EP0170051A2 - Diaphragm for alkaline electrolysis, and its manufacturing process - Google Patents
Diaphragm for alkaline electrolysis, and its manufacturing process Download PDFInfo
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- EP0170051A2 EP0170051A2 EP85107908A EP85107908A EP0170051A2 EP 0170051 A2 EP0170051 A2 EP 0170051A2 EP 85107908 A EP85107908 A EP 85107908A EP 85107908 A EP85107908 A EP 85107908A EP 0170051 A2 EP0170051 A2 EP 0170051A2
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- diaphragm
- layer
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- grains
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- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
- C25B13/00—Diaphragms; Spacing elements
- C25B13/02—Diaphragms; Spacing elements characterised by shape or form
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- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
- C25B13/00—Diaphragms; Spacing elements
- C25B13/04—Diaphragms; Spacing elements characterised by the material
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/24—Structurally defined web or sheet [e.g., overall dimension, etc.]
- Y10T428/24355—Continuous and nonuniform or irregular surface on layer or component [e.g., roofing, etc.]
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/249921—Web or sheet containing structurally defined element or component
- Y10T428/249953—Composite having voids in a component [e.g., porous, cellular, etc.]
- Y10T428/249967—Inorganic matrix in void-containing component
- Y10T428/249969—Of silicon-containing material [e.g., glass, etc.]
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/249921—Web or sheet containing structurally defined element or component
- Y10T428/249953—Composite having voids in a component [e.g., porous, cellular, etc.]
- Y10T428/249967—Inorganic matrix in void-containing component
- Y10T428/24997—Of metal-containing material
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T442/00—Fabric [woven, knitted, or nonwoven textile or cloth, etc.]
- Y10T442/10—Scrim [e.g., open net or mesh, gauze, loose or open weave or knit, etc.]
- Y10T442/102—Woven scrim
- Y10T442/109—Metal or metal-coated fiber-containing scrim
- Y10T442/11—Including an additional free metal or alloy constituent
- Y10T442/112—Particulate free metal or alloy constituent
Definitions
- the invention relates to a diaphragm for alkaline electrolysis, in particular for alkaline water electrolysis, with a fine-pored, in particular ceramic layer, and to a method for producing the same.
- the following description therefore largely refers to these special diaphragms.
- Alkaline water electrolysis is generally carried out at temperatures below 90 ° C. These relatively low temperatures are necessary because of the low chemical resistance of the commercially used asbestos diaphragms in hot KOH. For reasons of stability, the diaphragms must also be chosen much thicker than would be required for the actual electrolysis. This in turn causes an undesirable high electrolysis voltage and makes the entire process, from an energy perspective, appear uneconomical.
- the "sandwich construction" also has a disadvantage that does not occur with the usual energetically disadvantageous constructions: the diaphragm only remains functional if no deposits form on the electrodes, which can then propagate further into the diaphragm located in the immediate vicinity (zero distance). Of course, this presupposes that the entire cell system including its periphery must be so corrosion-resistant that practically no corrosion takes place. Corrosion products would, as a result of the electrode reactions, either deposit or deposit cathodically as metals or anodically as hydrated oxides and pass from the electrodes into the diaphragm and clog it or even lead to short circuits. In practice, however, it is very difficult or at least very expensive to maintain a corrosion-free state.
- the energy-saving and thus economical reduction of the electrode spacing on the one hand is associated with the need for expensive systems, while the structurally cheaper solution working with a noticeable distance between the diaphragm electrodes is energetically disadvantageous.
- a diaphragm of the type mentioned at the outset which is characterized by coarser grains which protrude from the surface and are distributed over the surface and which protrude from the surface on one or both sides of the diaphragm.
- the diaphragm preferably comprises a framework for the fine-porous layer, which is formed in particular by an oxidized metal net, which also allows the handling of large, thin diaphragms.
- the diaphragm according to the invention specifically comprises a fine-porous layer which is formed by oxidation of sintered metal or pressed metal powder based on nickel until a sufficiently electrically insulating layer is obtained, in particular on or on an oxidized metal mesh support, the coarser grains of oxidized metal protruding from the layer. or metal oxide.
- the coarser grains protruding from the surface make it somewhat minimal Distance between the actual fine-pored diaphragm and an immediately applied electrolyte- and gas-permeable electrode made of perforated plate or the like. maintained so that the function of the diaphragm is maintained even over longer times even under conditions of the electrolysis cell that are not absolutely corrosion-free, although the distance between the electrode (adjustable via the grain size and the protruding part of the grains) from the fine-pored diaphragm layer is so small, that there are no significant energy losses.
- the coarser grains preferably have a diameter of about 10 to 250 ⁇ m, in particular one of 50 to 150 ⁇ m, and they preferably protrude from the surface by about 50 to 70%. They are relatively thin (and usually indiscriminately) distributed over the surface, since the stability and thickness of the electrode generally prevent "sagging" between the contact points, which can therefore be relatively far apart.
- the average distance between the coarser grains is expediently chosen to be up to 100 times the grain diameter, grain spacings in the range from 10 to 50 times the grain diameter being preferred.
- the coarser grains integrated in the fine-porous diaphragm layer consist made of oxidized metal and are "baked" into the layer during the manufacture of the diaphragm. It is therefore expedient to use coarse-grained powders made of iron, cobalt, nickel or mixtures thereof for the production.
- the diaphragm is expediently produced by oxidatively sintering a further metal or oxide powder with a coarser grain along the surface onto the fine-pore layer of the actually writable diaphragm.
- a fine-grained metal powder (grain size approx. 1 to 5 ⁇ m) is compacted on a mesh as a carrier, in particular on a nickel mesh carrier, by means of a pressing or rolling process, and a metal powder with a coarser grain size is again applied to this fine-pored metal powder layer 10 to 250 ⁇ m) thinly distributed and then. (with little pressure application) pressed or rolled.
- the coarser metal powder is temporarily embedded and fixed in the fine-pored layer. In this way, small "knobs" protrude beyond the surface of the fine-pored layer.
- This arrangement is fired oxidatively in a further step, so that the metal structure is largely converted into an oxidic diaphragm.
- FIG. 1 schematically shows the structure of the diaphragm 1 with a fine-porous layer 2 on a mesh-like carrier 3.
- Coarser grains 4 which have been oxidized on are coagulated into the fine-porous layer 2 with a space 5 between them.
- Gas and electrolyte-permeable electrodes 6 for example perforated sheet metal or porous, galvanically produced thin electrodes
- nickel powder and a nickel carrier are used for the manufacture of the diaphragm and coarse-grain powder of metals for the "knobs", which is produced on the basis of comparable heat development should be oxidizable during the oxidation process together with the press and sintered layer and should be able to be integrated into the fine-porous layer.
- the pressure for the manufacture of the diaphragm depends on the desired porosity and the embedding depth of the coarser grains, whereby an unburnt layer should be created in all cases.
- Preferred dimensions are given on the left-hand edge of FIG. 1 and it can be seen that the distance of the electrode from the actual diaphragm can be kept variable up to in particular 200 ⁇ m, depending on the grain size and injection pressure when the coarser grains are applied.
- the fine-porous diaphragm structure is removed from the direct range of the electrode only as far as is necessary to avoid the harmful side effects of the electrodes on the diaphragm during electrolysis operation, the advantageous small electrode spacing being retained.
- microspacers or "knobs” formed in the manner described have no hydrophobic properties and are therefore particularly advantageous for gas-developing electrochemical processes since there are no harmful side effects due to the so-called bubble curtain effect on the cell voltage may occur.
- the layer thickness was 40 mg / cm 2 .
- a nickel mesh with a mesh size of 0.20 mm and a wire thickness of 0.125 mm was placed over it and the whole was cold-compressed with a pressure of approx. 200 N / cm 2 . That way
- a (unfired) preform in the form of a nickel mesh support with a powder layer on one side.
- Iron powder with a grain size of 10D to 150 ⁇ m was then uniformly distributed over a metal plate in a surface density of 10 mg / cm 2 .
- the diaphragm preform was placed on this layer and pressed in under slight pressure (approx. 10 N / cm 2 ).
- the second page was treated analogously.
- This preform was then oxidatively sintered in air in a furnace at 1000 ° C. for 15 minutes, whereby a diaphragm with “microspacers” suitable for installation in an electrolysis cell with adjacent electrodes was obtained.
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- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Electrodes For Compound Or Non-Metal Manufacture (AREA)
- Electrolytic Production Of Non-Metals, Compounds, Apparatuses Therefor (AREA)
- Manufacture Of Macromolecular Shaped Articles (AREA)
Abstract
Ein Diaphragma für alkalische Elektrolysen, insbesondre für die alkalische Wasserelektrolyse, mit einer feinporösen, insbesondere keramischen Schicht, die vorzugsweise von einem gerüstgehenden Träger oder Netz gestützt wird und an der die Elektroden sandwichartig anliegen, wird mit über die Fläche verteilten, in die feinporöse Schicht integrierten gröberen Körnern ein- oder beidseitig versehen, die aus der Oberfläche vorragen und trotz anliegender Elektrode für einen gewissen Minimalabstand zwischen Diaphragma und Elektrode sorgen, so daß durch unvermeidbare Korrosionsphänomene innerhalb der Apparatur bedingte Abscheidungen auf den Elektroden nicht in das Diaphragma hineinwachsen können. Diese gröberen Körner von etwa 10 - 250µm werden bei der Herstellung des Diaphragmas vor dem Sintern in dünner verteilung auf die Oberfläche gebracht und unter geringer Druckanwendung in die Oberfläche soweit hineingetrieben, daß sie noppenartig daraus vorstehen.A diaphragm for alkaline electrolysis, in particular for alkaline water electrolysis, with a fine-porous, in particular ceramic layer, which is preferably supported by a framework or mesh and on which the electrodes are sandwiched, is integrated into the fine-porous layer with the surface being distributed coarser grains on one or both sides, which protrude from the surface and provide a certain minimum distance between the diaphragm and the electrode despite the electrode being attached, so that deposits on the electrodes caused by unavoidable corrosion phenomena within the apparatus cannot grow into the diaphragm. These coarser grains of approx. 10 - 250µm are brought to the surface in a thin distribution during the manufacture of the diaphragm before sintering and are driven into the surface with little pressure so that they protrude from it like a nub.
Description
Die Erfindung bezieht sich auf ein Diaphragma für alkalische Elektrolysen, insbesondere für die alkalische Wasserelektrolyse, mit einer feinporösen, insbesonderen keramischen Schicht sowie auf ein Verfahren zur Herstellung desselben.The invention relates to a diaphragm for alkaline electrolysis, in particular for alkaline water electrolysis, with a fine-pored, in particular ceramic layer, and to a method for producing the same.
Ein besonderes Interesse gilt dabei Diaphragmen mit einer durch Oxidation von Sintermetall oder gepreßtem Metallpulver gebildeten feinporösen isolierenden Schicht auf Nickeloxidbasis an bzw. auf einem gerüstgebenden aufoxidierten Metallträger, wie sie von der Anmelderin für die alkalische Wasserelektrolyse entwickelt worden sind. Die nachfolgende Beschreibung bezieht sich daher weitgehend auf diese speziellen Diaphragmen.Of particular interest here is diaphragms with a fine-porous insulating layer based on nickel oxide formed by oxidation of sintered metal or pressed metal powder on or on a framework-providing, oxidized metal support, as developed by the applicant for alkaline water electrolysis. The following description therefore largely refers to these special diaphragms.
Die alkalische Wasserelektrolyse wird im allgemeinen bei Temperaturen unterhalb von 90 °C durchgeführt. Diese relativ niedrigen Temperaturen sind wegen der geringen chemischen Beständigkeit der kommerziell angewandten Asbestdiaphragmen in heißer KOH notwendig. Die Diaphragmen müssen ferner aus Stabilitätsgründen weit dicker gewählt werden,als für die eigentliche Elektrolyse erforderlich wäre. Das bedingt wiederum eine unerwünscht hohe Elektrolysespannung und läßt den gesamten Prozeß,energetisch betrachtet, unwirtschaftlich erscheinen.Alkaline water electrolysis is generally carried out at temperatures below 90 ° C. These relatively low temperatures are necessary because of the low chemical resistance of the commercially used asbestos diaphragms in hot KOH. For reasons of stability, the diaphragms must also be chosen much thicker than would be required for the actual electrolysis. This in turn causes an undesirable high electrolysis voltage and makes the entire process, from an energy perspective, appear uneconomical.
Es wurden daher zahlreiche Versuche unternommen, die Beständigkeit von Asbest in heißer Lauge zu verbessern bzw. andere Diaphragmenmaterialien zu finden. Letzteres ist allerdings sehr schwierig, und bislang ist es, wenn man von einem Separater auf der Basis von Polyantimonsäure (siehe Int. J. Hydrogen Energy 8 (1983), Seiten 81 - 83) absieht, trotz intensiver langjähriger Bemühungen praktisch nicht gelungen, einen geeigneten Ersatz für Asbest zu finden.Numerous attempts have therefore been made to improve the resistance of asbestos in hot lye or to find other diaphragm materials. However, the latter is very difficult, and so far, apart from a separator based on polyantimonic acid (see Int. J. Hydrogen Energy 8 (1983), pages 81-83), despite intensive long-term efforts, one has practically not succeeded to find a suitable replacement for asbestos.
Lediglich von der Anmelderin wurden brauchbare poröse Diaphragmen auf Nickeloxidbasis entwickelt, die durch Oxidation von Sintermetall bei erhöhter Temperatur (DE-OS 29 27 566) oder einfacher durch oxidatives Brennen einer auf einen Träger gepreßten Nickelpulverschicht (DE-OS 30 31 064) erhalten werden. Die chemische Stabilität dieser Diaphragmen wurde weiterhin durch einen bestimmten Gehalt an Titanoxid verbessert (DE-Patentanmeldung P 33 18 758.4-41).Usable porous diaphragms based on nickel oxide have only been developed by the applicant and are obtained by oxidation of sintered metal at elevated temperature (DE-OS 29 27 566) or more simply by oxidative firing of a nickel powder layer pressed onto a support (DE-OS 30 31 064). The chemical stability of these diaphragms was further improved by a certain content of titanium oxide (DE patent application P 33 18 758.4-41).
Diese neuen Diaphragmen auf Nickeloxidbasis besitzen eine ausgezeichnete chemische Beständigkeit in heißer KOH, hervorragende Trenneigenschaften hinsichtlich der beiden Produktgase, 02 und H2, sowie einen außergewöhnlich niedrigen elektrischen Widerstand, der eine energetisch günstige Durchführung der Elektrolyse ermöglicht. Letztere Eigenschaft kommt insbesondere zur Geltung, wenn Elektroden 6 aus dünnem Lochblech oder einer dünnen aktiven porösen Schicht in sog. "Sandwichbauweise unmittelbar mit dem Diaphragma 1 verbunden werden. Mit solchen Elektroden mit "Nullabstand" zum Diaphragma (Fig. 3a) werden Zellspannungen erreicht, die auch sehr hohen energetischen Ansprüchen genügen. Diese sandwichartige Anordnung von Elektroden und Diaphragma, die jeglichen unnötigen zusätzlichen Elektrodenabstand vermeidet, ist energetisch allen bisher kommerziell üblichen Konstruktionen weit überlegen.These new diaphragms based on nickel oxide have an excellent chemical resistance in hot KOH, excellent separation properties with regard to the two product gases, 0 2 and H 2 , as well as an exceptionally low electrical resistance, which is an energetically favorable Carries out the electrolysis. The latter property is particularly effective when electrodes 6 made of thin perforated sheet or a thin active porous layer are connected in a so-called "sandwich construction" directly to the diaphragm 1. With such electrodes having a "zero distance" to the diaphragm (FIG. This sandwich-like arrangement of electrodes and diaphragm, which avoids any unnecessary additional electrode spacing, is far superior in energy terms to all constructions that were customary in the past.
Die industriell üblichen konstruktiven Ausführungen arbeiten allerdings bislang entweder mit jalousieartig ausgebildeten Vollblechen oder einer Art von Streckmetall oder Schlitzblech (Fig. 3b, c). Das hat zur Folge, daß zwischen dem Diaphragma und dem elektrochemisch wirksamen Hauptteil der Elektrode immer eine gewisse Distanz in der Größe von einigen mm besteht, die einen zusätzlichen elektrischen Widerstand darstellt und dadurch zu Energieverlusten im Vergleich zum "Nullabstands"-Konzept führt.Up to now, however, the industrial designs that have been customary in industry have either worked with blind-like solid sheets or a type of expanded metal or slotted sheet (FIG. 3b, c). The result of this is that there is always a certain distance in the size of a few mm between the diaphragm and the electrochemically active main part of the electrode, which represents an additional electrical resistance and thereby leads to energy losses in comparison to the "zero distance" concept.
Die "Sandwichbauweise" hat allerdings auch einen Nachteil, der bei den üblichen energetisch nachteiligeren Konstruktionen nicht auftritt: Das Diaphragma bleibt nur dann funktionsfähig, wenn sich an den Elektroden keine Ablagerungen bilden, die sich dann weiter in das in unmittelbarer Nähe (Nullabstand) befindliche Diaphragma fortpflanzen können. Das setzt natürlich voraus, daß das gesamte Zellsystem samt Peripherie derart korrosionsbeständig sein muß, daß praktisch keine Korrosion stattfindet. Korrosionsprodukte würden sich nämlich infolge der Elektrodenreaktionen entweder kathodisch als Metalle oder anodisch als Oxidhydrate niederschlagen oder abscheiden und von den Elektroden in das Diaphragma hinein übertreten und dieses zusetzen oder sogar zu Kurzschlüssen führen. In der Praxis ist es nun jedoch sehr schwer oder doch zumindest sehr kostspielig, einen korrosionsfreien Zustand aufrechtzuerhalten.However, the "sandwich construction" also has a disadvantage that does not occur with the usual energetically disadvantageous constructions: the diaphragm only remains functional if no deposits form on the electrodes, which can then propagate further into the diaphragm located in the immediate vicinity (zero distance). Of course, this presupposes that the entire cell system including its periphery must be so corrosion-resistant that practically no corrosion takes place. Corrosion products would, as a result of the electrode reactions, either deposit or deposit cathodically as metals or anodically as hydrated oxides and pass from the electrodes into the diaphragm and clog it or even lead to short circuits. In practice, however, it is very difficult or at least very expensive to maintain a corrosion-free state.
D.h., die einerseits energetisch günstige und damit wirtschaftliche Verminderung der Elektrodenabstände ist mit dem Zwang zu kostspieligen Anlagen verbunden, während die konstruktiv billigere mit merklichem Abstand Diaphragma-Elektroden arbeitende Lösung energetisch nachteilig ist.In other words, the energy-saving and thus economical reduction of the electrode spacing on the one hand is associated with the need for expensive systems, while the structurally cheaper solution working with a noticeable distance between the diaphragm electrodes is energetically disadvantageous.
Es ist daher die Aufgabe der Erfindung, hier Abhilfe zu schaffen, d.h. eine konstruktive Lösung zu finden, bei der die Energieverluste aufgrund des Abstandes Diaphragma-Elektroden gering sind, aber trotzdem für Zelle und Peripherie Konstruktionsmaterialien verwendet werden können, die bei tragbarem Preis einigermaßen korrosionsbeständig sind, ohne jedoch jede Korrosion ausschließen zu müssen.It is therefore the object of the invention to remedy this, ie to find a constructive solution in which the energy losses due to the distance between the diaphragm electrodes are small, but nevertheless for the cell and periphery construct tion materials can be used that are reasonably corrosion-resistant at a reasonable price, but without having to rule out any corrosion.
Dieses Ziel wird gemäß der Erfindung mit einem Diaphragma der eingangs genannten Art erreicht, das gekennzeichnet ist durch über die Fläche verteilte in die feinporöse Schicht integrierte aus der Oberfläche vorragende gröbere Körner auf einer oder beiden Seiten des Diaphragmas.This object is achieved according to the invention with a diaphragm of the type mentioned at the outset, which is characterized by coarser grains which protrude from the surface and are distributed over the surface and which protrude from the surface on one or both sides of the diaphragm.
Vorzugsweise umfaßt das Diaphragma einen gerüstgebenden Träger für die feinporöse Schicht, der insbesondere durch ein aufoxidiertes Metallnetz gebildet wird, das die Handhabung auch großflächiger, dünner Diaphragmen zuläßt.The diaphragm preferably comprises a framework for the fine-porous layer, which is formed in particular by an oxidized metal net, which also allows the handling of large, thin diaphragms.
Das erfindungsgemäße Diaphragma umfaßt speziell eine feinporöse Schicht, die durch Oxidation von Sintermetall oder gepreßtem Metallpulver auf Nickelbasis bis zur Erzielung einer ausreichend elektrisch isolierenden Schicht, insbesondere an oder auf einem anoxidierten Metallnetzträger gebildet ist, wobei die aus der Schicht vorragenden gröberen Körner aus aufoxidiertem Metall- oder Metalloxid bestehen.The diaphragm according to the invention specifically comprises a fine-porous layer which is formed by oxidation of sintered metal or pressed metal powder based on nickel until a sufficiently electrically insulating layer is obtained, in particular on or on an oxidized metal mesh support, the coarser grains of oxidized metal protruding from the layer. or metal oxide.
Bei einem solchen "feingenoppten" Diaphragma wird durch die aus der Oberfläche vorragenden gröberen Körner ein gewisser minimaler Abstand zwischen dem eigentlichen feinporigen Diaphragma und einer unmittelbar aufgebrachten elektrolyt- und gasdurchlässigen Elektrode aus Lochblech o.dgl. aufrechterhalten, so daß die Funktion des Diaphragmas auch über längere Zeiten hinweg selbst unter nicht absolut korrosionsfreien Bedingungen der Elektrolysezelle erhalten bleibt, wobei jedoch der (über die Korngröße und den vorragenden Teil der Körner einstellbare) Abstand der Elektrode von der feinporigen Diaphragmaschicht so gering ist, daß keine erheblichen Energieverluste auftreten.In the case of such a "fine-nubbed" diaphragm, the coarser grains protruding from the surface make it somewhat minimal Distance between the actual fine-pored diaphragm and an immediately applied electrolyte- and gas-permeable electrode made of perforated plate or the like. maintained so that the function of the diaphragm is maintained even over longer times even under conditions of the electrolysis cell that are not absolutely corrosion-free, although the distance between the electrode (adjustable via the grain size and the protruding part of the grains) from the fine-pored diaphragm layer is so small, that there are no significant energy losses.
Vorzugsweise haben die gröberen Körner einen Durchmesser von etwa 10 bis 250 µm, insbesondere einen solchen von 50 bis 150 µm, und sie ragen vorzugsweise zu etwa 50 bis 70 % aus der Oberfläche hervor. Sie sind relativ dünn (und üblicherweise wahllos) über die Oberfläche verteilt, da Stabilität und Dicke der Elektrode allgemein ein "Durchsacken" zwischen den Auflagepunkten verhindern, die damit relativ weit auseinander liegen können.The coarser grains preferably have a diameter of about 10 to 250 μm, in particular one of 50 to 150 μm, and they preferably protrude from the surface by about 50 to 70%. They are relatively thin (and usually indiscriminately) distributed over the surface, since the stability and thickness of the electrode generally prevent "sagging" between the contact points, which can therefore be relatively far apart.
Zweckmäßigerweise wird der mittlere Abstand der gröberen Körner etwa bis zum 100fachen des Korndurchmessers gewählt, wobei Kornabstände im Bereich vom 10- bis 50fachen des Korndurchmessers bevorzugt sind.The average distance between the coarser grains is expediently chosen to be up to 100 times the grain diameter, grain spacings in the range from 10 to 50 times the grain diameter being preferred.
Die in die feinporöse Diaphragmaschicht integrierten gröberen Körner bestehen aus aufoxidiertem Metall und werden bei der Diaphragmaherstellung in die Schicht "eingebacken". Zweckmäßigerweise werden daher für die Herstellung Grobkornpulver aus Eisen, Kobalt, Nickel oder Gemischen derselben verwendet.The coarser grains integrated in the fine-porous diaphragm layer consist made of oxidized metal and are "baked" into the layer during the manufacture of the diaphragm. It is therefore expedient to use coarse-grained powders made of iron, cobalt, nickel or mixtures thereof for the production.
Die Herstellung des Diaphragmas erfolgt zweckmäßigerweise, indem man auf die feinporige Schicht des eigentlich wriksamen Diaphragmas ein weiteres Metall-oder Oxidpulver mit gröberem Korn entlang der Oberfläche, oxidativ aufsintert. Hierbei wird insbesondere zunächst in einer ersten Stufe ein feinkörniges Metallpulver (Korngröße ca. 1 bis 5 µm) auf einem Netz als Träger insbesondere auf einem Nickelnetzträger mittels eines Preß- oder Walzvorgangs verdichtet und auf diese so entstandene feinporige Metallpulverschicht erneut ein Metallpulver mit gröberer Korngröße (10 bis 250 µm) dünn verteilt und anschließend . (mit geringer Druckanwendung) eingepreßt oder eingewalzt. Dadurch wird das gröbere Metallpulver in die feinporige Schicht vorläufig eingebettet und fixiert. Auf diese Weise entstehen über die Oberfläche der feinporigen Schicht hinausragende kleine "Noppen". Diese Anordnung wird in einem weiteren Schritt oxidativ gebrannt, so daß die Metallstruktur weitgehend in ein oxidisches Diaphragma umgewandelt wird.The diaphragm is expediently produced by oxidatively sintering a further metal or oxide powder with a coarser grain along the surface onto the fine-pore layer of the actually writable diaphragm. Here, in a first stage in particular, a fine-grained metal powder (grain size approx. 1 to 5 µm) is compacted on a mesh as a carrier, in particular on a nickel mesh carrier, by means of a pressing or rolling process, and a metal powder with a coarser grain size is again applied to this fine-pored metal powder layer 10 to 250 µm) thinly distributed and then. (with little pressure application) pressed or rolled. As a result, the coarser metal powder is temporarily embedded and fixed in the fine-pored layer. In this way, small "knobs" protrude beyond the surface of the fine-pored layer. This arrangement is fired oxidatively in a further step, so that the metal structure is largely converted into an oxidic diaphragm.
Weitere Besonderheiten gehen aus den Patentansprüchen hervor.Further special features emerge from the patent claims.
Der allgemeine Aufbau wird durch die Zeichnungen erläutert; es zeigen schematisch
- Figur 1 ein erfindungsgemäßes Diaphragma mit Elektroden;
- Figur 2 Kurven für die Stromdichte in Abhängigkeit von der Spannung und
- Figur 3 bekannte Anordnungen von Diaphragma und Elektroden.
- 1 shows a diaphragm according to the invention with electrodes;
- Figure 2 curves for the current density as a function of voltage and
- Figure 3 known arrangements of diaphragm and electrodes.
Figur 1 zeigt schematisch den Aufbau des Diaphragmas 1 mit einer feinporösen Schicht 2 auf einem netzartigen Träger 3. In die feinporöse Schicht 2 sind aufoxidierte gröbere Körner 4 mit Zwischenraum 5 eingebakken.FIG. 1 schematically shows the structure of the diaphragm 1 with a fine-porous layer 2 on a mesh-like carrier 3. Coarser grains 4 which have been oxidized on are coagulated into the fine-porous layer 2 with a space 5 between them.
Auf das so ausgebildete (ein- oder beidseitig mit "Noppen" versehene) Diaphragma werden gas- und elektrolytdurchlässige Elektroden 6 (z.B. Lochblech oder poröse, galvanisch erzeugte dünne Elektroden) aufgelegt, die durch die "Noppen" von dem eigentlichen Diaphragma (feinporige Schicht) ferngehalten werden.Gas and electrolyte-permeable electrodes 6 (for example perforated sheet metal or porous, galvanically produced thin electrodes) are placed on the diaphragm formed in this way (provided with “knobs” on one or both sides), which are separated from the actual diaphragm (fine-pored layer) by the “knobs”. be kept away.
Zweckmäßigerweise werden für die Herstellung des Diaphragmas Nickelpulver und ein Nickelträger verwendet und für die "Noppen" Grobkornpulver von Metallen, die aufgrund einer vergleichbaren Wärmeentwicklung während des Oxidationsvorganges zusammen mit der Preß- und Sinterschicht oxidabel und dabei in die feinporöse Schicht integrierbar sein sollen.Advantageously, nickel powder and a nickel carrier are used for the manufacture of the diaphragm and coarse-grain powder of metals for the "knobs", which is produced on the basis of comparable heat development should be oxidizable during the oxidation process together with the press and sintered layer and should be able to be integrated into the fine-porous layer.
Die Preßdrucke für die Herstellung des Diaphragmas richten sich nach der gewünschten Porosität und der Einbettiefe der gröberen Körner, wobei auf alle Fälle eine ungebrannt handhabbare Schicht entstehen soll.The pressure for the manufacture of the diaphragm depends on the desired porosity and the embedding depth of the coarser grains, whereby an unburnt layer should be created in all cases.
Am linken Rand von Figur 1 sind bevorzugte Abmessungen angegeben und man sieht, daß der Abstand der Elektrode vom eigentlichen Diaphragma stufenlos bis auf insbesondere 200 µm je nach Korngröße und Einpreßdruck beim Aufbringen der gröberen Körner variabel gehalten werden kann. Dadurch entfernt sich die feinporöse Diaphragmastruktur aus der direkten Reichweite der Elektrode nur so weit, wie es zum Vermeiden der schädlichen Nebenwirkungen der Elektroden auf das Diaphragma während des Elektrolysebetriebs notwendig ist, wobei die vorteilhaften geringen Elektrodenabstände weiter erhalten bleiben.Preferred dimensions are given on the left-hand edge of FIG. 1 and it can be seen that the distance of the electrode from the actual diaphragm can be kept variable up to in particular 200 μm, depending on the grain size and injection pressure when the coarser grains are applied. As a result, the fine-porous diaphragm structure is removed from the direct range of the electrode only as far as is necessary to avoid the harmful side effects of the electrodes on the diaphragm during electrolysis operation, the advantageous small electrode spacing being retained.
D.h., die mit am Diaphragma anliegenden Elektroden erzielbaren niedrigen Zellspannungen bleiben praktisch erhalten (Fig. 2), und gleichzeitig können schädliche Metallablagerungen, unerwünschte chemische Einwirkungen der Elektrolyseprodukte und Zwischenprodukte auf das Diaphragma bzw. eine direkte Beeinflussung des Diaphragmas durch die Elektroden selbst oder eine zu intensive Diffusion durch das Diaphragma hindurch weitgehend vermieden werden.This means that the low cell voltages that can be achieved with electrodes lying on the diaphragm are practically retained (FIG. 2), and at the same time harmful metal deposits, undesirable chemical effects of the electrolysis products and intermediate products on the diaphragm or direct influencing of the diaphragm by the electrodes themselves or excessive diffusion through the diaphragm are largely avoided.
In diesem Zusammenhang ist sehr wichtig zu betonen, daß die auf die beschriebene Art gebildeten "Mikrospacer" oder "Noppen" keine hydrophoben Eigenschaften besitzen und dadurch insbesondere für gasentwickelnde elektrochemische Vorgänge von Vorteil sind, da keine schädlichen Nebenwirkungen durch den sog. Blasenvorhangseffekt auf die Zellspannung auftreten können.In this context it is very important to emphasize that the "microspacers" or "knobs" formed in the manner described have no hydrophobic properties and are therefore particularly advantageous for gas-developing electrochemical processes since there are no harmful side effects due to the so-called bubble curtain effect on the cell voltage may occur.
Es folgt ein Beispiel für die Herstellung eines erfindungsgemäßen Diaphragmas:The following is an example of the manufacture of a diaphragm according to the invention:
Mit Hilfe eines Kunststoffsiebes (Siebdruckverfahren, Bespannung PES 12 - 15) wurde trockenes Nickelpulver,INCO(R) 255, gleichmäßig auf einer Metallplatte verteilt.With the help of a plastic sieve (screen printing process, covering PES 12 - 15), dry nickel powder, INCO ( R ) 255, was evenly distributed on a metal plate.
Die Schichtstärke lag bei 40 mg/cm2. Darüber wurde ein Nickelnetz mit einer Maschenweite von 0,20 mm und einer Drahtstärke von 0,125 mm gelegt und das Ganze mit einem Preßdruck von ca. 200 N/cm2 kaltverdichtet. Auf diese Weise erhältThe layer thickness was 40 mg / cm 2 . A nickel mesh with a mesh size of 0.20 mm and a wire thickness of 0.125 mm was placed over it and the whole was cold-compressed with a pressure of approx. 200 N / cm 2 . That way
man einen (ungebrannten) Vorkörper in Form eines Nickelnetzträgers mit einseitiger Pulverschicht.a (unfired) preform in the form of a nickel mesh support with a powder layer on one side.
Die Verfahrensweise wurde wiederholt unter Erzielung eines handhabbaren Vorkörpers aus beidseits beschichtetem Nickelnetz.The procedure was repeated to obtain a manageable preform made of nickel mesh coated on both sides.
Über eine Metallplatte wurde dann Eisenpulver mit einer Korngröße von 10D bis 150 µm gleichmäßig in einer Flächendichte von 10 mg/cm2 verteilt. Auf diese Schicht wurde der Diaphragma-Vorkörper gelegt und unter leichtem Druck (ca. 10 N/cm2) hineingepreßt. Die zweite Seite wurde analog behandelt.Iron powder with a grain size of 10D to 150 μm was then uniformly distributed over a metal plate in a surface density of 10 mg / cm 2 . The diaphragm preform was placed on this layer and pressed in under slight pressure (approx. 10 N / cm 2 ). The second page was treated analogously.
Dieser Vorkörper wurde dann 15 Minuten lang in Luft in einem Ofen von 1000 °C oxidativ gesintert, wodurch ein für den Einbau in eine Elektrolysezelle mit anliegenden Elektroden geeignetes Diaphragma mit "Mikrospacern" erhalten wurde.This preform was then oxidatively sintered in air in a furnace at 1000 ° C. for 15 minutes, whereby a diaphragm with “microspacers” suitable for installation in an electrolysis cell with adjacent electrodes was obtained.
Die chemische Beständigkeit dieses Diaphragmas unterscheidet sich nicht von derjenigen eines reinen NiO-Diaphragmas gemäß der DE-OS 3 031 064 ohne "Mikrospacer", d.h., das neue Diaphragma ist für einen Langzeitbetrieb unte: Elektrolysebedingungen sehr gut geeignet.10The chemical resistance of this diaphragm does not differ from that of a pure NiO diaphragm according to DE-OS 3 031 064 without a "micro spacer", i.e. the new diaphragm is very suitable for long-term operation under: electrolysis conditions. 10
Claims (12)
dadurch gekennzeichnet, daß die gröberen Körner (4) einen Durchmesser von etwa 10 bis 250 µm, insbesondere 50 bis 150 µm, haben.4. Diaphragm according to one of the preceding claims,
characterized, that the coarser grains (4) have a diameter of about 10 to 250 microns, especially 50 to 150 microns.
dadurch gekennzeichnet, daß die gröberen Körner (4) einen mittleren Abstand bis zum etwa 100fachen ihres Korndurchmessers haben.5. diaphragm according to one of the preceding claims,
characterized in that the coarser grains (4) have an average distance up to about 100 times their grain diameter.
daß die Körner (4) zu etwa 50 bis 70 % aus der Oberfläche hervorragen.7. diaphragm according to one of the preceding claims,
that the grains (4) protrude about 50 to 70% from the surface.
gekennzeichnet durch vorragende gröbere Körner (4) aus aufoxidiertem Fe, Co, Ni oder Gemischen derselben, die aus einer feinporösen Nickeloxidschicht mit einem anoxidierten Nickelnetzträger vorragen.8. diaphragm according to one of the preceding claims,
characterized by protruding coarser grains (4) made of oxidized Fe, Co, Ni or mixtures thereof, which protrude from a fine porous nickel oxide layer with an oxidized nickel mesh support.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE19843424203 DE3424203A1 (en) | 1984-06-30 | 1984-06-30 | DIAPHRAGMA FOR ALKALINE ELECTROLYSIS AND METHOD FOR PRODUCING THE SAME |
DE3424203 | 1984-06-30 |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0170051A2 true EP0170051A2 (en) | 1986-02-05 |
EP0170051A3 EP0170051A3 (en) | 1986-06-25 |
Family
ID=6239568
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP85107908A Withdrawn EP0170051A3 (en) | 1984-06-30 | 1985-06-26 | Diaphragm for alkaline electrolysis, and its manufacturing process |
Country Status (6)
Country | Link |
---|---|
US (1) | US4636291A (en) |
EP (1) | EP0170051A3 (en) |
JP (1) | JPS6144191A (en) |
DE (1) | DE3424203A1 (en) |
NO (1) | NO852601L (en) |
ZA (1) | ZA854894B (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0206032A1 (en) * | 1985-06-12 | 1986-12-30 | Forschungszentrum Jülich Gmbh | Electrolyser with a diaphragm electrode sandwich assembly, and assembling apparatus suited therefor |
Families Citing this family (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
ES2118088T3 (en) * | 1990-07-06 | 1998-09-16 | Igr Ets Inc | DUCTILE CERAMIC COMPOUNDS. |
US5332483A (en) * | 1990-07-06 | 1994-07-26 | Igr Enterprises, Inc. | Gas separation system |
US6592965B1 (en) | 1990-07-06 | 2003-07-15 | Igr Enterprises, Inc. | Ductile ceramic composite electrolyte |
US6071635A (en) * | 1998-04-03 | 2000-06-06 | Plug Power, L.L.C. | Easily-formable fuel cell assembly fluid flow plate having conductivity and increased non-conductive material |
US6007933A (en) * | 1998-04-27 | 1999-12-28 | Plug Power, L.L.C. | Fuel cell assembly unit for promoting fluid service and electrical conductivity |
US8808512B2 (en) | 2013-01-22 | 2014-08-19 | GTA, Inc. | Electrolyzer apparatus and method of making it |
US9222178B2 (en) | 2013-01-22 | 2015-12-29 | GTA, Inc. | Electrolyzer |
US11248303B2 (en) | 2018-06-06 | 2022-02-15 | Molecule Works Inc. | Electrochemical device comprising thin porous metal sheet |
WO2022167880A1 (en) * | 2021-02-04 | 2022-08-11 | CTS H2 S.r.l. | Particularly compact and efficient assembly with separator and electrodes to be used in the electrolysis of water for the production of hydrogen at high pressure |
Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0061080A1 (en) * | 1981-03-24 | 1982-09-29 | Asahi Glass Company Ltd. | Ion exchange membrane electrolytic cell |
Family Cites Families (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US1082286A (en) * | 1912-10-02 | 1913-12-23 | Niagara Alkali Company | Diaphragm for electrolytic apparatus. |
US4073999A (en) * | 1975-05-09 | 1978-02-14 | Minnesota Mining And Manufacturing Company | Porous ceramic or metallic coatings and articles |
US4032427A (en) * | 1975-11-03 | 1977-06-28 | Olin Corporation | Porous anode separator |
DE2927566C2 (en) * | 1979-07-07 | 1986-08-21 | Kernforschungsanlage Jülich GmbH, 5170 Jülich | Diaphragm for alkaline electrolysis, process for producing the same and its use |
JPS5693883A (en) * | 1979-12-27 | 1981-07-29 | Permelec Electrode Ltd | Electrolytic apparatus using solid polymer electrolyte diaphragm and preparation thereof |
DE3031064C2 (en) * | 1980-08-16 | 1986-09-04 | Kernforschungsanlage Jülich GmbH, 5170 Jülich | Porous oxide diaphragm for alkaline electrolysis and its use |
US4476002A (en) * | 1982-06-29 | 1984-10-09 | Union Carbide Corporation | Metal current carrier for electrochemical cell electrodes |
US4457832A (en) * | 1983-01-19 | 1984-07-03 | Chevron Research Company | Combination catalytic reforming-isomerization process for upgrading naphtha |
DE3318758C2 (en) * | 1983-05-24 | 1985-06-13 | Kernforschungsanlage Jülich GmbH, 5170 Jülich | Nickel oxide based diaphragm and method of making the same |
-
1984
- 1984-06-30 DE DE19843424203 patent/DE3424203A1/en not_active Withdrawn
-
1985
- 1985-06-26 EP EP85107908A patent/EP0170051A3/en not_active Withdrawn
- 1985-06-27 JP JP60139215A patent/JPS6144191A/en active Pending
- 1985-06-28 NO NO852601A patent/NO852601L/en unknown
- 1985-06-28 ZA ZA854894A patent/ZA854894B/en unknown
- 1985-07-01 US US06/750,858 patent/US4636291A/en not_active Expired - Fee Related
Patent Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0061080A1 (en) * | 1981-03-24 | 1982-09-29 | Asahi Glass Company Ltd. | Ion exchange membrane electrolytic cell |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0206032A1 (en) * | 1985-06-12 | 1986-12-30 | Forschungszentrum Jülich Gmbh | Electrolyser with a diaphragm electrode sandwich assembly, and assembling apparatus suited therefor |
Also Published As
Publication number | Publication date |
---|---|
ZA854894B (en) | 1986-03-26 |
US4636291A (en) | 1987-01-13 |
DE3424203A1 (en) | 1986-01-16 |
NO852601L (en) | 1986-01-02 |
EP0170051A3 (en) | 1986-06-25 |
JPS6144191A (en) | 1986-03-03 |
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