EP0004191A2 - Chloralkali Elektrolysezelle und Verfahren zu deren Betrieb - Google Patents

Chloralkali Elektrolysezelle und Verfahren zu deren Betrieb Download PDF

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EP0004191A2
EP0004191A2 EP79300369A EP79300369A EP0004191A2 EP 0004191 A2 EP0004191 A2 EP 0004191A2 EP 79300369 A EP79300369 A EP 79300369A EP 79300369 A EP79300369 A EP 79300369A EP 0004191 A2 EP0004191 A2 EP 0004191A2
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Prior art keywords
oxygen
compartment
cathode
anode
electrolytic cell
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French (fr)
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EP0004191B1 (de
EP0004191A3 (en
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Ronald Lowry Labarre
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Eltech Systems Corp
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Eltech Systems Corp
Diamond Shamrock Corp
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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
    • C25B1/00—Electrolytic production of inorganic compounds or non-metals
    • C25B1/01—Products
    • C25B1/34—Simultaneous production of alkali metal hydroxides and chlorine, oxyacids or salts of chlorine, e.g. by chlor-alkali electrolysis
    • C25B1/46—Simultaneous production of alkali metal hydroxides and chlorine, oxyacids or salts of chlorine, e.g. by chlor-alkali electrolysis in diaphragm cells

Definitions

  • the present invention relates generally to the operation of an oxygen electrode for use in an electrolytic cell and particularly for the production of chlorine and caustic (sodium hydroxide) in such a manner as to significantly reduce the voltages necessary for the operation of such electrolytic cells and to increase substantially the power efficiencies available from such electrolytic cells utilizing oxygen electrodes.
  • the present disclosure relates to improved methods of operation of oxygen electrodes which include utilizing a positive air to liquid pressure drop on the air feed side of the oxygen electrode to improve performance, control of the total flow of the gas feed stream to improve the mass transfer within the air feed side of the oxygen electrode at the reaction sites, humidification of the gas feed to the oxygen electrodes to reduce the drying out and delamination of the oxygen electrode so that it might function at a higher current density over a longer lifetime, and the elimination of certain gases such as carbon dioxide to increase the lifetime of the oxygen electrodes by elimination of salts which might be formed upon the porous structure of the oxygen electrode during the use thereof.
  • These methods of operation may be utilized singularly or preferably in combination to produce higher power efficiencies at lower voltages so as to produce a more energy- efficient oxygen electrode in an electrolytic cell especially suitable for the production of chlorine and caustic (sodium hydroxide).
  • Chlorine and caustic are essential large volume commodities which are basic chemicals required by all industrial societies. They are produced almost entirely electrolytically from aqueous solutions of alkaline metal halides or more particularly sodium chloride with a major portion of such production coming from diaphragm type electrolytic cells.
  • brine sodium chloride solution
  • a diaphragm usually made of asbestos particles formed over a cathets strocture of a foraminous nature To minimize back migration of the hydroxide ions, the flow rate is always maintained in excess 01 the conversion rate so that the resulting catholyte solution has unused or unreacted sodium chloride present.
  • the hydrogen ions are discharged from the solution at the cathode in the form of hydrogen gas.
  • the catholyte solution containing caustic soda (sodium hydroxide), unreacted sodium chloride and other impurities, must then be concentrated and purified to obtain a marketable sodium hydroxide commodity and sodium chloride which is to be reused in electrolytic cells for further production of sodium hydroxide and chlorine.
  • the evolution of the hydrogen gas utilizes a higher voltage so as to reduce the power efficiency possible from such an electrolytic cell thus creating an energy inefficient means of producing sodium hydroxide and chlorine gas.
  • the electrolytic cell With the advent of technological advances such as dimensionally stable anodes and various coating compositions therefore which permit ever narrowing gaps between the electrodes, the electrolytic cell has become more efficient in that the power efficiency is greatly enhanced by the use of these dimensionally stable anodes. Also, the hydraulically impermeable membrane has added a great deal to the use of the electrolytic cells in terms of selective migration of various ions across the membrane so as to exclude contaminates from the resultant product thereby eliminating some of the costly purification and concentration steps of processing.
  • the oxygen electrode presents one possibility of elimination of this reaction since it consumes electrochemically activated oxygen to combine with water and the electrons available at the cathode in accordance with the following equation It is readily apparent that this reaction is more energy efficient by the very absence of the production of any hydrogen at the cathode, and the reduction in potential as shown above.
  • This is accomplished by feeding an oxygen rich fluid such as air or oxygen to an oxygen side of an oxygen electrode where the oxygen has ready access to the electrolytic surface so as to be consumed in the fashion according to the equation above.
  • This does, however, require a slightly different structure for the electrolytic cell itself so as to provide for an oxygen compartment on the cathodic side of the cathode so that the oxygen rich substance may be fed thereto.
  • the oxygen electrode itself is well known in the art since the many NASA projects utilized to promote space travel during the 1960s also provided funds for the development of a fuel cell utilizing an oxygen electrode and a hydrogen anode such that the gas feeding of hydrogen and oxygen would produce an electrical current for utilization in a space craft. While this major government-financed research effort produced many fuel cell components including an oxygen electrode the circumstances and the environment in which the oxygen electrode was to function were quite different from that which would be experienced in a chlor-alkali cell. Thus while much of the technology gained during the NASA projects is of vaiue in the chlor-alkali industry with regard to development of an oxygen electrode, much further development is necessary to adapt the oxygen electrode to the chlor-alkali cell environment.
  • a chlor-alkali electrolytic cell having an anode compartment, a cathode compartment divided from the anode compartment by a separator and an oxygen compartment divided from the cathode compartment by an oxygen electrode can be operated by a method comprising the steps of: needing an alkali metal halide solution to the interior of the anode compartment; feeding an aqueous solution to the interior of the cathode compartment; feeding a molecular oxygen containing fluid to the interior of the oxygen compartment at a positive gauge pressure; so as to accomplish a total flowrate in excess of the theoretical stoichiometric amount of oxygen necessary for the reaction; applying an electrical potential between the cathode and anode of the electrolytic cell; removing halogen gas from the anode compartment; removing alkali metal hydroxide from the cathode compartment; and removing an oxygen depeleted fluid from the oxygen compartment while maintaining the positive gauge pressure upon the interior of the oxygen compartment.
  • a chlor-alkali electrolytic cell having an anode compartment, a cathode compartment divided from the anode compartment by a separator and an oxygen compartment divided from the cathode compartment by an oxygen electrode can be operated by a method comprising the steps of: feeding an alkali metal halide solution to the interior of the anode compartment; feeding an aqueous solution to the interior of the cathode compartment; feeding a molecular oxygen containing carbon dioxide depleted gas having a high humidity content to the interior of the oxygen compartment; applying an electrical potential between the cathode and anode of the electrolytic cell; removing the halogen gas from the anode compartment; removing the alkali metal hydroxide from the cathode compartment; and removing the oxygen depleted humidified gas from the oxygen compartment.
  • a chlor-alkali electrolytic cell for the production of chlorine and alkali metal hydroxide comprising: an anode compartment adapted to contain an anolyte containing an alkali metal chloride; a cathode compartment adapted to contain a catholyte containing an alkali metal hydroxide and divided from said anode compartment by a separator; a separator; an oxygen compartment adopted to receive an oxygen containing fluid, free of carbon dioxide, humidified, at a positive gauge pressure, and at a positive total flow of from 1.5 to 10 times the stoichiometric amount of oxygen; an oxygen electrode dividing said cathode compartment from said oxygen compartment; means for controlling the moisture content of the oxygen containing substance; means for controlling the pressure of the oxygen containing fluid within said oxygen compartment; means for controlling the total flowrate of the oxygen containing fluid within said oxygen compartment; means for removing chlorine from said anode compartment; means for removing alkali metal hydroxide from said cathode compartment; means for supplying al
  • Electrolytic cell 12 refers to a monopolar divided electrolytic cell which is suitable for use according to the concepts of the present invention.
  • Electrolytic cell 12 would generally have some environmental supporting structure or foundation to maintain each electrolytic cell 12 in correct alignment so as to build a bank of electrolytic cells for production purposes. The details of this environmental structure have not been shown for ease of illustrating the concepts of the present invention.
  • the cell itself could be manufactured from various materials either metallic or plastic in nature as long as these materials resist the caustic surroundings of the chlorine environment, and temperature characteristics during the operation of the basic chlor-alkali cell which are well known in the art.
  • materials generally include but are not limited to metallic materials such as steel, nickel, titanium and other valve metals in addition to plastics such as polyvinylchloride, polyethylene, polypropylene, fiberglas and others too numerous to mention.
  • the valve metals include aluminum, molybdenum, niobium, titanium, tungsten, zirconium and alloys thereof.
  • the electrolytic cell 12 shown has an anode 14, a separator 16, and a cathode 18 such that three individual compartments are formed within the electrolytic cell being mainly the anode compartment 20, the cathode compartment 22, and the oxygen compartment 24.
  • the anode 14 will generally be constructed of a metallic substance, although graphitic carbon could be used as in the old electrodes which have largely been discarded by the industry presently. These anodes, particularly if they are to be used in a chlor-alkali cell 12, would generally be active material resistant to the anolyte such as a valve metal.
  • a preferred valve metal based upon cost, availability and electrical chemical properties is titanium.
  • a titanium substrate may take in the manufacture of an electrode, including for example, solid metal sheet material; expanded metal mesh material with a large percentage open area, and a porous titanium with a density of 30 to 70 percent pure titanium which can be produced by cold compacting titanium powder. Porous titanium seems to be the preferred substance presently for its long life characteristics along with its relative structural integrity. If desired, the porous titanium can be reinforced with titanium mesh in the case of large electrodes.
  • these substrate materials will have a surface coating to protect the material against passivation such as to make same what is generally known in the art as a dimensionally stable anode.
  • Most of these coatings contain a noble metal, a noble metal oxide either alone or in combination with a valve metal oxide or other electrocatalytically active corrosion-resistant materials.
  • These so-called dimensionally stable anodes are well-known and are widely used in the industry.
  • One type of coating for instance would be a Beer-type coating which can be seen from U.S. Patent Numbers: 3,236,756; 3,623,493; 3,711,385; 3,751,296; and 3,933,616.
  • Another type of coating utilized is one which tin, titanium and ruthenium oxides are used for surface coating as can be seen in U.S. Patent Numbers 3,776,834 and 3,855,092.
  • Two other examples of surface coatings include a tin, antimony with titanium and ruthenium oxides as found in U.S. Patent Number 3,875,043 and a tantalium iridium oxide coating as found in U.S. Patent Number 3,878,083.
  • coatings which are available to those skilled in the art for use in chlor-alkali cells as well as other types of applications in which electrodes would be necessary for electrolytic reactions.
  • the fluorinated copolymer is derived from monomers of the formulas: in which the pendant -S0 2 F groups are converted to -S0 3 H groups, and monomers of the formula wherein R represents the group -CF- CF2 -0- ( ⁇ CFY-CF 2 - O) ⁇ m in which the R 1 is fluorine or fluoroalkyl of 1 thru 10 carbon atoms; Y is fluorine or trifluoromethyl; m is 1, 2 or 3; n is O or 1; X is fluorine, chlorine or trifluoromethyl; and X is X or CF 3 ( ⁇ CF 2 ) ⁇ a 0- , wherein a is O or an integer from 1 to 5.
  • copolymer there should be sufficient repeating units, according to formula (3) above, to provide an -SO 3 H equivalent weight of about 800 to 1600.
  • Materials having a water absorption of about 25 percent or greater are preferred since higher cell voltages at any given current density are required for materials having less water absorption.
  • materials having a film thickness (unlaminated) of about 8 mils or more require higher cell voltages resulting in a lower power efficiency.
  • the substrate film material will be laminated to and impregnated onto a hydraulically permeable, electrically non-conductive, inert, reinforcing member such as a woven or non-woven fabric made of fibers of asbestos, glass, TEFLON, or the like.
  • a hydraulically permeable, electrically non-conductive, inert, reinforcing member such as a woven or non-woven fabric made of fibers of asbestos, glass, TEFLON, or the like.
  • the laminating produce an unbroken surface of the film resin on at least one side of the fabric to prevent leakage through the substrate film material.
  • Polymeric materials can also be made wherein the ion exchange group instead of being a sulfonic acid exchange group could be many other types of structures.
  • One particular type of structure is a carboxyl group ending in either an acid, and ester or a salt to form an ion exchange group similar to that of the sulfonic acid.
  • R 2 may be selected from the group of hydrogen, an alkali metal ion or an organic radical.
  • a substrate material such as NAFION having any ion exchange group or function group capable of being converted into an ion exchange group or a function group in which an ion exchange group can easily be introduced would include such groups as oxy acids, salts, or esters of carbon, nitrogen, silicon, phosphorous, sulfer chlorine, arsenic, selenium, or tellurium.
  • a second type of substrate material has a backbone chain of copolymers of tetrafluoroethylene and hexafluoropropylene and, grafted onto this backbone, a fifty-fifty mixture of styrene and alpha-methyl styrene. Subsequently, these grafts may be sulfonated or carbonated to achieve the ion exchange characteristic.
  • This type of substrate while having different pendant groups has a fluorinated backbone chain so that the chemical resistivities are reasonably high.
  • substrate film material would be polymeric substances having pendant carboxylic or sulfonic acid groups wherein the polymeric backbone is derived from the polymerization of a polyvinyl aromatic component with a monovinyl aromatic component in an inorganic solvent under conditions which prevent solvent evaporation and result in a generally copolymeric substance although a 100 percent polyvinyl aromatic compound may be prepared which is satisfactory.
  • the polyvinyl aromatic component may be chosen from the group including: divinyl benzenes, divinyl toluenes, divinyl napthalenes, divinyl diphenyls, divinyl-phenyl vinyl ethers, the substituted alkyl derivatives therenf such as dimethyl divinyl benzenes and similar polymerizable aromatic compounds which are polyfunctional with respect to vinyl groups.
  • the monovinyl aromatic component which will generally be the impurities present in commercial grades of polyvinyl aromatic compounds include: styrene, isomeric vinyl toluenes, vinyl napthalenes, vinyl ethyl benzenes, vinyl chlorobenzenes, vinyl xylenes, and alpha substituted alky' derivates thereof, such as alpha methyl vinyl benzene.
  • styrene isomeric vinyl toluenes
  • vinyl napthalenes vinyl ethyl benzenes
  • vinyl chlorobenzenes vinyl xylenes
  • alpha substituted alky' derivates thereof such as alpha methyl vinyl benzene.
  • Suitable solvents in which the polymerizable material may be dissolved prior to polymerization should be inert to the polymerization (in that they do not react chemically with the monomers or polymer), should also possess a boiling point greater than 60°C, and should be miscible with the sulfonation medium.
  • Polymerization is effected by any of the well known expedients, fc: instance, heat, pressure, and catalytic accelerators, and is continued until a insoluble, infusible gel is formed substantially throughout the volume of solute
  • fc instance, heat, pressure, and catalytic accelerators
  • the resulting gel structures are then sulfonated in a solvated condition and to such an extent that there are not more than four equivalents of sulfonic acid groups formed for each mole of polyvinyl aromatic compound in the polymer and not less than one equivalent of sulfonic acid groups formed for each ten mole of poly and monovinyl aromatic compound in the polymer.
  • these materials may require reinforcing of similar materials.
  • Substrate film materials of this type are further described in the following patents which are hereby incorporated by reference: U.S. Patent Numbers 2,731,408; 2,731,411 and 3,887,499. These materials are available from Ionics, Inc. under the trademark IONICS CR6.
  • these substrate materials have been sought, one of the most effective of which is the surface chemical treatment of the substrate itself.
  • these treatments consist of reacting the pendant groups with substances which will yield less polar bonding and thereby absorb fewer water molecules by hydrogen bonding. This has a tendency to narrow the pore openings through which the cations travel so that less water of hydration is transmitted with the cations through the membrane.
  • An example of this would be to react the ethylene diamine with the pendant groups to tie two of the pendant groups together by two nitrogen atoms in the ethylene diamine.
  • the surface treatment will be done to a depth of approximately 2 mils on one side of the film by controlling the time of reaction. This will result in good electrical conductivity and cation transmission with less hydroxide ion and associated water reverse migration.
  • the separator 16 could also be a porous diaphragm which may be made of any material compatible with the cell liquor environment, the proper bubble pressure and electrical conductivity characteristics.
  • a material is asbestos which can be used either in paper sheet form or be vacuum-deposited fibers.
  • a further modification can be affected by adding polymeric substances, generally fluorinated, to the slurry from which the diaphragm is deposited.
  • polymeric materials themselves can be made porous to the extent that they show operational characteristics of a diaphragm. Those skilled in the art will readily recognize the wide variety of materials that are presently available for use as separators in chlor-alkali cells.
  • the cathode 18 in order to be utilized according to the methods of the present invention, will necessarily be an oxygen cathode.
  • An oxygen electrode or oxygen cathode may be defined as an electrode which is supplied with a molecular oxygen containing fluid to lower the voltage below that necessary for the evolution of hydrogen.
  • the basic support for an oxygen cathode will generally include a current collector which could be constructed of a base metal although carbon black might also be used.
  • the expression base metal is used herein to refer to inexpensive metals which are commercially available for common construction purposes.
  • Base metals are characterized by low cost, ready availability and adequate resistances to chemical corrosion when utilized as a cathode in electrolytic cells.
  • Base metals would include, for instance, iron, nickel, lead and tin.
  • Base metals also include alloys such as mild steels, stainless steel, bronze, monel and cast iron.
  • the base metal preferably is chemical resistant to the catholyte and has a high electrical conductivity. Furthermore, this material will generally be a slightly porous material such as a mesh when used in the construction of an oxygen cathode.
  • a preferred metal, based upon cost, resistance to the catholyte and voltages available, is nickel.
  • Other current collectors would include: tantalum, titanium, silver, gold, and plated base metals.
  • this basic support material Upon one side of this basic support material will be a coating of a porous material either compacted in such a fashion as to adhere to the nickel support or held together with some kind d binding substance so as to produce a porous substrate material.
  • a preferred porous material based upon cost is carbon.
  • Anchored within the porous portion of the oxygen cathode is a catalyst to catalyze the reaction wherein molecular oxygen combines with water molecules to produce hydroxide groups.
  • catalysts are generally based upon a silver or a platinum group metal such as palladium, ruthenium, gold, iridium, rhodium, osmium, or rhenium but also may be based upon semiprecious or nonprecious metal, alloys, metal oxides or organometal complexes.
  • electrodes will contain a hydrophobic material to wetproof the electrode structure.
  • porosity of the carbon material, the amount and the type of catalytic material used will affect the voltages and current efficiencies of the resultant electrolytic cell as well as their lifetimes.
  • a preferred cathode 18 may be constructed according to U. S. Patent No. 3,423,247, the disclosure of which is hereby incorporated by reference.
  • an electrolytic cell 12 having three compartments, basically an anode compartment 20, a cathode compartment 22 and an oxygen compartment 24.
  • an alkali metal halide solution in the anode compartment 20 as transmitted thereinto through the alkali metal halide solution inlet 26.
  • the alkali metal halide solution preferably would be one which would evolve chlorine gas, such as sodium chloride or potassium chloride.
  • Into the cathode compartment 22 would be found an aqueous solution which would be transmitted thereinto through the aqueous solution inlet 28.
  • the aqueous solution must contain sufficient water molecules to be broken down to form the required hydroxide groups necessary for the reaction.
  • a fluid containing a sufficient amount of molecular oxygen to permit the cell operational characteristics Such a substance would generally be a gas and most preferably would be air with carbon dioxide removed and humidified or pure molecular oxygen which had been humidified.
  • the reaction products such as chlorine gas would be removed from the anode compartment 20 through the halogen outlet 32 and aqueous NaOH or KOH would be removed from the cathode compartment 22 through the alkali metal hydroxide outlet 34 and an oxygen depleted fluid either in the form of residual pure oxygen or air most preferably would be removed from the depleted fluid outlet 36.
  • a pressure differential is applied across the porous cathode 18 so that the pressure in the oxygen compartment 24 is higher than that in the cathode compartment 22.
  • the increased pressure which may be zero gauge to bubble through but due to the electrolyte head may be negative absolute, assists in mass transfer of the oxidizing gas such as oxygen into the cathode 18 thereby preventing oxygen depletion in the reaction zone within the cathode 18 and leading to a longer cathode 18 lifetime.
  • This pressure differential it should be remembered is based upon the partial pressure of the oxygen present if less than 100% oxygen is used.
  • Increasing the total flow of the depolarizing gas in the oxygen compartment 24 also enhances the mass transfer of oxygen into the reaction sites within the cathode 18. This is particularly important where less than 100% pure 0 2 is used.
  • Molecular oxygen is consumed by the reaction taking place at the catalytic sites within the porous material of the oxygen cathode 18. As oxygen is consumed, additional quantities must be available continously and must, therefore, be fed on a continuous basis into the oxygen compartment 24.
  • the preferred total flows are between 0 and 10 times the theoretical stoichiometric amount of oxygen necessary for the reaction with a flow of about 2.5 times being the best.
  • Pure oxygen gas may be supplied to the oxygen compartment 24, however air may also be used since it contains approximately 23% free molecular oxygen by weight.
  • air In the case of air though, carbon dioxide must be removed from the air before it is delivered to the oxygen compartment 24. It has been found that carbon dioxide will promote a formation of certain carbonate deposits upon the cathode which sharply reduces its lifetime and power efficiencies while increasing the voltage. By eliminating the major portion of carbon dioxide this problem was also largely eliminated.
  • the evaporative driving force which causes the mass transfer of the water from the cathode compartment 22 into the cathode structure 18, causes the crystallization of electrolyte to form solids which reduce seriously the lifetime of a given cathode 18 because the solids plug up the pores.
  • the humidification of the feed gas to the oxygen compartment 24 this is drastically reduced by eliminating the evaporative driving force involved in transferring the liquid electrolyte from the cathode compartment 22.
  • a flow of carbon dioxide free air was passed into the oxygen compartment of the cell at a flow rate of approximately 790 cubic centimeters per minute which is approximately 21 times the theoretical stoichiometric amount needed when the cell is operated at 1 ampere per square inch current density.
  • the pressure in the oxygen compartment was adjusted to approximately 110 grams per square centimeter (44 inches of water) above atmospheric pressure by restricting the flow exiting from the outlet 36. The pressure was maintained at that level during the test. Electrolyte consisting of approximately 400 grams NaOH per liter was then added to the cathode compartment 22 and agitated continuously by magnetic stirring apparatusus.
  • the cathode was then conditioned by operating the cell at 60°C. and a current density of approximately 0.05 amperes per square centimeter (one- third ampere per square inch) for about one day. After conditioning was completed, the current density was increased to approximately 0.15 amperes per square centimeter (one ampere per square inch). The air flow, pressure, temperature and current density were held constant during the remainder of the test. It should be noted that these tests were used with sodium hydroxide electrolyte only and as such chlor-alkali cells were not used.
  • the cathodes were conditioned at the reduced current density because it was thought that the catalytic platinum layer becomes partially oxidized, during the period when the cathodes are stored before use.
  • the conditioning process restores the catalytic layer to high activity without causing deterioration in the quality of the cathode. Slow break-in for less noble catalysts however may be harmful.
  • the electrical connection was made on the nickel side of the cathode because it was easier to make a good electrical contact on nickel rather than on the carbon.
  • the cathode reference voltage measured versus a mercury/mercuric oxide reference electrode cell changed from -0.31 on day number 1 to -1.03 on day number 98 when the test was considered completed.
  • the lifetime of this particular cathode under these test conditions was 2350 hours.
  • a cathode test was done as described in Example 1, except that the air flow rate was reduced from 790 cubic centimeters per minute to 220 cubic centimeters per minute (approximately 6 times the theoretical stoichiometric amount necessary for reaction).
  • the reference voltage changed from -0.43 on day number 1 to -2.27 on day number 52.
  • the cathode lifetime was 1240 hours in this test as compared to 2350 when increased air flow was used in Example 1. This shows that when the total flow increases, the potentials are lower and the lifetimes are extended.
  • a cathode test was done as described in Example 1, except that an oxygen flowrate of 150 cubic centimeters per minute was used instead of an air flowrate of 790 cubic centimeters per minute. This oxygen flow rate was about 19 times the theoretical stoichiometric flow of oxygen required at one ampere per square inch current density for operation of a cell. For this test, the electrical connection was made on the carbon side of the cathode.
  • the cathode was conditioned by running the cell at a current density of 0.05 amperes per square centimeter (1/3 ampere per square inch) for about 24Y2 hours, increasing it to 0.1 ampere per square centimeter (2/3 ampere per square inch) for about 24 hours, and finally increasing it to about 0.15 ampere per square centimeter (1 ampere per square inch) at which level it was held for the remainder of the test.
  • the reference voltage changed from -0.38 on day number 2 to -0.42 on day number 293.
  • the test was discontinued on day number 293 because delamination of the cathode lamination of the cathode occurred.
  • the cathode lifetime was about 7030 hours. This again shows that when the total flow is increased in terms of stoichiometric amounts of available oxygen, the life is extended at lower potentials.
  • Example 2 An oxygen cathode test was done according to Example 1 with an operating temperature of approximately 85°C at a current density of approximately 2 amperes per square inch and a 300 grams per liter NaOH solution. Furthermore, the membrane utilized in the subject test was a standard NAFION. This experimental cell was operated using various types of cathodes. Comparative cell voltages for the different cathodes were obtained as follows:
  • Example 1 An oxygen cathode test was done according to Example 1 wherein the run was made on air which was not scrubbed of carbon dioxide. The cathode was broken in on oxygen and then switched to air, and failure occurred less than 48 hours after switching to air. This performance was typical of cathodes supplied with air which contained carbon dioxide, thus, showing the necessity of removing carbon dioxide for the lifetime of an oxygen cathode.
  • the basic conditions were as those contained in runs according to Examples 1 - 3 and the table below shows the cell voltages and reference voltage along with remarks.
  • Oxygen cathode tests were done according to Example 1 wherein the total air flow rate was varied according to Figure 2 of the drawings and with the pressure also varied. As seen in Figure 2, the cathode potential decreased with Increasing flowrates and also decreased with increasing pressures. In each case the air supplied was free of carbon dioxide and humidified.
  • the cathode tests as illustrated by the examples above were ended in each case when the reference voltage reached -1.00 or when delamination of the various layers of the cathode occurred.
  • the air (or oxygen) flow was recorded on the cathode life cell test data sheets as the height (in millimeters) of the steel ball on the Matheson number 601 flow meter (except for Example 3 for a which a Matheson number 602 flow meter was used). These readings were then converted into cubic centimeters per minute by referring to the appropriate calibration curves.
  • the examples give results of the cathode tests where the pressure differentials in the range of 100 grams per square centimeter (40 inches of water). The term pressure differential means the net pressure exerted between the two sides of the cathode.
  • the difference between the pressure and the oxidizing gas compartment (100 grams per square centimeter above atmospheric pressure) and the average hydrostatic pressure exerted by the electrolyte on the other side of the cathode (10 grams per square meter) is approximately 100 grams per square centimeter.
  • the hydrostatic pressure is calculated by multiplying the density of the electrolyte (1.33) by average height above the cathode which averaged 3 inches.
  • the useful range of pressure chterential probably is in the range of 0.25 through 500 grams per square centimeter (0.1 to 200 inches of water column). It is expected that those cathodes utilizing atmospheric pressure or where the gas compartment pressure is not allowed to exceed atmospheric pressure would be less than 1240 hours of lifetime obtained in Example 2 for instance.

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EP79300369A 1978-03-13 1979-03-09 Chloralkali Elektrolysezelle und Verfahren zu deren Betrieb Expired EP0004191B1 (de)

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US88575478A 1978-03-13 1978-03-13
US885754 1978-03-13

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EP0004191A3 EP0004191A3 (en) 1979-10-31
EP0004191B1 EP0004191B1 (de) 1982-05-05

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AU (1) AU529294B2 (de)
BR (1) BR7901504A (de)
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Cited By (2)

* Cited by examiner, † Cited by third party
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GB2168079A (en) * 1984-12-10 1986-06-11 United Technologies Corp Use of gas depolarized anodes for the electrochemical production of adiponitrile
US6627662B2 (en) 1995-10-10 2003-09-30 William John Louis, Austin And Repatriation Medical Centre 3-amino-propoxyphenyl derivatives (I)

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DE3420483A1 (de) * 1984-06-01 1985-12-05 Hoechst Ag, 6230 Frankfurt Bipolarer elektrolyseapparat mit gasdiffusionskathode
PL409557A1 (pl) 2014-09-22 2016-03-29 Ori-Med Spółka Z Ograniczoną Odpowiedzialnością Krzesło ortopedyczne zwłaszcza do rehabilitacji skolioz
DE102015014515A1 (de) 2015-11-11 2017-05-11 Dräger Safety AG & Co. KGaA Elektrolytleiter, Verfahren zur Herstellung eines Elektrolytleiters sowie ein elektrochemischer Gassensor und ein Gasmessgerät mit einem solchen

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Cited By (3)

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Publication number Priority date Publication date Assignee Title
GB2168079A (en) * 1984-12-10 1986-06-11 United Technologies Corp Use of gas depolarized anodes for the electrochemical production of adiponitrile
US6627662B2 (en) 1995-10-10 2003-09-30 William John Louis, Austin And Repatriation Medical Centre 3-amino-propoxyphenyl derivatives (I)
US7129379B2 (en) 1995-10-10 2006-10-31 William John Louis, Austin And Repatriation Medical Centre 3-amino-propoxphenyl derivatives (l)

Also Published As

Publication number Publication date
IL56855A (en) 1982-07-30
BR7901504A (pt) 1979-10-09
CA1155792A (en) 1983-10-25
NO153224C (no) 1986-02-05
PL214074A1 (de) 1980-03-24
SU860711A1 (ru) 1981-08-30
DE2962670D1 (en) 1982-06-24
PL116783B2 (en) 1981-06-30
AU529294B2 (en) 1983-06-02
IN152982B (de) 1984-05-19
ZA791153B (en) 1980-03-26
EP0004191B1 (de) 1982-05-05
MX154417A (es) 1987-08-14
YU58579A (en) 1983-01-21
JPS54132498A (en) 1979-10-15
NO790819L (no) 1979-09-14
AU4504779A (en) 1979-09-20
EP0004191A3 (en) 1979-10-31
IL56855A0 (en) 1979-05-31
DD142456A5 (de) 1980-06-25
ES478598A1 (es) 1980-06-16
NO153224B (no) 1985-10-28

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