WO2000050339A1 - Procede de production de polysulfure par oxydation electrolytique - Google Patents

Procede de production de polysulfure par oxydation electrolytique Download PDF

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Publication number
WO2000050339A1
WO2000050339A1 PCT/JP2000/001146 JP0001146W WO0050339A1 WO 2000050339 A1 WO2000050339 A1 WO 2000050339A1 JP 0001146 W JP0001146 W JP 0001146W WO 0050339 A1 WO0050339 A1 WO 0050339A1
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WO
WIPO (PCT)
Prior art keywords
anode
polysulfide
chamber
producing
anode chamber
Prior art date
Application number
PCT/JP2000/001146
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English (en)
Japanese (ja)
Inventor
Tetsuji Shimohira
Tatsuya Andoh
Junji Tanaka
Keigo Watanabe
Yasunori Nanri
Original Assignee
Kawasaki Kasei Chemicals Ltd.
Nippon Paper Industries Co., Ltd.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Kawasaki Kasei Chemicals Ltd., Nippon Paper Industries Co., Ltd. filed Critical Kawasaki Kasei Chemicals Ltd.
Priority to AU26948/00A priority Critical patent/AU2694800A/en
Publication of WO2000050339A1 publication Critical patent/WO2000050339A1/fr

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Classifications

    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
    • D21C11/00—Regeneration of pulp liquors or effluent waste waters
    • D21C11/0057—Oxidation of liquors, e.g. in order to reduce the losses of sulfur compounds, followed by evaporation or combustion if the liquor in question is a black liquor

Definitions

  • the present invention relates to a method for producing a polysulfide by electrolytic oxidation, and more particularly to a method for producing a polysulfide digestion liquid by electrolytically oxidizing a white liquor or a green liquor in a valve production process.
  • the cooking liquor in the polysulfide cooking process is manufactured by oxidizing an alkaline aqueous solution containing sodium sulfide, a so-called white liquor, with molecular oxygen such as air in the presence of a catalyst such as activated carbon (for example, the following reaction formula 1).
  • a catalyst such as activated carbon (for example, the following reaction formula 1).
  • polysulfide is also referred to as borosulfide sulfur (PS—S).
  • PS—S borosulfide sulfur
  • sodium polysulfide Na 2 SX has zero valence, ie, atom ( X-1 1) means the number of pieces.
  • N which is equivalent to the number of oxidations in polysulfide ions—2 (SX 2 -one atom equivalent to one atom) and sulfide ions (S 2 ⁇ ), is collectively referred to as N in this specification.
  • SX 2 -one atom equivalent to one atom sulfide ions
  • S 2 ⁇ sulfide ions
  • PCT International Publication WO95 / 0701 describes a method for electrolytically producing a polysulfide cooking liquor.
  • an anode is used in which a carrier is coated with an oxide of ruthenium, iridium, platinum, or palladium.
  • a three-dimensional mesh electrode of a carrier in which a number of expanded metals are combined is disclosed.
  • Jing International Publication, No. 0977/41192 describes a process for the electrolytic production of polysulfide cooking liquors by the present applicants.
  • a porous anode made of at least carbon is used as the anode, and in particular, an aggregate of carbon fibers having a diameter of 1 to 300 m is used.
  • the present invention provides a process for producing a cooking liquor containing a high concentration of polysulfide by electrolysis from a solution containing sulfide ions, in particular, a white liquor or a green liquor in a pulp production process, by reducing the by-product of thiosulfate to a high level. It is intended to manufacture at a selectivity and low power. Disclosure of the invention
  • the present invention introduces a solution containing a sulfide ion into an anode chamber of an electrolytic cell having an anode chamber in which a porous anode is provided, a force sword chamber in which a force sword is provided, and a diaphragm separating the anode chamber and the cathode chamber.
  • a method for producing a polysulfide to obtain polysulfide ions by electrolytic oxidation carrying out the third invention to provide a method for producing polysulfides which the pressure in the cathode chamber and feature is higher than the pressure in the anode chamber Best form to do
  • porous anode Various shapes and materials can be used as the porous anode in the present invention. More specifically, for example, carbon fiber, carbon fiber, carbon paper, metal foam, reticulated metal, etc. Carbon. A metal electrode having a surface modified with platinum or the like can also be used.
  • the porous anode used in the present invention preferably has a physically continuous three-dimensional network structure.
  • the surface area of the anode can be increased, and a desired electrolytic reaction occurs on the entire surface of the electrode, thereby suppressing generation of by-products.
  • the anode is made into a physical continuum rather than an aggregate of fibers, the anode As a result, the cell voltage can be further reduced because it exhibits sufficient electrical conductivity and the IR drop at the anode can be reduced.
  • the network structure is a physically continuous structure, and may be continuously connected by welding or the like.
  • a physically continuous three-dimensional fine structure made of nickel or a nickel alloy containing at least 50% by weight of nickel is preferred.
  • porous nickel obtained by plating nickel on the skeleton of a foamed polymer material and then baking off the polymer material inside can be given.
  • the anode having a three-dimensional network structure preferably has a diameter of 0.01 to 2 mm at a portion corresponding to a yarn of a network constituting the network. If the diameter is less than 0.01 mm, manufacturing is extremely difficult, costly, and handling is not easy. When the diameter exceeds 2 mm, a large surface area of the anode cannot be obtained, the current density on the anode surface increases, and not only is it easy to generate by-products such as thiosulfate ions, but also the anode is made of metal. In this case, anodic dissolution is likely to occur, which is not preferable. It is particularly preferred if the diameter is between 0.02 and 1 mm.
  • the average pore size of the anode network is preferably 0.001 to 5 mm. If the average pore size of the mesh is larger than 5 mm, the anode surface area cannot be increased, the current density on the anode surface increases, and not only is it easy to generate by-products such as thiosulfate, but also as an anode If a metal is used, anodic dissolution is likely to occur. If the average pore size of the mesh is smaller than 0.001 mm, clogging occurs when solid components are mixed in the electrolytic cell, and problems in the electrolytic operation when the pressure loss of the solution increases become large. It is not preferable because it may occur.
  • the average pore size of the anode mesh is 0.
  • the pressure force Sword chamber is carried out in large conditions also Ri by the pressure in the anode chamber .
  • An electrolytic cell generally has a structure in which a diaphragm is sandwiched between an anode and a cathode. From the viewpoint of assembly accuracy and protection of the diaphragm, the anode and the cathode are arranged at a relatively large distance. Specifically, a distance of about several mm is often provided. The diaphragm placed between them will approach the anode side or approach the force side depending on the electrolysis conditions. In the present invention, the diaphragm is Improve current efficiency, etc.
  • the electrolysis operation is performed under the condition that the pressure in the force source chamber is higher than the pressure in the anode chamber. By doing so, the diaphragm is pressed against the anode, so that the anolyte can sufficiently flow inside the porous anode, and a high selectivity is realized.
  • a solution for increasing the pressure in the cathode chamber higher than the pressure in the anode chamber
  • a solution for introducing a flow rate of a solution (hereinafter, referred to as “force sword solution”) to the sword chamber into the anode chamber is used.
  • force sword solution a solution for introducing a flow rate of a solution
  • At least the surface of the porous anode is made of nickel or a nickel alloy containing nickel in an amount of 50% by weight or more. Since at least the surface portion of the anode is made of nickel, the anode has practically sufficient durability in the production of polysulfide.
  • Nickel is a suitable material in the present invention because nickel is inexpensive and its elution potential including its oxide is higher than the potential for generating polydisulfide sulfate.
  • the porous anode in the present invention the surface area per effective current area of the diaphragm which separates the anode chamber and the cathode-de chamber 2 ⁇ 1 0 O m 2 Zm 2 2 m 2 is preferred anode surface area in the range of Zm 2 If the anode is a metal, the current density on the anode surface increases, and not only is it easy to generate by-products such as thiosulfate ions, but also the anode is liable to dissolve when the anode is a metal.
  • the anode surface area is larger than 10 O m 2 / m 2, the pressure loss of the porous anode itself becomes high, and it is difficult to make the pressure in the force source chamber higher than the pressure in the anode chamber. It is not preferable because it may be caused. More preferably, the anode surface area is 5 to 50 m 2 m 2 per effective conducting area of the membrane.
  • the anode surface area per anode chamber volume is 500 to 2000 m2 / m3 . If the surface area of the anode is smaller than 50 Om3, the current density at the anode surface increases, and by-products such as thiosulfate are formed. In addition to this, it is not preferable that the anode is made of a metal because the anode is likely to dissolve. If the surface area of the anode is more than 2000 m 2 / m 3, it is not preferable because a problem in electrolysis operation may occur when the pressure loss of the liquid increases.
  • the anode surface area of the anode chamber per volume 1 0 0 0 ⁇ 2 0 0 0 0 m and even more preferably in the range of 2 / m 3.
  • the current density at the diaphragm surface is 2 ⁇ 1 5 k A / m 2 is still more preferably les, the c present invention, the area of the diaphragm, in Anodo surface because of the use of large anodes surface area It can be operated in a range where the current density is small.
  • each portion is assumed to be uniform that, if the anode of the surface area was determined current density at the anode surface, the value is 5 ⁇ 3 0 0 0 A / m 2 Is preferred. A more preferred range is from 10 to 150 A / m 2. If the current density on the anode surface is less than 5 A / m 2, unnecessarily large electrolytic equipment will be required, which is not desirable. When the current density at the anode surface exceeds 300 A / m2, not only the by-products such as thiosulfuric acid, sulfuric acid, and oxygen are increased, but also when the anode is a metal, anodic dissolution may occur. Is not preferred.
  • the average superficial velocity of the anolyte is preferably 1 to 30 cmZ seconds. If the time is longer than 30 c seconds, an unnecessarily large electrolytic facility is required, which is not preferable. If the average superficial velocity of the anolyte is too low, not only is by-products such as thiosulfuric acid, sulfuric acid, and oxygen increased, but if the anode is a metal, the anode may be dissolved, which is not preferable. It is more preferable that the average superficial velocity of the anolyte is 1 to 15 cs, particularly 2 to 10 cMz. Although the flow rate of the force solution is not limited, it is determined by the magnitude of the buoyancy of the generated gas, the allowable pressure of the electrolytic cell, the concentration of alkali generated on the cathode side, and the like.
  • the anode itself preferably has sufficient voids, and the porosity of the porous anode is preferably 30 to 99%. If the porosity is less than 30%, the pressure loss may increase, which is not preferable. If the porosity is more than 99%, it is difficult to increase the anode surface area. It is particularly preferable that the porosity is 50 to 98%.
  • a current is supplied to the anode through the anode current collector.
  • a material of the current collector a material having excellent alkali resistance is preferable. For example, nickel, titanium, carbon, gold, platinum, stainless steel, and the like can be used.
  • the current collector is attached to the back surface or the periphery of the anode. If the current collector is mounted on the back of the anode, its surface may be planar.
  • the electric current may be supplied simply by mechanical contact with the anode, but it is preferable that the electric current is physically bonded by welding or the like.
  • the force sword material an alkali-resistant material is preferable, and nickel, Raney nickel, nickel sulfide, steel, stainless steel and the like can be used.
  • the force sword is used in the form of a flat plate or mesh, one or more of which are in a multilayer structure.
  • a three-dimensional electrode combining linear electrodes can also be used.
  • electrolyzer a two-chamber electrolyzer comprising one anode chamber and one power sword chamber is used. Electrolyzers combining three or more rooms are also used. Multiple cells can be arranged in a monopolar or bipolar configuration.
  • a cation exchange membrane as a diaphragm, that is, a membrane that separates and separates the anode chamber and the power source chamber.
  • the cation exchange membrane directs cations from the anode compartment to the force sword compartment, preventing the transfer of sulfide and polysulfide ions.
  • a polymer membrane in which a cation exchange group such as a sulfonic acid group or a carboxylic acid group is introduced into a hydrocarbon-based or fluororesin-based polymer is preferable. If there is no problem in terms of alkali resistance, a bipolar membrane or an anion exchange membrane can be used.
  • the temperature of the anode compartment is preferably between 70 and 110 ° C. If the temperature of the anode chamber is lower than 70 ° C, not only is the cell voltage increased, but also sulfur deposition and by-products are easily generated. If the anode is a metal, the anode may be dissolved, which is preferable. Nare, The upper temperature limit is practically limited by the material of the cell or diaphragm.
  • the anode potential, S 2 2-a oxidation product of sulfide ions, S 3 2-, S 4 2 -, S 5 2 - polysulfide ions such as (SX 2 -) is generated, the Chio sulfate ions It is preferable to maintain it so as not to produce by-products.
  • the operation is preferably performed so that the anode potential is in the range of 0.75 to 0.25 V. If the anode potential is lower than 0.75 V, the formation of polysulfide ions does not substantially occur, which is not preferable. If the anode potential is higher than +0.25 V, not only is by-products such as thiosulfate ions formed, but also if the anode is a metal, it may cause anode dissolution, which is not preferable.
  • the electrode potential represents a potential measured with respect to a Hg / Hg 2 C 12 reference electrode in a 25 ° C. saturated KC 1 solution.
  • the anode is a three-dimensional electrode, it is not easy to measure the anode potential accurately. Therefore, industrially, it is preferable to control the manufacturing conditions by controlling the cell voltage and the current density on the diaphragm surface, rather than controlling the manufacturing conditions by controlling the potential.
  • the electrolysis method is preferably a constant current electrolysis, but the current density can be changed.
  • the solution containing sulfide ions supplied to the anode compartment can be at least partially circulated to the same anode compartment after being electrolytically oxidized in the anode compartment.
  • a process for supplying to the next step without performing such a circulation that is, a so-called one-pass process can also be adopted.
  • the solution containing sulfide ions is white liquor or green liquor in the manufacturing process of the valve, the electrolytically oxidized white liquor or green liquor flowing out of the anode compartment is not circulated to the same anode compartment. It is preferable to supply to the next step.
  • an alkali metal ion is preferable.
  • sodium or power beam is preferred.
  • the method of the present invention is particularly suitable for a method of treating a white liquor or a green liquor in a pulp 'production process to obtain a polysulfide cooking liquor.
  • the term “white liquor” or “green liquor” includes liquids that have been subjected to concentration, dilution, or separation of solids, respectively, for the white liquor or green liquor.
  • the composition of white liquor is, for example, that of white liquor used in current kraft pulp digestion, usually contains 2 to 6 mol 1 ZL as alkali metal ions, of which 90% or more is sodium ion. Yes, the rest is almost force-ion.
  • Anions are mainly composed of hydroxide ion, sulfide ion and carbonate ion, and also include sulfate ion, thiosulfate ion, chloride ion and sulfite ion. It also contains trace components such as potassium, silicon, aluminum, phosphorus, magnesium, copper, manganese, and iron.
  • the composition of the green liquor is that sodium sulfide and sodium hydroxide are the main components of the white liquor, whereas sodium sulfide and sodium carbonate are the main components.
  • Other anions and trace components in the green liquor are the same as in the white liquor.
  • the strength depends on the sulfide ion concentration in the white liquor or green liquor.
  • the PS-S concentration in the solution obtained by electrolysis is 5 to 15 g / L is preferred. If it is less than 5 gZL, the effect of increasing the pulp yield during cooking may not be sufficiently obtained.
  • the concentration of PS—S is higher than 15 g / L, the amount of Na 2 S decreases, so that the pulp yield does not increase and thiosulfate ions are easily produced during electrolysis.
  • the average value of X of the existing polysulfide ions (SX 2- ) exceeds 4, thiosulfate ions are similarly produced as a by-product during electrolysis.
  • the average value of X of the polysulfide ions in the cooking liquor is 4 or less, particularly 3.5 or less, because dissolution is likely to occur.
  • the conversion (reaction rate) of sulfide ions to PS—S is preferably 15% or more and 75% or less, more preferably 72% or less.
  • various reactions can be selected for the reaction in the power source chamber, it is preferable to use a reaction in which hydrogen gas is generated from water. Alkali hydroxide is generated from the resulting hydroxide ions and alkali metal ions that have migrated from the anode compartment.
  • the solution introduced into the cathode chamber is preferably a solution substantially consisting of water and an alkali metal hydroxide, particularly preferably a solution consisting of water and a hydroxide of sodium or magnesium.
  • concentration of the alkali metal hydroxide is not limited, for example, l to 15 mol Z L, preferably 2-5mo 1ZL.
  • a solution having an ionic strength lower than the ionic strength of the white liquor flowing through the anode chamber is used as the catholyte, it is possible to prevent insoluble components from depositing on the diaphragm.
  • a two-chamber electrolytic cell was assembled as follows.
  • a nickel foam (available from Sumitomo Electric Industries, trade name Celmet, height 10 OmmX width 2 OmmX thickness 4 mm) was electro-welded to the nickel current collector plate.
  • a fluororesin-based cation exchange membrane (Flemion, manufactured by Asahi Glass Co., Ltd.) was prepared as a force sword using mesh Raney nickel as a diaphragm.
  • the anode chamber is fitted with a 5 mm thick anode chamber frame, and a diaphragm, a force sword, a 4 mm thick cathode chamber frame, and a cathode chamber plate are stacked on top of each other and pressed down and fixed.
  • the anode chamber has a height of 100 mm and a width of 100 mm. 2 Omm, and a thickness of 5 mm, the shape of the cathode-de chamber height 10 Omm, a width 20 mm, thickness 5 mm, the effective area of the diaphragm is 2 O cm 2.
  • both the anolyte and the power source fluid flowed from the bottom to the top in the height direction of each chamber so that the pressure in the power source chamber was higher than that in the anode chamber.
  • Anode chamber thickness 4 mm
  • Anode thickness 4 mm
  • Porosity in the anode chamber 95% Average liquid superficial velocity in the node chamber: 4 cmZ seconds
  • Node surface area per anode chamber volume 7000 m 2 / m 3
  • Average pore size of the mesh 0.5 1 mm Surface area per diaphragm area: 28 m 2 / m 2 Electrolysis temperature: 85 ° C Current density at the diaphragm: 6 kA / m 2
  • model white liquor (N a 2 S: Iou terms of atom in 1 6 g / L, N a OH: 90 gZL, N a 2 CO 3: 34 g / L) was 1 L preparation, ⁇ Roh one It was circulated at a flow rate of 192 mLZ (average superficial velocity in the anode chamber: 4 cs) while introducing from the lower side of the anode chamber and extracting from the upper side.
  • 2 L of 3 N Na ⁇ H aqueous solution as the power source liquid
  • Circulation was performed at a flow rate of 80 mL / min (superficial velocity: 1.3 cmZ seconds).
  • Heat exchangers were provided on both the anode and cathode sides, and the anolyte and catholyte were heated and introduced into the cell.
  • a constant current electrolysis is performed at a current of 12 A (current density at the diaphragm: 6 kA / m 2 ) to synthesize a polysulfide digest, measure the cell voltage at a predetermined time, and sample the circulating fluid. Then, PS-S, sulfide ion and thiosulfate ion in the solution were analyzed and quantified. The analysis was performed based on the method described in Japanese Patent Application Laid-Open No. 7-92148.
  • the cell voltage was constant at about 1.1 V for about one hour from the start of electrolysis, but then gradually increased.
  • the thiosulfate ion concentration was 1.3 V at 1 hour and 40 minutes after the concentration began to increase, and after another 20 minutes, the voltage increased to about 2 V, and the nickel leaching reaction began to proceed.
  • “Current efficiency” and “selectivity” are defined as follows when the generated PS-S concentration is A (gZL) and the generated thiosulfate ion concentration is B (gZL) in terms of zeolite atoms. . Until the nickel elution reaction takes place during the electrolysis operation, only PS-S and thiosulfate ions are generated, so they may be defined as follows.
  • Example 2 The same electrolytic cell as in Example 1 was used, but in contrast to Example 1, constant-current electrolysis was performed under conditions where the pressure in the anode chamber was higher than the pressure in the force-side chamber. This maintained a 1 mm gap between the anode and the diaphragm, increasing the thickness of the anode compartment to 5 mm and reducing the thickness of the force sword compartment to 4 mm. Average empty space of liquid in cathode chamber and cathode chamber In order to set the speed to the same value as in Example 1, the flow rate of the anolyte was changed to 24 OmLZ and the flow rate of the catholyte was changed to 64 mLZ. The time courses of the quantitative values of the concentrations of various sulfur compounds and the measured values of the cell voltage were as follows.
  • the composition of the polysulfide cooking liquor was as follows: PS-S was 10. O g / L, Na 2 S was 5.4 gZL in terms of zeo atoms, and the increased thiosulfate ion was zeolite. It was 0.64 g / L in terms of atoms, and the average value of X of the polysulfide ion (S x 2-) was 2.9. During this period, the current efficiency of PS-S was 89% and the selectivity was 94%.
  • the cell voltage from the start of electrolysis to about one hour was constant at about 1.3 V.
  • the by-product of a thiosulfate ion is extremely small, a high concentration polysulfide is contained, and the cooking liquor which has a lot of residual Na2S state can be maintained at a low power while maintaining a high selectivity. Can be manufactured.
  • the use of the polysulfide cooking liquor thus obtained from the white liquor or green liquor in the halve production process for the cooking can effectively increase the yield of rubbish and rub.

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Abstract

L'invention concerne un procédé de production de polysulfures, consistant à introduire une solution contenant des ions sulfure dans un compartiment à anode d'une cuve à électrolyse qui comprend un compartiment à anode présentant une anode poreuse, un compartiment à cathode présentant une cathode, et une membrane séparant le compartiment à anode et le compartiment à cathode, et effectuant l'oxydation électrolytique, pour produire ainsi des ions polysulfure. Ce procédé est caractérisé en ce que la pression dans le compartiment à cathode est supérieure à celle qui règne dans le compartiment à anode. Ce procédé peut être mis en oeuvre pour produire une solution de digestion présentant une teneur élevée en polysulfure-soufre, avec un sélectivité élevée et une faible consommation électrique, la présence d'ion thiosulfate comme sous-produit étant nettement réduite.
PCT/JP2000/001146 1999-02-26 2000-02-28 Procede de production de polysulfure par oxydation electrolytique WO2000050339A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU26948/00A AU2694800A (en) 1999-02-26 2000-02-28 Method for producing polysulfide by electrolytic oxidation

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP11051016A JP2000247611A (ja) 1999-02-26 1999-02-26 電解酸化による多硫化物の製造方法
JP11/51016 1999-02-26

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WO2000050339A1 true WO2000050339A1 (fr) 2000-08-31

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WO (1) WO2000050339A1 (fr)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2001073180A (ja) * 1999-09-06 2001-03-21 Kawasaki Kasei Chem Ltd 多硫化物の製造方法

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5624545A (en) * 1993-06-28 1997-04-29 Eka Nobel Inc. Production of polysulphide by electrolysis of white liquor containing sulphide
US5653861A (en) * 1995-04-06 1997-08-05 Eka Nobel Ab Electrochemical process
WO1997041295A1 (fr) * 1996-04-26 1997-11-06 Asahi Glass Company Ltd. Procede de production de polysulfures par oxydation electrolytique

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5624545A (en) * 1993-06-28 1997-04-29 Eka Nobel Inc. Production of polysulphide by electrolysis of white liquor containing sulphide
US5653861A (en) * 1995-04-06 1997-08-05 Eka Nobel Ab Electrochemical process
WO1997041295A1 (fr) * 1996-04-26 1997-11-06 Asahi Glass Company Ltd. Procede de production de polysulfures par oxydation electrolytique

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AU2694800A (en) 2000-09-14

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