Structured membrane unit, production method and setup method

Abstract

The invention relates to a membrane unit (10) for a membrane reactor, comprising a membrane (12) and a support structure (14) for supporting the membrane (12). The support structure (14) is structured such that cavities (18) adjoining the membrane (12) are provided for receiving catalyst material (20). In this way, loose bulk catalyst material can be introduced into the cavities and catalyst material located in the cavities can be removed from the cavities. As a result, it is possible to exchange the catalyst material independently of the membrane.

Description

[0001] Research Center Jülich GmbH

[0002] Structured membrane unit, manufacturing process and setup process

[0003] Description

[0004] The invention relates to a membrane unit for a membrane reactor, a method for producing such a membrane unit and a method for equipping a membrane unit.

[0005] Membrane reactors enable catalytic reactions while simultaneously separating and / or feeding substances through the membrane. This allows the thermodynamics of the reaction to be influenced, for example, to increase yield or influence selectivity. Membrane reactors have a wide range of applications, for example, in the chemical industry or in fuel cells and electrolyzers.

[0006] Membrane reactors are known in which the catalyst material is a component of the membrane. This can be achieved, for example, by impregnating the membrane material with catalytically active species, depositing prefabricated catalytic nanoparticles, immobilizing molecular catalysts, or using intrinsically catalytically active membrane materials.

[0007] On the other hand, membrane reactors are known in which the catalyst material is integrated into the support structure.

[0008] Fluidized-bed membrane reactors are also known in which the catalyst material is not fixed but is located in a moving layer within the membrane area. Loose catalyst beds are also known.

[0009] It is the object of the invention to provide a further developed membrane unit as well as a method for producing and a method for equipping such a unit.

[0010] This object is achieved by the membrane unit according to claim 1 and by the manufacturing method and the setup method according to the independent claims. Advantageous embodiments are specified in the subclaims. This object is achieved by a membrane unit for a membrane reactor. The membrane unit comprises a membrane and a support structure for supporting the membrane. The support structure is structured in such a way that cavities are present for accommodating catalyst material. The cavities are directly adjacent to the membrane or are separated from the membrane by one or more intermediate layers.

[0011] The inventive solution has the effect that a loose bed of catalyst material can be filled into the cavities, and that catalyst material present in the cavities can be removed from the cavities. This makes it possible to replace the catalyst material, for example, in the event of irreversible deactivation, while the membrane and its support structure remain intact. On the other hand, if the membrane is irreversibly deactivated, it can also be replaced along with the support structure, and the catalyst material can continue to be used. Thus, both the catalyst and the membrane can be regenerated, recycled, or replaced separately.

[0012] In some processes, for example, the catalyst material cokes over time. The invention makes it possible to replace the catalyst material and refill and reuse the membrane. This significantly extends the membrane's service life and reduces costs and technical complexity. Typically, the membrane or the combination of membrane and reactor are the cost drivers in membrane reactors for catalytic reactions, while the catalyst accounts for only a minor share of the costs. Therefore, particularly significant savings can be achieved in this area of ​​technology.

[0013] A further advantage is the position of the catalyst material directly adjacent to the membrane or the intermediate layer. This ensures close contact and short distances improve mass transport. Mass transport limitations are minimized. Compared to a loose catalyst bed on a membrane, the catalyst is fixed perpendicular to the direction of expansion of the membrane. This minimizes the susceptibility to errors. Unplanned transport of the catalyst up to and including its discharge is prevented. The membrane can be constructed from multiple layers. The catalyst material is arranged adjacent to the outermost layer of the membrane or the intermediate layer. Compared to membranes with immobilized catalyst, the amount of catalyst is not limited by the surface area of ​​the membrane, since a larger amount of catalyst material per unit area of ​​the membrane can be provided in the cavities.Competition between permeation through the membrane and catalyst productivity is avoided. The catalyst loading can be specifically adjusted or optimized for different operating points.

[0014] A membrane reactor is a reactor containing a membrane. The membrane is used for separation. In particular, the membrane reactor is designed to carry out a physical, chemical, and / or biochemical reaction. In particular, the membrane reactor is a fixed-bed reactor. In addition to chemical and biological membrane reactors, the solution according to the invention can also be used for any type of membrane separation process, resulting in comparable advantages.

[0015] The membrane is, in particular, a selectively gas-permeable membrane, i.e., a membrane that only allows a specific gas or group of gases to pass through. The membrane is typically flat. In particular, the membrane is planar. In one embodiment, however, the membrane can also be curved, for example, tubular. The membrane can be a metallic membrane or a ceramic membrane. The membrane can have an area greater than 1 mm 2 and / or less than 1 m 2 A variety of membranes can be used in a membrane reactor. The membrane can be constructed from one or more layers.

[0016] The support structure serves to mechanically support the membrane. In this way, the mechanical forces acting on the membrane are absorbed or dissipated by the support structure. The support structure thus serves as burst protection. In one embodiment, the support structure is porous. This allows mass transport to occur not only through the cavities but also through the support structure itself. This improves mass transport.

[0017] The support structure is structured. This means that the support structure is not a solid component that essentially lies against the membrane over its entire surface, but rather that the support structure has shaped elements that form cavities between one another. In particular, there is a regular sequence of shaped elements. In one embodiment, a maximum of 70% of the surface of the membrane is in contact with the support structure. The remaining 30% then falls into cavities. In one embodiment, a maximum of 50% or a maximum of 30% of the surface of the membrane is in contact with the support structure. In one embodiment, a maximum of 10% of the surface of the membrane is in contact with the support structure.

[0018] The support structure is designed to provide the cavities. The support structure encloses the cavities in at least one spatial direction. Pores of a porous medium are not cavities within the meaning of the invention. In other words, the support structure is macroscopically structured. Typically, the cavities are deliberately introduced. Preferably, the cavities are regularly arranged. Preferably, the cavities have the same size and / or shape. In this way, defined conditions for the operation of the membrane reactor can be created.

[0019] In particular, the cavities are accessible. This means that the membrane unit is designed such that the cavities are open at least on one side against which the membrane or an intermediate layer is not in contact. In this way, catalyst material can be introduced and / or removed. This does not preclude the possibility that closable openings for the cavities can be present in the membrane reactor into which the membrane unit is inserted or in a holder for the membrane unit. Such openings, when open, can allow the catalyst material to be introduced into and / or removed from one or more cavities and / or, when closed, can prevent unplanned penetration of catalyst material into one or more cavities and / or unplanned removal of catalyst material from one or more cavities.

[0020] In particular, the catalyst material is present as a loose bed. The cavities are designed such that the catalyst material can be introduced into the cavities and removed from the cavities. For example, the catalyst material can be in spherical, cylindrical, or tablet form. A desired grain size distribution can be used. The size and shape of the cavities can be specifically adapted to the catalyst material to be used. In one embodiment, connecting channels are present that connect several cavities to one another. In this way, a hierarchical structure can be created. Catalyst material from several cavities can be removed or added simultaneously via the connecting channels. Connecting channels typically do not have direct contact with the membrane. Connecting channels typically have a larger cross-section than the cavities adjacent to the membrane or intermediate layer.

[0021] One, two or more intermediate layers can be present between the membrane and the support structure. Typically, at most one intermediate layer is present. An intermediate layer can be porous or dense. An intermediate layer can, for example, serve as a protective layer. For example, an intermediate layer can serve as a diffusion barrier, especially when the membrane and support structure are made of different materials. An intermediate layer can, for example, have the same or a similar thickness to the membrane. For example, the thickness of the intermediate layer can be between 20% and 500% of the thickness of the membrane, in particular between 50% and 200% of the thickness of the membrane, and preferably between 70% and 150% of the thickness of the membrane. Taken together, all intermediate layers present typically have a smaller thickness than the support structure. An intermediate layer preferably has a similar thickness to the membrane or is thinner than the membrane.If the intermediate layers are too thick or there are too many intermediate layers, the mass transport and / or the support effect of the support structure can be impaired.

[0022] In one embodiment of the membrane unit, the cavities are accessible. This makes it possible to remove catalyst material and / or fill them with catalyst material without an additional work step. In particular, the cavities are accessible on a side facing away from the membrane. Alternatively, the cavities can also be accessible from the side. Accessible means that the cavities have an opening to an environment. In particular, the opening to the environment has an opening width that is at least 20%, in particular at least 50%, preferably at least 80% or at least 90% of the width of the respective cavity in the region adjacent to the membrane or the intermediate layer. This makes it particularly easy to remove catalyst material and / or fill it with catalyst material. In a further embodiment, the support structure comprises webs. In particular, the support structure is constructed from webs.In particular, the webs are arranged at a distance from one another. In other words, the webs typically do not touch each other, at least in the area of ​​the membrane. The webs typically form elongated cavities between each other in the area of ​​the membrane. However, it is possible for the webs to contact each other in an area facing away from the membrane and / or to jointly form a continuous component. The webs can have straight walls.

[0023] In one embodiment, the webs are aligned at an angle a between 80° and 100°, preferably between 85° and 95°, in particular approximately 90°, to the membrane surface. The angle a is measured between a central axis of the respective web, viewed in cross-section, and the surface of the membrane facing the web. In this way, the cavities also extend at this angle to the membrane. The production of such a membrane unit is particularly simple.

[0024] In one embodiment, the webs are aligned at an angle a between 20° and 80° to the membrane surface. This facilitates filling and removing catalyst material. For example, the angle a is between 30° and 60°. This has been shown to make filling and removing catalyst material particularly easy.

[0025] In one embodiment, the walls of the webs are straight. The shape of the walls of the webs particularly applies to the walls that run along the main direction of extension of the webs. In particular, there are straight cavities between the walls. In particular, the walls of the webs are flat.

[0026] In one embodiment, the walls of the webs are corrugated. In another embodiment, the walls of the webs are rough. Corrugation and suitable roughness can further improve the filling with catalyst material and the removal of catalyst material.

[0027] In one embodiment, the support structure is designed such that an extension of the cavities measured parallel to the membrane increases with increasing distance from the membrane. The cavities therefore taper towards the membrane. In this way, filling with catalyst material and removing catalyst material is further simplified. In particular, shaped elements of the support structure, between which the cavities are located, are shaped such that a distance between adjacent shaped elements increases with increasing distance from the membrane. The shaped elements can be separate elements such as webs. Alternatively, the shaped elements can be regions of a particularly contiguous component. For example, cylindrical or conical cavities that extend as far as the membrane can be present in a contiguous part of the support structure. In this case, the walls of the support structure that delimit these cavities can be the shaped elements.

[0028] In a further embodiment, cavities are provided that are surrounded by the material of the support structure over their entire circumference. The cavities are, in particular, cylindrical or conical, at least in sections. Such a design allows the catalyst material to be fixed in all directions transverse to the membrane. This prevents unwanted transport or discharge of the catalyst material.

[0029] In particular, the membrane is located at one end of the cavities. In particular, the other end of the cavities is open. The cavities can be cylindrical in shape, at least in sections, and / or conical in shape, at least in sections. Different regions of the cavities can have different shapes. The different regions can, in particular, be different sections along the longitudinal extent of the cavities. The cavities can be completely cylindrical or conical in shape.

[0030] The cylindrical cavities can be circular. Alternatively, other cross-sections are possible, such as square, honeycomb, or hexagonal cross-sections. The conical cavities can also have the aforementioned cross-sections. In conical cavities, the cross-section of the respective cavity tapers in one direction.

[0031] Viewed perpendicular to the membrane, the cavities are typically surrounded by support structure material along their entire circumference. The cavities are typically not surrounded by support structure material at the longitudinal ends of the cavities, but are open.

[0032] In particular, the cavities are arranged regularly. The cavities can be arranged, for example, in rows and / or columns. Adjacent cavities in each column and / or each row can have the same distances from one another. This makes it possible, for example, to achieve a cubically dense arrangement. In another embodiment, the cavities in adjacent rows and / or columns are arranged offset. Here, too, adjacent cavities in each column and / or each row can have the same distances from one another. This makes it possible, for example, to achieve a hexagonally dense arrangement.

[0033] In one embodiment, the support structure comprises walls with a wall thickness of at least 10 pm, in particular at least 30 pm and / or at most 1 cm, in particular at most 1000 pm, between which cavities are located.

[0034] The cavities are separated from each other by walls of the support structure with the specified wall thickness. This refers in particular to the wall thickness in a position immediately adjacent to the membrane or the intermediate layer. This range has proven suitable for most applications.

[0035] The walls can be in the form of webs. For example, the walls can have a constant wall thickness. Alternatively, the walls can be arranged in a continuous layer of the support structure, separating individual cavities from each other. In this case, wall thickness refers to the minimum wall thickness between two adjacent cavities.

[0036] Alternatively or additionally, the cavities have an extension > 50 pm and / or < 1 cm, in exceptional cases even up to several cm. In particular, this refers to the extension of the cavities in a position directly adjacent to the membrane or the intermediate layer. The extension can be the minimum extension. Smaller cavities are difficult to fill with catalyst material, and catalyst material is difficult to remove. On the other hand, cavities that are too large lead to low mechanical stability of the membrane unit, since the membrane is then unsupported over large stretches. In order to operate safely below the burst protection limit, the extension of the cavities must be limited according to requirements. The actual size of the cavities depends on the respective specifications and framework conditions, e.g. the transmembrane pressure.

[0037] In a further embodiment, the membrane unit comprises the catalyst material located in the cavities. The catalyst material is in particular a powder or granulate with a defined grain size distribution and / or with a defined shape. The following can apply to the grain size or size distribution of the catalyst: the diameter d of the catalyst grains is smaller than the diameter of the cavity and / or the diameter d is at least 20 pm, in particular at least 50 pm and / or at most 1 cm, in particular at most 1000 pm. The diameter d of the catalyst grains is in particular smaller than or equal to the diameter Dh of the cavity. In particular, this refers to the cross-section of the cavity at its thinnest point. The ratio d / Dh is preferably at least 0.01 and / or at most 0.9.

[0038] In one embodiment, the membrane comprises a material or the membrane is made of a material which is selected from the group of cation-conducting oxides, in particular the group of proton-conducting oxides, in particular from the group comprising BaZr x Ce y Y z O3 (BZCY) with x+y+z = 1, BaZr x Y y O3 (BZY) with x+y = 1 and SrZr x Ce y Y z O3 (SZCY) with x+y+z = 1 .

[0039] In one embodiment, the membrane comprises a material or the membrane is made of a material which is selected from the group of anion-conducting oxides, in particular the group of oxygen ion-conducting oxides, in particular from the group comprising Zr0.92Y0.08O2 (8YSZ), Ceo.9Gdo.1O (CGO or GDC).

[0040] In one embodiment, the membrane comprises a material or the membrane is made of a material which is selected from the group of mixed ion-electron-conducting oxides, in particular from the group comprising

[0041] Lae- x WOi2-ö (LWO), with 0.2 < x < 0.8; ö denotes the deviation from the nominal amount of oxygen and depends on the composition and the ambient conditions, La6- x Wi. y Mon y Oi2-ö (LWO-Mo) with y < 0.4, SrTi x Fei- x O3 (STF) with 0.5 < x < 1), BaO.5SrO.5Coo.8FeO.2O3-6 (BSCF), and LaO.6SrO.4Coo.2FeO.8O3-6 (LSCF). In one embodiment, the membrane comprises a material or the membrane is made of a material selected from the group of hydrogen-conducting metals, in particular Pd, Pd-Ag, or other ceramic-supported Pd-containing membranes.

[0042] A further aspect of the invention is a method for producing a membrane unit according to the invention. The support structure is manufactured using an additive manufacturing process. All features, advantages, and properties of the membrane unit described above apply analogously to the manufacturing process, and vice versa.

[0043] The additive manufacturing process is particularly selected from 3D screen printing, material extrusion, free-jet binder deposition, free-jet material deposition and bath-based photopolymerization. In 3D screen printing, material is pressed layer by layer through a printing form to build up the part to be manufactured layer by layer. In material extrusion, material is selectively deposited through an opening to build up the part to be manufactured layer by layer. In binder jetting, powdered starting material is combined with a binder at selected positions to create workpieces. In material jetting, material is applied in the form of droplets and then cured, in particular by UV light or heat. In bath-based photopolymerizationIn vat photopolymerisation, liquid photopolymer is selectively cured in a container by light-activated polymerisation.

[0044] Additive manufacturing processes allow the cavities according to the invention to be produced particularly easily and cost-effectively. Cavities can thus be created in a targeted manner. Directed channels, uniformly arranged cavities, and thus membrane units can be produced whose behavior is predictable and modelable. Furthermore, hierarchical structures, for example, with connecting channels, can be manufactured. Structures can be produced whose geometry is structured over several orders of magnitude, for example, from the pm range to the cm range. Particularly advantageous structures can be produced that could not be produced using conventional processes, such as inclined webs, undercuts, or cavities. In particular, a support structure green body is provided using an additive manufacturing process. Sintering can then take place to produce the support structure.

[0045] In one embodiment, a pore former is used to produce a porous layer. In particular, a porous support structure is produced in this way.

[0046] In one embodiment, the membrane is manufactured using an additive manufacturing process or using film casting. The additive manufacturing process is selected, in particular, from 3D screen printing, material extrusion, free-jet binder deposition, free-jet material deposition, and bath-based photopolymerization.

[0047] In tape casting, a particularly ceramic powder, typically together with a dispersant, is dispersed in a solvent to produce a slurry. The slurry is then poured onto a casting base, dried, cut to size if necessary, and sintered. In particular, sequential tape casting can be used, in which two or more layers are cast one on top of the other.

[0048] Alternatively or additionally, multiple layers and / or layer composites can be bonded together through heat treatment and / or lamination. This can also create a material bond.

[0049] With sequential tape casting, the membrane and the support structure can be manufactured using two different slurries. A pore former can be used to create a porous layer, for example, in the area of ​​the support structure.

[0050] In particular, a membrane green body is created using an additive manufacturing process or by tape casting. Sintering can then be performed to produce the support structure.

[0051] In one embodiment, the membrane green body and the support structure green body are provided in a single step, in particular by means of an additive manufacturing process. In another embodiment, the process comprises the provision of a membrane green body, the provision of a support structure green body, and the joint sintering of the membrane green body and the support structure green body to produce a composite of membrane and support structure.

[0052] It is irrelevant whether the membrane and support structure are first produced from the respective green bodies and then bonded together, whether the green bodies are first bonded together and then the membrane and support structure are produced from them, or whether these processes occur at least partially simultaneously. Sintering bonds the membrane and support structure together, creating a one-piece composite component.

[0053] The membrane green body can be produced using an additive manufacturing process or tape casting. The support structure green body can be produced using an additive manufacturing process.

[0054] In one embodiment, the green bodies are manufactured separately and then bonded together. In another embodiment, the green bodies are manufactured together. The composite is preferably a material-to-material bond.

[0055] The process makes it possible to produce the membrane unit according to the invention simply and cost-effectively.

[0056] A further aspect of the invention is a membrane assembly comprising a membrane unit according to the invention and a holder for holding the membrane unit. The holder can be designed as a frame for receiving the membrane unit. The membrane unit is fastened to the holder, for example by means of solder such as glass solder. In particular, at least the support structure of the membrane unit is mechanically fastened to the holder. Preferably, the membrane is also fastened to the holder. Typically, the membrane is sealed from the holder, in particular with the glass solder. All features, advantages, and properties of the membrane unit described above apply analogously to the membrane assembly and vice versa. A further aspect of the invention is a fixed-bed membrane reactor comprising at least one membrane unit according to the invention.All features, advantages and properties of the membrane unit described above apply analogously to the fixed bed membrane reactor and vice versa.

[0057] A further aspect of the invention is a method for equipping a membrane unit according to the invention, in which a catalyst material to be replaced is removed from the cavities and / or catalyst material is introduced into the cavities. All features, advantages, and properties of the membrane unit described above apply analogously to the upgrade method, and vice versa. In other words, the method can be a method for introducing the catalyst material and / or a method for removing the catalyst material.

[0058] The catalyst material can be introduced by trickling, i.e., by gravity, brushing, blowing, for example, fluidized in a fluid, which can be, for example, a liquid, a gas, a liquid-gas mixture, or a gas mixture, and / or by pressure blast. The catalyst material can be removed from the cavity by pouring, i.e., by gravity, brushing, blowing, for example, fluidized in a gas or gas mixture, and / or by pressure blast. These methods can be combined as desired.

[0059] The process may also comprise operating the membrane unit, preferably in a membrane reactor. In this case, the process may be referred to as a process for operating a membrane unit.

[0060] In one embodiment, a membrane unit is joined, for example, using solder such as glass solder. For example, the membrane unit is joined to another membrane unit or a holder.

[0061] The invention is explained in more detail below using examples.

[0062] They show:

[0063] Figure 1: a section through a membrane unit from a first side;

[0064] Figure 2: a section through a membrane unit from a second side;

[0065] Figure 3: a view of a membrane unit from the support structure; Figure 4: a schematic representation of an exchange of catalyst material;

[0066] Figure 5: a section through another membrane unit;

[0067] Figure 6: a membrane unit with catalyst material;

[0068] Figure 7: removal of catalyst material from a membrane unit;

[0069] Figure 8: further filling of a membrane unit with catalyst material;

[0070] Figure 9: a section through another membrane unit;

[0071] Figure 10: a section through another membrane unit;

[0072] Figure 11 : a section through another membrane unit;

[0073] Figure 12: a view of another membrane unit from the support structure;

[0074] Figure 13: a view of another membrane unit from the support structure;

[0075] Figure 14: a view of another membrane unit from the support structure; and

[0076] Figure 15: a view of another membrane unit from the support structure.

[0077] Figures 1 and 2 show sections of a membrane unit 10 according to the invention from two different sides. On the upper side is the membrane 12, which has a thickness of, for example, 50 μm. Below this is a support structure 14, which mechanically supports the membrane 12. The support structure 14 is structured such that cavities 18 are present that border the membrane 12. A catalyst material 20 can be arranged in these cavities 18. In addition to the embodiments shown here, one or more intermediate layers (not shown here) can also be present between the membrane 12 and the support structure 14.

[0078] The support structure 14 is composed of webs 15. The wall 16 of the webs 15 has a width c of 30 μm and a depth b of 300 μm. The webs 15 are spaced apart by a distance a of 50 μm. The depth b of the walls 16 corresponds to the depth of the cavities 18. The webs 15 are arranged at an angle a of 90° with respect to the membrane 12.

[0079] The figures are purely schematic and the sizes and proportions of the individual components are not to scale.

[0080] Figure 3 shows a membrane unit 10, particularly from Figures 1 and 2, with the orientation of the support structure 14. The webs 15 are visible. Between the webs 15, the membrane 12 is visible through the cavities 18. Figure 4 shows a similar illustration, in which a granulated catalyst material 20 is schematically arranged in the upper cavity 18 shown. To the right of the membrane unit 10 shown, a single grain or a single particle of the catalyst material 20 with the diameter d is shown. Arrow 25 indicates an introduction of catalyst material 20; arrow 26 indicates a discharge of catalyst material 20. For example, a pressure surge occurs, with which the catalyst material 20 contained in the cavity 18, for example irreversibly deactivated, is fluidized and in this way is transported, in particular transversely to the membrane 12, through the cavity 18 and out of it in the longitudinal direction of the cavity 18.Alternatively or additionally, a fresh catalyst material 20 can be introduced into the cavity 18 in the same way. By filling the fresh catalyst material 20, the contained catalyst material 20 can also be displaced and thus removed from the cavity 18. Alternatively or additionally, the catalyst material 20 can be introduced and / or removed by brushing in or out.

[0081] Figures 5 to 8 show a further embodiment of a membrane unit 10 in a sectional view. Here, the membrane 12 is oriented vertically. The support structure 14 is also composed of webs 15, the walls 16 of which are characterized by the same parameters as described above with reference to Figures 2 and 3. However, the angle α in this exemplary embodiment is less than 80° and in particular between 40° and 60°, preferably between 50° and 55°. The cavities 18 also have this angle α to the membrane 12. Figure 6 shows a similar view in which a granulated catalyst material 20 is schematically arranged in the upper cavity 18 shown. The support structure 18 can be located on the sweep side or on the reactor side of the membrane 12.

[0082] The choice of angle α described above significantly simplifies the filling and removal of the catalyst material 20, as shown by way of example in Figures 7 and 8. Figure 7 shows the filling of catalyst material 20 by gravity and / or in a fluidized state. The inclined webs 15 allow the catalyst material 20 to be easily transported to the membrane 12 by gravity. Figure 8 shows the generation of a pressure pulse 27, for example from a gas or gas mixture, for introducing and / or removing catalyst material 20. Figure 9 shows a further embodiment of a membrane unit 10. In addition to the support structure 14, which is arranged on one side of the membrane 12, a support structure 14 is now also arranged on the opposite side of the membrane 12. The side shown on the left is the sweep side and the side shown on the right is the reactor side.Accordingly, the parameters characterizing the support structure 14 are provided with the indices S and R. In one embodiment, both support structures 14 are constructed similarly or identically. For example, the same number of webs 15, webs 15 with the same width Cs, CR, the same depth bs, bR, the same spacing αs, βR, and / or with the same angle α, β can be provided. Individual parameters such as the angle α, β or the depth bs, bR can also be selected differently.

[0083] Figure 10 shows an embodiment of a membrane unit 10 which is similar to the design in Figure 2, to the description of which reference is made here. However, instead of straight walls, the webs 15 have corrugated and / or rough walls 16. The webs in this embodiment are also referred to as lamellae. In addition to the features and properties discussed above in relation to Figure 2, which can apply analogously to the embodiment shown here, the roughness of the wall 16 and the periodicity can be selected within desired ranges. A mean roughness value between 0.05 pm and 300 pm, in particular between 2 pm and 100 pm, has proven particularly advantageous. A periodicity or groove spacing between 1 pm and 300 pm, in particular between 5 pm and 100 pm, has also proven particularly advantageous.

[0084] Figure 11 shows another embodiment of a membrane unit 10, which is also based on Figure 2, to which reference is hereby made. The webs 15 of Figure 1 have parallel walls 16. In contrast, the webs 15 according to Figure 11 are shaped such that the cavities 18 taper conically towards the membrane 12. A distance ai between the individual webs 15 in the area immediately adjacent to the membrane 12 is smaller than a distance a2 between the webs 15 at the end of the webs 15 facing away from the membrane 12. In other words, the extent of the cavities 18 transverse to the membrane 12 becomes larger with increasing distance from the membrane 12. Thus, when filling with catalyst material and when removing catalyst material, a funnel effect occurs which facilitates filling. In the exemplary embodiment shown here, the walls 16 of the webs 15 also have a linear profile, for example. This is advantageous for flow reasons.

[0085] Further embodiments of a membrane unit 10 are shown in Figures 12 to 15. Here, as in Figure 3, the view is directed towards the support structure 14 and the membrane 12 located behind it. In contrast to the previously described embodiments, the support structure is not constructed from webs 15, but rather forms a continuous layer with openings. The openings form the cavities 18 adjacent to the membrane 12 for receiving catalyst material 20. The cavities 18 are thus surrounded over their entire circumference by the material of the support structure 14. The membrane 12 is visible through the openings. The openings can have different shapes, such as a square or rectangular shape according to Figure 12, a circular shape according to Figure 13, or a hexagonal or honeycomb shape according to Figure 14.The openings can be arranged, for example, in a checkerboard pattern, as shown in Figures 12 to 14. Alternatively, the openings can be arranged offset, as shown in Figure 15. The openings can be cylindrical or conical, for example, analogous to Figure 11, with a size that decreases toward the membrane. The openings can be arranged perpendicular or obliquely to the membrane 12.

[0086] In one embodiment, a composite of membrane green body and support structure green body is produced using an additive manufacturing process, for example, 3D screen printing, free-jet binder deposition, free-jet material deposition, or bath-based photopolymerization, and then sintered. The production of the two green bodies can be carried out in a single step.

[0087] In another embodiment, a membrane green body is manufactured using one additive manufacturing process, such as 3D screen printing, and the support structure green body is manufactured using another additive manufacturing process, such as material extrusion, and then sintered. Sintering typically occurs simultaneously to produce a one-piece component.

[0088] In another embodiment, the membrane and the support structure are made of different materials and then bonded together by heat application. In another embodiment, the membrane green body is produced by tape casting, and the support body green body is manufactured using an additive manufacturing process.

[0089] List of reference symbols

[0090] Membrane unit 10 Membrane 12 Support structure 14 Web 15 Wall 16 Cavity 18 Catalyst material 20 Inlet 25 Outlet 26 Pressure surge 27 Distance a, as, a R , ai, 82 depth b, b s , b R Width C, Cs, CR Diameter d, d R Angles a, ß

Claims

Claims 1. Membrane unit (10) for a membrane reactor, comprising a membrane (12) and a support structure (14) for supporting the membrane (12), characterized in that the support structure (14) is structured such that cavities (18) are present for receiving catalyst material (20), wherein the cavities (18) are directly adjacent to the membrane (12) or are separated from the membrane by one or more intermediate layers.

2. Membrane unit (10) according to the preceding claim, characterized in that the cavities (18) are accessible on a side of the support structure (14) facing away from the membrane (12).

3. Membrane unit (10) according to one of the preceding claims, characterized in that the support structure (14) is constructed from webs (15).

4. Membrane unit (10) according to claim 3, characterized in that the webs (15) are aligned at an angle a between 80° and 100°, in particular between 85° and 95°, to the membrane surface.

5. Membrane unit (10) according to claim 3, characterized in that the webs (15) are aligned at an angle a between 20° and 80° to the membrane surface.

6. Membrane unit (10) according to one of claims 3 to 5, characterized in that walls (16) of the webs (15) run straight.

7. Membrane unit (10) according to one of claims 3 to 5, characterized in that walls (16) of the webs (15) are corrugated.

8. Membrane unit (10) according to one of the preceding claims, characterized in that an extension of the cavities (18) measured parallel to the membrane (12) becomes larger with increasing distance from the membrane (12).

9. Membrane unit (10) according to one of the preceding claims, characterized in that cylindrical or conical cavities (18) are present which are surrounded over their entire circumference by the material of the support structure (14).

10. Membrane unit (10) according to one of the preceding claims, characterized in that the support structure (14) comprises walls (16) with a wall thickness between 10 pm and 1 cm, between which cavities (18) are located.

11. Membrane unit (10) according to one of the preceding claims, characterized in that the membrane unit (10) comprises the catalyst material (20) located in the cavities (18).

12. A method for producing a membrane unit (10) according to one of claims 1 to 11, characterized in that the support structure (14) is produced using an additive manufacturing process.

13. Method according to the preceding claim, characterized in that the membrane (12) is produced using an additive manufacturing process or using film casting.

14. Method according to one of the two preceding claims, characterized in that the method comprises: - Provision of a membrane green body, - Provision of a support structure green body, - Joint sintering of the membrane green body and the support structure green body to produce a composite of membrane (12) and support structure (14).

15. A method for equipping a membrane unit (10) according to one of claims 1 to 11, wherein a catalyst material (20) to be replaced is removed from the cavities (18) and / or catalyst material (20) is introduced into the cavities (18).

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