Tubular composite membrane for H2 / CO2 separation and preparation method

Abstract

The invention relates to a tubular composite membrane for H2 / CO2 separation and a preparation method thereof. Soaking the tubular support body in a water-phase solution containing 1, 2, 4, 5-phenylenetetramine tetrahydrochloride and 3, 3 '-diaminobenzidine tetrahydrochloride, enabling the water-phase solution to fully immerse the tubular support body, taking out the tubular support body from the water-phase solution, and naturally airing the tubular support body until no macroscopic liquid exists on the surface of the tubular support body; and soaking the support body in an organic phase solution containing terephthalaldehyde, carrying out interfacial polymerization reaction on the amino group and the aldehyde group at a two-phase interface, and generating the benzimidazole and imine connected polymer membrane on the surface of the support body. The membrane is used as a selective separation layer of the tubular composite membrane and has a mixed chain segment structure. And sequentially carrying out high-temperature heat treatment and polymer protection layer repair on the reacted membrane to obtain the final tubular composite membrane. When the temperature of feed gas is 150 DEG C and the pressure is 2 bar, the H2 permeability and the H2 / CO2 selectivity are 209 GPU and 22.5 respectively.

Description

Technical Field

[0001] This invention belongs to the technical field of gas separation membrane preparation technology and relates to a tubular composite membrane for H2 / CO2 separation and its preparation method. It also relates to a mixed-segment polymer membrane with good scalability, its preparation method by interfacial polymerization, and a method for repairing non-selective defects in the membrane. The membrane is suitable for separating H2 and CO2 gas systems at different temperatures (100-300°C) and pressures (2-19 bar). Background Art

[0002] Hydrogen is an important energy carrier and chemical raw material. While countries around the world are actively developing green hydrogen technologies, hydrogen production from fossil fuels still dominates the hydrogen production market due to its mature technology and low cost. During the fossil fuel hydrogen production process, fossil fuels react to produce shift gas primarily composed of H2 and CO2. High-purity hydrogen can be obtained through H2 / CO2 separation technology. H2 / CO2 separation technology is also used in biomass hydrogen production and hydrogen production from some by-product hydrogen. Therefore, the development of green and efficient H2 / CO2 separation technology is of great significance to hydrogen production and the achievement of the dual carbon goals.

[0003] Gas membrane separation technology offers advantages such as no phase transition and low energy consumption, promising ultra-high separation efficiencies. Furthermore, its compact footprint enhances its competitiveness for application on mobile platforms (ships, vehicles). The development of high-performance membrane materials and the scale-up of membrane production are key constraints on the application of H2 / CO2 separation membrane technology. In recent years, researchers have designed a variety of novel H2 / CO2 separation membrane materials, including metal-organic frameworks (MOFs), covalent organic frameworks (COFs), benzimidazole-imine-linked polymers (BIILPs), and benzimidazole-amide-linked polymers (BIALPs). The hydrogen bonding and π-π interactions within benzimidazoles endow these materials with powerful H2 and CO2 separation capabilities, resulting in their significant position in the field of H2 / CO2 separation membranes. Organic-inorganic composite membranes combine the excellent processability of polymers with the excellent stability of inorganic support layers, which provide mechanical strength to the polymer selective layer, thereby enhancing H2 / CO2 separation performance. Organic-inorganic composite tubular membranes are easily scalable, and scaling up membrane area is crucial for industrial applications. However, existing organic-inorganic composite tubular membranes have relatively low overall performance (low hydrogen permeability or selectivity less than 10), and H2 / CO2 separation performance urgently needs to be further improved.

[0004] Interfacial polymerization is widely used in the preparation of membranes (such as reverse osmosis membranes, nanofiltration membranes, and gas separation membranes). By manipulating the monomer type, the structure of the polymer separation layer can be flexibly adjusted, thereby improving membrane performance. Pinholes in the separation layer on the membrane surface create non-selective channels, which severely impair membrane performance in gas separation membranes. Therefore, repairing these non-selective channels on the membrane surface is essential for improving the performance of large-scale membranes. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for preparing a tubular composite membrane for efficient H2 / CO2 separation. Using interfacial polymerization, the structure of the polybenzimidazole and imine-linked polymer separation layer is optimized by combining aqueous solution monomers with different diffusion properties (1,2,4,5-benzenetetramine tetrahydrochloride and 3,3'-diaminobenzidine tetrahydrochloride). A mixed-segment polymer separation layer with high H2 / CO2 separation performance is prepared on a tubular support. Furthermore, a polymer that enables preferential H2 permeation is coated on the separation layer to repair non-selective defects, resulting in a membrane capable of separating H2 and CO2 at different temperatures (100-300°C) and pressures (2-19 bar). The membrane has a single membrane area of ​​37.7 cm2. 2 The polymer separation layer contains several structural units as shown below. By combining multiple structural units, a polymer separation layer with a mixed segment structure is constructed, which significantly improves the gas separation performance of the membrane.

[0006]

[0007] The technical solutions proposed by the present invention to achieve the above-mentioned purpose are as follows:

[0008] The present invention discloses a tubular composite membrane for H2 / CO2 separation, comprising a support layer, a separation layer and a protective layer; wherein the support layer is a tubular inorganic support, the separation layer is a mixed segment polymer containing benzimidazole linkages, and the protective layer is polyimide.

[0009] The tubular composite membrane for H2 / CO2 separation has a separation layer containing two or more polymer segments, and a thickness of the separation layer of 20-500 nm.

[0010] A method for preparing a tubular composite membrane for H2 / CO2 separation according to the present invention comprises the following steps:

[0011] 1) Soaking the tubular support in an aqueous solution containing 1,2,4,5-phenylenetetramine tetrahydrochloride and 3,3'-diaminobenzidine tetrahydrochloride, allowing the aqueous solution to fully penetrate the tubular support. The tubular support is removed from the solution and allowed to dry naturally until no liquid is visible on the surface of the support.

[0012] 2) immersing the support obtained in step 1) in an organic phase solution of terephthalaldehyde, wherein the amino monomer reacts with the aldehyde monomer in the organic phase solution to form a mixed segment polymer film on the surface of the support;

[0013] 3) Place the tubular membrane obtained in step 2) into a preheated oven, take it out after heat treatment, and naturally cool it to room temperature;

[0014] 4) Using a film-pulling coating machine, a layer of polyimide is coated on the outer surface of the tubular membrane obtained in step 3) to obtain a tubular composite membrane.

[0015] In step 1) of the method for preparing the tubular composite membrane, the support is a tubular inorganic support.

[0016] In the preparation method of the tubular composite membrane, the aqueous solution in step 1) contains 1,2,4,5-benzenetetramine tetrahydrochloride and 3,3'-diaminobenzidine tetrahydrochloride, with mass concentrations of 0.5wt%-2wt% respectively, and the immersion time is 1-60 minutes.

[0017] In step 2) of the preparation method of the tubular composite membrane, the solute of the organic phase solution is terephthalaldehyde, the solvent is toluene, the reaction time is 1-120 minutes, and the mass concentration of terephthalaldehyde is 0.5wt%-2wt%.

[0018] In step 2) of the method for preparing the tubular composite membrane, the amino monomer in the aqueous solution and the aldehyde monomer in the organic solution undergo interfacial polymerization to form a mixed segment polymer membrane on the outer surface of the tubular support.

[0019] In the preparation method of the tubular composite membrane, the tubular membrane obtained by the interfacial polymerization reaction in step 3) needs to be placed in a preheated oven at 100-250° C. for high-temperature heat treatment for 1-48 hours.

[0020] The preparation method of the tubular composite membrane comprises the following steps: Step 4) the coating method is a pulling method, the pulling speed is 20-500 μm / s, the solute of the polymer solution used for the coating is soluble polyimide, the solvent is dichloromethane, and the mass concentration of the polyimide is in the range of 0.1-5wt%.

[0021] The tubular composite membrane of the present invention is used for separation of H2 / CO2 mixed gas at different temperatures and pressures.

[0022] The method for preparing a tubular H2 / CO2 separation membrane disclosed in the present invention is different from traditional H2 / CO2 separation membranes. It uses a ceramic tubular support with good stability and easy scalability to prepare an organic-inorganic tubular composite membrane for efficient H2 / CO2 separation. Inorganic supports have advantages such as good thermal stability and strong rigidity, and are suitable for the separation of conversion gas systems with high temperature and high pressure characteristics. Therefore, inorganic supports are widely used in the preparation of H2 / CO2 separation membranes. However, inorganic supports also have the disadvantage of being difficult to scale up, especially flat inorganic supports. Tubular inorganic supports have the advantage of being easy to scale up and have been applied in fields such as water treatment and permeation gasification. The present invention utilizes a simple interfacial polymerization method to specifically design water and oil phase monomers for the special interfacial polymerization environment on the surface of the tubular membrane. By using two water phase monomers with different diffusion characteristics, a polymer separation layer with a mixed chain segment structure is prepared, which effectively improves the selectivity of the membrane. In addition, the membrane obtained by interfacial polymerization is treated with high-temperature heat treatment. Due to the volatilization of oligomers and the movement of polymer chains, the hydrogen selective channels in the membrane increase. The use of high-temperature resistant polyimide, which allows H2 to preferentially permeate, to repair the non-selective defects in the separation layer significantly improves the gas separation performance of the tubular composite membrane. Figure 2 As shown, the membrane can withstand a feed pressure of 2-19 bar.

[0023] Compared with the prior art, the advantages of the present invention are as follows:

[0024] The present invention uses commercially used Al2O3 ceramic tubes as the supporting layer material, and the prepared tubular composite membrane has a single membrane area of ​​37.7 cm 2 , and is easy to scale up and prepare. In addition, the present invention optimizes the membrane structure and membrane performance through a mixed monomer strategy from the perspective of the diffusion characteristics of aqueous phase monomers. The method is simple and effective. Finally, the present invention addresses the problem that the non-selective channels in the separation layer of large-area membranes seriously damage the membrane performance, screens out suitable protective layer materials and coating processes, and significantly improves the membrane performance. Figure 3 As shown in FIG, there is no significant difference in the performance of 20 tubular membranes prepared under the same conditions, which proves that the present invention has a good reproducibility. Figure 4 As shown, membrane performance did not significantly change when using a new support, a support that had been recycled once, or a support that had been recycled twice. Given the high temperature and pressure characteristics of shift gas and the industry's demand for high-purity hydrogen, the membrane's temperature and pressure resistance, as well as its performance without a purge gas, were tested.

[0025] Under the conditions of feed gas temperature of 100℃, pressure of 2 bar and Ar as permeate side purge gas, the average H2 permeance and H2 / CO2 selectivity are 91.2GPU and 27.1, respectively.

[0026] Under the conditions of feed gas temperature of 150℃, pressure of 2 bar and Ar as permeate side purge gas, the average H2 permeance and H2 / CO2 selectivity are 209GPU and 22.5, respectively.

[0027] Under the conditions of feed gas temperature of 150℃, pressure of 10 bar and Ar as permeate side purge gas, the H2 permeance and H2 / CO2 selectivity are 140GPU and 17.3 respectively.

[0028] Under the conditions of feed gas temperature of 150℃, pressure of 19 bar and Ar as permeate side purge gas, the H2 permeance and H2 / CO2 selectivity were 84.9GPU and 8.09, respectively.

[0029] Under the conditions of feed gas temperature of 200℃, pressure of 10 bar and Ar as permeate side purge gas, the average H2 permeance and H2 / CO2 selectivity are 212GPU and 11.1, respectively.

[0030] Under the conditions of feed gas temperature of 200℃, pressure of 2 bar and Ar as permeate side purge gas, the H2 permeance and H2 / CO2 selectivity are 322GPU and 13.2, respectively.

[0031] Under the conditions of feed gas temperature of 200℃, pressure of 10 bar and no purge gas, the H2 permeance and H2 / CO2 selectivity were 189GPU and 10.4, respectively.

[0032] The test results above demonstrate the advantages of the tubular membrane produced using this invention: the mixed-segment polymer separation layer improves the membrane's gas separation performance, and the protective layer repairs some of the membrane's non-selective defects. The membrane's selectivity at a relatively low pressure (2 bar) is significantly higher than that of currently available tubular organic-inorganic composite membranes. Furthermore, even at elevated test pressures (10 and 19 bar) based on industrial use scenarios and without the use of a purge gas, the membrane still effectively separates hydrogen and carbon dioxide. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a schematic diagram of the preparation method of the present invention and a schematic diagram of the mixed chain segment polymer molecular fragment.

[0034] Figure 2 The gas separation performance of the tubular composite membrane M200-PI-2 under different feed gas pressures when the feed gas temperature is 150°C in Example 1 of the present invention.

[0035] Figure 3 The gas separation performance of the 20-branched tubular composite membrane prepared according to the method described in Example 1 of the present invention when the feed gas temperature is 100° C. and the pressure is 2 bar.

[0036] Figure 4 The gas separation performance of tubular composite membranes prepared using new supports and used supports recycled once or twice according to the method described in Example 1 of the present invention is shown in FIG. Feed gas temperature: 150° C., feed gas pressure: 2 bar.

[0037] Figure 5 This is a SEM image of the surface of a tubular composite membrane prepared according to the method described in Example 1 of the present invention.

[0038] Figure 6 This is a cross-sectional SEM image of a tubular composite membrane prepared according to the method described in Example 1 of the present invention.

[0039] Figure 7 This is a surface infrared spectrum of the tubular composite membrane prepared according to the method described in Example 1 of the present invention.

[0040] Figure 8 This is a cross-sectional SEM image of a tubular composite membrane prepared according to the method described in Example 9 of the present invention. DETAILED DESCRIPTION

[0041] The present invention is further described below with reference to the accompanying drawings and specific examples. All chemicals and reagents used in the examples are commercially available unless otherwise specified.

[0042] Tubular composite membrane gas separation performance test method: The WK method is used to detect the composition and concentration of the permeate side gas through a gas chromatograph, and then the membrane performance is calculated.

[0043] Gas membrane separation performance calculation formula:

[0044] The permeability of component i (P i ) is calculated as follows:

[0045]

[0046] Where N i is the permeation rate of component i (mol·s -1 ); A is the effective membrane area of ​​the tubular membrane (m 2 );Δp i is the partial pressure difference (Pa) of component i on both sides of the membrane. GPU is used as P i Unit, 1GPU = 3.35×10 -10 mol·m -2 ·Pa -1 ·s -1 .

[0047] The H2 / CO2 selectivity (α) is calculated as follows:

[0048]

[0049] Preparation method Figure 1 The specific instructions are as follows:

[0050] A method for preparing a tubular composite membrane for H2 / CO2 separation comprises the following steps:

[0051] 1) Immersing the tubular support in an aqueous solution containing 1,2,4,5-phenylenetetramine tetrahydrochloride and 3,3'-diaminobenzidine tetrahydrochloride hydrate, allowing the aqueous solution to fully penetrate the support. After 1-60 minutes, the tubular support is removed from the aqueous solution and allowed to air dry naturally until no liquid is visible on the surface of the support.

[0052] 2) The support obtained in step 1) is immersed in an organic phase solution containing terephthalaldehyde, and the monomers 1,2,4,5-benzenetetramine tetrahydrochloride and 3,3'-diaminobenzidine tetrahydrochloride in the aqueous phase solution and the monomer terephthalaldehyde in the organic phase solution undergo a polymerization reaction at the interface between the two phases to form a continuous benzimidazole-linked polymer film on the surface of the support, the reaction time is 1-120 minutes, and the film has a mixed segment structure;

[0053] 3) Place the tubular membrane prepared in step 2) in a preheated oven at 100-250°C, and cool naturally to room temperature after heat treatment;

[0054] 4): One end of the heat-treated tubular membrane obtained in step 3) is sealed and fixed on the working module of the pulling coating machine (the closed end is at the bottom). After immersing the tubular membrane in a homogeneous solution containing a soluble polyimide, the tubular membrane is pulled upward at 20-500 μm / s to coat the outer surface of the tubular membrane with a polyimide protective layer to obtain a tubular composite membrane having a three-layer structure of a support layer, a separation layer, and a protective layer.

[0055] The support in step 1) is an Al2O3 ceramic tube.

[0056] The mass percentage concentration of each monomer in the aqueous solution of step 1) is 0.5-2 wt %, preferably 0.8-1.2 wt %.

[0057] The solvent of the organic phase in step 2) is toluene, and the mass percentage concentration of terephthalaldehyde in toluene is 0.5-2 wt %, preferably 0.6-1 wt %.

[0058] In the step 2), the aqueous phase monomer and the organic phase monomer undergo interfacial polymerization reaction, and the reaction time is preferably 1-120 min, preferably 10-20 min.

[0059] The tubular membrane prepared in step 3) is placed in a preheated oven at 100-250° C. for heat treatment. The heat treatment temperature is preferably 150-200° C., and the heat treatment time is 1-48 hours, preferably 24 hours.

[0060] The solvent of the polyimide solution in step 4) is dichloromethane, the solute is soluble polyimide, and the mass percentage concentration is preferably 0.1-5 wt %.

[0061] Example 1

[0062] 1) At room temperature, 0.3 g each of 1,2,4,5-phenyltetramine tetrahydrochloride (BTA) and 3,3'-diaminobenzidine tetrahydrochloride hydrate (DAB) were weighed into a beaker. 29.4 g of deionized water was added to the beaker, and the beaker was placed in an ultrasonicator to promote solute dissolution, resulting in a total mass of 30 g of an aqueous solution with a BTA and DAB mass percentage concentration of 1 wt %.

[0063] 2) At room temperature, 0.24 g of terephthalaldehyde (TPA) was weighed into a beaker, 29.76 g of toluene was added to the beaker, and the beaker was placed in an ultrasonic machine to promote solute dissolution, to obtain an organic phase solution with a total mass of 30 g and a TPA mass percentage concentration of 0.8 wt%.

[0064] 3) 2.0 g of soluble polyimide was weighed into a beaker at room temperature, 198 g of dichloromethane and a magnetic stirrer were added to the beaker, the beaker was placed on a magnetic stirrer, and magnetic stirring was turned on to promote the dissolution of the polyimide to obtain a polyimide solution with a total mass of 200 g and a polyimide mass percentage concentration of 1.0 wt%.

[0065] 4) Immerse the tubular support in the prepared aqueous solution. After 15 minutes, remove the support and place it on a table to dry naturally until no visible solution is left on the surface. Immediately place the support in the organic solution. The organic solution is left at room temperature for 15 minutes. During this time, interfacial polymerization occurs between the amino monomer and the aldehyde monomer, forming a brown film on the outer surface of the tubular support.

[0066] 5) The prepared tubular membrane was placed in a preheated constant temperature forced air drying oven for heat treatment at 200° C. for 24 h.

[0067] 6) Applying a polymer protective layer to the membrane surface to repair non-selective defects: Remove the tubular membrane from the oven, allow it to cool to room temperature, seal one end with polytetrafluoroethylene film, and then secure it to the working module of a servo micron pull-up coating machine (with the sealed end facing downward). The pull-up machine is controlled to completely immerse the tubular membrane in the polyimide solution. Then, at a pulling speed of 80 μm / s, the membrane is pulled out of the polyimide solution, forming a polyimide coating on the outer surface of the tubular membrane.

[0068] 7) The prepared tubular composite membrane was placed in a fume hood and dried for 1 day to allow the residual solvent in the membrane to evaporate naturally. This membrane was labeled M200-PI-2. The gas separation performance of the membrane was tested using a gas separation performance tester: under the conditions of a feed gas temperature of 150°C and a pressure of 2 bar, the membrane's H2 permeability and H2 / CO2 selectivity were 195 GPU and 28.2, respectively; under the conditions of a feed gas temperature of 150°C and a pressure of 10 bar, the membrane's H2 permeability and H2 / CO2 selectivity were 140 GPU and 17.3, respectively; under the conditions of a feed gas temperature of 150°C and a pressure of 15 bar, the membrane's H2 permeability and H2 / CO2 selectivity were 99.4 GPU and 10.4, respectively; and under the conditions of a feed gas temperature of 150°C and a pressure of 19 bar, the membrane's H2 permeability and H2 / CO2 selectivity were 84.9 GPU and 8.09, respectively. The membrane prepared in this embodiment can still achieve effective separation of H2 and CO2 under elevated pressure conditions, and its pressure resistance performance is in a leading position among membranes with the same membrane area.

[0069] Example 2

[0070] 1) At room temperature, 0.3 g each of 1,2,4,5-phenyltetramine tetrahydrochloride (BTA) and 3,3'-diaminobenzidine tetrahydrochloride hydrate (DAB) were weighed into a beaker. 29.4 g of deionized water was added to the beaker, and the beaker was placed in an ultrasonicator to promote solute dissolution, resulting in a total mass of 30 g of an aqueous solution with a BTA and DAB mass percentage concentration of 1 wt %.

[0071] 2) At room temperature, 0.24 g of terephthalaldehyde (TPA) was weighed into a beaker, 29.76 g of toluene was added to the beaker, and the beaker was placed in an ultrasonic machine to promote solute dissolution, to obtain an organic phase solution with a total mass of 30 g and a TPA mass percentage concentration of 0.8 wt%.

[0072] 3) 2.0 g of soluble polyimide was weighed into a beaker at room temperature, 198 g of dichloromethane and a magnetic stirrer were added to the beaker, the beaker was placed on a magnetic stirrer, and magnetic stirring was turned on to promote the dissolution of the polyimide to obtain a polyimide solution with a total mass of 200 g and a polyimide mass percentage concentration of 1.0 wt%.

[0073] 4) Immerse the tubular support in the prepared aqueous solution. After 15 minutes, remove the support and place it on a table to dry naturally until no visible solution is left on the surface. Immediately place the support in the organic solution. The organic solution is left at room temperature for 15 minutes. During this time, interfacial polymerization occurs between the amino monomer and the aldehyde monomer, forming a brown film on the outer surface of the tubular support.

[0074] 5) The prepared tubular membrane was placed in a preheated constant temperature forced air drying oven for heat treatment at 200° C. for 24 h.

[0075] 6) Applying a polymer protective layer to the membrane surface to repair non-selective defects: Remove the tubular membrane from the oven, allow it to cool to room temperature, seal one end with polytetrafluoroethylene film, and then secure it to the working module of a servo micron pull-up coating machine (with the sealed end facing downward). The pull-up machine is controlled to completely immerse the tubular membrane in the polyimide solution. Then, at a pulling speed of 80 μm / s, the membrane is pulled out of the polyimide solution, forming a polyimide coating on the outer surface of the tubular membrane.

[0076] 7) The prepared tubular composite membrane was placed in a fume hood and dried for 1 day to allow the remaining solvent in the membrane to evaporate naturally. The membrane was labeled M200-PI-1. Under the conditions of a feed gas temperature of 200°C and a pressure of 10 bar, the gas separation performance of the membrane was tested using a gas separation performance test device. The H2 permeability and H2 / CO2 selectivity of the membrane were 211GPU and 12, respectively. Under the conditions of a feed gas temperature of 200°C and a pressure of 10 bar, the purge gas on the permeate side of the membrane was turned off, and the H2 permeability and H2 / CO2 selectivity of the membrane were 189GPU and 10.4, respectively. The above results show that when the feed gas pressure is 10 bar, the elimination of the purge gas has no significant effect on the membrane performance, meeting the industrial need for no purge gas.

[0077] Example 3

[0078] 1) At room temperature, 0.15 g each of 1,2,4,5-phenyltetramine tetrahydrochloride (BTA) and 3,3'-diaminobenzidine tetrahydrochloride hydrate (DAB) were weighed into a beaker. 29.7 g of deionized water was added to the beaker, and the beaker was placed in an ultrasonicator to promote solute dissolution, resulting in a total mass of 30 g of an aqueous solution with a BTA and DAB mass percentage concentration of 0.5 wt %.

[0079] 2) At room temperature, 0.6 g of each of 1,2,4,5-benzenetetramine tetrahydrochloride (BTA) and 3,3'-diaminobenzidine tetrahydrochloride hydrate (DAB) were weighed into a beaker. 28.8 g of deionized water was added to the beaker. The beaker was placed in an ultrasonic machine to promote the dissolution of the solutes, resulting in a total mass of 30 g of an aqueous solution with a BTA and DAB mass percentage concentration of 2 wt% respectively.

[0080] 3) At room temperature, 0.96 g of terephthalaldehyde (TPA) was weighed into a beaker, 119.04 g of toluene was added to the beaker, and the beaker was placed in an ultrasonic machine to promote solute dissolution, resulting in an organic phase solution with a total mass of 120 g and a TPA mass percentage concentration of 0.8 wt%.

[0081] 4) Weigh 2.0 g of soluble polyimide into a beaker at room temperature, add 198 g of dichloromethane and a magnetic stirrer to the beaker, place the beaker on a magnetic stirrer, and turn on the magnetic stirring to promote the dissolution of the polyimide to obtain a polyimide solution with a total mass of 200 g and a polyimide mass percentage concentration of 1.0 wt %.

[0082] 5) Immerse the tubular support in the prepared aqueous solution. After 15 minutes, remove the support and place it on a table to dry naturally until no solution is visible on the surface. Immediately place the support in the organic solution. The organic solution is left at room temperature for 15 minutes. During this time, interfacial polymerization occurs between the amino monomer and the aldehyde monomer, forming a brown film on the outer surface of the tubular support.

[0083] 6) The prepared tubular membrane was placed in a preheated constant temperature forced air drying oven for heat treatment at 200° C. for 24 h.

[0084] 7) Applying a polymer protective layer to the membrane surface to repair non-selective defects: Remove the tubular membrane from the oven, allow it to cool to room temperature, seal one end with polytetrafluoroethylene film, and then secure it to the working module of a servo micron pull-up coating machine (with the sealed end facing downward). The pull-up machine is controlled to completely immerse the tubular membrane in the polyimide solution. Then, at a pulling speed of 80 μm / s, the membrane is pulled out of the polyimide solution, forming a polyimide coating on the outer surface of the tubular membrane.

[0085] 8) The prepared tubular composite membrane was placed in a fume hood and dried for 1 day to allow the remaining solvent in the membrane to evaporate naturally. The gas separation performance of the membrane was tested using a gas separation performance tester under feed gas conditions of 150°C and 2 bar. The results are shown in Table 1.

[0086] Table 1 Monomer concentration in aqueous solution and its effect on membrane performance

[0087]

[0088] Note: The feed gas temperature and pressure are 150°C and 2 bar respectively.

[0089] Example 4

[0090] 1) At room temperature, 0.3 g each of 1,2,4,5-phenyltetramine tetrahydrochloride (BTA) and 3,3'-diaminobenzidine tetrahydrochloride hydrate (DAB) were weighed into a beaker. 29.4 g of deionized water was added to the beaker, and the beaker was placed in an ultrasonicator to promote solute dissolution, resulting in a total mass of 30 g of an aqueous solution with a BTA and DAB mass percentage concentration of 1 wt %.

[0091] 2) At room temperature, 0.15 g of terephthalaldehyde (TPA) was weighed into a beaker, 29.85 g of toluene was added to the beaker, and the beaker was placed in an ultrasonic machine to promote solute dissolution, to obtain an organic phase solution with a total mass of 30 g and a TPA mass percentage concentration of 0.5 wt%.

[0092] 3) At room temperature, 0.6 g of terephthalaldehyde (TPA) was weighed into a beaker, 29.4 g of toluene was added to the beaker, and the beaker was placed in an ultrasonic machine to promote solute dissolution, to obtain an organic phase solution with a total mass of 30 g and a TPA mass percentage concentration of 2 wt%.

[0093] 4) Weigh 2.0 g of soluble polyimide into a beaker at room temperature, add 198 g of dichloromethane and a magnetic stirrer to the beaker, place the beaker on a magnetic stirrer, and turn on the magnetic stirring to promote the dissolution of the polyimide to obtain a polyimide solution with a total mass of 200 g and a polyimide mass percentage concentration of 1.0 wt %.

[0094] 5) Immerse the tubular support in the prepared aqueous solution. After 15 minutes, remove the support and place it on a table to dry naturally until no solution is visible on the surface. Immediately place the support in the organic solution. The organic solution is left at room temperature for 15 minutes. During this time, interfacial polymerization occurs between the amino monomer and the aldehyde monomer, forming a brown film on the outer surface of the tubular support.

[0095] 6) The prepared tubular membrane was placed in a preheated constant temperature forced air drying oven, the temperature was set to 200° C., and the heat treatment time was 24 h.

[0096] 7) Applying a polymer protective layer to the membrane surface to repair non-selective defects: Remove the tubular membrane from the oven, allow it to cool to room temperature, seal one end with polytetrafluoroethylene film, and then secure it to the working module of a servo micron pull-up coating machine (with the sealed end facing downward). The pull-up machine is controlled to completely immerse the tubular membrane in the polyimide solution. Then, at a pulling speed of 80 μm / s, the membrane is pulled out of the polyimide solution, forming a polyimide coating on the outer surface of the tubular membrane.

[0097] 8) The prepared tubular composite membrane was dried in a fume hood for 1 day to allow the remaining solvent in the membrane to evaporate naturally. The membrane's gas separation performance was tested using a gas separation performance tester at a feed gas temperature of 150°C and a pressure of 2 bar. When the TPA concentration was 0.5 wt%, the membrane's H2 permeability and H2 / CO2 selectivity were 215 GPU and 18.9, respectively. When the TPA concentration was 2 wt%, the membrane's H2 permeability and H2 / CO2 selectivity were 112 GPU and 19.6, respectively.

[0098] Example 5

[0099] 1) At room temperature, 0.3 g each of 1,2,4,5-phenyltetramine tetrahydrochloride (BTA) and 3,3'-diaminobenzidine tetrahydrochloride hydrate (DAB) were weighed into a beaker. 29.4 g of deionized water was added to the beaker, and the beaker was placed in an ultrasonicator to promote solute dissolution, resulting in a total mass of 30 g of an aqueous solution with a BTA and DAB mass percentage concentration of 1 wt %.

[0100] 2) At room temperature, 0.24 g of terephthalaldehyde (TPA) was weighed into a beaker, 29.76 g of toluene was added to the beaker, and the beaker was placed in an ultrasonic machine to promote solute dissolution, to obtain an organic phase solution with a total mass of 30 g and a TPA mass percentage concentration of 0.8 wt%.

[0101] 3) 2.0 g of soluble polyimide was weighed into a beaker at room temperature, 198 g of dichloromethane and a magnetic stirrer were added to the beaker, the beaker was placed on a magnetic stirrer, and magnetic stirring was turned on to promote the dissolution of the polyimide to obtain a polyimide solution with a total mass of 200 g and a polyimide mass percentage concentration of 1.0 wt%.

[0102] 4) Immerse the tubular support in the prepared aqueous solution. After 15 minutes, remove the support and allow it to dry naturally on a tabletop until no visible solution remains on the surface. Immediately place the support in the organic solution. The organic solution is kept at room temperature. The reaction times are set at 1 minute and 120 minutes, respectively. During this time, interfacial polymerization of the amino and aldehyde monomers occurs, forming a brown film on the outer surface of the tubular support.

[0103] 5) The prepared tubular membrane was placed in a preheated constant temperature forced air drying oven, the temperature was set to 200° C., and the heat treatment time was 24 h.

[0104] 6) Applying a polymer protective layer to the membrane surface to repair non-selective defects: Remove the tubular membrane from the oven, allow it to cool to room temperature, seal one end with polytetrafluoroethylene film, and then secure it to the working module of a servo micron pull-up coating machine (with the sealed end facing downward). The pull-up machine is controlled to completely immerse the tubular membrane in the polyimide solution. Then, at a pulling speed of 80 μm / s, the membrane is pulled out of the polyimide solution, forming a polyimide coating on the outer surface of the tubular membrane.

[0105] 7) The prepared tubular composite membrane was dried in a fume hood for 1 day to allow the remaining solvent in the membrane to evaporate naturally. The membrane's gas separation performance was tested using a gas separation performance tester at a feed gas temperature of 150°C and a pressure of 2 bar. When the reaction time was 1 minute, the membrane's H2 permeability and H2 / CO2 selectivity were 256 GPU and 16.4, respectively. When the reaction time was 120 minutes, the membrane's H2 permeability and H2 / CO2 selectivity were 105 GPU and 21.1, respectively.

[0106] Example 6

[0107] 1) At room temperature, 0.3 g each of 1,2,4,5-phenyltetramine tetrahydrochloride (BTA) and 3,3'-diaminobenzidine tetrahydrochloride hydrate (DAB) were weighed into a beaker. 29.4 g of deionized water was added to the beaker, and the beaker was placed in an ultrasonicator to promote solute dissolution, resulting in a total mass of 30 g of an aqueous solution with a BTA and DAB mass percentage concentration of 1 wt %.

[0108] 2) At room temperature, 0.24 g of terephthalaldehyde (TPA) was weighed into a beaker, 29.76 g of toluene was added to the beaker, and the beaker was placed in an ultrasonic machine to promote solute dissolution, to obtain an organic phase solution with a total mass of 30 g and a TPA mass percentage concentration of 0.8 wt%.

[0109] 3) 2.0 g of soluble polyimide was weighed into a beaker at room temperature, 198 g of dichloromethane and a magnetic stirrer were added to the beaker, the beaker was placed on a magnetic stirrer, and magnetic stirring was turned on to promote the dissolution of the polyimide to obtain a polyimide solution with a total mass of 200 g and a polyimide mass percentage concentration of 1.0 wt%.

[0110] 4) Immerse the tubular support in the prepared aqueous solution. After 15 minutes, remove the support and allow it to dry naturally on a tabletop until no visible solution remains on the surface. Immediately place the support in the organic solution. The organic solution is left at room temperature for 15 minutes. During this time, interfacial polymerization of the amino and aldehyde monomers occurs, forming a brown film on the outer surface of the tubular support.

[0111] 5) Under these conditions, two tubular membranes were prepared and placed in two preheated constant temperature blast drying ovens for heat treatment at 100°C and 250°C for 24 hours.

[0112] 6) Applying a polymer protective layer to the membrane surface to repair non-selective defects: Remove the tubular membrane from the oven, allow it to cool to room temperature, seal one end with polytetrafluoroethylene film, and then secure it to the working module of a servo micron pull-up coating machine (with the sealed end facing downward). The pull-up machine is controlled to completely immerse the tubular membrane in the polyimide solution. Then, at a pulling speed of 80 μm / s, the membrane is pulled out of the polyimide solution, forming a polyimide coating on the outer surface of the tubular membrane.

[0113] 7) The prepared tubular composite membrane was dried in a fume hood for 1 day to allow the remaining solvent in the membrane to evaporate naturally. The membrane's gas separation performance was tested using a gas separation performance tester at a feed gas temperature of 150°C and a pressure of 2 bar. When the heat treatment temperature was 100°C, the membrane's H2 permeability and H2 / CO2 selectivity were 89 GPU and 22.1, respectively. When the reaction time was 250°C, the membrane's H2 permeability and H2 / CO2 selectivity were 261 GPU and 17.2, respectively.

[0114] Example 7

[0115] 1) At room temperature, 0.3 g each of 1,2,4,5-phenyltetramine tetrahydrochloride (BTA) and 3,3'-diaminobenzidine tetrahydrochloride hydrate (DAB) were weighed into a beaker. 29.4 g of deionized water was added to the beaker, and the beaker was placed in an ultrasonicator to promote solute dissolution, resulting in a total mass of 30 g of an aqueous solution with a BTA and DAB mass percentage concentration of 1 wt %.

[0116] 2) At room temperature, 0.24 g of terephthalaldehyde (TPA) was weighed into a beaker, 29.76 g of toluene was added to the beaker, and the beaker was placed in an ultrasonic machine to promote solute dissolution, to obtain an organic phase solution with a total mass of 30 g and a TPA mass percentage concentration of 0.8 wt%.

[0117] 3) Weigh 0.2 g of a soluble polyimide into a beaker at room temperature, add 199.8 g of dichloromethane and a magnetic stir bar to the beaker, place the beaker on a magnetic stirrer, and start magnetic stirring to promote dissolution of the polyimide, to obtain a polyimide solution with a total mass of 200 g and a polyimide mass percentage concentration of 0.1 wt %. Weigh 10 g of a soluble polyimide into a beaker at room temperature, add 190 g of dichloromethane and a magnetic stir bar to the beaker, place the beaker on a magnetic stirrer, and start magnetic stirring to promote dissolution of the polyimide, to obtain a polyimide solution with a total mass of 200 g and a polyimide mass percentage concentration of 5 wt %.

[0118] 4) Immerse the tubular support in the prepared aqueous solution. After 15 minutes, remove the support and allow it to dry naturally on a tabletop until no visible solution remains on the surface. Immediately place the support in the organic solution. The organic solution is left at room temperature for 15 minutes. During this time, interfacial polymerization of the amino and aldehyde monomers occurs, forming a brown film on the outer surface of the tubular support.

[0119] 5) Under these conditions, two tubular membranes were prepared and placed in a preheated constant temperature forced air drying oven for heat treatment at 200°C for 24 hours.

[0120] 6) Coating a polymer protective layer on the membrane surface to repair non-selective defects: Remove the tubular membrane from the oven, wait for the membrane to cool to room temperature, seal one end of the membrane with a polytetrafluoroethylene membrane, and then fix it to the working module of the servo micron pulling coating machine (with the closed end at the bottom). Control the pulling machine working module so that the tubular membrane is completely immersed in the polyimide solution. The concentrations of the polyimide solutions coated on the two membranes are 0.1wt% and 5wt%, respectively. Subsequently, set the pulling speed to 80μm / s and pull the membrane out of the polyimide solution. At this time, a polyimide coating will form on the outer surface of the tubular membrane.

[0121] 7) The prepared tubular composite membrane was dried in a fume hood for 1 day to allow the remaining solvent in the membrane to evaporate naturally. The membrane's gas separation performance was tested using a gas separation performance tester at a feed gas temperature of 150°C and a pressure of 2 bar. When the coating polyimide solution concentration was 0.1 wt%, the membrane exhibited an H2 permeability and H2 / CO2 selectivity of 295 GPU and 14.7, respectively. When the coating polyimide solution concentration was 5 wt%, the membrane exhibited an H2 permeability and H2 / CO2 selectivity of 89 GPU and 32.6, respectively.

[0122] Example 8

[0123] 1) At room temperature, 0.3 g each of 1,2,4,5-phenyltetramine tetrahydrochloride (BTA) and 3,3'-diaminobenzidine tetrahydrochloride hydrate (DAB) were weighed into a beaker. 29.4 g of deionized water was added to the beaker, and the beaker was placed in an ultrasonicator to promote solute dissolution, resulting in a total mass of 30 g of an aqueous solution with a BTA and DAB mass percentage concentration of 1 wt %.

[0124] 2) At room temperature, 0.24 g of terephthalaldehyde (TPA) was weighed into a beaker, 29.76 g of toluene was added to the beaker, and the beaker was placed in an ultrasonic machine to promote solute dissolution, to obtain an organic phase solution with a total mass of 30 g and a TPA mass percentage concentration of 0.8 wt%.

[0125] 3) 2.0 g of soluble polyimide was weighed into a beaker at room temperature, 198 g of dichloromethane and a magnetic stirrer were added to the beaker, the beaker was placed on a magnetic stirrer, and magnetic stirring was turned on to promote the dissolution of the polyimide to obtain a polyimide solution with a total mass of 200 g and a polyimide mass percentage concentration of 1.0 wt%.

[0126] 4) Immerse the two tubular supports in the prepared aqueous solution. After 15 minutes, remove the supports and place them on a table to dry naturally until no visible solution remains on the surface. Immediately place the supports in the organic solution. The organic solution is kept at room temperature for 15 minutes. During this time, interfacial polymerization of the amino and aldehyde monomers occurs, forming a brown film on the outer surface of the tubular supports.

[0127] 5) The prepared tubular membrane was placed in a preheated constant temperature forced air drying oven for heat treatment at 200° C. for 24 h.

[0128] 6) Coating a polymer protective layer on the membrane surface to repair non-selective defects: Remove the tubular membrane from the oven. After the membrane cools to room temperature, seal one end of the membrane with a polytetrafluoroethylene membrane and secure it to the working module of the servo micron pull-up coating machine (with the closed end at the bottom). Control the pull-up machine working module so that the tubular membrane is completely immersed in the polyimide solution. Subsequently, set the pulling speed to 20μm / s and pull the membrane out of the polyimide solution. At this time, a polyimide coating will form on the outer surface of the tubular membrane. Change the pulling speed to 500μm / s to prepare the second tubular composite membrane.

[0129] 7) The prepared tubular composite membrane was dried in a fume hood for 1 day to allow the remaining solvent in the membrane to evaporate naturally. The membrane's gas separation performance was tested using a gas separation performance tester at a feed gas temperature of 150°C and a pressure of 2 bar. At a pull rate of 20 μm / s, the membrane's H2 permeability and H2 / CO2 selectivity were 81 GPU and 34.2, respectively. At a pull rate of 500 μm / s, the membrane's H2 permeability and H2 / CO2 selectivity were 221 GPU and 18.6, respectively.

[0130] Example 9

[0131] 1) At room temperature, 0.3 g each of 1,2,4,5-phenyltetramine tetrahydrochloride (BTA) and 3,3'-diaminobenzidine tetrahydrochloride hydrate (DAB) were weighed into a beaker. 29.4 g of deionized water was added to the beaker, and the beaker was placed in an ultrasonicator to promote solute dissolution, resulting in a total mass of 30 g of an aqueous solution with a BTA and DAB mass percentage concentration of 1 wt %.

[0132] 2) At room temperature, 0.24 g of terephthalaldehyde (TPA) was weighed into a beaker, 29.76 g of toluene was added to the beaker, and the beaker was placed in an ultrasonic machine to promote solute dissolution, to obtain an organic phase solution with a total mass of 30 g and a TPA mass percentage concentration of 0.8 wt%.

[0133] 3) Immerse the tubular support in the prepared aqueous solution. After 15 minutes, remove the support and place it on a table to dry naturally until no visible solution remains on the surface. Immediately place the support in the organic solution. The organic solution is left at room temperature for 15 minutes. During this time, interfacial polymerization of the amino and aldehyde monomers occurs, forming a brown film on the outer surface of the tubular support.

[0134] 4) The prepared tubular membrane was placed in a preheated constant temperature blast drying oven for heat treatment. The temperature was set to 200°C and the heat treatment time was 24 hours. Under the conditions of feed gas temperature of 150°C and pressure of 2 bar, the gas separation performance of the membrane was tested by a gas separation performance test device, and the gas separation performance of the membrane was calculated. The average values ​​of H2 permeability and H2 / CO2 selectivity of the membrane were 356GPU and 11.8 respectively. The H2 and CO2 separation performance of the mixed segment polymer separation layer is in the leading position among membranes with the same membrane area. Figure 8 As can be seen in the figure, the thickness of the mixed segment polymer separation layer is about 30-60 nm.

[0135] The technical solutions disclosed and proposed by the present invention can be implemented by those skilled in the art by drawing on the content of this document and appropriately changing the conditions, routes, and other aspects. Although the methods and preparation techniques of the present invention have been described through preferred embodiments, it is obvious that those skilled in the art can modify or recombine the methods and technical routes described herein without departing from the content, spirit, and scope of the present invention to achieve the ultimate preparation technology. It is particularly important to point out that all similar substitutions and modifications that are obvious to those skilled in the art are considered to be included in the spirit, scope, and content of the present invention.

Claims

1. A tubular composite membrane for H2 / CO2 separation, characterized in that: The composite membrane includes a support layer, a separation layer and a protective layer; wherein the support layer is a tubular inorganic support, the separation layer is a mixed segment polymer containing benzimidazole connections, and the protective layer is polyimide.

2. A tubular composite membrane for H2 / CO2 separation according to claim 1, characterized in that: The separation layer contains two or more polymer segments, and the thickness of the separation layer is 20-500 nm.

3. A method for preparing a tubular composite membrane for H2 / CO2 separation according to claim 1, characterized in that: The steps include: 1) Soaking the tubular support in an aqueous solution containing 1,2,4,5-phenylenetetramine tetrahydrochloride and 3,3'-diaminobenzidine tetrahydrochloride, allowing the aqueous solution to fully penetrate the tubular support. The tubular support is removed from the solution and allowed to dry naturally until no liquid is visible on the surface of the support. 2) immersing the support obtained in step 1) in an organic phase solution of terephthalaldehyde, wherein the amino monomer reacts with the aldehyde monomer in the organic phase solution to form a mixed segment polymer film on the surface of the support; 3) Place the tubular membrane obtained in step 2) into a preheated oven, take it out after heat treatment, and naturally cool it to room temperature; 4) Using a film-pulling coating machine, a layer of polyimide is coated on the outer surface of the tubular membrane obtained in step 3) to obtain a tubular composite membrane.

4. The method for preparing a tubular composite membrane according to claim 3, wherein: In step 1), the support is a tubular inorganic support.

5. The method for preparing a tubular composite membrane according to claim 3, wherein: In step 1), the aqueous solution contains 1,2,4,5-benzenetetramine tetrahydrochloride and 3,3'-diaminobenzidine tetrahydrochloride, with mass concentrations of 0.5wt%-2wt% respectively, and the immersion time is 1-60 minutes.

6. The method for preparing a tubular composite membrane according to claim 3, wherein: In step 2), the solute of the organic phase solution is terephthalaldehyde, the solvent is toluene, the reaction time is 1-120 minutes, and the mass concentration of terephthalaldehyde is 0.5wt%-2wt%.

7. The method for preparing a tubular composite membrane according to claim 3, wherein: In step 2), the amino monomer in the aqueous solution and the aldehyde monomer in the organic solution undergo interfacial polymerization to form a mixed segment polymer film on the outer surface of the tubular support.

8. The method for preparing a tubular composite membrane according to claim 3, wherein: The tubular membrane obtained by the interfacial polymerization reaction in step 3) needs to be placed in a preheated oven at 100-250° C. for high-temperature heat treatment for 1-48 hours.

9. The method for preparing a tubular composite membrane according to claim 3, wherein: Step 4) The coating method is a pulling method with a pulling speed of 20-500 μm / s. The solute of the polymer solution used for the coating is soluble polyimide, the solvent is dichloromethane, and the mass concentration of the polyimide is in the range of 0.1-5 wt%.

10. The tubular composite membrane of claim 1 is used for separation of H2 / CO2 mixed gases at different temperatures and pressures.

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