CHA-DDR series zeolite separation membrane and its manufacturing method

Abstract

The present invention can provide a CHA-DDR series zeolite separation membrane comprising: a first layer comprising a CHA structure and a DDR structure; and a second layer comprising a DDR structure provided on the first layer; the CHA-DDR series zeolite separation membrane is in the form of a film having a thickness of 100 nm to 5 μm and comprises a CHA structure and a DDR structure.

Description

[Technical field]

[0001] The present invention relates to a CHA-DDR series zeolite separation membrane and a manufacturing method thereof, and more particularly to a thin CHA-DDR series zeolite separation membrane with high permeability, which is produced by using a novel manufacturing method, and a manufacturing method thereof. [Background technology]

[0002] Zeolite is a catalyst for converting methanol into gasoline and denitrifying soot. It is made of SiO4 and AlO4 - Zeolite is an alumina-silica crystalline molecular sieve with a regular three-dimensional framework structure in which tetrahedra are connected in a geometrical shape, and the tetrahedra are connected to each other by sharing oxygen, and the framework has channels and cavities that are connected to each other. Due to these characteristics, zeolites have excellent ion exchange properties and are used in a variety of applications such as catalysts, adsorbents, molecular sieves, ion exchangers, and separation membranes.

[0003] Meanwhile, in the case of zeolite separation membranes for separating mixed gases, despite their high potential for capturing carbon dioxide, they are difficult to use in actual industries and processes because conventional manufacturing methods cannot reproducibly produce zeolite separation membranes with high performance.

[0004] Therefore, various researches have been conducted on a method for reproducibly manufacturing a large-area zeolite separation membrane having high gas permeability and high gas separation performance. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Republic of Korea Registered Patent 10-0861012 Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to provide a CHA-DDR series zeolite separation membrane capable of effectively separating carbon dioxide, and a method for producing the same.

[0007] Another object of the present invention is to provide a CHA-DDR series zeolite separation membrane which has high reproducibility, can be easily produced in a large area, and has improved industrial applicability, and a method for producing the same. [Means for solving the problem]

[0008] According to one aspect of the present invention, an embodiment of the present invention includes a CHA-DDR series zeolite separation membrane including a first layer including a CHA structure and a DDR structure; and a second layer including a DDR structure provided on the first layer; the CHA-DDR series zeolite separation membrane is in the form of a film having a thickness of 100 nm to 5 um and includes a CHA structure and a DDR structure.

[0009] In one embodiment, the second layer includes a pyramidal surface portion, and a (101) peak may appear when measured by XRD using CuKα radiation.

[0010] In one embodiment, the first layer may have an average thickness of 50 nm to 2 um, and the second layer may have an average thickness of 10 nm to 2 um.

[0011] In one embodiment, the CHA structure of the first layer is manufactured from a CHA precursor solution, and the CHA precursor solution includes a first organic structure derivative, SiO2, H2O, a sodium compound, and an aluminum compound, and the first organic structure derivative, SiO2, H2O, sodium compound, and aluminum compound may be in a molar ratio of 0.1-1000:100:100-50000:0-500:0-100.

[0012] In one embodiment, the first organic structure derivative may be any one or more of TMAdaOH (N,N,N-trimethyl adamantylammonium hydroxide), TMAdaBr (N,N,N-trimethyl adamantylammonium bromide), TMAdaF (N,N,N-trimethyl adamantylammonium fluoride), TMAdaCl (N,N,N-trimethyl adamantylammonium chloride), TMAdaI (N,N,N-trimethyl adamantylammonium iodide), TEAOH (tetraethylammonium hydroxide), TEABr (tetraethylammonium bromide), TEAF (tetraethylammonium fluoride), TEACl (tetraethylammonium chloride), TEAI (tetraethylammonium iodide), dipropylamine, and cyclohexylamine.

[0013] In one embodiment, the DDR structure of the first or second layer is manufactured from a DDR precursor solution, the DDR precursor solution including SiO2, a second organic structure derivative, H2O, a sodium compound, and an aluminum compound, and the SiO2, the second organic structure derivative, H2O, the sodium compound, and the aluminum compound may each have a molar ratio of 100:1 to 1000:10 to 100000:0 to 500:0 to 100.

[0014] In one embodiment, the second organic structure derivative may be any one or more of methyltropinium iodide, methyltropinium bromide, methyltropinium fluoride, methyltropinium chloride, methyltropinium hydroxide, quinuclidinium, TEAOH (tetraethylammonium hydroxide), TEABr (tetraethylammonium bromide), TEAF (tetraethylammonium fluoride), TEACl (tetraethylammonium chloride), TEAI (tetraethylammonium iodide), ethylenediamine, and adamantylamine.

[0015] In one embodiment, the carbon dioxide permeability is 1×10 -9 mol m -2 ·s -1 ·Pa -1 ~1×10 -5 mol m -2 ·s -1 ·Pa -1 may be also possible.

[0016] In one embodiment, the CHA structure may be included in an amount of 25 parts by weight to 95 parts by weight per 100 parts by weight of the entire crystal structure of the CHA structure and DDR structure of the first layer and the second layer.

[0017] In one embodiment, when carbon dioxide and methane are mixed gases in a molar ratio of 50:50, the recovery rate of the carbon dioxide may be 10% to 100%, and the purity may be 50% to 100%, and the recovery rate of the methane may be 50% to 100%, and the purity may be 30% to 100%.

[0018] In one embodiment, when carbon dioxide and nitrogen are in a mixed gas with a molar ratio of 15:85, the recovery rate of the carbon dioxide may be 10% to 100%, and the purity may be 20% to 100%, and the recovery rate of the nitrogen may be 30% to 100%, and the purity may be 30% to 100%.

[0019] In one embodiment, the CHA-DDR series zeolite separation membrane can separate gas and gas mixtures, gas and liquid mixtures, and liquid and liquid mixtures.

[0020] In one embodiment, the method may include a primary growth step of forming seed particles including a CHA structure by a hydrothermal synthesis method using a CHA precursor solution including a first organic structure derivative; and a secondary growth step of forming a layered structure including a DDR structure so as to cover the seed particles by a hydrothermal synthesis method using a DDR precursor solution including a second organic structure derivative; and a method for producing a CHA-DDR series zeolite separation membrane including a CHA structure and a DDR structure in the form of a film having a thickness of 100 nm to 5 um.

[0021] In one embodiment, the primary growth step may include synthesizing seed particles having a CHA structure by a hydrothermal synthesis method using the CHA precursor solution, dispersing the seed particles in a solvent to prepare a suspension, immersing a support in the suspension to coat the seed particles on a surface of the support, drying the support coated with the seed particles, and after the drying is completed, heat treating the support coated with the seed particles at 300°C to 550°C for 1 hour to 24 hours.

[0022] In one embodiment, the secondary growth step may include adding a DDR precursor solution to the support on which the seed particles are coated, and carrying out hydrothermal synthesis.

[0023] In one embodiment, in the primary growth step, the seed particles are provided in the form of a plurality of particles on a support, and the support may include any one or more of α-alumina, γ-alumina, polypropylene, polyethylene, polytetrafluoroethylene, polysulfone, polyimide, silica, glass, mullite, zirconia, titania, yttria, ceria, vanadia, silicon, stainless steel, carbon, calcium oxide, and phosphorus oxide.

[0024] In one embodiment, the support has a permeability of 1×10 -6 mol m -2 ·s -1 ·Pa -1 ~1×10 -4 mol m -2 ·s -1 ·Pa -1 The tubular material may be provided with a high permeability of 100 nm to 100 nm.

[0025] In one embodiment, the seed particles may be formed in a plurality of pieces, and the average length of the seed particles may be 10 nm to 1 μm.

[0026] In one embodiment, in the primary growth step, the hydrothermal synthesis may be carried out for 6 hours to 400 hours and at a temperature range of 100°C to 250°C.

[0027] In one embodiment, in the secondary growth step, the hydrothermal synthesis may be carried out for 6 hours to 400 hours and at a temperature of 100°C to 250°C.

[0028] In one embodiment, the CHA precursor solution and the DDR precursor solution each contain Si and Al, and the CHA structure may have a Si:Al molar ratio reference value of 100:0-10, and the DDR structure may have a Si:Al molar ratio reference value of 100:0-10.

[0029] In one embodiment, the method further includes a heat treatment step after the secondary growth step, and the heat treatment step may be performed in an ozone atmosphere at a temperature range of 100° C. to 300° C.

[0030] In one embodiment, the CHA-DDR series zeolite separation membrane may contain 1 wt % or less of adamantylamine inside the pores. Effect of the Invention

[0031] According to the present invention as described above, it is possible to provide a CHA-DDR series zeolite separation membrane having excellent carbon dioxide separation performance and capable of separating carbon dioxide at high purity, and a method for producing the same.

[0032] In addition, the present invention provides a CHA-DDR series zeolite separation membrane and a manufacturing method thereof that can be manufactured in a large area with high reproducibility by applying a novel method and can be easily applied industrially. [Brief description of the drawings]

[0033] [Figure 1] FIG. 2 is a schematic diagram illustrating a method for producing a CHA-DDR series zeolite separation membrane according to an embodiment of the present invention. [Diagram 2] The schematic configuration of the cell and module for evaluating the separation performance is shown. [Diagram 3] The SEM image, XRD pattern, STEM image, and electron diffraction pattern of the CD separator according to the present embodiment are shown. [Figure 4] The STEM image and the electron diffraction pattern of the CD separator according to the present embodiment are shown. [Diagram 5] Electron diffraction patterns are shown for the indicated portions of the STEM images in FIG. [Figure 6] 1 shows SEM images and XRD patterns of CD-P particles according to an embodiment of the present invention depending on heat treatment conditions. [Figure 7]SEM and FCOM images of the CD separation membranes after air and ozone heat treatments. [Figure 8] SEM images of the CD separation membrane under different heat treatment conditions. [Figure 9] These are the results of confirming the CO2 / CH4 separation performance of CD separation membranes produced by air heat treatment and ozone heat treatment, respectively. [Figure 10] These are the results of evaluating the CO2 / CH4 separation performance of the CD-1-Cell and CD-4-Module. [Figure 11] This is the result of confirming the long-term stability of CD-1-Cell. [Figure 12] The results show the permeability and SF of a CO2 / CH4 equimolar gas mixture through multiple CD separation membranes. [Figure 13] The results show the separation performance of the CD-1-Cell for a CO2 / N2 mixture. [Figure 14] The results show the separation performance of CD-1-Cell for CO2 / N2 mixtures under dry and wet conditions. [Figure 15] This shows the separation performance of CD-1-Cell for CO2 / N2 mixtures under different temperature conditions. [Figure 16] These are the results of evaluating the CO2 / CH4 separation performance for the CD-1-Cell and CD-4-Module. [Figure 17] FIG. 17 is a graph showing recovery and purity under the dry and wet conditions of FIG. 16. [Figure 18] This shows the results of comparing the performance of CD-1-Cell, CD-4-Module and other separation membranes. [Figure 19] FIG. 18 shows schematic features of other separation membranes. [Figure 20] This shows the results of evaluating the liquid separation performance using ozone heat-treated CD separation membranes. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0034] Other specific details of the embodiments are included in the detailed description and drawings.

[0035] The advantages and features of the present invention, and the methods for achieving them, will become clear with reference to the embodiments described below in detail with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be embodied in various different forms, and unless otherwise specified in the following description, all numbers, values ​​and / or expressions expressing components, reaction conditions, and contents of components in the present invention are approximate values ​​reflecting various uncertainties of measurement that occur in obtaining such values ​​while such numbers are inherently different, and therefore should be understood to be modified in all cases by the term "about". Furthermore, when a numerical range is disclosed in this description, such range is continuous and includes all values ​​from the minimum value to the maximum value, inclusive, unless otherwise specified. Furthermore, when such a range refers to a constant, it includes all constants from the minimum value to the maximum value, inclusive, unless otherwise specified. Also, when a range is described for a variable in the present invention, it should be understood that the variable includes all values ​​within the described range, including the described endpoints of the range. For example, the range "5-10" should be understood to include not only the values ​​5, 6, 7, 8, 9, and 10, but also any subranges such as 6-10, 7-10, 6-9, 7-9, etc., and any values ​​between the constants that are valid within the described range, such as 5.5, 6.5, 7.5, 5.5-8.5, and 6.5-9. For example, the range "10%-30%" should be understood to include not only values ​​such as 10%, 11%, 12%, 13%, and all constants up to and including 30%, but also any subranges such as 10%-15%, 12%-18%, 20%-30%, etc., and any values ​​between the constants that are valid within the described range, such as 10.5%, 15.5%, 25.5%, etc.

[0036] FIG. 1 is a schematic diagram illustrating a method for preparing a CHA-DDR series zeolite separation membrane according to one embodiment of the present invention.

[0037] 1, a CHA-DDR series zeolite separation membrane 100 including a CHA (chabazite) structure and a DDR (deca-dodecasil 3 rhombohedral) structure according to an embodiment of the present invention may include a first layer 110 including a CHA structure c and a DDR structure d, and a second layer 120 including the DDR structure d provided on the first layer 110, and may be in the form of a film having a thickness of 100 nm to 5 um. The second layer 120 includes a pyramidal surface portion, and a (101) plane peak may appear when measured by XRD using CuKα radiation.

[0038] Generally, biogas is an environmentally friendly and sustainable energy resource that can replace or supplement conventional fossil fuels. Meanwhile, in order to use biogas, it is necessary to effectively separate CO2 (0.33 nm) and CH4 (0.38 nm) to upgrade the biogas. In this way, a DDR zeolite separation membrane can be used to upgrade biogas, but the DDR zeolite separation membrane has a problem in that the manufacturing method is difficult. Specifically, in order to manufacture the DDR zeolite separation membrane, the particle size of the seed particles is large, the synthesis time is long, and it is difficult to ensure the reproducibility of the synthesis, so that commercial application has been limited. That is, although the conventional DDR zeolite separation membrane can effectively separate gases such as CO2 and CH4 contained in biogas, it is difficult to manufacture a separation membrane having a thin thickness.

[0039] Meanwhile, the CHA-DDR series zeolite separation membrane 100 according to the present embodiment has improved separation ability, high reproducibility in the manufacturing method, and can be manufactured to a thinner thickness than the conventional DDR zeolite separation membrane, and is easily commercialized.

[0040] The CHA-DDR series zeolite separation membrane 100 according to the present embodiment may include a first layer 110 including a CHA structure c and a DDR structure d, and a second layer 120 including the DDR structure d and provided on the first layer 110. For example, the first layer 110 and the second layer 120 may be included, and the thickness of the first layer 110 and the second layer 120 may be controlled, and the entire CHA-DDR series zeolite separation membrane 100 including the first layer 110 and the second layer 120 may be provided in the form of a film having a thickness of 100 nm to 5 um.

[0041] In addition, the CHA-DDR series zeolite separation membrane 100 may be provided in a tubular or tube-like shape, and a plurality of tubular separation membranes may be connected to each other to be used for upgrading biogas or separating mixed gases. By providing the CHA-DDR series zeolite separation membrane 100 in a tubular or tube-like shape, the CHA-DDR series zeolite separation membrane 100 may be designed in the form of a single cell or may be manufactured in the form of a module consisting of a plurality of cells, which may be more efficient when applied to an actual process. By separating mixed gases through the internal cavities of the separation membrane formed in a tubular shape, the gas separation efficiency may be further improved.

[0042] Specifically, the CHA-DDR series zeolite separation membrane 100 may be prepared by forming seed particles including a CHA structure c on a support s. The seed particles may be used to secondarily grow zeolite including a DDR structure d, thereby forming the CHA-DDR series zeolite separation membrane 100 including the first layer 110 and the second layer 120.

[0043] If the thickness of the CHA-DDR series zeolite separation membrane 100 is less than 100 nm, it is difficult to obtain high-purity CO2, and separation is particularly difficult in the case of a mixed gas containing water vapor, which is problematic. If the thickness exceeds 5 um, the size and processing cost of the device using the CHA-DDR series zeolite separation membrane 100 increases, and the amount of mixed gas that can be processed at one time decreases. In addition, in the case of conventional DDR zeolite separation membranes, it was difficult to manufacture a separation membrane with a thickness of 7 um or less due to limitations in the method of synthesizing DDR zeolite, but the CHA-DDR series zeolite separation membrane 100 according to the present embodiment can be manufactured with a thickness of 5 um or less, thereby further improving the separation ability and separation efficiency of mixed gas.

[0044] The first layer 110 may have an average thickness of 50 nm to 2 um, and the second layer 120 may have an average thickness of 10 nm to 2 um. If the average thickness of the first layer 110 is less than 50 nm, it is difficult to form a stable CHA seed structure and to grow the second layer 120 having a DDR structure d on the first layer 110, and if it exceeds 2 um, the overall thickness of the CHA-DDR series zeolite separation membrane 100 is unnecessarily increased. In addition, the second layer 120 is provided with the above thickness, so that biogas can be effectively upgraded and high-purity CO2 can be separated.

[0045] The first layer 110 is a layer in which CHA structure c and DDR structure d are mixed, and the contents of CHA structure c and DDR structure d having different pore sizes and properties can be controlled. The second layer 120 may be composed of only DDR structure d, and the outermost surface of the second layer 120 may include a pyramidal surface portion. The CHA-DDR series zeolite separation membrane 100 may show a (101) plane peak when measured by XRD using CuKα radiation.

[0046] For example, the CHA-DDR series zeolite separation membrane 100 according to the present embodiment can have a pyramidal surface portion, which is a characteristic of only the DDR structure d, and can simultaneously have an XRD peak of the (101) plane, which is a characteristic of only the CHA structure c, by being manufactured by a novel method. In addition, the CHA-DDR series zeolite separation membrane 100 according to the present embodiment can be manufactured with a thinner thickness than the conventional DDR zeolite separation membrane with good reproducibility, and can have improved biogas upgrading performance and mixed gas separation ability.

[0047] The CHA structure may be included in an amount of 25 to 95 parts by weight per 100 parts by weight of the entire crystal structure of the CHA structure and the DDR structure of the first layer 110 and the second layer. In general, zeolite can be manufactured in the form of a film consisting of only the same crystal structure through secondary growth using seed particles having the same crystal structure. Meanwhile, in the present embodiment, the seed particles including the CHA structure are controlled within the above range, so that the DDR structure can be manufactured in the form of a thin film through secondary growth.

[0048] The CHA structure of the first layer 110 may be manufactured from a CHA precursor solution. The CHA precursor solution may include a first organic structure derivative, SiO2, H2O, a sodium compound, and an aluminum compound. For example, the sodium compound may include sodium oxide or sodium hydroxide, specifically Na2O3, NaOH. Also, the aluminum compound may include aluminum oxide or aluminum hydroxide, specifically Al2O3, Al(OH)3.

[0049] The first organic structure derivative, SiO2, H2O, sodium compound, and aluminum compound may each have a molar ratio of 0.1 to 1000:100:100 to 50000:0 to 500:0 to 100. Specifically, the first organic structure derivative, SiO2, H2O, sodium compound, and aluminum compound may each have a molar ratio of 1 to 100:100:500 to 30000:5 to 50:0.5 to 20, and more specifically, may be 20:100:1600:20:5.

[0050] The first organic structure derivative may be any one or more of TMAdaOH (N,N,N-trimethyl adamantylammonium hydroxide), TMAdaBr (N,N,N-trimethyl adamantylammonium bromide), TMAdaF (N,N,N-trimethyl adamantylammonium fluoride), TMAdaCl (N,N,N-trimethyl adamantylammonium chloride), TMAdaI (N,N,N-trimethyl adamantylammonium iodide), TEAOH (tetraethylammonium hydroxide), TEABr (tetraethylammonium bromide), TEAF (tetraethylammonium fluoride), TEACl (tetraethylammonium chloride), TEAI (tetraethylammonium iodide), dipropylamine, and cyclohexylamine.

[0051] The DDR structure d of the first layer 110 or the second layer 120 may be manufactured with a DDR precursor solution. The DDR precursor solution may include SiO2, a second organic structure derivative, H2O, a sodium compound, and an aluminum compound. For example, the sodium compound may include sodium oxide or sodium hydroxide, specifically Na2O3, NaOH. Also, the aluminum compound may include aluminum oxide or aluminum hydroxide, specifically Al2O3, Al(OH)3.

[0052] The molar ratio of each of the SiO2, second organic structure derivative, H2O, sodium compound, and aluminum compound may be 100:1 to 1000:10 to 100000:0 to 500:0 to 100. Specifically, the molar ratio of each of the SiO2, second organic structure derivative, H2O, sodium compound, and aluminum compound may be 100:10 to 800:500 to 30000:0 to 50:0 to 20, and more specifically, may be 100:450:11240:0:0.

[0053] The second organic structure derivative may be one or more of methyltropinium iodide, methyltropinium bromide, methyltropinium fluoride, methyltropinium chloride, methyltropinium hydroxide, quinuclidinium, TEAOH (tetraethylammonium hydroxide), TEABr (tetraethylammonium bromide), TEAF (tetraethylammonium fluoride), TEACl (tetraethylammonium chloride), TEAI (tetraethylammonium iodide), ethylenediamine, and adamantylamine.

[0054] Specifically, the second organic structure derivative may be a combination of two or more substances, more specifically, a combination of one or more substances different from adamantylamine. For example, the second organic structure derivative may contain adamantylamine and ethylenediamine, and when the adamantylamine and ethylenediamine are used in combination, the ethylenediamine may be used in a molar ratio of 5 to 20 times the adamantylamine. In addition, the adamantylamine and ethylenediamine may be used in a molar ratio of 10 to 100:50 to 1000.

[0055] The CHA-DDR series zeolite separation membrane 100 can be manufactured by forming seed particles in the CHA precursor solution and then secondary growing them in the DDR precursor solution. The CHA precursor solution and the DDR precursor solution can be used within the above ranges to form a structurally stable zeolite.

[0056] In general, zeolite separation membranes are usually manufactured using a secondary growth method, and in this case, the crystal structure of the zeolite that constitutes the seed particles and the zeolite that constitutes the entire separation membrane must be the same. In the commonly used method of synthesizing ZSM-58 zeolite with a DDR structure using methyltropinium iodide as an organic structure-directing agent (OSDA), the seed particles are formed very large, and when they are manufactured into a film shape by secondary growth, the thickness of the film manufactured is too thick, which reduces the permeability, which is a problem.

[0057] Meanwhile, in the present embodiment, the CHA precursor solution and the DDR precursor solution are used to control the particle size of the seed particles to be small, and thus the seed particles can be manufactured in the form of a thin film, and at the same time, a CHA-DDR series zeolite separation membrane 100 including both the CHA structure and the DDR structure can be manufactured. Specifically, the first organic structure derivative may include methyltropinium iodide or 1-adamantylamine (ADA), and the second organic structure derivative may be 1-adamantylamine (ADA) or ethylenediamine.

[0058] The CHA-DDR series zeolite separation membrane 100 has a carbon dioxide permeability of 1×10 -9 mol m -2 ·s -1 ·Pa -1 ~1×10 -5 mol m -2 ·s -1 ·Pa -1 may be also possible.

[0059] In addition, the CHA-DDR series zeolite separation membrane 100 may separate carbon dioxide (CO2) gas from a gas mixture, and the inflow rate of the gas mixture may be 25 mL / min to 4000 mL / min.

[0060] When carbon dioxide and methane are mixed in a molar ratio of 50:50, the CHA-DDR series zeolite separation membrane 100 may have a carbon dioxide recovery rate of 10% to 100% and a purity of 50% to 100%, and a methane recovery rate of 50% to 100% and a purity of 30% to 100%.

[0061] In addition, when the CHA-DDR series zeolite separation membrane 100 is a mixed gas of carbon dioxide and nitrogen with a molar ratio of 15:85, the carbon dioxide recovery rate may be 10% to 100% and the purity may be 20% to 100%, and the nitrogen recovery rate may be 30% to 100% and the purity may be 30% to 100%.

[0062] The CHA-DDR series zeolite separation membrane 100 according to the present embodiment is manufactured to a thickness in the above range and includes a first layer 110 including the CHA structure c and the DDR structure d and a second layer 120 consisting only of the DDR structure d, thereby achieving a carbon dioxide permeability in the above range at the inflow velocity of the gas mixture.

[0063] The CHA-DDR series zeolite separation membrane can separate a gas-gas mixture, a gas-liquid mixture, and a liquid-liquid mixture. Specifically, it can separate substances that are difficult to separate from each other, such as mixtures of polar substances and mixtures of non-polar substances, or substances that have similar molecular sizes. In addition, the CHA-DDR series zeolite separation membrane can separate not only a mixture of gas and liquid having different phases, but also a mixture of gas and gas, and a mixture of liquid and liquid, with high separation performance. Specifically, in the mixture of liquid and liquid, the liquids may be made of either polar substances or non-polar substances.

[0064] For example, the gas and gas mixture, the gas and liquid mixture, and the liquid and liquid mixture may each be composed of two or more substances. For example, the gas and gas mixture may be a mixture of three or more gases, and one or two gases may be separated at the same time.

[0065] According to another aspect of the present invention, the present invention may include a method for producing a CHA-DDR series zeolite separation membrane, the method including: a first growth step of forming seed particles including a CHA structure produced by a hydrothermal synthesis method using a CHA precursor solution including a first organic structure derivative; and a second growth step of forming a layered structure including a DDR structure so as to cover the seed particles by a hydrothermal synthesis method using a DDR precursor solution including a second organic structure derivative. The CHA-DDR series zeolite separation membrane may include a CHA structure and a DDR structure, and may be provided in the form of a film having a thickness of 100 nm to 5 um.

[0066] The primary growth step may include synthesizing seed particles having a CHA structure by a hydrothermal synthesis method using the CHA precursor solution, dispersing the seed particles in a solvent to prepare a suspension, immersing a support in the suspension to coat the seed particles on a surface of the support, drying the support coated with the seed particles, and after the drying is completed, heat treating the support coated with the seed particles at 300°C to 550°C for 1 hour to 24 hours.

[0067] The support may include a pipe-shaped tubular support having an internal space, and the seed particles may be provided on the outer surface of the support by dip coating. For example, when the support is a tubular support having an internal space, one end and the other end can be covered before being immersed in the suspension, thereby preventing the seed particles from being coated on the inside of the tubular support.

[0068] The solvent may include at least one of ethanol, methanol, butanol, isopropanol, toluene, xylene, benzene, methylene chloride, chloroform, dioxane, tetrahydrofuran (THF), acetone, dimethylsulfoxide (DMSO), dimethylformamide (DMF), 1-methyl-2-pyrrolidone (NMP), and deionized water. Specifically, the solvent may be ethanol or deionized water.

[0069] The suspension may contain 0.001 to 0.5 parts by weight of seed particles based on 100 parts by weight of the suspension. If the amount of the seed particles is less than 0.001 parts by weight, the amount of the seed particles coated on the surface of the tubular support is too small, which may cause a problem during secondary growth, and if the amount of the seed particles is more than 0.5 parts by weight, the amount of the seed particles is not uniformly coated on the surface of the tubular support, which may cause a problem. Specifically, the amount of the seed particles may be 0.05 to 0.1 parts by weight.

[0070] Additionally, the suspension may be subjected to, for example, ultrasonic agitation prior to impregnating the tubular support, to provide a more uniform distribution of seed particles within the suspension.

[0071] The heat treatment may be performed at 300° C. to 550° C. for 1 hour to 24 hours. By performing the heat treatment within the above range, it is possible to remove a solvent that may be contained in the seed particles, and to allow the DDR precursor solution to be well impregnated into the surfaces of the seed particles in the secondary growth step.

[0072] The secondary growth step may include adding a DDR precursor solution and the tubular support coated with the seed particles, and performing hydrothermal synthesis. The DDR precursor solution may be provided in a film form consisting of only the DDR structure by hydrothermal synthesis to form a zeolite crystal structure including the DDR structure so as to surround the seed particles, and then by secondary growth.

[0073] In the method for producing a CHA-DDR series zeolite separation membrane according to the present embodiment, a CHA structure and a DDR structure, which are different crystal structures, may be formed by heteroepitaxial growth, and the membrane may be manufactured in the form of a film having the physical properties of a DDR structure as a whole while having a CHA structure therein.

[0074] In the primary growth step, the seed particles may be provided in the form of a plurality of particles on a support, which may include at least one of α-alumina, γ-alumina, polypropylene, polyethylene, polytetrafluoroethylene, polysulfone, polyimide, silica, glass, mullite, zirconia, titania, yttria, ceria, vanadia, silicon, stainless steel, carbon, calcium oxide, and phosphorus oxide.

[0075] The support is 1×10 -6 mol m -2 ·s -1 Pa-1~1×10 -4 mol m -2 ·s -1 ·Pa -1 The tubular material may be provided with a high permeability of 100 nm to 100 nm.

[0076] The seed particles may be formed in a plurality of pieces, and the average length of the seed particles may be 10 nm to 1 um. When the average length of the seed particles is less than 10 nm, the particle size of the seed particles is too small compared to the pores present on the surface of the support, causing a problem of the seed particles being inserted into the support, making it difficult to form the seed particles, and making it difficult to uniformly form the first layer. When the average length of the seed particles exceeds 1 um, the particle size of the seed particles is too large, causing problems such as adjacent seed particles overlapping each other, making it difficult to uniformly form the DDR structure. Specifically, the seed particles may be 100 nm to 1 um, or 200 nm to 1 um, or 200 nm to 700 nm, or 200 nm to 500 nm.

[0077] In the primary growth step, the CHA precursor solution may include a first organic structure derivative, SiO2, H2O, a sodium compound, and an aluminum compound. For example, the sodium compound may include sodium oxide or sodium hydroxide, specifically Na2O3, NaOH. Also, the aluminum compound may include aluminum oxide or aluminum hydroxide, specifically Al2O3, Al(OH)3.

[0078] The first organic structure derivative, SiO2, H2O, sodium compound, and aluminum compound may each have a molar ratio of 0.1 to 1000:100:100 to 50000:0 to 500:0 to 100. Specifically, the first organic structure derivative, SiO2, H2O, sodium compound, and aluminum compound may each have a molar ratio of 1 to 100:100:500 to 30000:5 to 50:0.5 to 20, and more specifically, may be 20:100:1600:20:5.

[0079] The first organic structure derivative may be any one or more of TMAdaOH (N,N,N-trimethyl adamantylammonium hydroxide), TMAdaBr (N,N,N-trimethyl adamantylammonium bromide), TMAdaF (N,N,N-trimethyl adamantylammonium fluoride), TMAdaCl (N,N,N-trimethyl adamantylammonium chloride), TMAdaI (N,N,N-trimethyl adamantylammonium iodide), TEAOH (tetraethylammonium hydroxide), TEABr (tetraethylammonium bromide), TEAF (tetraethylammonium fluoride), TEACl (tetraethylammonium chloride), TEAI (tetraethylammonium iodide), dipropylamine, and cyclohexylamine.

[0080] The hydrothermal synthesis method may be carried out for 6 hours to 400 hours and at a temperature range of 100° C. to 250° C. Specifically, the hydrothermal synthesis method may be carried out for 100 hours to 200 hours and at a temperature range of 140° C. to 180° C.

[0081] The DDR precursor solution may include SiO2, a second organic structure derivative, H2O, a sodium compound, and an aluminum compound. For example, the sodium compound may include sodium oxide or sodium hydroxide, specifically Na2O3, NaOH. The aluminum compound may include aluminum oxide or aluminum hydroxide, specifically Al2O3, Al(OH)3.

[0082] The molar ratio of each of the SiO2, second organic structure derivative, H2O, sodium compound, and aluminum compound may be 100:1 to 1000:10 to 100000:0 to 500:0 to 100. Specifically, the molar ratio of each of the SiO2, second organic structure derivative, H2O, sodium compound, and aluminum compound may be 100:10 to 800:500 to 30000:0 to 50:0 to 20, and more specifically, may be 100:450:11240:0:0.

[0083] The second organic structure derivative may be one or more of methyltropinium iodide, methyltropinium bromide, methyltropinium fluoride, methyltropinium chloride, methyltropinium hydroxide, quinuclidinium, TEAOH (tetraethylammonium hydroxide), TEABr (tetraethylammonium bromide), TEAF (tetraethylammonium fluoride), TEACl (tetraethylammonium chloride), TEAI (tetraethylammonium iodide), ethylenediamine, and adamantylamine.

[0084] The hydrothermal synthesis method may be carried out for 6 hours to 400 hours and at 100°C to 250°C, specifically, the hydrothermal synthesis method may be carried out for 12 hours to 300 hours and at 100°C to 200°C.

[0085] The CHA precursor solution and the DDR precursor solution each contain Si and Al, and the CHA structure may have a Si:Al molar ratio reference value of 100:0-10, and the DDR structure may have a Si:Al molar ratio reference value of 100:0-10.

[0086] The method may further include a heat treatment step after the secondary growth step, and the heat treatment step may be performed in an ozone atmosphere at a temperature range of 100° C. to 300° C.

[0087] The heat treatment in the ozone atmosphere may be performed at a temperature lower than that of the conventional heat treatment, and the heat treatment step using the ozone atmosphere can remove the second organic structure derivative that may be present in the pores of the CHA-DDR series zeolite separation membrane. In addition, the heat treatment step according to the present embodiment is performed in a low temperature range, so that it is possible to prevent the formation of microcracks that may be generated due to the different thermal behavior between the support and the CHA-DDR series zeolite separation membrane. As a result, the separation ability of mixed gases, etc. can be further improved.

[0088] The CHA-DDR series zeolite separation membrane may contain 1-adamantylamine in an amount of 1 wt % or less inside the pores.

[0089] Hereinafter, examples of the present invention and comparative examples will be described. However, the following examples are merely preferred examples of the present invention, and the scope of the present invention is not limited to the following examples.

[0090] (Production of Examples and Comparative Examples) 1. SSZ-13 particle synthesis and SSZ-13 seed layer formation on tubular support Zeolite films were fabricated using α-alumina tubular supports (outer diameter: 1.2 cm, thickness: 0.2 cm, length: 9 cm; Korea Finetech Co., Ltd.) with asymmetric morphology and high flux. The α-alumina tubular supports consisted mostly of α-alumina with very low levels of β-alumina as an impurity. Prior to synthesizing the zeolite films, both ends (approximately 2 cm) of the α-alumina tubular supports used for sealing cells or modules were glazed with an impermeable material (IN1001 Envision Glazes, Duncan Ceramics, USA). After completing the glaze treatment, SSZ-13 (standard oil synthetic zeolite-13, SSZ-13; chabazite (CHA) form), a zeolite containing a CHA structure, was synthesized as seed particles. The Si to Al ratio of the fabricated SSZ-13 seed particles was shown to be 20±2 on average.

[0091] The prepared SSZ-13 seed particles were coated on the outer surface of the α-alumina tubular support by a dip coating method. Specifically, the prepared SSZ-13 seed particles were added to a 250 mL polypropylene (PP) bottle containing ethanol, and then ultrasonicated for 20 minutes using an ultrasonic device (UC-10, JeioTech Co. Ltd., Republic of Korea) to prepare a suspension. The prepared suspension contained 0.75 g of seed particles per 1 L of ethanol. To apply the dip coating method, the suspension (about 50 mL) was transferred and filled into a 50 mL graduated cylinder. At this time, the α-alumina tubular support was dip coated using a dip coater (ZID-6A, Jaesung Engineering Co., Republic of Korea).

[0092] The α-alumina tubular support was moved vertically downward so as to be completely immersed in the suspension containing SSZ-13 seed particles. After immersion for about 30 seconds, the α-alumina tubular support was raised and moved to the initial position, and dried at room temperature for about 30 seconds. This dip coating was repeated a total of 14 times to form a seed layer composed of seed particles with a uniform and dense shape. Dip coating was performed 7 times in one direction of the α-alumina tubular support. Then, the α-alumina tubular support was turned over and dip coating was performed 7 times in the other direction of the α-alumina tubular support. At this time, parafilm (PM996, Bemis Co., Inc., USA) was attached to the bottom of each α-alumina tubular support to prevent the seed particles from being coated on the inner surface of the α-alumina tubular support.

[0093] After dip coating was completed, the α-alumina tubular support coated with the seed particles was separated from the dip coater and dried at room temperature for about 30 minutes.Then, the α-alumina tubular support coated with the seed particles was placed in a box-type furnace (CRF-M20-UP, Pluskolab, South Korea) and fired at 450°C for 4 hours by increasing the temperature at 1°C / min.

[0094] 2. DDR isolation film grown heteroepitaxially on SSZ-13 seed layer Zeolite containing the DDR structure (all-silica deca-dodecasil3 rhombohedral, DDR; DDR form) was synthesized as follows.

[0095] Ethylenediamine (EDA; E26266, ≥99%, Sigma-Aldrich) was placed in a PP reactor, and 1-adamantylamine (ADA; H30076, 98%, Alfa Aesar), an organic structure-directing agent (OSDA) for zeolite synthesis with a DDR structure, was added to the reactor. The PP reactor containing ethylenediamine and 1-adamantylamine was homogenized by ultrasonication for 20 minutes. After ADA was completely dissolved in EDA, deionized water (DI) was quickly added to the mixture. Immediately after adding DI water to the PP reactor, the solution became opaque and a suspension was formed. The suspension was then mixed for 1 hour using a shaker machine (Si-300R, JeioTech Co. Ltd., Republic of Korea). After mixing was completed, the suspension was placed in an oil bath heated to about 95°C and stirred using a magnetic bar for 3 hours until the opaque mixture became transparent. After heating to about 95°C, the PP reactor was removed from the oil bath and cooled in a bath filled with ice water. During cooling, the solution was stirred using a magnetic bar for about 20 minutes. Fumed silica (CAB-O-SIL M5, Cabot Corp., USA) was then added to the cooled mixture. The mixture was further mixed at room temperature for 12 hours using a shaker machine. The final molar composition of the DDR synthesis precursor thus prepared was 100:47:404:11240 (SiO2:ADA:EDA:H2O).

[0096] About 90 mL of the DDR synthesis precursor was added to a Teflon liner (total volume: about 120 mL). Then, the α-alumina tubular support coated with the seed particles was placed inclined in the Teflon liner. The Teflon liner was placed in an autoclave made of stainless steel and sealed. The autoclave was transferred to a convection oven (PL_HV_250, Pluskolab, Republic of Korea) preheated to 160 °C to carry out the hydrothermal synthesis under static conditions. After running for a day, the autoclave was quenched with tap water to interrupt the hydrothermal synthesis. After cooling the autoclave, the zeolite film sample synthesized on the tubular support was taken out and placed in a 500 mL beaker filled with deionized water and washed for 12 hours. The sample was then placed in a dry oven (HB-502M, Pluskolab, Republic of Korea) at 70 °C to dry.

[0097] The dried tubular zeolite films were heat-treated by two methods: (1) air heat treatment, which was performed in a box furnace with a heating rate of 0.2 °C / min, followed by heat treatment at 550 °C and 200 mL / min air stream for 12 h, and (2) ozone heat treatment, which was performed in a quartz tube (outer diameter 50 mm, wall thickness 2 mm) in a tubular furnace (Scientech, Republic of Korea) with a heating rate of 0.2 °C / min, followed by heat treatment at 250 °C and 200 mL / min ozone (O3) stream for 40 h. In this case, the ozone stream was configured to contain 5 vol% ozone to balance the pure oxygen, and in particular, the ozone stream was generated by flowing pure oxygen gas (99.9% purity) at a rate of 1000 mL / min in an ozone generator (OZE-020, Ozone Engineering Co., Ltd., Republic of Korea). Here, the manufactured tubular zeolite film form is called a CD separation membrane, which means a DDR zeolite separation membrane heteroepitaxially grown from a SSZ-13 (CHA type) seed layer.

[0098] 3. Synthesis of DDR@CHA hybrid particles SSZ-13 zeolite particles were used as seed particles, and DDR-structured zeolite (all-silicaDDRzeolite) was synthesized on the DDR synthesis precursor by heteroepitaxial growth. The DDR synthesis precursor was the same as the precursor used to synthesize the tubular zeolite film, the CD film.

[0099] The DDR synthesis precursor (about 30 mL) was placed in a Teflon liner (total volume: about 45 mL) to which SSZ-13 seed particles (about 0.03 g) were added. The Teflon liner was placed in a stainless steel autoclave and sealed. The stainless steel autoclave was placed in a convection oven preheated to 160° C. The autoclave was rotated at about 45 rpm for 2 days to allow the seed particles to grow. The stainless steel autoclave was then quenched using tap water to terminate the growth of the seed particles.

[0100] After cooling the stainless steel autoclave, the synthesized particles were collected using a centrifuge (Combi-514R, Hanil Scientific Industries Co., Ltd., Republic of Korea). The synthesized particles were subjected to centrifugation, decanting, and washing with deionized water five times. The solid product obtained in this manner was dried in a dry oven at 70°C.

[0101] The dried particles, as in the above CD separation membrane, were thermally activated by carrying out the following two heat treatments. The heat treatments were divided into (1) air heat treatment, in which the temperature was increased at 1°C / min in a box furnace, and the particles were heated at 550°C and 12 hours with an air stream of 200mL / min, and (2) ozone heat treatment, in which the temperature was increased at 1°C / min in a tubular furnace (Scientech, Republic of Korea), and the particles were heated at 250°C and 40 hours with an ozone (O3) stream (5 vol% ozone) of 200mL / min. For convenience, the hybrid particles thus produced are referred to as CD-P, where C and D represent DDR zeolites heteroepitaxially grown from CHA-type seed particles and CHA zeolite seed particles, respectively, and P was added to distinguish them from the above film morphology.

[0102] 4. Characterization SEM images were confirmed using a field emission scanning electron microscope (FE-SEM; S-4800, Hitachi Ltd., Japan). Prior to obtaining SEM images, the powder and separation membrane samples were each coated with Pt using an E-1045 ion sputter (generated at 30 mA for 30 seconds) (Hitachi Ltd., Japan).

[0103] X-ray diffraction (XRD) patterns were confirmed using a D / Max-2500V / PC X-ray diffractometer (Rigaku Co., Japan) with CuKα radiation (λ = 0.154 nm). For accurate comparison, the simulated XRD patterns of CHA and DDR zeolites were confirmed using Mercury software (downloadable at the Cambridge Crystallographic Data Center website, http: / / www.ccdc.cam.ac.uk). The respective crystal information files were available for download at the IZA (International Zeolite Association) website (http: / / www.iza-online.org).

[0104] Thermogravimetric analysis (TGA) results of CD-P particles were also obtained in an air environment using a Q50 (TA Instruments, USA).

[0105] To investigate the structural properties of the heteroepitaxially grown CD membrane, cross-sectional specimens were prepared using a dual beam-focused ion beam scanning electron microscope (DB-FIB SEM; LYRA3 XMH, Tescan Orsay Holding, Czech Republic). Before cutting the cross-sectional specimens using DB-FIB SEM, the outer surface of the CD membrane was sequentially coated with carbon and platinum (Pt) to prevent beam damage. Then, a very thin cross-sectional specimen with a thickness of about 100 nm was prepared using the gallium ion beam of DB-FIB SEM for transmission electron microscopy (TEM) measurements. Cross-sectional TEM images, scanning transmission electron microscopy (STEM) images, and STEM-energy dispersive X-ray (EDX) data were obtained using the fabricated cross-sectional specimens. The CHA structure (seed particle) and DDR structure (grown on seed particle) zeolite regions were identified using the STEM microprobe mode. For this purpose, an FEI XFEG-Titan themis3 Double Cs & Monochromated TEM (Thermo Fisher Scientific Inc., USA) was used.

[0106] Fluorescence confocal optical microscopy (FCOM) was used to confirm the internal defect structure of the hybrid CD separation membrane prepared by heat treatment in air and ozone environments. FCOM images of the hybrid CD separation membrane were obtained with an LSM700 confocal microscope (Carl-Zeiss, Germany) using a solid-state laser (555 nm wavelength). The CD separation membrane samples were stained with fluorescein sodium salt (F6377, Sigma-Aldrich) as a dye molecule. The size of the dye molecule is approximately 1 nm, and it is expected to selectively approach non-zeolite defects, while the size of the dye molecule is approximately 0.01 nm, which .... 2 It was confirmed that the fine pores of the cellulose acylate were maintained without being damaged.

[0107] Before FCOM measurement, the tubular CDs separation membranes prepared by air heat treatment and ozone heat treatment were crushed into small pieces. Then, the prepared samples were stained by immersing them in 1 mM sodium fluorescein aqueous solution for about 4 days. After the staining was completed, the FOCM images of the stained tubular CDs separation membranes were confirmed according to the thickness of the separation membrane. The obtained FOCM images were further processed to visually reconstruct the 3D defect structure. 5.Separation performance measurement To measure the separation performance of the hybrid CD membrane, the total pressure of the feed and permeate was kept at about 1 bar and 0.03 bar, respectively, and the separation performance for CO2 / CH4 and CO2 / N2 mixed gases was confirmed. A vacuum pump (DTC-22B, Ulvac Technologies Inc., Japan) was used to keep the pressure low on the permeate side. To compare the separation performance, one CD membrane was installed in a permeation cell (CD-1-Cell) and four CD membranes were installed in a permeation module (CD-4-Module). Figure 2 shows the schematic configuration of the cell and module for the separation performance evaluation. Figure 2 shows (a) one CD membrane installed cell (CD-1-Cell) and (b) four CD membrane installed module (CD-4-Module) for checking the permeability evaluation and gas flow in the CO2 / CH4 separation process.

[0108] The cells and modules used to measure the separation performance were custom-made (Finetech Co., Ltd., Republic of Korea). The partial pressure of the CO2 / CH4 binary mixture was approximately 50.5 kPa:50.5 kPa (DRY CO2:CH4 = 50:50) under dry conditions, and the partial pressure of the CO2 / N2 binary mixture was approximately 15.2 kPa:85.8 kPa (DRY CO2:N2 = 15:85) under dry conditions. Separation performance was also evaluated under wet conditions. The partial pressures of the ternary mixtures of CO2 / CH4 / H2O and CO2 / N2 / H2O were approximately 49 kPa:49 kPa:3 kPa (WET CO2:CH4 = 50:50 and WET CO2:N2 = 50:50) and approximately 14.7 kPa:83.3 kPa:3 kPa (WET CO2:N2 = 15:85), respectively.

[0109] The separation performance for CO2 / CH4 and CO2 / N2 was confirmed at 50°C and with the relative humidity varied from 26% to 100%. Under both dry and wet conditions, the molar compositions of the binary mixtures of CO2 / CH4 and CO2 / N2 were 50% CO2 / 50% CH4 and 15% CO2 / 85% N2, respectively, based on the dry state.

[0110] Using a thermal mass flow controller (F-201CL, Bronkhorst, The Netherlands), the total supply flow rate was changed from 25 mL / min to 1000 mL / min for the CD-1-Cell, and from 100 mL / min to 4000 mL / min for the CD-4-Module, and the recovery rate and purity were confirmed to confirm the separation performance of the CD separation membrane.

[0111] The logarithmic mean pressure drop was used to calculate the permeability considering the concentration gradient in the axial direction of the tubular CD separation membrane. The CD-1-Cell and CD-4-Module were placed in an oven (DX330, Yamato Scientific Co., Ltd., Japan) and the separation performance of CO2 / CH4 and CO2 / N2 was confirmed at various temperatures. Next, the molar composition of molecules on the permeate side was analyzed using gas chromatography (YL6500 GC, Youngin Chromass, Korea). A vacuum pump was used to continuously inject molecules on the permeate side into the gas chromatography equipped with a thermal conductivity detector (TCD). For precise measurement, N2 (ca. 10 mL / min) was used as the internal standard for CO2 / CH4 separation performance and CH4 (ca. 10 mL / min) was used for CO2 / N2 separation performance.

[0112] (Evaluation Results of Examples and Comparative Examples) 1. Characteristics of heteroepitaxially grown DDR@CHA separator FIG. 3 shows an SEM image, an XRD pattern, a STEM image, and an XRD pattern of the CD separator according to this embodiment.

[0113] Figure 3 shows (a) SEM images of SSZ-13 seed particle-coated tubular α-Al2O3 support, (b) DDR membrane (i.e., ozone-heat-treated CD membrane, or CD membrane) heteroepitaxially grown on SSZ-13 seed layer, and (c) XRD patterns of SSZ-13 seed particle, seed layer, and CD membrane. The enlarged XRD patterns of SSZ-13 seed layer and CD membrane are shown in normalized XRD patterns. The simulated XRD patterns of CHA zeolite and DDR zeolite are shown at the top and bottom, respectively. In (c), * and dagger symbols (†) indicate the XRD peaks of the support composition consisting of α-Al2O3 (majority) and β-Al2O3 (trace), respectively. (d) shows the cross-sectional TEM image of the FIB-processed CD membrane and the chemical composition for (e) Al (gray) and (f) Si (white) and Al (gray). The images for the chemical composition are for the dotted rectangle in (d). The arrows in (d)-(f) indicate the SSZ-13 seed particles in the CD membrane. The white and gray rectangles in (f) indicate the corresponding ratios of Si and Al, respectively. (g) shows the cross-sectional STEM image of the sample shown in (d), and (h) and (i) show the XRD patterns obtained for the open circles shown in (h) and (i) in (g). In (h) and (i), it was confirmed that the diffraction pattern (shown as dots) measured by the

[0110] zone axis of the DDR zeolite was superimposed with the pattern obtained in the experiment. In (i), the diffraction pattern corresponding to the CHA zeolite is shown as a gray dot.

[0114] It was confirmed that SSZ-13 (CHA type) seed particles with a particle size of about 230 nm were uniformly coated on the outer surface of the asymmetric α-Al2O3 tubular support by dip coating (Figure 3(a)). It was confirmed by XRD analysis that a CHA zeolite seed layer was formed (Figure 3(c)). Next, the CHA seed layer was heteroepitaxially grown using a synthetic precursor that enables DDR zeolite synthesis. The ozone heat-treated CD separation membrane was shown in a continuous diamond shape (or pyramid shape) in the SEM image (Figure 3(b)), and the XRD analysis of the corresponding part confirmed that it was mostly composed of DDR zeolite (Figure 3(c)). In particular, it was confirmed that the pyramidal spike-like shape in Figure 3(b) is similar to the particle shape of pure DDR zeolite. It was confirmed that the XRD peak of the (101) plane corresponding to CHA zeolite appeared even after DDR zeolite grew on the CHA seed layer (Figure 3(c)). Hereinafter, the heteroepitaxially grown zeolite membrane will be referred to as a CD membrane, and C and D represent hybrid membranes such as CHA zeolite and DDR zeolite, respectively.

[0115] To confirm the heteroepitaxially grown structure, a cross-sectional sample with a thickness of about 100 nm was prepared and TEM analysis was performed. The cross-sectional TEM image in Figure 3(d) clearly showed the presence of two distinct regions in the CD separation membrane with a total thickness of about 2 um. Specifically, some spherical particles (indicated by the arrow in Figure 3(d)) were mainly observed at the interface between the α-Al2O3 support and the CD separation membrane. Also, in Figures 3(e) and (f), the chemical composition (same area as the dotted square in Figure 3(d)) showed a higher Al content than the area that appeared to be grown from the particles. In particular, the Al-rich region of the CD separation membrane appeared similar to the CHA seed particles in terms of the Si to Al ratio (Si / Al = 20 ± 2) and the pattern and size (Figures 3(a), (d) to (f)). Meanwhile, the area between and above the Al-rich region appeared to be highly siliceous, as if grown by the DDR zeolite synthesis precursor.

[0116] The STEM image of the CD membrane was confirmed (Figure 3(g)). The uniformly appearing part was mainly observed on the top of the CD membrane, and the dark spots were mainly observed at the interface, which was consistent with the TEM image in Figure 3(d). For the part marked with a white circle in Figure 3(g), the XRD pattern was confirmed based on the STEM microprobe mode. This confirmed the irregularly grown membrane (see Figure 3(h) which is an enlarged view of the part marked with h in Figure 3(g), excluding the dark spots) and the seed particles (the part marked with i in Figure 3(g), dark spots). In particular, based on the STEM microprobe mode, the electron beam was able to analyze various regions with high spatial resolution (approximately 50 nm accuracy). The XRD patterns in Figure 3(h) and (i) were interpreted to confirm the crystal structures of h and i in the STEM image (Figure 3(g)). It was confirmed that these represent the secondary grown DDR zeolite and CHA seed particles, respectively.

[0117] 4 shows a STEM image and an electron diffraction pattern of the CD separator according to this example, and FIG. 5 shows an electron diffraction pattern for the indicated portion of the STEM image in FIG.

[0118] In Fig. 4, (a) shows a STEM cross-sectional image (same as Fig. 3g) and (b) shows the electron diffraction pattern at the part indicated as c1 in (a). The parts indicated as a1 and b1 in (a) are respectively the same as the parts indicated as h and i in Fig. 3g, which are shown in Fig. 3h and (i), respectively. The parts indicated as black circles in white circles in (b) correspond to the (003), 110, and (113) planes of DDR zeolite on the

[0110] zone axis. The parts corresponding to CHA zeolite correspond to the (121), 101, and (213) planes on the

[0111] zone axis.

[0119] In Figure 5, (a1) to (c1) show the experimental values ​​of the electron diffraction patterns for the parts corresponding to a1, b1, and c1 in Figure 4(a). (a2), (b2), and (c2) show the DDR zeolite, and (a3), (b3), and (c3) show the simulation results for CHR zeolite. To compare the experimental values ​​and the simulation results, they are arranged in Figure 5 so that they correspond to each other.

[0120] The electron diffraction pattern confirmed the DDR zeolite with a <0110> zone axis. An additional electron diffraction pattern appeared at position i, where it was confirmed that the <0110> zone axis for the DDR zeolite was weakly present. The additional electron diffraction pattern was found to originate from CHA zeolite, as it could not be explained by any plane of the DDR zeolite (in particular, the point near the center corresponds to the (101) plane that mainly appears in CHA zeolite). Moving further to the center of the dark spot at position i, an additional electron diffraction pattern was confirmed that did not correspond to the DDR zeolite (see FIG. 5). This confirmed the appearance of some additional points on the <0111> zone axis of the CHA zeolite matrix.

[0121] Referring to (h) and (i) of FIG. 3, FIG. 4, and FIG. 5, the electron diffraction pattern results according to the experimental results could also be confirmed by the simulated electron diffraction pattern. Although the electron diffraction patterns of DDR zeolite and CHA zeolite could not be completely separated, the newly appeared X-ray electron diffraction patterns (i.e., "a1" to "c1" of FIG. 5) due to CHA zeolite could be confirmed close to the dark spots, which means that CHA zeolite and DDR zeolite coexist. In other words, it was confirmed that DDR zeolite can be heteroepitaxially grown on the CHA seed layer with structural compatibility, and as a result, the upper and lower regions of the separation membrane are divided into DDR zeolite and a mixed layer of DDR zeolite and CHA zeolite, respectively.

[0122] 2. Characteristics of DDR@CHA hybrid particles FIG. 6 shows SEM images and XRD patterns of CD-P particles according to the heat treatment conditions of the embodiment of the present invention. In FIG. 6, (a) SEM images of as-synthesized, (b) air-calcined, and (c) ozone-calcined are shown. (d) shows XRD patterns of CD-P as-synthesized, air-calcined, and ozone-calcined. Simulated XRD patterns of CHA zeolite and DDR zeolite are shown at the top and bottom, respectively. (e) shows the particle size distribution of ozone-calcined CD-P, which appears in the form of diamond, and the longest length of each particle was measured. (f) shows the TGA results of CD-P as-synthesized, air-calcined, and ozone-calcined. When measuring the TGA, the temperature was raised to 110°C at room temperature in air, held at 110°C for 3 hours, and then further raised to 800°C. During this time, the temperature was increased at a rate of 1°C / min.

[0123] In order to determine the heat treatment conditions for the synthesized CD film, the CD-P particles were used for TGA analysis. The same seed particle growth method was used for the synthesis of the CD separator and the CD-P particles, so the TGA results of the CD-P particles can be used as the basis for determining the heat treatment conditions for the CD separator. Here, "as-synthesized" means the state before heat treatment. The synthesized CD-P particles were subjected to air heat treatment and ozone heat treatment, respectively. Figure 6 shows that the diamond pattern of the CD-P particles is preserved regardless of the heat treatment conditions. It was also confirmed that it matches the surface morphology of the CD separator. It was confirmed that the CD-P particles heat-treated at 550°C and air and the CD-P particles heat-treated at 250°C and ozone had the same XRD pattern as the simulated XRD pattern of the DDR zeolite in Figure 6(d). This means that the synthesized CD-P particles are mostly composed of zeolite with a DDR structure.

[0124] The average particle size of the ozone heat-treated CD-P particles was 2.9±0.7um. Considering that the thickness of the hybrid CD separation membrane was about 2um, which is similar to the particle size of the CD-P particles, the properties of the CD-P particles are expected to be the same as those of the hybrid CD separation membrane. From the TGA results of the CD-P particles (i.e., the synthesized CD-P particles and the CD-P particles heat-treated under air and ozone conditions), it was confirmed that the ADA present inside the CD-P particles was completely removed by the heat treatment.

[0125] For more detailed analysis, the water adsorbed on the zeolite particles was removed by heat treatment at 110°C for 3 hours. First, the TGA results of the synthesized CD-P particles showed that the weight fraction of ADA (ca. 10.8 wt%) was similar to the theoretical value (ca. 11 wt%). This means that most of the CD-P particles were composed of zeolite with a DDR structure. In addition, the TGA results of the air heat-treated and ozone heat-treated CD-P particles showed that ADA was completely removed after the synthesized CD-P particles were heat-treated at 550°C and air conditions (air heat-treatment) or 250°C and ozone conditions (ozone heat-treatment). This means that the two heat-treatment methods can be used appropriately for the synthesized CD separation membrane.

[0126] By the above air heat treatment at 550℃ or ozone heat treatment at 250℃, ADA was effectively removed by both methods. Meanwhile, in the case of zeolite separation membranes synthesized at high temperatures, defects were formed due to the difference in thermal expansion behavior between the zeolite separation membrane and the α-alumina support by heat treatment. As a result, the permeation selectivity of the prepared zeolite separation membrane was reduced (here, CO2 / CH4SF1.8 at 30℃ under dry conditions). Therefore, permeation measurements were performed only on the ozone heat-treated CD separation membrane. The zeolite pores of the CD film were thermally activated at a relatively low temperature of 250℃ with almost no defects, and showed high separation performance.

[0127] 3. Defective structure of CD separation membrane Figure 7 shows SEM and FCOM images of the CD membranes after air and ozone heat treatments. In Figure 7, the images of the CD membranes after air heat treatment (air-calcined, (a1)-(a3)) and ozone heat treatment (ozone-calcined, (b1)-(b3)) are shown. (a1) and (b1) are cross-sectional FCOM images, (a2) and (b2) are FCOM images of the upper part, and (a3) ​​and (b3) are SEM images of the upper part. The cross-sectional FCOM images correspond to the dotted part of the upper FCOM. The dotted line in the cross-sectional FCOM images indicates the position of the upper FCOM image. In (a1) and (b1), the upper and lower white dotted lines indicate the outer surface of the CD membrane (upper part) and the interface between the CD membrane and α-Al2O3 (lower part), respectively. In (a2), the arrows indicate cracks observed in the cross-sectional FCOM. To confirm the effects of air heat treatment (a4) and ozone heat treatment (b4), tilted plan view 3D images generated by image processing using FCOM images are shown. Unlike (a4), in (b4), pixels corresponding to defects were not detected and extracted by FCOM image processing, so it is marked as "Non-Detectable."

[0128] In the process of heat-treating a zeolite separation membrane at a high temperature, defective structures such as microcracks may be formed in the zeolite separation membrane. Such microcracks often act as non-selective pathways in the process of separating mixed gases, and may therefore reduce the permeability selectivity of the separation membrane. This occurs because the thermal behavior of the zeolite separation membrane and the α-Al2O3 support is different during the heat-treating process at a high temperature. Meanwhile, in this embodiment, the ozone heat treatment is performed at a relatively low temperature, thereby preventing the formation of such defects in the separation membrane.

[0129] Figure 8 shows SEM images of the CD separator under different heat treatment conditions, where (a1) and (b1) are top surface SEM images, and (a2) and (b2) are cross-sectional SEM images.

[0130] The particle-shaped CD-P (here, C is CHA seed particle, D is DDR zeolite grown secondary after the growth of CHA seed particle, and P is particle-shaped) produced by the above method was used for the experiment. 1-adamantylamine (ADA), which was used as an organic structure-directing agent (OSDA) for the seed particle growth of CD and CD-P, was removed by air heat treatment and ozone heat treatment. In particular, CD-P was produced under similar synthesis conditions to the CD separation membrane, and it was confirmed that the particle size of CD-P appears to be similar to the thickness of the CD separation membrane. Therefore, the results of air heat treatment and ozone heat treatment confirmed in CD-P were applied to the CD separation membrane and confirmed.

[0131] FCOM analysis was used to visually confirm the defect structure of the CD separator after air heat treatment and ozone heat treatment. Air heat treatment was performed at high temperature, and it was confirmed that the CD separator after air heat treatment had a network of microcracks, which are interconnected defect structures. This network of microcracks was connected to the interface between the separator and the α-Al2O3 support. The defect structure appeared to be similar to that of the homogeneous DDR and heteroepitaxially grown DDR@CHA separator based on MTI. On the other hand, the CD separator after ozone heat treatment, which was performed at a relatively low temperature, did not show any defects.

[0132] The air-heat-treated and ozone-heat-treated CD separators appeared similar in SEM images (Figure 7 (a3) ​​and (b3)), but the FCOM images showed significant differences in defect structures (Figure 7 (a1), (a2), (b1), and (b2)). For specific analysis, the FCOM images were processed into 3D images to confirm the defect structures (Figure 7 (a4) and (b4)). It was confirmed that the air-heat-treated CD separator showed clear defect structures, while the ozone-heat-treated CD separator showed almost no defect structures.

[0133] 4. Evaluation of separation performance of CD membrane from the viewpoint of separation membrane Figure 9 shows the results of CO2 / CH4 separation performance of CD separation membranes prepared by air heat treatment and ozone heat treatment. Referring to Figure 9, CO2 / CH4 equimolar mixture was fed at 1000mL / min flow rate and 30℃ dry and wet conditions (water vapor pressure ca. 3kPa). It was confirmed that the ozone heat-treated CD separation membrane was superior in permeability and CO2 / CH4SF compared to the air heat-treated CD separation membrane. This is because, as mentioned above, microcracks were formed in the air heat treatment, and the microcracks provide a non-selective path in the process of separating the mixed gas.

[0134] Figure 10 shows the results of evaluating the CO2 / CH4 separation performance for the CD-1-Cell and CD-4-Module. (a1) CD-1-Cell with a supply flow rate of 1000 mL / min, (b1) CD-4-Module with a supply flow rate of 4000 mL / min, and (C1) CD-4-Module with a supply flow rate of 1000 mL / min, were used to measure the CO2 / CH4 equimolar mixture under dry and wet conditions (ca. 3 kPa), respectively. The temperature ranges related to biogas are shaded in (a1) and (c1). (a2) CD-1-Cell with 1000 mL / min feed flow rate, (b2) CD-4-Module with 4000 mL / min feed flow rate, and (c2) CD-4-Module with 1000 mL / min feed flow rate were checked at various relative humidities (RH) at 50 °C, 0% (dry), ~26%, ~60%, and ~100% (corresponding to water vapor pressures of 0, ~3, ~7, and ~12 kPa, respectively), with a CO2 / CH4 equimolar mixture as feed. After performing the humidity experiments at ca. 12 kPa in wet conditions, the samples were dried at 110 °C for 3 h and subsequently measured again at 50 °C in dry conditions.

[0135] In the case of DDR zeolite, it was confirmed that the adsorption of CO2 and CH4 follows a linear behavior, so that the composition change in the mixed gas does not have a significant effect on the permeability of each. On the other hand, it was confirmed that the separation performance of CD-4-Module decreased when the supply flow rate decreased from 4000mL / min to 1000mL / min (Figure 10 (b1) and (c1)). The decrease at low supply flow rates is considered to be due to the polarization of CO2 concentration in the radial direction (because CO2 is a fast permeating component) and / or the degree of depletion of CO2 in the bulk in the axial direction. This means that the performance of CD separation membranes is greatly affected by different supply flow rates, and it was confirmed that application of this is necessary in separation processes based on actual separation membranes.

[0136] Under wet conditions (water vapor pressure of about 3 kPa), the CO2 / CH4 separation performance of CD-1-Cell and CD-4-Module was confirmed (Figure 10 (a1) to (c1)). Water vapor is preferentially adsorbed on the external and internal surfaces of the separation membrane at low temperatures, blocking the zeolite micropores and thereby hindering the movement of CO2 molecules. The negative effect of water molecules adsorbed on the separation membrane is reduced as the temperature increases to 100°C. As a result, the CO2 permeability tends to be high and the CH4 permeability tends to be low under both dry and wet conditions at 100°C. That is, this allowed high CO2 / CH4SF to be obtained regardless of the presence or absence of water vapor.

[0137] In particular, the CD separation membrane is hydrophobic, being composed entirely of silica, and therefore, even when water molecules are adsorbed, the decrease in CO2 permeability is minimized, and the membrane has high CO2 permeability selectivity even at low temperatures. Specifically, under wet conditions, the maximum CO2 / CH4SF of CD-1-Cell was as high as 476±121 at 30°C, and even when water vapor was present in the feed over the entire temperature range up to 100°C, the CO2 / CH4SF was well maintained (Figure 10 (a1)). The typical temperature of biogas streams is 25°C to 60°C, and in particular, there is a recent trend toward biogas production at about 50°C. It was confirmed that the CO2 / CH4 separation performance measured by the CD-1-Cell according to the present invention at 50°C was very high. That is, the CO2 permeability measured by the CD-1-Cell was (5.9±0.7)×10 -7 mol m -2 ·s -1 ·Pa -1 (ca. 1770 GPU), and the CO2 / CH4SF was 383±82.

[0138] The CO2 permeability and CO2 / CH4SF measured by the CD-4-Module at 50℃ were ca. 6.4×10 -7 mol m -2 ·s -1 ·Pa -1(ca. 1900 GPU) and 268 (Fig. 10(b1)). In particular, the intrinsic CO2 permselectivity of both CD-1-Cell and CD-4-Module was excellent, exceeding 100 in the temperature range of 30℃~100℃ (Fig. 10(a1) and (b1)). This means that the CD separation membrane of the present invention can effectively purify biogas regardless of the water vapor content at various temperatures.

[0139] Even when the same CD membrane is used, the CO2 permeation selectivity may vary depending on the design of the cell or module. For example, the residual volume per membrane installed in the cell or module varies depending on the feed stream. Specifically, the empty volume allocated to one CD membrane in the CD-4-Module is about 2.5 times larger than that in the CD-1-Cell. That is, compared to the module, the cell has a smaller volume, and thus the feed stream passing through the smaller volume cell is more likely to be near the outer surface of the membrane, and at the same time, a larger amount of CO2 molecules are adsorbed on the outer surface of the membrane, which can promote molecular transport and provide a higher permeability.

[0140] The CO2 permeability selectivity of CD-1-Cell and CD-4-Module was confirmed by changing the relative humidity (approximately 26, 60 and 100%, corresponding to 3, 7 and 12 kPa) at 50 °C. As the water vapor pressure increased from 0 (i.e., DRY) to ca. 12 kPa, the CO2 and CH4 permeabilities of CD-1-Cell all decreased, which is believed to be because water molecules were mainly adsorbed and hindered molecular transport.

[0141] On the other hand, it was confirmed that the displayed CO2 permeability selectivity remained almost constant regardless of the relative humidity. Specifically, it was ca. 2.9 × 10 at saturated water vapor pressure (ca. 12 kPa at 50 °C). -7 mol m -2 ·s -1 ·Pa -1It was confirmed that the CD separation membrane was well retained without significant deactivation, which is believed to be due to its hydrophobicity.

[0142] In the CD-4-Module, the relative humidity experiment results (Figure 10(b2)) showed that the trends of CO2 and CH4 permeability versus water vapor pressure were similar to those of the CD-1-Cell. Meanwhile, at a low feed flow rate of 1000mL / min, the relative humidity experiment results showed that the CO2 permeability was similar in both dry and wet conditions in the CD-4-Module. This is because mass transfer is hindered by water molecules on the outer surface of the separation membrane at low feed flow rates.

[0143] As mentioned above, when the CD separation membranes used were all dried after the relative humidity experiment was completed and the dried separation membranes were further measured under dry conditions, it was confirmed that the separation performance of both CD-1-Cell and CD-4-Module was restored (Figure 10 (a2)~(c2)). This means that high CO2 permeability selectivity is maintained regardless of the amount of water vapor up to the saturated water vapor pressure (about 12 kPa) at 50℃, which is similar to the actual biogas stream.

[0144] Figure 11 shows the results of confirming the long-term stability of CD-1-Cell.

[0145] In Figure 11, the measurement was performed under wet conditions (saturated vapor pressure ca. 12 kPa) with a feed flow rate of 100 mL / min using a CO2 / CH4 equimolar mixture as the feed, and was performed at 50°C for up to 4 days. In the middle of the measurement, it was additionally confirmed that the measurement was performed at 200°C for up to 2 days. After confirming the long-term stability under wet conditions (saturated vapor pressure ca. 12 kPa), the separation performance was further confirmed under dry conditions at 50°C, after which the separation performance was confirmed.

[0146] Referring to Figure 11, it was confirmed that the separation performance of CD-1-Cell was maintained when a long-term stability experiment was carried out under saturated water vapor pressure conditions at 50°C. In the present invention, even though a harsh treatment at 200°C for 48 hours was included in the middle to accelerate the decomposition degree, it was confirmed that the CO2 permeability selectivity under the original dry conditions at 50°C and 12 kPa was restored after drying. This means that the CD separation membrane according to the present invention is sufficiently robust and can be easily applied in practical use.

[0147] As mentioned above, the air heat-treated CD separator has microcracks, which are defective structures, formed inside it due to the high temperature heat treatment. Therefore, the separation performance may be reduced due to the microcracks during the process of separating mixed gases. On the other hand, the ozone heat-treated CD separator does not have defective structures, and it was confirmed that it shows better performance when separating mixed gases than the air heat-treated CD separator.

[0148] Then, CD-1-Cell (Fig. 2(a)) and CD-4-Module (Fig. 2(b)) were manufactured using the ozone heat-treated CD separation membrane, and the CO2 / CH4 separation performance was confirmed under conditions similar to actual use. In both CD-1-Cell and CD-4-Module, it was confirmed that CO2 molecules preferentially pass through the CD separation membrane, and most CH4 molecules are unable to pass through the CD separation membrane and remain behind.

[0149] The separation performance was also confirmed under wet conditions for CD-1-Cell and CD-4-Module. Dry conditions are indicated as DRY, and wet conditions as WET. Under dry conditions for CD-1-Cell and CD-4-Module, the maximum CO2 / CH4SF values ​​were high at 30℃, 498±93 and 300, respectively. In addition, CD-1-Cell, which had the highest CO2 permeability at 30℃, was (1.2±0.1)×10 -6 mol m -2 ·s -1 ·Pa -1(ca. 3440 GPUs (gas permeance units)), and the CD-4-Module is ca. 1.0 × 10 -6 mol m -2 ·s -1 ·Pa -1 In particular, as temperature increased, the permeabilities of CO2 and CH4 molecules decreased monotonically, respectively, and remained nearly constant, while the CO2 / CH4SF ratio decreased monotonically.

[0150] Figure 12 shows the permeability and SF of a CO2 / CH4 equimolar mixture for multiple CD separation membranes. In Figure 12, measurements were taken at 1000mL / min supply flow rate, 30℃, and dry conditions. It was confirmed that the separation performance of the CD separation membrane corresponds to that of the CD-1-Cell system and the CD-4-Module system.

[0151] The CO2 / CH4 separation performance was confirmed under dry conditions at 30℃. To ensure the reliability of the results, multiple membrane samples were used under each firing condition to confirm the separation performance. The ozone heat-treated CD separation membrane showed excellent CO2 permeability under dry conditions. This is believed to be because there are no membrane defects during ozone heat treatment.

[0152] Figure 13 shows the separation performance of CD-1-Cell for CO2 / N2 mixtures. (a) shows the permeability and SF as a function of temperature for CO2 / N2 two-phase mixtures (15% CO2 and 85% N2) fed to CD-1-Cell at a feed rate of 1000 mL / min under dry and wet conditions (ca. 3 kPa). In (a), the temperature range of post-combustion flue gas generated in a coal-fired plant was set. (b) shows the separation performance for CO2 / N2 mixtures fed to CD-1-Cell at feed rates of 1000 mL / min and 100 mL / min, respectively, at 50 °C, and at various relative humidities (RH), 0% (dry), ~26%, ~60%, and ~100% (corresponding to water vapor pressures of 0, ~3, ~7, and ~12 kPa, respectively). After conducting humidity experiments under wet conditions (ca. 12 kPa), the samples were dried at 110 °C for 3 h, and then further tested for separation performance under dry conditions at 50 °C.

[0153] Figure 14 shows the separation performance of CD-1-Cell for CO2 / N2 mixture under dry and wet conditions. (a1) shows the permeability and SF of CO2 / N2 two-phase mixture under dry conditions and at 30°C, and (b1) shows the permeability and SF of CO2 / N2 two-phase mixture under wet conditions (ca. 3 kPa) and at 50°C, respectively, for the feed (15% CO2 and 85% N2). The CO2 recovery rate (circles) and purity (triangles) on the permeate side of CD-1-Cell are shown, respectively.

[0154] The CO2 / N2 separation performance results of CD-1-Cell for post-combustion flue gas stream (15% CO2 and 85% N2) were confirmed. The CO2 permeability selectivity of CD-1-Cell was measured at a flow rate of 1000 mL / min for both dry and wet conditions (Figure 13(a)). Under dry conditions, the maximum CO2 permeability and CO2 / N2SF were approximately 1.0 × 10 at 30 °C, respectively. -6 mol m -2 ·s -1 ·Pa -1(ca. 3000 GPU) and 18.0 ± 0.6. At wet conditions, the maximum CO2 / N2SF occurred at 30 °C, about 26.7 ± 1.7. At dry conditions, the maximum CO2 permeability occurred at 50 °C (a typical temperature for post-combustion flue gas streams in coal-fired power plants), about 5.1 × 10 -7 mol m -2 ·s -1 ·Pa -1 (ca. 1540 GPU), and at the same temperature the CO2 / N2SF was 19.4 ± 0.6.

[0155] In general, the trends in CO2 permeability as a function of temperature under dry and wet conditions were similar to those observed for equimolar CO2 / CH4 separation performance. On the other hand, the 8-membered-ring DDR zeolite (0.36 × 0.44 nm 2 The molecular sieving effect of the SF600 is evident in the CO2 / CH4 separation performance, as the kinetic diameter of the CH4 molecule (0.38 nm) is slightly larger than that of the N2 molecule (0.364 nm). Therefore, the permeability of N2 is higher than that of CH4, and the permeability of CO2 / N2SF is lower than that of CO2 / CH4SF.

[0156] In addition, the CO2 / N2 separation performance of the CD-1-Cell was confirmed at 50°C for two supply flow rates of 100mL / min and 1000mL / min, respectively, while varying the relative humidity (relative humidity of 0%, ~26%, ~60%, and ~100%, corresponding to water vapor pressures of 0, ~3, ~7, and ~12kPa) (Figure 13(b)). As the water vapor pressure increased, water molecules were adsorbed on the CD-1-Cell, and the adsorbed water molecules reduced the mass transport, resulting in a decrease in the CO2 and N2 permeabilities. In particular, at a supply flow rate of 100mL / min, which is lower than that of 1000mL / min, the CO2 and N2 permeabilities decreased. On the other hand, at a high supply flow rate, the CO2 permeability of the CD separation membrane was well maintained at about 44% of the CO2 permeability under dry conditions, even in a saturated water vapor state of 12kPa at 50°C.

[0157] The difference in the degree of decrease is believed to be due to the difference in the amount of water vapor contacting the outer surface of the separation membrane at the different feed flow rates: as the feed flow rate is decreased, the amount of water molecules transferred to the outer surface of the separation membrane in the feed stream is decreased, thereby decreasing the inhibitory effect of the water vapor.

[0158] When comparing the effect of relative humidity on CO2 / CH4 separation performance, CO2 / N2SF monotonically increased as the relative humidity increased at both low and high feed flow rates. The increased CO2 / N2SF under wet conditions shows that the effect of adsorbed water molecules is more pronounced in the transport of N2 molecules (0.364 nm) than in the transport of CH4 molecules (0.38 nm), which is due to the DDR zeolite (0.36 × 0.44 nm). 2 This is because the permeability was already very low under dry conditions due to the molecular sieve performance of the hybrid CD membrane. In particular, CO2 / N2SF was high at 11.4 and 21.9 for feed flow rates of 100mL / min and 1000mL / min, respectively, at 50℃ and 12kPa saturated steam. It was confirmed that under the actual conditions of CO2 / CH4 separation performance and wet conditions, and feed flow rate including CO2, the hydrophobic hybrid CD separation membrane shows higher performance when steam is present as a feed.

[0159] In addition, CO2 / N2 separation performance was confirmed for various feed flow rates (25-1000mL / min) under dry conditions of 30℃ and wet conditions (ca.3kPa) of 50℃ (representative temperature of post-combustion flue gas flow). Referring to Figure 14 (a1) and (b1), the tendency of CO2 / N2 separation performance was similar to that of CO2 / CH4 separation performance under dry and wet conditions. Specifically, it was confirmed that under dry and wet conditions, CO2 permeation selectivity increased as the feed flow rate increased to about 200-300mL / min, and then reached some asymptotic values ​​at higher feed flow rates. The only difference between the dry and wet conditions shown in Figure 14 (a1) and (b1) is that the CO2 permeability decreased due to adsorbed water molecules.

[0160] The CO2 recovery and purity (representing module or process characteristics) of CD-1-Cell at various feed flow rates are shown in Figure 14 (a2) and (b2). As the feed flow rate increased, the CO2 purity increased while the CO2 recovery decreased under both dry and wet conditions. This was similar to the trend observed in CO2 / CH4 separation under dry and wet conditions. Meanwhile, the recovery and purity results for CO2 / N2 separation appeared slightly different from CO2 / CH4 separation.

[0161] As a result of checking the total supply flow rate, CO2 / N2SF appeared to be lower than CO2 / CH4SF, and the CO2 purity in CO2 / CH4 separation was above 90% for all total supply flow rates under both dry and wet conditions.As the supply flow rate increased from 25 to 1000mL / min, the CO2 purity in CO2 / N2 separation increased from 22.5% to 75.3% under dry conditions and from 29.6% to 77.0% under wet conditions, and it was confirmed that after the supply flow rate reached 300 to 400mL / min, it reached an asymptotic value of about 70% to 77%.

[0162] That is, the CD separation membrane was able to maintain a CO2 purity of over 60% at a feed flow rate of 200mL / min. Also, the amount of CO2 molecules in the feed for CO2 / N2 separation (15%) was lower than that for CO2 / CH4 separation (50%), and the amount of recovered CO2 molecules appeared to be nearly 100% at low feed flow rates. On the other hand, as the feed flow rate increased, the CO2 recovery rate decreased, confirming that the recovery rate of fast permeable components is a property related to the inherent properties of the separation membrane (diffusion permeability through the separation membrane) and the properties of the feed flow (transfer of material from the bulk to the outer surface of the separation membrane).

[0163] Referring to (a2) of FIG. 14, the CO2 / N2 separation performance achieved a simultaneous recovery rate and purity of about 60% to 70% at a supply flow rate of 200 to 300 mL / min.

[0164] Even when the crossover point of recovery rate and purity shifted to a lower feed flow rate due to the presence of water vapor, CO2 / N2SF showed improved properties under wet conditions, but CO2 molecule movement was restricted by the adsorption of water molecules.In other words, it was confirmed that separation performance should be evaluated through a comprehensive understanding that takes into account not only permeability and CO2 / CH4SF, which are properties from the perspective of the separation membrane, but also recovery rate and purity, which are properties from the perspective of the module or process.

[0165] Figure 15 shows the separation performance of CD-1-Cell for CO2 / N2 mixtures under different temperature conditions. In (a), the CO2 / N2 two-phase mixture is the feed (15% CO2 and 85% N2) and the feed flow rate is 1000 mL / min. The results are shown under dry conditions (open squares), ~3 kPa wet conditions (half-filled squares), and ~12 kPa wet conditions (fully filled squares). Robeson upper limit is shown as a black line to compare the separation performance with the polymeric separation membrane (empty circle) under dry conditions. (b) CO2 permeability and CO2 / N2SF are compared for CD-1-Cell and other zeolite separation membranes. A CO2 / N2 two-phase mixture was used as the feed (15% CO2 and 85% N2) at 50-60 °C for dry conditions (open squares), ~2-3 kPa wet conditions (half-filled squares), and ~12 kPa wet conditions (fully filled squares). Measured permeability and SF as a function of the feed flow rate.

[0166] Referring to Figure 15, the CO2 / N2 separation performance of the CD membrane was compared with polymeric membranes and other zeolite membranes under dry and wet conditions. Specifically, the types of zeolite membranes used for the comparison include (1) DDR type: ZSM-58 and c-oriented DDR, (2) CHA type: SSZ-13, dye-post-treated SSZ-13, RTP SSZ-13, CHA, CVD-treated CHA and SDA-free CHA, and (3) faujasite (FAU) type zeolite, as shown in Figure 15(b). In Figure 15(a), the CO2 / N2 separation performance of the CD membrane due to the material characteristics appears close to the Robeson upper bound, which means that it exhibits excellent performance regardless of the content of water vapor contained in the feed. As mentioned above, although the molecular size of the slow permeating components (N2: 0.364 nm vs. CH4: 0.38 nm) is not significantly different, this causes a high discrepancy in the CO2 permeation selectivity.

[0167] Although the material properties were not very good (Figure 15(a)), the CD separation membrane showed better CO2 / N2 separation performance than other zeolites in terms of CO2 permeability and CO2 / N2SF (representative separation membrane properties) (Figure 15(b)). The SSZ-13 separation membrane fabricated on a capillary tube showed high CO2 permeability similar to the CD separation membrane under dry and wet conditions, but the CO2 / N2SF was lower than that of the CD separation membrane. In addition, the FAU zeolite separation membrane showed high CO2 / N2SF (about 15) under dry conditions, but it was confirmed that when water vapor was included in the feed, the performance was significantly reduced due to preferential adsorption of water molecules over CO2. In addition, the CD separation membrane showed excellent CO2 permeability and CO2 / N2SF at 50°C and a saturated water vapor pressure of ca. 12 kPa.

[0168] 5. Evaluation of separation performance of CD membrane from module viewpoint and correlation with separation membrane properties Figure 16 shows the results of evaluating the CO2 / CH4 separation performance for CD-1-Cell and CD-4-Module. Figure 17 shows the recovery rate and purity under the dry and wet conditions shown in Figure 16.

[0169] In Fig. 16, (a1) CD-1-Cell and (b1) CD-4-Module show the measured permeability and SF as a function of the feed flow rate for the equimolar mixture of CO2 / CH4 at dry conditions (open squares), 30°C and ~3 kPa wet conditions (half-filled squares), and 30°C and ~12 kPa wet conditions (fully filled squares), respectively. (b2) and (b3) show the CO2 and CH4 recovery and purity on the permeate side and retentate side for CD-1-Cell (circles) and CD-4-Module (squares), respectively, for the CO2 / CH4 separation performances shown in (a1) and (b1).

[0170] Figure 17 shows the recovery and purity of CO2 and CH4 on the permeate and retentate sides shown in (a1) and (b1) of Figure 16. Recovery and purity are shown as a function of flow rate for the dry conditions of 30°C, 50°C and ~3 kPa wet conditions (half-filled squares), and 50°C and ~12 kPa wet conditions (fully filled squares).

[0171] Unprocessed biogas streams usually contain water vapor in the range of about 3-12% of the saturated water vapor amount, and since such water vapor has a negative effect on CO2 separation and biogas transportation, a dehydration process may be additionally performed on the raw biogas. Therefore, in this example, the CO2 / CH4 separation performance of the CD separation membrane was measured under dry conditions at 30°C and wet conditions at 50°C (about ~3 and ~12 kPa), and dried biogas streams that had been subjected to a dehydration process were used.

[0172] The separation performance was confirmed by changing the supply flow rate from 25 mL / min to 1000 mL / min for the CD-1-Cell and from 100 mL / min to 4000 mL / min for the CD-4-Module.

[0173] The membrane-based separation process was confirmed in terms of recovery and purity of CO2 on the permeate side (Figure 16 (a2) and (a3)) and CH4 on the retentate side (Figure 16 (b2) and (b3)).

[0174] In Fig. 16(a1), under dry conditions, the CO2 permeability remains almost constant at a relatively high feed flow rate, while ((1.0±0.1)×10 -6 mol m -2 ·s -1 ·Pa -1), decreased at relatively low feed flow rates of ca. 300 mL / min. In contrast, CH4 permeance increased slightly as the feed flow rate decreased. Thus, the CO2 / CH4SF decreased slightly as the feed flow rate decreased, and then decreased rapidly at feed flow rates lower than ca. 300 mL / min.

[0175] The decreased CO2 permeability at low feed flow rates is attributed to concentration polarization near the external surface of the CD membrane (i.e., radial direction) and / or the depletion of CO2 molecules along the length of the membrane (i.e., axial direction). Thus, with the depletion of CO2, CH4 molecules are adsorbed in increasing amounts on the external surface of the membrane, which leads to an increase in CH4 permeability. Notably, in the wet condition, the permeability of CO2 and CH4 was decreased mainly by water vapor. Nevertheless, the CO2 / CH4SF as a function of feed flow rate in the wet condition was similar to that in the dry condition, whereas the indicated CO2 permeability (approximately 2.9 × 10 -7 mol m -2 ·s -1 ·Pa -1 ) showed advantageous results in actual application at 50℃ and saturated water vapor pressure of 12kPa. Also, the separation performance of CD-1-Cell was similar to that of CD-4-Module in terms of feed flow rate (Figure 16 (b1)). On the other hand, at the same feed flow rate, the CO2 permeability of CD-4-Module was lower than that of CD-1-Cell and the CH4 permeability was higher than that of CD-1-Cell under dry conditions.

[0176] This difference is due to the mass transfer of CD-1-Cell and CD-4-Module, and it is considered that the mass transfer rate to the outer surface of the separation membrane is slow in CD-4-Module due to its large volume. At 50℃ and a saturated water vapor pressure of 12kPa, the separation performance was very high (Figure 16 (a1) and (b1)). At 50℃, the maximum CO2 / CH4SF of CD-1-Cell and CD-4-Module was very high at 274±73 and 189, respectively.

[0177] Similar to the high CO2 permeation selectivity of the CD-1-Cell and CD-4-Module, the respective CO2 capture rates and purity (Figure 16 (a2) and (a3)) and CH4 capture rates and purity (Figure 16 (b2) and (b3)) appeared to be approximately 100%. On the other hand, the CD separation membrane appeared to have a slightly lower CO2 capture rate at high feed flow rates, and CH4 purity at the retentate side appeared to be low due to the low CO2 capture rate. Both the dry and wet conditions showed high CO2 permeation selectivity and high CO2 purity at the permeate side (over 90% for the entire measured feed flow rates), but the CO2 capture rates decreased as the feed flow rate increased under both the dry and wet conditions.

[0178] The recovery rate and purity of CH4 on the retentate side were determined by the CO2 that preferentially passed through the CD separation membrane, and were similar to those of the CO2 recovery rate and purity on the permeate side. The CO2 permeability selectivity was maintained at a high value due to the reduced CO2 permeability caused by the adsorption of water molecules, and the CO2 recovery rate decreased as the water vapor pressure increased, while the CO2 purity was maintained at over 90%.

[0179] Increasing the number of separation membranes in a module can be effective in improving module capacity, but for optimization, correlations between module-based separation performance and dependent parameters of module configuration must be derived. Since the CO2 permeation selectivity of CD separation membranes is excellent (related to the CO2 purity at the permeate side), effective capture of CO2 can increase the purity of CH4 by increasing the module-based separation performance. Although the specific CO2 permeability and CO2 / CH4SF (which indicate the characteristics of the separation membrane) can be obtained at the highest feed flow rate (Figure 16 (a1) and (b1)), it was confirmed that the purity of CO2 (permeability through the separation membrane) and the purity of CH4 (blocked by the separation membrane and remaining in the feed) are dependent on the feed flow rate.

[0180] 6. Evaluation of separation performance of CD membrane from the viewpoints of materials, membrane, and module Figure 18 shows the results of comparing the performance of CD-1-Cell, CD-4-Module and other separation membranes. Figure 19 shows the general characteristics of the other separation membranes in Figure 18.

[0181] Figure 18 (a) shows the CO2 permeability and CO2 / CH4SF (or selectivity) obtained at 1000mL / min and 4000mL / min feed flow rates for CD-1-Cell and CD-4-Module at 50°C under dry conditions (open squares), ~3kPa wet conditions (half-filled squares), and ~12kPa wet conditions (full black squares). (b) shows the CO2 permeability versus CO2 / CH4SF (or selectivity) measured at 50°C-60°C under dry conditions (open squares), ~3kPa wet conditions (half-filled squares), and ~12kPa wet conditions (full black squares). In particular, (a) and (b) further include the separation performance of CD membranes at dry conditions at 30 °C. In (a), the upper limits of Robeson and thermally rearranged (TR) polymers are shown by the solid and dashed black lines, respectively. In (a) and (b), the performance of metal-organic framework (MOF), carbon and mixed matrix membranes are included. The performance of polymeric membranes is added in (a) and the performance of other zeolite / zeotype membranes in (b). For (c) CD-1-Cell and (d) CD-4-Module, the CO2 capture rate and purity on the permeate side and the CH4 capture rate and purity on the retentate side were confirmed by feed flow rate at 30 °C, dry condition (open squares), 50 °C, ~3 kPa wet condition (half-filled squares), and ~12 kPa wet condition (full black squares). In the enlarged area, the capture rate and purity appeared to be greater than (c) 90% and (d) 80%, respectively. (e) CD-1-Cell and (f) CD-4-Module are shown as functions of CO2 permeability and CO2 / CH4SF as a function of feed flow rate at 30 °C, ~3 kPa wet condition (half-filled squares), and ~12 kPa wet condition (full black squares). Here, the recovery rate is indicated by the size of the symbol.

[0182] Figures 18(a) and (b) show that the separation performance of the tubular CD membrane heteroepitaxially grown at 30°C to 50°C under dry and wet conditions is superior or similar to other zeolite / zeotype membranes, and superior to polymer membranes, metal-organic framework, and carbon and mixed matrix membranes.

[0183] In Figure 18(a), the CO2 / CH4 separation performance of the CD membrane, regardless of the presence or absence of water vapor in the feed, exceeded the upper limits of Robeson and thermally rearranged (TR) polymers when compared with other polymeric membranes, metal-organic frameworks (MOFs), carbon, and mixed matrix membranes. In particular, the CD membrane has high CO2 permeability due to its molecular sieve-based cutoff and high CO2 permeability. In addition, the CD membrane has hydrophobic properties and showed very high separation performance for CO2 / CH4 feed containing water vapor.

[0184] In order to evaluate the separation performance of the CD membrane from the viewpoint of separation membrane properties, in Fig. 18(b), the CO2 / CH4 separation performance was compared with other zeolite / zeotype membranes at 50℃-60℃ under dry conditions (open squares), ~3kPa wet conditions (half-filled squares), and ~12kPa wet conditions (fully black squares). Detailed information on the MOF, carbon and mixed matrix, and zeolite / zeotype membranes used in Fig. 18(a) are shown in Fig. 19.

[0185] Zeolite / zeotype separation membranes showed higher separation performance than MOF, carbon and mixed matrix separation membranes. The CD separation membrane of the present invention showed excellent CO2 / CH4 separation performance under both dry and wet conditions. In particular, at 50°C, even with the feed (approximately 12 kPa water vapor), both CD-1-Cell and CD-4-Module showed much higher CO2 permeability and permeation selectivity than other zeolite / zeotype separation membranes (CD-1-Cell: CO2 permeability 2.9×10 -7 mol m-2 ·s -1 ·Pa -1 and CO2 / CH4SF274; CD-4-Module: CO2 transparency 3.4×10 -7 mol m -2 ·s -1 ·Pa -1 and CO2 / CH4SF189).

[0186] The CD separation membrane in this embodiment is a combination of a hydrophobic thin separation membrane (ca. 2 μm) and an asymmetric high flux tubular support, and has rapid CO2 permeation and high separation performance even at saturated water vapor pressure (ca. 12 kPa) at 50 °C. SSZ-13 (outside 1) TIFF0007678266000001.tif14156, CHA (△), and SAPO-34 (▽) separation membranes showed similar CO2 permeability to the CD separation membrane of this example under dry conditions, but it was confirmed that the permeability was significantly lower than that of the CD separation membrane under wet conditions (ca. 2-5 kPa). This means that the separation membrane made of hydrophobic DDR zeolite, which can maintain high separation performance regardless of the presence or absence of water vapor in the feed, shows excellent performance. In addition, under wet conditions (ca. 2-5 kPa), the CO2 permeation selectivity of the CD separation membrane (CO2 / CH4SF383 at 50 °C) was slightly lower than that of the ZSM-58@CHA hybrid separation membrane (denoted as SZ_O3 and SZ_O2) fabricated on an α-alumina disk support (CO2 / CH4SF398-446 at 50 °C), but the corresponding CO2 permeability was 5.9 × 10 -7 mol m -2 ·s -1 ·Pa -1 and appeared very high.

[0187] Since high separation performance in terms of CO2 permeability and permselectivity (which indicates separation membrane properties) is most important in practical applications, CD separation membranes fabricated on tubular supports are the most efficient for treating biogas. Experimental recovery rates and purities for CO2 on the permeate side and CH4 on the retentate side for the CD separation membrane substrates, CD-1-Cell and CD-4-Module, are plotted (Figure 1). 18 (c) and (d) of Fig. 17). The separation performance in terms of module characteristics, which are closely related to the actual separation process, was compared with that in terms of separation membrane characteristics. As previously verified, the inherent separation performance of the CD membrane in terms of permeability and permselectivity could be obtained at the maximum feed flow rate (Fig. 17 (a1) and (b1)). On the other hand, such separation performance was reflected in high CO2 purity (due to high CO2 permselectivity) and low CO2 recovery (due to CO2 molar flux during short residence time of the feed), which showed high CH4 recovery and low CH4 purity on the retentate side. At this time, since the number of CO2 molecules recovered is small, various separation steps must be performed.

[0188] As the feed flow rate decreases, the CO2 capture rate increases gradually (Figure 18 (c) and (d) to the right) high CO2 purity is maintained. Therefore, while the CO2 capture rate remains high, CH4 increases as the feed flow rate decreases (Figure 18 (c) and (d) are in the upper direction. 18With reference to the enlarged drawings inserted in (c) and (d) of Fig. 1, it can be seen that the recovery rate and purity of CO2 and CH4 are 90% or more in the case of CD-1-Cell and higher than 80% in the case of CD-4-Module. In the case of CD-1-Cell, at a low feed flow rate in the range of 25-50 mL / min, the recovery rate and purity of CO2 and CH4 are 90% or more at a water vapor pressure of ca. 3 kPa at 50 °C under wet conditions. In addition, when the feed flow rate is further reduced to 25 mL / min, the recovery rate and purity of CO2 and CH4 are 95% or more up to a water vapor pressure of ca. 3 kPa and 90% or more at a saturated vapor pressure (ca. 12 kPa). In addition, the CD-4-Module, which is capable of a higher feed flow rate than the CD-1-Cell, can achieve a recovery rate and purity of CO2 and CH4 of 80% or more at a feed flow rate of 100-400 mL / min. In particular, at a supply flow rate of 100 mL / min, the recovery rate and purity of CO2 and CH4 were over 90% under dry and wet conditions (50°C and approximately 3 kPa), and 85% at 50°C and saturated water vapor pressure (approximately 12 kPa).

[0189] In terms of CO2 capture rate (module characteristics), the separation performance was compared between the CD-1-Cell and the CD-4-Module in terms of CO2 permeability and permeation selectivity (separation membrane characteristics). The CO2 purity, which is closely related to the permeation selectivity, was over 90% over the entire range of feed flow rates (Figure 1). 18 (c), (d)),Fig. 18 In (e) and (f) only the CO2 capture rate, which is sensitive to the feed flow rate, was considered. While the highest separation performance was shown in terms of CO2 permeability and permselectivity at the maximum feed flow rate, it was confirmed that the CO2 capture rate was low under dry conditions (open squares, 24-27%), ~3 kPa wet conditions (half-filled squares, 14%), and ~12 kPa wet conditions (fully filled squares, 6-7%). In other words, it was confirmed that effective separation requires high permselectivity along with optimal operation at the module level.

[0190] As the amount of steam in the feed increases, the separation performance gradually decreases in terms of CO2 permeability and permeability selectivity at relatively high feed flow rates (i.e., toward the lower left end), and under wet conditions at 50°C (saturated steam at about 12kPa), adequate CO2 permeability and permeability selectivity were observed at the lowest feed flow rates, while the CO2 recovery rate and purity were high in CD-1-Cell (97% and 91%) and CD-4-Module (95% and 87%). This means that it is very important to properly evaluate the performance of the separation membrane in terms of module characteristics.

[0191] The CO2 / N2 separation performance of the CD separation membrane was confirmed. The separation performance was 18.0±0.5 and 26.7±1.7 under dry and wet conditions at 30°C. Meanwhile, the CO2 / N2 separation performance was lower than that of CO2 / CH4, which is considered to be due to the small difference in molecular size (CH4 0.38nm vs. N2 0.364nm) having a large effect on the permeability. In particular, the CH4 adsorption amount was higher than N2 for DDR zeolite (i.e., higher driving force for permeation), and the final CH4 molar flux was very low. This is because the pores of DDR zeolite can function as a molecular sieve more effectively by permeating CH4. Nevertheless, the CO2 / N2 separation ability of the CD separation membrane according to this embodiment was much higher than that of other zeolite separation membranes.

[0192] As described above, in this example, a thin hybrid zeolite membrane with a thickness of 2 μm was fabricated as a CD separation membrane by secondary growth of DDR zeolite using 1-adamantylamine on a CHA zeolite seed layer. The fabricated CD separation membrane was subjected to air heat treatment and ozone heat treatment, respectively. In particular, the ozone heat treatment was performed at a low temperature, and it was confirmed that no defect structure was generated in the DDR phase (0.36 × 0.44 nm2) of the CD separation membrane fabricated. Therefore, the ozone heat-treated CD separation membrane showed particularly high performance in gas separation. The CD separation membrane showed very high CO2 permeation selectivity (maximum CO2 / CH4SF498±93 at 30°C) and molecular sieve performance (motion diameters of CO2 and CH4 were 0.33 and 0.38 nm, respectively).

[0193] The DDR@CHA hybrid membrane was fabricated on a high-flux asymmetric α-Al2O3 support and showed high flux CO2 permselectivity (CO2 permeability (1.2±0.1)×10 at 30 °C). -6 mol m -2 ·s -1 ·Pa -1 In particular, the highly hydrophobic nature of the hybrid membrane made of continuous silicon-based DDR zeolite resulted in a high flux of CO2 permeation selectivity (CO2 permeability of (5.9 ± 0.7) × 10) even in the presence of water vapor at 50 °C (corresponding to a biogas stream). -7 mol m -2 ·s -1 ·Pa -1 and CO2 / CH4SF3 83±82).

[0194] In addition to confirming the separation performance in terms of permeability and SF from the perspective of the separation membrane, we confirmed the recovery rate and purity of CO2 and CH4 under both dry and wet conditions, which are closely related to biogas upgrading. We also compared and confirmed the separation performance from the perspective of the attributes of the separation membrane and module (or process). As a result, we found that high CO2 permeability selectivity is necessary to achieve high CO2 purity, while CO2 permeability is determined by the characteristics of the feed in the bulk as well as diffusion through the separation membrane, and is intricately related to the CO2 recovery rate. In other words, we were able to confirm that the recovery rate and purity of CO2 molecules that permeate quickly on the permeate side are closely related to the recovery rate and purity of CH4 molecules on the retentate side, and have a significant impact on the separation performance of the separation membrane, especially from the perspective of the module (or process).

[0195] 7. Evaluation of liquid separation performance of CD membrane FIG. 20 shows the results of evaluating the liquid separation performance using the ozone heat-treated CD separation membrane.

[0196] In Figure 20, the HO / 1,2-hexanediol separation performance was evaluated using the ozone heat-treated CD separation membrane, and the separation performance at temperatures of 30°C and 60°C and the separation performance at 60°C over time were confirmed. The HO / 1,2-hexanediol mixture was composed of 75wt% water and 25wt% 1,2-hexanediol by weight.

[0197] At 30°C, it is 0.85kg m -2 h -1 and a separation factor of 1600. At 60°C, it has a water permeability of 3.33 kg m -2 h -1It was confirmed that dehydration was performed with high purity, with a water permeability of 1.0 and a high separation factor of 1800. In particular, in a long-term stability test at 60℃, the catalyst maintained a stable and high 1,2-hexanediol dehydration performance for 240 hours.

[0198] In other words, the CD membrane of this example was confirmed to be capable of separating water with high purity in addition to separating gas mixtures, and could be used for a long period of time even at a high temperature of 60°C.

[0199] It should be understood by those skilled in the art to which the present invention pertains that the present invention may be embodied in other specific forms without changing the technical spirit or essential features of the present invention. Therefore, the above-described embodiments should be understood to be illustrative in all respects and not limiting. The scope of the present invention is defined by the claims rather than the above detailed description, and all modifications or alterations derived from the meaning and scope of the claims and their equivalent concepts should be interpreted as being included in the scope of the present invention.

Claims

1. A CHA-DDR series zeolite separation membrane comprising a CHA structure and a DDR structure, A first layer including a CHA structure and a DDR structure; and a second layer disposed on the first layer and including a DDR structure; Including, The CHA-DDR series zeolite separation membrane is in the form of a film having a thickness of 100 nm to 4 um; The first layer has an average thickness of 50 nm to 2 um; The average thickness of the second layer is 10 nm to 2 um; CHA-DDR series zeolite separation membrane.

2. 2. The CHA-DDR series zeolite separation membrane according to claim 1, wherein a surface portion of the second layer opposite to the first layer has a shape having continuous pyramidal protrusions, and a (101) peak appears when measured by XRD using CuKα radiation.

3. The CHA structure of the first layer is manufactured from a CHA precursor solution; The CHA precursor solution comprises a first organic structure derivative, SiO 2 , and H 2 O; the first organic structure derivative, the SiO 2 , the H 2 O, the sodium compound, and the aluminum compound are in a molar ratio of 0.1 to 1000:100:100 to 50000:0 to 500:0 to 100, The first organic structure derivative may include TMadaOH (N,N,N-trimethyl adamantylammonium hydroxide) and TMadaBr (N,N,N-trimethyl adamantylammonium hydroxide). bromide), TMAdaF (N,N,N-trimethyl adamantylammonium fluoride), TMAdaCl (N,N,N-trimethyl adamantylammonium chloride), TMAdaI (N,N,N-trimethyl adamantylammonium iodide), TEAOH (tetraethylammonium hydroxide), TEABr (tetraethylammonium bromide), TEAF (tetraethylammonium fluoride), TEACl (tetraethylammonium chloride), TEAI (tetraethylammonium iodide), dipropylamine, and cyclohexylamine. The CHA-DDR series zeolite separation membrane according to claim 1,

4. The DDR structure of the first layer or the second layer is manufactured from a DDR precursor solution; The DDR precursor solution includes SiO 2 , a second organic structure derivative, and H 2 O; the SiO 2 , the second organic structure derivative, the H 2 O, the sodium compound, and the aluminum compound are each present in a molar ratio of 100:1 to 1000:10 to 100000:0 to 500:0 to 100; The second organic structure derivative is methyltropinium iodide, methyltropinium bromide, methyltropinium fluoride, methyltropinium chloride, methyltropinium hydroxide, quinuclidinium, TEAOH (tetraethylammonium hydroxide), TEABr (tetraethylammonium bromide), TEAF (tetraethylammonium 2. The CHA-DDR series zeolite separation membrane according to claim 1, wherein the zeolite is at least one selected from the group consisting of tetraethylammonium chloride (TEACl), tetraethylammonium iodide (TEAI), ethylenediamine, and adamantylamine.

5. The CHA-DDR series zeolite separation membrane according to claim 1, having a carbon dioxide permeability of 1×10 −9 mol·m −2 ·s −1 ·Pa −1 to 1×10 −5 mol·m −2 ·s −1 ·Pa −1 .

6. The CHA-DDR series zeolite separation membrane as described in claim 1, wherein the CHA structure is contained in an amount of 25 to 95 parts by weight per 100 parts by weight in the overall crystal structure of the CHA structure and DDR structure of the first layer and the second layer.

7. When carbon dioxide and methane are mixed in a molar ratio of 50:50, The recovery rate of the carbon dioxide is 10% to 100% and the purity is 50% to 100%; The CHA-DDR series zeolite separation membrane according to claim 1, wherein the methane recovery rate is 50% to 100% and the methane purity is 30% to 100%.

8. When carbon dioxide and nitrogen are mixed gases in a molar ratio of 15:85, The recovery rate of the carbon dioxide is 10% to 100% and the purity is 20% to 100%; 2. The CHA-DDR series zeolite separation membrane according to claim 1, wherein the nitrogen recovery rate is 30% to 100% and the purity is 30% to 100%.

9. The CHA-DDR series zeolite separation membrane of claim 1, for separating gas and gas mixtures, gas and liquid mixtures, or liquid and liquid mixtures.

10. A primary growth step of forming seed particles containing a hydrothermally produced CHA structure using a CHA precursor solution containing a first organic structure derivative; and a secondary growth step of forming a layered structure including a DDR structure so as to cover the seed particle by a hydrothermal synthesis method using a DDR precursor solution including a second organic structure derivative, the DDR precursor solution including SiO 2 , a second organic structure derivative, and H 2 O, and the second organic structure derivative including adamantylamine; Including, A method for producing a CHA-DDR series zeolite separation membrane having a film shape with a thickness of 100 nm to 5 um and including a CHA structure and a DDR structure.

11. The primary growth step comprises: Using the CHA precursor solution, synthesize seed particles containing a CHA structure by a hydrothermal synthesis method; Dispersing the seed particles in a solvent to form a suspension; immersing a support in the suspension to coat the seed particles on the surface of the support; drying the seed particle coated support; After the drying is completed, the seed particle-coated support is heat-treated at 300° C. to 550° C. for 1 hour to 24 hours; The secondary growth step includes: The method for producing a CHA-DDR series zeolite separation membrane according to claim 10, comprising adding a DDR precursor solution and a support on which the seed particles are coated, and carrying out hydrothermal synthesis.

12. In the primary growth step, The seed particles are provided in the form of a plurality of particles on a support; The method for producing a CHA-DDR series zeolite separation membrane according to claim 10, wherein the support includes at least one of α-alumina, γ-alumina, polypropylene, polyethylene, polytetrafluoroethylene, polysulfone, polyimide, silica, glass, mullite, zirconia, titania, yttria, ceria, vanadia, silicon, stainless steel, carbon, calcium oxide, and phosphorus oxide.

13. The method for producing a CHA-DDR series zeolite separation membrane as described in claim 12, wherein the support is provided in a tubular shape having a high permeability of 1×10 −6 mol·m −2 ·s −1 ·Pa −1 to 1×10 −4 mol·m −2 ·s −1 ·Pa −1 .

14. The method for producing a CHA-DDR series zeolite separation membrane as described in claim 10, wherein the seed particles are formed in a plurality of pieces, and the average length of the seed particles is 10 nm to 1 μm.

15. In the primary growth step, The CHA precursor solution comprises a first organic structure derivative, SiO 2 , and H 2 O; the first organic structure derivative, the SiO 2 , the H 2 O, the sodium compound, and the aluminum compound are in a molar ratio of 0.1 to 1000:100:100 to 50000:0 to 500:0 to 100, The first organic structural derivative may be TMadaOH (N,N,N-trimethyl adamantylammonium hydroxide) or TMadaBr (N,N,N-trimethyl adamantylammonium hydroxide). bromide), TMadaF (N,N,N-trimethyl adamantylammonium fluoride), TMadaCl (N,N,N-trimethyl adamantylammonium chloride), TMAdaI (N,N,N-trimethyl adamantylammonium iodide), TEAOH (tetraethylammonium hydroxide), TEABr (tetraethylammonium bromide), TEAF (tetraethylammonium fluoride), TEACl (tetraethylammonium chloride), TEAI (tetraethylammonium iodide), dipropylamine, and cyclohexylamine, any one or more of; The method for producing a CHA-DDR series zeolite separation membrane according to claim 10, wherein the hydrothermal synthesis is carried out for 6 hours to 400 hours at a temperature range of 100°C to 250°C.

16. In the secondary growth step, the molar ratios of the SiO 2 , the second organic structure derivative, the H 2 O, the sodium compound, and the aluminum compound in the DDR precursor solution are 100:1 to 1000:10 to 100000:0 to 500:0 to 100; The method for producing a CHA-DDR series zeolite separation membrane according to claim 10, wherein the hydrothermal synthesis is carried out for 6 hours to 400 hours at a temperature of 100°C to 250°C.

17. The CHA precursor solution and the DDR precursor solution each contain Si, and at least one of the CHA precursor solution and the DDR precursor solution contains Al, and The CHA structure has a molar ratio of Si:Al of 100:0-10; The method for producing a CHA-DDR series zeolite separation membrane according to claim 10, wherein the DDR structure has a molar ratio of Si:Al of 100:0 to 10:

10.

18. The method further comprises a heat treatment step after the secondary growth step, The method for producing a CHA-DDR series zeolite separation membrane according to claim 10, wherein the heat treatment step is carried out in an ozone atmosphere at a temperature range of 100° C. to 300° C.

19. The method for producing a CHA-DDR series zeolite separation membrane according to claim 18, wherein the CHA-DDR series zeolite separation membrane contains 1 wt % or less of adamantylamine inside the pores.

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