Membrane reactor, chemical plant, and method for manufacturing fluid

Abstract

The present invention addresses the problem of providing a membrane reactor with which a processing amount and a processing speed are achieved simultaneously, the gist of the present invention lying in a membrane reactor including, in a vessel, fluid separating membranes, and a fibrous material present between the fluid separating membranes, wherein the fibrous material supports a catalyst.

Description

Membrane reactor, chemical plant and method for producing fluid

[0001] The present invention relates to a membrane reactor.

[0002] Generally, chemical processes consist of a reaction process and a purification process. A reaction process is a process in which a product is obtained from reactants, and a catalyst is used as needed. In order to increase the yield of a reaction process, it is necessary to improve the reaction rate, but there is an upper limit to the reaction rate governed by chemical equilibrium, and in some cases the reaction rate cannot be increased due to the suppression of side reactions. On the other hand, a purification process is a process in which the product is separated from unreacted materials and by-products after the reaction. Distillation, a typical purification process, requires adjusting the temperature and pressure, which poses the issue of large energy losses.

[0003] Therefore, in chemical processes where purification by membrane separation is possible, a membrane reactor that integrates the reaction process and purification process has been proposed. In a membrane reactor, a catalyst is placed on the surface of or between the separation membranes, and the reaction process proceeds in the space where the separation membranes are present. In parallel, products or by-products generated in the reaction process are removed from the reaction system through the separation membrane, shifting the equilibrium toward the product side and improving the reaction rate. In addition, by using the energy (pressure or heat) generated during the reaction, purification can be performed with less energy. In a membrane reactor, methods of efficiently supplying removed components to the separation membrane include placing spacers or straightening plates in the reaction chamber (see, for example, Patent Document 1 and Patent Document 2).

[0004] JP 2004-34025 A JP 2001-213611 A

[0005] Patent Document 1 discloses a separation module having at least one bundle of ceramic capillaries (9) and a housing surrounding the bundle, the capillaries being connected at their (both) ends by a perforated plate, and the housing having an inlet pipe and / or an outlet pipe connected to the interior of the capillary for a first substance flow and an inlet pipe and / or an outlet pipe connected to the gap between the capillaries for a second substance flow, characterized in that the distance between the capillaries is maintained constant by a spacer (6). However, with the method of Patent Document 1, when the number of ceramic capillaries housed in the housing is increased, the spacer for generating forced flow creates dead space in the separation module, partially covering the surface of the ceramic capillaries or filling up the catalyst storage space. The creation of dead space raises concerns about reduced productivity and an increase in the size of the equipment.

[0006] Patent Document 2 discloses a selectively permeable membrane reactor in which a raw material gas flowing in through an inlet of the reactor reacts in a catalyst-filled reaction chamber, the resulting product gas flows out through the outlet of the reactor, and by-product gas permeates through a selectively permeable membrane and flows out of the reaction chamber. The reactor is equipped with a porous tube having a selectively permeable membrane formed on its surface, a catalyst layer is provided in the gap between the inner wall of the reactor and the porous tube to form a reaction chamber, and a straightening vane is provided in the reaction chamber to guide the by-product gas generated near the inner wall of the reactor toward the surface of the porous tube. However, in the method of Patent Document 2, when multiple porous tubes are installed in the reaction chamber, the distance between the porous tubes must be greater than the width of the straightening vane, making it difficult to increase the packing ratio of the porous tubes and to increase the surface area of ​​the selectively permeable membrane per unit volume of the reaction chamber. Furthermore, when the number of porous tubes is increased, the arrangement of the straightening vanes becomes complicated, making manufacturing difficult.

[0007] In order to solve the above problems, the present invention has the following configuration: That is, the present invention is a membrane reactor including, in a vessel, fluid separation membranes for separating a fluid to be separated and fibrous materials present between the fluid separation membranes, the fibrous materials supporting a catalyst.

[0008] In the membrane reactor of the present invention, the fibrous material supports at least a portion of the catalyst, so that the removed component can be supplied to the fluid separation membrane while minimizing dead space, thereby improving the productivity of the target product.

[0009] Fig. 1 is a schematic diagram showing a cross section including an inlet and outlet for fluids of one embodiment of the membrane reactor of the present invention. Fig. 2 is a schematic diagram showing two compartments of the membrane reactor of Fig. 1. Fig. 3 is a schematic diagram showing one embodiment of the arrangement of the fluid separation membrane and fibrous material of the present invention. Fig. 4 is a schematic diagram showing another embodiment of the arrangement of the fluid separation membrane and fibrous material of the present invention.

[0010] The membrane reactor of the present invention is a membrane reactor comprising, in a vessel, fluid separation membranes for separating a fluid to be separated and fibrous materials present between the fluid separation membranes, and characterized in that the fibrous materials support a catalyst.

[0011] The present invention will be described below by way of examples with reference to the drawings, but the present invention should not be construed as being limited to the examples shown in the drawings.

[0012] FIG. 1 shows a cross-sectional schematic diagram of one embodiment of the membrane reactor of the present invention. FIG. 1 is a cross-sectional schematic diagram including a fluid inlet and outlet of a membrane reactor containing a fluid separation membrane that is a hollow fiber membrane. The fluid referred to here refers to a feed fluid, a fluid to be separated, a permeated fluid, or a non-permeated fluid. The feed fluid is a fluid containing reactants. The fluid to be separated is a mixture of reactants, products, by-products, impurities, sweep gas, etc. The permeated fluid is a fluid that has permeated the fluid separation membrane. The non-permeated fluid is a fluid that is discharged from the membrane reactor without permeating the fluid separation membrane.

[0013] The membrane reactor of FIG. 1 is divided into two compartments by a fluid separation membrane 1, which is a hollow fiber membrane having a hollow portion 2, within a vessel 12. The compartment 1 is the outer compartment of the fluid separation membrane 1, and the compartment 2 is the inner compartment of the fluid separation membrane 1. The two compartments will be explained using FIG. 2. FIG. 2 is a schematic diagram of FIG. 1 with the fibrous material removed. The interior of the membrane reactor is divided into compartment 1 (reference numeral 13), which is the outer compartment of the fluid separation membrane 1, and compartment 2 (reference numeral 14), which is the inner compartment of the fluid separation membrane 1. Compartment 1 has an inlet 8 for a feed fluid and an outlet 9 for a non-permeating fluid, while compartment 2 has an outlet 10 for a permeating fluid that has permeated the fluid separation membrane 1 and an inlet 11 for a sweep gas for sweeping the permeating fluid. The outlet 9 for the non-permeating fluid and the outlet 10 for the permeating fluid are connected to external flow paths (not shown), and the non-permeating fluid and the permeating fluid are recovered.

[0014] Fibrous material 3 is present between the fluid separation membranes 1 in compartment 1, and the fibrous material 3 supports a catalyst 4 (not shown). The fibrous material 3 may be present not only between the fluid separation membranes 1 (for example, between the fluid separation membrane and the vessel), and the catalyst 4 may also be present on the surface of the fluid separation membrane 1 or in the gaps 5 between the fluid separation membranes. In the membrane reactor of Figure 1, the fibrous material 3 wraps around one fluid separation membrane 1 in a spiral shape, and both ends of the fluid separation membranes 1 bundled in parallel are fixed (potted) to each other at potting regions 7 and are also fixed to a vessel 12, with the fluid separation membrane 1 passing through the potting regions 7.

[0015] The chemical processes to which the membrane reactor of the present invention can be applied are not particularly limited, but examples thereof include hydrogen production by steam reforming of methane, hydrogen production from methylcyclohexane, and methane synthesis or methanol synthesis from carbon dioxide and hydrogen.

[0016] In the membrane reactor of the present invention, the cross-sectional shape of the vessel 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, etc. are more preferred.

[0017] The vessel's feed fluid inlet functions to guide the feed fluid into the membrane reactor. The reactants contained in the feed fluid undergo a chemical reaction in the membrane reactor to form products, and the feed fluid becomes the fluid to be separated. When the fluid separation membrane is used in a dead-end filtration system, compartment 1 only needs to have a feed fluid inlet. When used in a cross-flow filtration system, compartment 1 preferably has a feed fluid inlet and a non-permeating fluid outlet. As long as the vessel's mechanical strength is maintained, it may have multiple feed fluid inlets and non-permeating fluid outlets (hereinafter referred to as "outlets and inlets"). In this case, it is preferable to place a fabric such as mesh or felt between the inlet and the fluid separation membrane, as long as it does not interfere with the passage of the fluid, thereby achieving the effects of diffusing the fluid and protecting the fluid separation membrane. On the other hand, compartment 2 only needs to have a permeating fluid outlet, but may also have a sweep gas inlet to actively accompany the permeating fluid.

[0018] In the membrane reactor of the present invention, methods for fixing the fluid separation membrane to the vessel include a method in which the fluid separation membrane is fixed directly to the inner surface of the vessel with a potting material, and a method in which a separation membrane element having multiple fluid separation membranes fixed with a potting material is fixed to the vessel via an adapter or the like (an O-ring, for example) that can ensure liquid-tightness or airtightness. Fixing the membrane to the vessel via an adapter or the like is preferred because it allows the separation membrane element alone to be replaced when the performance of the separation membrane element deteriorates over time.

[0019] The membrane reactor or separation membrane element may have one or more potting portions, but from the viewpoint of sufficiently fixing the positions of the fluid separation membranes and maintaining the effective surface area of ​​the fluid separation membranes, it is preferable to fix the two ends of multiple fluid separation membranes bundled in a substantially linear shape with potting material. Alternatively, the bundled multiple fluid separation membranes may be folded into a U-shape and both ends of the fluid separation membranes may be fixed with potting material at one point, or only one end of the fluid separation membrane may be fixed with potting material and the other end may be sealed with a means other than potting material.

[0020] In one embodiment of the present invention, the separation membrane element may have a casing (hereinafter referred to as "element casing") separate from the vessel. The element casing preferably has an inlet and outlet for fluid. The shape of the element casing is not particularly limited as long as it does not prevent the element casing from being housed in the vessel. Examples of materials for the element casing include metal, resin, fiber-reinforced plastic (FRP), etc., and can be selected appropriately depending on the usage situation. For applications requiring high-temperature operation, metal is preferred because of its high heat resistance. From the viewpoint of high compliance with the cure shrinkage of the potting material, resin is preferred, and polyphenylene sulfide, polytetrafluoroethylene, polyethylene, polypropylene, polyether ether ketone, polyphenylene ether, polyetherimide, polyamideimide, and polysulfone are more preferred because they combine moldability and chemical resistance.

[0021] Potting materials include organic adhesives and inorganic adhesives. For applications requiring high temperature operation, inorganic adhesives are preferred due to their high heat resistance.

[0022] Examples of organic adhesives include thermoplastic resins, thermosetting resins, etc. The organic adhesive may further contain other additives.

[0023] Examples of thermoplastic resins suitable as organic adhesives include polyethylene, polyethersulfone, polystyrene, polyphenylene sulfide, polyarylate, polyester, liquid crystal polyester, polyamide, and polymethyl methacrylate. Examples of thermosetting resins include epoxy resin, unsaturated polyester resin, urethane resin, urea resin, phenolic resin, melamine resin, and silicone resin. Two or more of these may be used. Among these, epoxy resin and urethane resin are preferred from the viewpoint of the balance of moldability, curing time, adhesiveness, hardness, and the like.

[0024] Examples of additives contained in the organic adhesive include fillers, surfactants, silane coupling agents, and rubber components. Examples of fillers include silica, talc, zeolite, calcium hydroxide, and calcium carbonate, which have the effects of suppressing heat generation during curing, improving strength, and increasing viscosity. The surfactant and silane coupling agent also have the effects of improving the handleability of the potting material when mixed and improving the infiltration of the potting material between carbon membranes for fluid separation when injected. The rubber component also has the effect of improving the toughness of the cured and molded potting material. The rubber component may be contained in the form of rubber particles.

[0025] Examples of inorganic adhesives include ceramics and cement. Two or more of these may be used. Furthermore, other additives may be contained.

[0026] The membrane reactor of the present invention is characterized by the presence of fibrous material between fluid separation membranes, and the fibrous material supporting a catalyst. Here, "a state in which the fibrous material supports a catalyst" does not mean a state in which the surface of the fibrous material is simply in contact with catalyst particles or the like and can be easily removed with a brush, but rather a state in which the catalyst is chemically or physically fixed to the surface of the fibrous material. As mentioned above, in conventional technology, membrane reactors that incorporate spacers for efficiently supplying the fluid to be separated to the separation membrane have the problem that the spacers themselves create dead space within the membrane reactor, partially covering the surface of the fluid separation membrane or filling up the catalyst storage space. In the membrane reactor of the present invention, the fibrous material between the fluid separation membranes supports a catalyst, allowing the removed component to be supplied to the fluid separation membrane while minimizing dead space, thereby improving productivity of the target product. Furthermore, since the membrane reactor can achieve both fluid permeability and high fluid separation membrane loading, the equipment can be made more compact.

[0027] A fluid separation membrane is a membrane that has a higher permeability to specific components (permeating components) contained in a fluid to be separated than to other components (non-permeating components). The shape of the fluid separation membrane is not particularly limited, and it may be a flat membrane or a hollow fiber membrane, but it is preferable that the fluid separation membrane is a hollow fiber membrane because this makes it easier to increase the membrane area per unit volume when used as a membrane reactor.

[0028] When the fluid separation membrane is a hollow fiber membrane, the inner diameter of the hollow fiber membrane is preferably 10 μm or more and 2,000 μm or less. By making the inner diameter of the hollow fiber membrane 10 μm or more, fluid permeability can be improved. The inner diameter of the hollow fiber membrane is more preferably 20 μm or more, and even more preferably 50 μm or more. On the other hand, by making the inner diameter of the hollow fiber membrane 2,000 μm or less, the outer diameter of the hollow fiber membrane can be reduced, and therefore the membrane area of ​​the fluid separation membrane per unit volume when used as a membrane reactor can be increased. The inner diameter of the fluid separation membrane is more preferably 1,000 μm or less, and even more preferably 500 μm or less.

[0029] When the inner diameter of a hollow fiber membrane, which is a fluid separation membrane, is 10 μm or more and 2,000 μm or less, portions with a small intermembrane distance are formed, causing the flow of the fluid to be separated to become uneven and the surface utilization efficiency of the fluid separation membrane is likely to decrease. However, in one embodiment of the present invention, the fibrous material ensures the intermembrane distance, making it possible to highly pack the fluid separation membrane while maintaining the membrane utilization efficiency.

[0030] When the hollow fiber membrane includes a support as described below, the inner diameter of the hollow fiber membrane refers to the diameter of the hollow portion of the hollow fiber membrane. When the shape of the hollow portion is not circular, the inner diameter of the hollow fiber membrane is considered to be the diameter of the largest inscribed circle that fits within the hollow portion.

[0031] Examples of fluid separation membranes include inorganic membranes such as zeolite membranes, metal-organic framework (MOF) membranes, and carbon membranes, as well as polymer membranes. When the membrane reactor is operated under severe reaction conditions such as high temperature or acidic / basic conditions, inorganic membranes with excellent heat resistance and chemical resistance are preferred, and the inorganic membrane is more preferably a zeolite membrane or a carbon membrane.

[0032] 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 secondarily by hydrothermal synthesis reaction.

[0033] 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, and ZIF-90. Two or more of these may be used.

[0034] 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.

[0035] 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.

[0036] Nanoparticles or the like can be added to the fluid separation membrane to improve the permeability of the permeating component. Examples of nanoparticles include silica, titania, zeolite, metal oxides, metal organic frameworks (MOFs), and carbon nanotubes (CNTs).

[0037] In one embodiment of the present invention, the fluid separation membrane may include a support. When the fluid separation membrane of the present invention includes a support, it is more preferable that the support is disposed on only one surface of the fluid separation membrane.

[0038] Examples of the support include porous inorganic materials such as alumina, silica, cordierite, zirconia, titania, Vycor glass, zeolite, magnesia, and sintered metal; porous 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 porous carbon materials obtained by carbonizing porous organic materials made of carbonizable resins. 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.

[0039] In the membrane reactor of the present invention, the bending radius of the fluid separation membrane is preferably 0.1 cm or more and 100 cm or less. A bending radius of 100 cm or less can prevent the fluid separation membrane from breaking during the fabrication or operation of the membrane reactor. The bending radius is more preferably 10 cm or less, and even more preferably 1 cm or less. There is no particular restriction on the lower limit of the bending radius of the fluid separation membrane, but a bending radius of 0.1 cm or more can impart self-supporting properties to the fluid separation membrane, so it is preferably 0.1 cm or more.

[0040] In one embodiment of the present invention, a fluid separation membrane having a bending radius of 100 cm or less is preferred because it can be wrapped around a rigid fibrous material or can be made to conform to the complex shape of a vessel or fibrous material, thereby improving the degree of freedom in designing a membrane reactor.

[0041] The bending radius of a fluid separation membrane can be determined by sampling a fluid separation membrane 10 cm or more from a membrane reactor, wrapping the sampled fluid separation membrane around a cylinder by 360° or more along the normal direction of the cylinder, and determining the radius of the cylinder at which the fluid separation membrane does not break. If the bending radius of the fluid separation membrane is 1.5 cm or more, evaluation is performed by appropriately reducing the angle at which the sampled fluid separation membrane is wrapped around the cylinder along the normal direction of the cylinder, and the radius of the cylinder at which the fluid separation membrane does not break can be considered to be the bending radius of the fluid separation membrane.

[0042] When the fluid separation membrane supports a catalyst, the bending radius of the fluid separation membrane supporting the catalyst is regarded as the bending radius of the fluid separation membrane.

[0043] In one embodiment of the present invention, the water permeability of the fluid separation membrane is 100 μL / (hr·m ２ · Pa) or less. ２ A fluid separation membrane having a water permeability of 10 μL / (hr·m) or less can be suitably used as a membrane reactor requiring gas separation because the pore size of the separation functional layer is small. ２ ·Pa) or less is more preferable, and 1 μL / (hr·m ２ Pa) or less is more preferable.

[0044] The water permeability of a fluid separation membrane can be calculated from the amount of permeated water recovered from the permeated fluid outlet of the membrane reactor when pure water is supplied from the feed fluid inlet of the membrane reactor, using the following (Equation 1).

[0045] Water permeability (μL / (hr・m ２ Pa)) = Q ｗ / (P×T×A) (Equation 1) [In Equation 1, Qw represents the amount of permeated water (μL), P represents the pressure of the feed water (Pa), T represents the permeation time (hr), and A represents the membrane area of ​​the fluid separation membrane (m ２ ) represents the same.] The fibrous material is present between the fluid molecular membranes of the compartment 1, and serves to ensure the distance between the fluid separation membranes and to guide the fluid to be separated to the fluid separation membrane. Examples of the fibrous material include fibers, nonwoven fabrics, woven fabrics, and knitted fabrics. Two or more of these may be combined.

[0046] Fiber refers to a form in which the length is 100 times or more the diameter, and examples thereof include organic fibers and inorganic fibers. Examples of organic fibers include synthetic fibers, semi-synthetic fibers, and recycled fibers, while examples of inorganic fibers include metal fibers, carbon fibers, glass fibers, and rock fibers. Inorganic fibers are preferably used because of their high heat resistance. Furthermore, nonwoven fabrics, woven fabrics, and knitted fabrics refer to forms in which fibers are processed into a flat surface.

[0047] When the fluid separation membrane is a hollow fiber membrane, the fibrous material is preferably a fiber, since it is easy to arrange it between the fluid separation membranes, and when the fluid separation membrane is a flat membrane, the fibrous material is preferably a nonwoven fabric, a woven fabric, or a knitted fabric. Furthermore, when the fluid separation membrane is a hollow fiber, the fibrous material may wrap around one or more fluid separation membranes in a spiral shape, or may be arranged parallel to the fluid separation membranes. From the viewpoint of being able to arrange the spacers uniformly around the fluid separation membranes, an embodiment in which the spacers wrap around one or more fluid separation membranes in a spiral shape is preferred, and from the viewpoint of workability, an embodiment in which the spacers are arranged parallel to the fluid separation membranes is preferred.

[0048] The length of the fibers is preferably 0.1 to 2.0 times the length of the fluid separation membranes. When the length of the fibers is 0.1 times or more the length of the fluid separation membranes, it becomes easier to ensure the distance between the fluid separation membranes. The length of the fibers is preferably 0.5 times or more the length of the fluid separation membranes, and more preferably 0.75 times or more. On the other hand, when the length of the fibers is 2.0 times or less the length of the fluid separation membranes, the volume occupied by the fibers in the membrane reactor can be reduced and the membrane filling rate can be improved. The length of the fibers is more preferably 1.5 times or less the length of the fluid separation membranes, and even more preferably 1.1 times or less. In addition, when the length of the fibers or fluid separation membranes is discussed in the present invention, it refers to the fibers or fluid separation membranes present in compartment 1, and does not include the potting region or the fibers or fluid separation membranes that penetrate the potting region and are present in compartment 2.

[0049] Figures 3 and 4 show schematic diagrams of an embodiment in which a fluid separation membrane is spirally coated with fibrous materials. Figure 3 is a schematic diagram of an embodiment in which one fluid separation membrane 1 is spirally coated with one fibrous material 3 at an interval of pitch 12, and Figure 4 is a schematic diagram of an embodiment in which two fluid separation membranes 1 are spirally coated with two fibrous materials 3 at an interval of pitch 12. In Figures 3 and 4, the fibrous material 3 supports a catalyst 4 (not shown).

[0050] The covering with the fibrous material may be a single covering in which the fibrous material is wrapped around the fluid separation membrane in a single layer, or a double covering in which the fibrous material is wrapped around the fluid separation membrane in two layers. Alternatively, a multi-stage covering in which the fibrous material is further spirally wrapped around multiple fluid separation membranes wrapped around the fibrous material may be used. Examples of fibrous materials include polyester, nylon, polyolefin, fluororesin, polyacetal, thermoplastic elastomer, metal oxide, and metal. Two or more of these materials may be used.

[0051] Furthermore, when the fibrous material is a fiber, the fibrous material may be a monofilament or a multifilament, but a multifilament is preferred because it is flexible, easy to handle, and has a large surface area for supporting a catalyst. Furthermore, it is more preferable to use a false twisted yarn because it is bulky and makes it easier to ensure the distance between the fluid separation membranes.

[0052] Catalysts increase the reaction rate of chemical processes in membrane reactors by lowering the activation energy of the reaction.

[0053] The membrane reactor of the present invention is characterized in that a catalyst is supported on a fibrous material. The catalyst may be coated on the surface of the fibrous material or attached to the surface of the fibrous material, but it is more preferable that the catalyst be supported on all outer surfaces of the fibrous material because this increases the contact surface area with the reactants. All outer surfaces of the fibrous material include the inner surfaces of the pores when the fibrous material is porous, and the outer surfaces of all single fibers when the fibrous material is multifilament.

[0054] The catalyst support amount of the fibrous material of the present invention is preferably 0.01% by mass or more and 10% by mass or less, relative to 100% by mass of the fibrous material containing the catalyst. When the catalyst support amount of the fibrous material is 0.01% by mass or more, the fibrous material is more likely to exhibit catalytic function for a long period of time. The catalyst support amount of the fibrous material is more preferably 0.1% by mass or more, and even more preferably 1% by mass or more. There is no particular upper limit to the catalyst support amount of the fibrous material, but it is preferably 10% by mass or less, as this allows for effective use of the surface area of ​​the fibrous material.

[0055] The amount of catalyst carried on the fibrous material is expressed as the ratio of the weight of the catalyst carried on the fibrous material to the weight of the fibrous material containing the catalyst, and can be calculated from the weights of the fibrous material before and after carrying the catalyst. The weight of the catalyst carried on the fibrous material can also be estimated by completely eluting the catalyst from the fibrous material and measuring the resulting eluate by inductively coupled plasma mass spectrometry (ICP-MS).

[0056] Methods for supporting a catalyst on a fibrous material include wet plating and dry plating. Wet plating includes, for example, electrolytic plating and electroless plating, and dry plating includes, for example, vapor deposition and sputtering.

[0057] In the membrane reactor of the present invention, the catalyst not supported on the fibrous material may be disposed on the surface of the fluid separation membrane or between the fluid separation membranes. From the viewpoint of not impeding the passage of the fluid, it is preferable that it be disposed on the surface of the fluid separation membrane, and from the viewpoint of increasing the contact surface area of ​​the catalyst, it is preferable that it be disposed between the fluid separation membranes. The catalyst may be disposed both on the surface of the fluid separation membrane and between the fluid separation membranes.

[0058] The type of catalyst is not particularly limited and is appropriately selected depending on the reaction occurring in the membrane reactor.

[0059] The membrane reactor of the present invention preferably has an electric circuit, and the electric circuit is preferably arranged so that an electric current can be passed through the fibrous material, and this embodiment will be described below. The method for passing an electric current through the fibrous material is not particularly limited, and an individual electric circuit may be provided for each fibrous material, or multiple fibrous materials may be incorporated into one electric circuit. From the viewpoint of simplifying the wiring, it is preferable to incorporate multiple fibrous materials into one electric circuit, and in this case, the fibrous materials are arranged so as to be in contact with a current collector, and the current collector is connected to a power source. The fibrous material and the current collector, and the current collector and the power source may be directly connected, or may be connected via a conductor such as a lead wire.

[0060] In one embodiment of the present invention, the electrical resistivity of the fibrous material is preferably 0.1 μΩ·m or more and 1000 μΩ·m or less. When the electrical resistivity of the fibrous material is 0.1 μΩ·m or more, resistance heating occurs when an electric current is passed through the fibrous material, allowing the fibrous material to be used as a heating element, and even if the reaction in the membrane reactor is an endothermic reaction, the inside of the membrane reactor can be directly heated. In resistance heating, all of the power consumed by the resistance is converted into heat, allowing the inside of the membrane reactor to be heated efficiently. The electrical resistivity of the fibrous material is more preferably 0.5 μΩ·m or more, and even more preferably 1 μΩ·m or more. When the electrical resistivity of the fibrous material is 1000 μΩ·m or less, resistance heating can be generated even when the fibrous material is thin, thereby reducing the volume of the fibrous material in the membrane reactor. The electrical resistivity of the fibrous material is more preferably 100 μΩ·m or less, and even more preferably 10 μΩ·m or less.

[0061] Examples of fibrous materials having an electrical resistivity of 0.1 μΩ·m or more and 1000 μΩ·m or less include iron, chromium, aluminum, nickel, platinum, molybdenum, tantalum, tungsten, alloys of these metals, and carbon.

[0062] In one embodiment of the present invention, the fibrous material preferably has an insulating layer on its surface, which inhibits corrosion of the fibrous material when used as a heating element, allowing the fibrous material to be used as a heating element for a long period of time.

[0063] The membrane reactor of the present invention preferably has a heat source or a cooling source, and the fibrous material is preferably arranged so as to be in contact with the heat source or the cooling source, and this embodiment will be described below. The method for heating or cooling the fibrous material, i.e., the heating method or the cooling method for the heat source or the cooling source arranged so as to be in contact with the fibrous material, is not particularly limited, and the fibrous material may be connected directly to the heat source or the cooling source, or may be connected via a heat conductor. From the viewpoint of simplifying the wiring, it is preferable to connect multiple fibrous materials to a heat conductor and then connect them to the heat source or the cooling source, and in this case, the fibrous material is arranged so as to be in contact with the heat conductor, and the heat conductor is connected to the heat source or the cooling source.

[0064] In one embodiment of the present invention, the thermal conductivity of the fibrous material is preferably 1 W / (m K) or more and 1000 W / (m K) or less. When the thermal conductivity of the fibrous material is 1 W / (m K) or more, the inside of the membrane reactor can be heated or cooled by heating or cooling the fibrous material, making it easier to control the temperature inside the membrane reactor even if the reaction inside the membrane reactor is an endothermic reaction or an exothermic reaction. The thermal conductivity of the fibrous material is more preferably 10 W / (m K) or more, and even more preferably 100 W / (m K) or more.

[0065] Examples of fibrous materials with a thermal conductivity of 1 W / (m·K) or more and 1000 W / (m·K) or less include silver, copper, iron, chromium, aluminum, nickel, platinum, molybdenum, tantalum, tungsten, and alloys thereof.

[0066] In other words, from the viewpoint of ease of adjustment when controlling the electrical resistivity to 0.1 μΩ·m or more and 1000 μΩ·m or less, and controlling the thermal conductivity to 1 W / (m·K) or more and 1000 W / (m·K) or less, it is preferable that the fibrous material contains at least one selected from the group consisting of iron, chromium, aluminum, nickel, platinum, molybdenum, tantalum, tungsten, alloys thereof, and carbon.

[0067] The method for producing the membrane reactor of the present invention is not particularly limited, and may be a production method in which a fibrous material pre-supported with a catalyst and a fluid separation membrane are housed (hereinafter referred to as production method 1), or a production method in which a membrane reactor housing a fluid separation membrane and a fibrous material is produced, and then a catalyst is introduced into the membrane reactor to fill the space between the fluid separation membranes and simultaneously support the catalyst on the fibrous material (hereinafter referred to as production method 2). Production method 1 is more preferred because it allows the catalyst to be reliably supported on the fibrous material.

[0068] The chemical processes to which the membrane reactor of the present invention can be applied are not particularly limited, but examples thereof include hydrogen production by steam reforming of methane, hydrogen production from methylcyclohexane, and methane synthesis or methanol synthesis from carbon dioxide and hydrogen.

[0069] The chemical plant of the present invention (hereinafter, sometimes simply referred to as "plant") is a plant including the membrane reactor of the present invention. The plant preferably includes, in addition to the membrane reactor, a pretreatment facility, a purified fluid recovery facility, a by-product fluid recovery facility, etc. The pretreatment facility is a facility for adjusting the composition of the reaction fluid to be supplied to the membrane reactor. The purified fluid recovery facility is a facility for recovering the purified fluid that has permeated the fluid separation membrane, and further purifying it as necessary or supplying it to a pipeline or the like. The by-product fluid recovery facility is a facility for recovering unreacted reaction fluid and by-product fluid, and reusing the unreacted reaction fluid or discharging the by-product fluid after detoxifying it. In the plant of the present invention, it is preferable that the membrane reactor, the pretreatment facility, the purified fluid recovery facility, and the by-product fluid recovery facility are connected by piping or the like, and a purified fluid is continuously produced from the reaction fluid.

[0070] The plant preferably includes a plurality of membrane reactors depending on the processing amount of the fluid to be separated. The plurality of membrane reactors may be connected in series or in parallel with respect to the reaction fluid. From the viewpoint of the production efficiency of the membrane reactor, it is preferable that the membrane reactors are connected in series, and from the viewpoint of being able to partially replace the membrane reactors, it is preferable that the membrane reactors are connected in parallel. One preferred embodiment of the plant of the present invention is an embodiment in which the membrane reactors are connected in series, and the membrane reactors connected in series are further connected in parallel. In this way, it is possible to achieve both the advantages of connecting membrane reactors in series and the advantages of connecting them in parallel.

[0071] There are no particular limitations on the chemical processes to which the plant of the present invention can be applied. Examples include hydrogen production by steam reforming of methane, hydrogen production from methylcyclohexane, and methane synthesis or methanol synthesis from carbon dioxide and hydrogen.

[0072] The method for producing a fluid of the present invention is a method for producing a fluid using the membrane reactor of the present invention, and includes at least the following steps.

[0073] Step 1 involves producing a product from a reactant in a feed fluid using a catalyst present in a membrane reactor, and step 2 involves concentrating the product from the fluid to be separated resulting from step 1 using a fluid separation membrane present in the membrane reactor.

[0074] The products produced from the reaction may contain by-products in addition to the target product, but the product produced in step 1 and the product concentrated in step 2 are both the target product.

[0075] Furthermore, other purification steps or additional steps may be included before or after the above steps 1 and 2. Examples of other purification steps include distillation, adsorption, absorption, etc. Examples of additional steps include component adjustment by mixing with another fluid, etc.

[0076] According to the method for producing a fluid of the present invention, continuous production from a small scale is possible using a membrane reactor.

[0077] 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.

[0078] (Bending Radius of Fluid Separation Membrane) Five fluid separation membranes of 10 cm or more were cut out from the prepared membrane reactor, and the radius of a cylinder at which the fluid separation membrane did not break when the cut-out fluid separation membrane was wrapped around the cylinder by 360° or more along the normal direction was determined. The average value of the obtained radius of the cylinder, expressed to one significant digit, was taken as the bending radius of the fluid separation membrane.

[0079] (Inner diameter of fluid separation membrane) Five fluid separation membranes of 10 cm or more were cut out from the prepared membrane reactor and cut in a direction perpendicular to the fiber axis direction. The cut surfaces were observed with a digital microscope (Keyence VHX-D500), and the diameter of the largest inscribed circle that could fit within the hollow portion was measured. The average value of the diameters of the obtained inscribed circles, expressed to one significant digit, was taken as the inner diameter of the fluid separation membrane.

[0080] (Ratio of fiber length to fluid separation membrane length) Five fibers were sampled from compartment 1 of the membrane reactor in the examples, and their lengths were measured while they were straightened without any stretching force, and the average value was calculated to determine the fiber length. Here, when one or both ends of the fiber were present in the potting region, the fiber was cut at the surface of the potting region in compartment 1 for sampling. The length of the fluid separation membrane was the length between the surface of the potting region at one end of the membrane reactor facing compartment 1 and the surface of the potting region at the other end of the membrane reactor facing compartment 1. The ratio of the fiber length to the fluid separation membrane length was expressed as "fiber length / fluid separation membrane length" with two significant digits.

[0081] (Electrical resistivity of fibrous material) The electrical resistivity of the fibrous material was measured by a four-terminal method. The electrical resistivity was measured by measuring the potential difference between two points on the surface while passing electricity through the fibrous material, and the resistivity β was calculated using the following formula 1. A DC power supply (PAD55-20L manufactured by Kikusui Electronics), a voltmeter (3878A multimeter manufactured by Hewlett-Packard), and an ammeter (DT4252 manufactured by Hioki E.E.). The measurement was performed three times, and the average value expressed with two significant digits was used as the electrical resistivity (μΩ m) of the fibrous material.

[0082] β = ΔU S / (I d) Equation 1 [In the equation, ΔU represents the measured potential difference, I represents the current flowing through the fibrous material, S represents the cross-sectional area of ​​the fibrous material, and d represents the distance between the two electrodes measuring the potential.] (Thermal Conductivity of Fibrous Material) The thermal conductivity of the fibrous material was measured by the laser flash method. To measure the thermal conductivity, the bundled fibrous material was molded into a block shape, and the thermal conductivity was measured using a thermal conductivity measuring device (TC-7000H manufactured by Avantec Riko Co., Ltd.). The measurement was performed three times, and the average value expressed with two significant digits was taken as the thermal conductivity (W / (m K)) of the fibrous material.

[0083] (Amount of catalyst supported on fibrous material) For the fibrous materials of Production Examples 3 to 5, the ratio of the mass of catalyst to the mass of the fibrous material after catalyst support ((mass of fibrous material after catalyst support - mass of fibrous material before catalyst support) / mass of fibrous material after catalyst support) was calculated from the masses of the fibrous material before and after catalyst support. The obtained value was expressed as a percentage with one significant digit and was defined as the amount of catalyst supported on the fibrous material.

[0084] (Product Production Amount) Methylcyclohexane was supplied to the inlet of the supplied fluid of the prepared membrane reactor. Methylcyclohexane was decomposed into toluene and hydrogen using palladium as a catalyst in the membrane reactor, and the hydrogen selectively permeated the fluid separation membrane. Hydrogen was recovered from the outlet of the permeated fluid of the membrane reactor, and the production amount of hydrogen as the product was evaluated from the flow rate measured with a soap film flowmeter and the hydrogen composition ratio obtained by gas chromatography analysis. For the membrane reactors of Examples 2 and 3, the hydrogen production amount was also evaluated when an electric current was passed through the fibrous material and when the fibrous material was heated. Measurements were performed three times, and the average value was rounded to one decimal place to determine the product production amount.

[0085] (Production Example 1) 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. were mixed and stirred at 100°C to prepare a spinning dope.

[0086] The obtained spinning dope was cooled to 25° C., and then a concentric triple spinneret was used to simultaneously discharge an 80 wt % aqueous solution of DMSO from the inner tube, the spinning dope from the middle tube, and a 90 wt % aqueous solution of DMSO from the outer tube, and then the spinning dope was introduced into a coagulation bath of pure water at 25° C. and taken up on a roller to obtain a raw fiber. The obtained raw fiber was washed with water and then dried at 25° C. for 24 hours using a circulating dryer to produce a precursor of a hollow fiber-shaped porous carbon membrane.

[0087] The obtained porous carbon membrane precursor was passed through an electric furnace at 250°C and heated in an air atmosphere for 1 hour to perform an infusibilization treatment, thereby obtaining an infusibilized yarn. Subsequently, the infusibilized yarn was carbonized at a carbonization temperature of 650°C to obtain a fluid separation membrane of Production Example 1, which was an inorganic membrane (carbon membrane) having an outer diameter of 300 µm, an inner diameter of 100 µm, and a bending radius of 5 mm.

[0088] (Preparation Example 2) The fluid separation membrane of Preparation Example 1 was cut into 10 cm pieces, and then palladium as a catalyst was sputtered onto the cut pieces to obtain a palladium-supported fluid separation membrane of Preparation Example 2.

[0089] (Production Example 3) A 170 dtex polyester processed yarn, which is a fibrous material having an electrical resistivity of 1.0 MΩ·m or more and a thermal conductivity of 0.25 W / (m·K), was sputtered with palladium as a catalyst to obtain a catalyst-supported fibrous material of Production Example 3. As a result of evaluation using the above-mentioned method, the catalyst support amount of the fibrous material of Production Example 3 was found to be 3 mass%.

[0090] (Production Example 4) Palladium, a catalyst, was sputtered onto a φ0.2 mm nichrome wire, which was a fibrous material having an electrical resistivity of 1.0 μΩ m and a thermal conductivity of 17 W / (m K), to obtain a catalyst-supported fibrous material of Production Example 4. As a result of evaluation using the above-mentioned method, the catalyst support amount of the fibrous material of Production Example 4 was 0.02 mass%.

[0091] (Production Example 5) Palladium, a catalyst, was sputtered onto a φ0.2 mm SUS wire, which was a fibrous material having an electrical resistivity of 0.74 μΩ m and a thermal conductivity of 16 W / (m K), to obtain a catalyst-supported fibrous material of Production Example 5. As a result of evaluation using the above-mentioned method, the catalyst support amount of the fibrous material of Production Example 5 was 0.02 mass %.

[0092] Example 1: One fluid separation membrane from Production Example 2 was used as a core thread, and the catalyst-supported fibrous material from Production Example 3 was wound in the Z direction at a pitch of 10 mm. Ten fluid separation membranes from Production Example 2 wrapped with the catalyst-supported fibrous material were bundled and housed in an acrylic pipe (inner diameter 3 mm) with a fluid inlet and outlet, and each end of the acrylic pipe was statically potted with epoxy resin. After the epoxy resin cured, the potted portion at one end was cut with a rotary saw to open the fluid separation membrane, thereby obtaining the membrane reactor of Example 1. Evaluation using the above-mentioned method revealed that the bending radius of the fluid separation membrane was 5 mm, the inner diameter of the fluid separation membrane was 100 μm, the ratio of the fiber length to the length of the fluid separation membrane was 1.0, and the product production rate was 33 mL / min.

[0093] Example 2 One fluid separation membrane from Production Example 2 was used as a core thread, and the catalyst-supported fibrous material from Production Example 4 was wound in the Z direction at a pitch of 10 mm. Ten fluid separation membranes from Production Example 2 wrapped with the catalyst-supported fibrous material were bundled and housed in an acrylic pipe (inner diameter 3 mm) with a fluid inlet and outlet, and each end of the acrylic pipe was statically potted using epoxy resin. After the epoxy resin hardened, the potted area at one end was cut with a rotary saw to open the fluid separation membrane. Metal perforated plates were placed on the fluid separation membrane opening surfaces at both ends of the element, and a lead wire and a DC power supply were placed between the two perforated plates to obtain the membrane reactor of Example 2.

[0094] The membrane reactor of Example 2 had an electric circuit. Evaluation results using the above-described method revealed that the bending radius of the fluid separation membrane was 5 mm, the inner diameter of the fluid separation membrane was 100 μm, the ratio of the fiber length to the fluid separation membrane length was 1.0, and the product production rate was 17 mL / min. Furthermore, when an electric current was applied to the fibrous material, the product production rate was 41 mL / min.

[0095] Example 3 One fluid separation membrane from Production Example 2 was used as a core thread, and the catalyst-supported fibrous material from Production Example 4 was wound in the Z direction at a pitch of 10 mm. Ten fluid separation membranes from Production Example 2 wrapped with the catalyst-supported fibrous material were bundled and housed in an acrylic pipe (inner diameter 3 mm) with a fluid inlet and outlet, and one end of the acrylic pipe was statically potted with epoxy resin. After the epoxy resin hardened, the potted area at one end was cut with a rotary saw to open the fluid separation membrane. Metal perforated plates were placed on the fluid separation membrane opening surfaces at both ends of the element, and the two perforated plates were each connected to a heat source, yielding the membrane reactor of Example 3.

[0096] The membrane reactor of Example 3 had a heat source. Evaluation results using the above-described method revealed that the bending radius of the fluid separation membrane was 5 mm, the inner diameter of the fluid separation membrane was 100 μm, the ratio of the fiber length to the fluid separation membrane length was 1.0, and the product production rate was 17 mL / min. Furthermore, when the fibrous material was heated, the product production rate was 36 mL / min.

[0097] Example 4 The membrane reactor of Example 4 was obtained in the same manner as in Example 2, except that the fibrous material carrying the catalyst of Production Example 5 was used instead of the fibrous material carrying the catalyst of Production Example 4. The membrane reactor of Example 4 has an electric circuit. As a result of evaluation using the above-mentioned method, the bending radius of the fluid separation membrane was 5 mm, the inner diameter of the fluid separation membrane was 100 μm, the ratio of the fiber length to the length of the fluid separation membrane was 1.0, and the product production rate was 16 mL / min. Furthermore, when an electric current was applied to the fibrous material, the product production rate was 23 mL / min.

[0098] Example 5 The membrane reactor of Example 5 was obtained in the same manner as in Example 3, except that the fibrous material carrying the catalyst of Production Example 5 was used instead of the fibrous material carrying the catalyst of Production Example 4. The membrane reactor of Example 5 had a heat source. As a result of evaluation using the above-mentioned method, the bending radius of the fluid separation membrane was 5 mm, the inner diameter of the fluid separation membrane was 100 μm, the ratio of the fiber length to the length of the fluid separation membrane was 1.0, and the product production rate was 16 mL / min. Furthermore, when the fibrous material was heated, the product production rate was 34 mL / min.

[0099] Example 6 Ten fluid separation membranes from Production Example 2 and ten catalyst-supported fibrous materials from Production Example 5 were bundled together, with the fluid separation membranes arranged as close together as possible, and then housed in an acrylic pipe (inner diameter 3 mm) with a fluid inlet and outlet, and one end of the acrylic pipe was statically potted with epoxy resin. After the epoxy resin hardened, the potted portion at one end was cut with a rotary saw to open the fluid separation membrane, thereby obtaining the membrane reactor of Example 6.

[0100] As a result of evaluation using the above-mentioned method, the bending radius of the fluid separation membrane was 5 mm, the inner diameter of the fluid separation membrane was 100 μm, the ratio of the fiber length to the fluid separation membrane length was 1.0, and the amount of product produced was 15 mL / min.

[0101] (Comparative Example 1) A membrane reactor of Comparative Example 1 was obtained in the same manner as in Example 1, except that a 170 dtex polyester textured yarn was used instead of the catalyst-supported fibrous material of Production Example 3. As a result of evaluation by the above-mentioned method, the amount of product produced was 11 mL / min.

[0102] 1: Fluid separation membrane 2: Hollow portion 3: Fibrous material 4: Catalyst 5: Gap between fluid separation membranes 7: Potting portion 8: Inlet for feed fluid 9: Outlet for non-permeating fluid 10: Outlet for permeating fluid 11: Inlet for sweep gas 12: Vessel 13: Compartment 1 14: Compartment 2

Claims

1. A membrane reactor comprising a vessel containing fluid separation membranes and fibrous material present between the fluid separation membranes, the fluid separation membranes being hollow fiber membranes, the fibrous material being fibers, and the fibers being spirally wrapped around one or more of the fluid separation membranes; The membrane reactor, wherein the fibrous material supports a catalyst.

2. 2. The membrane reactor of claim 1, wherein the fibers are arranged parallel to the fluid separation membrane.

3. 3. The membrane reactor according to claim 1, wherein the length of the fibers is 0.1 to 2.0 times the length of the fluid separation membrane.

4. The membrane reactor according to any one of claims 1 to 3, wherein the inner diameter of the fluid separation membrane is 10 µm or more and 2,000 µm or less.

5. 5. The membrane reactor according to claim 1, wherein the bending radius of the fluid separation membrane is 0.1 cm or more and 100 cm or less.

6. 6. The membrane reactor according to claim 1, wherein the fibrous material supports 0.01% by mass to 10% by mass of the catalyst relative to 100% by mass of the fibrous material containing the catalyst.

7. The membrane reactor further comprises an electrical circuit, The membrane reactor according to any one of claims 1 to 6, wherein the electric circuit is arranged so that an electric current can be applied to the fibrous material.

8. The membrane reactor according to claim 7 , wherein the electrical resistivity of the fibrous material is 0.1 μΩ·m or more and 1000 μΩ·m or less.

9. The membrane reactor further comprises a heat source or a cooling source; The membrane reactor according to any one of claims 1 to 6, wherein the fibrous material and the heat source or the cooling source are arranged so as to be in contact with each other.

10. The membrane reactor according to claim 9, wherein the thermal conductivity of the fibrous material is 1 W / (m·K) or more and 1000 W / (m·K) or less.

11. The membrane reactor according to any one of claims 1 to 10, wherein the fibrous material contains at least one selected from the group consisting of iron, chromium, aluminum, nickel, platinum, molybdenum, tantalum, tungsten, alloys thereof, and carbon.

12. A chemical plant comprising the membrane reactor according to any one of claims 1 to 11.

13. A method for producing a fluid using the membrane reactor according to any one of claims 1 to 11, comprising at least the following steps:

1. producing a product from a reactant in a feed stream by a catalyst present in a membrane reactor; and concentrating said product by a fluid separation membrane present in a membrane reactor.