.

[0038] Optionally, the conditions for purging the nascent membrane through an air chamber include: the length of the purging space in the air chamber is 0 to 50.0 cm, the purging gas is nitrogen, the temperature of the purging gas is 20.0 to 100.0 °C, and the flow rate of the purging gas is 0 to 1000 ml / min.

[0039] Optionally, the length of the purging space in the air chamber is preferably 10.0 cm, the temperature of the purging gas is preferably 70.0 °C, and the flow rate of the purging gas is preferably 200 ml / min.

[0040] During the process of purging the nascent membrane through the air chamber, after the nascent membrane leaves the nozzle, it enters the air chamber for purging, that is, enters the dry spinning stage. The length of the dry spinning stage is controlled within 0 to 50.0 cm. In fact, the outer surface of the casting solution for the separation layer is still in a homogeneous state when it leaves the nozzle. In the dry spinning stage, by forcibly purging the surface of the nascent membrane, because the temperature of the membrane solution extruded from the nozzle is relatively high, purging will promote the volatilization of low-boiling components and some solvents on the outer surface in contact with air to increase the polymer concentration on the outer surface of the membrane. That is, by controlling the temperature and flow rate of the purging gas, it forms the main control stage for the thickness of the dense skin layer of the separation layer. That is, the dense skin layer of the separation membrane is formed by forcibly purging to increase the polymer concentration on the outer surface of the membrane, and is supplemented by the subsequent liquid-liquid phase separation of the solvent and non-solvent after entering the gel bath, and finally forms an asymmetric structure with the porous layer after solidification.

[0041] Optionally, the conditions for phase inversion and film formation after entering the gel bath include: the gel bath is selected from water and / or ethanol, and the temperature of the gel bath is 0 to 100.0 °C; preferably 20.0 °C.

[0042] Optionally, the concentration of ethanol in the gel bath is 0 to 100.0 wt%; preferably 50.0 wt%.

[0043] Optionally, after the phase transformation and film formation in the gel bath, it further includes washing, wire winding, and drying.

[0044] In this application, after the nascent hollow fiber membrane goes through the dry spinning stage, it enters the gel bath. The gel bath is tap water, ethanol, or a mixture thereof. After solidifying into a film through the gel bath, it enters the water washing tank, and the temperature is controlled at 0 to 100.0 °C, preferably 20.0 °C; then the film is wound and collected on a wire winding wheel; the prepared armor desorption membrane must be placed in flowing water for washing to fully remove the residual solvent therein, and the water temperature is controlled at 0 to 100.0 °C, preferably 60.0 °C; the washing time is controlled at 0 to 240 hr, preferably 120 hr; after the washing is completed, the film is placed in an oven for drying, and the drying temperature is controlled at 0 to 120.0 °C, preferably 105.0 °C; the drying time is controlled at 0 to 10 hr, preferably 2 hr.

[0045] According to the second aspect of this application, there is provided an application of the above-mentioned armor desorption membrane or the armor desorption membrane obtained according to the above-mentioned preparation method in removing CO2 from the low-temperature methanol washing solvent;

[0046] Optionally, the application includes placing the armor desorption membrane in bundles in a membrane shell and sealing both ends with epoxy to prepare a desorption membrane module.

[0047] The armor desorption membrane can be placed in bundles in a membrane shell and sealed at both ends with epoxy. The desorption membrane module can be used to replace the low-temperature methanol washing N2 gas stripping process to separate the CO2 dissolved in methanol by membrane desorption to regenerate the solvent.

[0048] The beneficial effects of this application include:

[0049] The armor desorption membrane provided by the present application for CO2 removal in the low-temperature methanol washing solvent has a double-layer composite structure compared with the porous membrane used in traditional membrane desorption, ensuring its good pressure resistance; it has a dense armor layer to ensure no large amount of methanol permeation during the regeneration of the methanol solvent; the thickness of the dense skin layer is relatively thin, controlled within 1.00 - 3.00 μm, which not only plays the role of an armor with long-term tolerance to solvents to prevent methanol permeation but also ensures a high CO2 desorption and permeation flux; the composite configuration can use low-cost membrane materials in the porous layer, greatly reducing the application cost of the desorption membrane; the hollow fiber membrane configuration enables the armor desorption membrane involved in the present invention to have the potential for large-area loading and large-scale application. The armor desorption membrane and its components involved in the present invention can replace the N2 stripping process in traditional low-temperature methanol washing when the armor desorption membrane is applied to the low-temperature methanol washing process, and are used to remove the CO2 dissolved in methanol to realize solvent regeneration. Replacing N2 stripping with membrane desorption is a subversive improvement. While avoiding the waste of N2 resources and significantly reducing the process energy consumption, the CO2 concentration in the gas generated by membrane desorption is much higher than that of the stripping process, which can significantly improve the CO2 purity and avoid the pollution caused by direct emission into the atmosphere, and at the same time achieve energy conservation and emission reduction, with obvious technical advantages. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 It is a schematic diagram of a three-channel spinning nozzle, where (a) is a physical photo of the three-channel nozzle (the upper figure is a side view, and the lower figure is a cross-sectional view), (b) is a schematic diagram of the three-channel nozzle structure, and (c) is a physical photo of the cross-sectional view of the armor desorption membrane (from the outside to the inside are the dense skin layer, the separation layer, and the porous layer);

[0051] Figure 2 It is a schematic diagram of the air chamber structure in the dry spinning stage;

[0052] Figure 3 It is a hollow fiber desorption membrane module, (a) is an external view, and (b) is a cross-sectional view. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0053] The following describes the present application in detail with reference to the embodiments, but the present application is not limited to these embodiments.

[0054] Unless otherwise specified, the raw materials in the embodiments of the present application are all purchased through commercial channels.

[0055] Unless otherwise specified, the test methods are all conventional methods, and the instrument settings are all the settings recommended by the manufacturer.

[0056] The applicant conducts research in the form of flat membranes, selects 6FDA-type copolyimide as the membrane material, and determines the optimal flat membrane preparation conditions by investigating the mechanical strength, solvent tolerance, membrane desorption CO2 permeation flux, and selectivity for methanol of the membrane. Using a flat membrane with a diameter of Φ300mm, through membrane desorption performance testing, this membrane has good CO2 flux and solvent resistance, and its CO2 mass transfer flux per unit space reaches ~45.0 kg / (m 3 ·h), and it has the feasibility to replace N2 stripping desorption of CO2.

[0057] According to an embodiment of the present application, the preparation process of the armor desorption membrane and its components is as follows:

[0058] (1) Preparation of the casting solution and the core liquid: Prepare the separation layer casting solution and the porous layer casting solution respectively. That is, according to the proportion requirements described in the claims, add the polymer membrane material, solvent, low-boiling additive (separation layer) / pore-forming agent (porous layer) into a stirrer, and set the temperature to the required value. Stir mechanically to form a homogeneous and transparent casting solution. The stirring time is generally not less than 12 hours, and the static defoaming time is generally not less than 12 hours; Prepare the core liquid as required, that is, mix the solvent and the non-solvent water in proportion and stir. Generally, the stirring time is not less than 2 hours, and after stirring, perform ultrasonic defoaming treatment;

[0059] (2) Hollow fiber membrane spinning: Introduce nitrogen into the separation layer casting solution tank and the porous layer casting solution tank respectively, with a pressure generally not less than 0.50 MPa. Introduce the two groups of casting solutions into the corresponding gear pumps respectively, and control the flow rate of the casting solution by setting the rotation speed of the gear pumps; Control the flow rate of the core liquid through a plunger pump; Introduce the two groups of casting solutions and the core liquid into a three-channel spinning nozzle respectively. The separation layer casting solution is introduced into the outermost layer, and the porous layer casting solution is introduced into the middle layer. The middle layer channel is shorter, and the two are mixed in the nozzle. The core liquid is introduced into the central hole to support the casting solution to form a nascent hollow fiber membrane; After the nascent hollow fiber membrane leaves the nozzle, it enters the Figure 2 shown air chamber. The N2 with controlled temperature and flow rate enters from the lower end of the air chamber and flows out from the upper end of the air chamber. This gas flow mode will form forced convection blowing on the surface of the nascent membrane, promoting the continuous volatilization of low-boiling components and part of the solvent in the casting solution to increase the polymer concentration on the outer surface of the membrane, which helps to form a dense skin layer on the surface of the separation layer and control its thickness; After the hollow fiber membrane leaves the air chamber, it enters the gel bath, and after contacting the non-solvent, solvent-non-solvent exchange occurs, and the precipitation of the solvent promotes the formation of a solidified membrane; After film formation, it enters the water washing tank, and the solvent in the membrane is further washed, and then the membrane filaments are collected on the winding wheel;

[0060] (3) Post-treatment of the hollow fiber membrane: Different from the porous membrane, the armor desorption membrane involved in the present invention has an outer dense skin layer and a relatively high polymer concentration in the casting solution. The membrane filaments also need to be post-treated to fully remove the solvent remaining therein, because the residual solvent will undergo a local re-dissolution process during the drying process of the membrane filaments, causing irreversible densification of the membrane filament structure. The post-treatment process generally places the membrane filaments in flowing tap water at a set temperature for sufficient cleaning, and the cleaning time is generally not less than 12 hours; the cleaned membrane filaments need to be dried at a high temperature to remove the contained moisture. The wet membrane filaments are placed in a forced-air drying oven, and the temperature is generally set at 105 °C, and the drying time is not less than 2 hours to obtain a dry hollow fiber membrane, that is, the armor desorption membrane;

[0061] (4) Preparation of the armor desorption membrane module: Place a certain number of armor desorption membranes in the membrane shell, and its filling rate is generally not less than 50%. Seal both ends with epoxy resin. After the epoxy resin cures, cut them separately so that the armor desorption membrane exposes the membrane pores, as Figure 3 shown, it can be applied to the CO2 membrane desorption and regeneration solvent process in the low-temperature methanol washing process.

[0062] Example 1 Preparation of the KJM armor desorption membrane and its module

[0063] (1) Preparation of the casting solution and the core liquid: The separation layer is 6FDA-type copolyimide / tetrahydrofuran / N-methylpyrrolidone, and the mass composition is 30% / 10% / 60%; the porous layer is polysulfone / polyethylene glycol / N-methylpyrrolidone, and the mass composition is 20% / 10% / 70%. After both membrane solutions are stirred at 80 °C for 24 hours, they are poured into the spinning tank, the temperature is controlled at 80 °C, and they are left standing for 24 hours for degassing and then spun.

[0064] (2) Spinning of the hollow fiber membrane: Introduce N2 with a pressure of 0.5 MPa into the two spinning tanks to drive the casting solution to flow towards the gear pump. Control the flow rates of the two casting solutions entering the three-channel spinning nozzle through the gear pump. The flow rate of the dense layer is 1.5 ml / min, the flow rate of the porous layer is 3.0 ml / min, the core liquid is a 50 wt% N-methylpyrrolidone aqueous solution, and the flow rate is 1.0 ml / min. The dry spinning distance is 15.0 cm, the N2 purge volume is 1.0 L / min, the purge temperature is the same as the spinning temperature, the gel bath is normal-temperature tap water, and the winding speed is 900 m / hr.

[0065] (3) Post-treatment of the hollow fiber membrane: After rinsing the prepared bottom membrane in flowing tap water for 48 hours, it was treated with ethanol (soaked for 3 hours) - n-hexane (soaked for 3 hours) solvent to remove the water contained in the membrane, and then placed in a forced-air oven for drying. The oven temperature was set at 105 °C to obtain an armor desorption membrane with a double-layer composite structure prepared from 6FDA-type copolyimide as the separation layer membrane material and polysulfone as the porous layer membrane material, labeled as the KJM armor desorption membrane.

[0066] (4) Preparation of the armor desorption membrane module: The prepared armor desorption membrane was loaded into the membrane tube at a filling rate of 45%, and both ends were sealed with epoxy resin. After curing, the epoxy on both sides was cut off to expose the inner hole of the armor membrane, obtaining the KJM armor desorption membrane module.

[0067] Preparation of Comparative Example 1 CGM Membrane and Its Module

[0068] (1) Prepare the casting solution, with the specific composition being 6FDA-type copolyimide / / N-methylpyrrolidone, and the mass composition being 28% / 72%; after stirring at 80 °C for 24 hours, it was poured into the spinning tank, the temperature was controlled at 80 °C, and left to stand for 24 hours for degassing before spinning. N2 with a pressure of 0.5 MPa was introduced into the spinning tank to drive the casting solution to flow towards the gear pump. The flow rate of the casting solution entering the two-channel nozzle was controlled by the gear pump to be 4.5 ml / min, and the core liquid was a 50 wt% aqueous solution of N-methylpyrrolidone with a flow rate of 1.0 ml / min. The dry spinning distance was 15.0 cm, the gel bath was normal-temperature tap water, and the wire drawing rate was 900 m / hr. After rinsing the prepared bottom membrane in flowing tap water for 48 hours, it was treated with ethanol (soaked for 3 hours) - n-hexane (soaked for 3 hours) solvent to remove the water contained in the membrane, and then placed in a forced-air oven for drying. The oven temperature was set at 105 °C to obtain the CGM membrane.

[0069] (2) The prepared CGM membrane was loaded into the membrane tube at a filling rate of 45%, and both ends were sealed with epoxy resin. After curing, the epoxy on both sides was cut off to expose the inner hole of the membrane, obtaining the CGM membrane module.

[0070] Test Example

[0071] Its gas permeability is shown in Table 1. The gas test method is as follows: At room temperature, a gas to be measured at a certain pressure is introduced into the shell layer of the membrane module, and it is fully replaced 3 - 5 times to ensure that the initial air is exhausted. Record the gas pressure in the shell layer at this time, and measure the flow rate of the gas that permeates through the membrane tube and flows out from both ends of the membrane module per unit time (in actual testing, one end needs to be sealed, and a soap bubble flowmeter can be used at the other end). By calculating the permeation volume of the gas per unit time, unit pressure, and unit area, the permeation rate of the gas in the membrane can be calculated. The commonly used unit is GPU, and 1.0 GPU = 1×10 -6cm 3 (STP) / (cm 2 s cmHg). The ratio of the permeation rates of the two gases is the separation coefficient of the membrane for the gas pair.

[0072] The CGM membrane is prepared by the conventional phase inversion method. The CO2 / N2 separation coefficient of its substrate membrane is about 1.6. After being coated with silicone rubber, the separation coefficient is increased to 25.0, which has reached the intrinsic separation coefficient of the membrane material. The CO2 flux of the membrane is about 60.0 GPU, that is, the thickness of the dense layer is about 0.40 μm. Since such a membrane has a silicone rubber coating, it cannot be in long-term contact with methanol liquid. After the silicone rubber layer is damaged, the desorption function of the membrane is lost. KJM is an armor desorption membrane directly prepared by optimizing and controlling the thermodynamic composition of the membrane solution and the spinning kinetics. Its CO2 / N2 separation coefficient has reached about 21.6, approaching the intrinsic separation coefficient of the membrane material; at the same time, its CO2 flux is about 10.8 GPU, that is, the thickness of the dense layer is about 2.40 μm. The results of the membrane desorption experiment prove that KJM has the performance of being in long-term contact with the methanol absorption liquid without being swollen and damaged, and its mass transfer flux per unit space is greatly increased to ~130.0 kg / (m 3 ·h).

[0073] Table 1 Comparison of Gas Permeation and Separation Performance between Conventional Membrane (CGM) and Armor Membrane (KJM) (0.50 MPa, 25.0 °C)

[0074]

[0075] The above are only examples of the present application and do not impose any form of limitation on the present application. Although the present application is disclosed above with preferred embodiments, it is not intended to limit the present application. Any person skilled in the art, without departing from the scope of the technical solution of the present application, makes some changes or modifications using the technical content disclosed above, which are equivalent to equivalent implementation cases and all fall within the scope of the technical solution.

Claims

1. An armor desorption membrane, characterized in that, The armor desorption membrane is a composite structure hollow fiber membrane; The composite structure hollow fiber membrane comprises, from outside to inside, a separation layer, a porous layer and a hollow cavity surrounded by the porous layer; The separation layer has an asymmetric structure, and the side of the separation layer facing away from the porous layer is a dense skin layer.

2. The armor desorption film according to claim 1, wherein The thickness of the dense layer in the separation layer is 1 to 3 μm; The thickness of the separation layer is 100 to 300 μm; The thickness of the porous layer is 100 to 300 μm; The materials of the separation layer and the porous layer are independently selected from at least one of polyimide, polyetherimide, cellulose, cellulose acetate, polysulfone, polyphenylsulfone, and polyvinylidene fluoride.

3. The preparation method of the armor desorption membrane according to claim 1 or 2, characterized in that, The steps include: S1, respectively preparing the separation layer casting liquid, the porous layer casting liquid and the core liquid; S2. A three-channel nozzle co-extrusion method is used to spin the separation layer casting liquid, the porous layer casting liquid and the core liquid to form a primary hollow fiber membrane, the primary membrane is purged through an air chamber, and then enters a gel bath to phase-transform into a membrane, thereby obtaining the armor desorption membrane.

4. The preparation method according to claim 3, characterized in that, The separation layer casting liquid includes a low boiling point component; The low boiling point component is selected from at least one of methanol, ethanol and tetrahydrofuran; Preferably, the casting solution of the porous layer includes a pore-forming agent; The pore-forming agent is selected from at least one of polyvinyl pyrrolidone, sodium chloride, potassium chloride, polyethylene glycol, and polyvinyl alcohol; Preferably, the core liquid comprises water and a solvent, wherein the concentration of the solvent is 0 to 90.0 wt %; Preferably, the concentration of the separation layer material in the separation layer casting solution is 30.0 to 45.0 wt %; Preferably, the concentration of the porous layer material in the casting solution of the porous layer is 15.0 to 30.0 wt %; Preferably, the solvent in the separation layer casting solution, the porous layer casting solution, and the core solution is independently selected from at least one of N-methylpyrrolidone, ethyl acetate, methyl ethylene glycol, ethylene glycol phenyl ether, and dimethylacetamide; Preferably, the concentration of the low boiling point component in the separation layer casting solution is 0 to 10.0 wt %; Preferably, the concentration of the pore-forming agent in the casting solution of the porous layer is 0 to 15.0 wt %.

5. The preparation method according to claim 3, characterized in that, During the spinning process, the temperatures of the separation layer casting solution, the porous layer casting solution and the core solution are independently controlled to be 20-100° C.; Preferably, the flow ratio of the separation layer casting solution to the porous layer casting solution is 0.1 to 10.0; Preferably, the flow ratio of the core liquid to the casting liquid of the porous layer is 0.1 to 10.0; Preferably, the spinning speed is 0 to 3000 m / hr.

6. The preparation method according to claim 3, characterized in that, The spinning process includes: the separation layer casting liquid, the porous layer casting liquid and the core liquid enter the outermost layer, the middle layer and the inner hole of the three-channel nozzle respectively, and the separation layer casting liquid contacts and fuses with the porous layer casting liquid in the nozzle, and leaves the nozzle in the form of a primary hollow fiber membrane.

7. The preparation method according to claim 3, characterized in that, The conditions for purging the primary membrane through the gas chamber include: the length of the purge space in the gas chamber is 0-50.0 cm, the purge gas is nitrogen, the temperature of the purge gas is 20.0-100.0° C., and the flow rate of the purge gas is 0-1000 ml / min.

8. The preparation method according to claim 3, characterized in that, The conditions for phase inversion film formation after entering the gel bath include: the gel bath is selected from water and / or ethanol, and the temperature of the gel bath is 0 to 100.0 °C; Preferably, the concentration of ethanol in the gel bath is 0 to 100.0 wt%.

9. The preparation method according to claim 3, characterized in that After phase inversion film formation after entering the gel bath, it further includes washing, wire winding, and drying.

10. Use of the armor desorption membrane according to claim 1 or 2 or the armor desorption membrane obtained by the preparation method according to any one of claims 3 to 9 for removing CO2 from the low-temperature methanol wash solvent; Preferably, the application includes placing the armor desorption membrane in bundles in a membrane shell, and preparing a desorption membrane assembly after sealing both ends with epoxy.

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