Gas phase reaction reactor and method for producing methane or methanol

Abstract

To provide a reactor that can achieve high reaction efficiency.SOLUTION: A reactor for vapor phase reaction includes independently a catalyst complex 2 and a gas separation film 3, wherein the catalyst complex has a fibrous structure, with its specific surface area of 10 m2 / g or more, and the gas separation film has a fibrous structure.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a reactor for a gas phase reaction and a method for producing methane or methanol using the reactor for a gas phase reaction. [Background technology]

[0002] Generally, gas-phase reactions are carried out by introducing raw material gas into a gas-phase reaction reactor (hereinafter sometimes simply referred to as a "reactor"). A catalyst is used as needed to obtain the target product from the raw material. To increase the yield of a gas-phase reaction, it is necessary to improve the reaction rate; however, there is an upper limit to the reaction rate governed by chemical equilibrium, and in some cases, it is not possible to increase the reaction rate due to the suppression of side reactions. Furthermore, if the mixture obtained by introducing raw materials into the reactor (hereinafter referred to as the "reaction mixture") contains unreacted raw materials or by-products, a purification process is also required to separate them. Distillation, a typical purification process, requires adjusting the temperature and pressure, resulting in significant energy loss.

[0003] Therefore, in chemical processes where purification using gas separation membranes is possible, membrane reactors that integrate the reaction process and purification process have been proposed. In a membrane reactor, both a catalyst and a gas separation membrane are placed inside the reactor, and the reaction proceeds in the space where the gas separation membrane is present. At the same time, products or by-products generated in the reaction are removed from the reaction system through the separation membrane, shifting the equilibrium toward the reaction side and improving the reaction rate. Furthermore, by using the energy (pressure and heat) generated during the reaction, purification can be performed with less energy. Specifically, reactors that use gas separation membranes that selectively allow water to permeate are known (see, for example, Patent Document 1 and Patent Document 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-55970 [Patent Document 2] Japanese Patent Application Laid-Open No. 2016-117726 Summary of the Invention [Problem to be solved by the invention]

[0005] Patent Document 1 discloses a reactor for producing methanol by reacting a raw material gas containing hydrogen and carbon dioxide in the presence of a catalyst, the reactor being characterized in that the reactor is provided with a water-selective permeable membrane that selectively separates and removes water, a by-product of the reaction, from the reaction system. The reactor in Patent Document 1 is packed with a catalyst in the form of pellets.

[0006] Patent Document 2 discloses a method for carrying out a chemical equilibrium reaction of converting carbon dioxide and hydrogen using a selectively permeable membrane, in which a portion of at least one product obtained in the reaction is separated by the action of the selectively permeable membrane and removed from the reaction, characterized in that the selectively permeable membrane is made of a material having a porous structure with an average pore size of less than 0.45 nm (4.5 Å), and at least the free surface of the material is hydrophobic. [Means for solving the problem]

[0007] However, in the method of Patent Document 1, since the catalyst has a pellet-like shape, gas remains in the catalyst packed layer inside the reactor, making it difficult to quickly allow the reactants to reach the separation membrane.

[0008] Furthermore, in the method of Patent Document 2, since the metal-containing catalyst is supported on the surface of the selectively permeable membrane, it is possible to efficiently separate at least one product portion obtained in the reaction. However, since the amount of metal that can be supported on the surface of the selectively permeable membrane is limited, there is a problem that the reaction efficiency decreases.

[0009] In order to solve the above problems, the present invention mainly has the following configuration.

[0010] A reactor for a gas phase reaction that independently contains a catalyst composite and a gas separation membrane, The catalyst composite is a fibrous structure having a specific surface area of ​​10 m 2 / g or more, The gas separation membrane is a fibrous structure. [Effects of the Invention]

[0011] In the reactor of the present invention, since both the catalyst composite and the gas separation membrane have fibrous structures, it is possible to prevent gas from stagnating inside the reactor, which allows the purification process by the gas separation membrane to proceed more quickly and improves reaction efficiency. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a schematic diagram showing a cross section of one embodiment of a reactor of the present invention. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0013] The reactor of the present invention is a reactor for gas phase reactions that independently contains a catalyst composite and a gas separation membrane, and the catalyst composite is a fibrous structure having a specific surface area of ​​10 m 2 / g or more, and the gas separation membrane has a fibrous structure.

[0014] The present invention will now be described by way of example with reference to the drawings, but the present invention should not be construed as being limited to the examples shown in the drawings.

[0015] Fig. 1 shows a cross-sectional view of a reactor according to one embodiment of the present invention. Fig. 1 is a cross-sectional view of the reactor, including the gas inlet and outlet ports. Inside the reactor, a catalyst composite 2 and a gas separation membrane 3 are fixed to the reactor vessel 1 at a potting portion 8.

[0016] <Catalytic complex> The reactor of the present invention contains a catalyst composite 2. A catalyst composite refers to an object in which two or more types of materials, including at least a catalyst, are integrated, such as a material in which a catalyst support and a metal-containing catalyst are integrated, or a material in which a metal-containing catalyst and another metal-containing catalyst are integrated. In the present invention, the catalyst composite 2 is a fibrous structure. Here, a certain object is a fibrous structure if the length (maximum length) of the longest part of the object (target object) is 100 times or more the diameter of the cross section if the cross section of the target object is circular, or the maximum width of the cross section if the cross section of the target object is not circular. When a catalyst composite is composed of two or more types of materials, the individual materials constituting the catalyst composite may not be fibrous, but it is important that the catalyst composite as a whole has a fibrous structure. Because the catalyst composite has a fibrous structure, the gas flow path inside the reactor is oriented along the fiber axis, thereby enabling more efficient gas flow inside the reactor compared to using a catalyst composite in a powder or pellet form.

[0017] The catalyst composite may be disposed over the entire length of the reactor vessel 1 as shown in Figure 1 and fixed to the vessel 1 at potting portions 8 at both ends of the vessel 1. In another embodiment of the present invention, the catalyst composite may be a fibrous structure shorter than the entire length of the vessel 1, in which case it is appropriately packed into the vessel 1.

[0018] The specific surface area of ​​the catalyst composite in the reactor of the present invention is 10 m 2 / g or more. The specific surface area is 10m 2 If the specific surface area is less than 50 m / g, the contact area between the gas and the catalytic composite is small, and the chemical reaction rate of the gas decreases. 2 / g or more, and 100m 2 On the other hand, in order to maintain sufficient mechanical strength of the catalyst composite, the specific surface area of ​​the catalyst composite is preferably 1000 m 2 / g or less, and 2 / g or less is more preferable. The specific surface area of ​​the catalyst composite can be measured by the Brunauer-Emmett-Teller (BET) method. Specifically, the catalyst composite is degassed at 100°C for 60 minutes, cooled, and then measured by the BET flow method using nitrogen gas as the adsorption gas. Methods for adjusting the specific surface area of ​​the catalyst composite to a desired value include changing the fiber diameter or cross-sectional shape of the fiber, embedding fine particles inside the fiber and then removing them, and, if the catalyst composite contains carbon fiber, performing an activation treatment.

[0019] The catalyst composite preferably comprises a catalyst support and a metal-containing catalyst. When the catalyst composite comprises a catalyst support and a metal-containing catalyst, the metal-containing catalyst is supported on the surface or inside of the catalyst support, and the catalyst support plays a role in immobilizing the metal-containing catalyst and maintaining the shape of the catalyst composite as a whole, while the metal-containing catalyst plays a role in substantially catalyzing the target chemical reaction.

[0020] When the catalyst composite is composed of a catalyst carrier and a metal-containing catalyst, the catalyst carrier preferably has a fibrous structure (hereinafter, a catalyst carrier having a fibrous structure will be referred to as a "fibrous catalyst carrier"). When the catalyst carrier has a fibrous structure, the shape of the catalyst composite can be maintained in a fibrous form. Examples of materials for the fibrous catalyst carrier include polyester, nylon, polyolefin, fluororesin, polyacetal, thermoplastic elastomer, metal oxide, metal, and carbon, but carbon is preferred from the viewpoint of improving heat resistance.

[0021] Examples of the cross-sectional shape of the fibrous catalyst carrier include a round shape, a convex polygonal shape, a star shape, and a porous structure. The fibrous catalyst carrier may have an uneven surface. From the viewpoint of increasing the amount of metal-containing catalyst contained in the fibrous catalyst carrier and enhancing catalytic activity, the fibrous catalyst carrier preferably has a porous structure. From the viewpoint of improving the gas diffusion efficiency inside the catalyst composite and enhancing the reaction rate and heat dissipation efficiency, the catalyst carrier more preferably has a co-continuous porous structure. Here, the co-continuous porous structure refers to a structure in which the skeleton and voids each form a continuous structure. In this specification, the term "co-continuous porous structure" refers to a structure in which, for example, when a sample sufficiently cooled in liquid nitrogen is cut with tweezers or the like and the cross section is observed using a scanning electron microscope (SEM) or the like, a structure in which the skeleton (branch portions) and void portions (pore portions) are each continuous and intertwined is observed.

[0022] When the catalyst composite is composed of a catalyst support and a metal-containing catalyst, the metal-containing catalyst can be appropriately selected depending on the target reaction. Examples of metal-containing catalysts include metals such as ruthenium, nickel, cobalt, rhodium, platinum, and palladium, as well as alloys thereof. The metal-containing catalyst may also be a compound containing a metal element, such as a metal carbide, metal oxide, or metal nitride. When the catalyst support has a fibrous structure, the metal-containing catalyst preferably has a particulate shape. To improve the specific surface area of ​​the metal-containing catalyst and promote gas contact, the particle diameter of the metal-containing catalyst is preferably 10 μm or less, more preferably 1 μm or less. Here, the particle diameter refers to the arithmetic mean value of the particle diameters of 100 metal-containing catalyst particles, and can be measured using a scanning electron microscope. Specifically, the metal-containing catalyst is observed at a magnification of 3,000x using a scanning electron microscope, and the particle diameter of 100 randomly selected metal-containing catalyst particles is measured. Note that if the metal-containing catalyst is not spherical, the particle diameter is the arithmetic mean value of the maximum and minimum diameters of the metal-containing catalyst. The particle size of the metal-containing catalyst can be determined by calculating the number average value thereof. The particle size of the metal-containing catalyst can be appropriately adjusted to a desired range by changing the concentration of the metal raw material liquid, the impregnation time of the catalyst support in the metal raw material liquid, etc. in the manufacturing method of the catalyst composite described later.

[0023] <Gas separation membrane> The reactor of the present invention contains a gas separation membrane, which has a higher permeability to specific components (permeating components) contained in the fluid to be separated than to other components (non-permeating components). When the gas separation membrane is a membrane that selectively permeates at least a portion of the product, selectively discharging a portion of the product from the reaction mixture present inside the reactor can slow the rate of the reverse reaction and shift the reaction equilibrium toward the product. Therefore, it is preferable that the permeating component of the gas separation membrane is at least a portion of the product. When the product contains water, selectively discharging water from the system can slow the rate of the reverse reaction and omit purification of the reaction mixture by distillation. Therefore, when the product contains water, it is more preferable that the permeating component of the gas separation membrane is water.

[0024] The gas separation membrane 3 of the present invention is a fibrous structure. By using a gas separation membrane as a fibrous structure, the gas flow path inside the reactor is oriented along the fiber axis, allowing the gas to flow efficiently inside the reactor. As mentioned above, when an object is a fibrous structure, this means that the length (maximum length) of the longest part of the object (target object) is 100 times or more the diameter of the cross section of the target object if the cross section is circular, or the maximum width of the cross section if the cross section of the target object is other than circular. The gas separation membrane is 、 Gas separation membranes are hollow fibrous structures, which tend to increase gas permeability through the center of the fiber. R (Hereinafter, gas separation membranes that are hollow fibrous structures may be referred to as "hollow fiber membranes").

[0025] Examples of gas separation membranes include inorganic membranes such as zeolite membranes, metal-organic framework (MOF) membranes, and carbon membranes, as well as polymer membranes. When the reactor is used in a severe environment such as a high temperature or an acidic or alkaline environment, inorganic membranes with excellent heat resistance and chemical resistance are preferred, and carbon membranes are more preferred as inorganic membranes.

[0026] Zeolite membranes include membranes made of aluminosilicates such as NaX type (FAU), ZSM-5, MOR, silicalite, and A type. Two or more of these may be used. Zeolite species preferably have a Si / Al ratio similar to that of the zeolite grown secondary by hydrothermal synthesis reaction.

[0027] Examples of MOF membranes include membranes made of Cu-BTC, MOF-5, IRMOF-3, MIL-47, MIL-53, MIL-96, MMOF, SIM-1, ZIF-7, ZIF-8, ZIF-22, ZIF-69, ZIF-90, etc. Two or more of these may be used.

[0028] Examples of carbon films include films obtained by carbonizing polyphenylene oxide, polyvinyl alcohol, polyacrylonitrile, phenolic resin, wholly aromatic polyester, unsaturated polyester resin, alkyd resin, melamine resin, urea resin, polyimide resin, diallyl phthalate resin, lignin resin, urethane resin, etc. Two or more of these may be used.

[0029] Examples of polymer membranes include membranes made of aromatic polyimide, cellulose acetate, polysulfone, aromatic polyamide, polyetherimide, polyethersulfone, polyacrylonitrile, polyphenylene sulfide, polyetheretherketone, polytetrafluoroethylene, polyvinylidene fluoride, poly(1-trimethylsilylpropyne), polydimethylsiloxane, polyvinyltrimethylsilane, poly(4-methylpentene), ethyl cellulose, natural rubber, poly(2,6-dimethylphenylene oxide), low-density polyethylene, high-density polyethylene, styrene, polyethyl methacrylate, polycarbonate, polyester, aliphatic polyamide, polymethyl methacrylate, polyvinyl alcohol, silicone, etc. Two or more of these may be used.

[0030] Nanoparticles can be added to gas separation membranes to improve the permeability of permeating components. Examples of nanoparticles include silica, titania, zeolite, metal oxides, metal-organic frameworks (MOFs), and carbon nanotubes (CNTs).

[0031] In one embodiment of the present invention, the gas separation membrane may have a structure in which a separation layer is disposed on a porous fiber support. The separation layer may be disposed on both surfaces of the porous fiber support, but is preferably disposed on only one surface. Furthermore, since the separation layer comes into direct contact with the gas to be separated, it is preferable that the separation layer has low chemical activity and heat resistance, and specifically, is preferably made of carbon.

[0032] Examples of materials for the porous fiber support include inorganic materials such as alumina, silica, cordierite, zirconia, titania, Vycor glass, zeolite, magnesia, and sintered metal; organic materials containing at least one polymer selected from the group consisting of homopolymers and copolymers of polysulfone, polyethersulfone, polyamide, polyester, cellulose-based polymer, vinyl polymer, polyphenylene sulfide, polyphenylene sulfide sulfone, polyphenylene sulfone, and polyphenylene oxide; and carbon obtained by carbonizing an organic material made of a carbonizable resin. Examples of carbonizable resins include polyphenylene oxide, polyvinyl alcohol, polyacrylonitrile, phenolic resin, wholly aromatic polyester, unsaturated polyester resin, alkyd resin, melamine resin, urea resin, polyimide resin, diallyl phthalate resin, lignin resin, and urethane resin. Two or more of these may be used. In particular, in order to improve the heat resistance of the porous fiber support, it is preferable that the porous fiber support be made of an inorganic material or carbon, and from the viewpoint of reducing the fiber diameter of the support and increasing the area of ​​the gas separation membrane contained in the reactor, it is more preferable that the porous fiber support be made of carbon. In order to improve gas permeability, it is preferable that the porous fiber support have a bicontinuous porous structure. Here, as described above, the bicontinuous porous structure refers to a structure in which the skeleton and voids each form a continuous structure.

[0033] <Gas-phase reaction reactor> The reactor of the present invention contains a catalyst composite and a gas separation membrane independently. Here, "containing the catalyst composite and the gas separation membrane independently" means that the catalyst composite and the gas separation membrane are contained as separate bodies.

[0034] Hereinafter, the reactor is not particularly limited as long as it contains a catalyst composite and a gas separation membrane. One embodiment will be illustrated with reference to the drawings. The reactor has one or more gas inlets 4 and one or more gas outlets 5, and raw material gas 9 is introduced through the gas inlet 4. The raw material gas 9 reacts inside the reactor. Because the catalyst composite 2 has the effect of increasing the rate of the target chemical reaction, the reaction mainly occurs near the catalyst composite 2. To increase the reaction rate, the reactor may be heated. A portion of the reaction mixture resulting from the reaction is discharged through the gas outlet 5, while another portion permeates the gas separation membrane 3 and is discharged through the separated gas outlet 6. A sweep gas 7 may be circulated through the permeated gas flow path 11 to rapidly discharge the gas that permeates the gas separation membrane 3 through the separated gas outlet 6. The type of sweep gas 7 is not particularly limited, but is preferably an inert gas such as helium, nitrogen, or argon from the viewpoint of suppressing side reactions inside the reactor, and among these, nitrogen is more preferable from the viewpoint of reducing the operating cost of the reactor.

[0035] Inside the reactor, the catalyst composite 2 and the gas separation membrane 3 are preferably aligned in one direction. When the catalyst composite 2 and the gas separation membrane 3 are both aligned in one direction, the gas flow path inside the reactor is also aligned in one direction. Therefore, compared to when the catalyst composite 2 and the gas separation membrane 3 are not aligned in one direction, it is possible to prevent gas from stagnating inside the reactor, and to improve the reaction efficiency when the gas flow rate inside the reactor is increased. There are no particular restrictions on the direction in which they are aligned, but it is preferable that the catalyst composite and the gas separation membrane are also aligned in one direction along the longest direction of the reactor.

[0036] Furthermore, in order to improve reaction efficiency by allowing the reactants reacted in the catalyst composite 2 to quickly reach the gas separation membrane 3 and quickly discharge the permeated components outside the system, it is preferable that the catalyst composite 2 and the gas separation membrane 3 are arranged closer to each other inside the reactor. Specifically, for a plurality of catalyst composites, assuming the total number of all catalyst composites to be 100%, when focusing on a particular catalyst composite, the proportion of catalyst composites whose fibrous structures serve as gas separation membranes is preferably 70% or more, and more preferably 80% or more. To explain this further, when focusing on a catalyst composite in the reactor, the fibrous structures closest to it will be either a gas separation membrane or another catalyst composite. In a preferred embodiment of the present invention, the proportion of fibrous structures closest to a catalyst composite that serve as gas separation membranes is increased to 70% or more, thereby improving reaction efficiency.

[0043] Note that, assuming the number of all catalyst composites to be 100%, focusing on a certain catalyst composite, it is preferable that the catalyst composites whose nearest fibrous structure becomes a gas separation membrane are 70% or more, but the upper limit is not particularly limited, and it is most preferably 100%. In other words, it is particularly preferable that the nearest fibrous structure becomes a gas separation membrane in all catalyst composites. Similarly, focusing on a certain catalyst composite, it is preferable that the catalyst composites whose second nearest fibrous structure becomes a gas separation membrane are 60% or more, and more preferably 70% or more, but the upper limit is not particularly limited, and it is most preferably 100%. In other words, it is particularly preferable that the second nearest fibrous structure becomes a gas separation membrane in all catalyst composites. As a method for arranging the catalyst composite 2 and the gas separation membrane 3 closer to each other inside the reactor, a method such as inserting the catalyst composite 2 and the gas separation membrane 3 into the vessel 1 using a guide or the like can be used in the reactor manufacturing method described below, in which the catalyst composite 2 and the gas separation membrane 3 are alternately arranged inside the vessel 1 when they are inserted.

[0037] The chemical processes to which the reactor of the present invention can be applied are not particularly limited, but examples include hydrogen production by steam reforming of methane, hydrogen production from methylcyclohexane, methane synthesis or methanol synthesis from carbon dioxide and hydrogen, and synthesis of synthesis gas (a mixed gas of carbon monoxide and hydrogen) from carbon dioxide and water or carbon dioxide and methane.

[0038] In the membrane reactor of the present invention, the cross-sectional shape of the vessel 1 is preferably elliptical or circular, more preferably circular, from the viewpoint of improving the pressure resistance of the vessel. Here, the cross section of the vessel refers to a cross section of the vessel perpendicular to the longitudinal direction of the fluid separation membrane. Examples of materials for the vessel include metal, resin, fiber-reinforced plastic (FRP), etc., and can be appropriately selected depending on the environment of the installation location and the conditions of use. In applications requiring pressure resistance and heat resistance, metals that combine strength and moldability are preferred, and stainless steel is more preferred.

[0039] <Production method of methane or methanol> The reactor of the present invention can be used to produce various gases by appropriately selecting the catalyst composite and the gas separation membrane to be separated. A preferred embodiment of a method for producing methane or methanol using the reactor of the present invention comprises the following steps:

[0040] Step 1: A step of supplying carbon dioxide and hydrogen to the reactor of the present invention.

[0041] Here, carbon dioxide and hydrogen constitute the raw material gas.

[0042] Generally, methane or methanol can be produced by methods such as refining natural gas or reacting synthetic gas obtained from various fossil fuels. However, a production method using carbon dioxide as a raw material is preferred because carbon dioxide is easily available, highly stable, and easy to handle, and can produce methane, which will be a next-generation clean fuel, or methanol, which can be used to synthesize a variety of chemical products and fuels.

[0043] When carbon dioxide and hydrogen are used as the feed gases, the catalyst composite is not particularly limited as long as it has a fibrous structure, and various catalyst composites can be used. For example, aluminum oxide, titanium oxide, cerium oxide, zeolite, carbon, etc. are preferably used as catalyst supports. Furthermore, nickel, ruthenium, or oxides thereof are preferably used as metal-containing catalysts in the production of methane, and rhenium, silver, copper oxide, zinc oxide, zirconium oxide, etc. are preferably used in the production of methanol.

[0044] In one embodiment of the method for producing methane or methanol according to the present invention, water is produced as a by-product. Therefore, the permeable component of the gas separation membrane disposed in the reactor is preferably methane, methanol, or water. In one embodiment of the method for producing methane or methanol according to the present invention, which includes a step of supplying carbon dioxide and hydrogen to the reactor shown in FIG. 1 , a gas rich in methane or methanol can be obtained from the separated gas outlet 6 when the permeable component of the gas separation membrane is methane or methanol; from the separated gas outlet 6 when the permeable component of the gas separation membrane is water; and from the gas outlet 5 when the permeable component of the gas separation membrane is water.

[0045] In the method for producing methane or methanol according to one embodiment of the present invention, the reaction temperature is preferably 150°C or higher, more preferably 250°C or higher. Furthermore, the reaction temperature is preferably 600°C or lower, more preferably 500°C or lower. Here, the reaction temperature refers to the average temperature of the catalyst composite inside the reactor. When the reaction temperature is 150°C or higher, the chemical reaction rate to produce methane or methanol is sufficiently high, allowing for efficient production of methane or methanol. When the reaction temperature is 200°C or higher, the chemical reaction rate is even higher, allowing for more efficient production of methane or methanol. On the other hand, since the reaction from carbon dioxide and hydrogen to methane or methanol is an exothermic reaction, a lower reaction temperature increases the equilibrium constant of the reaction, favoring the production of methane or methanol. Furthermore, when the catalyst composite is composed of a catalyst support and a metal-containing catalyst, a lower reaction temperature can suppress sintering of the metal-containing catalyst, thereby maintaining the activity of the metal-containing catalyst for a long period of time. Therefore, the reaction temperature is preferably 600°C or lower, more preferably 500°C or lower. To improve the reaction efficiency, the inside of the reactor may be pressurized to a pressure higher than atmospheric pressure.

[0046] <Method for manufacturing reactor, catalytic composite, and gas separation membrane> The reactor of the present invention may be produced by any method, including a method of housing a catalyst composite and a gas separation membrane (hereinafter referred to as production method 1), or a method of producing a reactor housing a gas separation membrane and a catalyst support, and then loading a metal-containing catalyst or its raw materials into the reactor to support the metal-containing catalyst on the catalyst support (hereinafter referred to as production method 2). Production method 1 is more preferred because it allows the catalyst to be reliably supported on the catalyst composite.

[0047] In order to position the catalyst composite and the gas separation membrane closer together inside the reactor, a guide may be used when storing the catalyst composite and the gas separation membrane. A guide refers to a jig for arranging the storage location of the fibrous structures inside the reactor. For example, a plate that can be stored inside the vessel and has a grid-like opening for passing the fibrous structures through can be used as a guide. After storing the guide inside the vessel, the catalyst composite and the gas separation membrane can be inserted into each opening of the guide in an alternating arrangement, thereby positioning the catalyst composite and the gas separation membrane closer together. The guide may be removed after inserting the catalyst composite and the gas separation membrane or after fixing the catalyst composite and the gas separation membrane to the vessel at the potting site.

[0048] The catalyst composite of the present invention can be produced by using various known fibrous structures such as carbon fiber, metal wire, or porous alumina fiber as a fibrous catalyst support and supporting a metal-containing catalyst by techniques such as sputtering or wet impregnation. Supporting a metal-containing catalyst by wet impregnation can be carried out, for example, by impregnating a fibrous catalyst support with a raw material solution in which a metal salt, metal fine particles, or the like is dissolved or dispersed, followed by drying and calcination treatment. When the specific surface area of ​​the catalyst composite is 10 m 2 / g or more, such methods include changing the fiber diameter or cross-sectional shape of the catalyst composite, embedding fine particles inside the fibers and then removing them, and, if the catalyst composite contains carbon fibers, subjecting it to an activation treatment.

[0049] The gas separation membrane of the present invention can be produced, for example, by wet-coating a known porous fiber that functions as a support with a carbonizable resin, followed by carbonization. Examples of wet-coating methods for the carbonizable resin include dissolving the carbonizable resin in a suitable solvent, filling the resulting solution into a nozzle, and passing the porous fiber through the nozzle. [Example]

[0050] EXAMPLES 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.

[0051] [Rating A] Specific surface area The specific surface area of ​​the catalyst composites used in each example and comparative example was measured by the BET flow method (adsorption gas N2) using a fully automatic specific surface area measuring device, Macsorb HM Model-1210 (manufactured by Mountec Co., Ltd.) The catalyst composites were degassed at 100°C for 60 minutes.

[0052] [Evaluation B] Arrangement of catalyst composite and gas separation membrane A reactor in which both the catalyst composite and the gas separation membrane were fibrous structures was cut in a direction perpendicular to the fiber axis. The cut surface was observed with a digital microscope (Keyence VHX-D500). Focusing on a catalyst composite, the number of catalyst composites whose fibrous structures were closest to it and which formed the gas separation membrane was counted, and the percentage (hereinafter referred to as the "first proximity rate") was calculated, assuming the total number of catalyst composites was 100%. Focusing on a catalyst composite, the number of catalyst composites whose fibrous structures were second closest to it and which formed the gas separation membrane was also counted, and the percentage (hereinafter referred to as the "second proximity rate") was calculated.

[0053] [Evaluation C] Reaction efficiency and heat dissipation characteristics of the reactor The catalyst composite of the prepared reactor was suitably activated in hydrogen / nitrogen (volume ratio 1:9). After activation of the catalyst composite, a hydrogen / carbon dioxide feed gas (volume ratio 4:1) was continuously introduced through the gas inlet of the reactor. The total flow rate of the feed gas was 100 sccm / min, the pressure inside the reactor was 20 bar, and the reaction temperature was 300 °C. Nitrogen was circulated as a sweep gas at a rate of 70 sccm / min through the hollow fiber membrane of the reactor. The gas released from the gas outlet (hereinafter referred to as "released gas") was analyzed by GC-TDC, and the reaction efficiency and methane selectivity were calculated using the following equations. In addition, the local temperature at each point in the reactor was measured using a radiation thermometer to evaluate the heat dissipation characteristics, and the maximum local temperature during the reaction was evaluated.

[0054] Reaction efficiency = (molar concentration of carbon dioxide in the feed gas - molar concentration of carbon dioxide in the released gas) / molar concentration of carbon dioxide in the feed gas Methane selectivity = molar concentration of methane in effluent gas / (molar concentration of methane in effluent gas + molar concentration of carbon monoxide in effluent gas) (Production Example 1) As a fibrous structure having a bicontinuous porous structure, porous carbon fibers were prepared by the following method.

[0055] A spinning dope was prepared by mixing 10 parts by weight of polyacrylonitrile (PAN) (MW 150,000) manufactured by Polysciences, 10 parts by weight of polyvinylpyrrolidone (PVP) (MW 40,000) manufactured by Sigma-Aldrich, and 80 parts by weight of dimethyl sulfoxide (DMSO) manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., and stirring the mixture at 100°C.

[0056] 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 95 wt% aqueous DMSO solution from the outer tube.Then, the mixture was introduced into a coagulation bath consisting of pure water at 30°C and then dried at 80°C for 10 minutes in a circulating hot air dryer to produce a hollow fiber-shaped porous carbon fiber precursor.

[0057] The porous carbon fiber precursor was then passed through an electric furnace at 245°C and heated in an air atmosphere for 2 hours to perform an infusible treatment. The infusible fiber was then carbonized at 700°C to produce hollow porous carbon fibers (0.3 mm in diameter) composed primarily of carbon.

[0058] (Production Example 2) A fibrous structure without a porous structure was produced in the same manner as in Production Example 1, except that the composition of the spinning dope was 20 parts by weight of PAN and 80 parts by weight of DMSO.

[0059] (Production Example 3) The porous carbon fiber prepared in Production Example 1 was impregnated with a 10 wt % aqueous solution of nickel (II) nitrate hexahydrate, and then evaporated to dryness. The resulting composite was fired in a nitrogen atmosphere at 500°C for 3 hours to produce catalyst composite A, which used the porous carbon fiber as a catalyst support and nickel oxide as a metal-containing catalyst. The specific surface area of ​​catalyst composite A was 115 m 2 / g.

[0060] (Production Example 4) The fibrous structure produced in Production Example 2 was subjected to the same treatment as in Production Example 3 to produce catalyst composite B. The specific surface area of ​​catalyst composite B was 1.0 m 2 / g.

[0061] (Production Example 5) The porous carbon fiber prepared in Production Example 1 was used as a support, and the spinning dope was used as a coating liquid to coat the surface of the support by a nozzle coating method. After washing with water and drying, a porous fiber having a separation layer precursor disposed thereon was obtained. At this time, the gap between the support and the coating nozzle was 25 μm.

[0062] The resulting precursor was then heated in an oxygen atmosphere at 250°C for 30 minutes for infusibilization, and then heated in a nitrogen atmosphere at 800°C for 20 minutes for carbonization, yielding a hollow fiber gas separation membrane with a separation layer mainly composed of carbon.

[0063] [Example 1] A reactor vessel was prepared by drilling holes of 1 mm in diameter as a gas inlet and gas outlet in the wall of a stainless steel pipe of 10 cm in length, 6 mm in outer diameter, and 1 mm in thickness.

[0064] A guide with a lattice of holes was passed through the reactor vessel, and 20 catalyst composites obtained in Production Example 3 and 20 gas separation membranes obtained in Production Example 5 were inserted so that the catalyst composites and gas separation membranes alternated and were aligned in the same direction as the longest direction of the vessel. The reactor was fabricated by fixing the bundled catalyst to the inner surface of a stainless steel pipe with an epoxy resin adhesive.

[0065] The first proximity rate of this reactor was 100%, the second proximity rate was 85%, the reaction efficiency was 95%, and the methane selectivity was 90%. The maximum temperature was 345°C.

[0066] [Example 2] A reactor was prepared in the same manner as in Example 1, except that no guide was used and the catalyst composite and gas separation membrane were inserted randomly.

[0067] The first proximity ratio of this reactor was 50%, the second proximity ratio was 50%, the reaction efficiency was 95%, and the methane selectivity was 90%. The maximum temperature was 360°C.

[0068] [Comparative Example 1] A reactor was produced in the same manner as in Example 2, except that METH134 (aluminum-supported nickel oxide, non-fibrous), a commercially available product, was used as the catalyst composite in bulk.

[0069] The reaction efficiency of this reactor was 70%, the methane selectivity was 90%, and the maximum temperature was 450°C.

[0070] Comparative Example 2 A reactor was produced in the same manner as in Example 1, except that 20 catalyst composites obtained in Production Example 4 were used as the catalyst composites.

[0071] The reaction efficiency of this reactor was 65%, the methane selectivity was 90%, and the maximum temperature was 405°C. [Explanation of symbols]

[0072] 1: Vessel 2: Catalytic complex 3: Gas separation membrane 4: Gas inlet 5: Gas outlet 6: Separated gas outlet 7: Sweep gas 8: Potting area 9: Raw material gas 10: Non-permeable gas

Claims

1. A reactor for a gas phase reaction that independently contains a catalyst composite and a gas separation membrane, The gas phase reaction reactor is provided with one or more gas inlets, one or more gas outlets, and one or more separated gas outlets, and has a structure in which a raw material gas is introduced through the gas inlet, a portion of the gas is discharged through the gas outlet, and another portion permeates a gas separation membrane and is discharged through the separated gas outlet, The catalyst composite is a fibrous structure having a specific surface area of ​​10 m ２ / g or more, A catalyst comprising a plurality of the catalyst complexes; When the number of all catalyst composites is taken as 100%, and a certain catalyst composite is taken into consideration, the number of catalyst composites whose nearest fibrous structures become gas separation membranes is 70% or more, A reactor for a gas phase reaction, wherein the gas separation membrane has a hollow fiber structure.

2. 2. The reactor for a gas phase reaction according to claim 1, wherein the catalyst composite and the gas separation membrane are arranged in one direction along the longest direction of the reactor.

3. The catalytic composite comprises a catalyst support and a metal-containing catalyst; 3. The reactor for a gas phase reaction according to claim 1, wherein the catalyst support is a fibrous structure made of carbon.

4. 4. The reactor for a gas phase reaction according to claim 3, wherein the catalyst support has a bicontinuous porous structure.

5. The gas separation membrane has a structure in which a separation layer is disposed on a porous hollow fiber support, 5. The reactor for a gas phase reaction according to claim 1, wherein the separation layer is made of carbon.

6. 6. The reactor for a gas phase reaction according to claim 5, wherein the porous hollow fiber support is made of carbon.

7. 7. The reactor for a gas phase reaction according to claim 5 or 6, wherein the porous hollow fiber support has a bicontinuous pore structure.

8. A method for producing methane or methanol using the reactor for gas phase reaction according to any one of claims 1 to 7, comprising the following steps: Step 1: A step of supplying carbon dioxide and hydrogen to the gas phase reaction reactor.

Images