Composite hollow fiber membrane, method for producing the same, membrane module, and method for separating acid gas

Abstract

The present application relates to the technical field of membrane separation, in particular to a composite hollow fiber membrane, a preparation method thereof, a membrane module and a method for separating acid gas. The composite hollow fiber membrane comprises a modified poly-C2-C4 olefin hollow fiber membrane and a selective separation layer. By limiting specific components and specific contents of each component in the modified poly-C2-C4 olefin hollow fiber membrane, the modified poly-C2-C4 olefin hollow fiber membrane has persistent hydrophilicity, and the hydrophilicity of both sides of the membrane and the pore wall of the membrane is uniform. Meanwhile, the selective separation layer is loaded on the modified poly-C2-C4 olefin hollow fiber membrane, and the selective separation layer is prepared from a composition II containing an amine group polymer and a nitrogen-containing organic small molecule, which can be used for selective desulfurization and / or decarburization from a mixed gas containing acid gas. The composite hollow fiber membrane is assembled into a membrane module for selective removal of acid gas, which effectively improves the removal efficiency of acid gas.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of membrane separation technology, in particular to a composite hollow fiber membrane and a preparation method thereof, a membrane module and a method for separating acid gas. BACKGROUND

[0002] Poly-lower alkene material has the advantages of non-toxicity, wide raw material sources and good chemical stability, and is a kind of widely used polymer material. Polyethylene has excellent processing performance, and can be formed into a microporous membrane filtration material with separation function through swelling, extrusion, stretching, thermal phase separation and the like. Compared with poly-sulfone, poly-ether sulfone, poly-vinylidene fluoride, cellulose acetate and polyimide membrane materials, the poly-lower alkene membrane is low in price. The poly-lower alkene separation membrane is widely used in the field of water treatment, but there is no relevant report in the field of selective separation of gas.

[0003] On the other hand, hydrophilic hollow fiber membranes such as cellulose acetate and polyimide have been widely used in the field of selective decarburization of natural gas and biogas purification, but the membrane module of this type is expensive, only a few large foreign companies provide complete equipment, and the separation membrane has limited performance and cannot selectively remove acid gas from a gas source containing H2. This is mainly because cellulose acetate and polyimide separation membranes rely on the dissolution and diffusion of acid gases such as CO2 in the membrane to separate them from the main molecules, which has a Robinson upper limit. The fixed carrier membrane is a membrane material that can break through the Robinson upper limit. It utilizes the reaction of acid gas molecules with carriers such as NH2 - , COO - in the membrane material, and simultaneously utilizes the reaction selectivity and dissolution selectivity to achieve the enhanced selective separation of acid gas. CN104801207A discloses a polyethylene amine / polyaniline mixed matrix flat membrane, which uses poly-sulfone or poly-ether sulfone as an ultrafiltration base film and can be used to remove CO2 from a gas source containing N2; CN102580563A discloses a polyethylene amine matrix flat membrane modified by a small molecule amine and used for CO2 / N2 separation; CN102886212A, CN101596412A, CN101596411A, CN1171665C and CN1180878C all disclose flat separation membranes for selective separation of CO2 based on the reaction selectivity effect.

[0004] The membrane modules disclosed in the above prior art are all flat roll-type membranes, and are supported by expensive materials such as poly-sulfone and poly-ether sulfone. However, the packing density of flat membranes is limited, and is less than 1000 m 2 / m 3 . Compared with flat membrane modules, the packing density of hollow fiber membranes can reach 1600-3000 m 2 / m 3, and can greatly reduce investment, equipment size and floor area under the same processing scale.

[0005] Therefore, there is an urgent need for a poly-C2-C4 olefin-based composite hollow fiber membrane to solve the problems of low packing density and large equipment investment of existing flat membrane modules. SUMMARY

[0006] The purpose of the present application is to overcome the problems of low packing density and large equipment investment of existing flat membrane modules, and to provide a composite hollow fiber membrane and its preparation method, a membrane module, and a method for separating acid gas. The composite hollow fiber membrane has a high packing density. The membrane module containing the composite hollow fiber membrane is used for separating acid gas, and the acid gas has a large permeation performance and separation factor, thereby significantly improving the separation efficiency of the acid gas.

[0007] To achieve the above-mentioned purpose, the first aspect of the present application provides a composite hollow fiber membrane, which comprises: a modified poly-C2-C4 olefin hollow fiber membrane and a selective separation layer loaded on the modified poly-C2-C4 olefin hollow fiber membrane; the modified poly-C2-C4 olefin hollow fiber membrane is prepared from a composition I containing poly-C2-C4 olefin, amphiphilic polymer and nanoparticles;

[0008] wherein, based on the total weight of the modified poly-C2-C4 olefin hollow fiber membrane, the content of the poly-C2-C4 olefin is 65-85 wt%, the content of the amphiphilic polymer is 6-35 wt%, and the content of the nanoparticles is 1-3 wt%;

[0009] wherein, the selective separation layer is prepared from a composition II containing amine group-containing polymer and nitrogen-containing organic small molecule.

[0010] The second aspect of the present application provides a preparation method of a composite hollow fiber membrane, which comprises the following steps:

[0011] (1) melt blending, twin-screw extrusion, melt spinning, drawing and heat treatment are sequentially performed on the composition I containing poly-C2-C4 olefin, amphiphilic polymer and nanoparticles in the presence of inert gas to obtain a modified poly-C2-C4 olefin hollow fiber membrane;

[0012] (2) a casting solution containing composition II is coated on the surface of the modified poly-C2-C4 olefin hollow fiber membrane, and then dried to form a selective separation layer on the surface of the modified poly-C2-C4 olefin hollow fiber membrane to obtain a composite hollow fiber membrane;

[0013] wherein, in the composition I, the weight ratio of the poly-C2-C4 olefin, amphiphilic polymer and nanoparticles is 65-85: 6-35: 1-3;

[0014] The composition II contains an amine group-containing polymer and a nitrogen-containing organic small molecule.

[0015] The third aspect of the present application provides a membrane module containing the composite hollow fiber membrane provided by the first aspect and / or the composite hollow fiber membrane prepared by the method provided by the second aspect.

[0016] The fourth aspect of the present application provides a method for separating acid gas, which comprises: introducing a mixed gas containing acid gas into the membrane module provided by the third aspect for separation.

[0017] Compared with the prior art, the present application has the following advantages:

[0018] (1) The composite hollow fiber membrane provided by the present application contains a modified poly-C2-C4 olefin hollow fiber membrane and a selective separation layer. By limiting the specific components and specific contents of each component in the modified poly-C2-C4 olefin hollow fiber membrane, the modified poly-C2-C4 olefin hollow fiber membrane has persistent hydrophilicity, and the hydrophilicity on both sides of the membrane and the pore wall of the membrane is uniform. At the same time, the modified poly-C2-C4 olefin hollow fiber membrane is functionalized, i.e. the selective separation layer is loaded on the modified poly-C2-C4 olefin hollow fiber membrane, and the selective separation layer is prepared from a composition II containing an amine group-containing polymer and a nitrogen-containing organic small molecule, which can be used for selective desulfurization and / or decarburization from a mixed gas containing acid gas.

[0019] (2) The preparation method of the composite hollow fiber membrane provided by the present application utilizes the advantages of low cost, good processability and good chemical stability of the poly-C2-C4 olefin hollow fiber membrane, and the advantages of the poly-C2-C4 olefin hollow fiber membrane and the fixed carrier membrane. The poly-C2-C4 olefin hollow fiber membrane is hydrophilically modified to prepare a modified poly-C2-C4 olefin hollow fiber membrane to form a porous support layer. A casting solution containing composition II (amine group-containing polymer and nitrogen-containing organic small molecule) is coated on the surface of the modified poly-C2-C4 olefin hollow fiber membrane to form a selective separation layer, thereby preparing a composite hollow fiber composite membrane.

[0020] (3) The composite hollow fiber membrane provided by the present application is assembled into a membrane module for selective removal of acid gas, which can effectively improve the permeation performance parameters and separation factor of acid gas, i.e. effectively improves the removal efficiency of acid gas. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 is the SEM image of the cross section of the composite hollow fiber membrane prepared in Example 1. DETAILED DESCRIPTION

[0022] The endpoints of the ranges and any values disclosed herein are not limited to the precise values recited as the exact dimensions are not critical to the invention. Any numeric range recited is intended to include all values from the lower value to the upper value, inclusive of both values, and to also include any value approximately or about the value. For ranges including upper and lower limits, the range can also include the endpoints of the range, and all the other values therebetween. For ranges excluding the endpoints, the range includes all values therebetween.

[0023] The first aspect of the present application provides a composite hollow fiber membrane, comprising: a modified poly-C2-C4 olefin hollow fiber membrane and a selective separation layer loaded on the modified poly-C2-C4 olefin hollow fiber membrane; the modified poly-C2-C4 olefin hollow fiber membrane is prepared from a composition I containing poly-C2-C4 olefin, amphiphilic polymer and nanoparticles;

[0024] wherein, based on the total weight of the modified poly-C2-C4 olefin hollow fiber membrane, the content of the poly-C2-C4 olefin is 65-85 wt%, the content of the amphiphilic polymer is 6-35 wt%, and the content of the nanoparticles is 1-3 wt%.

[0025] wherein, the selective separation layer is prepared from a composition II containing amine group-containing polymer and nitrogen-containing organic small molecule.

[0026] In the present application, the amphiphilic polymer refers to a polymer containing hydrophilic and hydrophobic properties, unless otherwise specified.

[0027] In some embodiments of the present application, preferably, based on the total weight of the modified poly-C2-C4 olefin hollow fiber membrane, the content of the poly-C2-C4 olefin is 65-80 wt%, the content of the amphiphilic polymer is 19-32 wt%, and the content of the nanoparticles is 1-3 wt%; further preferably, based on the total weight of the modified poly-C2-C4 olefin hollow fiber membrane, the content of the poly-C2-C4 olefin is 68-80 wt%, the content of the amphiphilic polymer is 19-30 wt%, and the content of the nanoparticles is 1-2 wt%. With the preferred specific content, the modified poly-C2-C4 olefin hollow fiber membrane has the advantages of good air permeability, strong hydrophilicity, long-term stability, firm coating, etc., and can be used for selectively separating acidic gases such as CO2 and H2S.

[0028] In some embodiments of the present application, preferably, the modified poly(C2-C4)olefin hollow fiber membrane is prepared from a combination of poly(C2-C4)olefin, amphiphilic polymer and nanoparticles, wherein the content of the poly(C2-C4)olefin is 65-80 wt%, the content of the amphiphilic polymer is 19-32 wt%, and the content of the nanoparticles is 1-3 wt%, based on the total weight of the modified poly(C2-C4)olefin hollow fiber membrane.

[0029] In some embodiments of the present application, the weight average molecular weight of the poly(C2-C4)olefin is 1x10 4 -5x10 6 g / mol, for example, 1x10 4 g / mol, 1x10 5 g / mol, 1x10 6 g / mol, 3x10 6 g / mol, 5x10 6 g / mol, and any value in the range between any two of the cited values, preferably 8x10 4 -3x10 6 g / mol; and the density is 0.9-0.98 g / cm 3 , for example, 0.9 g / cm 3 , 0.92 g / cm 3 , 0.93 g / cm 3 , 0.95 g / cm 3 , 0.96 g / cm 3 , 0.97 g / cm 3 , and 0.98 g / cm 3 , and any value in the range between any two of the cited values, preferably 0.92-0.95 g / cm 3 .

[0030] In the present application, the poly(C2-C4)olefin can be selected from a wide range of types, as long as the weight average molecular weight and the density of the poly(C2-C4)olefin meet the above-mentioned limitations. In the present application, the poly(C2-C4)olefin can be selected from a wide range of sources. The poly(C2-C4)olefin can be obtained commercially or by self-preparation.

[0031] In some embodiments of the present application, preferably, in the amphiphilic polymer, the weight ratio of the hydrophilic group to the hydrophobic group is 20-50:50-80, for example, 20:80, 30:70, 40:60, 50:50, and any value in the range between any two of the cited values, preferably 25-35:65-75.

[0032] In the present application, the strong interaction between the hydrophobic group and the hydrophilic group in the amphiphilic polymer increases the binding ability of the hydrophobic group to the poly-C2-C4 olefin in the amphiphilic polymerization, and the hydrophilic group in the amphiphilic polymer further improves the hydrophilicity of the poly-C2-C4 olefin.

[0033] In some embodiments of the present application, preferably, in the amphiphilic polymer, the hydrophilic group is selected from at least one of polyoxyethylene, polyacrylic acid, polyacrylamide, polyvinyl alcohol, polyamide and polyurethane, and preferably is polyoxyethylene; the hydrophobic group is selected from at least one of polyoxypropylene, polyamide, polycarbonate, polyacrylonitrile and polyester, and preferably is polyoxypropylene.

[0034] In a specific embodiment of the present application, the amphiphilic polymer is a polymer containing polyoxyethylene and polyoxypropylene; wherein the weight ratio of polyoxyethylene to polyoxypropylene in the amphiphilic polymer is 20-50:50-80.

[0035] In some embodiments of the present application, preferably, the weight average molecular weight of the amphiphilic polymer is 1x10 3 -2x10 4 g / mol, for example, 1x10 3 g / mol, 3x10 3 g / mol, 5x10 3 g / mol, 8x10 3 g / mol, 1x10 4 g / mol, 2x10 4 g / mol, and any value in the range between any two values, and preferably 5x10 3 -1x10 4 g / mol.

[0036] In the present application, the type of the amphiphilic polymer has a wide selection range, as long as the weight ratio of the hydrophilic group to the hydrophobic group and the weight average molecular weight in the amphiphilic polymer meet the above-mentioned limitations. Preferably, the amphiphilic polymer is selected from at least one of polyoxyethylene-polyoxypropylene diblock copolymer, polyacrylic acid-polyamide copolymer, polyvinyl alcohol-polycarbonate copolymer, polyamide-polyacrylonitrile copolymer, polyurethane-polyester copolymer, polyacrylic acid-polycarbonate copolymer, polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer and double-end butyl or hydroxyl-terminated butyl polyoxyethylene-polyoxypropylene copolyether.

[0037] In the present application, without special circumstances, the nanoparticles as the hydrophilic nanoparticles can strengthen the hydrophilicity of the amphiphilic polymer and improve the strength of the modified poly-C2-C4 olefin hollow fiber membrane.

[0038] In some embodiments of the present application, preferably, the average particle size of the nanoparticles is 5-100 nm, for example, 5 nm, 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm and 100 nm, and any value in the range between any two of the aforementioned values, preferably 20-100 nm. With the preferred conditions, the hydrophilic property and the strength of the modified poly-C2-C4 olefin hollow fiber membrane are more favorably improved.

[0039] In the present application, the type of the nanoparticles has a wide selection range. Preferably, the nanoparticles are selected from at least one of nano-silica, nano-alumina, nano-titania, nano-barium titanate and nano-strontium titanate.

[0040] In the present application, the selective separation layer is prepared from the composition II containing an amine-based polymer and a nitrogen-containing organic small molecule, preferably, the selective separation layer is prepared from the composition II containing an amine-based polymer and a nitrogen-containing organic small molecule.

[0041] In some embodiments of the present application, preferably, the content of the amine-based polymer is 60-90 wt%, preferably 70-80 wt%, and the content of the nitrogen-containing organic small molecule is 10-40 wt%, preferably 20-30 wt%, based on the total weight of the selective separation layer.

[0042] In some embodiments of the present application, the molar ratio of the amine-based polymer to the nitrogen-containing organic small molecule in the composition II is 1:1-5, for example, 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:4, 1:5, and any value in the range between any two of the aforementioned values, preferably 1:1-3. With the preferred molar ratio, the permeation property and the separation factor of the acid gas when the composite hollow fiber membrane is used for acid gas separation are more favorably improved.

[0043] In some embodiments of the present application, preferably, the weight average molecular weight of the amine-based polymer is 1500-8000 g / mol, for example, 1500 g / mol, 2000 g / mol, 2500 g / mol, 3000 g / mol, 3500 g / mol, 4000 g / mol, 6000 g / mol and 8000 g / mol, and any value in the range between any two of the aforementioned values, preferably 2000-4000 g / mol; further preferably, the amine-based polymer is selected from at least one of polyacrylamide, polyvinylamine, polyethyleneimine and polyaniline.

[0044] In the present application, the purpose of the nitrogen-containing organic small molecule is to enhance the number of functional groups in the base polymer, which is conducive to the transmembrane transfer of acid gas. Preferably, the nitrogen-containing organic small molecule is selected from at least one of ethylenediamine, piperazine, diethanolamine, hydroxyethyl diamine and urethane.

[0045] According to the present application, preferably, the packing density of the composite hollow fiber membrane is 1500-3000 m 2 / m 3 , preferably 1800-2100 m 2 / m 3 ; the pressure resistance is 10-15 MPa, preferably 11-13 MPa.

[0046] According to the present application, preferably, the outer diameter of the composite hollow fiber membrane is 1-5 mm, preferably 2-4 mm; the central hole diameter is 0.2-4 mm, preferably 0.6-2 mm; the thickness is 400-1000 μm, preferably 600-800 μm.

[0047] In the present application, the outer diameter parameter, the thickness parameter and the central hole diameter parameter are measured by electron microscope observation method without special circumstances.

[0048] According to the present application, preferably, the average pore size of the modified poly-C2-C4 olefin hollow fiber membrane is 1-5 mm, preferably 2-3 mm; the porosity is 60-90%, preferably 65-75%. Among them, the average pore size parameter is measured by electron microscope observation method; the porosity parameter is measured by mercury injection method.

[0049] According to the present application, preferably, the average thickness of the selective separation layer is 100-900 μm, preferably 200-800 μm. Among them, the average thickness of the selective separation layer is measured by electron microscope observation method.

[0050] According to the present application, preferably, the thickness ratio of the modified poly-C2-C4 olefin hollow fiber membrane and the selective separation layer is 1-4:1, for example, 1:1, 2:1, 3:1, 4:1, and any value in the range of any two numerical values, preferably 2-3:1.

[0051] According to a particularly preferred embodiment of the present application, the composite hollow fiber membrane provided by the present application comprises: a modified poly-C2-C4 olefin hollow fiber membrane and a selective separation layer loaded on the modified poly-C2-C4 olefin hollow fiber membrane; the modified poly-C2-C4 olefin hollow fiber membrane is prepared from a combination of poly-C2-C4 olefin, amphiphilic polymer and nanoparticles I;

[0052] The content of the poly-C2-C4 olefin is 65-80 wt%, the content of the amphiphilic polymer is 19-32 wt%, and the content of the nanoparticles is 1-3 wt%, based on the total weight of the modified poly-C2-C4 olefin hollow fiber membrane;

[0053] The selective separation layer is prepared from a combination of an amine-based polymer and a nitrogen-containing organic small molecule, which is composition II.

[0054] The weight ratio of the hydrophilic group and the hydrophobic group in the amphiphilic polymer is 20-50: 50-80.

[0055] The content of the amine-based polymer is 60-90 wt%, and the content of the nitrogen-containing organic small molecule is 10-40 wt%, based on the total weight of the selective separation layer.

[0056] The second aspect of the present application provides a preparation method of a composite hollow fiber membrane, which comprises the following steps:

[0057] (1) In the presence of an inert gas, composition I containing poly-C2-C4 olefin, amphiphilic polymer and nanoparticles is sequentially subjected to melt blending, twin-screw extrusion, melt spinning, drawing and heat treatment to obtain a modified poly-C2-C4 olefin hollow fiber membrane.

[0058] (2) A casting solution containing composition II is coated on the surface of the modified poly-C2-C4 olefin hollow fiber membrane, and then dried to form a selective separation layer on the surface of the modified poly-C2-C4 olefin hollow fiber membrane to obtain a composite hollow fiber membrane.

[0059] The weight ratio of the poly-C2-C4 olefin, amphiphilic polymer and nanoparticles in the composition I is 65-85: 6-35: 1-3.

[0060] The composition II contains an amine-based polymer and a nitrogen-containing organic small molecule.

[0061] In the present application, unless otherwise specified, the inert gas is selected from at least one of nitrogen, helium, argon and neon, preferably nitrogen.

[0062] In the present application, unless otherwise specified, the physical property parameters and specific types of the poly-C2-C4 olefin, amphiphilic polymer and nanoparticles are in accordance with the above-mentioned limitations, which are not repeated here.

[0063] In the present application, unless otherwise specified, the physical property parameters and specific types of the amine-based polymer and nitrogen-containing organic small molecule are in accordance with the above-mentioned limitations, which are not repeated here.

[0064] In some embodiments of the present invention, preferably, the weight ratio of the polyC2-C4 olefin, the amphiphilic polymer, and the nanoparticles in composition I is 65-85:6-35:1-3, more preferably 65-80:19-32:1-3, and even more preferably 68-80:19-30:1-2. Using the preferred weight ratio is more beneficial for improving the separation effect of the composite hollow fiber membrane on acidic gases such as CO2 and H2S.

[0065] In this invention, the melt blending conditions have a wide range of selection, as long as the polyethylene, amphiphilic polymer, and nanoparticles are mixed evenly. Preferably, in step (1), the melt blending conditions include: a temperature of 250-350℃, for example, 250℃, 270℃, 280℃, 290℃, 300℃, 310℃, 320℃, 350℃, and any value within any range of any two values, preferably 270-320℃; and a time of 30-180min, for example, 30min, 50min, 60min, 70min, 80min, 90min, 100min, 150min, 180min, and any value within any range of any two values, preferably 50-90min.

[0066] In this invention, the twin-screw extrusion is intended to extrude the blend obtained from the melt blending into granules using a twin-screw extruder. Preferably, in step (1), the conditions for the twin-screw extrusion include: a temperature of 180-240°C and a rotation speed of 300-900 rpm.

[0067] In some embodiments of the present invention, preferably, in step (1), the spinneret core liquid in the melt spinning is nitrogen gas, and the pressure of the nitrogen gas is 0.15-0.35 MPa, for example, 0.15 MPa, 0.2 MPa, 0.3 MPa, 0.35 MPa, and any value in the range of any two values, preferably 0.2-0.35 MPa.

[0068] In this invention, unless otherwise specified, the melt spinning is performed in a melt spinning machine.

[0069] In one specific embodiment of the present invention, the granules obtained by the twin-screw extrusion are metered by a metering pump and then enter a spinneret for melt spinning with nitrogen gas at 0.15-0.35 MPa as the core liquid to obtain nascent fibers.

[0070] In the present application, the drawing is intended to draw the nascent fiber obtained by melt spinning to draw holes. Preferably, in step (1), the draw ratio is 500-3000, for example, 500, 800, 1000, 1500, 2000, 2500, 3000, and any value in the range between any two numerical values, preferably 2000-3000.

[0071] In the present application, the drawing is carried out in a five-roller drawing machine without special circumstances.

[0072] In the present application, the heat treatment is intended to improve the crystallinity of the polymer chain segment in the modified poly-C2-C4 olefin hollow fiber membrane, improve the fiber strength and the mixing uniformity of small molecules. Preferably, in step (1), the heat treatment conditions include: the temperature is 100-160℃, for example, 100℃, 120℃, 130℃, 140℃, 150℃, 160℃, and any value in the range between any two numerical values, preferably 120-150℃; the time is 1-10min, for example, 1min, 2min, 3min, 4min, 5min, 6min, 8min, 10min, and any value in the range between any two numerical values, preferably 2-3min.

[0073] In some embodiments of the present application, preferably, in the casting solution, the concentration of the composition II is 0.5-9wt%, for example, 0.5wt%, 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, 7wt% and 9wt%, and any value in the range between any two numerical values, preferably 1-5wt%. In the present application, the concentration of the composition II refers to the sum of the concentrations of the amine-based polymer and the nitrogen-containing organic small molecule.

[0074] In some embodiments of the present application, preferably, in the composition II, the molar ratio of the amine-based polymer and the nitrogen-containing organic small molecule is 1:1-5, for example, 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:4, 1:5, and any value in the range between any two numerical values, preferably 1:1-3.

[0075] In some embodiments of the present application, preferably, the casting solution is mixed by an aqueous solution containing the amine-based polymer and the nitrogen-containing organic small molecule; further preferably, in the aqueous solution containing the amine-based polymer, the concentration of the amine-based polymer is 2-6wt%, for example, 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, and any value in the range between any two numerical values.

[0076] According to a specific embodiment of the present application, an aqueous solution containing amine-based compounds with a concentration of 2-6 wt% and a nitrogen-containing small organic molecule are mixed to obtain a casting solution, wherein the molar ratio of the amine-based compounds to the nitrogen-containing small organic molecule in the aqueous solution containing amine-based compounds is 1:1-5, preferably 1:1-3; and the concentration of the composition II in the casting solution is 1-5 wt%.

[0077] In some embodiments of the present application, preferably, the use ratio of the casting solution in mL to the modified poly-C2-C4 olefin hollow fiber membrane in g is 0.1-0.6:1, preferably 0.2-0.4:1. Wherein, the use ratio refers to that the use amount of the casting solution is 0.1-0.6 mL, for example, 0.1 mL, 0.2 mL, 0.3 mL, 0.4 mL, 0.5 mL, 0.6 mL, and any value in the range between any two numerical values, preferably 0.2-0.4 mL, corresponding to 1 g of the modified poly-C2-C4 olefin hollow fiber membrane.

[0078] In the present application, the drying treatment is intended to remove the solvent in the casting solution containing the polymer. Preferably, in step (2), the conditions of the drying treatment include: relative humidity of 20-80%, for example, 20%, 35%, 45%, 55%, 60%, 80%, and any value in the range between any two numerical values, preferably 35-60%; temperature of 15-60℃, for example, 15℃, 25℃, 30℃, 35℃, 40℃, 45℃, 60℃, and any value in the range between any two numerical values, preferably 25-45℃; time of 5-30 h, for example, 5 h, 8 h, 10 h, 15 h, 20 h, 24 h, 30 h, and any value in the range between any two numerical values, preferably 8-24 h.

[0079] The third aspect of the present application provides a membrane module containing the composite hollow fiber membrane provided by the first aspect and / or the composite hollow fiber membrane prepared by the method provided by the second aspect.

[0080] According to the present application, preferably, the membrane module is assembled from the composite hollow fiber membrane provided by the present application, and one end of the composite hollow fiber membrane is closed.

[0081] The fourth aspect of the present application provides a method for separating acid gas, which comprises: passing a mixed gas containing acid gas into the membrane module provided by the third aspect for separation.

[0082] The composite hollow fiber membrane has a composite structure, and is composed of a modified poly-C2-C4 olefin hollow fiber membrane with a highly developed pore structure and a dense selective separation layer from inside to outside; wherein the selective separation layer realizes selective separation by using the solubility difference of the acid gas, and the modified poly-C2-C4 olefin hollow fiber membrane is a pressure-resistant support layer, which is beneficial to gas permeation and improving gas flux.

[0083] In some embodiments of the present application, the mixed gas further contains at least one of N2, H2 and CH4.

[0084] In the present application, unless otherwise specified, the acid gas is at least one of CO2, H2S and SO2.

[0085] In some embodiments of the present application, preferably, the volume content of the acid gas in the mixed gas is 1-50 vol%, for example, 1 vol%, 10 vol%, 15 vol%, 20 vol%, 25 vol%, 30 vol%, 35 vol%, 40 vol% and 50 vol%, and any value in the range formed by any two numerical values, preferably 10-40 vol%.

[0086] In a specific embodiment of the present application, the composite hollow fiber membrane provided by the present application is assembled into a membrane module, and a mixed gas with an acid gas content of 1-50 vol% is introduced into the membrane module for separation, wherein the permeation performance of the acid gas is 300-2600 cm 3 (STP) / (cm 2 ·s·cmHg), and the separation factor of the acid gas / other gas is 20-70:1.

[0087] The present application will be described in detail below through examples.

[0088] The outer diameter parameter, thickness parameter and center hole diameter parameter of the composite hollow fiber membrane are measured by an electron microscope observation method;

[0089] The average pore diameter parameter of the modified poly-C2-C4 olefin hollow fiber membrane is measured by an electron microscope observation method;

[0090] The porosity parameter of the modified poly-C2-C4 olefin hollow fiber membrane is measured by a mercury injection method;

[0091] The average thickness parameter of the selective separation layer is measured by an electron microscope observation method.

[0092] The related physical property parameters of the composite hollow fiber membranes (S1-S10 and DS1-DS3) prepared in Examples 1-10 and Comparative Examples 1-3 are listed in Table 1.

[0093] Example 1

[0094] (1) In a nitrogen atmosphere, 65 parts by weight of polyethylene (weight average molecular weight of 10) 4 g / mol, density 0.9 g / cm³ 3 ), 33 parts by weight of amphiphilic polymer (polyoxyethylene-polyoxypropylene copolymer, weight average molecular weight of 5×10⁻⁶) 3 Two parts by weight of nanoparticles (nano silica, with an average particle size of 20-40 nm) were melt-blended at 270 °C for 90 min. The resulting blend was then extruded by a twin-screw extruder at 180 °C and 400-600 rpm. The resulting particles were metered by a metering pump and fed into the spinneret of a melt spinning machine. The spinneret was melt-spun using nitrogen gas at 0.15 MPa as the core liquid. The resulting nascent fibers were drawn into pores by a five-roller drawing machine at a drawing rate of 500 times and then heat-treated at 120 °C for 120 s to obtain a modified polyethylene hollow fiber membrane.

[0095] Based on the total weight of the modified polyethylene hollow fiber membrane, the content of polyethylene is 65 wt%, the content of amphiphilic polymer is 33 wt% (the content of polyoxyethylene is 6.6 wt%, the content of polyoxypropylene is 26.4 wt%), and the content of nanoparticles is 2 wt%.

[0096] (2) A 2 wt% aqueous solution of polyacrylamide and ethylenediamine were mixed to obtain a 1 wt% casting solution; wherein the weight-average molecular weight of polyacrylamide was 5000 g / mol, and the molar ratio of polyacrylamide to ethylenediamine in the aqueous solution of polyacrylamide was 1:1.

[0097] (3) After coating the above casting solution onto the surface of the above modified polyethylene hollow fiber membrane, wherein the ratio of the casting solution in mL to the modified polyethylene hollow fiber membrane in g is 0.2:1, the membrane is dried for 12 hours in an environment with a relative humidity of 40% and a temperature of 35°C to form a selective separation layer on the surface of the modified polyethylene hollow fiber membrane, thereby obtaining a composite hollow fiber membrane S1.

[0098] In the selective separation layer, the content of polyacrylamide is 70 wt% and the content of ethylenediamine is 30 wt%.

[0099] The SEM image of the composite hollow fiber membrane S1 is shown below. Figure 1 As shown, by Figure 1 It can be seen that the composite hollow fiber membrane S1 has a composite structure, consisting of modified polyethylene hollow fibers with a highly developed pore structure and a dense selective separation layer from the inside out.

[0100] Example 2

[0101] (1) 70 parts by weight of polypropylene (weight average molecular weight: 10 5 g / mol, density: 0.95 g / cm 3 ), 29 parts by weight of an amphiphilic polymer (polyacrylic acid-polyamide copolymer, weight average molecular weight: 2 x 10 4 g / mol, weight ratio of polyacrylic acid and polyamide: 30:70), and 1 part by weight of nanoparticles (nano-alumina, average particle diameter: 5 nm) were melt-blended at 290°C for 70 minutes in a nitrogen atmosphere, the obtained blend was subjected to twin-screw extrusion at a temperature of 200°C and a rotation speed of 300 rpm, the obtained pellets were metered by a metering pump and then introduced into a spinneret of a melt spinning machine, melt spinning was performed using nitrogen gas at 0.2 MPa as a core liquid, the obtained nascent fiber was drawn at a draw ratio of 1000 times by a five-roll draw machine, and heat treatment was performed at 128°C for 190 seconds, thereby obtaining a modified polypropylene hollow fiber membrane;

[0102] The content of polypropylene was 70 wt% and the content of amphiphilic polymer was 29 wt% (the content of polyacrylic acid was 8.7 wt% and the content of polyamide was 20.3 wt%) based on the total weight of the modified polypropylene hollow fiber membrane, and the content of nanoparticles was 1 wt%.

[0103] (2) A polyvinylamine aqueous solution having a concentration of 2.5 wt% was mixed with diethanolamine to obtain a casting solution having a concentration of 0.5 wt%; the weight average molecular weight of the polyvinylamine was 1000 g / mol, and the molar ratio of polyvinylamine to diethanolamine in the polyvinylamine aqueous solution was 1:1.

[0104] (3) The casting solution was coated on the surface of the modified polypropylene hollow fiber membrane, and then dried in an environment having a relative humidity of 35% and a temperature of 25°C for 18 hours, so as to form a selective separation layer on the surface of the modified polypropylene hollow fiber membrane, thereby obtaining a composite hollow fiber membrane S2.

[0105] The content of polyvinylamine in the selective separation layer was 60 wt% and the content of diethanolamine was 40 wt%.

[0106] The SEM image of the composite hollow fiber membrane S2 was similar to Figure 1 .

[0107] Example 3

[0108] (1) 75 parts by weight of polybutadiene (weight average molecular weight: 2 x 10 6 g / mol, density: 0.98 g / cm3 ), 22 parts by weight of the amphiphilic polymer (polyvinyl alcohol-polycarbonate copolymer, weight average molecular weight of 2×10⁻⁶). 4 The following ingredients were melt-blended at 300℃ for 80 min: g / mol of polyvinyl alcohol and polycarbonate in a weight ratio of 40:60 and 3 parts by weight of nanoparticles (nano barium titanate, with an average particle size of 50 nm). The resulting blend was extruded by a twin-screw extruder at a temperature of 220℃ and a speed of 800 rpm. The resulting particles were metered by a metering pump and then fed into the spinneret of a melt spinning machine. Melt spinning was performed using nitrogen gas at 0.25 MPa as the core liquid. The resulting nascent fibers were drawn into pores by a five-roller drawing machine at a drawing rate of 1500 times and then heat-treated at 135℃ for 240 s to obtain a modified butadiene hollow fiber membrane.

[0109] Based on the total weight of the modified polybutadiene hollow fiber membrane, the content of polybutadiene is 75 wt%, the content of amphiphilic polymer is 22 wt% (the content of polyvinyl alcohol is 8.8 wt%, the content of polycarbonate is 13.2 wt%), and the content of nanoparticles is 3 wt%.

[0110] (2) Mix a 3 wt% aqueous solution of polyethyleneimine and piperazine to obtain a 5 wt% casting solution; wherein the weight-average molecular weight of polyethyleneimine is 6000 g / mol, and the molar ratio of polyethyleneimine to piperazine in the aqueous solution of polyethyleneimine is 1:1.

[0111] (3) After coating the above casting solution onto the surface of the above modified polybutadiene hollow fiber membrane, wherein the ratio of the casting solution in mL to the modified polybutadiene hollow fiber membrane in g is 0.6:1, the membrane is dried for 20 hours in an environment with a relative humidity of 45% and a temperature of 38°C to form a selective separation layer on the surface of the modified polybutadiene hollow fiber membrane, thereby obtaining a composite hollow fiber membrane S3.

[0112] In the selective separation layer, the content of polyethyleneimine is 80 wt% and the content of piperazine is 20 wt%.

[0113] Among them, the SEM image of the composite hollow fiber membrane S3 is... Figure 1 similar.

[0114] Example 4

[0115] The method is the same as in Example 3, except that in step (1), 22 parts by weight of the amphiphilic polymer (polyvinyl alcohol-polycarbonate copolymer, weight-average molecular weight of 2×10⁻⁶) is used. 4and 3 parts by weight of nanoparticles (nano-barium titanate, average particle size of 50 nm) were replaced with 23 parts by weight of an amphiphilic polymer (diblock butyl polyoxyethylene-polyoxypropylene copolyether, weight average molecular weight of 8 x 10 3 and 2 parts by weight of nanoparticles (nano-barium titanate, average particle size of 80 nm), and the remaining steps were the same, to obtain a composite hollow fiber membrane S4.

[0116] The content of polybutadiene was 75 wt%, the content of the amphiphilic polymer was 23 wt% (the content of polyoxyethylene was 9.2 wt%, and the content of polyoxypropylene was 13.8 wt%), and the content of the nanoparticles was 2 wt%, based on the total weight of the modified polybutadiene hollow fiber membrane.

[0117] Example 5

[0118] (1) 68 parts by weight of polypropylene (weight average molecular weight of 5 x 10 5 g / mol, density of 0.96 g / cm 3 ), 30 parts by weight of an amphiphilic polymer (polyphthalamide-polyacrylonitrile copolymer, weight average molecular weight of 2 x 10 4 g / mol, weight ratio of polyphthalamide to polyacrylonitrile of 50:50), and 2 parts by weight of nanoparticles (nano-strontium titanate, average particle size of 100 nm) were melt-blended at 300°C for 90 min, the obtained blend was subjected to double-screw extrusion at a temperature of 230°C and a rotation speed of 900 rpm, the obtained particles were metered by a metering pump and then entered the spinneret of a melt spinning machine, melt spinning was performed with 0.35 MPa nitrogen gas as the core liquid, the obtained nascent fiber was stretched at a draw ratio of 2000 times by a five-roller drafting machine, and heat treatment was performed at 140°C for 300 s, to obtain a modified polypropylene hollow fiber membrane;

[0119] The content of polypropylene was 68 wt%, the content of the amphiphilic polymer was 30 wt% (the content of polyphthalamide was 15 wt%, and the content of polyacrylonitrile was 15 wt%), and the content of the nanoparticles was 2 wt%, based on the total weight of the modified polypropylene hollow fiber membrane.

[0120] (2) A polyaniline aqueous solution with a concentration of 5 wt% and hydroxyethyl diamine were mixed to obtain a casting solution with a concentration of 9 wt%; the weight average molecular weight of the polyaniline was 8000 g / mol, and the molar ratio of polyaniline to hydroxyethyl diamine in the polyaniline aqueous solution was 1:1.

[0121] (3) The casting solution is coated on the surface of the modified polypropylene hollow fiber membrane, and the ratio of the amount of the casting solution in mL to the amount of the modified polypropylene hollow fiber membrane in g is 0.6:1, and then dried in an environment with a relative humidity of 50% and a temperature of 42°C for 24 hours to form a selective separation layer on the surface of the modified polypropylene hollow fiber membrane, thereby obtaining a composite hollow fiber membrane S5.

[0122] In the selective separation layer, the content of polyaniline is 90 wt%, and the content of hydroxyethyl diamine is 10 wt%.

[0123] Example 6

[0124] (1) 80 parts by weight of polyethylene (weight average molecular weight of 5 x 10 6 g / mol, density of 0.97 g / cm 3 ), 19 parts by weight of an amphiphilic polymer (polyurethane-polyester copolymer, weight average molecular weight of 1.5 x 10 4 g / mol, weight ratio of polyurethane and polyester of 50:50), and 1 part by weight of nanoparticles (nano titanium oxide, average particle size of 85 nm) are melt blended at 320°C for 50 minutes in a nitrogen atmosphere, and the obtained blend is extruded by a twin screw extruder at a temperature of 240°C and a rotation speed of 750 rpm, and the obtained particles are metered by a metering pump and then enter the spinneret of a melt spinning machine to perform melt spinning with nitrogen gas at 0.15 MPa as a core liquid, and the obtained nascent fiber is drawn by a five-roller draw machine at a draw ratio of 3000 times to form pores, and then heat treated at 150°C for 120 seconds to obtain a modified polyethylene hollow fiber membrane;

[0125] Based on the total weight of the modified polyethylene hollow fiber membrane, the content of polyethylene is 80 wt%, the content of the amphiphilic polymer is 20 wt% (the content of polyurethane is 9.5 wt%, and the content of polyester is 9.5 wt%), and the content of nanoparticles is 1 wt%.

[0126] (2) A polyvinylamine aqueous solution with a concentration of 4 wt% is mixed with urethane to obtain a casting solution with a concentration of 6 wt%; wherein the weight average molecular weight of the polyvinylamine is 8000 g / mol, and the molar ratio of polyvinylamine to urethane in the polyvinylamine solution is 1:1;

[0127] (3) The casting solution is coated on the surface of the modified polyethylene hollow fiber membrane, and the ratio of the amount of the casting solution in mL to the amount of the modified polyethylene hollow fiber membrane in g is 0.3:1, and then dried in an environment with a relative humidity of 60% and a temperature of 45°C for 24 hours to form a selective separation layer on the surface of the modified polypropylene hollow fiber membrane, thereby obtaining a composite hollow fiber membrane S6.

[0128] The content of the polyvinylamine in the selective separation layer is 65 wt%, and the content of the urethane is 35 wt%.

[0129] Example 7

[0130] (1) 85 parts by weight of polypropylene (weight average molecular weight: 1 x 10 6 g / mol, density: 0.94 g / cm 3 ), 14 parts by weight of an amphiphilic polymer (hydroxyl-terminated butyl polyoxyethylene-polyoxypropylene copolyether, weight average molecular weight: 1.5 x 10 4 g / mol, weight ratio of polyoxyethylene to polyoxypropylene: 50:50), and 1 part by weight of nanoparticles (nano-silica, average particle size: 48 nm) were melt-blended at 270°C for 80 min under a nitrogen atmosphere. The obtained blend was extruded by a twin-screw extruder at a temperature of 220°C and a rotation speed of 500 rpm. The obtained pellets were metered by a metering pump and then introduced into a spinneret of a melt spinning machine. The obtained nascent fibers were drawn by a five-roller draw machine at a draw ratio of 2300 times and then heat-treated at 130°C for 360 s to obtain a modified polypropylene hollow fiber membrane.

[0131] The content of the polypropylene in the modified polypropylene hollow fiber membrane was 85 wt%, the content of the amphiphilic polymer was 14 wt% (the content of the polyoxyethylene was 7 wt% and the content of the polyoxypropylene was 7 wt%), and the content of the nanoparticles was 1 wt%.

[0132] (2) A polyethyleneimine aqueous solution with a concentration of 3 wt% was mixed with piperazine to obtain a casting solution with a concentration of 5.8 wt%. The weight average molecular weight of the polyethyleneimine was 8000 g / mol, and the molar ratio of the polyethyleneimine to the piperazine in the polyethyleneimine solution was 1:1.

[0133] (3) The above casting solution was coated on the surface of the modified polypropylene hollow fiber membrane. The ratio of the amount of the casting solution (in mL) to the amount of the modified polypropylene hollow fiber membrane (in g) was 0.25:1. The modified polypropylene hollow fiber membrane was dried in an environment with a relative humidity of 40% and a temperature of 32°C for 24 h to form a selective separation layer on the surface of the modified polypropylene hollow fiber membrane, thereby obtaining a composite hollow fiber membrane S7.

[0134] The content of the polyethyleneimine in the selective separation layer was 73 wt%, and the content of the piperazine was 27 wt%.

[0135] Example 8

[0136] (1) 68 parts by weight of polybutadiene (weight average molecular weight: 8 x 104 g / mol, density 0.96 g / cm 3 ), 30 parts by weight of an amphiphilic polymer (polyacrylic acid-poly carbonate copolymer, weight average molecular weight 1.8 x 10 4 g / mol, weight ratio of polyacrylic acid and polycarbonate 20:80), 2 parts by weight of nanoparticles (nano-alumina, average particle size 12 nm) were melt blended at 270°C for 80 min, the obtained blend was extruded by a twin-screw extruder, the temperature of the twin-screw extruder was 200°C, the rotation speed was 450 rpm, the obtained particles were metered by a metering pump and then entered the spinneret of a melt spinning machine, melt spinning was performed with 0.23 MPa nitrogen as the core liquid, the obtained nascent fiber was drawn by a five-roller draw machine at a draw ratio of 2500 times, and heat treatment was performed at 140°C for 300 s to obtain a modified polybutadiene hollow fiber membrane;

[0137] The content of polybutadiene was 68 wt%, the content of the amphiphilic polymer was 30 wt% (the content of polyacrylic acid was 6 wt%, and the content of polycarbonate was 24 wt%), and the content of nanoparticles was 2 wt%, based on the total weight of the modified polybutadiene hollow fiber membrane.

[0138] (2) A polyacrylamide aqueous solution with a concentration of 4 wt% and ethylenediamine were mixed to obtain a casting solution with a concentration of 6.9 wt%; wherein the weight average molecular weight of the polyacrylamide was 1500 g / mol, and the molar ratio of polyethyleneimine to ethylenediamine in the polyacrylamide aqueous solution was 1:1.

[0139] (3) The above casting solution was coated on the surface of the modified polybutadiene hollow fiber membrane, and then the use ratio of the casting solution in mL to the modified polybutadiene hollow fiber membrane in g was 0.3:1, and the modified polybutadiene hollow fiber membrane was dried in an environment with a relative humidity of 47% and a temperature of 40°C for 18 h to form a selective separation layer on the surface of the modified polybutadiene hollow fiber membrane, thereby obtaining a composite hollow fiber membrane S8.

[0140] The content of polyacrylamide in the selective separation layer was 60 wt%, and the content of ethylenediamine was 10 wt%.

[0141] Example 9

[0142] According to the method of Example 3, except that in step (1), melt spinning was performed with 0.25 MPa air as the core liquid instead of 0.25 MPa nitrogen as the core liquid, and the remaining steps were the same, thereby obtaining a composite hollow fiber membrane S9.

[0143] Example 10

[0144] The method of Example 3 is the same except that in step (3), drying in an environment with a relative humidity of 45% and a temperature of 38°C for 20 hours is replaced by drying in an environment with a relative humidity of 10% and a temperature of 50°C for 20 hours. The rest of the steps are the same, and the composite hollow fiber membrane S10 is obtained.

[0145] Comparative Example 1

[0146] The method is the same as in Example 3, except that in step (1),

[0147] 75 parts by weight of polybutadiene (weight average molecular weight of 2×10) 6 g / mol, density 0.98 g / cm³ 3 ), 22 parts by weight of the amphiphilic polymer (polyvinyl alcohol-polycarbonate copolymer, weight average molecular weight of 2×10⁻⁶). 4 g / mol, polyvinyl alcohol and polycarbonate in a weight ratio of 40:60) and 3 parts by weight of nanoparticles (nano barium titanate, average particle size of 50 nm) were replaced with

[0148] 60 parts by weight of polybutadiene (weight average molecular weight of 2 × 10⁻⁶) 6 g / mol, density 0.98 g / cm³ 3 ), 36 parts by weight of amphiphilic polymer (polyvinyl alcohol-polycarbonate copolymer, weight average molecular weight of 2×10), 4 The composite hollow fiber membrane DS1 was obtained by adding g / mol of polyvinyl alcohol and polycarbonate in a weight ratio of 40:60 and 4 parts by weight of nanoparticles (nano barium titanate, with an average particle size of 50 nm), and the remaining steps were the same.

[0149] Comparative Example 2

[0150] The method of Example 3 is the same, except that in step (1), 3 parts by weight of nanoparticles (nano barium titanate with an average particle size of 50 nm) are not added, and the rest of the steps are the same to obtain the composite hollow fiber membrane DS2.

[0151] Comparative Example 3

[0152] The method of Example 3 is different except that in step (1), the melting and blending at 300°C for 80 min is replaced with mixing at 250°C for 80 min, and the other steps are the same, to obtain the composite hollow fiber membrane DS3.

[0153] Table 1

[0154]

[0155] Note: * refers to the thickness ratio of the modified poly(C2-C4) olefin hollow fiber membrane (wall thickness) to the selective separation layer.

[0156] From the data in Table 1, the composite hollow fiber membrane provided by the present application has the characteristics of high porosity, thin selective separation layer, high packing density and good pressure resistance.

[0157] Test Example

[0158] The composite hollow fiber membranes (S1-S10 and DS1-DS3) prepared from Examples 1-10 and Comparative Examples 1-3 were subjected to permeation performance test, and the composite hollow fiber membranes (S1-S10 and D1-D3) were assembled into membrane modules P1-P10 and DP1-DP3, respectively.

[0159] (1) The CO2 / H2 mixed gas with a volume ratio of 40:60 was introduced into the membrane modules (P1-P10 and DP1-DP3) for separation, and the permeation performance parameters of CO2 and the separation factor parameters of CO2 / H2 were measured and listed in Table 2;

[0160] (2) The H2S / H2 mixed gas with a volume ratio of 10:90 was introduced into the membrane modules (P1-P10 and DP1-DP3) for separation, and the permeation performance parameters of H2S and the separation factor parameters of H2S / H2 were measured and listed in Table 3.

[0161] Table 2

[0162] Permeability of CO2, cm 3 (STP) / (cm 2 ·s·cm Hg) Separation factor of CO2 / H2 Example 1 300 x 10 -6 ]]> 20 Example 2 500 x 10 -6 ]] 25 Example 3 600 x 10 -6 ]] 30 Example 4 400 x 10 -6 ]] 23 Example 5 700 x 10 -6 ]] 35 Example 6 800 x 10 -6 ]] 40 Example 7 440 x 10 -6 ]] 23.8 Example 8 580 x 10 -6 ]] 28 Example 9 630 x 10 -6 ]]> 32 Example 10 462 x 10 -6 ]] 24 Comparative Example 1 110 x 10 -6 ]] 3 Comparative Example 2 89 x 10 -6 ]] 5 Comparative Example 3 109 x 10 -6 ]] 4

[0163] Table 3

[0164]

[0165]

[0166] From the data in Tables 2-3, it can be seen that, compared with Comparative Examples 1-3, the membrane module prepared from the composite hollow fiber membrane provided by the present application can effectively improve the permeation performance parameters and separation factor of the acid gas when used for selective removal of the acid gas, that is, effectively improve the removal efficiency of the acid gas.

[0167] The above describes the preferred embodiments of the present application in detail, but the present application is not limited thereto. Within the technical concept of the present application, various simple modifications can be made to the technical solutions of the present application, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be considered as disclosed by the present application and fall within the protection scope of the present application.

Claims

1. A composite hollow fiber membrane, characterized by, The composite hollow fiber membrane comprises: a modified poly-C2-C4 olefin hollow fiber membrane and a selective separation layer loaded on the modified poly-C2-C4 olefin hollow fiber membrane; the modified poly-C2-C4 olefin hollow fiber membrane is prepared from a composition I of poly-C2-C4 olefin, amphiphilic polymer and nanoparticles; wherein, based on the total weight of the modified poly-C2-C4 olefin hollow fiber membrane, the content of the poly-C2-C4 olefin is 65-85 wt%, the content of the amphiphilic polymer is 6-35 wt%, and the content of the nanoparticles is 1-3 wt%; in the amphiphilic polymer, the weight ratio of the hydrophilic group to the hydrophobic group is 20-50: 50-80; wherein, the selective separation layer is prepared from a composition II of amine-based polymer and nitrogen-containing small organic molecules; based on the total weight of the selective separation layer, the content of the amine-based polymer is 60-90 wt%, and the content of the nitrogen-containing small organic molecules is 10-40 wt%.

2. The composite hollow fiber membrane according to claim 1, wherein, based on the total weight of the modified poly-C2-C4 olefin hollow fiber membrane, the content of the poly-C2-C4 olefin is 65-80 wt%, the content of the amphiphilic polymer is 19-32 wt%, and the content of the nanoparticles is 1-3 wt%; and / or the weight average molecular weight of the poly-C2-C4-olefin is 1 x 105 4 - 5 x 105 6 g / mol; the density is 0.9 - 0.98 g / cm 3 .

3. The composite hollow fiber membrane according to claim 2, wherein, The weight average molecular weight of the poly-C2-C4-olefin is 8 x 10 4 -3 x 10 6 g / mol; the density is 0.92-0.95 g / cm 3 g / mol; the density is 0.92-0.95 g / cm 4. The composite hollow fiber membrane according to claim 1, wherein, in the amphiphilic polymer, the weight ratio of the hydrophilic group to the hydrophobic group is 25-35: 65-75; and / or, in the amphiphilic polymer, the hydrophilic group is selected from at least one of polyoxyethylene, polyacrylic acid, polypropylene amide, polyvinyl alcohol, polyamide and polyurethane; the hydrophobic group is selected from at least one of polyoxypropylene, polyamide, polycarbonate, polyacrylonitrile and polyester; and / or the weight average molecular weight of the amphiphilic polymer is 1 x 10 3 -2 x 10 4 g / mol; and / or, the average particle size of the nanoparticles is 5-100 nm; and / or, the nanoparticles are selected from at least one of nano-silicon dioxide, nano-aluminum oxide, nano-titanium oxide, nano-barium titanate and nano-strontium titanate.

5. The composite hollow fiber membrane according to claim 4, wherein, The weight average molecular weight of the amphiphilic polymer is 5 x 10 3 -1 x 10 4 g / mol; and / or, the average particle size of the nanoparticles is 20-60 nm.

6. The composite hollow fiber membrane according to claim 1, wherein, based on the total weight of the selective separation layer, the content of the amine-based polymer is 70-80 wt%, and the content of the nitrogen-containing small organic molecules is 20-30 wt%; and / or, in the composition II, the molar ratio of the amine-based polymer to the nitrogen-containing small organic molecules is 1: 1-5; and / or, the weight average molecular weight of the amine-based polymer is 1500-8000 g / mol; and / or, the amine-based polymer is selected from at least one of polyacrylamide, polyvinylamine, polyethyleneimine and polyaniline; and / or, the nitrogen-containing small organic molecules are selected from at least one of ethylenediamine, piperazine, diethanolamine, hydroxyethyl diamine and urethane.

7. The composite hollow fiber membrane according to claim 6, wherein, in the composition II, the molar ratio of the amine-based polymer to the nitrogen-containing small organic molecules is 1: 1-3; and / or, the weight average molecular weight of the amine-based polymer is 2000-4000 g / mol.

8. The composite hollow fiber membrane according to any one of claims 1-7, wherein, The packing density of the composite hollow fiber membrane is 1500-3000 m 2 / m 3 ; the pressure resistance is 10-15 MPa; and / or, the outer diameter of the composite hollow fiber membrane is 1-5 mm; the central hole diameter is 0.2-4 mm; the thickness is 400-1000 µm; And / or, the average pore size of the modified poly-C2-C4 olefin hollow fiber membrane is 1-5 mm; the porosity is 60-90%; And / or, the average thickness of the selection separation layer is 100-900 µm; And / or, the thickness ratio of the modified poly-C2-C4 olefin hollow fiber membrane and the selection separation layer is 1-4:

1.

9. The composite hollow fiber membrane according to claim 8, wherein, The packing density of the composite hollow fiber membrane is 1800-2100 m 2 / m 3 ; the pressure resistance is 11-13 MPa; And / or, the outer diameter of the composite hollow fiber membrane is 2-4 mm; the center hole diameter is 0.6-2 mm; the thickness is 600-800 µm; And / or, the average pore size of the modified poly-C2-C4 olefin hollow fiber membrane is 2-3 mm; the porosity is 65-75%; And / or, the average thickness of the selection separation layer is 200-800 µm; And / or, the thickness ratio of the modified poly-C2-C4 olefin hollow fiber membrane and the selection separation layer is 2-3:

1.

10. A method for producing a composite hollow fiber membrane, characterized by, The method comprises the following steps: (1) In the presence of inert gas, the composition I of poly-C2-C4 olefin, amphiphilic polymer and nanoparticles is sequentially melt blended, double screw extruded, melt spun, drawn, and heat treated to obtain a modified poly-C2-C4 olefin hollow fiber membrane; in the amphiphilic polymer, the weight ratio of hydrophilic group and hydrophobic group is 20-50:50-80; (2) The casting solution containing composition II is coated on the surface of the modified poly-C2-C4 olefin hollow fiber membrane, and then dried to form a selection separation layer on the surface of the modified poly-C2-C4 olefin hollow fiber membrane to obtain a composite hollow fiber membrane; Wherein, in the composition I, the weight ratio of poly-C2-C4 olefin, amphiphilic polymer and nanoparticles is 65-85:6-35:1-3; Wherein, the composition II is composed of amine-based polymer and nitrogen-containing organic small molecule, and the mass ratio of amine-based polymer and nitrogen-containing organic small molecule is 60-90:10-40.

11. The production method according to claim 10, wherein In step (1), the melting blending conditions include: temperature 250-350℃, time 30-180 min; And / or, in step (1), the double screw extrusion conditions include: temperature 180-240℃, rotation speed 300-900 rpm; And / or, in step (1), the core liquid of the spinning plate in the melt spinning is nitrogen, and the pressure of nitrogen is 0.15-0.35 MPa; And / or, in step (1), the draw ratio is 500-3000; And / or, in step (1), the heat treatment conditions include: temperature 100-160℃; time 1-10 min.

12. The method of making according to claim 11, wherein, In step (1), the melting blending conditions include: temperature 270-320℃, time 50-90 min; And / or, in step (1), the draw ratio is 1500-2500; And / or, in step (1), the heat treatment conditions include: temperature 120-150℃; time 2-3 min.

13. The production method according to claim 10, wherein, In the casting solution, the concentration of the composition II is 0.5-9wt%; And / or, in the composition II, the molar ratio of the amine-based polymer and the nitrogen-containing organic small molecule is 1:1-5; And / or, the casting solution is mixed by an aqueous solution containing the amine-based polymer and the nitrogen-containing small organic molecule; And / or, the ratio of the use amount of the casting solution in mL to the modified poly-C2-C4 olefin hollow fiber membrane in g is 0.1-0.6:1; And / or, in step (2), the drying treatment conditions include: relative humidity of 20-80%; temperature of 15-60℃; time of 5-30h.

14. The production method according to claim 13, wherein The concentration of the composition II in the casting solution is 1-5wt%; And / or, in the composition II, the molar ratio of the amine-based polymer to the nitrogen-containing small organic molecule is 1:1-3; And / or, the ratio of the use amount of the casting solution in mL to the modified poly-C2-C4 olefin hollow fiber membrane in g is 0.2-0.4:1; And / or, in step (2), the drying treatment conditions include: relative humidity of 35-60%; temperature of 25-45℃; time of 8-24h. The membrane module contains the composite hollow fiber membrane according to any one of claims 1-9, or the composite hollow fiber membrane prepared by the method according to any one of claims 10-14.

15. A membrane module, characterized by The method comprises: passing a mixed gas containing acid gas into the membrane module according to claim 15 for separation.

16. A method of separating acid gases, characterized by, The volume content of acid gas in the mixed gas is 1-50vol%; 17. The method of claim 16, wherein, And / or, the acid gas is at least one selected from CO2, H2S and SO2. ​

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