KR20180007394A - Hollow fiber membrane having carbon molecular sieve supported by inorganic support and a method for gas separation using the same - Google Patents

Abstract

The present invention relates to: a carbon molecular sieve hollow fiber membrane reinforced by an inorganic support; a manufacturing method thereof; and a method of separating a mixture of olefin/paraffin or a mixture of nitrogen/hydrogen by using the carbon molecular sieve hollow fiber membrane as a separation membrane. The composite hollow fiber membrane according to the present invention has an outer diameter of 0.1-4 mm, an inner diameter of 0.05-3 mm, and a thickness of 0.01-2 mm and includes: an inorganic hollow fiber support which is manufactured by using first inorganic particles having a first particle size and has an outer diameter of 4 mm or less having a first pore size; a first layer in which second inorganic particles having a second particle size smaller than the first particle size fill pores on the surface of inorganic hollow fiber support by filling the pores of the surface of the inorganic hollow fiber support with sol containing the second inorganic particles or precursors thereof; and a second layer which contains the carbon molecular sieve by performing pyrolysis after coating the first layer with first inorganic polymer-containing solution. The present invention enables high packing density and easy scale-up by modularity.

Description

Technical Field [0001] The present invention relates to a carbon fiber self-hollow fiber membrane reinforced by an inorganic support, and a method of separating a gas using the same,

The present invention relates to a carbon molecular sieve hollow fiber membrane reinforced by an inorganic support; A method for producing the same; And a method for separating a mixture of olefin / paraffin or a mixture of nitrogen and hydrogen using the carbon molecular sieve hollow fiber membrane as a separator.

Separation and purification of olefins / paraffins in petrochemical processes generally consists of distillation processes. The distillation process utilizes the difference in boiling point between the two gases. Propylene / propane separations with similar boiling points require more than 200 distillation stages, thus consuming a lot of energy. On the contrary, since the membrane technology does not depend on the thermodynamic equilibrium, propylene / propane can be separated with high energy efficiency, which is expected to replace the conventional liquid distillation method.

Membrane technology is a technique for separating a specific component (one component or multiple components) from a mixture of two or more components using a physical boundary layer. Currently, membrane technology has been widely applied in a wide range of applications ranging from simple laboratory scale to large-scale industry, in accordance with the social demand for the protection of the global environment, including the production of high-purity, highly functional materials and industrial wastewater treatment. Since the separation membrane process is a physical and mechanical separation operation that does not require a phase change, energy can be saved up to about 70% to 80% or more as compared with a conventional energy-less non-specific process, and the separation principle and process are relatively simple Thereby simplifying the configuration and installation of the apparatus and reducing the space occupied by the apparatus, thereby reducing the facility cost.

The membrane can be divided into various materials according to the size of the material and the micropores. The synthetic membrane can be classified into an organic membrane and an inorganic membrane. The organic membrane is mostly composed of a polymer and is called a polymer membrane. The inorganic membrane is made of ceramics, glass, It is a membrane used for this material.

The polymer membrane is difficult to exceed the upper-bound trade-off which shows the limit of the permeability and the selectivity, and has problems such as plasticization and long-term stability. In recent years, porous inorganic membranes such as ZIF-8, hybrid silica, and carbon molecular sieve (CMS) membranes have been developed to overcome the above-mentioned problems and have thermal and chemical stability and overcome upper bound.

CMS membranes are prepared by pyrolysis or carbonization of polymer membranes in a vacuum or oxygen free environment. The performance of CMS membranes with slit-like micropores depends on the polymer precursor, pyrolysis conditions, and the like. The permeability of the membranes is a major factor in determining the productivity, especially in the separation and purification process, which can be improved by controlling the thickness of the selective layer.

An object of the present invention is to provide an asymmetric composite membrane in which a carbon molecular sieve separating membrane is formed on an inorganic support in the form of a hollow fiber membrane so as to facilitate the face-up by high packing density and modularization.

Another object of the present invention is to provide a method for producing an asymmetric or composite membrane in which a thin and uniform carbon molecular sieve separating membrane is formed for separation of a substance having a similar molecular size in an inorganic support of hollow fiber membrane type.

A first aspect of the present invention is a hollow fiber composite membrane having an outer diameter of 0.1 mm to 4 mm, an inner diameter of 0.05 mm to 3 mm and a thickness of 0.01 mm to 2 mm, An inorganic hollow support having an outer diameter of 4 mm or less and having a first pore size, prepared using the first inorganic particles; A sol containing a second inorganic particle or a precursor thereof is filled in the pores on the surface of the inorganic hollow fiber support to form a second inorganic particle having a second particle size smaller than the first particle size on the inorganic hollow fiber support surface A first layer filling the pores of the first layer; And a second layer containing a carbon molecular sieve formed by coating a first organic polymer-containing solution on the first layer and then pyrolysis.

The second aspect of the present invention is a method for producing the composite hollow fiber membrane of the first aspect, wherein the inorganic hollow fiber support having an outer diameter of 4 mm or less and having a first pore size, which is produced by using the first inorganic particles, A first step of coating with a sol containing a particle or a precursor thereof; A second step of gelling a sol filled in the pores of the surface of the inorganic hollow fiber support with a gel of a network formed by connecting the second inorganic particles; A third step in which a second inorganic particle having a second particle size smaller than the first particle size is formed by drying or heat treatment to form a first layer filled with pores on the surface of the inorganic hollow fiber support; A fourth step of coating the first organic polymer-containing solution on the first layer; And a fifth step of forming a second layer containing a carbon molecular sieve by pyrolysis of the coated first organic polymer.

A third aspect of the present invention provides a membrane module comprising the composite hollow fiber membranes of the first aspect.

A fourth aspect of the present invention provides a method for separating olefins and paraffins of the same carbon number using the membrane module of the third aspect.

A fifth aspect of the present invention provides a method for producing a separated olefin or a separated paraffin comprising separating an olefin and a paraffin-containing gas using the separation membrane module of the third aspect.

A sixth aspect of the present invention provides a method for separating nitrogen and hydrogen using the membrane module of the third aspect.

Hereinafter, the present invention will be described in detail.

In the present specification, the pore size and the particle size are preferably an average pore size and an average particle size.

CMS membranes can have pore channels of two sizes: 4 ~ 6 Å micropores (Ultramicro pore) and 6 ~ 20 Å micropores. The molecular sieve property is realized in the pore of 4 ~ 6 Å micro or less, and it is possible to have high permeability and selectivity because it spreads rapidly in a relatively wide micro pore channel. In particular, CMS membranes have very good properties for separating very small molecules of similar size. That is, it is very important to control the microstructure and porosity of the CMS membrane.

In order to prepare a CMS membrane as a hollow fiber membrane by a high filling density and modularization, a polymer solution is coated on an inorganic support of a hollow fiber type having an outer diameter of 4 mm or less and pyrolyzed the polymer to form a carbon powder Thereby providing an asymmetric composite membrane having a separation membrane.

In this case, in order to form a thin and uniform carbon molecular sieve separating membrane for separating a material having a similar molecular size on a hollow inorganic support, before coating a polymer solution for forming a carbon molecular sieve separator on a hollow inorganic support, A sol containing inorganic particles or a precursor thereof is filled in the pores on the surface of the inorganic hollow fiber support, and then an inorganic layer is formed by drying and / or heat treatment to form an intermediate layer filling the pores of the inorganic hollow fiber support Another feature is letting.

Therefore, the composite hollow fiber membrane according to the present invention has an outer diameter of 0.1 mm to 4 mm, an inner diameter of 0.05 mm to 3 mm, a thickness of 0.01 mm to 2 mm,

An inorganic hollow support having an outer diameter of 4 mm or less and having a first pore size, prepared using a first inorganic particle having a first particle size;

A sol containing a second inorganic particle or a precursor thereof is filled in the pores on the surface of the inorganic hollow fiber support to form a second inorganic particle having a second particle size smaller than the first particle size on the inorganic hollow fiber support surface A first layer filling the pores of the first layer; And

And a second layer containing a carbon molecular sieve formed by coating a first organic polymer-containing solution on the first layer and then pyrolysis.

If the outer diameter exceeds 0.4 mm, there may be a problem that the filling density of the hollow fiber is lowered when the hollow fiber membranes are bundled, and when the outer diameter is less than 0.1 mm, the physical strength is low,

Further, one embodiment of the method for producing a composite hollow fiber membrane according to the present invention

A first step of coating an inorganic hollow support having an outer diameter of 4 mm or less and having a first pore size using a first inorganic particle with a sol containing a second inorganic particle or a precursor thereof;

A second step of gelling a sol filled in the pores of the surface of the inorganic hollow fiber support with a gel of a tissue formed by connecting the second inorganic particles;

A third step in which a second inorganic particle having a second particle size smaller than the first particle size is formed by drying or heat treatment to form a first layer filled with pores on the surface of the inorganic hollow fiber support;

A fourth step of coating the first organic polymer-containing solution on the first layer; And

And a fifth step of pyrolysis of the coated first organic polymer to form a second layer containing a carbon molecular sieve.

Non-limiting examples of the first inorganic particle and / or the second inorganic particle may each independently be a (sub) metal, a (sub) metal oxide, a ceramic (e.g., alumina), and in one embodiment, May be? -Alumina, and the second inorganic particle having a second particle size smaller than the first particle size may be? -Alumina.

In one embodiment of the present invention, as shown in Fig. 1 (left-hand diagram), in order to produce a thin CMS separator on an a-alumina support in the form of a hollow fiber, a uniform, defect- . Accordingly, it is possible to provide a composite hollow fiber membrane in which a thin and dense carbon molecular sieve active layer is formed on a high-strength porous alumina hollow fiber support.

When inorganic hollow support is used, it is easy to make the CMS separation membrane large-sized and modularized. In addition, due to the presence of the first layer filling the pores of the inorganic hollow fiber support, the thickness of the second layer containing carbon molecular sieve can be adjusted to 0.1 to 10 mu m.

In order to use the composite hollow fiber membrane of the present invention as a separator, the first pore size of the inorganic support and the second pore size formed by the second inorganic particles may be a pore size capable of permeating the substance to be passed through the composite membrane .

The ceramic hollow support can be produced by an extrusion method or a phase transfer method.

The inorganic hollow support may be formed by hollow fiber forming and sintering the mixture containing the first inorganic particles and the second organic polymer. At this time, the second organic polymer acts as a binder before sintering and can be removed by thermal decomposition during sintering. Thus, the pore size (first pore size) of the inorganic hollow support can be determined by the first particle size of the first inorganic particle. In order to form a high strength hollow support, the size of the first inorganic particles may be 50 nm or more, preferably 0.1 to 10 탆.

The inorganic hollow support can be produced by the method described in Korean Patent Application No. 2015-0191653, which performs a kneading and extruding process using an extruder equipped with a screw and a phase transfer process, which is incorporated herein by reference.

Group IA metals, Group IIA metals, Group IIA metals, Group IVA metals, and oxides of transition metals may be used as the precursor of the first inorganic material in the precursor solution or slurry for forming the inorganic hollow support. For example, , aluminum (Al ₂ O ₃₎ alone use or with aluminum sulfate, aluminum oxide as oxide _{(Al 2 (SO 4) 3} ), silicon dioxide (SiO _2), kaolin nitro _{(Al 2 Si 2 O 5 (} OH) 4) And bentonite may be mixed and used.

Non-limiting examples of the polymeric binder (second polymer) used in the precursor solution or slurry for forming the inorganic hollow support include Polysulfone, Polyethersulfone, Polyacrylate, Polyacrylate But are not limited to, polyacrylonitrile, polysulfide, polyketone, polyetherketone, polyethertherketone, polyimide, polyamide, polyamide-imide Polyamide-imide, polyvinylidene fluoride, polyethylene, polypropylene, polyetherimide, polyvinylchloride, and the like.

The second polymer is preferably added in an amount of from 2 wt% to 8 wt% based on the total weight of the precursor solution or slurry. When it is added in an amount of less than 2% by weight, it is difficult to act as a binder, and when it is added in an amount of more than 8% by weight, viscosity of the solution becomes too large.

In addition to the precursor solution or slurry for forming the inorganic hollow support, a sintering aid such as yttrium oxide (Y ₂ O ₃ ) or magnesium oxide (MgO) and a dispersant such as BYK-190 may be added. The sintering aid enhances the mechanical strength of the hollow fiber membrane by increasing the sintering speed of the hollow fiber membrane, and the dispersing agent serves to uniformly distribute the aluminum precursor in the polar organic solvent.

The precursor solution or slurry for forming the inorganic hollow support may further contain a polar organic solvent, and examples of the polar organic solvent include N-methyl pyrrolidone (NMP), 1-methyl-2-pyrrolidone, Amide, dimethylacetamide, dimethylformaldehyde, dimethylsulfoxide, trimethylphosphate, triethylphosphate and the like.

When the first inorganic particles are used in a micrometer scale to form a high strength hollow support, it is difficult to form a uniform polymer thin layer by permeating into the large pores of the support when the polymer solution for CMS separation membrane is coated. Therefore, in order to reduce the large pores of the high strength hollow support, it is necessary to form an intermediate layer having an average pore size of 50 nm or less. However, if it is less than 10 nm, the gas permeability may be lowered.

In order to form the intermediate layer for filling the pores of the inorganic hollow support surface, the present invention is characterized by filling the pores of the inorganic hollow support surface with a sol containing a second inorganic particle or a precursor thereof.

If the sol filled in the pores on the surface of the inorganic hollow fiber support is dried, the pores on the surface of the inorganic hollow fiber support can be filled with the second inorganic particles. In order to prevent impregnation with the hollow fiber membrane support so as to coat the organic polymer- The second pore size formed by the second inorganic particles can be controlled.

At this time, the particle size of the second inorganic particle, that is, the second particle size, may be 3 nm to 100 nm.

Heat treatment after filling the sol can increase the binding force and control the second pore size formed by the second inorganic particles.

A colloid is a colloid in which fine particles of about 1 to 100 nm are dispersed in a liquid without aggregation or precipitation. In this case, a colloid in which solid particles are dispersed in a liquid is referred to as sol. do. In the membrane, the sol-gel method is often used to make thin and uniform thin films by heating after sol or gel.

Alumina sol can be used to form uniform and defectless? -Alumina on the surface pores of the? -Alumina support. As precursors of γ-alumina, atypical alumina, γ-alumina nanoparticles, aluminum trihydroxide, boehmite and pseudo-boehmite can be used.

The sol for forming the intermediate layer (first layer) may be a water-based sol and / or an alcohol-based sol.

By controlling the physical properties such as the type and volatility of the solvent in the sol, it is possible to form a thin and uniform coating as the second inorganic particles or precursor thereof in the sol are uniformly dispersed.

The content of the second inorganic material may be 0.01 to 5 wt% based on the total weight of the inorganic hollow fiber support prepared using the first inorganic particles. If the amount is more than 5% by weight, the inorganic intermediate layer (first layer) is formed to be very thick, cracks are generated during the sintering process, an unstable intermediate layer is formed, and the coated layer is separated.

In one embodiment, the first step is to dip-coat the inorganic hollow support prepared using the first inorganic particles with a sol containing the second inorganic particles or a precursor thereof.

The immersion coating time is about 1 to 600 seconds, and the ramping rate can be 0.1 to 30 mm / s. By adjusting the immersion speed and / or time, the coating layer thickness and uniformity can be optimized.

If the ramping speed is high, the inorganic intermediate layer becomes thick and a uniform coating layer is difficult to form. If the speed is slow, the inorganic intermediate layer becomes thin, and the coating solution may penetrate into the hollow fiber membrane.

The sol filled in the pores of the inorganic hollow support surface may be gelled with a gel of the formed tissue formed by the second inorganic particles to lower the porosity.

The thickness of the inorganic intermediate layer may be 0.1 占 퐉 to 10 占 퐉. If the thickness of the intermediate layer is too thick, there is a disadvantage that cracks are generated and the gas permeability is greatly reduced. If the thickness is too thin, the coating may not be properly formed and defects may occur.

Non-limiting examples of the first organic polymer used in the first organic polymer-containing solution used for forming the carbon molecular sieve-containing active layer include polyimide (polysulfone, polyethersulfone, Polyphenol, polyacrylate, polyacrylonitrile, polyethertherketone, polyamide, polyvinylidene fluoride, polyetherimide, and the like. Polyvinylchloride, polyphenyloxide, polyfurfuric alcohol, etc. The concentration of the first organic polymer may be 0.001 to 5% by weight.

Non-limiting examples of the solvent usable in the first organic polymer-containing solution include N-methyl-2-pyrrolidone (NMP) or tetrahydrofuran (THF). When THF is used as the solvent, the evaporation of the solvent can occur rapidly and the coating layer can be formed uniformly and thickly.

Changes in temperature and humidity at the time of sol coating in the first step and in coating the solution containing the first organic polymer in the fourth step may have a great influence on the formation of the coating layer. Therefore, it is important to maintain constant temperature and humidity, and the coating can proceed in a constant temperature and humidity chamber.

The humidity is preferably 40% or less. The higher the humidity, the faster the phase transition occurs in the immersion coating and the polymer coating process, the non-uniform coating layer can be formed, and the temperature also affects the viscosity and volatilization rate of the second inorganic substance or its precursor-containing sol and the first organic polymer- . In one embodiment, gamma-alumina and polymer coatings can be conducted using a dip coater.

The solvent and the impurities may be removed from the first organic polymer-containing solution, and the pyrolysis process may be performed to stabilize the separation membrane. In the fifth step, pyrolysis can be carried out at 500 to 800 ° C for 0.1 to 10 hours.

Meanwhile, it may further include a step of sintering between the third step and the fourth step.

The sintering may be performed at 300 to 800 ° C. If the temperature is lower than 300 ° C, the properties of the hollow fiber membrane may be deteriorated. If the temperature exceeds 800 ° C, the phase transition of the particles may occur, resulting in cracks or deformation of the pore structure.

In one embodiment, the pyrolysis and sintering may be performed in a box sintered furnace or a tubular furnace as non-limiting examples.

During the carbonization of the first organic polymer by pyrolysis, if a small amount of oxygen is also introduced into the sintering furnace, oxidation may occur and a non-uniform carbon layer may be formed with defects on the surface of the separator. In one embodiment, the sintering furnace may be constructed to block external oxygen inflow while continuously flowing ultrahigh purity He (99.9999%). During the pyrolysis process, He is supplied as a carrier gas at a flow rate of about 250 cc / min, and pyrolysis process can be performed after sufficiently flowing He. Also, in order to prevent the temperature gradient due to heat loss from occurring due to the characteristics of the sintering furnace (tube-type furnace), both ends of the separation membrane sample can be fixed with a ceramic refractory.

According to the present invention, a composite hollow fiber membrane in which a carbon molecular sieve is formed on a high-strength inorganic hollow fiber support can form bundles to provide a separation membrane module (FIG. 1, right side view). Thus, the separation membrane module can be used to separate a mixture of olefins of the same carbon number with paraffins (e.g. propylene / propane), nitrogen and hydrogen, nitrogen and propylene.

Also, the separation membrane module according to the present invention can be applied to a system such as a liquid energy carrier, production of chemical substances, oxygen generation, low emission of carbon dioxide, hydrogen-related technology, and carbon compound capture.

In one embodiment of the present invention, as shown in Fig. 1 (left-hand diagram), in order to produce a thin CMS separator on an a-alumina support in the form of a hollow fiber, a uniform, defect- . Accordingly, it is possible to provide a composite hollow fiber membrane in which a thin and dense carbon molecular sieve active layer is formed on a high-strength porous alumina hollow fiber support.

When inorganic hollow support is used, it is easy to make the CMS separation membrane large-sized and modularized. In addition, due to the presence of the first layer filling the pores of the inorganic hollow fiber support, the thickness of the second layer containing carbon molecular sieve can be adjusted to 0.1 to 10 mu m.

In order to use the composite hollow fiber membrane of the present invention as a separator, the first pore size of the inorganic support and the second pore size formed by the second inorganic particles may be a pore size capable of permeating the substance to be passed through the composite membrane .

The ceramic hollow support can be produced by an extrusion method or a phase transfer method.

The inorganic hollow support may be formed by hollow fiber forming and sintering the mixture containing the first inorganic particles and the second organic polymer. At this time, the second organic polymer acts as a binder before sintering and can be removed by thermal decomposition during sintering. Thus, the pore size (first pore size) of the inorganic hollow support can be determined by the first particle size of the first inorganic particle. In order to form a high strength hollow support, the size of the first inorganic particles may be 50 nm or more, preferably 0.1 to 10 탆.

The inorganic hollow support can be produced by the method described in Korean Patent Application No. 2015-0191653, which performs a kneading and extruding process using an extruder equipped with a screw and a phase transfer process, which is incorporated herein by reference.

Group IA metals, Group IIA metals, Group IIA metals, Group IVA metals, and oxides of transition metals may be used as the precursor of the first inorganic material in the precursor solution or slurry for forming the inorganic hollow support. For example, , aluminum (Al ₂ O ₃₎ alone use or with aluminum sulfate, aluminum oxide as oxide _{(Al 2 (SO 4) 3} ), silicon dioxide (SiO _2), kaolin nitro _{(Al 2 Si 2 O 5 (} OH) 4) And bentonite may be mixed and used.

Non-limiting examples of the polymeric binder (second polymer) used in the precursor solution or slurry for forming the inorganic hollow support include Polysulfone, Polyethersulfone, Polyacrylate, Polyacrylate But are not limited to, polyacrylonitrile, polysulfide, polyketone, polyetherketone, polyethertherketone, polyimide, polyamide, polyamide-imide Polyamide-imide, polyvinylidene fluoride, polyethylene, polypropylene, polyetherimide, polyvinylchloride, and the like.

The second polymer is preferably added in an amount of from 2 wt% to 8 wt% based on the total weight of the precursor solution or slurry. When it is added in an amount of less than 2% by weight, it is difficult to act as a binder, and when it is added in an amount of more than 8% by weight, viscosity of the solution becomes too large.

In addition to the precursor solution or slurry for forming the inorganic hollow support, a sintering aid such as yttrium oxide (Y ₂ O ₃ ) or magnesium oxide (MgO) and a dispersant such as BYK-190 may be added. The sintering aid enhances the mechanical strength of the hollow fiber membrane by increasing the sintering speed of the hollow fiber membrane, and the dispersing agent serves to uniformly distribute the aluminum precursor in the polar organic solvent.

The precursor solution or slurry for forming the inorganic hollow support may further contain a polar organic solvent, and examples of the polar organic solvent include N-methyl pyrrolidone (NMP), 1-methyl-2-pyrrolidone, Amide, dimethylacetamide, dimethylformaldehyde, dimethylsulfoxide, trimethylphosphate, triethylphosphate and the like.

When the first inorganic particles are used in a micrometer scale to form a high strength hollow support, it is difficult to form a uniform polymer thin layer by permeating into the large pores of the support when the polymer solution for CMS separation membrane is coated. Therefore, in order to reduce the large pores of the high strength hollow support, it is necessary to form an intermediate layer having an average pore size of 50 nm or less. However, if it is less than 10 nm, the gas permeability may be lowered.

In order to form the intermediate layer for filling the pores of the inorganic hollow support surface, the present invention is characterized by filling the pores of the inorganic hollow support surface with a sol containing a second inorganic particle or a precursor thereof.

If the sol filled in the pores on the surface of the inorganic hollow fiber support is dried, the pores on the surface of the inorganic hollow fiber support can be filled with the second inorganic particles. In order to prevent impregnation with the hollow fiber membrane support so as to coat the organic polymer- The second pore size formed by the second inorganic particles can be controlled. At this time, the particle size of the second inorganic particle, that is, the second particle size, may be 3 nm to 100 nm.

Heat treatment after filling the sol can increase the binding force and control the second pore size formed by the second inorganic particles.

A colloid is a colloid in which fine particles of about 1 to 100 nm are dispersed in a liquid without aggregation or precipitation. In this case, a colloid in which solid particles are dispersed in a liquid is referred to as sol. do. In the membrane, the sol-gel method is often used to make thin and uniform thin films by heating after sol or gel.

Alumina sol can be used to form uniform and defectless? -Alumina on the surface pores of the? -Alumina support. As precursors of γ-alumina, atypical alumina, γ-alumina nanoparticles, aluminum trihydroxide, boehmite and pseudo-boehmite can be used.

The sol for forming the intermediate layer (first layer) may be a water-based sol and / or an alcohol-based sol.

By controlling the physical properties such as the type and volatility of the solvent in the sol, it is possible to form a thin and uniform coating as the second inorganic particles or precursor thereof in the sol are uniformly dispersed.

The content of the second inorganic material may be 0.01 to 5 wt% based on the total weight of the inorganic hollow fiber support prepared using the first inorganic particles. If the amount is more than 5% by weight, the inorganic intermediate layer (first layer) is formed to be very thick, cracks are generated during the sintering process, an unstable intermediate layer is formed, and the coated layer is separated.

In one embodiment, the first step is to dip-coat the inorganic hollow support prepared using the first inorganic particles with a sol containing the second inorganic particles or a precursor thereof.

The immersion coating time is about 1 to 600 seconds, and the ramping rate can be 0.1 to 30 mm / s. By adjusting the immersion speed and / or time, the coating layer thickness and uniformity can be optimized.

If the ramping speed is high, the inorganic intermediate layer becomes thick and a uniform coating layer is difficult to form. If the speed is slow, the inorganic intermediate layer becomes thin, and the coating solution may penetrate into the hollow fiber membrane.

The sol filled in the pores of the inorganic hollow support surface may be gelled with a gel of the formed tissue formed by the second inorganic particles to lower the porosity.

The thickness of the inorganic intermediate layer may be 0.1 占 퐉 to 10 占 퐉. If the thickness of the intermediate layer is too thick, there is a disadvantage that cracks are generated and the gas permeability is greatly reduced. If the thickness is too thin, the coating may not be properly formed and defects may occur.

Non-limiting examples of the first organic polymer used in the first organic polymer-containing solution used for forming the carbon molecular sieve-containing active layer include polyimide (polysulfone, polyethersulfone, Polyphenol, polyacrylate, polyacrylonitrile, polyethertherketone, polyamide, polyvinylidene fluoride, polyetherimide, and the like. Polyvinylchloride, polyphenyloxide, polyfurfuric alcohol, etc. The concentration of the first organic polymer may be 0.001 to 5% by weight.

Non-limiting examples of the solvent usable in the first organic polymer-containing solution include N-methyl-2-pyrrolidone (NMP) or tetrahydrofuran (THF). When THF is used as the solvent, the evaporation of the solvent can occur rapidly and the coating layer can be formed uniformly and thickly.

Changes in temperature and humidity at the time of sol coating in the first step and in coating the solution containing the first organic polymer in the fourth step may have a great influence on the formation of the coating layer. Therefore, it is important to maintain constant temperature and humidity, and the coating can proceed in a constant temperature and humidity chamber.

The humidity is preferably 40% or less. The higher the humidity, the faster the phase transition occurs in the immersion coating and the polymer coating process, the non-uniform coating layer can be formed, and the temperature also affects the viscosity and volatilization rate of the second inorganic substance or its precursor-containing sol and the first organic polymer- . In one embodiment, gamma-alumina and polymer coatings can be conducted using a dip coater.

The solvent and the impurities may be removed from the first organic polymer-containing solution, and the pyrolysis process may be performed to stabilize the separation membrane. In the fifth step, pyrolysis can be carried out at 500 to 800 ° C for 0.1 to 10 hours.

Meanwhile, it may further include a step of sintering between the third step and the fourth step.

The sintering may be performed at 300 to 800 ° C. If the temperature is lower than 300 ° C, the properties of the hollow fiber membrane may be deteriorated. If the temperature exceeds 800 ° C, the phase transition of the particles may occur, resulting in cracks or deformation of the pore structure.

In one embodiment, the pyrolysis and sintering may be performed in a box sintered furnace or a tubular furnace as non-limiting examples.

During the carbonization of the first organic polymer by pyrolysis, if a small amount of oxygen is also introduced into the sintering furnace, oxidation may occur and a non-uniform carbon layer may be formed with defects on the surface of the separator. In one embodiment, the sintering furnace may be constructed to block external oxygen inflow while continuously flowing ultrahigh purity He (99.9999%). During the pyrolysis process, He is supplied as a carrier gas at a flow rate of about 250 cc / min, and pyrolysis process can be performed after sufficiently flowing He. Also, in order to prevent the temperature gradient due to heat loss from occurring due to the characteristics of the sintering furnace (tube-type furnace), both ends of the separation membrane sample can be fixed with a ceramic refractory.

According to the present invention, a composite hollow fiber membrane in which a carbon molecular sieve is formed on a high-strength inorganic hollow fiber support can form bundles to provide a separation membrane module (FIG. 1, right side view). Thus, the separation membrane module can be used to separate a mixture of olefins of the same carbon number with paraffins (e.g. propylene / propane), nitrogen and hydrogen, nitrogen and propylene.

Also, the separation membrane module according to the present invention can be applied to a system such as a liquid energy carrier, production of chemical substances, oxygen generation, low emission of carbon dioxide, hydrogen-related technology, and carbon compound capture.

The asymmetric or composite membrane type CMS separation membrane according to the present invention is easier to manufacture than other inorganic membranes, has excellent productivity, and is excellent in production efficiency. In addition, the hollow-fiber type separator provides a high packing density, and when manufactured in the form of a composite membrane, it is easy to make a face-to-face through modularization.

The composite hollow fiber membrane according to the present invention exhibits excellent heat resistance, durability, chemical resistance, and mechanical strength, and has excellent permeability and selectivity, and has a composite membrane form of a porous support having a high strength and a carbon powder layer serving as a thin and dense active layer . In addition, the composite hollow fiber membrane of the present invention can separate very small molecules having similar sizes at a very high efficiency.

FIG. 1 is a schematic view of a CMS hollow fiber membrane manufactured according to one embodiment of the present invention and a membrane module having hollow fiber membranes.
Figure 2 shows the results of coating with (a) and (d) pure sol coating, (b) and (e) 2: And a water-coated gamma-alumina intermediate layer.
3 shows the gas permeability and selectivity of the? -Alumina hollow fiber membrane prepared using pure sol according to Production Example 2.
FIG. 4 is a SEM image showing a γ-alumina coating layer prepared by optimizing the ramping rate and immersion time from pure sol according to Production Example 2.
5 shows SEM images of the surface and cross-section of the CMS hollow fiber membrane produced according to Example 1. Fig.
6 shows average transmittance (a), mean pore size distribution (c), average transmittance (c), and average pore size distribution of the C-HF hollow fiber membrane prepared in Example 1.
7 shows the permeation performance (measured at 2 bar) of the CMS hollow fiber membrane prepared according to Example 1. FIG.
8 is a SEM image of a cross-section of the CMS hollow fiber membrane produced according to Example 2. Fig.

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, the following examples are intended to illustrate the present invention, but the scope of the present invention is not limited thereto.

Manufacturing example  1:? -Alumina support

A high strength α - alumina hollow support having an outer diameter of 2 - 3 mm was prepared by extrusion - phase transfer method.

The α-alumina powder having a particle size of 300~400 nm was mixed with the polysulfone polymer and formed into a hollow fiber by extrusion method and sintered at 1450 ° C. to obtain a porous α-alumina support. Commercialization Hyflux InoCep ^® α-alumina hollow fiber membrane has an outer diameter of 4 mm or more, while the prepared α-alumina support is 4 mm or less, which is a hollow fiber membrane having a smaller outer diameter. The average pore size of the prepared α-alumina support was 80 to 100 nm.

The single gas permeability and selectivity of N ₂ and SF ₆ for the pressure of the α-alumina support were measured. At 2 bar, the permeability of N ₂ and SF ₆ were 50,000 ~ 65,000 GPU and 35,000 ~ 45,000 GPU, respectively, and showed a selectivity of 1.25 ~ 1.35. It can be seen that there is a convective flow, that is, a large pore, which is lower than the Knudsen flow (N2 / SF6 = 2.3). Therefore, when the polymer coating is carried out without the γ-alumina intermediate layer, the polymer solution permeates into the large pores of the α-alumina support, making it difficult to form a uniform polymer thin film layer.

Manufacturing example  2: sol- Come to law  Formation of γ-alumina intermediate layer

In order to reduce the large pores of the a-alumina support, the sol-gel method, in which the nanoparticles are uniform in size and well dispersed, is introduced.

Water-based sol was prepared by dispersing aluminum tri-sec-butoxide (ATB) as a precursor in water and hydrolyzing and condensing it. The α-alumina support was then dip-coated on a Water-based sol and fired at 600 ° C.

Fig. 2 is a SEM image of gamma-alumina surface coated with boehmite sol (high concentration as-made sol) synthesized in pure state and sol mixed with water. 2 (a) and 2 (d) show γ-alumina coated with pure sol and cross-sectional images having a thickness of 3 μm and uniform coating. The results are fairly compact and homogeneous compared to the γ-alumina layer made using the γ-alumina nanoparticle dispersion solution. As the nano-sized γ-alumina particles are uniformly dispersed in the sol, it is considered that the coating is thin and uniform.

2 (b), (e), (c), and (f) show gamma-alumina surface and cross-sectional images of sol and water mixed at 2: 1 and 3: It can be seen that the coated γ-alumina thicknesses are 2 μm and 1 μm, respectively, and a very thin layer is formed compared to γ-alumina obtained by pure sol. However, as the thickness of γ-alumina became thinner, the coating layer became uneven and the defects increased noticeably.

3 shows the N ₂ and SF ₆ gas permeabilities of the alumina hollow fiber membrane coated with? -Alumina on the? -Alumina support of Production Example 1. FIG.

it can be confirmed that the hollow fiber membrane still has a high permeability even after γ-alumina coating. Therefore, the permeability of the CMS membrane is not lowered due to the introduction of the γ-alumina intermediate layer.

Figure 4 shows a gamma-alumina coating layer made by optimizing ramping rate and immersion time from pure sol. The immersion time was set to 1 ~ 2 s, and a thin layer of 1 ㎛ thick was formed by keeping the pulling up rate slower by 1 mm / s after immersion. It was confirmed that a thick layer was formed when the lifting speed after immersion was fast, and that a thin layer of γ-alumina intermediate layer was formed as the lifting speed was slower.

Example  1: Manufacture of CMS composite hollow fiber membrane

In order to maintain the constant temperature and humidity, the CMS composite hollow fiber membrane was prepared in a constant temperature and humidity chamber and was operated at an ambient temperature of 24 ° C and a humidity of 40% or less.

A water-based alumina sol synthesized from aluminum tri-sec-butoxide (ATB) was dispersed in water and hydrolyzed and condensed. The coating time was 2 sec and the ramping rate was 30 The γ-alumina intermediate layer was prepared by dip coating the α-alumina hollow support prepared in Preparation Example 1 under the condition of mm / s. The coated alumina support was sintered at 650 캜 (ramping rate: 1 캜 / min).

Next, a support in which the above-prepared γ-alumina intermediate layer was formed was immersed for 60 seconds in a polymer solution prepared by dissolving 3 g of polyimide (Matrimid 5218) in 97 ml of solvent NMP, dried at room temperature for 12 hours or more, Lt; / RTI > for 2 h.

Subsequently, oxygen was continuously flowed in a tubular furnace while ultrapure He (99.9999%) was continuously flowed. The pyrolysis process was performed for 1 h at a heating rate of 1 ° C / min, and CMS A composite hollow fiber membrane was prepared.

The surface and cross section of the prepared CMS composite hollow fiber membrane were photographed with a scanning electron microscope (manufacturer: JEOL, model name: JSM-6360) and are shown in FIG. The surface of the CMS composite hollow fiber membrane was very flat and a 1 ~ 2 ㎛ carbon layer was formed from the cross section.

The average pore size of the γ-alumina intermediate layer and the CMS composite hollow fiber membrane was measured using a nano permporometer (NPP), which is shown in FIG.

The permeability of the γ-alumina intermediate layer was higher than that of the CMS composite hollow fiber membrane due to its large pore size, and pore size was mostly present between 1 and 15 nm. On the contrary, the permeability of the CMS composite hollow fiber membranes decreased significantly during pore size measurement and the pore size distribution was between 0.25 and 4.75 nm. Particularly, since there is a high pore distribution at 1 nm or less and large pores are distributed in the range of 2 to 4 nm, it is believed that the separation occurs at a pore size of 1 nm or less, It is expected to happen.

Modules and permeators were fabricated to measure the permeation performance of CMS composite hollow fiber membranes. In order to analyze the permeation behavior with temperature, measurements were made in the oven, and a heating line was connected before and after the module. For the single gas, 99.99% propylene and propane gas were used and the permeability was measured using a bubble flow meter. In the case of mixed gas, the mixing ratio of gas was controlled by using MFC for each single gas for measuring the permeability according to the mixed gas ratio. The pressure was controlled by a cross flow method using a back pressure regulator (BPR) on the retentate of the module. The permeability and selectivity of the gas from the permeate were calculated using a bubble flow meter and GC. The CMS composite hollow fiber membrane of Example 1 retained high permeability and selectivity in the mixed gas permeation experiment.

The permeation performance of the CMS composite hollow fiber membrane of Example 1 was measured and shown in FIG. At 2 bar, the hydrogen permeability was significantly high (270 ~ 380 GPU) and the propylene permeability was 35 ~ 41 GPU.

Table 1 below shows the selectivities for hydrogen / nitrogen and propane / propylene. The propane / propylene selectivity at 2 bar was significantly higher than the conventional carbon film performance (C ₃ H ₆ permeability: 20-35 GPPU, C3H6 / C3H8 selectivity: 11-25) Show that propane and propylene having similar molecular sizes can be separated to a high level as a result of molecular sieve separation observed in < RTI ID = 0.0 >< / RTI > It was confirmed that the permeation rate was improved because of the similar size of molecular sieve by micropores existing in the CMS composite hollow fiber membranes, and the porosity was increased by the pores existing in the size of several nanometers. In addition, the permeability was further improved by the thin separation layer, which is an advantage of the hollow fiber membrane.

Pressure (bar) H ₂ / N ₂ C ₃ H ₆ / C ₃ H ₈ 2 bar 29.30 39.04

Example  2: Preparation of CMS composite hollow fiber membrane

Except that a carbon layer was formed by using a 4 to 6 wt% polymer solution in which polyimide (Matrimid 5218) was dissolved in THF having high volatility and easy to coat instead of solvent NMP, through the same procedure as in Example 1 CMS composite hollow fiber membrane. At this time, the drying time could be reduced to less than 1 h at room temperature after polymer coating.

The cross section of the CMS composite hollow fiber membrane was photographed with a scanning electron microscope (JEOL, model: JSM-6360) and is shown in FIG. On the γ-alumina layer of about 1 μm, a CMS layer having a thickness of 3 to 4 μm can be identified. Compared with CMS membranes prepared using NMP, it appears to be thicker. This is because the polymer solution prepared by using NMP as a solvent takes a long time to evaporate the solvent after coating and the polymer solution flows down by gravity to form a thin and uneven layer. On the other hand, when THF is used as a solvent, evaporation of the solvent occurs rapidly, and the coating layer is formed uniformly and thickly.

Also, the propylene / propane permeation performance was measured at 2 bar using the CMS composite hollow fiber membrane prepared in Example 2, and the results are shown in Table 2 below. Initial propylene single gas permeability was 25 GPU, which was lower than before. This result shows that the carbon layer thickness is thicker than the CMS hollow fiber membrane using NMP as a solvent. The permeability of pure propylene decreased to 15.76 GPU after more than 60 h of CMS composite hollow fiber membrane, which is considered to be oxidation and moisture adsorption phenomenon of CMS hollow fiber membrane. The measured propylene / propane (38/62) mixed gas permeation result shows that the propylene permeability is 15.13 GPU, which is slightly lower than that of the single gas. However, the selectivity was 33.15, which was still higher than that of the polymer membrane (M. Das, W.J. Koros, Performance of 6FDA-6FpDA polyimide for propylene / propane separations, J. Membr. Sci. The decrease in permeability appears to be due to the competitive permeation of propylene and propane.

Claims (12)

A hollow fiber composite membrane having an outer diameter of 0.1 mm to 4 mm, an inner diameter of 0.05 mm to 3 mm, and a thickness of 0.01 mm to 2 mm,
An inorganic hollow support having an outer diameter of 4 mm or less and having a first pore size, prepared using a first inorganic particle having a first particle size;
A sol containing a second inorganic particle or a precursor thereof is filled in the pores on the surface of the inorganic hollow fiber support to form a second inorganic particle having a second particle size smaller than the first particle size on the inorganic hollow fiber support surface A first layer filling the pores of the first layer; And
And a second layer containing a carbon molecular sieve formed by coating a solution containing the first organic polymer on the first layer and then pyrolysis.
The composite hollow fiber membrane according to claim 1, wherein the thickness of the second layer containing carbon molecular sieve is 0.1 占 퐉 to 10 占 퐉.
The method of claim 1, wherein the first layer is formed by filling a pores of a surface of the inorganic hollow fiber support with a sol containing a second inorganic particle or a precursor thereof and forming a second inorganic particle to reduce porosity Wherein the second inorganic particles fill the pores of the surface of the inorganic hollow fiber support by gelling with a gel of the formed tissue.
The composite hollow fiber membrane according to claim 1, which has a pore structure capable of separating olefins having the same carbon number from paraffin.
The composite hollow fiber membrane according to claim 1, characterized by having a pore structure capable of separating nitrogen and hydrogen.
A method for producing the composite hollow fiber membrane according to any one of claims 1 to 5,
A first step of coating an inorganic hollow support having an outer diameter of 4 mm or less and having a first pore size using a first inorganic particle with a sol containing a second inorganic particle or a precursor thereof;
A second step of gelling a sol filled in the pores of the surface of the inorganic hollow fiber support with a gel of a tissue formed by connecting the second inorganic particles;
A third step in which a second inorganic particle having a second particle size smaller than the first particle size is formed by drying or heat treatment to form a first layer filled with pores on the surface of the inorganic hollow fiber support;
A fourth step of coating the first organic polymer-containing solution on the first layer; And
And a fifth step of pyrolysis of the coated first organic polymer to form a second layer containing carbon molecular sieve.
7. The method of claim 6, wherein the ramping rate of the dip coating in the first step is 0.1 to 30 mm / s.
7. The method for producing a composite hollow fiber membrane according to claim 6, wherein the pyrolysis is carried out at 500 to 800 DEG C for 1 minute to 10 hours in the fifth step.
A separation membrane module having the composite hollow fiber membranes according to any one of claims 1 to 5.
A method for separating olefins and paraffins having the same carbon number using the separation membrane module according to claim 9.
A process for producing a separated olefin or separated paraffin comprising separating an olefin and a paraffin-containing gas using the separation membrane module according to claim 9.
A method for separating nitrogen and hydrogen using the separation membrane module according to claim 9.

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