Membrane reactor and method for operating the membrane reactor

Abstract

This membrane reactor (4) comprises a separation membrane complex (1) and a catalyst (41). The separation membrane complex (1) comprises a separation membrane (12) and a porous support (11). The catalyst (41) promotes a chemical reaction of raw materials. The support (11) is of a columnar shape that extends in the longitudinal direction. The support (11) has formed therein film-formation cells (i.e., first cells (111a)) that opens at both longitudinal ends. The separation membrane (12) is disposed on the inner surface of the first cell (111a). The catalyst (41) is disposed within the first cell (111a) of the separation membrane complex 1. The ratio of the average particle diameter of the catalyst (41) to the inner diameter of the fist cell (111a) is not less than 0.75 but less than 1. Accordingly, as mentioned above, it is possible to minimize breakage of the separation membrane (12) due to the difference in thermal expansion rate or the like between the catalyst (41) and the separation membrane complex (1).

Description

[Technical Field]

[0001] The present invention relates to a membrane reactor and a method for operating a membrane reactor including the membrane reactor. [Reference to Related Application] This application claims the benefit of priority from Japanese Patent Application JP2022-017640, filed on February 8, 2022, the entire disclosure of which is incorporated herein by reference. [Background technology]

[0002] In recent years, various technologies have been proposed to fix carbon dioxide in exhaust gases from power plants and the like in order to reduce greenhouse gases. For example, one such technology that has attracted attention is a technology that reacts carbon dioxide in exhaust gases with hydrogen to produce methane (i.e., methanation). This methanation is carried out using a membrane reactor that combines a separation membrane and a catalyst, as described in JP 2018-008940 A (Reference 1).

[0003] In a membrane reactor, reactants generated from raw materials in a chemical reaction in the presence of a catalyst are removed by a separation membrane. This shifts the reaction equilibrium of the chemical reaction toward the reactants, improving the efficiency of reactant production. Membrane reactors are also used for purposes other than methanation, and membrane reactors with various structures have been proposed (see JP 2019-156658 A (Reference 2) and JP 2020-040030 A (Reference 3)).

[0004] Incidentally, a monolithic separation membrane composite is known as one type of separation membrane that separates a specific substance from multiple types of substances. This separation membrane composite comprises a monolithic porous support having multiple cells and a cylindrical separation membrane attached to the inner surface of the cells. When using such a separation membrane composite in a membrane reactor, it is conceivable to fill the multiple cells (i.e., the space inside the cylindrical separation membrane) with a catalyst. However, because membrane reactors are generally operated at relatively high temperatures, stress due to thermal expansion may occur due to differences in the thermal expansion coefficients and the ease of heating and cooling between the separation membrane composite and the catalyst during temperature rise and fall, which may result in damage to the separation membrane. Summary of the Invention

[0005] The present invention is directed to a membrane reactor, and aims to suppress breakage of the separation membrane caused by the difference in the thermal expansion coefficient between the catalyst and the separation membrane composite.

[0006] A preferred embodiment of the present invention provides a membrane reactor comprising a separation membrane composite including a separation membrane and a porous support, and a catalyst for promoting a chemical reaction of a raw material. The support is cylindrical and extends in the longitudinal direction. The support is provided with a membrane formation cell that is open at least at one end in the longitudinal direction and has the separation membrane disposed on its inner surface. The catalyst is disposed within the membrane formation cell of the separation membrane composite. The ratio of the average particle size of the catalyst to the inner diameter of the membrane formation cell is 0.75 or more and less than 1.

[0007] According to the membrane reactor, it is possible to suppress breakage of the separation membrane caused by the difference in the thermal expansion coefficient between the catalyst and the separation membrane composite.

[0008] Preferably, the ratio of the average particle size of the catalyst to the inner diameter of the deposition cell is 0.85 or more and less than 1.

[0009] Preferably, the inner diameter of the film deposition cell is 0.2 mm or more and 10 mm or less.

[0010] Preferably, the cross section of the film deposition cell perpendicular to the longitudinal direction has a circular shape.

[0011] Preferably, the deposition cell is open at both ends in the longitudinal direction.

[0012] Preferably, the separation membrane is a zeolite membrane.

[0013] Preferably, the maximum number of rings in the zeolite constituting the zeolite membrane is 8 or less.

[0014] The present invention is also directed to a method for operating a membrane reactor. In a preferred embodiment of the method for operating a membrane reactor of the present invention, the membrane reactor comprises a membrane reactor and a housing that houses the membrane reactor. The membrane reactor comprises a separation membrane composite including a separation membrane and a porous support, and a catalyst that promotes a chemical reaction of a raw material. The support is cylindrical and extends in the longitudinal direction. The support is provided with a membrane formation cell that is open at at least one end in the longitudinal direction and in which the separation membrane is disposed on the inner surface. The catalyst is disposed in the membrane formation cell of the separation membrane composite. The ratio of the average particle size of the catalyst to the inner diameter of the membrane formation cell is 0.75 or more and less than 1. The method for operating the membrane reactor includes the steps of: a) supplying raw materials to the membrane-forming cell of the separation membrane composite, generating reactants by chemically reacting the raw materials in the presence of the catalyst in an environment of 150°C or higher, and separating highly permeable substances from the reactants by passing them through the separation membrane; and b) cooling the membrane reactor to 40°C or lower.

[0015] The above and other objects, features, aspects and advantages will become more apparent from the following detailed description of the invention which proceeds with reference to the accompanying drawings. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a perspective view of a membrane reactor according to one embodiment. [Figure 2]FIG. 1 shows an end view of a membrane reactor. [Figure 3] FIG. 2 is a perspective view of a separation membrane composite. [Figure 4] FIG. 2 is a view showing an end face of a separation membrane composite. [Figure 5] FIG. 2 is a cross-sectional view of a separation membrane composite. [Figure 6] FIG. 1 is a cross-sectional view of a membrane reactor. [Figure 7] FIG. 10 is a diagram showing another example of an end face of a separation membrane composite. [Figure 8] FIG. 1 is a diagram showing the manufacturing flow of a membrane reactor. [Figure 9] FIG. 1 shows a membrane reactor. [Figure 10] FIG. 1 is a diagram showing a method of operating a membrane reactor. DETAILED DESCRIPTION OF THE INVENTION

[0017] FIG. 1 is a perspective view of a membrane reactor 4 according to one embodiment of the present invention. FIG. 2 is a view showing one end face in the longitudinal direction (i.e., approximately the left-right direction in FIG. 1) of the membrane reactor 4. The membrane reactor 4 includes a separation membrane composite 1 and a catalyst 41 supported on the separation membrane composite 1. The membrane reactor 4 generates reactants by chemically reacting raw materials in the presence of the catalyst 41. The catalyst 41 is a substance that promotes the chemical reaction of the raw materials. In the membrane reactor 4, among the reactants, substances that have high permeability to a separation membrane (described later) are separated from the raw materials by passing through the separation membrane. This further promotes the chemical reaction of the raw materials in the membrane reactor 4.

[0018] FIG. 3 is a perspective view of the separation membrane composite 1. FIG. 3 also shows part of the internal structure of the separation membrane composite 1. FIG. 4 is a diagram showing one end surface 114 in the longitudinal direction (i.e., approximately the left-right direction in FIG. 3) of the separation membrane composite 1. FIG. 5 is an enlarged view of a portion of the longitudinal cross section of the separation membrane composite 1, showing the vicinity of a cell 111, which will be described later. The separation membrane composite 1 separates a specific substance from a mixture of multiple types of substances.

[0019] The separation membrane composite 1 includes a porous support 11 and a separation membrane 12 (see FIG. 5) formed on the support 11. In FIG. 5, the separation membrane 12 is indicated by hatching (the same applies to FIG. 6, which will be described later). The support 11 is a porous member that is permeable to gas and liquid. In the example shown in FIG. 3, the support 11 is a monolithic support having an integrally molded, continuous columnar body with a plurality of through-holes 111 (hereinafter also referred to as "cells 111") extending in the longitudinal direction of the body. In the support 11, a plurality of cells 111 are formed (i.e., partitioned) by porous partition walls. In the example shown in FIG. 3, the outer shape of the support 11 is approximately cylindrical. The cross-sectional shape of each cell 111 perpendicular to the longitudinal direction is, for example, approximately circular. Note that the term "approximately circular" is a concept that includes not only a perfect circle but also an ellipse or a distorted circle. The cross-sectional shape of each cell 111 is preferably, but not necessarily, a perfect circle. The inner diameter of the cell 111 means the maximum diameter of a circle inscribed in the cross-sectional shape. In Fig. 3, the diameter of the cell 111 is drawn larger than the actual diameter, and the number of the cells 111 is drawn smaller than the actual number (the same applies to Figs. 1, 2, and 4).

[0020] The multiple cells 111 include first cells 111a and second cells 111b. In the example shown in FIGS. 1 to 4, the first cells 111a and the second cells 111b have approximately the same shape. At both longitudinal end faces 114 of the support body 11, the openings of the second cells 111b are plugged with plugging members 115. In other words, the second cells 111b are closed at both longitudinal ends. In FIGS. 1 to 4, the plugging members 115 are indicated by diagonal lines. On the other hand, at both longitudinal end faces 114 of the support body 11, the openings of the first cells 111a are not plugged and are open.

[0021] The above-mentioned separation membrane 12 (see FIG. 5) is disposed on the inner surface of each first cell 111a, which is open at both longitudinal ends. The separation membrane 12 is preferably provided so as to cover the entire inner surface of each first cell 111a. That is, the first cell 111a is a membrane cell provided with the separation membrane 12 on the inside. In the separation membrane composite 1, the separation membrane 12 is not provided on the inside of the second cell 111b.

[0022] In the membrane reactor 4, as shown in FIG. 2, a substantially spherical catalyst 41 is placed in the first cell 111a. Note that no catalyst 41 is placed in the second cell 111b. The catalyst 41 has a particle diameter smaller than the inner diameter of the first cell 111a when viewed along the longitudinal direction of the membrane reactor 4. In the membrane reactor 4, a large number of particles of the catalyst 41 are filled in the first cell 111a. The particles of the catalyst 41 are formed, for example, by granulating fine powder of the catalyst 41. The shape and particle diameter of the catalyst 41 are adjusted, for example, during granulation or molding. A known catalyst suitable for each reaction can be used as the catalyst 41; for example, a zirconia-supported nickel catalyst for methanation (i.e., a catalyst in which nickel (Ni) is supported on stabilized zirconia) is used. The type of catalyst 41 is not limited to this example and may be variously changed.

[0023] In the membrane reactor 4, a filler that does not plug the opening of the first cell 111a may be provided at both ends or one end of the first cell 111a in the longitudinal direction to prevent or suppress particles of the catalyst 41 from falling out of the first cell 111a. The filler is formed of a flexible material such as heat-resistant wool, and partially blocks the opening of the first cell 111a without substantially impeding the passage of gas and liquid. When the temperature of the membrane reactor 4 rises and the catalyst 41 thermally expands, the filler is easily deformed even when pressed by the catalyst 41.

[0024] The inner diameter of the first cell 111a is, for example, 0.2 mm or more and 10 mm or less. The inner diameter of the first cell 111a here refers to the inner diameter of the first cell 111a taking into consideration the thickness of the separation membrane 12. In other words, the inner diameter of the substantially cylindrical separation membrane 12 formed on the inner surface of the first cell 111a is, for example, 0.2 mm or more and 10 mm or less.

[0025] The catalyst 41 may have a variety of shapes. Examples of the shape of the catalyst 41 include a sphere, an ellipsoid, a cylinder (a circular cylinder, a rectangular cylinder, an oblique cylinder, an oblique rectangular cylinder, etc.), and a pyramid (a cone, a pyramid, etc.). The catalyst 41 is preferably spherical, ellipsoidal, or cylindrical because it can efficiently fill the inside of the first cell 111a without damaging the separation membrane 12. When the catalyst 41 is spherical, the particle size of the catalyst 41 is the diameter of the sphere (or the average diameter if the catalyst 41 is approximately spherical). When the catalyst 41 is ellipsoidal, the particle size of the catalyst 41 is the maximum diameter of a circle circumscribing a cross section perpendicular to the major axis of the ellipsoid. When the catalyst 41 is cylindrical, the particle size of the catalyst 41 is the maximum diameter of a circle circumscribing a cross section perpendicular to an axis parallel to the side surface. When the catalyst 41 is conical, the particle size of the catalyst 41 is the maximum diameter of a circle circumscribing a bottom surface. The average particle size of the catalyst 41 is the median diameter (D 50 In this embodiment, the catalyst 41 is substantially spherical.

[0026] The ratio of the average particle size of the catalyst 41 to the inner diameter of the first cell 111a (hereinafter also referred to as the "catalyst particle size ratio") is, for example, 0.75 or more and less than 1, preferably 0.85 or more and less than 1. By setting the catalyst particle size ratio to less than 1, the particles of the catalyst 41 can be easily filled into the first cell 111a. Furthermore, by setting the catalyst particle size ratio to 0.75 or more, as shown in FIG. 6, multiple particles of the catalyst 41 are arranged one by one along the longitudinal direction (i.e., the left-right direction in FIG. 6) in the first cell 111a, and two or more particles of the catalyst 41 are prevented from being arranged at approximately the same position in the longitudinal direction. In other words, two or more particles of the catalyst 41 are prevented from being arranged side by side in a direction perpendicular to the longitudinal direction in the first cell 111a. FIG. 6 is an enlarged view of a portion of the longitudinal cross section of the membrane reactor 4, with the support 11 not shown. In the example shown in FIG. 6, each particle of catalyst 41 contacts separation membrane 12 and adjacent particles of catalyst 41 in the longitudinal direction.

[0027] The particle size distribution of the catalyst 41 is measured after a large number of particles of the catalyst 41 are sieved to remove minute fragments, etc. The opening of the sieve is 1 / 20 of the inner diameter of the first cell 111a. This makes it possible to prevent minute fragments, etc. of the catalyst 41 from affecting the calculation of the average particle size of the catalyst 41.

[0028] In the example shown in Figures 3 and 4, the multiple cells 111 are arranged in a matrix on the end surface 114 of the support 11 in the vertical direction (i.e., the up-and-down direction in Figure 4) and the horizontal direction. In the following description, a group of cells 111 arranged in a row in the horizontal direction (i.e., the left-and-right direction in Figure 4) will also be referred to as a "cell row." The multiple cells 111 include multiple rows of cell rows arranged in the vertical direction. In the example shown in Figure 4, each row of cell rows is composed of multiple first cells 111a or multiple second cells 111b.

[0029] In the example shown in FIG. 4, in the multiple cell rows, a cell row of second cells 111b in one row (hereinafter also referred to as "second cell row 116b") and a cell row of first cells 111a in two rows (hereinafter also referred to as "first cell row 116a") are arranged adjacent to each other in the vertical direction and alternately. In FIG. 4, each first cell row 116a and each second cell row 116b are indicated by being surrounded by a two-dot chain line (the same applies to FIG. 7 described later). The second cell row 116b is a plugged cell row in which both ends in the longitudinal direction are plugged. The multiple second cells 111b in the second cell row 116b are connected by slits 117 (see FIGS. 1 and 3) extending along the horizontal direction. The slits 117 extend to the outer surface 112 of the support 11 on both lateral sides of the second cell row 116b, and the second cells 111b of the second cell row 116b communicate with the space outside the support 11 through the slits 117. In other words, the slits 117 extend from the outer surface of the support 11 to penetrate the second cell row 116b in the lateral direction.

[0030] The first cell row 116a is an open cell row with both longitudinal ends open and is also a deposition cell row with a separation membrane 12 (see FIG. 5) provided inside. The two rows of first cells 111a adjacent to one side of the second cell row 116b in the vertical direction constitute an open cell row group. In other words, the open cell row group is the two rows of first cell rows 116a sandwiched between the two second cell rows 116b positioned closest to each other in the vertical direction. The number of rows of first cell rows 116a constituting the open cell row group is not limited to two and may be varied. Preferably, the number of rows of first cell rows 116a constituting the open cell row group is one or more and six or less, more preferably one or two. FIG. 7 shows an example in which the number of rows of first cell rows 116a constituting the open cell row group sandwiched between two second cell rows 116b is five.

[0031] The length of the support 11 in the longitudinal direction is, for example, 100 mm to 2000 mm. The outer diameter of the support 11 is, for example, 5 mm to 300 mm. The distance between adjacent cells 111 (i.e., the thickness of the support 11 between the closest portions of the adjacent cells 111) is, for example, 0.3 mm to 10 mm. The surface roughness (Ra) of the inner surface of the first cells 111a of the support 11 is, for example, 0.1 μm to 5.0 μm, and preferably 0.2 μm to 2.0 μm.

[0032] The shapes and sizes of the support 11 and the cells 111 may be varied in various ways. For example, the cross-sectional shape of the cell 111 perpendicular to the longitudinal direction may be substantially polygonal. In this case, the inner diameter of the first cell 111a refers to the maximum diameter of a circle inscribed in the cross-sectional shape. The shapes and sizes of the first cell 111a and the second cell 111b may be different. Furthermore, the shapes and sizes of some or all of the first cells 111a may be different from each other, and the shapes and sizes of some or all of the second cells 111b may be different from each other. Furthermore, when the inner diameters of some or all of the first cells 111a are different, the arithmetic mean of the inner diameters of all the first cells 111a is defined as the inner diameter of the first cell 111a.

[0033] The material of the support 11 can be various substances (for example, ceramic or metal) as long as they are chemically stable in the process of forming the separation membrane 12 on the surface. In this embodiment, the support 11 is formed of a ceramic sintered body. Examples of ceramic sintered bodies selected as the material of the support 11 include alumina, silica, mullite, zirconia, titania, yttria, silicon nitride, and silicon carbide, and it is preferable that the support 11 contains at least one of alumina, silica, and mullite. In this embodiment, the support 11 is alumina.

[0034] The support 11 may contain an inorganic binder for binding aggregate particles of the ceramic sintered body, which may be at least one of titania, mullite, sinterable alumina, silica, glass frit, clay minerals, and sinterable cordierite.

[0035] The support 11 has a multilayer structure in which multiple layers with different average pore sizes are stacked in the thickness direction near the inner surface of each of the first cells 111a, which are open cells (i.e., near the separation membrane 12). In the example shown in FIG. 5, the support 11 includes a porous substrate 31, a porous intermediate layer 32 formed on the substrate 31, and a porous surface layer 33 formed on the intermediate layer 32. That is, the surface layer 33 is indirectly provided on the substrate 31 via the intermediate layer 32. The intermediate layer 32 is also provided between the substrate 31 and the surface layer 33. The surface layer 33 constitutes the inner surface of each of the first cells 111a of the support 11, and the separation membrane 12 is formed on the surface layer 33. The thickness of the surface layer 33 is, for example, 1 μm to 100 μm. The thickness of the intermediate layer 32 is, for example, 100 μm to 500 μm. The intermediate layer 32 and the surface layer 33 may or may not be provided on the inner surface of each second cell 111b. The intermediate layer 32 and the surface layer 33 may or may not be provided on the outer surface 112 and the end surface 114 of the support 11.

[0036] The average pore diameter of the surface layer 33 is smaller than the average pore diameter of the intermediate layer 32 and the average pore diameter of the substrate 31. The average pore diameter of the intermediate layer 32 is also smaller than the average pore diameter of the substrate 31. The average pore diameter of the substrate 31 is, for example, 1 μm or more and 70 μm or less. The average pore diameter of the intermediate layer 32 is, for example, 0.1 μm or more and 10 μm or less. The average pore diameter of the surface layer 33 is, for example, 0.005 μm or more and 2 μm or less. The average pore diameters of the substrate 31, intermediate layer 32, and surface layer 33 can be measured, for example, by a mercury porosimeter, a perm porometer, or a nanoperm porometer.

[0037] The surface layer 33, the intermediate layer 32, and the substrate 31 have substantially the same porosity. The porosity of the surface layer 33, the intermediate layer 32, and the substrate 31 is, for example, 15% or more and 70% or less. The porosity of the surface layer 33, the intermediate layer 32, and the substrate 31 can be measured by, for example, the Archimedes method, the mercury porosity method, or an image analysis method.

[0038] The substrate 31, intermediate layer 32, and surface layer 33 may be formed of the same material or different materials. For example, the substrate 31 and surface layer 33 contain Al2O3 as a main material. The intermediate layer 32 contains aggregate particles mainly made of Al2O3 and an inorganic binder mainly made of TiO2. In this embodiment, the aggregate particles of the substrate 31, intermediate layer 32, and surface layer 33 are formed substantially only from Al2O3. The substrate 31 may contain an inorganic binder such as glass.

[0039] The average particle size of the aggregate particles in the surface layer 33 is smaller than the average particle size of the aggregate particles in the intermediate layer 32. The average particle size of the aggregate particles in the intermediate layer 32 is also smaller than the average particle size of the aggregate particles in the base material 31. The average particle sizes of the aggregate particles in the base material 31, intermediate layer 32, and surface layer 33 can be measured by, for example, laser diffraction.

[0040] The plugging member 115 can be formed from the same material as the base material 31, the intermediate layer 32, and the surface layer 33. The porosity of the plugging member 115 is, for example, 15% to 70%.

[0041] As described above, the separation membrane 12 is formed on the inner surface of each first cell 111a, which is an open cell (i.e., on the surface layer 33), and covers the inner surface over substantially the entire surface. The separation membrane 12 is a porous membrane having micropores. The separation membrane 12 separates a specific substance from a mixture of multiple types of substances.

[0042] Separation membrane 12 is preferably an inorganic membrane formed from an inorganic material, more preferably a zeolite membrane, silica membrane, carbon membrane, or MOF (metal-organic composite) membrane, and particularly preferably a zeolite membrane. A zeolite membrane is at least a membrane of zeolite formed on the surface of support 11, and does not include an organic membrane in which zeolite particles are simply dispersed. In this embodiment, separation membrane 12 is a zeolite membrane. Separation membrane 12 may also be a zeolite membrane containing two or more types of zeolites with different structures and compositions.

[0043] The thickness of the separation membrane 12 is, for example, 0.05 μm or more and 50 μm or less, preferably 0.1 μm or more and 20 μm or less, and more preferably 0.5 μm or more and 10 μm or less. Increasing the thickness of the separation membrane 12 improves separation performance. Reducing the thickness of the separation membrane 12 increases the permeation rate. The surface roughness (Ra) of the separation membrane 12 is, for example, 5 μm or less, preferably 2 μm or less, more preferably 1 μm or less, and even more preferably 0.5 μm or less. The pore diameter of the separation membrane 12 is, for example, 0.2 nm to 1 nm. The pore diameter of the separation membrane 12 is smaller than the average pore diameter of the surface layer 33 of the support 11.

[0044] When the maximum number of rings in the zeolite constituting the separation membrane 12 is n, the minor axis of the n-membered ring pore is defined as the pore diameter of the separation membrane 12. When the zeolite has multiple types of n-membered ring pores with the same n, the minor axis of the n-membered ring pore with the largest minor axis is defined as the pore diameter of the separation membrane 12. Note that an n-membered ring refers to a portion in which the number of oxygen atoms constituting the skeleton forming the pore is n, and each oxygen atom is bonded to a T atom (described below) to form a ring structure. Note that an n-membered ring refers to a ring that forms a through-hole (channel), and does not include a ring that does not form a through-hole. An n-membered ring pore is a pore formed by an n-membered ring. From the viewpoint of improving selectivity, the maximum number of rings in the zeolite constituting the separation membrane 12 is preferably 8 or less (for example, 6 or 8).

[0045] The pore size of the separation membrane 12 is primarily determined by the framework structure of the zeolite.<URL:http: / / www.iza-structure.org / databases / > The values ​​can be obtained from the values ​​disclosed in

[0046] The type of zeolite constituting separation membrane 12 is not particularly limited, and may be, for example, AEI, AEN, AFN, AFV, AFX, BEA, CHA, DDR, ERI, ETL, FAU (X, Y), GIS, IHW, LEV, LTA, LTJ, MEL, MFI, MOR, PAU, RHO, SOD, or SAT zeolite. When the zeolite is an eight-membered ring zeolite, it may be, for example, AEI, AFN, AFV, AFX, CHA, DDR, ERI, ETL, GIS, IHW, LEV, LTA, LTJ, RHO, or SAT zeolite. In this embodiment, the type of zeolite constituting separation membrane 12 is DDR zeolite.

[0047] The zeolite constituting the separation membrane 12 contains at least one of silicon (Si), aluminum (Al), and phosphorus (P) as a T atom (i.e., an atom located at the center of an oxygen tetrahedron (TO4) constituting the zeolite). Zeolites constituting the separation membrane 12 include zeolites in which the T atom is Si only or contains Si and Al, AlPO zeolites in which the T atom is Al and P, SAPO zeolites in which the T atom is Si, Al, and P, MAPSO zeolites in which the T atom is magnesium (Mg), Si, Al, and P, and ZnAPSO zeolites in which the T atom is zinc (Zn), Si, Al, and P. Some of the T atoms may be substituted with other elements. The zeolite constituting the separation membrane 12 may contain an alkali metal. The alkali metal is, for example, sodium (Na) or potassium (K).

[0048] When the zeolite constituting separation membrane 12 contains Si atoms and Al atoms, the Si / Al ratio in the zeolite constituting separation membrane 12 is, for example, 1 or more and 100,000 or less. The Si / Al ratio is the molar ratio of Si element to Al element contained in the zeolite constituting separation membrane 12. The Si / Al ratio is preferably 5 or more, more preferably 20 or more, and even more preferably 100 or more; the higher the Si / Al ratio, the higher the heat resistance and acid resistance of separation membrane 12, which is preferable. The Si / Al ratio can be adjusted by adjusting the compounding ratio of the Si source and Al source in the raw material solution, which will be described later.

[0049] Next, with reference to FIG. 8, an example of the manufacturing flow of the membrane reactor 4 will be described. When manufacturing the membrane reactor 4, first, a separation membrane composite 1 is manufactured. In manufacturing the separation membrane composite 1, seed crystals to be used in forming the separation membrane 12 are first generated and prepared (step S11). In generating the seed crystals, raw materials such as a Si source and a structure-directing agent (hereinafter also referred to as "SDA") are dissolved or dispersed in a solvent to prepare a raw material solution of the seed crystals. Subsequently, hydrothermal synthesis of the raw material solution is performed, and the obtained crystals are washed and dried to obtain zeolite powder. The zeolite powder may be used as the seed crystals as is, or the seed crystals may be obtained by processing the powder by pulverization or the like.

[0050] Next, a dispersion liquid in which seed crystals are dispersed in a solvent (e.g., water) is brought into contact with the inner surfaces of the first cells 111a of the support 11, thereby attaching the seed crystals in the dispersion liquid to the inner surfaces of the first cells 111a (step S12). Note that the seed crystals may also be attached to the inner surfaces of the first cells 111a by other methods. When step S12 is performed, for example, both longitudinal ends of the second cells 111b are plugged in advance.

[0051] Next, the support 11 with the seed crystal attached thereto is immersed in a raw material solution. The raw material solution is prepared by dissolving, for example, a Si source and SDA in a solvent. The solvent for the raw material solution is, for example, water or an alcohol such as ethanol. The SDA contained in the raw material solution is, for example, an organic substance. For example, 1-adamantanamine can be used as the SDA.

[0052] Then, zeolite is grown by hydrothermal synthesis using the seed crystals as nuclei, thereby forming separation membrane 12 on the inner surface of each first cell 111a of support 11 (step S13). The temperature during hydrothermal synthesis is preferably 120 to 200°C, for example, 160°C. The hydrothermal synthesis time is preferably 5 to 100 hours, for example, 30 hours.

[0053] After the hydrothermal synthesis is complete, the support 11 and the separation membrane 12 are washed with pure water. After the washing, the support 11 and the separation membrane 12 are dried, for example, at 80°C. After the support 11 and the separation membrane 12 are dried, the separation membrane 12 is heat-treated (i.e., calcined) to almost completely burn off the SDA in the separation membrane 12 and penetrate the micropores in the separation membrane 12. This results in the above-described separation membrane composite 1 (step S14).

[0054] Thereafter, particles of the catalyst 41 are filled into the first cells 111a of the separation membrane composite 1. In this way, the above-mentioned membrane reactor 4 is obtained (step S15).

[0055] Next, a method for operating the membrane reactor 2 equipped with the above-mentioned membrane reactor 4 will be described with reference to Fig. 9 and Fig. 10. Fig. 9 is a cross-sectional view showing the membrane reactor 2. In Fig. 9, the cross section of the membrane reactor 4 is shown conceptually in a simplified form to facilitate understanding of the drawing. Fig. 10 is a diagram showing the flow of operation of the membrane reactor 2.

[0056] In the membrane reactor 2, a fluid that is a raw material is supplied to the membrane reactor 4, and the raw material undergoes a chemical reaction in the presence of a catalyst 41 to produce a reactant. Among the reactants, those that have a high permeability to the separation membrane 12 (hereinafter also referred to as "highly permeable substances") permeate the separation membrane composite 1 and are separated from the raw material. This promotes the chemical reaction of the raw material in the membrane reactor 4. Among the reactants, those that have a low permeability to the separation membrane 12 (hereinafter also referred to as "lowly permeable substances") are less likely to permeate the separation membrane 12 and are less likely to be separated from the raw material. Note that the reactants do not necessarily need to contain lowly permeable substances.

[0057] The source material may be a single type of gas or liquid, a mixed gas containing multiple types of gases, a mixed liquid containing multiple types of liquids, or a gas-liquid two-phase fluid containing both gas and liquid.

[0058] In the following description, it is assumed that the raw material supplied to the membrane reactor 2 is a mixed gas containing multiple types of gases, and that the reactants generated from the raw material are also mixed gases containing multiple types of gases. The raw material is, for example, a mixed gas containing carbon dioxide (CO2) and hydrogen (H2), and methane (CH4) and water (H2O) are generated as reactants through a chemical reaction in the membrane reactor 2. That is, methanation is performed in the membrane reactor 2. Of the reactants, H2O, which is a highly permeable substance, permeates the separation membrane 12, while CH4, which is a low-permeable substance, does not permeate the separation membrane 12. The catalyst 41 used in the above chemical reaction is, for example, a zirconia-supported nickel catalyst.

[0059] The membrane reaction apparatus 2 includes a membrane reactor 4, a sealing unit 21, a housing 22, and two sealing members 23. The membrane reactor 4, the sealing unit 21, and the sealing members 23 are housed in the housing 22. In FIG. 9, the separation membrane 12 of the membrane reactor 4 is indicated by hatching. The internal space of the housing 22 is an enclosed space isolated from the space surrounding the housing 22. A supply unit 26, a first recovery unit 27, and a second recovery unit 28 are connected to the housing 22.

[0060] The sealing portions 21 are provided at both longitudinal ends of the support 11 of the membrane reactor 4 (i.e., the left-right direction in FIG. 9 ) and are members that cover and seal both longitudinal end faces 114 of the support 11 and parts of the outer surfaces 112 near the both end faces 114. The sealing portions 21 prevent the inflow and outflow of gas and liquid from the both end faces 114 of the support 11. The sealing portions 21 are, for example, sealing layers made of glass or resin. In this embodiment, the sealing portions 21 are glass seals with a thickness of 10 μm to 50 μm. The material and shape of the sealing portions 21 may be changed as appropriate. Note that the sealing portions 21 have multiple openings that overlap with the multiple first cells 111a of the support 11, and therefore both longitudinal ends of each first cell 111a are not covered by the sealing portions 21. Therefore, fluids can flow into and out of the first cells 111a from the both ends.

[0061] The housing 22 is a substantially cylindrical tubular member. The housing 22 is formed of, for example, stainless steel or carbon steel. The longitudinal direction of the housing 22 is substantially parallel to the longitudinal directions of the membrane reactor 4 and the separation membrane composite 1. A supply port 221 is provided at one longitudinal end of the housing 22 (i.e., the left end in FIG. 9 ), and a first discharge port 222 is provided at the other end. A second discharge port 223 is provided on the side of the housing 22. The supply port 221 is connected to the supply section 26. The first discharge port 222 is connected to the first collection section 27. The second discharge port 223 is connected to the second collection section 28. The shape and material of the housing 22 may be modified in various ways.

[0062] Two seal members 23 are disposed around the entire circumference between the outer surface 112 of the separation membrane composite 1 and the inner surface of the housing 22 near both longitudinal ends of the membrane reactor 4. Each seal member 23 is a substantially annular member made of a material impermeable to gases and liquids. The seal members 23 are, for example, O-rings or packings made of flexible resin. The seal members 23 are in close contact with the outer surface 112 of the separation membrane composite 1 and the inner surface of the housing 22 around the entire circumference. In the example shown in FIG. 9 , the seal member 23 is in close contact with the outer surface of the sealing portion 21 between the end surface 114 of the support 11 and the slit 117, and is indirectly in close contact with the outer surface 112 of the separation membrane composite 1 via the sealing portion 21. A seal is formed between the seal member 23 and the outer surface 112 of the separation membrane composite 1, and between the seal member 23 and the inner surface of the housing 22, substantially preventing the passage of gases and liquids. The material of the seal member 23 may be carbon, metal, or other inorganic material other than resin.

[0063] Supply unit 26 supplies the raw material, which is a mixed gas, to the internal space of housing 22 via supply port 221. Supply unit 26 includes a pressure-transfer mechanism such as a blower or pump that pressure-transfers the raw material toward housing 22. The pressure-transfer mechanism includes, for example, a temperature adjustment unit and a pressure adjustment unit that respectively adjust the temperature and pressure of the raw material supplied to housing 22. First recovery unit 27 and second recovery unit 28 include, for example, a storage container that stores the gas drawn out from housing 22, or a blower or pump that transports the gas.

[0064] In operation of the membrane reaction apparatus 2, first, the membrane reactor 4 is prepared (step S21). Specifically, the membrane reactor 4 is attached inside the housing 22. Subsequently, the supply unit 26 supplies a mixed gas of raw material into the housing 22 as indicated by arrow 251 (specifically, into the space to the left of the left end face 114 of the separation membrane composite 1). The raw material includes, for example, CO2 and H2. The raw material may include substances other than CO2 and H2. The pressure (i.e., the introduction pressure) of the raw material supplied from the supply unit 26 to the inside of the housing 22 is, for example, 0.1 MPa to 20 MPa. The temperature of the raw material supplied from the supply unit 26 to the inside of the housing 22 is, for example, 10°C to 500°C. In the membrane reaction apparatus 2, the inside of the housing 22 is preheated, and the membrane reactor 4 is heated to a temperature (for example, 150°C to 500°C) suitable for the chemical reaction of the raw material. The temperature of the membrane reactor 4 is maintained at that temperature while the chemical reaction of the raw materials takes place.

[0065] The raw materials (e.g., CO2 and H2) supplied from the supply unit 26 to the housing 22 flow into each first cell 111a of the separation membrane composite 1. Within each first cell 111a, the raw materials undergo a chemical reaction in the presence of the catalyst 41 in a high-temperature environment of 150°C or higher to produce reactants (e.g., CH4 and HO). As indicated by arrow 252a, highly permeable substances (e.g., HO) among the reactants permeate from the first cell 111a through the separation membrane 12 and the support 11, and are discharged from the outer surface 112 of the separation membrane composite 1 into a separation space 220 around the separation membrane composite 1. The separation space 220 is located radially outward of the outer surface 112 of the separation membrane composite 1 and is a substantially cylindrical space sandwiched between two seal members 23.

[0066] More specifically, as indicated by arrow 252b, the highly permeable substance that has permeated from the first cell 111a through the separation membrane 12 and the support 11 and flowed into the second cell 111b is guided to the outer surface 112 of the separation membrane composite 1 through the slit 117 as indicated by arrow 252c, and is then discharged into the separation space 220. The highly permeable substance that has flowed from the first cell 111a into the second cell 111b may also be discharged into the separation space 220 by permeating the support 11 without passing through the slit 117. In the separation membrane composite 1, the end surface 114 of the support 11 is covered with the sealing portion 21, which prevents or inhibits the raw material from entering the inside of the support 11 through the end surface 114 and then entering the separation space 220 without permeating the separation membrane 12.

[0067] In this way, the highly permeable substances permeate the separation membrane 12 and are discharged into the separation space 220, whereby the highly permeable substances (e.g., HO) are separated from other substances, such as the raw materials (e.g., CO and H) and the low-permeable substances (e.g., CH) in the reactants (step S22). The substances discharged from the outer surface 112 of the separation membrane composite 1 (hereinafter referred to as "permeated substances") are discharged to the second recovery section 28 via the second discharge port 223, as indicated by arrow 253 in FIG. 9, and recovered. In addition to the highly permeable substances described above, the permeated substances may also include low-permeable substances that have permeated the separation membrane 12 and components of the raw materials.

[0068] The raw material and reactants, excluding the permeated material (hereinafter referred to as "non-permeated material"), are guided to the first recovery section 27 via the first discharge port 222 as indicated by the arrow 254 and recovered. The non-permeated material may include a highly permeable material that did not permeate the separation membrane 12, in addition to a low-permeable material and the raw material that was not consumed in the chemical reaction. The non-permeated material recovered by the first recovery section 27 is separated into the raw material and the low-permeable material by, for example, a separation device (not shown). The raw material separated by the separation device may be circulated to the supply section 26 and supplied again into the housing 22. The low-permeable material (e.g., CH4) separated by the separation device may be recovered and used for various purposes.

[0069] In the membrane reactor 2, when the supply of the raw materials is completed, heating of the housing 22 is stopped and the temperature of the membrane reactor 4 is lowered. The temperature of the membrane reactor 4 is lowered to a temperature of 40°C or less (for example, room temperature) (step S23), thereby terminating the operation of the membrane reactor 2. The temperature of the membrane reactor 4 in step S23 may be lowered by natural cooling or by forced cooling using a blown air or a refrigerant, etc.

[0070] In this way, when the membrane reactor 2 is operated, the temperature of the membrane reactor 4 is raised and lowered between a temperature of 40°C or lower and a temperature of 150°C or higher. When the temperature of the membrane reactor 4 is raised and lowered, stress due to the difference in the thermal expansion coefficient between the separation membrane composite 1 and the catalyst 41 may occur between the separation membrane composite 1 and the catalyst 41, and between particles of the catalyst 41. For example, if a particle diameter of the first cell 111a is half the inner diameter of the first cell 111a, Two When the particles of the catalyst 41 are arranged side by side at approximately the same position in the longitudinal direction of the first cell 111a, if the thermal expansion of the catalyst 41 is larger than the thermal expansion of the separation membrane 12 when the temperature rises, TwoStress is generated between particles of catalyst 41 in a direction approximately perpendicular to the longitudinal direction of first cell 111a. Furthermore, if the thermal contraction of separation membrane 12 during temperature drop is greater than the thermal contraction of catalyst 41, approximately the same stress is generated. When this stress is generated, a force is applied to separation membrane 12 in a radially outward direction (i.e., in a radially outward direction about the central axis extending in the longitudinal direction of first cell 111a), pressing separation membrane 12 against support 11, which may result in damage to separation membrane 12.

[0071] In contrast, in the membrane reactor 4 according to the present invention, as described above, by setting the catalyst particle size ratio (i.e., the ratio of the average particle size of the catalyst 41 to the inner diameter of the first cell 111a) to 0.75 or more, multiple particles of the catalyst 41 are arranged one by one along the longitudinal direction within the first cell 111a, and the arrangement of two or more particles of the catalyst 41 at approximately the same position in the longitudinal direction is suppressed. As a result, even if the thermal expansion of the catalyst 41 during temperature rise is greater than the thermal expansion of the separation membrane 12, the stress generated between the particles of the catalyst 41 is directed along the longitudinal direction of the first cell 111a. Furthermore, because both ends of the first cell 111a in the longitudinal direction are open, the stress escapes through the openings and is substantially not directed in a direction perpendicular to the longitudinal direction. The same applies when the thermal contraction of the separation membrane 12 during temperature fall is greater than that of the catalyst 41. Therefore, almost no force is applied to separation membrane 12 in the radially outward direction, and damage to separation membrane 12 due to differences in the thermal expansion coefficients between catalyst 41 and separation membrane composite 1 is suppressed.

[0072] Next, with reference to Table 1, the relationship between the catalyst particle size ratio in the membrane reactor 4 of Examples 1 to 3 and the characteristics of the membrane reactor 4 will be described. The same applies to Comparative Example 1.

[0073] [Table 1]

[0074] In Example 1, a separation membrane composite 1 was produced by a manufacturing method similar to steps S11 to S14 described above. The support 11 was made of alumina and had an outer diameter of 30 mm. The separation membrane 12 in each first cell 111a was a DDR-type zeolite membrane. The inner diameter of each first cell 111a was 2.0 mm. Then, in step S15 described above, roughly spherical particles of zirconia-supported nickel catalyst were prepared as catalyst 41, and the catalyst 41 was filled into each first cell 111a to obtain a membrane reactor 4. In addition, a glass sealing portion 21 was provided on the end surface 114 of the support 11 before attaching the seed crystals in step S12.

[0075] Next, simulating methanation in the membrane reactor 2, the membrane reactor 4 was repeatedly heated and cooled. Specifically, using a heating device such as an electric furnace, the membrane reactor 4 was heated from room temperature (e.g., 25°C) to 300°C and then cooled from 300°C to room temperature, and this cycle was repeated five times. The temperature rise rate and temperature fall rate were both 100°C / h. The performance of the separation membrane 12 of the membrane reactor 4 was evaluated before and after the five cycles of temperature rise and fall tests.

[0076] In the performance evaluation of the separation membrane 12, in order to evaluate the degree of defects (breakage) in the separation membrane 12, CF4 was supplied into the housing 22 in the above-mentioned membrane reactor 2, and the flow rate of CF4 permeating through the separation membrane 12 of the membrane reactor 4 (hereinafter also referred to as "CF4 permeation flow rate") was measured. Then, the ratio of the CF4 permeation flow rate after the temperature rise / fall test to the CF4 permeation flow rate before the temperature rise / fall test (hereinafter also referred to as "permeation flow rate ratio") was calculated.

[0077] When the permeation flow rate ratio is 1.0, there is no difference in the CF4 permeation performance of separation membrane 12 before and after the temperature rise / fall test, and it is clear that no damage to separation membrane 12 has occurred due to the difference in the thermal expansion coefficients, etc., between catalyst 41 and separation membrane composite 1. On the other hand, when the permeation flow rate ratio is greater than 1.0, there is a possibility that the separation membrane 12 has been damaged as described above, causing CF4 to leak from the damaged area, and this possibility increases as the permeation flow rate ratio increases.

[0078] The average particle size of catalyst 41 in Example 1 was 1.9 mm, and the catalyst particle size ratio (i.e., the ratio of the average particle size of catalyst 41 to the inner diameter of first cell 111a) was 0.95. The permeation flow rate ratio was 1.0, and it is believed that no damage to separation membrane 12 occurred due to differences in the thermal expansion coefficients, etc., between catalyst 41 and separation membrane composite 1.

[0079] In Examples 2 to 3 and Comparative Example 1, except that the average particle size of the catalyst 41 was varied, the membrane reactor 4 was obtained in the same manner as in Example 1, and the performance of the separation membrane 12 was evaluated in the same manner as in Example 1.

[0080] The average particle size of catalyst 41 in Example 2 was 1.7 mm, and the catalyst particle size ratio was 0.85. The permeation flow rate ratio was 1.1, and it is believed that there was almost no damage to separation membrane 12 due to differences in the thermal expansion coefficients, etc., between catalyst 41 and separation membrane composite 1.

[0081] The average particle size of catalyst 41 in Example 3 was 1.5 mm, and the catalyst particle size ratio was 0.75. The permeation flow rate ratio was 2.1, which suggests that damage to separation membrane 12 due to differences in the thermal expansion coefficients, etc., between catalyst 41 and separation membrane composite 1 was suppressed.

[0082] The average particle size of catalyst 41 in Comparative Example 1 was 1.1 mm, and the catalyst particle size ratio was 0.55. The permeation flow rate ratio was large at 50.0, and it is believed that the difference in the thermal expansion coefficients between catalyst 41 and separation membrane composite 1 caused damage to separation membrane 12, resulting in the leakage of CF4 from the damage.

[0083] Comparing Examples 1 to 3 with Comparative Example 1, from the viewpoint of suppressing damage to the separation membrane 12 due to differences in the thermal expansion coefficients, etc. between the catalyst 41 and the separation membrane composite 1 (for example, setting the permeation flow rate ratio to 10.0 or less), it is preferable that the catalyst particle size ratio be 0.75 or more.

[0084] Comparing Examples 1 to 3, from the viewpoint of further suppressing damage to the separation membrane 12 due to differences in the thermal expansion coefficients, etc. between the catalyst 41 and the separation membrane composite 1 (for example, setting the permeation flow rate ratio to 2.0 or less), it is preferable that the catalyst particle size ratio be 0.85 or more.

[0085] As described above, the membrane reactor 4 includes the separation membrane composite 1 and the catalyst 41. The separation membrane composite 1 includes the separation membrane 12 and the porous support 11. The catalyst 41 promotes chemical reactions of the raw materials. The support 11 is cylindrical and extends in the longitudinal direction. The support 11 is provided with membrane formation cells (i.e., first cells 111a) that are open at both longitudinal ends. The separation membrane 12 is disposed on the inner surface of the first cell 111a. The catalyst 41 is disposed within the first cell 111a of the separation membrane composite 1. The ratio of the average particle size of the catalyst 41 to the inner diameter of the first cell 111a (i.e., catalyst particle size ratio) is 0.75 or more and less than 1. This makes it possible to suppress damage to the separation membrane 12 caused by differences in the thermal expansion coefficients, etc., between the catalyst 41 and the separation membrane composite 1, as described above.

[0086] In the membrane reactor 4, not only when the first cells 111a are open at both longitudinal ends, but also when they are open at only one longitudinal end, damage to the separation membrane 12 due to differences in the thermal expansion coefficients between the catalyst 41 and the separation membrane composite 1 can be suppressed in a manner similar to that described above. That is, in the membrane reactor 4, as long as the first cells 111a are open at at least one longitudinal end, damage to the separation membrane 12 described above can be suppressed. However, from the viewpoint of further suppressing damage to the separation membrane 12 described above, it is preferable that the first cells 111a are open at both longitudinal ends.

[0087] As described above, the ratio of the average particle size of the catalyst 41 to the inner diameter of the first cells 111a is preferably 0.85 or more and less than 1. As a result, when stress occurs between particles of the catalyst 41 when the temperature of the membrane reactor 4 is increased or decreased, the direction of the stress approaches a direction parallel to the longitudinal direction of the first cells 111a. Therefore, damage to the separation membrane 12 caused by differences in the thermal expansion coefficients, etc., between the catalyst 41 and the separation membrane composite 1 can be further suppressed.

[0088] As described above, the inner diameter of the first cell 111a is preferably 0.2 mm or more and 10 mm or less. By setting the inner diameter of the first cell 111a to 0.2 mm or more, it is possible to prevent the amount of catalyst 41 held in the first cell 111a from becoming insufficient. Furthermore, by setting the inner diameter of the first cell 111a to 10 mm or less, it is possible to allow highly permeable substances in the reactants produced at the radial center of the first cell 111a to quickly reach the separation membrane 12 and be separated. In other words, it is possible to efficiently remove highly permeable substances from within the first cell 111a. As a result, it is possible to further promote the chemical reaction of the raw materials within the first cell 111a.

[0089] As described above, the cross section perpendicular to the longitudinal direction of the first cell 111a preferably has a circular shape. This allows the force to be dispersed approximately uniformly in the circumferential direction (i.e., the circumferential direction around the central axis extending in the longitudinal direction of the first cell 111a) even when the catalyst 41 applies force to the separation membrane 12 during temperature increases and decreases in the membrane reactor 4. In other words, the uniformity of the thermal stress applied to the separation membrane 12 in the circumferential direction can be improved. As a result, damage to the separation membrane 12 due to differences in the thermal expansion coefficients between the catalyst 41 and the separation membrane composite 1 can be further suppressed.

[0090] As described above, the separation membrane 12 is preferably a zeolite membrane. By forming the separation membrane 12 from zeolite crystals with uniform pore diameters, selective permeation of highly permeable substances can be suitably achieved. As a result, the highly permeable substances can be efficiently separated from the raw materials and the less permeable substances and removed from the first cell 111a. This further promotes the chemical reaction of the raw materials in the first cell 111a.

[0091] More preferably, the maximum number of ring members of the zeolite constituting the zeolite membrane is 8 or less. This allows for more favorable selective permeation of highly permeable substances with relatively small molecular diameters, such as HO, and as a result, the chemical reaction of the raw material in the first cell 111a can be further accelerated.

[0092] The membrane reactor 2 described above includes a membrane reactor 4 and a housing 22 that accommodates the membrane reactor 4. As described above, the membrane reactor 4 includes a separation membrane composite 1 and a catalyst 41. The separation membrane composite 1 includes a separation membrane 12 and a porous support 11. The catalyst 41 promotes a chemical reaction of the raw materials. The support 11 has a columnar shape extending in the longitudinal direction. The support 11 is provided with membrane formation cells (i.e., first cells 111a) that are open at both ends in the longitudinal direction. A separation membrane 12 is disposed on the inner surface of the first cell 111a. The catalyst 41 is disposed within the first cell 111a of the separation membrane composite 1. The ratio of the average particle size of the catalyst 41 to the inner diameter of the first cell 111a (i.e., catalyst particle size ratio) is 0.75 or more and less than 1. The method for operating the membrane reactor 2 includes the steps of supplying raw materials to the first cell 111a of the separation membrane composite 1, generating reactants by chemically reacting the raw materials in the presence of the catalyst 41 in an environment of 150°C or higher, and separating highly permeable substances from the reactants by passing them through the separation membrane 12 (step S22), and lowering the temperature of the membrane reactor 4 to 40°C or lower (step S23). As described above, the membrane reactor 4 can suppress damage to the separation membrane 12 caused by differences in the thermal expansion coefficients between the catalyst 41 and the separation membrane composite 1, and therefore the structure of the membrane reactor 4 is particularly suitable for the method for operating the membrane reactor 2 described above.

[0093] The above-described membrane reactor 4 and the method of operating the membrane reactor 2 can be modified in various ways.

[0094] For example, the inner diameter of the first cell 111a may be less than 0.2 mm and may be greater than 10 mm.

[0095] In the separation membrane composite 1, the maximum number of membered rings of the zeolite constituting the separation membrane 12, which is a zeolite membrane, may be greater than 8. Furthermore, the separation membrane 12 is not limited to a zeolite membrane and may be an inorganic membrane such as a silica membrane or a carbon membrane, or an organic membrane such as a polyimide membrane or a silicone membrane. In addition to the separation membrane 12, the separation membrane composite 1 may further include a functional membrane or a protective membrane laminated on the separation membrane 12. Such a functional membrane or protective membrane may be a zeolite membrane, an inorganic membrane other than a zeolite membrane, or an organic membrane.

[0096] The structure of the separation membrane composite 1 is not limited to the above example and may be modified in various ways. For example, the slits 117 penetrating the plurality of second cells 111b may be omitted. Furthermore, the plurality of cells 111 provided in the support 11 do not necessarily have to include the second cells 111b with both longitudinal ends plugged, and both ends of all the cells 111 may be open, and the separation membrane 12 may be provided on the inner surface of all the cells 111. In other words, all the cells 111 may be first cells 111a. Furthermore, the number of first cells 111a may be one.

[0097] A chemical reaction other than methanation may be carried out in the membrane reactor 2. The chemical reaction may be, for example, a reverse shift reaction, a methanol synthesis reaction, a Fischer-Tropsch synthesis reaction, or the like.

[0098] The above-described method for operating the membrane reactor 2 may be applied to the operation of a membrane reactor having a structure different from that of the above-described membrane reactor 2. The membrane reactor 4 may be used in a membrane reactor 2 operated by a method other than the above-described method for operating. Furthermore, the membrane reactor 4 may be used in a membrane reactor having a structure different from that of the above-described membrane reactor 2.

[0099] The configurations in the above-described embodiment and each modification may be combined as appropriate as long as they are not mutually contradictory.

[0100] While the invention has been particularly illustrated and described, it should be understood that the foregoing description is illustrative and not restrictive, and that numerous modifications and variations are possible without departing from the scope of the invention. [Industrial Applicability]

[0101] The membrane reactor of the present invention can be used as a membrane reaction device for producing various reactants from various raw materials through a chemical reaction in the presence of a catalyst. [Explanation of symbols]

[0102] 1 Separation membrane complex 2. Membrane reactor 4. Membrane reactor 11 Support 12 Separation membrane 22 Housing 41 Catalyst 111a Cell 1 S11~S15, S21~S23 steps

Claims

1. A membrane reactor comprising: a separation membrane composite including a separation membrane and a porous support; a catalyst that promotes a chemical reaction of the raw materials; Equipped with the support is a columnar member extending in the longitudinal direction, the support is provided with a membrane-forming cell that is open at at least one end in a longitudinal direction and has the separation membrane disposed on an inner surface thereof; the catalyst is disposed in the membrane-forming cell of the separation membrane composite; The ratio of the average particle diameter of the catalyst to the inner diameter of the film-forming cell is 0.75 or more and less than 1.

2. 2. The membrane reactor of claim 1, The ratio of the average particle diameter of the catalyst to the inner diameter of the film-forming cell is 0.85 or more and less than 1.

3. 3. The membrane reactor according to claim 1 or 2, The inner diameter of the film deposition cell is 0.2 mm or more and 10 mm or less.

4. 3. The membrane reactor according to claim 1 or 2, The cross section of the film deposition cell perpendicular to the longitudinal direction has a circular shape.

5. 3. The membrane reactor according to claim 1 or 2, The deposition cell is open at both ends in the longitudinal direction.

6. 3. The membrane reactor according to claim 1 or 2, The separation membrane is a zeolite membrane.

7. 7. The membrane reactor of claim 6, The maximum number of ring members of the zeolite constituting the zeolite membrane is 8 or less.

8. A method for operating a membrane reactor, comprising: The membrane reactor is a membrane reactor; a housing that accommodates the membrane reactor therein; Equipped with The membrane reactor comprises: a separation membrane composite including a separation membrane and a porous support; a catalyst that promotes a chemical reaction of the raw materials; Equipped with the support is a columnar member extending in the longitudinal direction, the support is provided with a membrane-forming cell that is open at at least one end in a longitudinal direction and has the separation membrane disposed on an inner surface thereof; the catalyst is disposed in the membrane-forming cell of the separation membrane composite; a ratio of an average particle diameter of the catalyst to an inner diameter of the film-forming cell is 0.75 or more and less than 1; The method for operating the membrane reactor comprises: a) supplying raw materials to the membrane-forming cell of the separation membrane composite, generating reactants by chemically reacting the raw materials in the presence of the catalyst in an environment of 150°C or higher, and separating highly permeable substances from the reactants by allowing them to permeate through the separation membrane; b) lowering the temperature of the membrane reactor to 40°C or less; Equipped with.

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