EP0436146A1 - Procédé de régénération électrochimique d'acide chromosulfurique - Google Patents

Procédé de régénération électrochimique d'acide chromosulfurique Download PDF

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Publication number
EP0436146A1
EP0436146A1 EP90123633A EP90123633A EP0436146A1 EP 0436146 A1 EP0436146 A1 EP 0436146A1 EP 90123633 A EP90123633 A EP 90123633A EP 90123633 A EP90123633 A EP 90123633A EP 0436146 A1 EP0436146 A1 EP 0436146A1
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EP
European Patent Office
Prior art keywords
anode
cathode
tub
trough
cell
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP90123633A
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German (de)
English (en)
Other versions
EP0436146B1 (fr
Inventor
Hans Dr. Herbst
Jürgen Dr. Stenzel
Siegfried Dr. Benninger
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Hoechst AG
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Hoechst AG
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Filing date
Publication date
Application filed by Hoechst AG filed Critical Hoechst AG
Publication of EP0436146A1 publication Critical patent/EP0436146A1/fr
Application granted granted Critical
Publication of EP0436146B1 publication Critical patent/EP0436146B1/fr
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B1/00—Electrolytic production of inorganic compounds or non-metals
    • 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
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D21/00—Processes for servicing or operating cells for electrolytic coating
    • C25D21/16—Regeneration of process solutions
    • C25D21/18—Regeneration of process solutions of electrolytes

Definitions

  • the invention relates to a method for the electrochemical regeneration of chromosulfuric acid, in which a novel electrolysis cell is used.
  • electrodes made of lead or lead alloys and electrolytic cells with lead walls, for example steel troughs lined with lead, are usually used.
  • a membrane cell for chlor-alkali electrolysis which consists of two half-shells, one half-shell made of titanium sheet and the other made of stainless steel or nickel sheet (see Bergner and Hannesen, GDCH Annual Conference on Angew. Electrochemistry, October 1984).
  • the electrodes each consist of a blind sheet which is activated and inserted into the Half shell is welded.
  • the electrodes are connected to the rear walls of the half-shells at regular intervals using corrugated strips.
  • the two half-shells of a cell are separated from each other by a permeable membrane and seals.
  • the task was to find a process in which the chromosulfuric acid is regenerated in a closed cell system and the resulting hydrogen can be obtained.
  • the invention thus relates to a process for the electrochemical regeneration of chromosulphuric acid by anodic oxidation of Cr3+ ions to Cr6+ ions, the anolyte 20 to 200 g / dm3 total CrO3 and 100 to 600 g / dm3 H2SO4 and the catholyte 50 to Contains 500 g / dm3 H2SO4, characterized in that the regeneration is carried out in an electrolysis cell, which consists of two trough-like metal half-shells, the open sides of which face each other, with a plate or plate provided with holes or slits in the anode trough the anode tub is connected by corrugated strips, is located as the anode, there is a sheet in the cathode tub, which is connected to the cathode tub by corrugated tapes, is located as the cathode, the anode tub and cathode tub are separated from one another by a current-permeable, hydraulically sealing partition
  • FIG. 1 shows an overall perspective view of an electrolysis cell
  • FIG. 2 shows a section along the line II-II in FIGS. 1, 3 and 4
  • FIG. 3 shows a section along the line III-III in FIGS. 1, 2 and 4
  • FIG. 4 shows a plan view in the direction of arrow IV in FIGS. 1, 2 and 3.
  • the cell consists of two trough-like metal half-shells (1) and (2).
  • a perforated or slotted plate (3) perforated plate, expanded metal, or the like
  • the plate (3) serves as an anode.
  • a sheet (5) as the cathode, which is connected to the trough (2) via corrugated strips (6).
  • the cathode consists of a simple sheet metal, sheet metal strips, perforated sheet metal, expanded metal or a sheet metal blind, preferably a sheet metal sheet.
  • Anode tub (1) and cathode tub (2) are separated from each other by a current-permeable, hydraulically sealing partition (7) and seals (8) and (9). They are held together by two insulated steel frames (10) and (11). The screws (16) are insulated by means of plastic bushings (17) and plastic washers (18). There is an inlet pipe (12) for the anolyte on the underside of the anode tub (1), and an inlet pipe (14) for the catholyte on the cathode tub (2). The exhaust pipes (13) and (15) are located on the top of the trays (1) and (2).
  • Figure 2 also shows the position of the corrugated strips (4) and (6) and the offset attachment of the inlet pipes (12) and (14).
  • the circumferential steel frame (11) can finally be seen from FIGS. 3 and 4.
  • the anode tub (1) and the corrugated strips (4) consist of titanium, while the cathode tray (2) and the corrugated strips (6) consist of nickel or a nickel alloy, for example ®Hastelloy.
  • valve metals titanium, tantalum, vanadium and zirconium already used in chlor-alkali electrolysis are also suitable as materials for the anode (3) under the aggressive conditions of chromic acid electrolysis. Under anodic current load, these metals form a coherent oxide film on their surface, which protects the base material. If the surface of the anodes is not activated, the oxide layer formed prevents further current flow. Suitable activation layers for these metals for the chromic acid electrolysis are only electron-conducting oxides which have a high overvoltage in relation to oxygen, for example lead dioxide, manganese dioxide, tin dioxide, tantalum oxides or iridium oxides.
  • One of the highest surge voltages for oxygen is characterized by lead dioxide, which is preferred. This results in the anodic electrochemical reaction on a titanium anode coated with PbO2 at current densities of 200 A / m2 to 2500 A / m2 current yields between 96% and 88%.
  • Nickel and nickel alloys are suitable as materials for the cathode (5).
  • sulfuric acid as the catholyte
  • the reaction equation Discharges protons at the cathode and develops hydrogen, which leaves the cathode space in gaseous form.
  • nickel is only resistant to 10 to 35% sulfuric acid if it is cathodically polarized. It must therefore be prevented that the nickel cathodes are exposed to sulfuric acid when de-energized.
  • the hydrogen overvoltage on nickel is relatively low at 0.42 V at a current density of 100 A / m2, compared to quite high on lead under the same conditions at 1.09 v.
  • the consequence of this is that when nickel is used as the cathode, a correspondingly lower cell voltage results.
  • cation-active ion exchange membranes made of perfluorinated polymers with sulfonyl groups have proven their worth. They show excellent durability and selectivity in the electrolytes used up to temperatures of 110 ° C. The use of such membranes makes it possible to collect the cathodically developed hydrogen separately and to use it further.
  • the electrolytic cell to be used and assembled according to the invention can be operated after filling catholyte into the cathode compartment and anolyte into the anode compartment and after pressing the power supply lines of a rectifier onto the anode tub and cathode tub rear wall.
  • the continuous supply of catholyte and anolyte from storage tanks takes place via pumps at the lower end of the electrode space.
  • the electrolyte leaves the cell.
  • the anolyte with the desired composition is passed on for further use, the catholyte is continuously circulated through a buffer container and is concentrated again from time to time.
  • the undesirable, to a small extent, developing oxygen (due to water decomposition) at the anode ensures sufficient mixing of the anolyte and supports the diffusion of Cr3+ to the anode surface.
  • This effect can be intensified by additionally blowing inert gas into the anode compartment.
  • This electrolysis cell is preferably not operated individually. Rather, multiple cells are pressed together in a cell frame by means of a pressing device rear wall to rear wall. This means that the current introduced at the beginning of the cell package with copper bars can flow through all cells and is derived from copper bars at the end of the package. Special contact strips ensure good current transfer between the cells. If the cells are operated in this way, a bipolar cell is present. All individual elements are connected in series.
  • the concentration in the anolyte is 20 to 200, preferably 100 to 200, in particular 130 to 170 g / dm3 total CrO3 and 100 to 600, preferably 300 to 600, in particular 450 to 550 g / cm3 H2SO4.
  • the catholyte contains 50 to 500, preferably 300 to 350 g / dm3 H2SO4.
  • the electrolysis is carried out at a temperature of 40 to 110, preferably 80 to 110 ° C. and a current density of 100 to 2500, preferably 500 to 2500 A / m2.
  • the electrolysis was carried out in a round laboratory membrane cell, which was composed of 2 glass dishes and was flange-sealed with two PTFE O-rings.
  • the two glass bowls formed the cathode and anode space. They were separated by a polymer membrane made of a perfluorinated polymer, which was clamped between the two O-rings.
  • the two circular electrodes were held eccentrically, the DC supply was via these holders.
  • the spacing of the anode and cathode could be changed in relation to each other and to the membrane.
  • Anolyte and catholyte were heated in the two cell halves with heating rods to 90 ° C and kept constant at this temperature during the electrolysis.
  • the cathode consisted of non-activated nickel expanded metal, the anode made of titanium expanded metal, which was coated on all sides with electrodeposited PbO2.
  • the cathode-anode distance was 8 mm.
  • the catholyte was circulated through the cathode compartment with a constant throughput of 9 cm3 / h at all current densities.
  • the electrolysis data obtained are shown in Table 1.
  • a titanium expanded metal anode activated with a tantalum oxide / iridium oxide mixture was tested for suitability in a second glass cell, the structure of which corresponded completely to the cell described above.

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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)
  • Electrolytic Production Of Non-Metals, Compounds, Apparatuses Therefor (AREA)
  • Electrodes For Compound Or Non-Metal Manufacture (AREA)
  • Electrolytic Production Of Metals (AREA)
  • Inorganic Compounds Of Heavy Metals (AREA)
EP90123633A 1989-12-12 1990-12-08 Procédé de régénération électrochimique d'acide chromosulfurique Expired - Lifetime EP0436146B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3940978 1989-12-12
DE3940978A DE3940978A1 (de) 1989-12-12 1989-12-12 Verfahren zur elektrochemischen regenerierung von chromschwefelsaeure

Publications (2)

Publication Number Publication Date
EP0436146A1 true EP0436146A1 (fr) 1991-07-10
EP0436146B1 EP0436146B1 (fr) 1994-04-20

Family

ID=6395298

Family Applications (1)

Application Number Title Priority Date Filing Date
EP90123633A Expired - Lifetime EP0436146B1 (fr) 1989-12-12 1990-12-08 Procédé de régénération électrochimique d'acide chromosulfurique

Country Status (8)

Country Link
US (1) US5045162A (fr)
EP (1) EP0436146B1 (fr)
JP (1) JPH05238736A (fr)
DE (2) DE3940978A1 (fr)
DK (1) DK0436146T3 (fr)
ES (1) ES2054203T3 (fr)
IE (1) IE65467B1 (fr)
PT (1) PT96157A (fr)

Families Citing this family (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4315411C2 (de) * 1993-05-10 1995-04-27 Lpw Anlagen Gmbh Verfahren zur Regenerierung von verbrauchten Chromsäurelösungen
DE4419683C2 (de) * 1994-06-06 2000-05-04 Eilenburger Elektrolyse & Umwelttechnik Gmbh Bipolare Filterpressenzelle für anodische Oxidationen an Platin
DE19519177C2 (de) * 1995-05-24 1999-05-12 Warnecke Hans Joachim Prof Dr Verfahren und Vorrichtung zur Abfall-CSB-Wert-Verminderung
AT409764B (de) * 1998-03-06 2002-11-25 Treibacher Ind Ag Verfahren zur oxidation von vanadium
NZ331053A (en) * 1998-07-21 2002-12-20 Osmose New Zealand Process for electrochemical generation of higher oxidate state values from lower oxidation state values above zero of transition metal(s) [eg;
FR2791662B1 (fr) * 1999-04-01 2001-06-22 Conservatoire Nat Arts Procede de traitement electrochimique d'effluents, notamment d'effluents de tannerie, comprenant des sels de chrome
US6468414B1 (en) 2001-02-16 2002-10-22 Hydro-Quebec Method of purification of a redox mediator before electrolytic regeneration thereof
GB2399349A (en) * 2003-03-13 2004-09-15 Kurion Technologies Ltd Regeneration of chromic acid etching and pickling baths
JP3836833B2 (ja) * 2003-11-11 2006-10-25 山口 嘉春 水素と酸素の混合ガス発生装置およびその電解槽
DE102004023161A1 (de) * 2004-05-07 2005-11-24 Eilenburger Elektrolyse- Und Umwelttechnik Gmbh Elektrolysezelle mit Mehrlagen-Streckmetall-Kathoden
CN108103521B (zh) * 2017-12-22 2019-10-15 四川省银河化学股份有限公司 一种提高电解法制备铬酸酐品质的方法
WO2024234026A1 (fr) * 2023-05-17 2024-11-21 Andritz Ag Cellule électrolytique, bloc électrolytique comprenant plusieurs cellules électrolytiques correspondantes et dispositif électrolytique doté de plusieurs cellules électrolytiques correspondantes
AT527859A1 (de) * 2023-12-20 2025-07-15 Andritz Ag Maschf Elektrolyseur zur alkalischen Wasserstoffelektrolyse

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2219806A1 (en) * 1973-03-02 1974-09-27 Basf Ag Diaphragm cell for chromic-sulphuric acid prodn. - with membrane near cathode and high anode-cathode surface ratio
US4006067A (en) * 1973-03-05 1977-02-01 Gussack Mark C Oxidation-reduction process
FR2354399A1 (fr) * 1976-06-11 1978-01-06 Sarel Compartiment cathodique pour la regeneration electrolytique de solutions sulfo-chromiques et/ou phospho-chromiques
EP0189535A1 (fr) * 1985-01-16 1986-08-06 Uhde GmbH Appareil d'électrolyse
WO1986005215A1 (fr) * 1985-02-27 1986-09-12 Elin-Union Aktiengesellschaft Für Elektrische Indu Procede d'oxydation electrochimique de solutions de chrome iii dans l'acide sulfurique en solutions de chrome vi

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3761369A (en) * 1971-10-18 1973-09-25 Electrodies Inc Process for the electrolytic reclamation of spent etching fluids

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2219806A1 (en) * 1973-03-02 1974-09-27 Basf Ag Diaphragm cell for chromic-sulphuric acid prodn. - with membrane near cathode and high anode-cathode surface ratio
US4006067A (en) * 1973-03-05 1977-02-01 Gussack Mark C Oxidation-reduction process
FR2354399A1 (fr) * 1976-06-11 1978-01-06 Sarel Compartiment cathodique pour la regeneration electrolytique de solutions sulfo-chromiques et/ou phospho-chromiques
EP0189535A1 (fr) * 1985-01-16 1986-08-06 Uhde GmbH Appareil d'électrolyse
WO1986005215A1 (fr) * 1985-02-27 1986-09-12 Elin-Union Aktiengesellschaft Für Elektrische Indu Procede d'oxydation electrochimique de solutions de chrome iii dans l'acide sulfurique en solutions de chrome vi

Also Published As

Publication number Publication date
IE904464A1 (en) 1991-06-19
JPH05238736A (ja) 1993-09-17
US5045162A (en) 1991-09-03
PT96157A (pt) 1991-09-30
EP0436146B1 (fr) 1994-04-20
DE59005450D1 (de) 1994-05-26
IE65467B1 (en) 1995-11-01
DE3940978A1 (de) 1991-06-13
ES2054203T3 (es) 1994-08-01
DK0436146T3 (da) 1994-08-08

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