Gas separation unit, gas separation apparatus, and gas separation method

Abstract

It is known that increasing the pressure and lowering the temperature increases the amount of gas adsorbed by a gas separation agent. However, when CO2 gas, for example, is adsorbed by a gas separation agent, thermal energy is generated by the adsorption. As a result, heat accumulates in the gas separation unit due to the heat generated during adsorption, causing the temperature to rise, and consequently, the amount of gas adsorbed may decrease. Therefore, the present invention aims to provide a gas separation unit, a gas separation apparatus, and a gas separation method that can suppress the accumulation of heat. [Solution] A gas separation unit is provided, comprising a gas separator and an outer cylinder, wherein the gas separator includes a substrate having a thermal conductivity of 45 W / m·K or more, and a gas separation agent supported on the substrate, and the gas separator is housed in the outer cylinder such that it forms a gas flow path.

Description

[Technical Field]

[0001] The present invention relates to a gas separation unit, a gas separation apparatus, and a gas separation method. [Background technology]

[0002] Pressure swing adsorption (PSA) systems, which use gas separation agents, are widely used as a method for separating industrially important gases such as oxygen and nitrogen. For example, when separating two gases from a mixture, a gas separation agent with different adsorption capacities for the two gases is packed into an adsorption column. When the mixed gas is introduced, one of the gases is selectively adsorbed by the gas separation agent. As a result, a large amount of unadsorbed gas remains in the gas phase, and this is recovered by reducing the pressure. Porous gas separation agents such as zeolites and activated carbon are widely used for this purpose, and oxygen-generating PSA, nitrogen-generating PSA, and others are widely adopted. Separation methods using gas separation agents are expected to be energy-efficient. Furthermore, in addition to PSA, there is also temperature swing adsorption (TSA) systems, which vary the temperature of the gas separation agent. This method is based on the principle that, similar to PSA, gas separation agents with different adsorption capacities are packed into an adsorption tower, a mixed gas is introduced while the gas separation agent is at a low temperature to selectively adsorb one of the gases onto the gas separation agent, the unadsorbed gas components remaining in the gas phase are removed, and then the temperature is raised to desorb and recover the adsorbed components.

[0003] For example, as a separation method using a gas separation agent, Patent Document 1 discloses a pressure fluctuation adsorption gas separation method using a plurality of adsorption towers filled with an adsorbent that has a relatively high adsorption capacity for carbon dioxide and a relatively low adsorption capacity for hydrogen, which separates blast furnace gas containing carbon dioxide, nitrogen, hydrogen, and carbon monoxide from blast furnace gas. The method involves repeatedly performing a cycle that includes an adsorption step in which the blast furnace gas is introduced into the adsorption tower when the inside of the adsorption tower is under relatively high pressure, and the carbon dioxide in the blast furnace gas is adsorbed onto the adsorbent, and the unadsorbed gas is discharged from the adsorption tower; and a desorption step in which carbon dioxide is desorbed from the adsorbent when the inside of the adsorption tower is under relatively low pressure, and the desorbed gas is discharged outside the tower. The method is characterized in that the unadsorbed gas from the adsorption tower is recovered via a hydrogen recovery pipe from the start of the adsorption step to an intermediate point, and then discharged via an outlet pipe different from the hydrogen recovery pipe. Furthermore, Patent Document 2 discloses a temperature swing adsorption method for removing contaminants from a gas stream using an adsorbent, which involves bringing the adsorbent and the gas stream into contact at an initial temperature to adsorb the contaminants, and then raising the temperature of the adsorbent to desorb the contaminants. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2009-226258 [Patent Document 2] Japanese Patent Publication No. 2005-254235 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] Generally, it is known that to increase the adsorption amount of a gas adsorbed by a gas separation agent, the pressure should be increased and the temperature should be decreased. However, for example, when CO2 gas is adsorbed by a gas separation agent, heat energy is generated by the adsorption. Therefore, due to the heat during adsorption, heat accumulates in the gas separation unit and the temperature rises. As a result, the adsorption amount of the gas may decrease. In addition, due to its nature, the gas separation agent has a high porosity and a large surface area, and this structure results in a low thermal conductivity. As a result, it is difficult to dissipate the heat accumulated in the gas separation unit, and it is difficult to suppress the accumulation of heat.

[0006] Therefore, an object of the present invention is to provide a gas separation unit, a gas separation device, and a gas separation method capable of suppressing heat accumulation.

Means for Solving the Problems

[0007] In order to achieve the above object, the inventors of the present invention focused on a gas separation unit, particularly a gas separation body on which a gas separation agent is supported, and conducted studies. As a result, by using a gas separation unit having a specific gas separation body, it was found that the thermal energy (for example, adsorption heat) generated inside the gas separation unit can be efficiently transferred to the surface, that is, the accumulation of heat inside the gas separation unit can be suppressed, and the present invention was completed.

[0008] The present invention that has achieved the above object is as follows. (1) A gas separation unit having a gas separation body and an outer cylinder, where the gas separation body includes a base material having a thermal conductivity of 45 W / m·K or more and a gas separation agent supported on the base material, and the gas separation body is housed in the outer cylinder so as to form a gas flow path gas separation unit. (2) The gas separation unit according to (1), wherein the base material includes at least one selected from copper, aluminum, iron, and galvanized steel sheets. (3) The gas separation unit according to (1) or (2), wherein the gas separation body has a honeycomb shape. (4) The gas separation unit according to any one of (1) to (3), wherein the gas separator has at least one shape selected from wire-like and tape-like. (5) The gas separation unit according to any one of (1) to (4), wherein the gas separation agent comprises a porous coordination polymer, a zeolite, or a combination thereof. (6) The gas separation unit according to any one of items (1) to (5), wherein the gas separation agent adsorbs 20 mL or more of CO2 gas per gram of gas separation agent at 0°C and 1 atmosphere. (7) The gas separation unit according to any one of (1) to (6), wherein the gas separation agent comprises a gate-type porous coordination polymer. (8) A gas separation unit according to any one of items (1) to (7), wherein the gas separation agent adsorbs CO2 gas at 0°C and less than 1 atmosphere. (9) The gas separation unit according to any one of (1) to (8), wherein the gas separator does not have a binder. A gas separation apparatus comprising a gas separation unit as described in any one of items (10)(1) to (9). A gas separation method comprising passing two or more mixed gases through a gas separation unit described in any one of items (1) to (9) above, and adsorbing and separating a specific gas from the mixed gas. A gas separation method comprising passing two or more mixed gases through a gas separation unit described in any one of items (1) to (9), and manipulating at least one of the pressure and temperature to adsorb and separate a specific gas from the mixed gas. A gas separation method comprising passing two or more mixed gases through a gas separation unit described in any one of items (1) to (9), and manipulating the temperature to adsorb and separate a specific gas from the mixed gas. [Effects of the Invention]

[0009] According to the gas separation unit, gas separation apparatus, and gas separation method of the present invention, heat accumulation can be suppressed. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is a schematic diagram illustrating the gas separator in the gas separation unit of the present invention (Figure 1(A): Top view of the gas separator, Figure 1(B): Perspective view of the gas separator). [Figure 2] Figure 2 is a schematic diagram illustrating the gas separator in the gas separation unit of the present invention (Figure 2(A): Top view of the gas separator, Figure 2(B): Perspective view of the gas separator). [Figure 3] Figure 3 is a schematic diagram illustrating the gas separation unit of the present invention (Figure 3(A): base material, Figure 3(B): gas separator, Figure 3(C): gas separation unit). [Figure 4] Figure 4 is a schematic diagram illustrating the gas separation unit of the present invention (Figure 4(A): base material, Figure 4(B): gas separator, Figure 4(C): gas separation unit). [Figure 5] Figure 5 is a graph illustrating gate-type porous coordination polymers. [Figure 6] Figure 6 shows the HKUST-1 in the example (Figure 6(A): X-ray diffraction (XRD) pattern, Figure 6(B): adsorption isotherm, Figure 6(C): scanning electron microscope (SEM) image). [Figure 7] Figure 7 shows the Mg-MOF-74 in the example (Figure 7(A): XRD pattern, Figure 7(B): adsorption isotherm, Figure 7(C): ​​SEM image). [Figure 8] Figure 8 shows the type A monolith used as the substrate in Example 1 (Figure 8(A): top view of the substrate, Figure 8(B): perspective view of the substrate). [Figure 9] Figure 9 shows the setup of the apparatus for evaluating breakthrough characteristics in the embodiment (Figure 9(A): overall view, Figure 9(B): near the gas separation unit). [Figure 10] Figure 10 is a graph showing the breakthrough characteristics in Example 1. [Figure 11] Figure 11 is a graph showing the breakthrough characteristics in Comparative Example 1. [Figure 12] Figure 12 is a graph showing the breakthrough characteristics in Example 2. [Figure 13]Figure 13 shows the gas separator in Example 3 (Figure 13(A): External view of the gas separator, Figure 13(B): SEM image of the gas separator). [Figure 14] Figure 14 is a graph showing the breakthrough characteristics in Example 3. [Figure 15] Figure 15 shows a schematic scheme of pressure swing adsorption (PSA) in Example 4. [Figure 16] Figure 16 is a graph showing the PSA results in Example 4. [Figure 17] Figure 17 shows a schematic scheme of pressure-temperature swing adsorption (PTSA) in Example 5. [Figure 18] Figure 18 is a graph showing the results of PTSA in Example 5. [Figure 19] Figure 19 shows the type B monolith used as the substrate in Example 6. [Figure 20] Figure 20 shows the adsorption isotherm of gas separation unit D in Example 6. [Figure 21] Figure 21 shows the simulation results of pressure loss in Example 6. [Modes for carrying out the invention]

[0011] The embodiments of the present invention will be described in detail below. However, the present invention is not limited to the embodiments described below, and can be implemented with various modifications within the scope of the gist of the invention. Furthermore, in the description of the drawings, the same elements are denoted by the same reference numerals, and redundant explanations are omitted.

[0012] Gas separation unit The gas separation unit of the present invention is It has a gas separator and an outer cylinder, The above gas separator comprises a substrate having a thermal conductivity of 45 W / m·K or more, and a gas separation agent supported on the above substrate. The gas separator is housed in the outer cylinder in such a manner that it forms a gas flow path.

[0013] According to the gas separation unit of the present invention, heat accumulation can be suppressed.

[0014] For example, structures are known that have a ceramic or paper matrix (drying wheel) with low thermal conductivity as a base material, and an adsorbent supported on the base material (for example, a honeycomb-shaped structure). These structures are used in slow adsorption processes that do not require high-speed heat exchange (for example, dehumidification). On the other hand, in cases where a large amount of thermal energy is rapidly exchanged, such as in adsorption heat pumps and thermal storage, adsorbents such as gas separation agents are sometimes directly supported on plate heat exchangers. However, when adsorbents are supported on plate heat exchangers, for example, the structure on which the adsorbent is supported becomes bulky and large, making it difficult to manufacture in shapes other than the common ones. Therefore, it is expected that a compact and high-performance thermal management system can be provided by supporting a gas separation agent on a base material with high thermal conductivity, specifically a base material with a thermal conductivity of 45 W / m·K or higher.

[0015] Although not limited to theory, because the gas separation agent is supported on a substrate with a relatively high thermal conductivity, specifically a substrate with a thermal conductivity of 45 W / m·K or higher, even if heat is generated due to gas adsorption onto the gas separation agent (adsorption heat), the thermal energy can be efficiently transferred from the inside of the gas separation unit to the surface, thereby suppressing the accumulation of heat in the gas separation unit.

[0016] <Shape of the gas separator> In the gas separation unit according to an embodiment of the present invention, the gas separator is housed in an outer cylinder so as to form a gas flow path. Therefore, a mixed gas can flow through the gas separation unit, and a specific gas in the mixed gas (for example, CO2 in exhaust gas) can be adsorbed and separated by a gas separation agent supported on a substrate.

[0017] The shape of the gas separator may be a honeycomb shape. Specifically, the shape of the gas separator may be, for example, a honeycomb monolith structure as described later, or a honeycomb shape formed by overlapping and winding corrugated and flat plates.

[0018] Figures 1 and 2 are schematic diagrams showing one embodiment of the gas separator of the gas separation unit in the present invention, but are not limited to this embodiment.

[0019] The gas separator 110 shown in Figure 1 has a honeycomb-shaped monolithic structure. Here, a monolithic structure is a one-piece porous structure in which a fine mesh-like framework is continuous in three dimensions. The gas separator 110 shown in Figure 1 has multiple pores, and a gas separation agent is supported on the surface of the partitions that form the multiple pores. Because the gas separator 110 shown in Figure 1 has relatively large pores, specifically having a porosity (the ratio of space to the volume of the gas separator 110) of 30-90%, it can support a large amount of gas separation agent and allow a large flow rate of gas to pass through it. The gas separator 110 shown in Figure 1 may also be manufactured by coating a slurry containing a gas separation agent, as described later, onto a substrate having a honeycomb-shaped monolithic structure and drying it. The substrate having a honeycomb-shaped monolithic structure may be manufactured, for example, by a 3D printer. The gas separator 110 shown in Figure 2 also has a honeycomb-shaped monolithic structure. The gas separator 110 shown in Figure 2 has relatively small pores, specifically having a porosity (the ratio of space to the volume of the gas separator 110) of 20-50%, and therefore the specific surface area of ​​the pores is large, specifically, for example, 0.001-0.1 m². 2 The pressure is low, and therefore the gas separation agent supported on the surface of the pore partitions can efficiently come into contact with the mixed gas. The gas separator shown in Figure 2 may also be manufactured by directly supporting the gas separation agent on a substrate having a honeycomb-shaped monolithic structure, as will be described later. When the gas separator has a honeycomb-shaped monolithic structure, the pressure loss can be controlled by controlling the pore diameter within the monolith, the thickness of the substrate, etc. Low pressure loss is particularly important when considering the separation of large quantities of gas.

[0020] When the gas separator has a honeycomb shape formed by overlapping and winding corrugated and flat plates, the corrugated and flat plates are not particularly limited, but they may or may not have openings, and it is preferable that they have openings from the viewpoint of reducing pressure loss.

[0021] The shape of the gas separator may be at least one shape selected from, for example, a wire shape or a tape shape.

[0022] Figures 3 and 4 are schematic diagrams showing one embodiment of the gas separation unit in the present invention, but are not limited to this embodiment.

[0023] Figure 3(A) shows a copper foil having a tape-like shape as a base material, and Figure 3(B) shows a gas separator in which a gas separation agent is directly supported on the tape-like copper foil. Thus, prioritizing thermal conductivity, the base material may be copper foil having a tape-like shape. As shown in Figure 3(C), the gas separation unit 100 is housed in an outer cylinder 120 such that the tape-like gas separator 110 forms a gas flow path. With this structure, excellent thermal conductivity and low pressure loss can be expected. Also, Figures 4(A) and (B) show wire-shaped copper fibers as a base material. The wire-shaped copper fibers may have a diameter of, for example, 0.2 mm or less. Thus, prioritizing thermal conductivity, the base material may be copper fibers having a wire-like shape. As shown in Figure 4(C), the gas separation unit 100 is housed in an outer cylinder 120 such that the tape-like gas separator 110 forms a gas flow path. The length of the tape-shaped or wire-shaped gas separator needs to be sufficient to support effective suppression of heat accumulation from the center of the outer cylinder to the outer diameter of the outer cylinder, and is preferably longer than the diameter of the outer cylinder. For more effective suppression of heat accumulation, the length of the tape-shaped or wire-shaped gas separator can be appropriately selected. The gas separation unit 100 shown in Figures 3(C) and 4(C) has a very high specific surface area, which is considered to enable efficient contact with the mixed gas. For example, when the gas separation agent is directly supported on the substrate as described later, a thin layer of the gas separation agent is formed on the substrate. Since heat diffusion in a thin layer is generally considered to be very fast, it is considered that heat accumulation can be further suppressed in such cases. The aspect ratio of the tape-shaped or wire-shaped gas separator may be, for example, 5 or more, 10 or more, 20 or more, 50 or more, or 100 or less, or 1000 or less. Here, the aspect ratio is the value obtained by dividing the long axis of the gas separator by the short axis, and takes a value of 1 or more.

[0024] When the porosity (the ratio of space to the volume of the gas separation unit) of a gas separation unit with a gas separator is large, the pressure loss of the mixed gas decreases, making it easier to circulate a relatively large flow rate of the mixed gas. However, the gas separation efficiency becomes relatively low. On the other hand, when the porosity of the gas separation unit is small, the pressure loss of the mixed gas increases, making it disadvantageous to circulate a large flow rate of the mixed gas. However, the gas separation efficiency becomes relatively high. The porosity of the gas separation unit should be appropriately selected considering the balance between the flow rate of the mixed gas and the gas separation efficiency, and the porosity of the gas separation unit can be 10 to 90 volume percent. For example, when circulating a large flow rate of mixed gas, it is preferable to set the porosity to 40 to 80 volume percent, taking into account the gas separation efficiency.

[0025] The outer cylinder is not particularly limited, but may be circular, elliptical, or polygonal. The length of the outer cylinder may be 10 mm or more, 30 mm or more, or 50 mm or more, or 5000 mm or less, 2000 mm or less, 1000 mm or less, 500 mm or less, or 200 mm or less. The equivalent outer diameter of the outer cylinder may be 5 mm or more, or 10 mm or more, or 5000 mm or less, 2000 mm or less, 1000 mm or less, 500 mm or less, 100 mm or less, or 50 mm or less. Here, the equivalent outer diameter refers to the outer diameter of a perfect circle having an outer circumference equal to its outer circumference.

[0026] <Composition of the gas separator> In a gas separation unit according to an embodiment of the present invention, the gas separator comprises a substrate having a thermal conductivity of 45 W / m·K or more, and a gas separator supported on the substrate. The gas separator may optionally include a binder or the like.

[0027] [Base material] The substrate has a thermal conductivity of 45 W / m·K or higher. The higher the thermal conductivity of the substrate, the more effectively heat accumulation can be suppressed. Furthermore, by increasing the thermal conductivity, the temperature change of the substrate can be accelerated, which may result in faster gas adsorption and desorption. To obtain these effects, the thermal conductivity of the substrate may be 100 W / m·K or higher, 200 W / m·K or higher, or 350 W / m·K or higher. There is no particular upper limit to the thermal conductivity of the substrate, and it may be 500 W / m·K or 450 W / m·K. The thermal conductivity of the substrate is determined by processing the substrate to a predetermined size (Φ18 mm × thickness 1 mm) and measuring it at room temperature using an MTPS (Modified Transient Plane Source).

[0028] The base material is not particularly limited, but examples include metal, carbon fiber, and carbon fiber reinforced plastic. From the viewpoint of thermal conductivity and availability, metal is preferred. The metal is not particularly limited, but may include at least one selected from copper (thermal conductivity: 398 W / m·K), aluminum (thermal conductivity: 237 W / m·K), iron (thermal conductivity: 80 W / m·K), and galvanized steel sheet (thermal conductivity: 50 W / m·K). Alternatively, the base material may be plated or vapor-deposited with the above metal.

[0029] [Gas separation agent] The gas separation agent is not particularly limited as long as it can adsorb gas, and may include a porous material. Examples of the porous material include, but is not limited to, porous coordination polymers, zeolites, activated carbon, etc. From the viewpoint of improving separation efficiency, the gas separation agent preferably includes a porous coordination polymer, a zeolite, or a combination thereof, and more preferably includes a gate-type porous coordination polymer. For example, in order to improve the separation efficiency of temperature swing adsorption (TSA), it is considered important that the increase or decrease in the amount of adsorption with temperature changes in the pressure range used (Δ amount of adsorption / Δ temperature) is large.

[0030] (Porous coordination polymer) Porous coordination polymers can be complexes of metal ions and ligands bound to them, and depending on the type of metal and ligand, they can take on various structures such as linear two-coordinate structures, planar four-coordinate structures, six-coordinate octahedral structures, and eight-coordinate cubic structures. The constituent metals and ligands of the porous coordination polymer can be appropriately selected depending on the type of gas to be separated.

[0031] The metals included in the porous coordination polymer are not particularly limited, but may include, for example, first transition metals belonging to the fourth period of the periodic table, such as manganese, chromium, iron, cobalt, and copper, as well as zinc; second transition metals belonging to the fifth period, such as ruthenium, palladium, and rhodium, as well as cadmium; third transition metals belonging to the sixth period, such as lanthanide metals (lanthanum, cerium, opraceodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, holmium, erbium, thulium, ytterbium, lutetium, etc.), hafnium, tantalum, tungsten, osmium, iridium, platinum, and mercury; and fourth transition metals belonging to the seventh period, such as actinide metals (actinium, thorium, protactinium, uranium, neptinium, plutonium, etc.), meitnerium, and roentgenium. The metals contained in the porous coordination polymer may be one or more selected from these groups.

[0032] The ligands included in the porous coordination polymer may be one or more selected from the group consisting of, for example, benzene derivatives, naphthalene derivatives, pyrazine derivatives, imidazole derivatives, triazole derivatives, pyrazole derivatives, pyridine derivatives, biphenyl derivatives, terphenyl derivatives, quaterphenyl derivatives, pentaphenyl derivatives, camphorate derivatives, triphenylene derivatives, camphor acid derivatives, porphyrin derivatives, and metal cyano derivatives.

[0033] The porous coordination polymer is not particularly limited, but it may adsorb 20 mL or more of CO2 gas per gram of gas separation agent at -10°C and 1 atm. In other words, the amount of adsorption by the porous coordination polymer may be, for example, 20 mL or more, 30 mL or more, or 50 mL or more per gram of gas separation agent at 0°C and 1 atm, or it may be 300 mL or less or 200 mL or less. Furthermore, the above-mentioned adsorption amount of gas separation agent at -10°C may be achieved at a higher temperature of 0°C. Also, CO2 gas may be adsorbed at 20 mL or more per gram of gas separation agent in the gas separation unit under conditions of -10°C or 0°C and 1 atm. Depending on the specifications of the separation unit, the amount of CO2 gas per gram of gas separation agent in the separation unit may vary even when using the same type of gas separation agent, but it is preferable that the gas separation agent has a CO2 gas adsorption capacity of 20 mL or more per gram. The amount of adsorption by the gas separation agent is measured by the constant volume method. In this method, the amount of gas separation agent adsorbed is measured by detecting the pressure change inside a container of a fixed volume that contains the gas separation agent.

[0034] (Gate-type porous polymer) Gate-type porous polymers adsorb or desorb specific gases in a gate-like manner in response to at least one of pressure changes or temperature changes, and therefore, because the amount of adsorption changes rapidly in response to either temperature or pressure changes, they can be suitably used. Currently known gate-type porous polymers include ELMs (Elastic Layer-structured Metal organic frameworks), Kagome, MILs, CIDs, and others. Literature on these gate-type porous polymers is as follows: ELMs are described in the literature by Kamidai et al., Int. J. Mol. Sci. 2010, 11, 3803. Kagomes are described in the literature by Sato et al., SCIENCE (2014) 343, 167, and by Zaworotko et al., Chem. Commun., 2004, 2534. MILs are described in the literature by Ferey et al., Chem. Soc. Rev., 2009, 38, 1380. CID compounds are described in Inubushi et al., Chem. Commun., 2010, 46, 9229, and Nakagawa et al., Chem. Commun., 2010, 46, 4258. Other examples are described in Kitaura et al., Angew. Chem. Int. Ed. 2003, 42, 428. Among these, ELM compounds, Kagome compounds, MIL compounds, and CID compounds are preferred in terms of their clear gating effect.

[0035] Here, a gate-type porous polymer is a material that exhibits gate-type isotherms. Gate-type isotherms refer to adsorption and desorption isotherms that show inflection points as shown in Figure 5, mainly due to structural changes in the porous polymer complex. The isotherms of a gate-type porous polymer complex are defined as the adsorption start gate pressure, adsorption completion gate pressure, gate adsorption amount, desorption start gate pressure, desorption completion gate pressure, and gate desorption amount, as shown in Figure 5.

[0036] The adsorption start gate pressure is the pressure at which the proportional relationship between adsorption amount and pressure increases sharply in the initial stages of adsorption (the increase in adsorption amount increases sharply in relation to the increase in gas pressure). The adsorption completion gate pressure is the pressure at which the proportional relationship between adsorption amount and pressure decreases sharply after the adsorption start gate pressure in the adsorption process (the increase in desorption amount decreases sharply in relation to the increase in gas pressure). The gate adsorption amount is the amount of adsorption between the adsorption start gate pressure and the adsorption completion gate pressure. The desorption start gate pressure is the pressure at which the proportional relationship between adsorption amount and pressure increases sharply in the initial stages of desorption (the increase in desorption amount increases sharply in relation to the increase in gas pressure). The desorption completion gate pressure is the pressure at which the proportional relationship between adsorption amount and pressure decreases sharply after the desorption start gate pressure in the desorption process (the increase in desorption amount decreases sharply in relation to the increase in gas pressure). The gate desorption amount is the amount of desorption from the desorption start gate pressure to the desorption completion gate pressure. Both the adsorption-start gate pressure and the desorption-start gate pressure vary depending on the affinity between the adsorbent material and the gas being adsorbed; that is, they are lower when the affinity is high and higher when the affinity is low. Also, affinity increases at lower temperatures, so the gate pressure decreases. Therefore, because they fluctuate depending on the adsorbent material, gas type, and temperature, it is not possible to uniquely determine the pressure.

[0037] The gate-type porous polymer is not particularly limited, but for example, it may adsorb CO2 gas at 0°C and less than 1 atmosphere, and may be gate-adsorbed in particular.

[0038] The amount of gas separation agent to be loaded can be appropriately determined based on the required amount of gas to be separated, the amount of gas adsorbed by the separation agent, the temperature dependence of the adsorbed amount of the separation agent, etc. For example, it may be 1 to 8 mmol CO2 / g.

[0039] [Binder] The binder is not particularly limited, but a binder with high gas permeability is preferred. Specifically, examples include polyvinylpyrrolidone (PVP), nanocellulose (NC), microcellulose (NCC), cellulose nanofibril (CNB), etc., but the invention is not limited to these. Furthermore, from the viewpoint of firmly supporting the gas separation agent on the substrate, the binder content is preferably 0.5% to 20% by mass relative to the total amount of the gas separation agent and the binder.

[0040] The method for supporting the gas separation agent on the substrate is not particularly limited, and the gas separation agent may be supported by applying a slurry containing the gas separation agent by methods such as dip coating, spin coating, or powder coating, and then drying.

[0041] Alternatively, the gas separation agent may be directly supported on the substrate. A method for direct support is described, for example, in Tanihara et al., Bull. Chem. Soc. Jpn., 2016, 89, 1048. When the gas separation agent is directly supported on the substrate, the gas separator does not need to have a binder. Here, "gas separator without a binder" means that the binder content of the gas separator is less than 0.1% by mass relative to the total amount of gas separation agent and binder. By not using a binder, gas permeation is not hindered by the binder, resulting in improved adsorption efficiency. Furthermore, the absence of a binder relatively increases the amount of gas separation agent that can be supported, resulting in a higher effective amount of gas separation agent.

[0042] The gas separation unit according to an embodiment of the present invention can be applied to the separation of various gases. Examples of gas species include oxygen, nitrogen, argon, carbon dioxide, carbon monoxide, hydrogen, alkanes, alkenes, alkynes, and the like.

[0043] The gas separation unit according to the embodiment of the present invention is not particularly limited, but may be used alone or two or more gas separation units may be arranged in parallel or in series.

[0044] As described above, the gas separation unit according to the embodiment of the present invention can suppress the accumulation of heat in the gas separation unit. Therefore, the gas separation unit according to the embodiment of the present invention is suitably used in gas separation devices that adsorb and separate gases, such as pressure swing adsorption (PSA), temperature swing adsorption (TSA), and pressure-temperature swing adsorption (PTSA). These gas separation devices only need to include the gas separation unit according to the embodiment of the present invention in at least a part of it, and therefore the gas separation unit according to the embodiment of the present invention may be used alone or in combination with other gas separation units.

[0045] Gas separation method The gas separation method of the present invention involves passing a mixed gas of two or more types of gases through the gas separation unit described above, adsorbing a specific gas from the mixed gas, specifically adsorbing and separating at least one gas contained in the mixed gas. As for the gas separation method, the specific gas may be adsorbed and separated from the mixed gas by manipulating at least one of the pressure and temperature, or the specific gas may be adsorbed and separated from the mixed gas by manipulating at least the temperature.

[0046] One method of separation by manipulating temperature is TSA, which utilizes temperature changes. Specifically, TSA is a method in which a mixed gas at a predetermined temperature T1 is passed through a gas separation unit to adsorb the gas, and then the temperature is raised to a higher temperature T2 to desorb and recover the adsorbed gas. In the gas separation method of the present invention, because the thermal conductivity of the gas separation unit is high, this T1 / T2 cycle can be performed quickly, making it possible to increase the amount of gas processed per unit time.

[0047] One method of separation by manipulating pressure and temperature is PTSA, which utilizes both pressure and temperature changes. Specifically, PTSA is a method in which a mixed gas at a predetermined pressure P1 and temperature T1 is passed through a gas separation unit to adsorb the gas, and then the pressure is reduced to a lower pressure P2 and the temperature is raised to a higher temperature T2 to desorb and recover the adsorbed gas. In the gas separation method of the present invention, because the thermal conductivity of the gas separation unit is high, this T1 / T2 cycle can be performed quickly, making it possible to increase the amount of gas processed per unit time.

[0048] Another separation method involves manipulating temperature and humidity. Specifically, this method involves circulating a mixed gas at a predetermined humidity H1 and temperature T1 through a gas separation unit to adsorb the gas, then adjusting the humidity to H2 (higher than H1) and raising the temperature to T2 (higher than T1) to desorb and recover the adsorbed gas. In the gas separation method of the present invention, the high thermal conductivity of the gas separation unit allows for a rapid T1 / T2 cycle, increasing the gas processing rate per unit time.

[0049] The present invention will be described in more detail below with reference to examples, but the present invention is not limited in any way to these examples. [Examples]

[0050] In this example, the gas separation agent shown below was used. HKUST-1:[Cu3(BTC)2](BTC:1,3,5-benzenetricarboxylate). The X-ray diffraction (XRD) pattern, adsorption isotherm, and scanning electron microscope (SEM) image of HKUST-1 are shown in Figure 6. Mg-MOF-74:[Mg2(dobdc)](dobdc:2,5-dioxidiobenzene-1,4-dicarboxylate). The XRD pattern, adsorption isotherm (-10°C, 1 atm), and SEM image of Mg-MOF-74 are shown in Figure 7.

[0051] Example 1 Fabrication of Gas Separation Unit A A slurry containing HKUST-1 was prepared by mixing HKUST-1 (80 parts by mass) as a gas separation agent, polyvinylpyrrolidone (PVP) (20 parts by mass) as a binder, and an appropriate amount of ethanol as a dispersion medium, and performing ultrasonic treatment for 30 minutes. The prepared slurry containing HKUST-1 was injected into an aluminum type A monolith (length 50 mm, outer diameter 10 mm) (thermal conductivity 237 W / m·KW / m·K) having the shape shown in Figure 8, drying by circulating dry nitrogen gas, drying in an 80°C oven for 12 hours, and then vacuum treatment at 23°C for 24 hours to obtain a gas separator on which HKUST-1 was supported on the type A monolith. The obtained gas separator was housed in an outer cylinder to fabricate a gas separation unit A. The weights of HKUST-1 and PVP supported on the type A monolith were determined by measuring the weight of the type A monolith before and after supporting the HKUST-1. The weight of the HKUST-1 and PVP mounted on the Type A monolith was 0.254g.

[0052] Breakthrough characteristics of gas separation unit A Figure 9 shows a schematic diagram of the setup for evaluating breakthrough characteristics. The working gas (N2 and CO2) flowed from the intake port 6 to the exhaust port 7 of the gas separation unit 100. The temperature of the center of the gas separation unit 100 was measured using probes 9 and 11. Probes 9 and 11 were fixed at a depth of 5 mm from the intake port 6 and exhaust port 7, respectively. Probe 9, inserted from the intake port 6, measured the temperature of the center of the gas separation unit 100 on the intake port 6 side (T inlet-center The temperature (T) of the central part of the gas separation unit 100 on the exhaust port 7 side is measured by the probe 11 inserted from the exhaust port 7. outlet-center The temperature (T) of the surface of the gas separation unit 100 was measured. Meanwhile, the temperature of the surface of the gas separation unit 100 was measured by probes 10 and 12. The temperature (T) of the surface of the gas separation unit 100 on the intake port 6 side was measured by probe 10 near the intake port 6. inlet-surface The temperature (T) of the surface of the gas separation unit 100 on the exhaust port 7 side is measured by the probe 12 near the exhaust port 7. outlet-surface) was measured. Each probe was connected to a data logger via a lead wire 8. The evaluation of the breakthrough characteristics was carried out under the conditions of a temperature of -10°C, a CO2 partial pressure of 1 bar, and a gas flow rate of 0.1 L / min. The results of measuring the breakthrough characteristics of the gas separation unit A are shown in Fig. 10.

[0053] The temperature difference dT in Fig. 10 inlet-surface , dT outlet-surface , dT inlet-center , dT outlet-center is the temperature difference between the controlled environmental temperature (-10°C) and the temperature on the surface of the gas separation unit (T inlet-surface , T outlet-surface ), and the temperature inside the gas separation unit (T inlet-center , T outlet-center ). The purpose of this experiment is to show the temporal temperature profile and the rate at which heat moves from inside the system to the outside. At the beginning of the graph in Fig. 10, the temperatures of dT inlet-center and dT inlet-surface rose simultaneously. dT inlet-center and dT inlet-surface are the temperature changes on the intake port 6 side of the gas separation unit, because CO2 is adsorbed first. In Fig. 10, the temperature differences between the inside (dT inlet-center , dT outlet-center ) and the surface (dT inlet-surface , dT outlet-surface ) of the gas separation unit are small, indicating that the thermal connection is very good. The same is true for the sensor installed on the exhaust port 7 side.

[0054] 《Comparative Example 1》 《Fabrication of Gas Separation Unit a and Its Breakthrough Characteristics》 Instead of a type A monolith as the substrate, glass beads (thermal conductivity 0.083 W / m·K, diameter 1 mm) were used to obtain a gas separator in which HKUST-1 was supported on the glass beads. The obtained gas separator was housed in an outer cylinder to fabricate gas separation unit a. Here, the heat capacity of HKUST-1 was determined by the DSC method (DSC-60, Shimadzu Corporation) with Cp = 0.84 J / g·K. The value for the glass beads was extracted from the glass bead datasheet and was Cp = 0.84 J / g·K. The thermal conductivity of the glass beads and HKUST-1 was measured using a Trident Thermal Conductivity Instrument (C-Therm Technologies Ltd.), and was determined to be HKUST-1 = 0.075 W / m·K and GB = 0.083 W / m·K. The heat generation amount of CO2 adsorption was estimated by Clausius-Clapeyron equation analysis. The average value of the heat generation amount of CO2 adsorption was 25 J / mmol. The breakthrough characteristics of gas separation unit a were evaluated using the same method as in Example 1. The results of the measurement of the breakthrough characteristics of gas separation unit a are shown in Figure 11.

[0055] In the breakthrough characteristics of gas separation unit A in Example 1, the surface (dT) of gas separation unit A is inlet-surface dT outlet-surface The temperature of the gas separation unit A (dT) changes with CO2 adsorption. inlet-center dT outlet-center The temperature of the gas separation unit changed in accordance with the temperature of the gas separation agent (Figure 10). This indicates that the heat generated by the adsorption of CO2 onto the gas separation agent inside the gas separation unit is immediately transferred to the surface, i.e., heat accumulation inside the gas separation unit is suppressed. The breakthrough characteristics of gas separation unit A were confirmed to show a shorter adsorption time compared to gas separation unit a of Comparative Example 1 (Figures 10 and 11). Adsorption time is an important characteristic of the adsorption system and is one of the parameters that determine the efficiency of the cycle. In gas separation unit A, because the thermal conductivity of the substrate is high, heat accumulation is suppressed during the adsorption step, and as a result, the complete saturation time t of gas separation unit A is shortened. 1.0This was shortened. On the other hand, in the breakthrough characteristics of gas separation unit a shown in Figure 11, the internal temperature of gas separation unit a rises due to the heat generated by the adsorption of CO2 gas, but the internal temperature of gas separation unit a decreases until (dT inlet-center <0.5℃, dT outlet-center At temperatures below 0.5°C, the adsorption capacity of the gas separation agent cannot be fully exhibited, and as a result, the complete saturation time t 1.0 It is thought that it has grown larger. 0.9 For comparison, this shows the 90% saturation time for the adsorption amount.

[0056] Furthermore, the ability to suppress heat accumulation inside gas separation unit A suggests the possibility of even higher thermal management. inlet-center dT outlet-center ) and surface (dT inlet-surface dT outlet-surface Since the peak temperature values ​​of the gas separation unit showed only a slight difference, heat from inside the gas separation unit was quickly transferred to the surface. On the other hand, there is still room for improvement in heat dissipation from the surface of the gas separation unit. For example, it is expected that the thermal efficiency can be further increased by improving heat dissipation from the surface of the gas separation unit, specifically by using a heat transfer medium with high heat transfer capacity, such as water or a glycol mixture. This is considered to substantially demonstrate the great potential and benefits of the thermal management of the gas separation unit of the present invention.

[0057] Gas separation unit A and gas separation unit a have similar heat of adsorption based on the amount of adsorption. Although the heat capacity of gas separation unit a (5.47 J / K) is greater than that of gas separation unit A (3.56 J / K), the maximum temperature reached by gas separation unit a was higher than that of gas separation unit A. Immediately after the start of adsorption in gas separation unit a, the internal temperature (dT inlet-center dT outlet-center ) rises, but the surface temperature (dT inlet-surface dT outlet-surface The temperature stabilizes at approximately 0.5°C higher than the initial temperature, and this difference is the internal temperature ((dT inlet-center dT outlet-centerIt can be seen that it decreases slightly over time until it becomes low. This further demonstrates the advantages of the gas separation unit of the present invention. In a gas separation unit a such as Comparative Example 1, by increasing the heat capacity, dT inlet-surface dT outlet-surface As shown, even if it is possible to prevent extreme temperatures from being reached on the surface side of the gas separation unit, dT inlet-center dT outlet-center As shown, it is not possible to suppress the internal heat generation that interferes with the adsorption process.

[0058] Example 2 Fabrication of gas separation unit B and its breakthrough characteristics Gas separation unit B was prepared in the same manner as in Example 1, except that Mg-MOF-74 was used instead of HKUST-1 as the gas separation agent. The breakthrough characteristics of gas separation unit B were evaluated in the same manner as in Example 1. The results of the measurement of the breakthrough characteristics of gas separation unit B are shown in Figure 12.

[0059] As in Example 2, CO2 adsorption was also successful when other porous coordination polymers were used as gas separation agents. Similar to gas separation unit A using HKUST-1, gas separation unit B using Mg-MOF-74 also showed the smallest difference in temperature profile between the probe inserted inside the column and the probe on the outer surface of the column, demonstrating a small thermal gradient and high heat flux. dT on the intake port 6 side inlet-center and dT inlet-surface and dT on the exhaust port 7 side outlet-center and dT outlet-surface The differences were small and did not exceed 10% of the individual relative values ​​(Figure 12).

[0060] Example 3 Fabrication of gas separation unit C and its breakthrough characteristics A gas separator was obtained by directly supporting HKUST-1 on a tape-shaped copper foil (length 5-20 mm, width 1 mm, thickness 0.07 mm) (thermal conductivity 398 W / m·K) as a substrate. Direct support of HKUST-1 onto the substrate was carried out according to the method described in "Fabrication of Densely Packed HKUST-1 Metal Organic Framework Thin Layers on a Cu Substrate through a Controlled Dissolution of Cu" (Tanihara et al, Bull. Chem. Soc. Jpn., 2016, 89, 1048-1053). The obtained gas separator was housed in an outer cylinder to fabricate a gas separation unit C. Figure 13 shows the appearance and SEM image of HKUST-1 directly supported on the tape-shaped copper foil. The breakthrough characteristics of gas separation unit C were evaluated using the same method as in Example 1. The results of the measurement of the breakthrough characteristics of gas separation unit C are shown in Figure 14.

[0061] As shown in Example 3, the advantage of a gas separator in which the gas separation agent is directly supported on the substrate is the unparalleled thermal contact between the gas separation agent and the substrate, which is thought to enable bidirectional ultrafast heat exchange. Furthermore, since the gas separation agent is directly supported without using a binder, coating of the gas separation agent by the binder can be suppressed, and it is thought that the agent can be supported on the substrate without reducing the amount of adsorption. Gas separation unit C showed positive CO2 adsorption accompanied by a temperature rise due to the release of adsorption heat. The temperature rose immediately after the start of adsorption, and the temperature inside gas separation unit C (dT inlet-center dT outlet-center ) and surface (dT inlet-surface dT outlet-surfaceThe temperature difference between the two points was very small. This suggests that the thermal conductivity inside the system is good, and heat accumulation is more suppressed. Furthermore, Figure 14 shows that after the initial temperature rise, the system returned to its original temperature in a short time thanks to the improved thermal conductivity. In other words, in the adsorption step, the temperature rose due to the increase in heat of adsorption, and in the desorption step, the temperature decreased due to the supply of the necessary heat of desorption. For example, if the preheating and pre-aggregation steps of a PTSA system can be performed at a faster speed, improved thermal conductivity would be very beneficial for these systems.

[0062] Example 4 Pressure Swing Adsorption (PSA) Test of Gas Separation Unit A The pressure swing adsorption (PSA) test of gas separation unit A was performed by changing the partial pressure of CO2 in the N2 / CO2 mixed gas. Specifically, the pressure of the N2 / CO2 mixed gas in gas separation unit A was set to 1 bar, the partial pressure of CO2 was set to 1 bar during adsorption, and the partial pressure of CO2 was set to 0 bar during desorption. The flow rate of the N2 / CO2 mixed gas was set to 0.1 L / min at all stages, and the PSA test temperature was -10°C. Figure 15 shows a schematic scheme of the PSA cycle.

[0063] Figure 16 shows the breakthrough characteristics of the first and second PSA cycles of gas separation unit A. Regions S1 to S3 indicate the adsorption amount, with S1 = 4.41 mmol / g and S2 = 3.88 mmol / g. Since the amount of N2 adsorbed onto HKUST-1 is very small at the PSA test temperature of -10°C (N2 adsorption amount less than 0.5 mmol / g), it was confirmed that gas separation unit A can perform continuous CO2 adsorption by controlling the partial pressure using PSA without the need to completely evacuate the system.

[0064] Example 5 Pressure-temperature swing adsorption (PTSA) test of gas separation unit A. The pressure-temperature swing adsorption (PTSA) test of gas separation unit A was performed by varying the partial pressure of CO2 in the N2 / CO2 mixed gas and the temperature. Specifically, the pressure of the N2 / CO2 mixed gas in gas separation unit A was set to 1 bar, the CO2 partial pressure was set to 1 bar and the temperature to -10°C during adsorption, and the CO2 partial pressure was set to 0 bar and the temperature to 80°C during desorption. The flow rate of the N2 / CO2 mixed gas was set to 0.1 L / min at all stages. Figure 17 shows a schematic scheme of the PSA cycle.

[0065] Figure 18 shows the breakthrough characteristics of the first and second cycles of the PTSA cycle in gas separation unit A. The PTSA cycle consistently exhibits high working capacity throughout all consecutive adsorption cycles. That is, as shown in Figure 18, the adsorption capacity was almost completely maintained from cycle to cycle, showing a constant adsorption amount, and no decrease in adsorption amount was observed.

[0066] As shown in Example 4, a standard PSA can be successfully used for CO2 adsorption, but this is not the only example. More importantly, the superior thermal properties suggest that the adsorption rate can be increased during the PSA cycle compared to a standard packed adsorption bed. Furthermore, as shown in Example 5, the use of PTSA demonstrated that the potential adsorption capacity of the gas separation agent could be fully realized in each cycle. This proves that the gas separation unit of the present invention can be used efficiently in both PSA and PTSA cycles.

[0067] Example 6 Fabrication of Gas Separation Unit D A gas separator was obtained by directly supporting HKUST-1 on a copper type B monolith (thermal conductivity 398 W / m·K) shown in Figure 19, which served as the base material. Direct support of HKUST-1 onto the base material was carried out in the same manner as in Example 3. The obtained gas separator was housed in an outer cylinder to fabricate a gas separation unit D.

[0068] Gas separation unit D can directly support the gas separation agent without using a binder, thus suppressing coating of the gas separation agent by the binder. As a result, the gas separation agent is supported on the substrate without reducing the amount of adsorption. Figure 20 shows the adsorption isotherm of gas separation unit D.

[0069] 《Pressure loss simulation of gas separation unit D》 The pressure drop of gas separation unit D was determined by CFD simulation. The simulation results were compared with those of a standard packed column using Elgin's equation (see below). For the standard packed column, spherical particles with a diameter of 1.5 mm (1 mm glass bead substrate + 0.5 mm gas separation agent) were used with a random distribution (porosity ~0.4).

number

[0070] The results shown in Figure 21 suggest that gas separation unit D can provide less pressure loss compared to a conventional packed column with the same shape settings (length = 50 mm, inner diameter = 9 mm). This is thought to be because the gas flow path inside the gas separation unit is designed with a suitable shape. [Explanation of Symbols]

[0071] 100 Gas Separation Units 110 Gas Separator 120 Outer cylinder 6. Air intake 7 Exhaust vent 8 Lead wires 9. Probe (near the air intake / center) 10. Probe (near the air intake / surface) 11. Probe (near exhaust port / center) 12. Probe (near exhaust port / surface)

Claims

1. It has a gas separator and an outer cylinder, The gas separator comprises a substrate having a thermal conductivity of 45 W / m·K or more, and a gas separator supported on the substrate. The gas separator is housed in the outer cylinder so as to form a gas flow path. Gas separation unit.

2. The gas separation unit according to claim 1, wherein the substrate includes at least one selected from copper, aluminum, iron, and galvanized steel sheet.

3. The gas separation unit according to claim 1, wherein the gas separator has a honeycomb shape.

4. The gas separation unit according to claim 1, wherein the gas separator has at least one shape selected from wire-like and tape-like.

5. The gas separation unit according to claim 1, wherein the gas separation agent comprises a porous coordination polymer, a zeolite, or a combination thereof.

6. The aforementioned gas separation agent is CO ２ The gas separation unit according to claim 5, which adsorbs 20 mL or more of gas per gram of gas separation agent at 0°C and 1 atmosphere.

7. The gas separation unit according to claim 1, wherein the gas separation agent comprises a gate-type porous coordination polymer.

8. The aforementioned gas separation agent is CO ２ The gas separation unit according to claim 7, which adsorbs gas at 0°C and less than 1 atmosphere.

9. The gas separation unit according to claim 1, wherein the gas separator does not have a binder.

10. A gas separation apparatus comprising a gas separation unit according to any one of claims 1 to 9.

11. A gas separation method comprising passing two or more mixed gases through a gas separation unit according to any one of claims 1 to 9, and adsorbing and separating a specific gas from the mixed gas.

12. A gas separation method comprising passing two or more mixed gases through a gas separation unit according to any one of claims 1 to 9, and manipulating at least one of the pressure and temperature to adsorb and separate a specific gas from the mixed gas.

13. A gas separation method comprising passing two or more mixed gases through a gas separation unit according to any one of claims 1 to 9, and manipulating the temperature to adsorb and separate a specific gas from the mixed gas.

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