Patent Application
20250163619
The present invention relates to a method for producing a two-layer noble metal mesh on a flat-bed knitting machine which comprises a first and a second needle bed. The method comprises providing at least one noble-metal-containing wire and knitting the noble metal mesh. The first and second layers of the noble metal mesh are knitted simultaneously on the first and second needle bed, and a support mesh is knitted on the first and second needle bed using a support thread. An abutting edge of the support mesh is thus connected to the two layers of the noble metal mesh via connecting knit stitches, and knitting is carried out across the two needle beds in the knitting rows containing the connection.
The heterogeneous noble-metal-catalyzed oxidation of ammonia (NH3) to nitric acid (HNO3, Ostwald process) or the production of hydrogen cyanide (HCN, Andrussow process) is of great importance due to the central relevance of the products for the chemical industry. The catalyst systems used for this purpose are typically, in the form of gas-permeable fabrics, incorporated into the reaction zone of a flow reactor in a plane perpendicular to the flow direction of the fresh gas. Collecting or catchment systems for recovering evaporated catalytically active components are also frequently based on such mesh-like structures. Usually, a plurality of meshes are expediently arranged one behind the other and combined to form a catalyst mesh stack. The individual meshes consist of fine noble metal wires which predominantly contain platinum (Pt), palladium (Pd), rhodium (Rh) or alloys of these metals. In particular, catchment meshes may also contain further constituents, for example nickel.
A number of methods for producing such knitted goods are known, for example weaving, warp-knitting and weft-knitting. Weaving and warp-knitting are particularly suitable for the production of rectangular mesh webs which have a homogeneous material distribution and structure. They offer little flexibility in terms of the shape and material variability of the products to be manufactured. In an additional method step, the meshes have to be cut, from the manufactured webs, to a size and shape suitable for the reactors, resulting in offcuts which comprise noble metal components. In addition, the machines used require long set-up times and a high material input.
In comparison, weft-knitting offers greater flexibility: the knitting patterns, wires (both in terms of thickness and material), needles and tension of the wire can be used to vary both the weight per unit area as well as the structure, elasticity and strength of the obtainable knitted fabrics. Another advantage is the significantly shorter machine set-up times. It is also possible to use different materials in one knitted fabric; in so-called intarsia knitting, for example, different regions are made from different yarns or wires. In principle, the length of a knitted fabric is not limited, but, in the case of flat-bed knitting machines, the maximum width is determined by the width of the needle beds.
Flat-bed knitting machines or circular knitting machines can be used for knitting. In circular knitting machines, the needles are arranged in a circular needle bed and the thread or wire is supplied in a circular motion. These machines are primarily used for the production of tubular knitted goods. On flat-bed knitting machines, however, the shape and size of the knitted fabric can be varied. The latter can also comprise more than one needle bed, between which the yarn or wire is guided back and forth during production by means of thread guides.
The use of two needle beds allows a single-layer or two-layer knitted fabric to be produced. In principle, a single-layer knitted fabric can be created in two ways: in one, only one needle bed is worked on, i.e., only stitches are formed on one of the needle beds and knitted together. In the other, stitches created on the first needle bed can be knitted with stitches created on the second needle bed, i.e., the thread is guided back and forth between the two needle beds within a right and/or wrong side row. Accordingly, a two-layer knitted fabric is created when knitting is done in parallel on both needle beds and the stitches created on the first needle row are not knitted or only selectively knitted with the stitches created on the second needle bed via the edge stitches. With this production method, two single-layer knitted fabrics or layers can thus also be produced in parallel on the first and second needle bed.
The knitting of noble metal meshes is described in EP 0544710 A1. EP 3795728 A1 uses flat-bed knitting machines for this purpose. It is described that separate layers, produced on different needle beds, can be interconnected by means of a connecting knitting row on one side of the two knitting surfaces. This allows knitted surfaces to be produced that have larger widths than was previously possible.
EP 0364153 A1 describes the use of an additional noble-metal-free thread when knitting a noble metal mesh, which increases the process stability. The additional thread is knitted in parallel with the noble metal and can be removed from the produced homogeneous knitted fabric, consisting of noble metal material and thread material, after the knitting process if required. In EP 3779005 A1, this method was developed further to the effect that the additional thread and the noble metal are not knitted in parallel, but simultaneously. This means that noble-metal-free regions can be preserved in the finished knitted fabric, which leads to a reduction in the amount of noble metal used.
However, it has been shown that the simultaneous knitting of noble-metal-containing and noble-metal-free wires or threads poses particular challenges to the knitting process and, presumably due to the different material properties, can lead to warping of the knitted fabric and thus to instabilities in the production process. Such instabilities can manifest themselves in breaks in the wire during the knitting process and in irregularities in terms of structure and mechanical properties, both of which can result in a product of poor quality.
The problem addressed by the present invention was therefore to provide a method with high process stability for producing noble metal meshes on flat-bed knitting machines using noble-metal-containing wires and noble-metal-free threads.
The problem is solved by a method for producing a two-layer noble metal mesh on a flat-bed knitting machine, the flat-bed knitting machine comprising a first and a second needle bed, the method comprising the steps of
In the context of the invention, it was surprisingly identified that knitting a support mesh across both needle beds in the region in which it is connected to the layers of the noble metal mesh has a stabilizing effect on the knitting process. In other words, the at least partial embedding of the noble metal mesh in a single-layer support structure has the effect of reducing process disturbances in the form of breaks in the noble-metal-containing wire or irregularities in the noble metal knitted fabric.
The method according to the invention relates to knitting on a flat-bed knitting machine comprising a first and a second needle bed.
Knitting is characterized by the row-by-row production of the resulting knitted fabrics, in which process interlocking stitches are formed. During the knitting process on a flat-bed knitting machine comprising two needle beds, a knitting row is first formed on at least one of the needle beds. The next knitting row is then formed in the knitting direction, with the part of the knitted fabric that contains the first knitted row being referred to in the following as the “bottom”. The thread or wire is guided from one side of the needle bed or needle beds to the other side and back. If reference is made in the following to a “thread”, the relevant comment is also intended to apply to a corresponding “wire”. A knitting row therefore comprises a right side row and a wrong side row, which results from the thread guide. The thread can in this case be guided over just one or both needle beds in a knitting row. Typically, the thread for a complete knitting row can first be guided on the first needle bed (right side row), and then the thread is guided in the opposite direction on the same needle bed or the second needle bed (wrong side row). However, the thread can also be guided alternately on both needle beds in a right side and/or wrong side row, with connections being created between stitches on the two needle beds within one knitting row. The thread can be guided across the entire width of the needle bed or needle beds, but it is also possible to only knit across parts of the width of the needle beds. The width and also the shape of the knitted fabric can be determined depending on the width of the needle beds.
In the method according to the invention, all of the knitting processes take place simultaneously. This means that a plurality of sub-regions of the knitted fabric to be produced are knitted simultaneously on the two needle beds, i.e., the sub-regions are not produced one after the other in a plurality of knitting steps.
The method comprises providing at least one noble-metal-containing wire.
A noble-metal-containing wire is understood to mean a wire which consists of at least one noble metal or contains a significant proportion (>50 wt. %) of noble metal. In the context of the present invention, noble metals are understood to mean a metal selected from the group consisting of platinum metals, gold and silver. Platinum metals are understood to mean the metals of the so-called platinum group, i.e., platinum (Pt), palladium (Pd), iridium (Ir), rhodium (Rh), osmium (Os) and ruthenium (Ru).
The at least one noble-metal-containing wire preferably consists of platinum, a platinum alloy, palladium, or a palladium alloy. A platinum-based alloy contains more than 50 wt. % platinum, and other alloy components include in particular palladium, rhodium and ruthenium. A palladium-based alloy contains more than 50 wt. % palladium.
Preferably, the at least one noble-metal-containing wire consists of an alloy selected from the group consisting of platinum with 1-15 wt. % rhodium, platinum with 1-15 wt. % rhodium and 0.1-20 wt. % palladium, platinum with 1-15 wt. % rhodium, 0.1-20 wt. % palladium and 0.1-5 wt. % ruthenium, platinum with 1-15 wt. % rhodium, 0.1-40 wt. % palladium and 0.001-5 wt. % iridium, platinum with 1-15 wt. % rhodium, 0.1-20 wt.-% palladium and 0.001-5 wt. % tantalum, platinum with 1-15 wt. % rhodium, 0.001-5 wt. % iridium and 0.001-5 wt. % tantalum, palladium with 1-25 wt. % platinum, palladium with 1-20 wt. % platinum and 1-15 wt. % rhodium, palladium with 1-25 wt. % tungsten, palladium with 1-15 wt. % nickel, palladium with 0.001-5 wt. % rhodium, palladium with 1-15 wt. % copper, palladium with 1-15 wt. % copper and 1-15 wt. % nickel, and palladium with 1-30 wt. % cobalt.
Preferably, noble-metal-containing wires that have a diameter of 40-150 μm, preferably 50-130 μm, are used.
The at least one noble-metal-containing wire can be designed as a round wire, i.e., having a round cross section. In another embodiment, the wire can be designed as a flattened round wire or as a wire having a different cross section.
The at least one noble-metal-containing wire can comprise a plurality of wires, in this case also referred to as filaments, which can preferably be twisted together. The filaments can all consist of the same material, i.e., all containing noble metal, or consist of different materials, which in turn do not have to all contain noble metal.
In many cases, it can be advantageous to knit two or more noble-metal-containing wires together. In other words, when forming a stitch, a plurality of noble-metal-containing wires can be guided together. When knitting with a plurality of wires, in one embodiment the noble-metal-containing wires consist of the same material, and in further embodiments noble-metal-containing wires consisting of at least two different materials can be used. The plurality of wires can have the same or different diameters.
In the method according to the invention, the first layer of the two-layer noble metal mesh is knitted on the first needle bed and the second layer of the noble metal mesh is knitted on the second needle bed at the same time. In other words, during the knitting process, two parts of the noble metal mesh to be produced are knitted simultaneously on one needle bed each, so the two layers are not produced one after the other.
In the context of the present invention, “two-layer noble metal meshes” are understood to mean noble metal meshes which comprise two layers, wherein the layers can be interconnected via one or more of their respective abutting edges or can also be unconnected at their abutting edges. The two layers lie on top of each other, i.e., they overlap at least partially in the region of their surface extent. Noble metal meshes which, as in the case of the present invention, are interconnected on one side via the abutting edges of the two layers are also referred to as two-layer noble metal meshes. A single-layer noble metal mesh can be obtained by folding along the common abutting edge.
The first and the second layer of the two-layer noble metal mesh each comprise two abutting edges, i.e., each layer comprises an abutting edge on one side and another abutting edge on the other side. The first layer comprises the abutting edges S11 and S12 and the second layer comprises the abutting edges S21 and S22. The sides of the noble metal layers are to be understood in relation to the position of the abutting edges on the two needle beds perpendicular to the knitting direction. Depending on the shape of the relevant layer, the abutting edges of a layer may not intersect, as in the case of a rectangular layer, or they may intersect, as in the case of a semicircular layer, for example.
Abutting edges can be interconnected, preferably by at least one connecting knit stitch. However, abutting edges can also abut one another without being connected. The abutting edges are formed during the knitting process in the knitting direction from bottom to top. The two noble metal layers can also comprise an upper and/or lower edge or abutting edge; the presence of these edges depends on the shape of the relevant layer. A rectangular layer, for example, comprises a lower and an upper edge or abutting edge in addition to the two lateral abutting edges, whereas a semi-circular layer does not comprise any further edges or abutting edges.
The lower edges are understood to be the edges that are formed first in the knitting direction, i.e., at the bottom in the knitted fabric. Accordingly, the upper edges are understood to be the edges that are formed later in the knitting direction.
An abutting edge S11 of the first layer of the noble metal mesh at least partially abuts an abutting edge S21 of the second layer of the noble metal mesh. In addition, the respective other abutting edges of the first and the second layer of the noble metal mesh, i.e., the abutting edge S12 and the abutting edge S22, at least partially abut one another. In this context, “at least partially abutting one another” is understood to mean that the abutting edges abut one another over parts of their length in the knitting direction, i.e., over parts of the knitting rows that form them. In other words, the abutting edges can also be at least partially offset from one another.
The first and the second layer of the two-layer noble metal mesh can be at least partially connected at their abutting edges by connecting knit stitches. This means that the two layers are interconnected at their edge stitches via stitches formed from the at least one noble-metal-containing wire. This connection of the first and the second layer of the two-layer noble metal mesh can be made on only one side or on both sides. The connection or the connections can be made over the entire length or over parts of the length of the abutting edges. It can be advantageous for the connection to be made on one side over the entire length of the abutting edges.
In further embodiments, the connection can be made on both sides of the first and the second layer of the two-layer noble metal mesh at least over parts of their respective abutting edges, wherein these partial connections can be made at the same height, i.e., in the same knitting row or the same knitting rows, or at different heights. The partial joins can be made over the same length of the abutting edges on both sides, i.e., over the same number of knitting rows. However, the partial connections can also be made over different lengths of the abutting edges on both sides. In a preferred embodiment, the partial connections are made at least partially over the same knitting rows. In such an embodiment, knitting is therefore done at least partially in the round, i.e., circular-knitted; in other words, a ring-like structure is created via these knitting rows. It has been shown that knitting such an at least partially ring-like structure can have a further positive influence on the stability of the knitting process.
The reference for the height of the knitted fabric is the bottom knitting row of the knitted fabric. Even if the knitting of a layer is started in different knitting rows, the height of the whole knitted fabric remains the same; in other words. the layers of the knitted fabric can comprise a different number of knitting rows at different heights.
The first and the second layer of the two-layer noble metal mesh can preferably be knitted from a noble-metal-containing wire or noble-metal-containing wires of the same composition. However, the two layers can also be knitted from a noble-metal-containing wire or noble-metal-containing wires of different compositions.
Noble-metal-containing wire having the same or different diameters can be used to knit the first and second layers of the two-layer noble metal mesh. It has been proven favorable for the first and the second layer of the noble metal mesh to be knitted from a noble-metal-containing wire or noble-metal-containing wires of the same diameter.
The first and the second layer of the two-layer noble metal mesh can be knitted in the same or different knitting patterns. Different knitting patterns can result from different stitch lengths, floats or tucks, for example. In preferred embodiments, the first and the second layer of the noble metal mesh are knitted in the same knitting pattern.
The first and the second layer of the two-layer noble metal mesh can have the same or different lengths in the knitting direction and/or the same or different widths perpendicular to the knitting direction. The first and the second layer of the noble metal mesh preferably have the same length and the same width.
The first and the second layer of the two-layer noble metal mesh can have the same shape or different shapes. The first and the second layer of the two-layer noble metal mesh particularly preferably have the same shape. It may be advantageous for the first and the second layer of the two-layer noble metal mesh to have the shape of a semicircle. It can be particularly advantageous for these two semicircles to have the same width and the same length.
In preferred embodiments, the first and the second layer of the two-layer noble metal mesh are congruent; in other words, the two layers can have the same length, the same width and the same shape.
The method comprises providing at least one noble-metal-free support thread.
Suitable noble-metal-free support threads can be selected by routine tests, taking into account the final purpose of the two-layer noble metal mesh and any additional steps in the manufacturing process. Preferred noble-metal-free support threads can be removed after the production of the noble metal mesh, for example by dissolving in acidic or basic media, cutting, melting or flaming. Such support threads can be of a natural or synthetic organic nature or inorganic nature. Examples of suitable materials are polyamides, polyesters, cellulose fibers, cotton, acrylic-styrene polymers, nylon, PVA and other vinyl polymers, alginate, copper, silver, aluminum, or even metals having a low melting point such as tin alloys and lead alloys.
The at least one noble-metal-free support thread can consist of only one thread-like element; such individual thread-like elements are also referred to as filaments in the case of noble-metal-free threads. The noble-metal-free support thread can also consist of more than one filament, which can advantageously be twisted together. This plurality of filaments can be made of the same or different materials.
In the method according to the invention, a support mesh is knitted on the first and second needle bed simultaneously with the first and the second layer of the two-layer noble metal mesh using the at least one noble-metal-free support thread. In other words, the support mesh is knitted at the same time as the two layers of the noble metal mesh to be produced, so the two layers and the support mesh are not produced one after the other.
The term “support mesh” refers to the regions of the knitted fabric that are at least partially knitted using the noble-metal-free support thread. The support mesh can also comprise other threads or wires.
The knitted fabric comprises all knitting rows that are formed during the method. The knitted fabric comprises at least the first and the second layer of the two-layer noble metal mesh and the support mesh. However, the knitted fabric can also comprise other parts or regions.
Preferably, all knitting rows of the knitted fabric are knitted over the same width of the needle beds; in other words, the knitted fabric is preferably rectangular.
The support mesh comprises an abutting edge SH and an opposite edge KH. Depending on the shape of the support mesh, the abutting edge SH and the opposite edge KH may not intersect, as in the case of a rectangular support mesh, or they may intersect, as in the case of a semicircular support mesh, for example. The abutting edge SH and the edge KH are formed during the knitting process in the knitting direction from bottom to top.
The abutting edge SH of the support mesh abuts in each case an abutting edge S11 and S21 of the first and the second layer of the two-layer noble metal mesh. In other words, the edge of the support mesh that abuts the two layers of the two-layer noble metal mesh is referred to as the abutting edge SH. Accordingly, the abutting edge SH comprises the knitting rows in which both the layers of the two-layer noble metal mesh and the support mesh are knitted. The opposite edge KH is therefore the edge of the support mesh opposite the abutting edge SH in the same knitting rows, i.e., the abutting edge SH and the edge KH have the same length in the knitting direction. The edge KH does not abut either of the two layers of the two-layer noble metal mesh.
The shape of the edge and abutting edge of the support mesh is not further restricted. However, it has proven to be advantageous that the shape of the support mesh is designed in such a way that the overall shape of the knitted fabric is rectangular. In other words, the support mesh complements the layers of the noble metal mesh in such a way that the shape of the knitted fabric, comprising the noble metal layer or noble metal layers and support mesh, is rectangular overall. Accordingly, the shape of the support mesh preferably correlates with the shape of the first and second layers of the noble metal mesh. For example, the support mesh preferably has a concave shape if the first and second layers of the noble metal mesh have a convex shape.
In preferred embodiments, the abutting edge SH has the same length as the abutting edges S11 and S12. In other words, the abutting edge SH comprises the same knitting rows as the abutting edges S11 and S12, and the support mesh thus abuts the abutting edges of the layers of the two-layer noble metal mesh over the entire length of the layers of the noble metal mesh.
The abutting edge SH of the support mesh and the respective abutting edges S11 and S21 of the first and second layers of the two-layer noble metal mesh are interconnected via at least one knit stitch. In other words, the support mesh is at least partially connected to the two layers of the two-layer noble metal mesh during the knitting process. This stabilizes the knitting process. It may be preferable for the abutting edge SH of the support mesh to be connected over its entire length to the respective abutting edges S11 and S21 of the first and second layers of the two-layer noble metal mesh.
The connecting knit stitch or the connecting knit stitches can be formed from the at least one noble-metal-containing wire or the noble-metal-free support thread. Preferably, the connecting knit stitch or the connecting knit stitches are formed from the noble-metal-free support thread.
The support mesh is knitted with connecting stitches from both needle beds in the knitting row(s) in which the abutting edge SH of the support mesh is connected to the respective abutting edges S11 and S21 of the two layers of the noble metal mesh. The term “connecting stitches” is understood to mean the knit stitches that are formed between the first and the second needle bed. In other words, the support mesh is at least partially knitted in a single layer. It has been shown that the single-layer design of the support mesh in the region or regions that are connected to the layers of the noble metal mesh leads to an increase in process stability.
The noble-metal-free support thread can be knitted in parallel with the at least one noble-metal-containing wire, i.e., during knitting, stitches can be formed which comprise noble-metal-containing wire and support thread. In these cases, the relevant part of the resulting knitted fabric contains both noble metal and the material of the support thread. In other embodiments, the support thread can also be used for parts or regions of the knitted fabric that do not contain noble-metal-containing wire, i.e., in these cases, the resulting knitted fabric contains regions with and regions without noble-metal-containing wire.
The support mesh can comprise a plurality of regions. For example, the support mesh can also comprise knitting rows in which no noble-metal-containing wire is used, i.e., in which only the noble-metal-free support thread is used for knitting. In other words, the knitted fabric can comprise regions that do not contain noble-metal-containing wire. In this case, the support mesh can also comprise other edges in addition to the abutting edge SH and the edge KH. These edges can be formed in knitting rows in which no stitches of the layers of the noble metal mesh are knitted. In other words, the knitted fabric can also comprise knitting rows that are only formed by regions of the support mesh.
It may be preferable for the support mesh to be knitted in two layers in the regions comprising knitting rows that do not contain noble-metal-containing wire. In other words, the support mesh in these knitting rows cannot be knitted with connecting stitches between the first and second needle bed. These two layers can be connected at the edge stitches via connecting knit stitches; it can therefore be advantageous for the support mesh to have a tubular structure in these regions. It may also be preferable for the support mesh to be knitted in one layer in the regions that do not contain noble-metal-containing wire.
In preferred embodiments, the support mesh comprises single-layer knitted regions and two-layer knitted regions that do not comprise noble-metal-containing wire.
In preferred embodiments, the support mesh only abuts the two layers of the two-layer noble metal mesh at the abutting edges S11 and S21. It may also be preferable for the support mesh to also abut the two layers of the two-layer noble metal mesh at the respective other edges or abutting edges S12 and S22 of the two layers of the two-layer precious metal mesh. The abutting edge of the support mesh SH and the two abutting edges S12 and S22 of the two layers of the two-layer noble metal mesh can be interconnected via at least one knit stitch of the support thread. However, such a connection does not have to be made; in such embodiments, these abutting edges are not interconnected via knit stitches.
It may be preferable for the support mesh to also abut the respective lower and/or upper edges of the two layers of the two-layer noble metal mesh. The support mesh can thus only abut the lower or upper edges of the two layers of the precious metal mesh or the lower and upper edges. In such embodiments, the support mesh surrounds the two layers of the two-layer noble metal mesh on at least two sides.
It may be advantageous for the support mesh to surround the two layers of the two-layer noble metal mesh on more than two sides. In preferred embodiments, the support mesh surrounds at least 50% of the sides of the two layers of the two-layer noble metal mesh. This means that at least 50%, preferably at least 60%, even more preferably at least 80%, of the periphery of the two layers of the two-layer noble metal mesh is surrounded by the support mesh. It can be particularly preferable for the support mesh to completely surround the two layers of the two-layer noble metal mesh.
Preferably, all regions of the support mesh can be knitted from noble-metal-free support threads of the same composition. However, different regions can also be knitted from noble-metal-free support threads of different compositions. Different regions of the support mesh can be knitted in the same or different knitting patterns.
The method according to the invention can comprise further steps.
The method may comprise providing at least one further wire or thread. Suitable further wires or threads can be selected depending on the intended use and/or function in the manufacturing process or for the subsequent application of the noble metal mesh. For example, the further wire can be a wire made of a non-noble metal that is suitable for stabilizing the noble metal mesh when used in the reactor, for example a steel or stainless steel wire. In these cases, the method comprises simultaneously knitting regions of the knitted fabric using the at least one further wire or thread. In this case, the knitted fabric can comprise parts or regions that contain only the further wire or thread, or parts or regions that contain both the further wire or thread and the noble-metal-containing wire, or parts or regions that contain both the further wire or thread and the noble-metal-free support thread, or parts or regions that contain both the further wire or thread and the noble-metal-containing wire and the noble-metal-free support thread.
Preferably, the support mesh can be removed in a further step. Suitable processes are in principle known to a person skilled in the art and depend on the type of noble-metal-free support thread and noble-metal-containing wire used. The support mesh can, for example, be decomposed, dissolved, melted, flamed or cut off.
In a further step, a connecting stitch or a plurality of connecting stitches between the first and the second layer of the two-layer noble metal mesh can also be removed on at least one side; in other words, a connection between the two layers made via the edge stitches can be separated on at least one side. This makes it possible to produce a single-layer noble metal mesh that is at least partially connected on only one side, i.e., via only one abutting edge, of the two layers. In other words, a single-layer noble metal mesh can thus be obtained.
The invention is explained in more detail below with reference to drawings and an example. However, it is not limited to these embodiments.
Typically, the catalyst meshes 6 are knitted meshes that are produced, for example, from various platinum-rhodium alloys by knitting wire having a diameter of 76 μm. Catchment meshes 4 can also be provided.
In the example according to the invention and in the comparative example, on a flat-bed knitting machine comprising two needle beds, a rectangular layer (100 cm wide, 200 cm long) was knitted on each needle bed using a PtRh5 wire (76 μm diameter), the two layers being interconnected on one side. A cotton yarn was used as the support thread.
In the comparative example, a single-layer support mesh region was knitted using the cotton yarn on the unconnected side of both layers. A single-layer knitted fabric comprising two regions (noble metal layer and support mesh) was thus knitted on each of the two needle beds.
In the example according to the invention, a single-layer support mesh knitted across both needle beds was knitted on the unconnected side of the two layers. The two noble metal layers were therefore knitted only with stitches on one needle bed each, while the support mesh was knitted with stitches on both needle beds.
The knitted fabric of the example according to the invention had a more uniform structure than the knitted fabric of the comparative example. Such irregularities in the knitted fabric represent potential mechanical weak points that have a negative effect when the mesh is used in the reactor.
| Number | Date | Country | Kind |
|---|---|---|---|
| 22152845.8 | Jan 2022 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2022/080425 | 11/1/2022 | WO |
