Gas adsorption / desorption module, operation method, gas adsorption / desorption device, and method for concentrating, separating, recovering or purifying gas

Abstract

To selectively heat and cool an adsorbent in a gas adsorption / desorption module.MEANS FOR ACHIEVING THE PURPOSE: The gas adsorption / desorption module includes a carbon fiber having a continuous porous structure, an electrode connected to the carbon fiber, a power supply device, and a container with a gas inlet / outlet for housing them. Wherein the carbon fibers have a hollow structure, and a mechanism for applying a pressure difference of 0.05 MPa or more between the hollow portion and the outside is provided.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a gas adsorption / desorption module, an operating method, a gas adsorption / desorption device, and a method for concentrating, separating, recovering, or purifying gas. [Background technology]

[0002] There are two methods for separating specific gas components from a mixed gas containing multiple components by adsorbing them onto an adsorbent material, from gas components that are difficult to adsorb: pressure swing adsorption (PSA) and temperature swing adsorption (TSA). TSA has the advantage of being simpler in terms of the device configuration than PSA and requiring less purge gas when recovering the adsorbed gas, but it is known to have the disadvantage of low device efficiency due to the large amount of energy consumed to heat the device and the long heating and cooling times required.

[0003] The drawback of TSA is that the heat transfer heating commonly used in industry heats and cools not only the adsorbent but also the surrounding structures. For this reason, methods have been proposed for selectively heating only the adsorbent, such as using microwaves (e.g., Patent Document 1) or passing an electric current through a conductive adsorbent (e.g., Patent Document 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-5527 [Patent Document 2] Japanese Patent Application Laid-Open No. 2002-224562 Summary of the Invention [Problem to be solved by the invention]

[0005] Patent Document 1 discloses a method for irradiating silicon carbide sintered bodies with microwaves to heat and desorb the adsorbent during an adsorption / desorption process. However, using microwaves as a heating method requires not only an expensive microwave generator, but also special consideration for the size, shape, and material of the absorption tower and adsorbent support, limiting its practical industrial application. Patent Document 2 discloses a method for reducing the electrical resistance between the electrode and the activated carbon fiber sheet to prevent excessive electrical resistance and current bias caused by the small contact area between the electrode and the fiber, which can be a problem when applying current to the activated carbon fiber sheet for regeneration. While this invention solves the problem of excessive electrical resistance to some extent, it does not fundamentally solve the problem of abnormal heat generation due to current bias, which can be fatal for industrial use. Furthermore, in both inventions, it was theoretically difficult to provide a mechanism for cooling the adsorbent during the adsorption process to increase the adsorption capacity.

[0006] SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems and to selectively heat and cool the adsorbent in a gas adsorption / desorption module. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention has the following configuration.

[0008] [1] A gas adsorption / desorption module comprising: carbon fiber having a continuous porous structure; electrodes and a power supply connected to the carbon fiber; and a container with a gas inlet and outlet for housing these.

[0009] [2] A gas adsorption / desorption module, characterized in that the carbon fiber has a hollow structure and is equipped with a mechanism for applying a pressure difference of 0.05 MPa or more between the hollow portion and the outside.

[0010] [3] A method for operating a gas adsorption / desorption module according to [1], comprising the step of passing an electric current through the electrodes to heat the carbon fiber and desorb the adsorbate.

[0011] [4] A method for operating a gas adsorption / desorption module according to [2], comprising the steps of passing an electric current through the electrodes to heat the carbon fiber and desorb the adsorbate, and applying a pressure difference between the hollow portion and the outside to cool the carbon fiber and adsorb the adsorbate.

[0012] [5] A gas adsorption / desorption device for concentrating, separating, recovering, or purifying gas, comprising the gas adsorption / desorption module according to [1].

[0013] [6] A method for concentrating, separating, recovering or purifying a gas using the apparatus described in [5]. [Effects of the Invention]

[0014] The gas adsorption / desorption module of the present invention allows for safe electrical conduction without causing poor contact between the electrodes and the fibers or current imbalance. Furthermore, by creating a pressure difference between the hollow portion of the hollow fibers and the outside, it is possible to selectively heat and cool only the fibers, which act as the adsorbent, thereby reducing energy consumption and improving device efficiency. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a schematic diagram showing a cross section including a gas inlet / outlet port, illustrating one embodiment of a gas adsorption / desorption module of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0016] The present invention will be described below with reference to examples, but the present invention should not be construed as being limited to these examples.

[0017] (Heating mechanism) In the adsorption step of the gas adsorption / desorption module of the present invention, a specific component (adsorbate) of the raw material gas flowing into the container is adsorbed by the carbon fiber having an open porous structure as the adsorbent, and the remaining components are discharged to the outside of the container as a residual gas. In the desorption step, the adsorbate is desorbed from the carbon fiber having an open porous structure and discharged to the outside of the container as a recovered gas.

[0018] The carbon fiber having a continuous porous structure in the present invention is defined in JIS L0204-2 (2020). Carbon fibers are used in a variety of applications, primarily as structural materials, due to their characteristics such as strength, elastic modulus, chemical and thermal stability, high electrical conductivity, and a low specific gravity compared to metals.

[0019] The gas adsorption / desorption module of the present invention includes carbon fiber having a continuous porous structure, electrodes and a power supply connected to the carbon fiber, and a container with a gas inlet and outlet that houses these. Here, the "continuous porous structure" refers to a structure in which the pores (voids) in the carbon skeleton are continuous. This can be confirmed by observing the surface of a cross section of a sample, which has been sufficiently cooled in liquid nitrogen, cut with tweezers, using a scanning electron microscope to see that the voids in the carbon skeleton are continuous. The continuous porous structure ensures a large specific surface area even for carbon fibers with a fiber diameter of 0.1 μm or greater.

[0020] In the gas adsorption / desorption module of the present invention, the carbon fiber having a continuous porous structure preferably has a co-continuous structure. Here, the term "co-continuous structure" refers to a structure in which the branches and pores of the carbon skeleton are each continuous and regularly intertwined in a three-dimensional manner. Specifically, when a sample sufficiently cooled in liquid nitrogen is cut with tweezers and the cross section is observed under a scanning electron microscope, the branches and voids of the carbon skeleton are each continuous and intertwined. By using carbon fibers having a co-continuous structure, it is possible to ensure a large specific surface area while maintaining mechanical strength in tension, compression, bending, and the like.

[0021] In the gas adsorption / desorption module of the present invention, the carbon fiber having a continuous porous structure preferably has a fiber diameter of 0.1 μm or more and 1000 μm or less. A fiber diameter of 0.1 μm or more can increase the contact area between the fiber and the electrode, thereby reducing the apparent electrical resistance between the fiber and the electrode. Furthermore, increasing the cross-sectional area per fiber can reduce current leakage from one fiber to another, allowing current to flow uniformly through each fiber. The fiber diameter is more preferably 1 μm or more, even more preferably 10 μm or more, and even more preferably 100 μm or more. Furthermore, a carbon fiber diameter of 1000 μm or less facilitates gas diffusion into the fiber. The fiber diameter is more preferably 600 μm or less, even more preferably 400 μm or less. The fiber diameter of carbon fiber is determined by observing a cross section of a sample sufficiently cooled in liquid nitrogen, cut with tweezers, under a scanning electron microscope, and doubling the square root of the value obtained by dividing the cross-sectional area of ​​the fiber (including the area of ​​the hollow portion, if any) by pi. The carbon fiber is cut out on a plane perpendicular to the longitudinal direction, and the observation angle is adjusted so that the outer surface of the carbon fiber is not reflected as much as possible during observation. Five or more carbon fibers are cut out, and the average fiber diameter of the obtained carbon fibers, expressed to two significant digits, is used as the fiber diameter of the carbon fiber.

[0022] Furthermore, carbon fibers having a continuous porous structure are preferably hollow. A hollow carbon fiber allows gas to diffuse easily throughout the fiber. The hollow ratio of carbon fibers is preferably 3% or more and 50% or less. A high hollow ratio of carbon fibers facilitates gas diffusion. The hollow ratio of carbon fibers is more preferably 5% or more. On the other hand, a low hollow ratio of carbon fibers improves spinnability and fiber strength. The hollow ratio of carbon fibers is more preferably 30% or less, and even more preferably 20% or less. Here, the hollow ratio is the ratio of the area of ​​hollow portions to the cross-sectional area of ​​the carbon fiber (including the area of ​​hollow portions). A sample sufficiently cooled in liquid nitrogen is cut with tweezers, the cross-section is observed under a scanning electron microscope, and the value of the area of ​​the hollow portions (if multiple hollow portions are observed in the cross-section, the total area of ​​those hollow portions) is divided by the value of the cross-sectional area of ​​the fiber (including the area of ​​hollow portions). In this case, the carbon fibers are cut at a plane perpendicular to the longitudinal direction, and the observation angle is adjusted so that the outer surface of the carbon fibers is not reflected as much as possible. Five or more carbon fibers were cut out, and the average hollowness value obtained was expressed to two significant figures and used as the hollowness value of the carbon fiber.

[0023] The cross-sectional shape of the carbon fiber having a continuous porous structure and the hollow portion is not particularly limited, and may be circular, elliptical, polygonal, or any other shape. Furthermore, the carbon fiber may have multiple hollow portions, or may have branches or ends.

[0024] In the gas adsorption / desorption module of the present invention, the bending radius of the carbon fiber having a continuous porous structure is preferably 0.1 cm or more and 100 cm or less. A bending radius of 0.1 cm or more improves the shape stability of the carbon fiber, minimizing contact between the carbon fibers that can cause biased current. The bending radius of the carbon fiber is more preferably 0.2 cm or more, and even more preferably 0.5 cm or more. On the other hand, a bending radius of 100 cm or less allows the carbon fiber to bend within the module when it stretches in a humidified environment, thereby preventing breakage of the carbon fiber. The bending radius is more preferably 10 cm or less, and even more preferably 5 cm or less.

[0025] The bending radius of carbon fiber can be determined by sampling at least 10 cm of carbon fiber from a module, wrapping the sampled carbon fiber around a cylinder at least 360° so that the length is the shortest, and determining the radius of the cylinder at which the carbon fiber does not break. If a support or coating layer is attached to the carbon fiber, the bending radius of the carbon fiber, including the support and coating layer, is considered to be the bending radius of the carbon fiber. Five or more carbon fibers are cut out, and the average radius of the resulting cylinders, expressed to one significant digit, is considered to be the bending radius of the carbon fiber.

[0026] In the gas adsorption / desorption module of the present invention, the carbon fiber having a continuous porous structure is preferably in the form of a woven, knitted, or braided fabric. By using the carbon fiber in the form of a woven, knitted, or braided fabric, it is possible to pack more fibers into the limited volume of the module container and to distribute the source gas throughout the container. Furthermore, in the gas adsorption / desorption module of the present invention, the packing rate of the carbon fiber housed in the module is preferably 5% or more and 95% or less. A carbon fiber packing rate of 5% or more makes it possible to increase the specific surface area per unit volume of the module and process a large amount of source gas. The carbon fiber packing rate is more preferably 10% or more, and even more preferably 15% or more. On the other hand, if the packing rate of the carbon fiber housed in the module is low, the gaps through which the source gas passes become wider, thereby reducing pressure loss within the module. The carbon fiber packing rate is more preferably 70% or less, and even more preferably 50% or less. Here, the filling rate F is the ratio of the volume of carbon fiber (including the volume of the hollow part) to the volume of the module container (limited to the volume of the part that can be filled with carbon fiber), and is calculated using the following formula.

[0027] F=M / (D×V) Here, M is the mass of the carbon fiber packed in the module, and V is the volume of the module container (limited to the volume of the part that can be packed with carbon fiber). The density D of the carbon fiber (density ignoring the voids in the hollow part) is calculated using the following formula.

[0028] D=d / ((R / 2)^2×π) Here, R is the fiber diameter of the carbon fiber, and π is the ratio of the circumference of the fiber to its diameter. The linear density d of the carbon fiber is obtained by sampling multiple carbon fibers from the module so that the total length is 50 cm or more, and dividing the mass of the sampled carbon fibers by the fiber length.

[0029] In the gas adsorption / desorption module of the present invention, the carbon fiber having a continuous porous structure preferably has a resistivity of 1.0 Ω·m or less. A resistivity of 1.0 Ω·m or less allows a current to be passed that generates enough heat to heat the carbon fiber even at a low voltage. The upper limit of the resistivity is more preferably 0.50 Ω·m or less, and even more preferably 0.10 Ω·m or less. Here, the electrical resistivity of the carbon fiber is measured using a four-terminal method. A carbon fiber of 10 cm or more is cut from the fabricated module and fixed on a flat surface. Four arbitrary points (referred to as a, b, c, and d, respectively) are connected to four pieces of aluminum tape (referred to as A, B, C, and D, respectively) using silver paste and copper wire. Of the four pieces of aluminum tape, B and C are connected to the current measurement terminals of a potentiostat (HA-151A, manufactured by Meiden Hokuto Co., Ltd.), and A and D are connected to the voltage measurement terminals. Then, the current-voltage characteristics of the carbon fiber when a current of 0 to 0.01 A is passed through it are measured using a potentiostat, and the electrical resistivity ρ of the carbon fiber is calculated using the following formula.

[0030] ρ=(I / V)×((R / 2) 2 -(r / 2) 2 )×π / L where I is the current, V is the voltage, R is the outer diameter of the carbon fiber, r is the diameter of the hollow part of the carbon fiber (0 if there is no hollow part), π is the circumference constant, and L is the length of the carbon fiber between b and c.

[0031] Five or more carbon fibers are cut out, and the average of the obtained electrical resistivities expressed to two significant figures is taken as the electrical resistivity.

[0032] The gas adsorption / desorption module of the present invention preferably includes, at least in part, a member A made of a material having an insulating property 100 times or more the electrical resistivity of the carbon fiber. The member A reduces current leakage from one fiber to another and allows current to flow uniformly through each fiber. The ratio of the electrical resistivity of the member A to the electrical resistivity of the carbon fiber is more preferably 500 times or more, and even more preferably 1000 times or more. The material of the member A is not particularly limited, but examples include polyester, nylon, polyolefin, polyacetal, thermoplastic elastomer, fluororesin, epoxy resin, polyimide resin, urethane resin, and silicone.

[0033] Furthermore, the component A is preferably arranged so as to be in contact with the carbon fiber. The shape of the component A and the state of contact with the carbon fiber are not particularly limited, but examples include a form in which the component A covers the carbon fiber, and a form in which the component A is placed in the gaps between multiple threads of carbon fiber. Here, "covered" refers to a form in which, in appearance, all or part of the outer surface of the carbon fiber is covered with a resin composition or the like. Examples of such a form include a form in which a resin composition or the like in the form of particles or filler is attached to part of the surface of the carbon fiber, and a form in which a resin composition or the like in the form of fiber is spirally wrapped around the carbon fiber, which can impart insulating properties to the surface of the carbon fiber without impairing fluid permeability.

[0034] In the gas adsorption / desorption module of the present invention, the carbon fiber having a continuous porous structure and the electrode are preferably bonded using a metal or a conductive resin. Bonding using a metal or a conductive resin increases the contact area between the fiber and the electrode, thereby reducing the apparent electrical resistance between the fiber and the electrode. Examples of metals include solder, tin, zinc, aluminum, and silver. Examples of conductive resins include polyacetylene, polyparaphenylene, polythiophene, polyaniline, polypyrrole, polyparaphenylene vinylene, poly-3,4-ethylenedioxythiophene, poly-4-styrene sulfonate, and copolymers thereof. Examples of conductive resins include epoxy resins, polyimide resins, urethane resins, and silicones to which metals such as nickel, silver, gold, and zinc or carbon materials such as carbon black, carbon nanotubes, and graphene have been added.

[0035] In the gas adsorption / desorption module of the present invention, the material of the electrodes is not particularly limited, and examples thereof include gold, silver, copper, aluminum, tungsten, molybdenum, and other metals and alloys thereof, as well as graphite. The material of the container is also not particularly limited, and examples thereof include stainless steel, aluminum, glass, and acrylic resin. When a conductive material is used for the container, it is desirable to take measures such as covering it with an insulating material to prevent the current flowing through the carbon fiber from leaking into the container. The shape of the container is also not particularly limited, and any shape such as a cylindrical shape or a rectangular parallelepiped shape can be used.

[0036] (cooling mechanism) In one embodiment of the gas adsorption / desorption module of the present invention, carbon fibers having a continuous porous structure can be provided with a hollow structure and a mechanism for applying a pressure difference of 0.05 MPa or more between the hollow portion and the outside. When gas passes through the carbon fibers under a pressure difference across the hollow carbon fibers, the gas is cooled by the Joule-Thomson effect, and the carbon fibers are also cooled, promoting the adsorption of the adsorbate in the source gas. Examples of methods for applying a pressure difference between the hollow portion of the fiber and the outside include reducing the pressure in either the hollow portion or the outside, or pressurizing either the hollow portion or the outside, or both. Applying a pressure difference so that the pressure outside is higher than that inside the hollow portion allows the cooled gas to flow through the hollow portion of the carbon fiber, enhancing the cooling effect of the gas on the carbon fiber. On the other hand, when applying a pressure difference so that the pressure in the hollow portion is higher than that outside when pressurizing either the outside or the hollow portion to create a pressure difference, the energy required for pressurization is reduced. Therefore, a preferred method can be selected based on the adsorption characteristics of the target gas to be adsorbed by the carbon fiber, the device configuration, scale, etc.

[0037] The greater the pressure difference between the hollow space and the outside, the greater the gas permeability and the cooling effect due to the Joule-Thomson effect. The pressure difference between the hollow space and the outside is more preferably 0.5 MPa or more, and even more preferably 1 MPa or more.

[0038] (Gas adsorption / desorption device) The gas adsorption / desorption device of the present invention is a device including the gas adsorption / desorption module of the present invention. The gas adsorption / desorption device of the present invention can include a raw material gas pretreatment device, a residual gas recovery device, and a recovered gas recovery device in addition to the gas adsorption / desorption module. The raw material gas pretreatment device is a device for removing impurities from the raw material gas before separation and adjusting the composition. The residual gas recovery device is a device for recovering the residual gas from which the adsorbates have been removed from the raw material gas, and for further purifying the residual gas as needed, storing the residual gas in a tank, or supplying it to another device. The recovered gas recovery device is a device for recovering the recovered gas containing the adsorbates desorbed from the adsorbent, and for further purifying the residual gas as needed, storing the residual gas in a tank, or supplying it to another device.

[0039] The gas adsorption / desorption device of the present invention preferably comprises a plurality of gas adsorption / desorption modules of the present invention. By providing a plurality of gas adsorption / desorption modules, while a desorption step is being performed in one gas adsorption / desorption module, adsorption can be performed in another gas adsorption / desorption module, thereby enabling continuous processing of the source gas.

[0040] The compositions of the raw material gas and the gas to be adsorbed that are treated by the gas adsorption / desorption apparatus of the present invention are not particularly limited, but examples of the gas to be adsorbed include acidic gases such as carbon dioxide, nitrogen oxides, and sulfur compounds. Here, "nitrogen oxides" refers to oxides of nitrogen, such as nitric oxide, nitrogen dioxide, and nitrous oxide. "Sulfur compounds" refers to compounds of sulfur, such as hydrogen sulfide, sulfur dioxide, and sulfur trioxide. The gas to be adsorbed need only be in a gaseous state or dispersed in the raw material gas at the raw material gas temperature during operation of the apparatus, and does not need to be in a gaseous state at room temperature.

[0041] Examples of feedstock gases include gases containing 60% or more by volume of a combination of gases selected from the group consisting of methane and carbon dioxide, hydrogen and carbon dioxide, and nitrogen, oxygen, carbon dioxide, nitrogen oxides, and sulfur compounds. Specific examples include natural gas, biogas, exhaust gas, and the atmosphere. Here, "natural gas" refers to gas extracted from the earth and composed primarily of low-molecular-weight hydrocarbons, while "biogas" refers to gas generated by biological activity and composed primarily of low-molecular-weight hydrocarbons. "Exhaust gas" refers to gas emitted from internal combustion engines, boilers, furnaces, and other sources, as well as gas generated in industrial processes and released into the atmosphere. The feedstock gas does not need to be gaseous at room temperature; it is sufficient that its main components are in a gaseous state at the feedstock gas temperature during operation of the equipment. Furthermore, the feedstock gas may contain liquid components such as tiny droplets or solid components such as dust. [Example]

[0042] The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to these. Evaluations in each example and comparative example were carried out by the following methods. In these examples, pressures are expressed in absolute pressure.

[0043] (carbon fiber diameter and hollow diameter) Carbon fibers of 1 cm or more were cut from the fabricated module, thoroughly cooled in liquid nitrogen, and then cut with tweezers. The cross sections of the carbon fibers were observed using a scanning electron microscope (VHX-7000, Keyence Corporation). The carbon fibers were cut in a plane perpendicular to the longitudinal direction. The observation angle was adjusted so that the outer surface of the carbon fiber was not reflected as much as possible. The fiber diameter was calculated by doubling the square root of the cross-sectional area of ​​the fiber (including the area of ​​the hollow portion, if present) divided by pi. The diameter of the hollow portion was calculated by doubling the square root of the area of ​​the hollow portion divided by pi. Five or more carbon fibers were cut, and the average fiber diameters and hollow portion diameters of the obtained carbon fibers, expressed to two significant digits, were used as the fiber diameter and hollow portion diameter of the carbon fiber.

[0044] (carbon fiber hollow ratio) The cross section of the carbon fiber was observed with a scanning electron microscope using the same procedure as in the section on fiber diameter of carbon fiber, and the hollow ratio was determined by dividing the area of ​​the hollow part (if multiple hollow parts were observed in the cross section, the total area of ​​those parts) by the cross-sectional area of ​​the fiber (the area including the hollow part). Five or more carbon fibers were cut out, and the average hollow ratio obtained was expressed to two significant digits, which was taken as the hollow ratio of the carbon fiber.

[0045] (Carbon fiber bending radius) Carbon fiber of 10 cm or more was cut from the fabricated module, and the cut carbon fiber was wrapped around a cylinder at least 360° so that the length was the shortest. The radius of the cylinder at which the carbon fiber did not break was determined. Five or more carbon fibers were cut, and the average value of the radius of the obtained cylinders, expressed to one significant digit, was used as the bending radius of the carbon fiber. Note that if a support or coating layer is attached to the carbon fiber, the bending radius of the carbon fiber including the support or coating layer is considered to be the bending radius of the carbon fiber.

[0046] (electrical resistivity of carbon fiber) A length of carbon fiber of at least 10 cm was cut from the fabricated module and fixed on a flat surface. Four randomly selected points (referred to as a, b, c, and d) were connected to four pieces of aluminum tape (referred to as A, B, C, and D) using silver paste and copper wire. Of the four pieces of aluminum tape, B and C were connected to the current measurement terminals of a potentiostat (HA-151A, manufactured by Meiden Hokuto Co., Ltd.), and A and D were connected to the voltage measurement terminals. The current-voltage characteristics of the carbon fiber were measured using the potentiostat when a current of 0 to 0.01 A was passed through it, and the electrical resistivity ρ of the carbon fiber was calculated using the following equation.

[0047] ρ=(I / V)×((R / 2) 2 -(r / 2) 2 )×π / L where I is the current, V is the voltage, R is the diameter of the carbon fiber, r is the diameter of the hollow part of the carbon fiber (0 if there is no hollow part), π is the circumference constant, and L is the length of the carbon fiber between b and c.

[0048] Five or more carbon fibers were cut out, and the average of the obtained electrical resistivities was expressed to two significant figures and used as the electrical resistivity of the carbon fiber.

[0049] (carbon fiber temperature) An opening was made in the fabricated module, and a digital radiation thermometer (FT-H10, manufactured by Keyence Corporation) was installed to measure the temperature of the carbon fiber. The temperature was measured five times under the same conditions, and the average value of the obtained temperature, expressed to two significant digits, was taken as the temperature of the carbon fiber.

[0050] (Production Example 1) Ten parts by mass of polyacrylonitrile (PAN) (MW 150,000) manufactured by Polysciences, 10 parts by mass of polyvinylpyrrolidone (PVP) (MW 40,000) manufactured by Sigma-Aldrich, and 80 parts by mass of dimethyl sulfoxide (DMSO) manufactured by Wako Pure Chemical Industries, Ltd. were mixed and stirred at 100°C to prepare a spinning dope.

[0051] The obtained spinning solution was cooled to 25°C, and then a concentric triple spinneret was used to simultaneously discharge an 80 wt% aqueous DMSO solution from the inner tube, the spinning solution from the middle tube, and a 90 wt% aqueous DMSO solution from the outer tube, and then the resultant was introduced into a coagulation bath of pure water at 25°C and wound up on a roller to obtain a raw fiber. The obtained raw fiber was washed with water and then dried in a circulating dryer at 25°C for 24 hours to produce a precursor of a porous carbon support for hollow fibers.

[0052] The porous carbon support precursor was then passed through an electric furnace at 250°C and heated in an air atmosphere for 1 hour to perform infusibilization treatment. The infusibilized yarn was then carbonized in an inert atmosphere at 1300°C to produce the porous carbon fiber of Production Example 1.

[0053] (Production Example 2) Porous carbon fibers of Production Example 2 were produced in the same manner as in Production Example 1, except that the carbonization temperature of the infusible yarn was changed from 500°C to 900°C.

[0054] (Production Example 3) Porous carbon fibers of Production Example 3 were produced in the same manner as in Production Example 1, except that the carbonization temperature of the infusible yarn was changed from 500°C to 750°C.

[0055] (Production Example 4) The porous carbon fiber of Production Example 1 was used as a core yarn, and Toyoflon (registered trademark) (manufactured by Toray Industries, Inc.), a PTFE fiber with a total fineness of 220 tex, was wound around it at a pitch of 1 cm in the Z direction to produce the covered porous carbon fiber of Production Example 4, in which the PTFE fiber was spirally wound.

[0056] Example 1 One hundred porous carbon fibers from Production Example 1 were bundled and placed inside an acrylic pipe (inner diameter 5 mm) with an inlet and outlet for the raw material gas. Each end of the acrylic pipe was potted with epoxy resin containing carbon black. Electrodes were then attached to the epoxy resin at both ends using solder, and the module was connected to a power supply to create a gas adsorption / desorption module. The distance between the epoxy resin at both ends was 30 cm.

[0057] As a result of evaluation using the above-mentioned method, the porous carbon fiber had a fiber diameter of 220 μm, a hollow ratio of 11%, a bending radius of 10 cm or less, and an electrical resistivity of 7.3 × 10 -5 The resistance was Ω·m.

[0058] When a voltage of 1.5 V was applied between the electrodes at both ends of the module for 10 seconds, the porous carbon fiber was heated to 180°C.

[0059] Example 2 A gas adsorption / desorption module of Example 2 was produced in the same manner as in Example 1, except that the porous carbon fiber of Production Example 2 was used instead of the porous carbon fiber of Production Example 1.

[0060] As a result of evaluation using the above-mentioned method, the porous carbon fiber had a fiber diameter of 230 μm, a hollow ratio of 10%, a bending radius of 10 cm or less, and an electrical resistivity of 2.7 × 10 -2 The resistance was Ω·m.

[0061] When a voltage of 1.5 V was applied between the electrodes at both ends of the module for 30 seconds, the porous carbon fiber was heated to 150°C.

[0062] Example 3 A gas adsorption / desorption module of Example 2 was produced in the same manner as in Example 1, except that the covered porous carbon fiber of Production Example 4 was used instead of the porous carbon fiber of Production Example 1.

[0063] As a result of evaluation using the above-mentioned method, the bending radius of the covered porous carbon fiber was 10 cm or less, and the electrical resistivity was 2.6 × 10 -2 The resistance was Ω·m.

[0064] When a voltage of 1.5 V was applied between the electrodes at both ends of the module for 10 seconds, the porous carbon fiber was heated to 170°C.

[0065] Example 4 After producing the gas adsorption / desorption module of Production Example 1, the carbon fiber exposed between the potting portions on both ends of the module was immersed in a 10 wt % hexane solution of silicone (Silgard (registered trademark), manufactured by DuPont-Toray Co., Ltd.) (hereinafter referred to as PDMS solution) until the outer surface of the fiber was fully immersed in the PDMS solution. The PDMS solution was then removed, and the module was dried and heated in an oven at 70°C for 30 minutes to produce a gas adsorption / desorption module containing carbon fiber having a silicone coating layer on at least a portion of its surface.

[0066] As a result of evaluation using the above-mentioned method, the bending radius of the silicone-coated porous carbon fiber was found to be 10 cm or less.

[0067] When a voltage of 1.5 V was applied between the electrodes at both ends of the module for 10 seconds, the porous carbon fiber was heated to 180°C.

[0068] Example 5 In the adsorption / desorption module of Example 1, after the epoxy resin had hardened, the potting portion at one end was cut with a rotary saw to open the hollow portion of the carbon fiber, and the opening was connected to an exhaust blower.

[0069] When air at a temperature of 25°C and a pressure of 2.0 MPa was supplied as a raw material gas into the container, the temperature of the porous carbon fiber was cooled to 15°C after 10 seconds.

[0070] Example 6 In the adsorption / desorption module of Example 5, air at a temperature of 25°C and a pressure of 0.5 MPa was supplied as a raw material gas into the container, and the temperature of the porous carbon fiber was cooled to 17°C after 30 seconds.

[0071] (Comparative Example 1) A gas adsorption / desorption module of Example 3 was produced in the same manner as in Example 1, except that the porous carbon fiber of Production Example 3 was used instead of the porous carbon fiber of Production Example 1.

[0072] As a result of evaluation using the above-mentioned method, the porous carbon fiber had a fiber diameter of 250 μm, a hollow ratio of 10%, a bending radius of 10 cm or less, and an electrical resistivity of 3.0 × 10 5 The resistance was Ω·m.

[0073] When a voltage of 20 V was applied between the electrodes at both ends of the module, no change in temperature was observed.

[0074] (Comparative Example 2) In the adsorption / desorption module of Example 4, when air at a temperature of 25° C. and a pressure of 0.14 MPa was supplied as a raw material gas into the container, no change in temperature was observed. [Explanation of symbols]

[0075] 1: Gas adsorption / desorption module 2: Porous hollow carbon fiber 3: Electrode 4: Gas inlet 5: Gas outlet 6: Power supply 7: Blower

Claims

1. A gas adsorption module comprising: a carbon fiber having a continuous porous structure; an electrode and a power supply connected to the carbon fiber; and a container with a gas inlet and outlet for housing these.

2. 2. The gas adsorption module according to claim 1, wherein the carbon fibers have a bicontinuous structure.

3. 2. The gas adsorption module according to claim 1, wherein the fiber diameter of the carbon fibers is 10 μm or more and 1000 μm or less.

4. 2. The gas adsorption module according to claim 1, wherein the carbon fibers are in the form of a woven fabric, a knitted fabric or a braided fabric.

5. 2. The gas adsorption module according to claim 1, which comprises, at least in part, a member A made of a material having an insulating property at least 100 times the electrical resistivity of the carbon fiber.

6. 6. The gas adsorption module according to claim 5, wherein the carbon fiber and the member A are arranged so as to be in contact with each other.

7. 2. The gas adsorption module according to claim 1, wherein the carbon fibers and the electrodes are bonded together using a metal or a conductive resin.

8. 2. The gas adsorption / desorption module according to claim 1, wherein the carbon fiber has a hollow structure.

9. 9. The gas adsorption / desorption module according to claim 8, further comprising a mechanism for applying a pressure difference of 0.05 MPa or more between the hollow portion of the hollow carbon fiber and the outside.

10. 2. The method for operating a gas adsorption / desorption module according to claim 1, further comprising the step of passing an electric current through the electrodes to heat the carbon fibers and desorb the adsorbate.

11. 10. A method for operating a gas adsorption / desorption module according to claim 9, comprising the steps of: passing an electric current through the electrodes to heat the carbon fibers and desorb the adsorbate; and applying a pressure difference between the hollow portion and the outside to cool the carbon fibers and adsorb the adsorbate.

12. A gas adsorption / desorption device for concentrating, separating, recovering or purifying gas, comprising the gas adsorption / desorption module according to claim 1.

13. 13. The gas adsorption / desorption device according to claim 12, wherein carbon dioxide, nitrogen oxides, or sulfur compounds are adsorbed in a raw material gas that is a mixed gas.

14. 14. The gas adsorption / desorption device according to claim 13, wherein the raw material gas contains 60% by volume or more of a combination of gases selected from the group consisting of [methane and carbon dioxide], [hydrogen and carbon dioxide], and [nitrogen, oxygen, carbon dioxide, a nitrogen compound, and a sulfur compound].

15. 15. The gas adsorption / desorption device according to claim 14, wherein the raw material gas is a gas selected from the group consisting of natural gas, biogas, exhaust gas, and atmospheric air.

16. 13. A method for concentrating, separating, recovering or purifying gases using the device of claim 12.

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