EP4215661B1 - Procédé de fabrication de filets en métal précieux sur des tricoteuses rectilignes - Google Patents

Procédé de fabrication de filets en métal précieux sur des tricoteuses rectilignes Download PDF

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Publication number
EP4215661B1
EP4215661B1 EP22152845.8A EP22152845A EP4215661B1 EP 4215661 B1 EP4215661 B1 EP 4215661B1 EP 22152845 A EP22152845 A EP 22152845A EP 4215661 B1 EP4215661 B1 EP 4215661B1
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EP
European Patent Office
Prior art keywords
layer
precious metal
knitting
layers
abutting
Prior art date
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Application number
EP22152845.8A
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German (de)
English (en)
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EP4215661A1 (fr
Inventor
Pascal HIRSCHEL
Hendrik Dr. SPOD
Verena Wald
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Heraeus Deutschland GmbH and Co KG
Original Assignee
Heraeus Precious Metals GmbH and Co KG
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Application filed by Heraeus Precious Metals GmbH and Co KG filed Critical Heraeus Precious Metals GmbH and Co KG
Priority to EP22152845.8A priority Critical patent/EP4215661B1/fr
Priority to PCT/EP2022/080425 priority patent/WO2023138806A1/fr
Publication of EP4215661A1 publication Critical patent/EP4215661A1/fr
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Publication of EP4215661B1 publication Critical patent/EP4215661B1/fr
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    • D—TEXTILES; PAPER
    • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
    • D04B—KNITTING
    • D04B1/00—Weft knitting processes for the production of fabrics or articles not dependent on the use of particular machines; Fabrics or articles defined by such processes
    • D04B1/14—Other fabrics or articles characterised primarily by the use of particular thread materials
    • D—TEXTILES; PAPER
    • D02—YARNS; MECHANICAL FINISHING OF YARNS OR ROPES; WARPING OR BEAMING
    • D02G—CRIMPING OR CURLING FIBRES, FILAMENTS, THREADS, OR YARNS; YARNS OR THREADS
    • D02G3/00—Yarns or threads, e.g. fancy yarns; Processes or apparatus for the production thereof, not otherwise provided for
    • D02G3/02—Yarns or threads characterised by the material or by the materials from which they are made
    • D02G3/12—Threads containing metallic filaments or strips
    • D—TEXTILES; PAPER
    • D10—INDEXING SCHEME ASSOCIATED WITH SUBLASSES OF SECTION D, RELATING TO TEXTILES
    • D10B—INDEXING SCHEME ASSOCIATED WITH SUBLASSES OF SECTION D, RELATING TO TEXTILES
    • D10B2101/00—Inorganic fibres
    • D10B2101/20—Metallic fibres
    • D—TEXTILES; PAPER
    • D10—INDEXING SCHEME ASSOCIATED WITH SUBLASSES OF SECTION D, RELATING TO TEXTILES
    • D10B—INDEXING SCHEME ASSOCIATED WITH SUBLASSES OF SECTION D, RELATING TO TEXTILES
    • D10B2403/00—Details of fabric structure established in the fabric forming process
    • D10B2403/02—Cross-sectional features
    • D10B2403/024—Fabric incorporating additional compounds
    • D10B2403/0242—Fabric incorporating additional compounds enhancing chemical properties
    • D—TEXTILES; PAPER
    • D10—INDEXING SCHEME ASSOCIATED WITH SUBLASSES OF SECTION D, RELATING TO TEXTILES
    • D10B—INDEXING SCHEME ASSOCIATED WITH SUBLASSES OF SECTION D, RELATING TO TEXTILES
    • D10B2403/00—Details of fabric structure established in the fabric forming process
    • D10B2403/03—Shape features
    • D10B2403/032—Flat fabric of variable width, e.g. including one or more fashioned panels

Definitions

  • the present invention relates to a method for producing a two-layer precious metal net on a flat knitting machine that has a first and a second needle bed.
  • the method comprises providing at least one wire containing precious metal and knitting the precious metal net.
  • the first and second layers of the precious metal net are knitted simultaneously on the first and second needle beds and a supporting net is knitted using a supporting thread on the first and second needle beds.
  • An abutting edge of the supporting net is connected to the two layers of the precious metal net via connecting knitting stitches and in the knitting rows containing the connection, knitting takes place over both needle beds.
  • the heterogeneous noble metal-catalyzed oxidation of ammonia (NH 3 ) to nitric acid (HNO 3 , Ostwald process) or 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 are usually installed in the form of gas-permeable surface structures in the reaction zone of a flow reactor in a plane perpendicular to the flow direction of the fresh gas. Collection or catchment systems for the recovery of vaporized catalytically active components are also often based on such net-like structures. It is usually advisable to arrange several nets one behind the other and combine them to form a catalyst net stack.
  • the individual nets consist of fine precious metal wires that predominantly contain platinum (Pt), palladium (Pd), rhodium (Rh) or alloys of these metals.
  • Catchment nets in particular can also contain other components such as nickel.
  • a number of processes are known for producing such knitted fabrics, for example weaving, knitting and knitting. Weaving and knitting are particularly suitable for producing rectangular net webs with a homogeneous material distribution and structure. They offer little flexibility in terms of the shape design and material variability of the products to be manufactured. In an additional process step, the nets must be cut from the manufactured webs to a size and shape suitable for the reactors, which creates waste with precious metal components. In addition, the machines used require long set-up times and use a lot of material.
  • knitting offers greater flexibility: the weight per unit area as well as the structure, stretchability and strength of the available knitted fabrics can be varied by using the knitting patterns, wires (both in terms of thickness and material), needles and tension of the wire. Another advantage is the significantly shorter set-up times for the machines. It is also possible to use different materials in one knitted fabric; in so-called intarsia knitting, for example, different areas are made from different yarns or wires.
  • the length of a knitted fabric is not limited in principle, but in the case of flat knitting machines the maximum width is determined by the width of the needle beds.
  • Flat knitting machines or circular knitting machines can be used for knitting.
  • the needles are arranged in a circular needle bed and the thread or wire is fed in a circular motion.
  • Such machines allow tubular knitted goods to be produced in particular.
  • the shape and size of the knitted goods can be varied. The latter can also have more than one needle bed, between which the yarn or wire is guided back and forth during production using thread guides.
  • a single-layered knitted fabric can be produced in two ways: Firstly, when only one needle bed is used, i.e. only stitches are formed on one of the needle beds and knitted together. Secondly, stitches produced on the first needle bed can be knitted with stitches produced on the second needle bed, i.e. the thread is guided back and forth between the two needle beds within a forward and/or backward row. A two-layered knitted fabric is produced when both needle beds are knitted in parallel and the stitches produced on the first row of needles are not or only selectively knitted with the stitches produced on the second needle bed via the edge stitches. With this production method, two single-layered knitted fabrics or layers can also be produced in parallel on the first and second needle beds.
  • EP0364153A1 describes the use of an additional precious metal-free thread when knitting a precious metal net, which increases the process stability.
  • the additional thread is knitted parallel to the precious metal and can be removed from the homogeneous knitted fabric, consisting of precious metal material and thread material, after the knitting process if necessary.
  • This process was further developed so that the additional thread and the precious metal are not knitted in parallel, but simultaneously. In this way, precious metal-free areas can be obtained in the finished knitted fabric, which led to a reduction in the use of precious metals.
  • the object of the present invention was therefore to provide a method with high process stability for the production of precious metal nets on flat knitting machines using precious metal-containing wires and precious metal-free threads.
  • the method according to the invention relates to knitting on a flat knitting machine with a first and a second needle bed.
  • Knitting is characterized by the row-by-row production of the resulting knitted fabrics, in which interlocking stitches are formed.
  • 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, whereby the part of the knitted fabric that contains the first knitting row is referred to as "bottom” in the following.
  • the thread or wire is guided from one side of the needle bed or needle beds to the other side and back.
  • a knitting row therefore comprises a forward and a reverse row, which results from the thread guidance.
  • the thread guidance can take place in a knitting row over only one or both needle beds.
  • the thread can first be guided on the first needle bed for a complete knitting row (forward row), then the thread is guided in the opposite direction on the same needle bed or the second needle bed (reverse row).
  • the thread can also be guided alternately on both needle beds in a forward and/or backward row, whereby connections are created between stitches on the two needle beds within one knitting row.
  • the thread guide can be controlled via the The entire width of the needle bed or beds can be used, but it is also possible to knit over just parts of the width of the needle bed.
  • the width and shape of the knitted fabric can be determined depending on the width of the needle bed being knitted over.
  • the method comprises providing at least one wire containing precious metal.
  • a wire containing precious metals is understood to mean a wire that consists of at least one precious metal or contains a significant proportion (> 50% by weight) of precious metal.
  • precious 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 precious metal-containing wire consists of platinum, a platinum alloy, palladium or a palladium alloy.
  • a platinum-based alloy contains more than 50% by weight of platinum, and other alloy components include palladium, rhodium and ruthenium.
  • a palladium-based alloy contains more than 50% by weight of palladium.
  • 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.% tanta
  • precious metal-containing wires with a diameter of 40 - 150 ⁇ m, preferably 50 - 130 ⁇ m, are used.
  • the at least one wire containing precious metal can be designed as a round wire, i.e. with a round cross-section.
  • the wire can be designed as a flattened round wire or as a wire with a different cross-section.
  • the at least one wire containing precious metals can comprise several wires, in this case also referred to as filaments, which can preferably be twisted together.
  • the filaments can all be made of the same material, i.e. all contain precious metals, or they can be made of different materials, which in turn do not all have to contain precious metals.
  • the precious metal-containing wires can be guided together when forming a stitch.
  • the precious metal-containing wires consist of the same material; in other embodiments, precious metal-containing wires consisting of at least two different materials can be used.
  • the several wires can have the same or different diameters.
  • the first layer of the two-layer precious metal net is knitted simultaneously on the first needle bed and the second layer of the precious metal net is knitted on the second needle bed.
  • two parts of the precious metal net to be produced are knitted simultaneously on one needle bed each, so the two layers are not produced one after the other.
  • two-layer precious metal nets are understood to mean those precious metal nets that have two layers, whereby the layers can be connected to one another via one or more of their respective abutting edges or can also not be connected at their abutting edges.
  • the two layers lie on top of one another, i.e. they overlap at least partially in the area of their surface area.
  • Precious metal nets that, as in the case of the present invention, are connected to one another on one side via the abutting edges of the two layers are also referred to as two-layer precious metal nets.
  • the first and second layers of the two-layer precious metal mesh each have two butt edges, i.e. each layer has a butt edge on one side and another butt edge on the other side.
  • the first layer has the butt edges S11 and S12 and the second layer has the butt edges S21 and S22.
  • the sides of the precious metal layers are to be understood in relation to the position of the butt edges on the two needle beds perpendicular to the knitting direction.
  • the butt 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.
  • Butt edges can be connected to one another, preferably by at least one connecting knitting stitch. Butt edges can also abut one another without being connected. The butt edges are formed during the knitting process in the knitting direction from bottom to top.
  • the two precious metal layers can also have an upper and/or lower edge or butt edge; the presence of these edges depends on the shape of the respective layer.
  • a rectangular layer for example, has a lower and an upper edge or butt edge in addition to the two side butt edges, while a semicircular layer has no further edges or butt edges.
  • the lower edges are those edges that are formed first in the knitting direction, i.e. are located at the bottom of the fabric. Accordingly, the upper edges are those that are formed later in the knitting direction.
  • a butt edge of the first layer of the precious metal net S11 abuts at least partially against a butt edge of the second layer of the precious metal net S21.
  • the other butt edges of the first and second layers of the precious metal net i.e. the butt edge S12 and the butt edge S22, abut each other at least partially.
  • "At least partially abutting" is to be understood here as meaning that the butt edges abut each other over parts of their length in the knitting direction, i.e. over parts of the knitting rows that form them. In other words, the butt edges can also be at least partially offset from each other.
  • the first and second layers of the two-layer precious metal mesh can be connected at least partially at their abutting edges by connecting knitting stitches.
  • the two layers are connected to one another at their edge meshes via meshes that are formed from the at least one wire containing precious metal.
  • This connection of the first and second layers of the two-layer precious metal net can take place on just one side or on both sides.
  • the connection or connections can take place over the entire length or over parts of the length of the abutting edges. It can be advantageous for the connection to take place on one side over the entire length of the abutting edges.
  • connection on both sides of the first and second layers of the two-layer precious metal mesh can be made at least over parts of their respective abutting edges, whereby these partial connections can be made at the same height, i.e. in the same knitting row or rows, or at different heights.
  • the partial connections can be made over the same length of the abutting edges on both sides, i.e. over the same number of knitting rows.
  • the partial connections can also be made over a different length of the abutting edges on both sides.
  • the partial connections are made at least partially over the same knitting rows.
  • knitting is at least partially done in a circle or in a circular manner, in other words, a ring-like structure is created over these knitting rows. It has been shown that knitting such an at least partially ring-like structure can have a further positive effect 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 knitting of a layer begins in different knitting rows, the height of the entire knitted fabric remains the same, in other words, the layers of the knitted fabric at different heights can comprise a different number of knitting rows.
  • the first and second layers of the two-layer precious metal mesh can be knitted from a precious metal-containing wire or precious metal-containing wires of the same composition.
  • the two layers can also be knitted from precious metal-containing wire or precious metal-containing wires of different compositions.
  • Precious metal-containing wire with the same or different diameters can be used to knit the first and second layers of the two-layer precious metal net. It has proven advantageous for the first and second layers of the precious metal net to be knitted from precious metal-containing wire or precious metal-containing wires of the same diameter.
  • the first and second layers of the two-layer precious metal net can be knitted in the same or different knitting patterns. Different knitting patterns can be created, for example, by different stitch lengths, floats or catches. In preferred embodiments, the first and second layers of the precious metal net are knitted in the same knitting pattern.
  • the first and second layers of the two-layer precious metal net 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 second layers of the precious metal net have the same length and the same width.
  • the first and second layers of the two-layer precious metal net can have the same shape or different shapes.
  • the first and second layers of the two-layer precious metal net particularly preferably have the same shape. It can be advantageous for the first and second layers of the two-layer precious metal net 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.
  • the first and second layers of the two-layer precious 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 precious metal-free support thread.
  • Suitable non-precious metal support threads can be selected by routine testing and taking into account the final intended use of the two-layer precious metal mesh and any additional steps in the manufacturing process.
  • Preferred non-precious metal support threads can be removed after the precious metal mesh has been manufactured, for example by dissolving in acidic or basic media, cutting, melting or flaming.
  • Such support threads can be natural or synthetic, organic in nature or inorganic in 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 with a low melting point such as tin and lead alloys.
  • the at least one precious metal-free supporting thread can consist of only one thread-like element; such individual thread-like elements are also referred to as filaments in the case of precious metal-free threads.
  • the precious metal-free supporting thread can also consist of more than one filament, which can advantageously be twisted together. These multiple filaments can consist of the same or different materials.
  • a support net is knitted on the first and second needle bed simultaneously with the first and second layers of the two-layer precious metal net using the at least one precious metal-free support thread.
  • the support net is knitted simultaneously with the two layers of the precious metal net to be produced, so the two layers and the support net are not produced one after the other.
  • supporting net refers to the areas of the knitted fabric that are at least partially knitted using the precious metal-free supporting thread.
  • the supporting net can also include other threads or wires.
  • the knitted fabric comprises all the rows of knitting that are formed during the process.
  • the knitted fabric comprises at least the first and second layers of the two-layer precious metal mesh and the support mesh.
  • the knitted fabric can also comprise other parts or areas.
  • all rows of knitting 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 net has a butt edge SH and an opposite edge KH.
  • the butt edge SH and the opposite edge KH may not intersect, as in the case of a rectangular support net, or may intersect, as in the case of a semicircular support net.
  • the butt edge SH and the edge KH are formed during the knitting process in the knitting direction from bottom to top.
  • the butt edge SH of the support net abuts against a butt edge S11 and S21 of the first and second layers of the two-layer precious metal net.
  • the edge of the support net that abuts against the two layers of the two-layer precious metal net is referred to as the butt edge SH.
  • the butt edge SH accordingly includes the knitting rows in which both the layers of the two-layer precious metal net and the support net are knitted.
  • the opposite edge KH accordingly connects the butt edge SH opposite edge of the support net in the same knitting rows, ie the butt edge SH and the edge KH have the same length in the knitting direction.
  • the edge KH does not abut one of the two layers of the two-layer precious metal net.
  • the shape of the edge and abutting edge of the support net is not further restricted.
  • the shape of the support net is designed such that the shape of the knitted fabric is rectangular overall.
  • the support net complements the layers of the precious metal net such that the shape of the knitted fabric, comprising the precious metal layer or layers and the support net, is rectangular overall.
  • the shape of the support net preferably correlates with the shape of the first and second layers of the precious metal net.
  • the support net preferably has a concave shape if the first and second layers of the precious metal net have a convex shape.
  • the abutting edge SH has the same length as the abutting edges S11 and S12.
  • the abutting edge SH comprises the same knitting rows as the abutting edges S11 and S12, so the support net abuts the abutting edges of the layers of the two-layer precious metal net over the entire length of the layers of the precious metal net.
  • the abutting edge SH of the support net and the respective abutting edges S11 and S21 of the first and second layers of the two-layer precious metal net are connected to one another via at least one knitting stitch.
  • the support net is at least partially connected to the two layers of the two-layer precious metal net during the knitting process. This stabilizes the knitting process.
  • the abutting edge SH of the support net is connected over its entire length to the respective abutting edges S11 and S21 of the first and second layers of the two-layer precious metal net.
  • the connecting knitting stitch or the connecting knitting stitches can be formed from the at least one precious metal-containing wire or the precious metal-free supporting thread.
  • the connecting knitting stitch or the connecting knitting stitches are formed from the precious metal-free supporting thread.
  • the support net is knitted in the knitting row(s) in which the butt edge SH of the support net is connected to the respective butt edges of the two layers of the precious metal net S11 and S21, with connecting stitches from both needle beds.
  • Connecting stitches are understood to mean those knitting stitches that are between the first and the second needle bed.
  • the support net is at least partially knitted in one layer. It has been shown that the single-layer design of the support net in the area or areas that are connected to the layers of the precious metal net leads to an increase in process stability.
  • the precious metal-free support thread can be knitted in parallel with the at least one precious metal-containing wire, i.e., during knitting, stitches can be formed that comprise precious metal-containing wire and support thread.
  • the relevant part of the resulting knitted fabric contains both precious metal and the material of the support thread.
  • the support thread can also be used for parts or areas of the knitted fabric that do not contain precious metal-containing wire, i.e., in these cases, the resulting knitted fabric contains areas with and areas without precious metal-containing wire.
  • the support net can comprise several areas.
  • the support net can also comprise knitting rows in which no wire containing precious metals is used, i.e. in which only the precious metal-free support thread is used for knitting.
  • the knitted fabric can comprise areas that do not contain any wire containing precious metals.
  • the support net can comprise other edges in addition to the butt edge SH and the edge KH. Such edges can be formed in knitting rows in which no stitches of the layers of the precious metal net are knitted.
  • the knitted fabric can also have knitting rows that are only formed by areas of the support net.
  • the support net is knitted in two layers in the areas with knitting rows that do not contain a wire containing precious metals. In other words, the support net cannot be knitted in these knitting rows with connecting stitches between the first and second needle beds. These two layers can be connected at the edge stitches via connecting knitting stitches, so it may be advantageous for the support net to have a tubular structure in these areas. It may also be preferred that the support net is knitted in one layer in the areas that do not contain a wire containing precious metals.
  • the support mesh comprises single-layer knitted regions and double-layer knitted regions that do not comprise any noble metal-containing wire.
  • the support net only abuts the two layers of the two-layer precious metal net at the abutting edges S11 and S21. It may also be preferred that the support net also abuts the two layers of the two-layer precious metal net at the other edges or abutting edges of the two layers of the two-layer precious metal net S12 and S22.
  • the abutting edge of the support net SH and the two abutting edges of the two layers of the two-layer precious metal net S12 and S22 can be connected to one another via at least one knitting stitch of the support thread. However, such a connection does not have to be made; in such embodiments, these abutting edges are not connected to one another via knitting stitches.
  • the support net also abuts the respective lower and/or upper edges of the two layers of the two-layer precious metal net.
  • the support net can only abut the lower or upper edges of the two layers of the precious metal net or the lower and upper edges.
  • the support net surrounds the two layers of the two-layer precious metal net on at least two sides.
  • the support net can surround the two layers of the two-layer precious metal net on more than two sides.
  • the support net surrounds the sides of the two layers of the two-layer precious metal net by at least 50%. This means that at least 50% of the circumference of the two layers of the two-layer precious metal net is surrounded by the support net, more preferably at least 60%, even more preferably at least 80%. It can be particularly preferred for the support net to completely surround the two layers of the two-layer precious metal net.
  • all areas of the support net can be knitted from precious metal-free support threads of the same composition.
  • different areas can also be knitted from precious metal-free support threads of different compositions.
  • Different areas of the support net can be knitted in the same or different knitting patterns.
  • the method according to the invention may comprise further steps.
  • the method may comprise providing at least one additional wire or thread.
  • Suitable additional wires or threads may be used depending on the intended use and/or function in the manufacturing process or for the subsequent application of the precious metal mesh.
  • the additional wire can be a wire made of a non-noble metal that is suitable for stabilizing the precious metal mesh when used in the reactor, for example it can be a steel or stainless steel wire.
  • the method comprises the simultaneous knitting of regions of the knitted fabric using the at least one additional wire or thread.
  • the knitted fabric can comprise parts or regions that contain only the additional wire or thread, or parts or regions that contain both the additional wire or thread and the precious metal-containing wire, or parts or regions that contain both the additional wire or thread and the precious metal-free support thread, or parts or regions that contain both the additional wire or thread and the precious metal-containing wire and the precious metal-free support thread.
  • the support net can be removed in a further step. Suitable methods are known in principle to the person skilled in the art and depend on the type of precious metal-free support thread used and the precious metal-containing wire.
  • the support net can, for example, be decomposed, dissolved, melted, flamed or cut off.
  • a connecting mesh or several connecting meshes between the first and second layers of the two-layer precious metal net can be removed on at least one side, in other words, a connection between the two layers via the edge meshes can be separated on at least one side.
  • illustration 1 shows a schematic of a vertically positioned flow reactor 1 for the heterogeneous catalytic combustion of ammonia.
  • the catalyst system 2 forms the actual reaction zone of the flow reactor 1. It comprises a catalyst packing 3 and downstream catchment nets 4.
  • the catalyst packing 3 comprises several catalyst nets 6 arranged one behind the other in the flow direction 5 of the fresh gas.
  • the catalyst nets 6 are knitted nets, which are produced, for example, by knitting wire with a diameter of 76 ⁇ m from various platinum-rhodium alloys.
  • Catchment nets 4 can also be provided.
  • Figure 2 shows schematically the thread guide in an exemplary forward row of a knitting row between two needle beds 10 and 11 of a flat knitting machine. Needles that are used during the knitting process are highlighted, the direction of the thread guide is indicated by arrows. Each circle symbolizes a needle.
  • Figure 2 A the thread guide for a thread or wire 12 is illustrated for a forward row in which only stitches are knitted on the first needle bed. If in the back row and all further complete knitting rows only stitches are knitted on the first needle bed 10, a single-layered knitted fabric is obtained. If in the back rows only stitches are knitted on the second needle bed 11, a two-layered knitted fabric is obtained.
  • the knitting pattern used also contains a float: stitches are only formed on every second needle of the needle bed.
  • Figure 2 B shows the forward row for a single-layered knit, where 12 stitches are knitted with the thread or wire on the first and second needle beds 10 and 11.
  • Figure 3 shows embodiments of two-layer precious metal nets that can be produced using the method according to the invention on flatbed knitting machines with two needle beds.
  • Figure 3 A and B show a two-layer precious metal net 100 consisting of two rectangular layers 101 and 102, with the frontal view in Figure 3 A only the first layer 101 is visible.
  • Figure 3B shows a view of the precious metal net 100 opened along the abutting edges 111 of the first layer 101 or the abutting edge 112 of the second layer 102 that abuts against it.
  • the abutting edge 112 of the first layer is congruent with the abutting edge 113 of the second layer 102.
  • the "opening" is to be understood virtually at this point and serves to better understand the Invention.
  • the two layers 101 and 102 are connected along their abutting edges 112 and 113 to the abutting edge 120 of a support net 130 (in the illustration in Figure 3B the connection to the abutting edge 113 is no longer shown for better illustration).
  • the support net 130 is knitted in a single layer from a support thread, preferably a cotton thread, from connecting stitches from both needle beds.
  • the edge 121 of the support net 130 opposite the abutting edge 120 does not abut any other sides or edges of the precious metal net 20'.
  • Figure 3C shows a two-layer precious metal net 200 that is surrounded on two sides by a support net. Only the frontal view of a first rectangular layer 201 is shown, which lies congruently over another layer. Both layers are connected to two support net areas 230 and 231 via their respective two abutting edges (only the abutting edges of the first layer 201 (210 and 211) are visible in the illustration). The first area of the support net 230 is made in one layer. The second area 231 can be made in one or two layers.
  • Figure 3D shows a Fig. 3 C analogous view of a two-layer precious metal net 300, which is surrounded by a support net on two adjacent sides.
  • a precious metal net of this embodiment for example, knitting of the lower region 331 of the support net can be started, after which the two layers of the precious metal net 300 and a further region 330 of the support net are manufactured simultaneously. In the corresponding knitting rows, stitches are thus formed from the support material and the wire containing precious metal.
  • the two regions of the support net 330 and 331 can expediently be connected to one another.
  • Figure 3 E shows a Fig. 3 C analogous view of a two-layer precious metal net 400, which is surrounded on all four sides by a support net.
  • the support net is expediently divided into the areas 430, 431, 432 and 433, these areas are preferably connected to one another.
  • a two-layer precious metal net 500 is also surrounded on four sides by support net areas (530, 531, 532, 533).
  • One of the support net areas 532 does not abut the precious metal net 500, but is spaced from the precious metal net by a gap 534.
  • all areas are manufactured simultaneously, i.e. during a single knitting process, in the knitting direction from bottom to top.
  • Figure 3 G shows a Fig. 3 C analogous view of a two-layer precious metal net 600 made of two semicircular layers (only the first layer 601 is visible). The two layers are on one side along the respective abutting edge (610 in the case of the first layer 601) with the support net 630 via its abutting edge 620.
  • Figure 3 H also shows a two-layer precious metal net 700 formed from two semicircular layers, in which the layers are surrounded at both abutting edges by two support net regions 730 and 731.
  • a rectangular layer (100 cm wide, 200 cm long) was knitted on each needle bed on a flat knitting machine with two needle beds using a PtRh5 wire (76 ⁇ m diameter), with the two layers being connected to one another on one side.
  • a cotton yarn was used as the support thread.
  • a single-layer support net area was knitted with the cotton yarn on the unconnected side of both layers.
  • a single-layer knitted fabric with two areas (precious metal layer and support net) was therefore knitted on each of the two needle beds.
  • a single-layer support net knitted over both needle beds was knitted on the unconnected side of the two layers. The two precious metal layers were therefore only knitted with stitches on one needle bed each, while the support net 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 on the use of the mesh in the reactor.

Landscapes

  • Engineering & Computer Science (AREA)
  • Textile Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Knitting Of Fabric (AREA)

Claims (14)

  1. Procédé pour la fabrication d'un filet en métal précieux à deux couches sur une tricoteuse rectiligne, dans lequel la tricoteuse rectiligne présente une première et une seconde fonture (10, 11), comprenant les étapes consistant à
    - fournir au moins un fil contenant un métal précieux (12),
    - fournir au moins un fil de support exempt de métal précieux,
    - tricoter une première couche (101, 201, 301, 401, 501, 601, 701) du filet en métal précieux sur la première fonture (10) et une seconde couche (102) du filet en métal précieux sur la seconde fonture (11),
    dans lequel la première couche (101, 201, 301, 401, 501, 601, 701) dispose des lisières S11 et S12 (110, 210, 310, 410, 510, 610, 710) et la seconde couche (102) dispose des lisières S21 et S22 (111, 211, 311, 411, 511, 611, 711 112, 113), dans lequel la lisière S11 est au moins partiellement en butée contre la lisière S21 et la lisière S12 est au moins partiellement en butée contre la lisière S22,
    - tricoter un filet de support (130, 230, 330, 430, 530, 630, 730) sur la première et la seconde fonture (10, 11) à l'aide de l'au moins un fil de support exempt de métal précieux, dans lequel le filet de support (130, 230, 330, 430, 530, 630, 730) dispose d'une lisière SH (120, 220, 320, 420, 520, 620, 720) et d'un bord KH (121, 221, 321, 421, 521, 621, 721) opposé à la lisière, dans lequel la lisière SH (120, 220, 320, 420, 520, 620, 720) est en butée contre respectivement une lisière S11 et S21 des deux couches du filet en métal précieux,
    dans lequel tous les processus de tricotage sont effectués simultanément,
    caractérisé en ce que
    la lisière SH (120, 220, 320, 420, 520, 620, 720) du filet de support est reliée aux lisières S11 et S21 respectives des deux couches du filet en métal précieux par l'intermédiaire d'au moins une maille de tricot et en ce que le filet de support est tricoté dans les rangs de tricot, sur lesquels la lisière SH (120, 220, 320, 420, 520, 620, 720) du filet de support est reliée aux lisières respectives des deux couches du filet en métal précieux S11 et S21, avec des mailles de liaison des deux fontures (10, 11).
  2. Procédé selon la revendication 1, dans lequel l'au moins un fil contenant un métal précieux est constitué de platine, d'un alliage de platine, de palladium ou d'un alliage de palladium.
  3. Procédé selon l'une des revendications précédentes, dans lequel la première et la seconde couche du filet en métal précieux à deux couches sont tricotées à partir d'un fil contenant un métal précieux ou de fils contenant un métal précieux de même composition.
  4. Procédé selon l'une des revendications précédentes, dans lequel la première et la seconde couche du filet en métal précieux sont tricotées à partir d'un fil contenant un métal précieux ou de fils contenant un métal précieux de même diamètre.
  5. Procédé selon l'une des revendications précédentes, dans lequel la première et la seconde couche du filet en métal précieux sont tricotées selon le même dessin de tricotage.
  6. Procédé selon l'une des revendications précédentes, dans lequel la première (101, 201, 301, 401, 501, 601, 701) et la seconde couche (102) du filet en métal précieux coïncident.
  7. Procédé selon l'une des revendications précédentes, dans lequel la première (101, 201, 301, 401, 501, 601, 701) et la seconde couche (102) du filet en métal précieux à deux couches sont reliées au moins partiellement par au moins une maille de tricot de liaison au niveau de leurs lisières.
  8. Procédé selon l'une des revendications précédentes, dans lequel la lisière SH du filet de support (120, 220, 320, 420, 520, 620, 720) a la même longueur que les lisières S11 etS12 (110, 210, 310, 410, 510, 610, 710, 111, 211, 311, 411, 511,611, 711, 112, 113) de la première et de la seconde couche (101, 201, 301, 401, 501, 601, 701, 102) du filet en métal précieux à deux couches.
  9. Procédé selon l'une des revendications précédentes, dans lequel la forme du filet de support est corrélée avec la forme de la première et de la seconde couche du filet en métal précieux à deux couches.
  10. Procédé selon l'une des revendications précédentes, dans lequel la lisière SH du filet de support (120, 220, 320, 420, 520, 620, 720) est reliée sur l'intégralité de sa longueur aux lisières S11 et S21 (110, 210, 310, 410, 510, 610, 710, 111, 211, 311, 411, 511, 611, 711 112, 113) respectives de la première et de la seconde couche (101, 201, 301, 401, 501, 601, 701, 102) du filet en métal précieux à deux couches.
  11. Procédé selon l'une des revendications précédentes, dans lequel le filet de support entoure au moins à 50 % les côtés de la première et de la seconde couche (101, 201, 301, 401, 501, 601, 701, 102) du filet en métal précieux à deux couches.
  12. Procédé selon la revendication précédente, dans lequel le filet de support comprend plusieurs zones.
  13. Procédé selon la revendication précédente, dans lequel le procédé comprend une étape supplémentaire pendant laquelle le filet de support est retiré.
  14. Procédé selon l'une des revendications précédentes, dans lequel le procédé comprend une étape supplémentaire pendant laquelle une maille de liaison ou des mailles de liaison entre la première et la seconde couche du filet en métal précieux sont retirées sur un côté.
EP22152845.8A 2022-01-24 2022-01-24 Procédé de fabrication de filets en métal précieux sur des tricoteuses rectilignes Active EP4215661B1 (fr)

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EP22152845.8A EP4215661B1 (fr) 2022-01-24 2022-01-24 Procédé de fabrication de filets en métal précieux sur des tricoteuses rectilignes
PCT/EP2022/080425 WO2023138806A1 (fr) 2022-01-24 2022-11-01 Procédé de fabrication de maillage de métal noble sur des machines à tricoter à plat

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EP22152845.8A EP4215661B1 (fr) 2022-01-24 2022-01-24 Procédé de fabrication de filets en métal précieux sur des tricoteuses rectilignes

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Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
ES2037959T3 (es) 1988-10-12 1993-07-01 Johnson Matthey Public Limited Company Telas metalicas.
GB9016787D0 (en) 1990-07-31 1990-09-12 Heywood Alan E Improvements in or relating to catalysts and getter systems
ATE278468T1 (de) * 2001-02-08 2004-10-15 Umicore Ag & Co Kg Dreidimensionale, in zwei oder mehreren schichten gestrickte katalysatornetze
EP3779005A1 (fr) 2019-08-16 2021-02-17 Umicore Ag & Co. Kg Tricotage de filets en métal précieux à l'aide du matériau non précieux sur le bord, filet en métal précieux obtenu et un procédé utilisant le filet en métal précieux
EP3795728A1 (fr) 2019-09-17 2021-03-24 Umicore Ag & Co. Kg Tricotage de filets en métal précieux et procédé utilisant ces filets

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