CN105074056A - Techniques for production of chlorated products and prefabricated cathode structures - Google Patents

Techniques for production of chlorated products and prefabricated cathode structures Download PDF

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CN105074056A
CN105074056A CN201380073663.XA CN201380073663A CN105074056A CN 105074056 A CN105074056 A CN 105074056A CN 201380073663 A CN201380073663 A CN 201380073663A CN 105074056 A CN105074056 A CN 105074056A
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ionogen
negative electrode
phosphate
electrochemical process
protectiveness
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R.舒尔茨
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Hydro Quebec
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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
    • C25B11/00—Electrodes; Manufacture thereof not otherwise provided for
    • C25B11/04—Electrodes; Manufacture thereof not otherwise provided for characterised by the material
    • C25B11/051—Electrodes formed of electrocatalysts on a substrate or carrier
    • C25B11/073—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the electrocatalyst material
    • C25B11/075—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the electrocatalyst material consisting of a single catalytic element or catalytic compound
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D9/00—Electrolytic coating other than with metals
    • C25D9/04—Electrolytic coating other than with metals with inorganic materials
    • C25D9/08—Electrolytic coating other than with metals with inorganic materials by cathodic processes
    • C25D9/10—Electrolytic coating other than with metals with inorganic materials by cathodic processes on iron or steel
    • 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
    • C25B1/24—Halogens or compounds thereof
    • C25B1/26—Chlorine; Compounds thereof
    • C25B1/265—Chlorates
    • 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
    • C25B11/00—Electrodes; Manufacture thereof not otherwise provided for
    • C25B11/04—Electrodes; Manufacture thereof not otherwise provided for characterised by the material
    • C25B11/051—Electrodes formed of electrocatalysts on a substrate or carrier
    • 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
    • C25B11/00—Electrodes; Manufacture thereof not otherwise provided for
    • C25B11/04—Electrodes; Manufacture thereof not otherwise provided for characterised by the material
    • C25B11/051—Electrodes formed of electrocatalysts on a substrate or carrier
    • C25B11/055—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the substrate or carrier material
    • C25B11/057—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the substrate or carrier material consisting of a single element or compound
    • C25B11/061—Metal or alloy
    • 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
    • C25B15/00—Operating or servicing cells
    • C25B15/02—Process control or regulation
    • 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
    • C25B9/00—Cells or assemblies of cells; Constructional parts of cells; Assemblies of constructional parts, e.g. electrode-diaphragm assemblies; Process-related cell features
    • C25B9/17—Cells comprising dimensionally-stable non-movable electrodes; Assemblies of constructional parts thereof

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Automation & Control Theory (AREA)
  • Electrolytic Production Of Non-Metals, Compounds, Apparatuses Therefor (AREA)

Abstract

Techniques for producing chlorinated products include an electrochemical process that includes the steps of providing an anode and a cathode in an electrolyte comprising impurities such as calcium ions, applying a voltage between the anode and the cathode under conditions to form an electrolysis product such as sodium chlorate in the electrolyte, and providing sufficient phosphate ions to form with at least a portion of the calcium ions a protective external layer including a calcium phosphate compound such as hydroxyapatite on the cathode, while preferably avoiding other phosphate precipitations. A pre-determined amount of phosphate ions may be added, for example, based on the surface area of the cathode in order to form the protective layer. Related uses and systems are also described. Prefabricated cathodes may include a substrate, a catalytic intermediate layer and a calcium phosphate protective layer.

Description

For the manufacture of technology and the prefabricated cathode structure of chlorizate
Technical field
Present invention relates in general to the field manufacturing chlorizate, and the cathode protection technology related more specifically in the manufacture of sodium chlorate and prefabricated cathode structure.
Background technology
Sodium chlorate (NaClO 3) commercially by the electrochemical process manufacture according to following total reaction:
NaCl+3H 2O＝>NaClO 3+3H 2(1)
There is hydrogen as follows at cathode side and release (H 2):
2H 2O+2e -＝>2OH -+H 2(2)
And form chlorate anions (ClO in anode side by series reaction 3 -):
2Cl -＝>Cl 2+2e -
Cl 2+H 2O＝>HClO+Cl -+H +
HClO＝>ClO -+H +
2HClO+ClO -＝>ClO 3 -+2Cl -+2H +(3)
At cathode side, hydrogen current efficiency (CE) is defined as hydrogen flow rate (J h2) and the total current being applied to electrochemical cell (pond, cell) between ratio:
CE＝J H2/(I/2F)(4)
Wherein I is the electric current applied, and F is Faraday's number.
For negative electrode, usually use the mild steel with low carbon content, and use the anode (DSA) of dimensional stabilizing as anode.In fact, electrochemical reaction often occurs in the undivided cell (undividedcell) using one pole or bi-polar configuration.In bi-polar configuration, anode portion and negative pole part are in physics and electrical contact and result, when galvanic protection no longer its institute (inplace) time can there is serious galvanic corrosion problem closing down period.
Typical electrolyte solution comprises the NaClO of about 550g/l 3, 110g/l the NaClO of NaCl and 1-3g/l.Technique is typically at the pH of about 6.5, the temperature of 60 DEG C-85 DEG C and 2-4kA/m 2current density under occur.
Some side reactions can cause the CE reduced, such as, in the reduction of cathode side hypochlorite and chlorate anions:
ClO -+H 2O+2e -＝>Cl -+2OH -(5)
ClO 3 -+3H 2O+6e -＝>Cl -+6OH -(6)
Can be the reduction that important (especially between the starting period) another parasitic reaction is ferriferous oxide on steel negative electrode, this causes from the explosive releasing oxygen of electrolyzer:
MO+2e -=>M+O 2-(negative electrode) (7)
O 2-=>1/2O+2e -(anode)
Oxygen also can be produced by the anodic oxidation of hypochlorite according to following:
OCl -+H 2O＝>O 2+2H++Cl -+2e -(8)
And it also can being decomposed to form by hypochlorite as follows:
2OCl -＝>2Cl -+O 2(9)
2HClO＝>O 2+2HCl(10)
In ionogen, the existence of Ni, Co or Cu ionic impurity can accelerate the decomposition of hypochlorite.Under 1ppm level content, Ni, Co and Cu can cause at 70 DEG C and 3kA/m 2o under current density in cell gas 2increase by 2.0%, 1.0% and 0.7% respectively.Therefore, among the various elements of part that can be electrochemical cell or electrode, usually Ni is avoided especially.
In order to reduce aforementioned negative electrode parasitic reaction and improve hydrogen CE, industry adds dichromate (Na with the concentration of 3-8g/l to ionogen usually 2cr 2o 7).During cathodic polarization, chromium (VI) is reduced to chromium (III) and the film of chromium hydroxide (III) is formed on cathode surface.This porous-film contributes to protection negative electrode from corrosion, hinders negatively charged ion to the migration of electrode surface and suppresses undesirable side reaction, still allows evolving hydrogen reaction to occur simultaneously.
Cr 2O 7 -2+8H ++6e -＝>2Cr(OH) 3+H 2O(11)
Chromic salt also serves as pH buffer reagent and it makes the generation of oxygen gas by-products reduce.Due to chromic toxicity (this makes art breading cost increase), wish the replacer or the substitute that find this practice.Therefore, expect to find so avirulent coating material: it, once be deposited on the surface of negative electrode, will suppress the reduction of hypochlorite and chlorate anions and improve CE.
Described ionogen is high corrosiveness and iron cathode is easily corroded in this environment when there is not galvanic protection.Corrosion make the lost of life of negative electrode and make described ionogen pollute by iron contamination.Depend on operational condition and close down frequency, cathode life shortly can reach 5 years.Due to this reason, the negative electrode that some industrial applications are thicker and with interval operation between larger electrode to avoid the short circuit caused by corrosion product.In addition, have been found that the reduction of ferriferous oxide catalysis chlorate anions and reduce CE.But, iron cathode is cheap, and they have relatively low cathode overpotential and their surface is updated along with the removing of corrosion layer during each generation long power failure.Therefore, after the event of closing down, bath voltage is normally lower, but CE is still effective, until chromium hydroxide film is formed from the teeth outwards again.
Another challenge in sodium chlorate manufacture field is the corrosion on negative electrode, particularly when using iron cathode.
In order to make the corrosive nature on negative electrode minimize, can consider to use stainless steel cathode to replace iron, but stainless steel has much higher cathode overpotential due to the chromium in this alloy usually.The overpotential of pure chromium is than the overpotential height at least 100mV of pure iron.In addition, the austenitic stainless steel of 300 series is also containing Ni, and it can affect the generation of oxygen gas by-products as previously mentioned.When there is not dichromate, the speed of chlorate anions reduction and CE depend on essence and the character of electrode materials strongly.For 20 to three ten years of the past, for finding the research of the sub of iron cathode carrying out always, but still in use iron cathode.Therefore, so new cathode material is expected: it is electroactive, highly corrosion resistant and almost inertia (noble) the same as DSA negative electrode minimizes to make the galvanic corrosion in bi-polar configuration.
Another challenge in sodium chlorate manufacture field relates to ionogen impurity.During electrolysis, when the plating of ionogen impurity or when to be deposited on electrode and to hoodwink or poison electro catalytic activity, observe the rising gradually of bath voltage.Under the effect of electric field, the impurity such as Ca of positively charged 2+and Mg 2+attracted by towards negative electrode, and negative charge impurity such as sulfate ion moves towards anode.B.V.Tilak etc. are published in the ElectrochemicalSocietyProceedings of 1999, the paper being entitled as " Electrolyticsodiumchloratetechnology:currentstatus " in vol.99-21 is mentioned, the settling that negative electrode finds usually is the oxyhydroxide of calcium and magnesium.B.V.Tilak etc. show, the Ca under 1ppm level + 2impurity can cause the voltage of monthly about 50-75mV to raise, and the voltage of monthly about 100mV can be caused under 1.5ppm level to raise.Under 20ppb level, in operation in 2 years, voltage raises as only 50mV.Because most of manufactory operates under ppm calcium level, therefore their usually the annual acid elution that uses carry out their electrolyzer clean for several times to remove these hoodwinking property settlings.
Recently, the novel cathode presenting the about overpotential of 200mV lower than the overpotential of iron has been reported.The Canadian Patent No.2687129 of Schulz etc. and Canadian patent application No.2778865 describes type Fe 3al (Ru) and Fe 3the new cathode material of AlTa (Ru), it is used in when improving relative to iron and manufactures sodium chlorate.These materials have the catalytic species (Ru) in iron aluminide metallic matrix.Although they are for the efficiency of evolving hydrogen reaction, unfortunately, these new cathode materials also affect by calcium impurities.In some cases, the calcium impurities higher than ppm mark can have negative impact to electrode performance.
When the chlor-alkali using highly porous film or barrier film anolyte and catholyte compartment to be separated wherein, calcium impurities also can have negative impact.The calcium impurities being in ppm level can quite easily block these films and due to this reason, develop method calcium impurities being reduced to ppb level.The U.S. Patent No. 4,176 of Darlington, 022 described such method in 1979.After removing particulate, usually by starting as follows: the process of salt solution SODA ASH LIGHT 99.2 is precipitated as calcium carbonate to make most of calcium, by filtration or other physical separation method, calcium carbonate is separated from ionogen.This makes calcium reach 2-3ppm level usually.Afterwards, ionogen can be made to comprise to obtain the salt solution being less than about 0.5ppm (500ppb) calcium by ion exchange column.Finally, U.S. Patent No. 4,176,022 propose to alkalescence salt solution add phosphate radical with formed believed as be substantially insoluble to salt solution apatite calcium calcium phosphate compound and afterwards described compound is separated from ionogen.Between the Formation period of described compound, keep the pH of this salt solution higher than 10 and keep temperature higher than 40 DEG C to reduce its solubleness in this salt solution further.They also propose to add seed such as calcium phosphate (Ca to ionogen 3(PO 4) 2) or calcium hydroxide to make precipitin reaction easy.Final calcium impurities level is about 20/1000000000ths parts.Typically, the concentration of the phosphate radical of this salt solution is added into for about 0.1-about 1 % by weight.As an example, they add 0.44g and the 2.24g phosphoric acid (H of 85% respectively to one liter of salt solution 3pO 4) so that calcium is reduced to 200ppb and 20ppb level.Recently, in 2008, Canadian patent application No.2655726 proposes similar approach to be come from salt solution removing calcium.This application teach the Na of 2g 2hPO 4be added into 60ml ionogen to be reduced to calcium impurities level lower than ppm level.Such reference discloses the phosphate radical of the relatively high amount of interpolation, and object makes calcium ion be precipitated out to obtain the final calcium impurities level of target from bulk solution.
In U.S. Patent No. 4,004, in 988, Mollard etc. propose and make with the following method: for the manufacture of in the undivided cell of sodium chlorate, add an alkali metal salt of phosphoric acid or these acid for complexing calcium to ionogen.Mollard etc. disclose, and most of calcium removes with the sedimentary form that can easily filter by complexing agent during electrolytic process.In an embodiment, Mollard etc. add 0.5-2g tripoly phosphate sodium STPP (Na to the salt solution that 1kg comprises 60ppm-100ppm calcium 5p 3o 10), this is equivalent to about 0.7g-2.6g/ liter.By after electrolyzer, solution is filtered and finds that it comprises 5ppm-10ppm calcium.As in previously described reference, the concentration of phosphate radical additive is in the scope of grams per liter salt solution, and it means within the scope of 1000ppm.
UK patent application No.2039959 discloses similar method, but replaces phosphoric acid to be added directly to salt solution, is mixed by phosphoric acid with the hypochlorous acid being added into salt solution termly and being used for balancing pH.In an embodiment, for the salt solution comprising about 35ppm calcium and 2ppmFe, in one case, they add the 1g-2g phosphoric acid (H of 85% 3pO 4the sodium chlorate that)/kg produces, and add 0.15g acid/rise ionogen in the latter case.This tittle is relatively high and with scope that previously scope of disclosure was similar in other reference.
The U.S. Patent application No.2008/0230381A1 of N.Krstajic etc. also discloses and adds the phosphate anion of at least 1g/l to serve as buffer reagent to sodium chloride brine.As negative electrode, Krstajic etc. propose and are coated with the soft steel substrate that thickness is the Fe-Mo alloy layer of the galvanic deposit of 10 μm-50 μm.When adding phosphate radical, Krstajic etc. mention, the viewed loss of voltage of coating of the activation of use the type can at 2.5-3kA/m 2conventional current density be issued to value up to 500mV, and use known salt solution, this reduction is limited to 100-150mV.Krstajic etc. also propose, and the dichromate concentration in ionogen can be reduced to 0.1g/l or eliminate completely, and significantly can not affect CE.
The problem of currently known methods is adopted to relate to the following fact: for the purpose of the calcium impurities removing the significant quantity in ionogen, in order to make calcium impurities reach level that they no longer affect negative electrode, add the phosphate radical additive of increasing amount.When also there is iron contamination in ionogen, a large amount of negatively charged ion such as PO 4 -3interpolation can cause other problem.In the paper being entitled as " EffectsofElectrolyteinChlorateCells ", R.A.Kus mentions, when iron exists with significant concentration level together with phosphate radical impurity, owing to affecting the synergy between these impurity of anode performance, observe voltage and raise.Due to this reason, industry is tended to not use phosphoric acid additive at present, because they almost all use iron cathode and therefore also have iron contamination except calcium impurities in their ionogen.
In view of the various challenges in sodium chlorate manufacture field, there are needs for providing the technology of at least some solution.
Summary of the invention
The present invention responds to above-mentioned needs by being provided for the technology of the enhancing manufacturing chlorizate such as sodium chlorate.
In some implementations, provide and comprise following electrochemical process: anode and negative electrode are arranged in the ionogen comprising the impurity comprising calcium ion; Between described anode and described negative electrode, voltage is applied form the condition of electrolysate in described ionogen under; Phosphate anion is provided to measure as follows: described amount is enough to form protectiveness skin on the cathode with calcium ion at least partially with in described ionogen; described protectiveness skin comprises calcium phosphate compound, and described amount is enough to substantially avoid calcium phosphate compound to precipitate in described ionogen.It should be noted that provide the step of phosphate anion can before executing alive step, afterwards or period carry out.
In some implementations, described phosphate anion adds with the amount of the surf zone contacted with described ionogen based on described negative electrode.
In some implementations, described technique applies described protectiveness skin before being included in further and being immersed in described ionogen by described negative electrode on catalytic middle layer.
In some implementations, apply the outer field step of described protectiveness and comprise dash coat, dip-coating, sol-gel, electrochemical deposition, bionical coating, the isobaric coating of heat or plasma spraying.
In some implementations, described technique forms described protectiveness skin after being included in further and being immersed in described ionogen by described negative electrode on catalytic middle layer.
In some implementations, form the outer field step of described protectiveness to comprise: in described ionogen, provide phosphate anion; Ensure to there is enough calcium ions in described ionogen; With the electrolytic condition being enough to cause the outer field formation of described protectiveness is provided.
In some implementations, the outer field formation of described protectiveness comprises: make Ca (OH) 2with H 3pO 4reaction is to produce Ca 3(PO 4) 2and water; With make Ca (OH) 2with Ca 3(PO 4) 2reaction is to produce Ca 10(PO 4) 6(OH) 2, wherein Ca 10(PO 4) 6(OH) 2form described protectiveness at least partially outer field.
In some implementations, the phosphate concentration being about 50ppm to be up to about 75ppm or about 5ppm-in described ionogen provides phosphate anion.
In some implementations, phosphate concentration is enough low to prevent on described anode O in iron phosphate compounds or sedimental formation, described ionogen 2the rising of level and/or the raising in voltage request.
In some implementations, phosphate anion is at least in part by H 3pO 4interpolation provided.Phosphate anion also can be provided by the intrinsic existence in described ionogen at least in part.Calcium ion also can be provided by the intrinsic existence in described ionogen at least in part.
In some implementations, described ionogen comprises for reacting first part's calcium ion to form calcium phosphate compound on the cathode with phosphate anion, and in described ionogen, keep unreacted second section calcium.
In some implementations, described technique is for the manufacture of chlorizate.Described chlorizate can comprise sodium chlorate and/or clorox.
In some implementations; there is provided phosphate anion in the purposes for manufacturing in the ionogen comprising calcium ion in the electrochemical process of chlorizate, wherein phosphate anion is that to be enough to be formed on negative electrode with calcium ion at least partially the protectiveness comprising calcium phosphate compound outer and be enough to avoid the amount that calcium phosphate compound precipitates in described ionogen to provide.
In some implementations, provide and comprise following electro-chemical systems: for comprising electrolytical tank room, wherein said ionogen comprises calcium ion and phosphate anion; Be arranged in the anode of described tank room; Be arranged in the negative electrode of described tank room; With ion-select electrode device; it is configured to regulate the ion concentration in described ionogen, described ionogen is comprised be enough to be formed on the cathode with calcium ion at least partially the protectiveness comprising calcium phosphate compound outer and be enough to the phosphate anion of the amount avoiding calcium phosphate compound to precipitate in described ionogen.
In some implementations, described ion-select electrode device comprises the entrance be communicated with described tank room fluid for being provided to by the phosphate anion of described amount in described tank room.Described ion-select electrode device can comprise at least one measuring apparatus of the concentration for measuring phosphate anion, iron ion and/or calcium ion in described ionogen further.Described ion-select electrode device also can comprise the controller being connected to described measuring apparatus and described entrance for controlling the input of phosphate anion in response to the reading from described measuring apparatus.Described system can be configured to for the manufacture of chlorizate such as sodium chlorate and/or clorox.
In some implementations, provide and comprise following electrochemical process: anode and negative electrode are arranged in the ionogen comprising the impurity comprising calcium ion and iron ion; Between described anode and described negative electrode, voltage is applied form the condition of electrolysate in described ionogen under; Phosphate anion is provided to measure as follows: described amount is enough to form protectiveness skin on the cathode with calcium ion at least partially with in described ionogen; described protectiveness skin comprises calcium phosphate compound, and described amount is enough to substantially avoid iron phosphate compounds to precipitate in described ionogen.
Above technique also can have other one or more features described in implementing as described in this article.
In some implementations; there is provided phosphate anion in the purposes for manufacturing in the ionogen comprising calcium ion and iron ion in the electrochemical process of chlorizate, wherein phosphate anion is that to be enough to be formed on negative electrode with calcium ion at least partially the protectiveness comprising calcium phosphate compound outer and be enough to avoid the amount that iron phosphate compounds precipitates in described ionogen to provide.
In some implementations, provide and comprise following electro-chemical systems: for comprising electrolytical tank room, wherein said ionogen comprises calcium ion, iron ion and phosphate anion; Be arranged in the anode of described tank room; Be arranged in the negative electrode of described tank room; With ion-select electrode device; it is configured to regulate the ion concentration in described ionogen, described ionogen is comprised be enough to be formed on the cathode with calcium ion at least partially the protectiveness comprising calcium phosphate compound outer and be enough to the phosphate anion of the amount avoiding iron phosphate compounds to precipitate in described ionogen.
In some implementations, provide and comprise following electrochemical process: anode and negative electrode are arranged in the ionogen comprising the impurity comprising calcium ion, described negative electrode has the surf zone contacted with described ionogen; Between described anode and described negative electrode, voltage is applied form the condition of electrolysate in described ionogen under; Phosphate anion is provided with the following predetermined amount of the described surf zone based on described negative electrode: described predetermined amount makes phosphate anion be consumed in the outer field formation of protectiveness of the surf zone contacted with described ionogen covering described negative electrode with calcium ion at least partially with in described ionogen.
In some implementations, the phosphate anion of described predetermined amount is about 0.025mg/cm 2negative electrode-Yue 0.2mg/cm 2negative electrode or about 0.05mg/cm 2negative electrode-Yue 0.15mg/cm 2negative electrode.
In some implementations, described ionogen comprises iron ion further, and phosphate anion is the amount interpolation avoiding iron phosphate compounds to precipitate in described ionogen further.Phosphate anion can be that the amount avoiding extra calcium phosphate compound to precipitate in described ionogen is added further.
In some implementations, the phosphate anion of described predetermined amount calculates based on the outer field target thickness of protectiveness to be obtained.
Above technique also can have other one or more features described in implementing as described in this article.
In some implementations; there is provided phosphate anion in the purposes for manufacturing in the ionogen comprising calcium ion in the electrochemical process of chlorizate, wherein phosphate anion provides with the following predetermined amount of the surf zone based on described negative electrode: described predetermined amount makes phosphate anion be consumed in the outer field formation of protectiveness of the surf zone contacted with described ionogen covering described negative electrode with calcium ion at least partially.
In some implementations, provide and comprise following electro-chemical systems: for comprising electrolytical tank room, wherein said ionogen comprises calcium ion and phosphate anion; Be arranged in the anode of described tank room; Be arranged in the negative electrode of described tank room; With ion-select electrode device; it is configured to regulate the ion concentration in described ionogen, makes described ionogen comprise the phosphate radical of the following predetermined amount of the surf zone based on described negative electrode: described predetermined amount makes phosphate anion be consumed in the outer field formation of protectiveness of the surf zone contacted with described ionogen covering described negative electrode with calcium ion at least partially.
In some implementations, provide prefabricated negative electrode, it comprises: substrate; Catalytic middle layer; Outer with the protectiveness comprising calcium phosphate compound.
In some implementations, described substrate comprises stainless steel.Described stainless steel can be 400 series stainless steels.Described substrate can comprise have be enough to prevent electrolyzer close down the phase during iron ion enter the material of electrolytical erosion resistance.
In some implementations, described catalytic middle layer adjoins with the outside surface of described substrate.
In some implementations, described catalytic middle layer comprises the metallic matrix doped with catalytic compound.Described metallic matrix can be iron aluminide.Described catalytic compound comprises Ru.
In some implementations, described calcium phosphate compound comprises hydroxyl calcium phosphate compound, such as hydroxyapatite.Described protectiveness skin can be made up of hydroxyapatite substantially.
In some implementations, described protectiveness skin has the thickness of about 0.25 micron of-Yue 1.5 microns.Described protectiveness skin can have the thickness of about 0.5 micron of-Yue 1 micron.
In some implementations, the whole outside surface that described protectiveness skin is arranged to cover described catalytic middle layer directly contacts with the calcium impurities in described ionogen to prevent described catalytic middle layer.Can by outer for described protectiveness dash coat, dip-coating, sol-gel applying, electrochemical deposition, bionical coating, the isobaric coating of heat or plasma spraying on described catalytic middle layer.
In some implementations, described protectiveness skin has network structure.Described protectiveness skin can have honeycomb structure.
In some implementations, described protectiveness skin has evolving hydrogen reaction lower can be occurred at it, prevent calcium impurities from poisoning the structure of described intermediate catalyst layer (Catalytic Layer) simultaneously.
In some implementations, described protectiveness skin has and makes it possible to stop chlorate anions and hypochlorite ion to arrive the surface of described intermediate catalyst layer to reduce or to avoid the structure of following reaction: ClO -+ H 2o+2e -=>Cl -+ 2OH -; And/or ClO 3 -+ 3H 2o+6e -=>Cl -+ 6OH -.
In some implementations, the purposes of prefabricated negative electrode as defined herein in the electrolyzer for the manufacture of chlorizate such as sodium chlorate and/or clorox is provided.
In some implementations, provide and comprise following electrochemical process: anode and prefabricated negative electrode as defined herein are arranged in the ionogen comprising the impurity comprising calcium ion; And between described anode and described prefabricated negative electrode, apply voltage under the condition forming electrolysate in described ionogen.This technique also can comprise the one or more of feature as described in this article.
In some implementations, be provided for manufacturing the method for the prefabricated negative electrode be used in the manufacture of chlorizate, comprise: substrate is provided; The top of described substrate provides catalytic middle layer; Be applied on described catalytic middle layer with by protectiveness skin, wherein protectiveness skin comprises calcium phosphate compound.
Described method can be carried out to manufacture the prefabricated negative electrode with one or more feature as described in this article.
In some implementations, apply the outer field step of described protectiveness and comprise dash coat, dip-coating, sol-gel process, electrochemical deposition, bionical coating method, the isobaric coating of heat and/or plasma spraying.
In some implementations, provide and comprise following electrochemical process: anode and negative electrode are arranged in the ionogen comprising the impurity comprising calcium ion, wherein said negative electrode comprises the substrate and catalytic middle layer that are made up of corrosion-resistant material; For the electrolysis phase, carry out electrolysis, it applies voltage under being included in the condition forming electrolysate in described ionogen between described anode and described negative electrode; Periodically described electrolysis closed down for the phase of closing down, it comprises and stops described voltage, the corrosion resistant material of wherein said substrate prevent described close down each of phase during iron ion be discharged in described ionogen; Phosphate anion is provided to measure as follows: described amount enough makes during each electrolysis phase with in described ionogen; it is outer that phosphate anion and at least partially calcium ion form or again formed protectiveness on the catalytic middle layer of described negative electrode, and described protectiveness skin comprises calcium phosphate compound.
Above technique also can have other one or more features described in implementing as described in this article.
In some implementations, provide and comprise following electrochemical process: anode and negative electrode are arranged in the ionogen comprising the impurity comprising alkaline-earth metal ions; Between described anode and described negative electrode, voltage is applied form the condition of electrolysate in described ionogen under; Phosphate anion is provided to measure as follows: described amount is enough to form protectiveness skin on the cathode with alkaline-earth metal ions at least partially with in described ionogen; described protectiveness skin comprises alkali earth metal phosphate compound, and described amount is enough to substantially avoid alkali earth metal phosphate compound to precipitate in described ionogen.Described alkaline-earth metal can be calcium.Also note, the various enforcements of technique described herein can be carried out for the common alkaline-earth metal being different from concrete calcium.
In some implementations, provide and comprise following electrochemical process: anode and negative electrode are arranged on and comprise in the ionogen of impurity; Between described anode and described negative electrode, voltage is applied form the condition of electrolysate in described ionogen under; In described ionogen, following enough phosphate anions and calcium ion is there is: it makes phosphate anion and calcium ion at least partially form protectiveness skin on the cathode with ensureing; described protectiveness skin comprises calcium phosphate compound, and it is substantially avoided calcium phosphate compound to precipitate in described ionogen, substantially avoids iron phosphate compounds precipitate in described ionogen and/or consume substantially all phosphate anions in the outer field formation of described protectiveness when there is iron ion in described ionogen.
Also note, by technique, system, purposes, negative electrode and manufacture one or more further optional features of method of negative electrode, aspect and enforcement and can combine with various enforcement described above in greater detail in the following description.
Accompanying drawing explanation
Fig. 1 is the schematic diagram of the electrolytic system for the manufacture of sodium chlorate.
Fig. 2 is O 2content, voltage and efficiency are to the figure of time.Efficiency curve is top curve; Voltage curve is intermediate curve; And O 2content is bottom curve.
Fig. 3 is to the figure of 2 θ (degree) from the counting (arbitrary unit) of the x-ray scanning of cathode surface.
Fig. 4 is the chlorate anions electrolyzer for being added with calcium, the figure of current versus time.
Fig. 5 be added into ionogen in electrolysis with by calcium and phosphoric acid after from the counting (arbitrary unit) of the X-ray diffraction spectrum of cathode surface to the figure of 2 θ (degree), illustration is the EDX spectrum of the element that display cathode surface exists.
Fig. 6 is O 2content, voltage and efficiency are to another figure of time.Efficiency curve is top curve; Voltage curve is intermediate curve; And O 2content is bottom curve.
Fig. 7 a and 7b is the electron scanning micrograph of the cross section of cathode structure.
Fig. 8 is a pair electron scanning micrograph of the cross section of cathode structure.
Fig. 9 is the outer field a pair photomicrography chemical graph (map) of protectiveness.
Figure 10 is when the calcium of the difference amount of adding to ionogen, the figure of current versus time.
Figure 11 is at interpolation calcium ion, when adding phosphoric acid afterwards, and the figure of current versus time.
Figure 12 is at interpolation phosphoric acid, when adding calcium ion afterwards, and the figure of current versus time.
Figure 13 is when adding phosphoric acid, the figure of current versus time.
Figure 14 is block diagram.
Embodiment
In electrolytic system, the phosphate radical of relatively small amount is used to form protective layer on negative electrode for the various technical supports described by electrolysis herein.Further technology is provided for electrolysis and manufactures chlorizate such as sodium chlorate (NaClO 3or ClO 3 -) (it is the compound used in paper bleaching application) or clorox (NaClO or ClO -) the prefabricated negative electrode with the protective layer comprising calcium phosphate compound in (it is water conditioner).Although should be understood that herein will about manufacture sodium chlorate discuss various enforcement and in, such technology can be suitable for manufacturing other chlorizate such as clorox etc.
In some implementations; sodium chlorate is manufactured by being strengthened as follows: provide the protectiveness comprising calcium phosphate compound outer to negative electrode by electrolysis; it is by being formed to measure interpolation phosphate anion as follows: described amount causes forming calcium phosphate compound in the surface of negative electrode, prevents can having the iron phosphate compounds of harmful effect and/or the precipitation of calcium phosphate compound to electrolysis simultaneously.Outer in order to form described protectiveness, phosphate radical can be provided based on the amount of the surf zone of negative electrode.
Although other method highlighted by make calcium ion to be precipitated out from ionogen for the purpose of add the phosphate anion of higher level, various technology described herein provides the favourable interpolation of the phosphate anion being enough to the reduction forming protective layer on cathode surface.In some cases; level that can be significantly low provides phosphate anion to form protective layer; although this not only makes residual calcium ion in ionogen also realize the operation of electrolysis improvement, and reduces or prevent the formation can with the iron phosphate compounds of negative impact.Therefore, although ionogen can have plurality of impurities such as calcium ion and iron ion, described protectiveness skin can provide protection from ionogen impurity effect and the electrolysis procedure of remaining valid.
In some cases, the phosphate concentration that the useful aspect of phosphate radical additive can be such realizes: its one or more magnitude lower than the concentration used in the past.Replace to add phosphate radical according to the calcium ion concn in ionogen to make calcium impurities be precipitated as object, object can be the following is to provide phosphate radical: form calcium phosphate protective layer to offset the negative impact in aseptate sodium chlorate electrolysis bath on calcium anticathode surface.
When with comprise substrate such as stainless steel and catalytically active coatings such as use as the cathode combination of the metallic matrix of Ru doped with catalytic species time, provide such protective layer can be particularly advantageous.In evolving hydrogen reaction (equation 2) process, calcium impurities can disturb such catalytically active coatings and form calcium hydroxide, causes bath voltage to raise gradually along with the sedimental accumulation of this hoodwinking property.The condition of the deposition causing insoluble calcium phosphate compounds such as hydroxyapatite can be provided near cathode surface.Even if the average pH in bulk electrolysis matter remains near 6.5, owing to forming hydroxyl according to equation 2, the pH near cathode surface is also much higher, such as, far above 10.The pH that local raises makes the local solubility of calcium phosphate compound reduce and causes the formation of settled layer.In addition, calcium hydroxide physiographic relief be formed in negative electrode surface on and these bunches of calcium hydroxide can serve as calcium phosphate (Ca 3(PO 4) 2) the seed of formation.When there is a small amount of phosphoric acid near cathode surface, there is following reaction:
3Ca(OH) 2+2H 3PO 4＝>Ca 3(PO 4) 2+6H 2O(12)
These calcium phosphate molecules further according to following with calcium hydroxide reaction to form hydroxyapatite on cathode surface:
Ca(OH) 2+3Ca 3(PO 4) 2＝>Ca 10(PO 4) 6(OH) 2(13)
High temperature (about 60 DEG C-Yue 85 DEG C) as the feature of chlorate anions operation is also conducive to this deposition, because temperature is higher, the solubleness of calcium phosphate compound is lower.In fact, the condition that heterogeneous (heterogeneous, the heterogeneous) that be provided for the hydroxyapatite on cathode surface is formed, even if they can be not suitable for the precipitation of phosphate compounds in electrolytical body.Various technical support described herein by such condition for predetermined add phosphate radical with in the formation of the calcium phosphate protective layer on cathode surface by completely consumed substantially.Also note, one or more other calcium phosphate compounds such as Ca 3(PO 4) 2also can exist and there is useful protective nature.
Below will describe various aspect of the present invention, comprise for the manufacture of the system of sodium chlorate and technique, prefabricated negative electrode and purposes and the method manufacturing prefabricated negative electrode.
For the electrolytic system that sodium chlorate manufactures
Fig. 1 schematically illustrates the system 10 for the manufacture of sodium chlorate.System 10 comprises electrolyzer 12, and electrolyzer 12 has tank room 14, and tank room 14 is filled with electrolyte solution 16 (in this article also referred to as ionogen).System 10 also comprises anode 18 and negative electrode 20, and its possible structure and composition will be discussed hereinafter further.Negative electrode 20 can have the structure comprising substrate 22, intermediate catalyst layer 24 and protectiveness skin 26.
Still with reference to Fig. 1, electrolyzer 12 produces the solution 28 being rich in sodium chlorate, and it is taken out from tank room 14 and can be provided to downstream units 30 such as settling vessel, strainer, vaporizer, crystallizer and moisture eliminator for processing to produce the sodium chlorate 32 of solid and/or conc forms further.
Negative electrode 20 (it also can be called cathode structure) can comprise three or more layers.In some cases, described cathode structure has and comprises following three layers: substrate 22, is set directly at the intermediate catalyst layer 24 in substrate 22, and is set directly at the protectiveness skin 26 on intermediate catalyst layer 24.Also can expect providing one or more layer in addition in the middle of different layers.
In some implementations, substrate 22 such as can be made up of from the stainless steel of 400 series corrosion resistant material.More contents about substrate will further describe hereinafter.
In some implementations, intermediate catalyst layer 24 can by the highly active catalytic material of high porosity such as Fe 3al (Ru) and Fe 3alTa (Ru) forms.More contents about intermediate catalyst layer will further describe hereinafter.
In some implementations, protectiveness skin 26 comprises calcium phosphate compound.More contents about the outer field formation of protectiveness and character will further describe hereinafter.
The formation of phosphate radical dosing (dosing) and protective layer
Described protectiveness skin can be formed in many ways.In a kind of situation, the outer original position formation in electrolyzer of described protectiveness.In other situation, described protectiveness skin dystopy (exsitu) can form to manufacture the prefabricated negative electrode that can be used in electrolytic system.More contents about prefabricated negative electrode and dystopy method will further describe hereinafter.
As implied above, described protectiveness skin can in electrolyzer by add phosphate anion and in some cases calcium ion and original position formation.
Phosphate anion can be enough to be formed described protectiveness outer and avoid one or more other react the relatively low amount interpolation that such as calcium or iron ion deposit from bulk electrolyte solution precipitation and/or iron phosphate compounds at anode.
With regard to being added into the amount of electrolytical phosphate anion, this can be depending on and comprises following many factors: the thickness of the surf zone (surface-area) of negative electrode to be protected, protective layer to be formed, the Nomenclature Composition and Structure of Complexes of electrode, electrolytical composition and character etc.
In some cases, phosphate radical be enough to be formed have about 0.25 micron of-Yue 1.5 microns, about 0.5 micron of-Yue 1 micron or about 0.6 micron-Yue 0.9 micron thickness protective layer amount add.Fig. 8 illustrates and is formed on catalytic middle layer and has the protective layer that usual scope is the thickness of about 0.5 micron of-Yue 1 micron.
In addition, can follow total criterion, the amount being added into electrolytical phosphate radical is thus enough to be formed the protective layer with about 1 micron thickness at the most.Such as, in a kind of situation discussed in following examples part, about 0.1mg phosphate radical (PO can be added 4)/cm 2negative electrode.It is therefore to be understood that the amount of phosphate radical to be added can be determined based on the amount of the calcium ion existed in the surf zone of negative electrode instead of electrolytical volume or ionogen.Such as, the amount of phosphate radical to be added can be about 0.025mg/cm 2negative electrode-Yue 0.2mg/cm 2negative electrode or such as 0.05mg/cm 2negative electrode-Yue 0.15mg/cm 2negative electrode.
In addition, the amount of phosphate radical to be added pre-determines, as understood from embodiment by calculating and/or empirical test.In an example, in order to form protective layer on negative electrode, add the phosphate anion being no more than 75ppm, 50ppm, 30ppm, 20ppm or 15ppm to ionogen.
In some cases, described ionogen can not comprise at first and forms calcium ion enough for protective layer for phosphate anion.The interpolation of calcium ion can before the interpolation of phosphate anion, period or afterwards with for allowing that forming enough amounts for protective layer carries out.Figure 11 and 12 illustrates, raises stop to make voltage, and calcium ion and phosphate anion can multiple order add.
It shall yet further be noted that phosphate radical can be used as dose and adds or can periodically add with cumulative dosage.Figure 13 illustrates within one period increasingly by situation that multiple phosphate radical dosage adds to described system.
Back with reference to Fig. 8, can see that protective layer is porous, there is reticulattion shape or honeycomb structure, the network of void space that described structure has structural unit (structuralelements) and to disperse.In some cases, the porosity of protective layer and perviousness low to being enough to protect catalytic layer below to poison from calcium and being high enough to avoid hindering evolving hydrogen reaction to occur.
Briefly back with reference to Fig. 1, phosphate radical can be added pipeline 34 via one or more phosphate radical and be added into ionogen 16, described phosphate radical adds pipeline 34 and can be independent pipeline or can be configured to phosphate radical to be added into another entrance of electrolyzer 12, such as, as directed rare HCL entrance.Can manually or automatic powder adding add phosphate radical.It can be and adds in response to about the measuring result acquired by electrolytic system or reading.In this sense, phosphate radical pipeline 34 can be a part for ion-select electrode device, and the amount of the phosphate anion in the adjustable ionogen of described ion-select electrode device and possibly calcium ion is to ensure to provide a small amount of phosphate radical being enough to form protective layer.Described ion-select electrode device can have other parts various such as measuring apparatus and controller.
In some implementations, phosphate radical is with phosphoric acid H 3pO 4formation add.But, it should be noted that phosphate radical can such as acid or salt in other forms, with monophosphate or polyphosphate compounds or add in other forms.
In addition, the interpolation of phosphate radical can be carried out to promote the completely consumed substantially of phosphate radical in the formation of protective layer.Such as, the condition (such as electrolytical temperature, pH, composition etc.) controlling electrolytic system can limit or prevent any other from relating to the reaction of phosphate radical with the formation being supported in calcium phosphate compound on cathode surface.This rate-determining steps can electrolysis procedure beginning or near carry out, protective layer can be formed as quickly as possible.As will be described further below, also can making in many ways negative electrode protective layer dystopy to be applied, making the negative electrode when starting electrolysis procedure have protective layer.
Prefabricated negative electrode and dystopy manufacture
Described prefabricated negative electrode can comprise substrate, catalytic layer and protective layer.Prefabricated negative electrode described herein can be used for the iron cathode replacing using at present in industry, to provide erosion resistance, the high activity to evolving hydrogen reaction, good hydrogen current efficiency and low hydrogen overpotential.In some cases, described prefabricated negative electrode not catalysis hypochlorite and chlorate anions reduction and do not produce significant oxygen gas by-products.
Described prefabricated negative electrode can provide some advantages, such as, provide the protective coating of catalytic layer when electrolysis procedure starts and provide the tolerance to ionogen impurity, and contributes counteracting negative effect of calcium impurities on cathode surface.
The method manufacturing described prefabricated negative electrode can comprise by dash coat, dip-coating, sol-gel process, electrochemical deposition, bionical coating, the isobaric coating of heat or plasma spraying and apply the outer field step of described protectiveness.The method can selected and implement to apply described protective layer to obtain the properties of described protective layer, such as, thickness within the scope of some, perviousness and porosity.
With reference to Figure 14, the cathode structure 36 that can comprise substrate and catalytic layer can be supplied to the dystopy pretreatment unit 38 for applying protective layer.Pretreatment unit 38 can be configured to carry out one or more of the aforesaid method for applying protective layer, thus manufactures prefabricated negative electrode 20.Then prefabricated negative electrode 20 is supplied to the electrolyzer 12 for the manufacture of sodium chlorate.
In some cases, described prefabricated negative electrode can keep in a cell until their working life terminates.If the protective coating applied in advance is destroyed or partly remove, then can uses the in-situ method that described protective layer regenerates, such as, add the phosphate radical of predetermined amount as described in this article.In addition, in some cases, after the operation of certain period, ionogen can be removed and by cleaning this electrolyzer as follows from electrolyzer 12: introduce weak acid (mildacid) liquid, it is provided about 1 hour in a cell usually.If carry out removing outer field clean or other attended operation like this of described protectiveness from described negative electrode, then original position can again apply described protectiveness skin to make to realize sustainable protection during the next stage of electrolysis.
Alternatively, after the operation of certain period, can shift out to carry out cleaning and/or safeguarding from electrolyzer 12 by with the negative electrode 40 crossed.Can such as be moved out of closing down between working life of electrolyzer 12 with the negative electrode crossed.Cleaning unit 42 can will be provided to the negative electrode 44 checked and clean described negative electrode cleans to produce warp with the negative electrode 40 crossed.Cleaning course can remove described protective layer from cathode structure and therefore can be supplied to pretreatment unit 38 again to apply described protective layer by through clean negative electrode 44, and described negative electrode can be reused immediately following upon release thereof in described electrolyzer.
Cathode substrate and catalytic layer
In some implementations, as mentioned before, described negative electrode has the structure comprising substrate and catalytic layer.
Described substrate can comprise not nickeliferous stable corrosion-resistant substrate.Described substrate can be the stainless steel of 400 series or the other material with corrosion resistance properties.The stainless steel of 400 series can be used, although have higher cathode overpotential.As listed as shown in the stainless following table 1 of the business that can obtain from AKSteel company, these alloys have with those similar low-down carbon contents of mild steel and do not have nickel.They are corrosion resistant at the medium camber of chloride ion-containing.In electrolysis procedure, etching problem can be occurred when there is not galvanic protection during closing down, and mild steel negative electrode can suffer deterioration.Upper layer can remove when each power failure by the corrosion product on steel.Although the calcium be still present in ionogen and phosphate radical can cause the regeneration of described protective layer, another favorable characteristics is to provide the substrate of improvement compared with mild steel.
Table 1: the business stainless steel that can obtain from AKSteel company
Described Catalytic Layer can comprise the metallic matrix doped with catalytic activity compound.Such as, described catalytic layer can comprise Fe 3al (Ru) and Fe 3alTa (Ru), it can be used for manufacturing sodium chlorate and having improvement relative to iron.These materials have the catalytic species (Ru) in iron aluminide metallic matrix.Although they are for the efficiency of evolving hydrogen reaction, unfortunately, these new cathode materials also affect by calcium impurities.As shown in Figure 4, in the electrolyzer comprising these alloys, after adding 2ppm calcium impurities to ionogen, the voltage observing 60mV raises.Doped calcium thing on negative electrode tends to poison this electrode and the activity reducing catalytic species.This voltage raises and occurs in the time scale of a hour instead of the time scale of several months, and this is than fast on conventional cathodes.Its reason comes from the following fact: these negative electrodes are highly porous.They typically have the effective surface about 100 times of high effective surfaces for steel negative electrode.Therefore, the hoodwinking property settling on surface at a good pace can block a large amount of catalytic site in the hole being positioned at catalytic structure body.But, the use comprising the protective layer of calcium phosphate compound make described catalytic layer can provide useful operation and not poison by calcium impurities.
In order to have enough life-spans, negative electrode should be able to stand power failure.When there is not cathodic current protection, the severeest etching condition occurs during power failure of being everlasting.
In some cases, described prefabricated negative electrode has the structure can standing repeatedly current interruptions.
Various aspect described herein and enforcement provide such as following advantage: the negative impact etc. of the antianode of the maintenance of the phosphate radical demand of minimizing, the operating time extended between electrolyzer cleans, low voltage level, the enhancing protection of negative electrode, reduction.
Embodiment and experiment
Present various embodiments and experimental result will be described.
Fig. 2 is presented at and uses iron cathode and DSA anode at 70 DEG C and 2.5kA/m 2a series ofly to close down in the chlorate anions electrolyzer of operation.Ionogen comprises the NaClO of 550g/l 3, 110g/l the dichromate of NaCl and 3g/l.To reaching 2,5,10 and 15 minutes with the current interruptions of (open circuit) (OC) form of opening a way and reaching 15 minutes with the interruption of short circuit (CC) form and observe afterwards.In open circuit, negative electrode at a good pace reaches its corrosion potential being positioned at 1.08V place relative to the voltage of DSA.Interrupt longer, the release of oxygen burst is larger and CE after closing down is lower.When interrupting occurring under CC condition (it is equivalent to bi-polar configuration), the so serious so that large shell of corrosion product of corrosion drops on the bottom of electrolyzer and result, and the oxygen release after this event is relatively little.
The x-ray scanning that Fig. 3 obtains from cathode surface after being presented at the electrolysis several months.Except sodium chlorate, also observe calcium hydroxide (portlandite) and some calcium sulfate hydroxides (calcium sodium alum) settling.
These hoodwinking property settlings are the reasons causing the bath voltage observed after prolonged operation to raise.
Embodiment 1
The anticathode beneficial effect of interpolation of very small amount of phosphate radical additive is observed in following experiment.
The NaClO of 550g/l will be comprised 3, 110g/l NaCl and 3g/l dichromate 350 liters of electrolytical body lotions of sodium chlorate be used for electrolysis.PH and temperature are remained on 6.5 and 70 DEG C respectively.Use steel negative electrode and DSA anode in an experiment.With 2.5kA/m 2after continuous electrolysis 74 hours, bath voltage is 3.056 volts.Then with CaCl 2form adds 4ppm calcium impurities and only in 1 hour, voltage rises to 3.074, this means the rising of 18mV to ionogen.Carry out not having the event of closing down for 15 minutes of galvanic protection (that is, Kai Lu – OC) to cause some corrosion of negative electrode and to produce iron contamination in the electrolyte and at continuous electrolysis after 22 hours, voltage reaches 3.060 volts.This voltage is close to original value, and this shows, the surface impurity on cathode surface and a part for corrosion product are removed by this event sequence (closing down with OC, hydrogen is released afterwards).
Afterwards, carry out 15 minutes close down with the second time of the form of open circuit and during this event, by 10ml phosphoric acid (H 3pO 4– 85%) be added into this 350 liters of ionogen.Consider the density of ionogen 1.3g/l and the density of phosphatase 11 .7g/l, this interpolation corresponds to phosphate anion (PO 4 -3) be 0.047g/l or 36ppm to ionogen.This is also equivalent to the phosphorus of 15.3mg/l in ionogen.This considerably less phosphate compounds is added and is caused the large voltage drop of 62mV after perseverance polarizes 22 hours, as gather this serial experiment table 2 as shown in.Finally, the second time of carrying out 10ml phosphoric acid during another of 15 minutes closes down event is added, and observes the other voltage drop of 71mV after 16 hours in electrolysis.From being 147mV adding the total voltage drop (3.074 to 2.927volt) the value observed after calcium impurities.Add for corresponding to the considerably less phosphate anion being less than 0.1g/l or 75ppm, this is large decline.Under these low-down levels of phosphate radical in the electrolyte, there is not the precipitation (it is as mentioned before, can be harmful to the overall operation of electrolyzer) of the iron phosphate compounds be positioned on anode.
Table 2: the chain of events that the part as electrolytic experiment is carried out
After above-mentioned experiment, foreign matter content analysis is carried out to ionogen and result is shown in Table 3.
Table 3: the foreign matter content after experiment in body lotion
Ca P Fe
Foreign matter content (mg/l) 2.9 19 4.3
Due to the phosphorus of 4ppm calcium and total 30.6mg/l (twice of the amount of 15.3mg/l) is added into ionogen, table 3 shows, and still there is the impurity of significant quantity at the end of experiment in the electrolyte.Due to the protective coating on cathode surface, the residual calcium impurities in body lotion no longer affects bath voltage.
By the X-ray diffraction spectrum of negative electrode from the surface of this electrode after body lotion shifts out at the end of Fig. 5 is presented at experiment.Before analysis that this surface is dry in atmosphere.This spectrum have clearly revealed from hydroxyapatite Ca 10(PO 4) 6(OH) 2the phosphoric acid calcium oxide Ca of dehydration 10(PO 4) 6the existence of O.This proves, there is the thin layer of hydroxyapatite in chlorate anions electrolyzer when there is calcium impurities and very small amount of phosphate radical in the electrolyte on the surface of negative electrode.This thin layer of hydroxyapatite is protected cathode surface from the harmful effect of calcium impurities and is caused the remarkable reduction of bath voltage.Lower than under the phosphate concentration of 0.1g/l or 75ppm, exist for promoting that the condition of the formation of the hydroxyapatite at cathode surface place (comprises high pH, high temperature and Ca (OH) 2the existence of seed), being namely used in the condition that calcium phosphate compound precipitates in ionogen body can be not enough.Therefore, calcium ion can still be present in ionogen with quite high concentration, but their anticathode negative impacts are lowered due to hydroxyapatite protective layer.In addition, phosphorus acid ion concentration is low to being enough to avoid forming iron phosphate compounds on the anode surface.
Embodiment 2
Fig. 6 display is except using electrochemical test similar with the electrochemical test that shows in Fig. 2 except stainless steel cathode.Particularly, Fig. 6 is presented at the stainless steel cathode of 400 series and DSA anode at 70 DEG C and 2.5kA/m 2a series of in the chlorate anions electrolyzer of lower operation are closed down.To reaching 2,5,10 and 15 minutes with the current interruptions of (OC) form of opening a way and reaching 15 minutes with the interruption of short circuit (CC) form and observe afterwards.As found out by being compared by Fig. 6 and Fig. 2, the electrolyzer with stainless steel cathode has the current potential of the current potential height 190mV than electrolytic iron groove (4.42 – 4.23 volts).As previously mentioned, this causes owing to there is chromium in Stainless Steel Alloy.Background O 2release also exceeds 0.4% (3.1% to 2.7%) slightly.But surprisingly, even if the cathode efficiency of stainless steel cathode is much higher and also remain high during current interruptions.
Even if this is owing to being also that stable stainless steel surface causes under etching condition.In open circuit, form highly stable passive surface layer on stainless steel.This passive surface layer with by adding dichromate in the electrolyte and formed and provide the hydroxide layers of chrome of high cathode efficiency similar.In Stainless Steel Alloy, therefore the existence of chromium provides high current efficiency all the time, and when mild steel negative electrode, closes the stopping time in existence at every turn, and ferriferous oxide dirt makes current efficiency significantly reduce.And on Fig. 6 be significantly, the open circuit voltage of stainless steel electrolytic groove is more much lower than the open circuit voltage of electrolytic iron groove (0.35 to 1.08 volts), this shows, stainless steel is than mild steel more inertia and result, and the galvanic corrosion under bipolar or short circuit condition will significantly reduce.In addition, stainless high erosion resistance makes the total amount of the iron contamination in chlorate anions ionogen reduce and result, is reduced on anode and forms the phosphatic possibility of iron.
In order to overcome the higher shortcoming of stainless overpotential, this stainless steel-based end, can be easy to thin catalytic layer coating with making the evolving hydrogen reaction described in equation 2.The example of such catalytic layer is Fe 3al (Ru) and Fe 3alTa (Ru) alloy.
Fig. 7 a and 7b shows the electron scanning micrograph taken from the stainless steel-based end comprising 400 series and the cross section of such cathode structure of the thin catalytic top layers of type that describes before.
In order to complete the cathode structure according to one embodiment of the present invention, the top of this bilayer is added the coating of this electrode of protection from the impurity effect in ionogen.The hydroxyapatite protective layer described before this top surface layer can be.
The example of whole cathode structure comprises: (i) comprises a small amount of carbon and the stainless steel-based end of 400 not nickeliferous series; (ii) catalytic middle layer such as based on doped with catalytic element such as Ru iron-aluminide metallic matrix and as in Canadian Patent file No.2687129 and/or 2778865 describe catalytic middle layer; (iii) top layers of the impurity effect existed in comprising hydroxyapatite or being substantially made up of to protect negative electrode from ionogen hydroxyapatite on the surface in described catalytic middle layer.
As previously discussed, the top layers of the hydroxyapatite on cathode surface is by introducing the compound of a small amount of phosphorous acid group in the electrolyte (such as to be less than 0.1g/l or 75ppm phosphate anion (PO 4 -3) amount) and original position formed.This upper layer of hydroxyapatite is also by following and dystopy preparation: before being used in by electrode assemblie in electrochemistry chlorate anions electrolyzer, deposit this coating.In fact, by comprising the coating of following some method deposited hydroxyl apatites: thermal spray, dash coat, dip-coating, sol-gel, electrochemistry and electrophoretic deposition, bionical coating and the coating of heat equipressure.The most frequently used method of manufacture hydroxyapatite coating layer is the plasma spraying by being classified as thermal spray techniques.
Embodiment 3
Fig. 8 display is from two electron scanning micrographs of cross section shooting of cathode structure comprising the stainless steel-based end of 400 series, catalytic middle layer and thin hydroxyapatite top layers.Note, before carrying out electron microscope method, on the top of sample, provide tungsten coating to protect sample during processing.
Fig. 9 shows the chemical graph of hydroxyapatite layer, and it shows to there is calcium and phosphoric.
Embodiment 4
At room temperature, when the calcium impurities of the difference amount of adding to ionogen to comprising Fe 3the electrolyzer of Al (Ru) type negative electrode is tested.It may be noted that when adding 1-2ppm calcium only raising 100-150mV in 1 or 2 hour, showing the negative impact of calcium to such electrode.Figure 10 shows the result of these tests.
Embodiment 5
Figure 11 display for the electrolyzer comprising the electrode that such catalysis strengthens at the temperature of 68 DEG C along with the voltage of time lapse.After electrolysis about 4 minutes, add the Ca of 2ppm to ionogen + 2ion.Then voltage systematically raise.After electrolysis about 45 minutes, add phosphate anion PO4 with the form of phosphoric acid -3.Effect is that the rising of bath voltage is stopped immediately.
Embodiment 6
In another test reported in such as Fig. 2, for except wherein before adding calcium ion, phosphoric acid is added into except ionogen with similar electrolyzer in embodiment 5, display voltage develops.After electrolysis about 2 hours, add 2ppmCa + 2.The remarkable rising of voltage is not observed after this interpolation of calcium.
Embodiment 7
Figure 13 illustrates the low level of the phosphate radical that can prevent negative (pole) voltage caused by calcium impurities from raising.Calcium exists with the amount of about 2ppm.
Embodiment 8: the calculating added for phosphate radical is estimated
As discussed above, phosphate radical or otherwise provide phosphate radical can be added based on the surf zone treating to be covered by protective layer of negative electrode to ionogen.
When phosphate radical being added into ionogen to form protective layer wherein, the amount of phosphate radical can be determined in many ways.In an example, phosphate radical adds is predetermined based on computing methodology such as computing methodology described below.
Can measure or obtain from document the various character of calcium phosphate compound, such as:
The molecular formula of hydroxyapatite: Ca 5(PO 4) 3oH;
The molecular weight of hydroxyapatite: 502.31g;
Phosphate radical (PO in hydroxyapatite 4) massfraction (284.91/502.31): 56.7%;
The bulk density (100% is fine and close) of hydroxyapatite: 3.156g/cc; With
Porous hydroxyapatite can have the porosity (0.35g/cc=>89%, from document) being up to 90%.
So the maximum phosphate radical demand on negative electrode can calculate as follows:
Assuming that the protective layer of about 1 micron thickness will be obtained, because have been found that this thickness is enough to provide protective nature;
For 1cm 2the volume of surface=> layer: 10 -4cm 3;
Every cm 2phosphate radical quality (100% the is fine and close)=>3.156g/ccx10-4ccx56.7%=0.179mg of cathode surface;
Therefore, can provide and be less than 0.18mg phosphate radical (PO4)/cm 2cathode surface; With
If the hydroxyapatite surface layer with 1 micron thickness of 45% porosity is enough to stop calcium to poison catalytic middle layer, then will need the phosphate radical (PO of 0.18mgx (1-0.45)=0.1mg 4)/cm 2negative electrode.

Claims (114)

1. electrochemical process, comprising:
Anode and negative electrode are arranged in the ionogen comprising the impurity comprising calcium ion;
Between described anode and described negative electrode, voltage is applied form the condition of electrolysate in described ionogen under; With
Phosphate anion is provided to measure as follows: described amount is enough to form protectiveness skin on the cathode with calcium ion at least partially in described ionogen; described protectiveness skin comprises calcium phosphate compound, and described amount avoids calcium phosphate compound to precipitate in described ionogen substantially.
2. the electrochemical process of claim 1, wherein phosphate anion adds with the amount of the surf zone contacted with described ionogen based on described negative electrode.
3. the electrochemical process of claim 1 or 2, is included in further before being immersed in described ionogen by described negative electrode on catalytic middle layer, applies described protectiveness skin.
4. the electrochemical process of claim 3, wherein applies the outer field step of described protectiveness and comprises dash coat, dip-coating, sol-gel, electrochemical deposition, bionical coating, the isobaric coating of heat or plasma spraying.
5. the electrochemical process of claim 1 or 2, is included in further after being immersed in described ionogen by described negative electrode on catalytic middle layer, forms described protectiveness skin.
6. the electrochemical process of claim 5, wherein forms the outer field step of described protectiveness and comprises:
Phosphate anion is provided in described ionogen;
Ensure to there is enough calcium ions in described ionogen; With
The electrolytic condition being enough to cause the outer field formation of described protectiveness is provided.
7. the electrochemical process of any one of claim 1-6, the outer field formation of wherein said protectiveness comprises:
Make Ca (OH) 2with H 3pO 4reaction is to produce Ca 3(PO 4) 2and water; With
Make Ca (OH) 2with Ca 3(PO 4) 2reaction is to produce Ca 10(PO 4) 6(OH) 2, wherein Ca 10(PO 4) 6(OH) 2form described protectiveness at least partially outer field.
8. the electrochemical process of any one of claim 1-7, wherein provides phosphate anion with the phosphate concentration being up to about 75ppm in described ionogen.
9. the electrochemical process of any one of claim 1-7, wherein phosphate concentration is about 50ppm for about 5ppm-.
10. the electrochemical process of any one of claim 1-9, wherein phosphate concentration is low to being enough to prevent from forming iron phosphate compounds or settling on described anode.
The electrochemical process of 11. any one of claim 1-10, wherein phosphate concentration is low to being enough to prevent the O in described ionogen 2the rising of level.
The electrochemical process of 12. any one of claim 1-11, wherein phosphate concentration is low to being enough to the rising preventing voltage request.
The electrochemical process of 13. any one of claim 1-12, wherein phosphate anion is at least in part by H 3pO 4interpolation provided.
The electrochemical process of 14. any one of claim 1-13, wherein phosphate anion provided by the intrinsic existence in described ionogen at least in part.
The electrochemical process of 15. any one of claim 1-14, wherein calcium ion provided by the intrinsic existence in described ionogen at least in part.
The electrochemical process of 16. any one of claim 1-15, wherein said ionogen comprises for reacting first part's calcium ion to form calcium phosphate compound on the cathode with phosphate anion, and in described ionogen, keep unreacted second section calcium.
The electrochemical process of 17. any one of claim 1-16, wherein said technique is for the manufacture of chlorizate.
The electrochemical process of 18. claims 17, wherein said chlorizate comprises sodium chlorate and/or clorox.
The electrochemical process of 19. claims 17, wherein said chlorizate is sodium chlorate.
20. phosphate anions are in the purposes for manufacturing in the ionogen comprising calcium ion in the electrochemical process of chlorizate, and wherein phosphate anion is that to be enough to be formed on negative electrode with calcium ion at least partially the protectiveness comprising calcium phosphate compound outer and be enough to avoid the amount that calcium phosphate compound precipitates in described ionogen to provide.
The purposes of 21. claims 20, wherein said chlorizate comprises sodium chlorate and/or clorox.
22. electro-chemical systems, comprising:
For comprising electrolytical tank room, wherein said ionogen comprises calcium ion and phosphate anion;
Be arranged in the anode of described tank room;
Be arranged in the negative electrode of described tank room; With
Ion-select electrode device; it is configured to regulate the ion concentration in described ionogen, described ionogen is comprised be enough to be formed on the cathode with calcium ion at least partially the protectiveness comprising calcium phosphate compound outer and be enough to the phosphate anion of the amount avoiding calcium phosphate compound to precipitate in described ionogen.
The electro-chemical systems of 23. claims 22, wherein said ion-select electrode device comprises the entrance be communicated with described tank room fluid for being provided to by the phosphate anion of described amount in described tank room.
The electro-chemical systems of 24. claims 23, wherein said ion-select electrode device comprises at least one measuring apparatus of the concentration for measuring phosphate anion in described ionogen and/or calcium ion further.
The electro-chemical systems of 25. claims 24, wherein said ion-select electrode device comprises the controller being connected to described measuring apparatus and described entrance for controlling the input of phosphate anion in response to the reading from described measuring apparatus further.
The electro-chemical systems of 26. any one of claim 22-25, it is configured to for the manufacture of chlorizate.
The electro-chemical systems of 27. claims 26, wherein said chlorizate comprises sodium chlorate and/or clorox.
28. electrochemical process, comprising:
Anode and negative electrode are arranged in the ionogen comprising the impurity comprising calcium ion and iron ion;
Between described anode and described negative electrode, voltage is applied form the condition of electrolysate in described ionogen under; With
Phosphate anion is provided to measure as follows: described amount is enough to form protectiveness skin on the cathode with calcium ion at least partially in described ionogen; described protectiveness skin comprises calcium phosphate compound, and described amount is enough to substantially avoid iron phosphate compounds to precipitate in described ionogen.
The electrochemical process of 29. claims 28, wherein phosphate anion adds with the amount of the surf zone contacted with described ionogen based on described negative electrode.
The electrochemical process of 30. claims 28 or 29, is included in further before being immersed in described ionogen by described negative electrode on catalytic middle layer, applies described protectiveness skin.
The electrochemical process of 31. claims 30, wherein applies the outer field step of described protectiveness and comprises dash coat, dip-coating, sol-gel, electrochemical deposition, bionical coating, the isobaric coating of heat or plasma spraying.
The electrochemical process of 32. claims 28 or 29, is included in further after being immersed in described ionogen by described negative electrode on catalytic middle layer, forms described protectiveness skin.
The electrochemical process of 33. claims 32, wherein forms the outer field step of described protectiveness and comprises:
Phosphate anion is provided in described ionogen;
Ensure to there is enough calcium ions in described ionogen; With
The electrolytic condition being enough to cause the outer field formation of described protectiveness is provided.
The electrochemical process of 34. any one of claim 28-33, the outer field formation of wherein said protectiveness comprises:
Make Ca (OH) 2with H 3pO 4reaction is to produce Ca 3(PO 4) 2and water; With
Make Ca (OH) 2with Ca 3(PO 4) 2reaction is to produce Ca 10(PO 4) 6(OH) 2, wherein Ca 10(PO 4) 6(OH) 2form described protectiveness at least partially outer field.
The electrochemical process of 35. any one of claim 28-34, wherein provides phosphate anion with the phosphate concentration being up to about 75ppm in described ionogen.
The electrochemical process of 36. any one of claim 28-35, wherein phosphate concentration is about 50ppm for about 5ppm-.
The electrochemical process of 37. any one of claim 28-36, wherein phosphate concentration is low to being enough to prevent from forming iron phosphate compounds or settling on described anode.
The electrochemical process of 38. any one of claim 28-37, wherein phosphate concentration is low to being enough to prevent the O in described ionogen 2the rising of level.
The electrochemical process of 39. any one of claim 28-38, wherein phosphate concentration is low to being enough to the rising preventing voltage request.
The electrochemical process of 40. any one of claim 28-39, wherein phosphate anion is at least in part by H 3pO 4interpolation provided.
The electrochemical process of 41. any one of claim 28-40, wherein phosphate anion provided by the intrinsic existence in described ionogen at least in part.
The electrochemical process of 42. any one of claim 28-41, wherein calcium ion provided by the intrinsic existence in described ionogen at least in part.
The electrochemical process of 43. any one of claim 28-42, wherein said ionogen comprises for reacting first part's calcium ion to form calcium phosphate compound on the cathode with phosphate anion, and in described ionogen, keep unreacted second section calcium.
The electrochemical process of 44. any one of claim 28-43, wherein said technique is for the manufacture of chlorizate.
The electrochemical process of 45. claims 44, wherein said chlorizate comprises sodium chlorate and/or clorox.
The electrochemical process of 46. claims 44, wherein said chlorizate is sodium chlorate.
47. phosphate anions are in the purposes for manufacturing in the ionogen comprising calcium ion and iron ion in the electrochemical process of chlorizate, and wherein said phosphate anion is that to be enough to be formed on negative electrode with calcium ion at least partially the protectiveness comprising calcium phosphate compound outer and be enough to avoid the amount that iron phosphate compounds precipitates in described ionogen to provide.
The purposes of 48. claims 47, wherein said chlorizate comprises sodium chlorate and/or clorox.
49. electro-chemical systems, comprising:
For comprising electrolytical tank room, wherein said ionogen comprises calcium ion, iron ion and phosphate anion;
Be arranged in the anode of described tank room;
Be arranged in the negative electrode of described tank room; With
Ion-select electrode device; it is configured to regulate the ion concentration in described ionogen, described ionogen is comprised be enough to be formed on the cathode with calcium ion at least partially the protectiveness comprising calcium phosphate compound outer and be enough to the phosphate anion of the amount avoiding iron phosphate compounds to precipitate in described ionogen.
The electro-chemical systems of 50. claims 49, wherein said ion-select electrode device comprises the entrance be communicated with described tank room fluid for being provided to by the phosphate anion of described amount in described tank room.
The electro-chemical systems of 51. claims 50, wherein said ion-select electrode device comprises at least one measuring apparatus of the concentration for measuring phosphate anion, iron ion and/or calcium ion in described ionogen further.
The electro-chemical systems of 52. claims 51, wherein said ion-select electrode device comprises the controller being connected to described measuring apparatus and described entrance for controlling the input of phosphate anion in response to the reading from described measuring apparatus further.
53. electrochemical process, comprising:
Anode and negative electrode are arranged in the ionogen comprising the impurity comprising calcium ion, described negative electrode has the surf zone contacted with described ionogen;
Between described anode and described negative electrode, voltage is applied form the condition of electrolysate in described ionogen under; With
Phosphate anion is provided with the following predetermined amount of the described surf zone based on described negative electrode: described predetermined amount makes phosphate anion be consumed in the outer field formation of protectiveness of the surf zone contacted with described ionogen covering described negative electrode with calcium ion at least partially in described ionogen.
The electrochemical process of 54. claims 53, the phosphate anion of wherein said predetermined amount is about 0.025mg/cm 2negative electrode-Yue 0.2mg/cm 2negative electrode.
The electrochemical process of 55. claims 53, the phosphate anion of wherein said predetermined amount is about 0.05mg/cm 2negative electrode-Yue 0.15mg/cm 2negative electrode.
The electrochemical process of 56. any one of claim 53-55, wherein said ionogen comprises iron ion further, and phosphate anion is the amount interpolation avoiding iron phosphate compounds to precipitate in described ionogen further.
The electrochemical process of 57. any one of claim 53-56, wherein phosphate anion is that the amount avoiding extra calcium phosphate compound to precipitate in described ionogen is added further.
The electrochemical process of 58. any one of claim 53-57, is included in further before being immersed in described ionogen by described negative electrode on catalytic middle layer, applies described protectiveness skin.
The electrochemical process of 59. claims 58, wherein applies the outer field step of described protectiveness and comprises dash coat, dip-coating, sol-gel, electrochemical deposition, bionical coating, the isobaric coating of heat or plasma spraying.
The electrochemical process of 60. any one of claim 53-57, is included in further after being immersed in described ionogen by described negative electrode on catalytic middle layer, forms described protectiveness skin.
The electrochemical process of 61. claims 60, wherein forms the outer field step of described protectiveness and comprises:
Phosphate anion is provided in described ionogen;
Ensure to there is enough calcium ions in described ionogen; With
The electrolytic condition being enough to cause the outer field formation of described protectiveness is provided.
The electrochemical process of 62. any one of claim 53-61, the outer field formation of wherein said protectiveness comprises:
Make Ca (OH) 2with H 3pO 4reaction is to produce Ca 3(PO 4) 2and water; With
Make Ca (OH) 2with Ca 3(PO 4) 2reaction is to produce Ca 10(PO 4) 6(OH) 2, wherein Ca 10(PO 4) 6(OH) 2form described protectiveness at least partially outer field.
The electrochemical process of 63. any one of claim 53-62, wherein provides phosphate anion with the phosphate concentration being up to about 75ppm in described ionogen.
The electrochemical process of 64. any one of claim 53-63, wherein phosphate concentration is about 50ppm for about 5ppm-.
The electrochemical process of 65. any one of claim 53-64, wherein phosphate concentration is low to being enough to prevent the O in described ionogen 2the rising of level.
The electrochemical process of 66. any one of claim 53-65, wherein phosphate concentration is low to being enough to the rising preventing voltage request.
The electrochemical process of 67. any one of claim 53-66, wherein phosphate anion is at least in part by H 3pO 4interpolation provided.
The electrochemical process of 68. any one of claim 53-67, wherein phosphate anion provided by the intrinsic existence in described ionogen at least in part.
The electrochemical process of 69. any one of claim 53-68, wherein calcium ion provided by the intrinsic existence in described ionogen at least in part.
The electrochemical process of 70. any one of claim 53-69, wherein said ionogen comprises for reacting first part's calcium ion to form calcium phosphate compound on the cathode with phosphate anion, and in described ionogen, keep unreacted second section calcium.
The electrochemical process of 71. any one of claim 53-70, wherein said technique is for the manufacture of chlorizate.
The electrochemical process of 72. claims 71, wherein said chlorizate comprises sodium chlorate and/or clorox.
The electrochemical process of 73. claims 71, wherein said chlorizate is sodium chlorate.
The electrochemical process of 74. any one of claim 53-73, the phosphate anion of wherein said predetermined amount calculates based on the outer field target thickness of protectiveness to be obtained.
75. phosphate anions are in the purposes for manufacturing in the ionogen comprising calcium ion in the electrochemical process of chlorizate, and wherein phosphate anion provides with the following predetermined amount of the surf zone based on negative electrode: described predetermined amount makes phosphate anion be consumed in the outer field formation of protectiveness of the surf zone contacted with described ionogen covering described negative electrode with calcium ion at least partially.
The purposes of 76. claims 75, wherein said chlorizate comprises sodium chlorate and/or clorox.
77. electro-chemical systems, comprising:
For comprising electrolytical tank room, wherein said ionogen comprises calcium ion and phosphate anion;
Be arranged in the anode of described tank room;
Be arranged in the negative electrode of described tank room; With
Ion-select electrode device; it is configured to regulate the ion concentration in described ionogen, makes described ionogen comprise the phosphate radical of the following predetermined amount of the surf zone based on described negative electrode: described predetermined amount makes phosphate anion be consumed in the outer field formation of protectiveness of the surf zone contacted with described ionogen covering described negative electrode with calcium ion at least partially.
The electro-chemical systems of 78. claims 77, wherein said ion-select electrode device comprises the entrance be communicated with described tank room fluid for being provided to by the phosphate anion of described amount in described tank room.
The electro-chemical systems of 79. claims 78, wherein said ion-select electrode device comprises at least one measuring apparatus of the concentration for measuring phosphate anion in described ionogen and/or calcium ion further.
The electro-chemical systems of 80. claims 79, wherein said ion-select electrode device comprises the controller being connected to described measuring apparatus and described entrance for controlling the input of phosphate anion in response to the reading from described measuring apparatus further.
81. prefabricated negative electrodes, comprising:
Substrate;
Catalytic middle layer; With
The protectiveness comprising calcium phosphate compound is outer.
The prefabricated negative electrode of 82. claims 81, wherein said substrate comprises stainless steel.
The prefabricated negative electrode of 83. claims 82, wherein said stainless steel is 400 series stainless steels.
The prefabricated negative electrode of 84. any one of claim 81-83, wherein said substrate comprise have be enough to prevent electrolyzer close down the phase during iron ion enter the material of electrolytical erosion resistance.
The prefabricated negative electrode of 85. any one of claim 81-84, wherein said catalytic middle layer adjoins with the outside surface of described substrate.
The prefabricated negative electrode of 86. any one of claim 81-85, wherein said catalytic middle layer comprises the metallic matrix doped with catalytic compound.
The prefabricated negative electrode of 87. claims 86, wherein said metallic matrix is iron aluminide.
The prefabricated negative electrode of 88. claims 86 or 87, wherein said catalytic compound comprises Ru.
The prefabricated negative electrode of 89. any one of claim 81-88, wherein said calcium phosphate compound comprises hydroxyl calcium phosphate compound.
The prefabricated negative electrode of 90. any one of claim 81-89, wherein said protectiveness skin comprises hydroxyapatite.
The prefabricated negative electrode of 91. any one of claim 81-90, wherein said protectiveness skin is made up of hydroxyapatite substantially.
The prefabricated negative electrode of 92. any one of claim 81-91, wherein said protectiveness skin has the thickness of about 0.25 micron of-Yue 1.5 microns.
The prefabricated negative electrode of 93. any one of claim 81-91, wherein said protectiveness skin has the thickness of about 0.5 micron of-Yue 1 micron.
The prefabricated negative electrode of 94. any one of claim 81-93, the whole outside surface that wherein said protectiveness skin covers described catalytic middle layer directly contacts with the calcium impurities in described ionogen to prevent described catalytic middle layer.
The prefabricated negative electrode of 95. any one of claim 81-94, wherein said protectiveness skin is that dash coat, dip-coating, sol-gel applying, electrochemical deposition, bionical coating, the isobaric coating of heat or plasma spraying are on described catalytic middle layer.
The prefabricated negative electrode of 96. any one of claim 81-95, wherein said protectiveness skin has network structure.
The prefabricated negative electrode of 97. any one of claim 81-96, wherein said protectiveness skin has honeycomb structure.
The prefabricated negative electrode of 98. any one of claim 81-97, wherein said protectiveness skin has evolving hydrogen reaction lower can be occurred at it, prevent calcium impurities from poisoning the structure of described intermediate catalyst layer simultaneously.
The prefabricated negative electrode of 99. any one of claim 81-98, wherein said protectiveness skin has and makes it possible to stop chlorate anions and hypochlorite ion to arrive the surface of described intermediate catalyst layer to reduce or to avoid the structure of following reaction:
ClO -+ H 2o+2e -=>Cl -+ 2OH -; And/or
ClO 3 -+3H 2O+6e -＝>Cl -+6OH -。
100. if the prefabricated negative electrode that limits in any one of claim 81-98 is for the manufacture of the purposes in the electrolyzer of chlorizate.
The purposes of 101. claims 100, wherein said chlorizate comprises sodium chlorate and/or clorox.
102. electrochemical process, comprising:
Anode and the prefabricated negative electrode as limited in any one of claim 81-98 are arranged in the ionogen comprising the impurity comprising calcium ion;
Between described anode and described prefabricated negative electrode, voltage is applied form the condition of electrolysate in described ionogen under.
The technique of 103. claims 102, comprises one or more features of claim 1-19, any one of 28-46 and 53-74.
104. for the manufacture of the method for the prefabricated negative electrode be used in the manufacture of chlorizate, and described method comprises:
Substrate is provided;
The top of described substrate provides catalytic middle layer; With
Be applied on described catalytic middle layer by protectiveness skin, wherein protectiveness skin comprises calcium phosphate compound.
The method of 105. claims 104, wherein said prefabricated negative electrode is as limited in any one of claim 81-98.
The method of 106. claims 104 or 105, wherein applies the outer field step of described protectiveness and comprises dash coat.
The method of 107. claims 104 or 105, wherein applies the outer field step of described protectiveness and comprises dip-coating.
The method of 108. claims 104 or 105, wherein applies the outer field step of described protectiveness and comprises sol-gel process.
The method of 109. claims 104 or 105, wherein applies the outer field step of described protectiveness and comprises electrochemical deposition.
The method of 110. claims 104 or 105, wherein applies the outer field step of described protectiveness and comprises bionical coating method.
The method of 111. claims 104 or 105, wherein applies the outer field step of described protectiveness and comprises the isobaric coating of heat.
The method of 112. claims 104 or 105, wherein applies the outer field step of described protectiveness and comprises plasma spraying.
113. electrochemical process, comprising:
Anode and negative electrode are arranged in the ionogen comprising the impurity comprising calcium ion, wherein said negative electrode comprises:
The substrate be made up of corrosion resistant material; With
Catalytic middle layer;
For the electrolysis phase, carry out electrolysis, it applies voltage under being included in the condition forming electrolysate in described ionogen between described anode and described negative electrode;
Periodically described electrolysis closed down for the phase of closing down, it comprises and stops described voltage, the described corrosion resistant material of wherein said substrate prevent described close down each of phase during iron ion be discharged in described ionogen; With
Phosphate anion is provided to measure as follows: described amount enough makes during each electrolysis phase in described ionogen; it is outer that phosphate anion and at least partially calcium ion form or again formed protectiveness on the catalytic middle layer of described negative electrode, and described protectiveness skin comprises calcium phosphate compound.
The technique of 114. claims 113, comprises one or more features of claim 1-19,28-46,53-74,102 and 103 any one.
CN201380073663.XA 2013-02-22 2013-02-22 Techniques for production of chlorated products and prefabricated cathode structures Pending CN105074056A (en)

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Application publication date: 20151118