EP3393633A1

EP3393633A1 - Membrane assembly with bonding layer

Info

Publication number: EP3393633A1
Application number: EP16834016.4A
Authority: EP
Inventors: Markus HAYDN; Stephan Hummel; Marco Brandner
Original assignee: Plansee SE
Current assignee: Plansee SE
Priority date: 2015-12-21
Filing date: 2016-12-19
Publication date: 2018-10-31
Also published as: KR20180096642A; WO2017106886A1; US10751667B2; AT15049U1; US20190001275A1; CA3008027A1; JP2018538140A; CN108430611A

Abstract

The present invention relates to a membrane assembly for permeative separation of a fluid from fluid mixtures, comprising a porous, fluid-permeable, metal carrier substrate (2), a membrane (8) formed on the carrier substrate (2), that is selectively permeable for the fluid to be separated, a coupling part (6) that is made, at least superficially, from a fluid-tight metal material, the carrier substrate (2) being integrally connected along one edge section (3) to the coupling part (6), and a ceramic, fluid-permeable, porous first intermediate layer (10) formed between the carrier substrate (2) and the membrane (8). At least one ceramic bonding layer (14) is formed directly on the coupling part (6) and the integral connection (4), extending at least over the integral connection (4) and a neighbouring section of the coupling part (6). The first intermediate layer (10) extends on the bonding layer (14) and has a larger average pore size than the bonding layer (14).

Description

MEMBRANE ASSEMBLY WITH CONNECTION LAYER

The present invention relates to a membrane assembly for permeative

Separation of a fluid from fluid mixtures, in particular a gas

Gas mixtures, with a porous, fluid-permeable, in particular gas-permeable, metallic carrier substrate, a formed on the carrier substrate, selectively for the fluid to be separated (in particular gas) permeable membrane, at least superficially from a fluid-tight (in particular gas-tight) metallic material coupling part, wherein the carrier substrate along an edge portion of the same is materially connected to the coupling part, and with a formed between the carrier substrate and the membrane, ceramic, fluid-permeable (in particular gas-permeable), porous, first intermediate layer. The invention further relates to a method for producing such

Membrane assembly.

Membrane arrangements of this type are generally used for the selective separation of a fluid (liquid, gas) from fluid mixtures, in particular for the selective separation of a gas from gas mixtures, in particular for the separation of hydrogen from hydrogen-containing gas mixtures (eg from steam-reformed natural gas). In this case, a fluid, a gas or a mixture of a liquid and a gas is referred to as fluid. It is known that the property of certain materials, that they are only selectively for certain atoms or molecules (eg H ₂ ) permeable, exploited by being as a thin layer ("membrane"), such as a layer on a support or as intrinsically stable film for the subdivision of a fluid space (in particular gas space) for the fluid mixture of a fluid space (in particular gas space) for the fluid to be separated (in particular gas) are brought in. For example, if a gas mixture with a certain partial pressure of the gas to be separated, such as with a certain H ₂ -partial pressure, on one side of the membrane, the atoms / molecules of the gas to be separated endeavor to pass through the membrane to the other side, until on both sides of the same partial pressure of the gas to be separated consists of the membrane surface, a specific gas flow of the gas to be separated, in particular a specific

H ₂ gas flow, are assigned as a so-called performance parameter. It regularly applies that the thinner the membrane is and - at least for metallic Membranes - the higher the operating temperature, the higher the specific gas flow of the gas to be separated (eg H ₂ ). Largely appropriate

Requirements exist for the separation of liquids. For this reason, there is a need to use membranes as thin as possible in order to

desired gas flow to keep the system as small as possible and thus to reduce the system costs. Since thin membranes in the range of several μιη (microns) have a very low dimensional stability and rigidity, they are often as a layer on a porous, fluid-permeable (especially gas-permeable), rohrformigen or planar carrier substrate, which a fluid supply (in particular gas supply) to and / or fluid removal Guaranteed (in particular gas removal) of the membrane and provides a flat surface for application of the membrane is formed.

Metallic materials for the carrier substrate are distinguished from ceramic materials by low production costs and are relatively simple with an at least surface-fluid-tight (in particular gas-tight) and metallic coupling part, such as. by welding or soldering, connectable. Thus, via the coupling part, the integration of the membrane assembly in a module (with multiple membrane assemblies of this type) or more generally in a system within which the fluid separation (in particular gas separation) is carried out. Between the carrier substrate and the membrane, a ceramic, fluid-permeable (in particular gas-permeable), porous, first intermediate layer is provided, which serves to avoid diffusion effects and, in many cases, to gradually reduce the pore size from the metallic carrier substrate to the membrane.

The transition from the porous carrier substrate via the cohesive connection (eg weld seam) to the dense, metallic surface of the coupling part presents a high challenge in the application of the above-mentioned layers. In this transition region is a fluid-tight (in particular gas-tight) separation of the two fluid spaces (In particular gas spaces), at least as far as the other, in the fluid mixture (in particular gas mixture) in addition to the fluid to be separated

(especially gas) contained fluids (especially gases) are affected,

sure. However, due to the different material transitions, this transitional area represents the mechanical weak point and there are always spalling of the layers. A variant for producing such a dense transition region is in

No. 8,753,433 B2. There, the membrane is starting from the

Carrier substrate pulled over the coupling part and runs directly on this. The intermediate layer provided between the carrier substrate and the membrane extends beyond the connection region between the carrier substrate and the coupling part, but extends in the direction of the coupling part in front of the membrane. A

Membrane arrangement in which a dense layer in the transition region on a porous, ceramic support substrate and a gas-tight, ceramic

Ankopplungsteil extends and on which the membrane expires, is in the

JP 2014-046229 A.

The object of the present invention is a membrane assembly of the type specified above and a method for producing such a

To provide membrane arrangement in which the layer structure in the

Transition region between the carrier substrate and the coupling part remains connected over a long period of use areally with the respective substrate.

The object is achieved by a membrane arrangement according to claim 1 and by a method for producing a membrane arrangement according to claim 19. Advantageous developments of the invention are specified in the dependent claims.

According to the present invention, a membrane arrangement for the permeative separation of a fluid from fluid mixtures, in particular a gas

Gas mixtures (eg H ₂ from H ₂ containing gas mixtures) provided

(Fluid separation membrane arrangement, in particular gas separation membrane arrangement). In this case, the membrane arrangement has a porous, fluid-permeable (in particular gas-permeable), metallic carrier substrate, one on the carrier substrate

formed membrane (fluid separation membrane, in particular gas separation membrane) which is permeable selectively to the fluid to be separated (in particular gas separation membrane), a coupling part consisting at least superficially of a fluid-tight (in particular gas-tight) metallic material, wherein the carrier substrate is materially connected to the coupling part along an edge section thereof, and a formed between the carrier substrate and the membrane, ceramic, fluid-permeable (in particular gas-permeable), porous, first intermediate layer. At least along a partial section of the entire connecting length of the integral connection directly on the coupling part and the integral connection at least one, at least on the cohesive connection and an adjoining portion of the coupling part extending, ceramic

Connection layer formed. The first intermediate layer exits on or at the bonding layer and has a larger, average pore size than the

Connection layer on. The different layers are in one

An electron micrograph of a cross - section of a cross - section is obtained on the basis of the interfaces formed regularly between them, which in the case of

layered sintered layers are particularly pronounced, and the

Different pore size distinguishable from each other. As far as in this

Description and claims to "immediately" consecutive

Layers / components is referred to, the presence of intermediate layers / components is excluded. If, on the other hand, the term "direct" is not used, other layers / components may also be provided therebetween, as far as technically feasible In the case of range specifications, the specified limit values should be included in each case. "Fluid" is referred to a liquid, a gas or a mixture of a liquid and a gas. The fluid is preferably in each case a gas, or in the case of fluid mixtures, in each case gas mixtures. Insofar as reference is accordingly made to a "fluid-tight" or "fluid-permeable" property, according to a preferred embodiment, each is a "gas-tight" or

"Gas-permeable" property, although this is not explicitly mentioned each time.

The structure of the claimed membrane assembly is associated with several advantages, which will be explained below with reference to the operation of the individual components. The membrane is a thin, selectively for certain types of fluids, in particular gas types (especially for H ₂ ), permeable layer of a material referred to. In this case, the membrane (or its material) is selected according to the fluid to be separated, in particular gas (eg H ₂ ). The other fluids contained in the respective fluid mixture (in particular gas mixture) (in particular gases) may also be used in the design and material selection of the components

Include diaphragm assembly, for example, if a component for all of these fluids (in particular gases) of the fluid mixture (in particular

Gas mixture) must be formed fluid-tight (in particular gas-tight). The membrane may in principle be formed as an intrinsically stable foil as well as (at least) one layer on a carrier substrate. With regard to the highest possible

Performance parameters is used in the membrane assembly according to the invention a regularly planar design carrier substrate for the membrane in order to provide the membrane as a thin layer. The carrier substrate must be porous and fluid-permeable, depending on which side of the membrane

Carrier substrate is used (in tubular design, preferably on the inside of the membrane) to ensure the fluid supply to or fluid removal from the membrane. For the carrier substrate and thus also for the applied thereon membrane there are two common basic forms, namely a planar and a tubular basic shape, the focus more and more on the tubular or

tubular basic shape lies. Both metallic and ceramic materials are used for the carrier substrate, wherein the presently claimed, metallic carrier substrate is distinguished from ceramic carrier substrates in that it is easier to seal in the production, in the transition region to the coupling part and relatively easy with the coupling part, such as over a welding process, connectable. The production of such porous, fluid-permeable, metallic carrier substrates takes place, in particular, via a powder-metallurgical production method which comprises the steps of shaping (eg pressing) and sintering of metallic starting powders, whereby porous carrier substrates having a microstructure typical for powder metallurgy production are obtained. This microstructure is characterized in that the individual grains of the metal powder are recognizable, these individual grains are interconnected depending on the degree of sintering by more or less pronounced Sinterhälse (recognizable, for example, via an electron micrograph of a microsection). Porous, fluid-permeable, metallic carrier substrates, in particular such powder-metallurgically produced carrier substrates, however, have a relatively large pore size (in some cases up to 50 μm), which means sealing with a membrane which is typically only a few micrometers thick (thickness in the case of gas separation membranes, in particular in the range from 5-15 μιη) difficult. Particularly suitable materials for the carrier substrate are iron (Fe) -based (ie containing at least 50% by weight, in particular at least 70% by weight of Fe), a high chromium content (chromium: Cr). containing alloys (eg at least 16 wt.% Cr), to which further additives, such as yttrium oxide (Y ₂ 0 ₃ ) (to increase the oxidation resistance), titanium (Ti) and molybdenum (Mo) may be added, the proportion of these additives total preferably less than 3% by weight (cf., for example, the material designated as ITM from Plansee SE containing 71.2% by weight of Fe, 26% by weight of Cr and in total less than 3% by weight of Ti, Y ₂ 0 ₃ and Mo). Furthermore, at the high operating temperatures (typically operating temperatures for gas separation in the range of

450-900 ° C) Interdiffusionseffekte between the metallic carrier substrate and the (for the H ₂ separation regularly also metallic) membrane, which would lead over time to a degradation or destruction of the membrane. to

To avoid these disadvantages, at least one ceramic, fluid-permeable, porous intermediate layer (eg of 8YSZ, ie of zirconium oxide fully stabilized with 8 mol% yttrium oxide (Y ₂ O ₃ )) is used between the carrier substrate and the membrane. It suppresses interdiffusion effects between the carrier substrate and the membrane. Furthermore, via them, possibly also in stages (in particular via the

Application of several intermediate layers, i. via a "graded layer structure"), the pore size can be reduced to a few μπι, in particular to a suitable for the gas separation, average pore size in the range of 0.03-0.50 μιη, the first

Intermediate layer (and possibly further intermediate layers) and the membrane preferably extend over the entire, for the fluid separation (in particular

Gas separation) provided surface of the carrier substrate. In the case of a tubular design, this corresponds to the cylindrical outer surface (or possibly the cylindrical inner surface) of the carrier substrate, wherein optionally at least one axial edge region (for example for attaching a connection component or a sealing end) can be recessed. In the area of the layer structure, the sealing takes place (apart from the permeability for the fluid to be separated) through the membrane. For the completely fluid-tight supply and removal of the process fluids (in particular

Process gases), the layer structure is to be connected to corresponding connection lines of the system (for example reactor). For such a completely fluid-tight coupling of the layer structure to connection lines, an at least superficially fluid-tight metallic one is present immediately adjacent to the carrier substrate

Material used coupling part used. The coupling part can also fulfill other functions, such as merging or splitting several connecting lines. For this purpose, appropriately functionalized Sections formed on the coupling part and / or be connected to this. The carrier substrate is integrally connected to the coupling part along an edge section thereof (for example via a welded connection). The fluid-tight, metallic region of the coupling part is preferably provided on the same side as the membrane on the adjacent carrier substrate, in tubular form, in particular on the outside. In particular, it is in the

Coupling part to a metallic material in the solid material. In the case of one

tubular design is also the coupling part, at least in the on the

Support substrate adjacent region, tubular and the cohesive connection extends around the entire circumference of the adjacent components.

The transition region between the coupling part and the carrier substrate is at least for the other, in the fluid mixture in addition to the fluid to be separated (in particular gas) fluids or gases (hereinafter: "other fluids" in particular "other gases") fluid-tight (in particular gas-tight) to design. For this purpose, in particular the membrane itself, but alternatively also a layer which is fluid-tight for the other or all fluids of the fluid mixture, adjacent to the membrane or overlapping thereto, can be pulled out beyond the coupling part, in order to be fluid-tight on the coupling part (for the further or all Fluids of the fluid mixture) complete. To suppress the

Interdiffusion effects and porosity reduction is also the first

Intermediate layer in the direction of the coupling part at least to the end of the porous support substrate, preferably up to the adjacent region of the

Coupling part to carry out.

The invention is based on the finding that the flakes of the layers occurring in this transition region and leading to a failure of the membrane arrangement are due to the following causes: between the first intermediate layer and the fluid-tight, metallic material of the coupling part, which consists in particular of a metallic solid material (such as eg steel), there is only insufficient adhesion. This also applies to the field of

cohesive connection, which forms an unsteady transition and which is uneven in particular in the case of a weld. Furthermore lead different thermal Expansion coefficients of the materials used for the coupling part, the carrier substrate and the ceramic intermediate layer to stresses within the layer structure, in particular during the sintering of the layer structure or later in the use of the membrane assembly. As a result, if cracks develop within the first intermediate layer or flakes occur, they continue through the further layers of the layer structure and lead to failure of the layer

Membrane assembly. To the adhesion of the first intermediate layer in this

problematic transition area will increase, at least along one

Part of the entire connection length of the cohesive connection, preferably over the entire connection length, directly on the

Coupling and the cohesive connection at least one (in particular exactly one) applied ceramic bonding layer. With respect to the direction perpendicular to the cohesive connection, which in a tubular design corresponds to the axial direction, the connection layer extends at least over the cohesive connection and an adjacent section of the

Coupling part. It has a smaller, average pore size than the first intermediate layer, which terminates on the bonding layer on. As a result, a direct contact of the first intermediate layer with the problematic region of the material connection and the coupling part is reduced, preferably even completely eliminated. By the bonding layer below or immediately adjacent next to the first intermediate layer is applied directly to the coupling part and the integral connection, a significantly better adhesion is achieved due to the lower porosity. Also, this intermediate layer in the form of the bonding layer reduces the stress due to the different thermal expansion coefficients. In particular, in a sintering of the ceramic

Bonding layer formed between the finer ceramic particles of this bonding layer and the underlying metallic surface (in particular the cohesive connection and the coupling part) significantly more sintering necks than would be the case between the metallic surface and the first intermediate layer. This improves the adhesion of the bonding layer on the metallic surface. By two ceramic materials adhere relatively well, in particular can be sintered together well, the application of the first intermediate layer is not a problem and also leads to good adhesion. The occurrence of flaking, both during sintering in the context of Production as well as in later use, could thereby be avoided.

Preferably, the first intermediate layer extends in the direction of

Coupling part at least up to the end of the carrier substrate, possibly even to over the adjacent region of the coupling part to form a good support for the subsequent layers, especially if they have a finer grain structure than the first intermediate layer and the material of the carrier body , if necessary, could seep into the material of the carrier substrate. Preferably, the first intermediate layer runs on the bonding layer, i. such that in the direction perpendicular to the layer surface (corresponding to the radial direction in the case of a tubular basic shape), an overlapping region is formed between the attachment layer and the first intermediate layer (compare FIGS. 1, 3). In principle, however, it is also possible that there is no or only a very small overlapping area in that the first intermediate layer is not pulled over the bonding layer in the axial direction or only to a very small extent, as far as it is directly adjacent to the bonding layer

Adjacent layer adjacent (see Fig. 2).

According to a development, the average pore size of the bonding layer deviates by at least 0.10 μπι, in particular by at least 0.15 μπι, preferably even by at least 0.20 μηι, from the average pore size of the first intermediate layer. The consequent, significantly finer-grained structure of the bonding layer favors a particularly good adhesion of the same on the coupling part.

According to a development, the bonding layer is a sintered, ceramic layer. A ceramic, sintered layer is characterized by a typical microstructure, in which the individual ceramic grains are recognizable, these being interconnected by more or less pronounced sintering necks, depending on the degree of sintering (in the present, ceramic, sintered layers, the sintering necks can only be very weak). The typical

Microstructure is e.g. via an electron micrograph of a

Micrograph recognizable. Due to the small particle size and pore size, a multiplicity of sintered necks also form during the sintering process from the bonding layer to the underlying metallic surface, whereby the layer adhesion is improved. This is especially true in the areas of the material connection and the adjoining regions which tend to flake off Coupling part of advantage. According to a development is / are the first

Intermediate layer and possibly further, provided intermediate layers each (a) sintered, ceramic layer (s). Preferably, the individual, ceramic layers, in particular the bonding layer and the at least one

Intermediate layer, each via a wet-chemical process (e.g.

Wet powder coating, dip coating, etc.), in particular via dip coating in tubular basic form, applied and sintered in layers. Layer-by-layer sintering is e.g. in an electron micrograph of a micrograph of the sintered

Layer structure recognizable by the fact that the interfaces between the individual

Layers are more pronounced than in a common sintering of all, originally present in the green state layers, since in the latter production route, the interfaces between the layers due to diffusion effects blur more. According to a development, the attachment layer, starting from the cohesive connection, extends directly on the carrier substrate beyond a section of the carrier substrate adjoining the cohesive connection. The bonding layer extends from both sides of the bonded joint, i. to the side of the coupling part as well as to the side of the support substrate, the discontinuity in the region of the material connection is compensated on both sides by providing a substantially continuous transition and providing a uniform underlay for the first intermediate layer. This improves the adhesion of the layer structure and reduces the risk of cracking.

According to a further development, the connection layer extends, starting from the integral connection in the direction of the coupling part and / or in the direction of the carrier substrate, in each case over a length in the range from 0.2 to 3.0 cm. This length, which extends in the axial direction in a tubular or tubular design, is in the direction of the coupling part of the adjacent in this direction end of the cohesive connection (which usually itself over a certain

Connecting length extends, cf. 1 to 3) and in the direction of the carrier substrate are measured by the end of the material connection which adjoins in this direction Range of 0.2-2.0 cm, more preferably in the range of 0.3-1.0 cm. The further area and the narrower areas are selected on the one hand with regard to achieving a good layer adhesion on the one hand, and on the most effective utilization of the available space for the fluid separation (in particular gas separation) on the other hand.

According to a development, the bonding layer has a thickness in the range of 1 to 50 μm. In particular, the layer thickness is in the range of 2 to 20 μπι, more preferably in the range of 3 to 10 μπι. Within the wider area and especially within the narrower areas, on the one hand a good Schichmaftung to the underlying components as well as a good pad for the first

On the other hand, not too great unevenness is introduced by the application of the bonding layer. It should be noted that the layer thickness can vary, this being particularly true in the field of

cohesive connection is the case (in the region of a weld, for example, it may be thicker). Furthermore, it can become increasingly thinner towards the edge region and leak out and seep in the region of the carrier substrate. Therefore, a distance of 1 mm from the end of the integral connection in the direction of the coupling part is selected as the reference for the layer thickness (ie offset in each case 1 mm in the direction of the coupling part in FIGS. 1-3 from the region marked "d") This distance away in the direction of the coupling part, the bonding layer preferably has a substantially constant layer thickness, until it then thins towards its end.Generally, in layer thickness information, information pore size and in terms of the particle size in each case to these parameters in the ready State, ie, to be sintered layers on the sintered state.

According to a development, the bonding layer is porous and fluid-permeable, in particular gas-permeable. As a result, fluid transport, in particular gas transport, to and from the membrane through the attachment layer is also made possible in the region of the attachment layer. The porosity of the bonding layer is preferably at least 20%, wherein the determination of the porosity due to the small layer thickness and due to the most angular shape of the individual

Ceramic particles is subject to a relatively large measurement error. However, a porous and fluid-permeable bonding layer is not mandatory. In particular, she can also have no pores, which would correspond to the below explained embodiment of an average pore length of 0 μπι. According to a development, the bonding layer has an average pore size in the range of 0-0.50 μm, in particular in the range of 0.01-0.30 μm, more preferably in the range of

0.03 - 0.25 μη, on. In particular, the pore size distribution is the

Bonding layer in the range of 0.01 - 10.00 μιη. According to a development, the bonding layer has an average particle size in the range of 0.01 to 1, 00 μm, in particular in the range of 0.01 to 0.75 μm, more preferably in the range of

0.03 - 0.50 μηι on. In particular, the particle size distribution is the

Bonding layer in the range of 0.01 - 25.00 μηι. The other areas for the average pore and particle sizes and the corresponding size distributions and in particular the narrower areas are on the one hand to achieve a good adhesion of the bonding layer on the ground, on the other hand to make a good transition to the expiring, first intermediate layer, which has a larger, average pore size and possibly has a larger average particle size selected. The layer thickness of the first intermediate layer is according to a development in the range between 5-120 μπι, in particular in the range between 10-100 μιη, more preferably in the range between 20-80 μπι. The layer thickness data for the first and below-mentioned second intermediate layer relate to the region of the carrier substrate with a substantially constant layer thickness profile, while in the transition region to the coupling part due to unevenness and layer thickness variations may occur.

The pore size or pore length of a single pore is determined as follows: the area of the respective pore in the micrograph is measured and, subsequently, its equivalent diameter, which would result for a circular shape of the same area size, is determined. Accordingly, the particle size is determined. to

Determining the pore sizes and particle sizes becomes a perpendicular to the

made cross-section through the membrane arrangement and investigated a correspondingly prepared micrograph in the scanning electron microscope (SEM). The analysis is carried out by threshold value of the different gray levels from the respective REM-BSE image (BSE: back-scattered electrons;

backscattered electrons). The brightness and contrast of the

REM BSE image adjusted so that the pores and particles in the image look good recognizable and distinguishable from each other. With the slider, the

Depending on the grayscale differentiation between pores and particles, a suitable grayscale value is selected as the threshold value. In order to determine the mean pore size, the pore size of all the pores of a representative region of the relevant layer previously selected in the micrograph is measured, and then its mean value is formed. Accordingly, the determination of the mean

Particle size. For the individual particles to be measured in each case, its geometric outline is decisive and not the grain boundaries of optionally a plurality of grains connected to a particle, each having a different, crystallographic orientation. Only the pores or particles that are completely within the selected range are included in the evaluation. The porosity of a layer can be determined in the micrograph (SEM-BSE image) by determining the area fraction of the pores within a selected area relative to the total area of that selected area, including the areas of the pores only partially within the selected area be involved. In the present case, the program Imagic Image Access

(Version: 1 1 Release 12.1) with the analysis module "Particle Analysis" used.

According to a development, the first intermediate layer has a smaller average pore size than the carrier substrate. According to a development, the first

Intermediate layer an average pore size in the range of 0.20 to 2.00 μιη, in particular in the range of 0.31 to 1, 20 μιη, more preferably in the range of 0.31 to 0.80 μηι on. In particular, the pore size distribution of the first intermediate layer is in the range of 0.01-25.0 μπι. According to a development, the first

Interlayer an average particle size in the range of 0.70 to 3.50 μιη, in particular in the range of 0.76 to 2.50 μπι, more preferably in the range of

0.80 - 1.80 μιη, on. In particular, the particle size distribution is the first

Interlayer in the range of 0.01 - 100.00 μιη. The porosity of the first intermediate layer is preferably at least 20%, wherein the determination of the porosity due to the small layer thickness and due to the most angular shape of the individual ceramic particles is associated with a relatively large measurement error. By the mentioned features is taken in each case as well as in

Combination starting from the carrier substrate, a gradual reduction of achieved mean pore size up to the membrane.

According to a development, a ceramic, fluid-permeable, in particular gas-permeable, porous, second intermediate layer, which has a smaller average pore size than the first, extends between the first intermediate layer and the membrane

Intermediate layer has. The providence of the second interlayer is

In particular advantageous in gas separation membrane arrangements, in the case of the separation of liquids can be dispensed with in many cases, the second intermediate layer. According to a development, the second intermediate layer has an average pore size in the range of 0.03 to 0.50 μm, in particular in the range of

0.03 - 0.30 μηι, more preferably in the range of 0.03 - 0.25 μπι on. According to a development, the second intermediate layer has an average particle size in the range of 0.01-1.00 μπι, in particular in the range of 0.01-0.75 μιη, more preferably in the range of 0.03-0.50 μηι on. In the particle size distribution and the

Pore size distribution, the areas specified for the bonding layer are preferred. The layer thickness of the second intermediate layer is according to a

Training in the range between 5 - 75 μπι, in particular in the range between 5 - 50 μπι, more preferably in the range between 10 - 25 μπι. By providing the second intermediate layer with a reduced pore size and preferably a reduced particle size, a sufficiently smooth surface for applying the membrane is provided and also a diffusion barrier is provided.

Preferably, the same starting material and the same sintering step are used for the second intermediate layer as for the bonding layer, so that it is similar in composition and its microstructure of the bonding layer. According to a development, the second intermediate layer extends in the direction of

Coupling part beyond the first intermediate layer addition. In particular, it may leak on the bonding layer or alternatively on the coupling part on which it adheres as well as the bonding layer due to the comparable properties. In this way, a sufficiently smooth surface for the application of the membrane is continuously provided up to the coupling part. According to a development, the membrane extends in the direction of the coupling part beyond the bonding layer and the at least one intermediate layer and runs directly on the coupling part. As a result, in the transition region, at least one of the further fluids of the fluid mixture (in particular of the other fluids) is used Gases of the gas mixture) achieved fluid-tight arrangement. In general, the second intermediate layer can adjoin the membrane directly. Alternatively, however, it is also possible to provide one or more further, ceramic, fluid-permeable (in particular gas-permeable), porous intermediate layer (s) between the second intermediate layer and the membrane, in which case preferably the average pore size of this further intermediate layer (s) proceeding from the second intermediate layer decreases even further towards the membrane.

According to a development, the materials of the attachment layer and the at least one intermediate layer are selected from the group of the following materials:

a. zirconia stabilized with yttria (Y ₂ O ₃ ) (ZrO ₂ )

b. zirconia stabilized with calcium oxide (CaO) (ZrO ₂ ),

c. magnesia (MgO) stabilized zirconia (Zr0 ₂ ), and

d. Alumina (A1 ₂ 0 ₃ ).

Preferably a yttria stabilized zirconia (YSZ short), in particular a with 8 mol% yttria (Y ₂ 0 _3), fully stabilized zirconia (8YSZ short). According to a development, the connection layer and the at least one

Intermediate layer of one and the same material (or composition) formed. As a result, comparable, thermal expansion coefficients are achieved and a cost-effective production possible. Preferably, these are YSZ, in particular 8YSZ. The individual layers, in particular the

Bonding layer and the second intermediate layer on the one hand and the first

Intermediate layer on the other hand, but may differ in their Milaostruktur, for example, in the average pore size, the average particle size and the

Porosity. Instead of fully stabilized zirconia (e.g., adding typically 8 mol% yttria on Y2O3 as a stabilizer), a partially stabilized

Zirconium oxide (eg addition of typically 3 mol% yttrium oxide with Y ₂ 0 ₃ as a stabilizer) are used. Other stabilizers of zirconia also come ceria (Ce0 _2), scandia (Sc0 ₃₎ or ytterbium oxide (Y b0 ₃₎ in question.

According to a development, the carrier substrate and the coupling part are each tubular or tubular. Its cross-section is preferably circular with a constant diameter along the axial direction. Alternatively, but also a otherwise closed cross-section, such as an oval cross-section, and be provided along the axial direction aufweitender cross-section. The cohesive connection can in principle be formed by an integral design of the coupling part and of the carrier substrate, by a solder connection and by a welded connection. According to a development, the cohesive connection is formed by a welded connection, which preferably extends in the case of a tubular basic shape around the entire circumference of the respective, tubular edge section. A welded joint is inexpensive and process reliable to produce. Due to the porosity of the carrier substrate, a depression typically forms in the region of the welded connection.

For hydrogen separation, the materials used for the membrane are basically pure metals which have a certain permeability to hydrogen but which are a barrier to other atoms / molecules. With a view to avoiding formation of an oxide layer which would impair this selective permeability, for hydrogen separation (H ₂ ) it is preferable to use noble metals, in particular palladium, palladium-containing alloys (especially more than 50% by weight of palladium), for example palladium - Vanadium, palladium-gold, palladium-silver, palladium-copper, palladium-ruthenium or palladium-containing composite membranes, such as with the layer sequence palladium, vanadium, palladium, used. According to a development, the membrane is accordingly off

Palladium or a palladium-based metallic material (e.g., alloy, composite, etc.). The Pd content of such membranes is in particular at least 50% by weight, preferably at least 80% by weight. Further, it is preferred that the bonding layer and / or the at least one intermediate layer of

Yttria (Y ₂ 0 ₃ ) stabilized zirconia (Zr0 ₂ ), in particular from 8YSZ, is formed / are. Furthermore, it is preferred that the carrier substrate and the coupling part are each formed from iron-based materials. These features of

various components are advantageous per se, in particular they show advantageous effects in combination.

The present invention further relates to a method for producing a

Membrane arrangement for the permeative separation of a fluid from fluid mixtures, in particular a gas from gas mixtures, especially for the separation of H ₂ from H ₂ comprising gas mixtures comprising a porous, fiuiddurchlässiges (in particular gas-permeable), metallic carrier substrate and an at least on the surface of a fluid-tight (in particular gas-tight), existing metallic coupling part, wherein the carrier substrate along an edge portion of the same is integrally connected to the coupling part. The method has the following steps:

a. Applying at least one ceramic bonding layer directly on the cohesive connection and directly on an adjoining portion of the coupling part along at least a portion of the entire connection length of the cohesive connection;

b. Successive application of at least one ceramic, fluid-permeable

(in particular gas-permeable), porous intermediate layer on the carrier substrate (and the overlapping region of the bonding layer), wherein the directly applied to the carrier substrate intermediate layer on or on the

Tie layer leaking and a larger, average pore size than the

Has bonding layer, and

a selectively permeable to the fluid to be separated (in particular gas) permeable membrane on the at least one intermediate layer.

By the method according to the invention substantially the same advantages as in the membrane arrangement according to the invention described above are achieved.

The further developments and variants described above can also be realized correspondingly in the method according to the invention while achieving corresponding advantages.

In the connection layer and the at least one intermediate layer is the

Applying, in particular, that the layer containing an organic binder and ceramic particles is applied by a wet-chemical method and then sintered, and only then the subsequent layer (possibly in

corresponding manner) is applied.

Further advantages and advantages of the invention will become apparent from the following description of exemplary embodiments with reference to the accompanying figures. From the figures show:

Fig. 1: a schematic cross-sectional view of an inventive

Membrane arrangement in the axial direction according to a first

Embodiment of the invention;

Fig. 2: a schematic cross-sectional view of an inventive

Membrane arrangement in the axial direction according to a second

Embodiment of the invention;

3 shows a schematic cross-sectional view of a device according to the invention

Membrane arrangement in the axial direction according to a third embodiment of the invention;

Fig. 4: pore size distribution of the bonding layer according to a

Embodiment of the invention;

5: particle size distribution of the bonding layer according to a

Embodiment of the invention;

FIG. 6: Pore size distribution of the first intermediate layer according to FIG

Embodiment of the invention; and

FIG. 7: Particle size distribution of the first intermediate layer according to FIG

Embodiment of the invention. 1-3 are different, differing in construction embodiments of a membrane assembly for the permeative separation of a gas to be separated (eg H ₂ ) from a gas mixture (eg steam reformed natural gas containing CH ₄ , H ₂ 0, C0 ₂ , CO, H ₂ , etc.), with only the

Transition region is shown by the carrier substrate to the coupling part. In Fig. 1, a tubular, porous, gas-permeable, metallic support substrate 2 (e.g., ITM) is disposed along the (circular) edge portion 3 thereof

integral connection 4, which in the present case is formed by a welded joint, is connected to a tubular coupling part 6 formed in the solid material of a metal (for example steel). The weld of the cohesive connection 4 forms a circumferential recess which extends in the axial direction a over a length d. Over the region of the carrier substrate (apart from a possibly recessed edge region at the distal end, not shown) of the carrier substrate

Support substrate 2) extends a selectively permeable to the gas to be separated membrane 8 (eg of Pd). Between the carrier substrate 2 and the membrane 8 extends a first ceramic, gas-permeable, porous intermediate layer 10 (eg of sintered 8YSZ) and a second ceramic, gas-permeable, porous

Interlayer 12 (e.g., sintered 8YSZ). In a region spaced from the material connection 4, the first intermediate layer 10 is formed directly adjacent to the carrier substrate 2 and has a smaller average pore size than the carrier substrate 2. In this area is the second

Intermediate layer 12 immediately adjacent to the first intermediate layer 10 and formed on its other side immediately adjacent to the membrane 8. It has a smaller average pore size than the first intermediate layer 10. In the region of the integral connection 4, a ceramic bonding layer 14 (eg of sintered 8YSZ) is formed directly on the coupling part 6 and the integral connection 4, which extends at least over the integral connection 4 and an adjoining section of the coupling part 6, wherein the first intermediate layer 10 expires on the bonding layer 14. In the first

In addition to the schematic representation, in the region of the carrier substrate 2 it can also be infiltrated into the pores by the bonding layer 14, starting from the cohesive connection 4 and also via an adjoining section of the carrier substrate 2. The

In the present case, the bonding layer 14 is porous and permeable to gas and extends over the entire (circular) connection length of the bonded joint

Connection 4 (as well as the adjacent areas of the carrier substrate 2 and the

Coupling part 6). The second intermediate layer 12 extends beyond the first intermediate layer 10 in the direction of the coupling part 6, so that a sufficiently smooth underlay for the membrane 8 is provided. The second intermediate layer 12 likewise runs out on the bonding layer 14, with the bonding layer 14 also being reduced by virtue of its reduced middle position relative to the first intermediate layer 10

Pore length provides a sufficiently smooth surface for the membrane 8. The membrane 8 extends in the direction of the coupling part 6 over the

Tie layer 14 (and the two intermediate layers 10 and 12) and runs out directly on the coupling part 6, to which it produces a gas-tight connection for the gas to be separated (eg H ₂ ).

In the following description of the second and third embodiments shown in FIGS. 2 and 3, the same reference numerals will be used for the same components used. In the present case, only the differences compared to the first embodiment will be discussed. In the second embodiment (FIG. 2), the bonding layer 14 'extends only over the integral connection 4 and an adjoining section of the coupling part 6 (over the whole of FIG

Connection length of the cohesive connection 4). Until the beginning of the

cohesive connection 4, the first intermediate layer 10 thus extends directly on the carrier substrate 2, on which it adheres relatively well. In the third embodiment (FIG. 3), the coupling part 6 "is made of a porous,

gas-permeable base material, in particular of the same material as the carrier substrate 2 (for example ITM), and has a gas-tight surface region 16 only on its outside surface. The gas-tight surface region 16 can be produced, for example, by applying a coating or a sealing compound or by superficial melting of the porous base material of the coupling part 6 "

Embodiment in that the second intermediate layer 12 "over the

Tie layer 14 also extends and on the coupling part 6 "expires.

In the following, an example for the production of an inventive

Membrane arrangement described. A support substrate in the form of a porous tube made of ITM with an outer diameter of 6 mm, a length of 200 mm, a porosity of about 40% and an average pore size of <50 μπι is formed at one axial end thereof with a solid material made of steel , tubular

Coupling part with the same outer diameter welded by laser welding. In order to ensure a homogenization of the weld transition, the resulting component is annealed under a hydrogen atmosphere at a temperature of 1200 ° C. Subsequently, the surface in the area of the welded joint is sandblasted to obtain a more uniform surface. Next, the bonding layer is applied in the area of the weld joint.

For this purpose, from two 8YSZ powders of different particle size, in particular a powder with a d80 value of about 2 μηι (and with a d50 value of about 1 μπι) and a very fine powder having a particle size (crystallite size) of approx 25 nm

(Nanometer), one suitable for a wet-chemical coating process

Suspension, for example with the addition of dispersant, solvent (eg BCA [2- (2-butoxyethoxy) ethyl] acetate, available from Merck KGaA Darmstadt) and binder. The bonding layer is brushed all over on the weld joint and on the adjacent areas of the carrier substrate and the coupling part. The weld is located in the middle of the bonding layer extending around the entire circumference and the layer width extends in each case 1 cm from the respective end of the weld in the direction of the coupling part and in the direction of the carrier substrate. The obtained component is subsequently sintered under a hydrogen atmosphere at a temperature of 1200 ^° C., whereby the organic constituents are burned out, a sintering of the ceramic layer takes place and the porous, sintered, ceramic bonding layer is obtained. A typical pore size distribution and particle size distribution of a bonding layer produced in this way is shown in FIGS. 4 and 5. In particular, the pore size distribution is in the range of 0.03 to 5.72 μηι (with an average pore size of 0.13 μιτι), as shown in FIG. 4 can be seen (with a few pores having a larger diameter are no longer shown), and the

Particle size distribution is in the range of 0.03 - 18.87 μιη (with an average particle size of 0.24 μηι), as shown in FIG. 5 can be seen (with a few particles are no longer shown with a larger diameter). In a next step, a suspension of 8YSZ powder is again prepared for the first intermediate layer, wherein the information given above to the bonding layer apply mutatis mutandis, except that an overall coarser 8YSZ powder is used and a slightly higher viscosity of the suspension than in the bonding layer is set. In particular, as a ceramic powder exclusively

8YSZ powder with a d80 value of about 2 μιη (and with a d50 value of about 1 μπι) used. The first intermediate layer is formed by dip-coating, i. by immersing the tubular component in the suspension, applied and runs on the bonding layer. Subsequently, the resulting component is under

Sintered hydrogen atmosphere at a temperature of 1,300 ° C, whereby the organic constituents are burned out, a sintering of the ceramic layer takes place and the porous, sintered, ceramic first intermediate layer is obtained. A typical pore size distribution and particle size distribution of a first intermediate layer produced in this way is shown in FIGS. 6 and 7. In particular, the pore size distribution is in the range of 0.08 to 12.87 μηι (with an average pore size of 0.55 μηι), as shown in FIG. 6 can be seen (with a few pores are no longer shown with larger diameter), and the Particle size distribution is in the range of 0.08 to 61.37 μπι (with an average particle size of 1.27 μηι), as with reference to FIG. 7 can be seen (with a few particles with a larger diameter are no longer shown). For the second intermediate layer to be applied subsequently, the same suspension as for the bonding layer is applied and applied by dip-coating. The second intermediate layer completely covers the first intermediate layer. Subsequently, the obtained component is sintered under a hydrogen atmosphere at a temperature of 1,200 ° C, whereby the organic components are burned out, takes place sintering of the ceramic layer and the porous, sintered, ceramic second intermediate layer is obtained. Subsequently, a Pd membrane is applied via a sputtering process. It completely covers the second intermediate layer as well as the underlying bonding layer and first intermediate layer.

Finally, a further Pd layer is applied to the Pd sputter layer via a galvanic process in order to seal the latter and to achieve the required gas tightness.

The present invention is not limited to those shown in the figures

Limited embodiments. In particular, the cohesive connection is not necessarily realized as a welded joint. For example, it can also be designed as a solder joint or adhesive bond. Furthermore, the

Coupling member and the support substrate also be formed integrally or monolithically and the cohesive connection forms the transition between the

gas-permeable carrier substrate and the at least superficially gas-tight

Coupling part. For example, in the third embodiment (FIG. 3), a monolithic design of the carrier substrate and the coupling part would also be possible. Furthermore, the structure described is suitable not only for the H ₂ separation, but also for the separation of other gases (eg C0 ₂ , 0 ₂ , etc.). Further alternative membrane can be used, such as microporous ceramic membranes (A1 ₂ 0 _3, Zr0 _2, Si0 _2, Ti0 _2, zeolites, etc.) or dense, proton-conducting ceramics (SrCe0 _3- 8, BaCe0 _3- 8, etc. ). For the separation of liquids (eg alcohols from water-containing liquid mixtures, wastewater treatment, etc.), nanoporous membranes of carbon, zeolites, etc. can be used as membranes, among other things.

Claims

Patent claims

Membrane arrangement for the permeative separation of a fluid

Fluid mixtures comprising

a porous, fluid-permeable, metallic carrier substrate (2),

a membrane (8) formed on the carrier substrate (2) and selectively permeable to the fluid to be separated,

a coupling part (6; 6") consisting at least on the surface of a fluid-tight, metallic material, the carrier substrate

(2) along an edge section

(3) the same is cohesively connected to the coupling part (6; 6"),

a ceramic, fluid-permeable, porous first intermediate layer (10) formed between the carrier substrate (2) and the membrane (8),

characterized in that

at least along a portion of the entire connecting length of the cohesive connection (4) directly on the coupling part (6; 6") and the cohesive connection (4) at least one, at least via the cohesive connection (4) and an adjacent section of the coupling part ( 6; 6"), ceramic connecting layer (14; 14 ') is formed and that the first intermediate layer (10) on or on the

The connecting layer (14; 14') runs out and has a larger average pore size than the connecting layer (14; 14').

Membrane arrangement according to claim 1, characterized in that the average pore size of the connecting layer (14; 14') deviates from the average pore size of the first intermediate layer (10) by at least 0.10 μπι.

Membrane arrangement according to claim 1 or 2, characterized in that the connecting layer (14; 14') and/or the first intermediate layer (10) is/are a sintered, ceramic layer.

4. Membrane arrangement according to one of the preceding claims, characterized in that the connecting layer (14), starting from the cohesive connection (4), extends directly on the carrier substrate (2) up to a section of the material adjoining the cohesive connection (4).

Carrier substrate (2) extends.

5. Membrane arrangement according to one of the preceding claims, characterized

characterized in that the connecting layer (14; 14"), starting from the cohesive connection (4), extends in the direction of the coupling part (6; 6") and/or in the direction of the carrier substrate (2) over a length in the range of 0 inclusive. 2 cm up to and including 3.0 cm.

6. Membrane arrangement according to one of the preceding claims, characterized

characterized in that the connecting layer (14; 14") has a thickness in the range from 1 μm to 50 μm inclusive.

7. Membrane arrangement according to one of the preceding claims, characterized

characterized in that the connecting layer (14; 14") is porous and fluid-permeable.

8. Membrane arrangement according to one of the preceding claims, characterized

characterized in that the connecting layer (14; 14") has an average pore size in the range from 0 to 0.50 μm inclusive.

9. Membrane arrangement according to one of the preceding claims, characterized

characterized in that the first intermediate layer (10) has a smaller average pore size than the carrier substrate (2).

10. Membrane arrangement according to one of the preceding claims, characterized

characterized in that the first intermediate layer (10) has an average pore size in the range from 0.20 μm to 2.00 μm inclusive.

1 1. Membrane arrangement according to one of the preceding claims, characterized in that between the first intermediate layer (10) and the membrane (8) there is a ceramic, fluid-permeable, porous, second

Intermediate layer (12; 12") extends, which has a smaller average pore size than the first intermediate layer (10).

12. Membrane arrangement according to claim 11, characterized in that the second intermediate layer (12; 12") extends beyond the first intermediate layer (10) in the direction of the coupling part (6; 6").

13. Membrane arrangement according to one of the preceding claims, characterized

characterized in that the membrane (8) moves in the direction of

Coupling part (6; 6") extends beyond the connecting layer (14; 14') and the at least one intermediate layer (10, 12; 12") and ends directly on the coupling part (6; 6").

14. Membrane arrangement according to one of the preceding claims, characterized

characterized in that the materials of the connecting layer (14; 14 ') and the at least one intermediate layer (10, 12; 12") from the group of

The following materials are selected:

a. zirconium oxide (Zr0 ₂ ) stabilized with yttrium oxide (Y ₂ 0 ₃ ),

b. zirconium oxide (Zr0 ₂ ) stabilized with calcium oxide (CaO),

c. zirconium oxide (Zr0 ₂ ) stabilized with magnesium oxide (MgO), and d. Aluminum oxide (A1 ₂ 0 ₃ ).

15. Membrane arrangement according to one of the preceding claims, characterized

characterized in that the connecting layer (14; 14') and the at least one intermediate layer (10, 12; 12") are formed from one and the same material.

16. Membrane arrangement according to one of the preceding claims, characterized

characterized in that the carrier substrate (2) and the coupling part (6; 6") are each tubular. Membrane arrangement according to one of the preceding claims, characterized in that the cohesive connection (4) through a

Welded connection is formed. 18. Membrane arrangement according to one of the preceding claims, characterized

marked,

that the membrane (8) is made of palladium or a palladium-based,

metallic material is formed,

that the connection layer (14; 14 ') and / or the at least one

Intermediate layer (10, 12; 12") made of yttrium oxide (Y ₂ 0 ₃ ) stabilized

Zirconium oxide (Zr0 ₂ ) is/are formed and

that the carrier substrate (2) and the coupling part (6; 6") each

Iron-based materials are formed. 19. Process for producing a membrane arrangement for the permeative separation of a fluid from fluid mixtures

a porous, fluid-permeable, metallic carrier substrate (2) and

has a coupling part (6; 6") consisting at least on the surface of a fluid-tight, metallic material,

wherein the carrier substrate (2) is cohesively connected to the coupling part (6; 6") along an edge section (3).

characterized by the following steps: a. Applying at least one ceramic bonding layer (14; 14') directly to the cohesive connection (4) and directly to an adjacent section of the coupling part (6; 6") along at least a portion of the entire connection length of the cohesive connection (4); Gradual application

at least one ceramic, fluid-permeable, porous intermediate layer (10, 12; 12") onto the carrier substrate (2), the intermediate layer (10) applied directly to the carrier substrate (2) ending on or at the connecting layer (14; 14') and has a larger average pore size than the connecting layer (14; 14 '), and

a membrane (8) which is selectively permeable to the fluid to be separated onto the at least one intermediate layer (10, 12; 12").