EP0245279B1 - Procede d'oxydation electrochimique de solutions de chrome iii dans l'acide sulfurique en solutions de chrome vi - Google Patents

Procede d'oxydation electrochimique de solutions de chrome iii dans l'acide sulfurique en solutions de chrome vi Download PDF

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Publication number
EP0245279B1
EP0245279B1 EP86901730A EP86901730A EP0245279B1 EP 0245279 B1 EP0245279 B1 EP 0245279B1 EP 86901730 A EP86901730 A EP 86901730A EP 86901730 A EP86901730 A EP 86901730A EP 0245279 B1 EP0245279 B1 EP 0245279B1
Authority
EP
European Patent Office
Prior art keywords
chromium
nitric acid
solutions
litre
sulphuric acid
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.)
Expired
Application number
EP86901730A
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German (de)
English (en)
Other versions
EP0245279A1 (fr
Inventor
Richard Vytlacil
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.)
Andritz Hydro GmbH Austria
Original Assignee
Andritz Hydro GmbH Austria
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Andritz Hydro GmbH Austria filed Critical Andritz Hydro GmbH Austria
Publication of EP0245279A1 publication Critical patent/EP0245279A1/fr
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Publication of EP0245279B1 publication Critical patent/EP0245279B1/fr
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Classifications

    • 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

Definitions

  • the invention relates to a process for the electrochemical oxidation of sulfuric acid chromium III solutions to chromium VI solutions, in a cell divided by means of a diaphragm, while flushing air into the electrolyte in the cathode compartment.
  • nitric acid-containing, sulfuric acid chromium III solutions such as those that occur in the oxidative purification of flue gases
  • nitric acid remains in the electrolyte during the processing of the oxidizing agent, up to 30% ammonium ions are formed on the cathode in the presence of chromium III ions, in addition to the hydrogen.
  • the discharge of these ammonium salts is only possible by complex processes.
  • the cell voltages that can be achieved in practice in this arrangement lie between 4.8 and 6.4 volts and can be increased even further due to the poorer conductivity of chrome-plated cathodes.
  • the object of the invention is to provide a method of the type mentioned at the outset which on the one hand avoids the disadvantages of the known methods and in which on the other hand the electricity costs for the electrolysis are lower.
  • the process according to the invention is characterized in that the electrolyte contains nitric acid, sulfuric acid and chromium III and the nitric acid is used as a redox carrier for the oxygen electrode serving as the cathode and that the nitric acid is regenerated by flushing in oxygen or air.
  • the method according to the invention allows a considerable reduction in the electricity costs during electrolysis.
  • the most positive cathode fraction is the cathodic oxygen reduction.
  • the reduction of oxygen in acidic solutions is, however, kinetically strongly inhibited.
  • Usable oxygen electrodes require either expensive catalysts based on precious metals or suitable redox carriers in an acidic environment.
  • the reduced species of the redox transmitter must have such a high reactivity that it can be oxidized again by the oxygen dissolved in the electrolyte.
  • the reduction of nitric acid was chosen as the cathode reaction for the process according to the invention, since its reversible potential of +940 mV is close to that of the oxygen electrode.
  • the cell voltages that can be achieved under these conditions are between 0.9 volts and approximately 2 volts. This means that the electricity costs for electrolysis can be reduced to about 1/3.
  • the electrolysis is preferably operated with an electrolyte composition of 20 g / l to 300 g / IH 2 SO 4 , 20 g / l to 200 g / l HN0 3 and 20 g / l to 30 g / l chromium .
  • activated carbon and / or graphite are preferably used as the cathode material.
  • electrodes with high oxygen overvoltage such as, for. B. lead dioxide, manganese dioxide, tin dioxide and / or combinations thereof.
  • the electrolytic cell consists of the usual arrangement of several anode and cathode spaces, which are separated by diaphragms and are connected in series, anodes and cathodes working as bipolar electrodes.
  • the electrolyte is supplied to the individual cathode compartments and then to the anode compartments via appropriate supply lines and is drawn off via a collecting line. Air and / or oxygen is blown in, for example, through perforated tubes which are arranged in the bottom of the cathode compartments.
  • Either porous gas diffusion electrodes made of activated carbon or graphite or shaking electrodes made of the same material are used as cathodes. This consumes residual gas, with traces of nitrogen oxides, which can arise as intermediates in the cathode reaction and are carried away with the gas flow, is returned to the oxidative flue gas scrubber.

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  • Chemical & Material Sciences (AREA)
  • Inorganic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Electrolytic Production Of Non-Metals, Compounds, Apparatuses Therefor (AREA)
  • Treating Waste Gases (AREA)
  • Water Treatment By Electricity Or Magnetism (AREA)

Abstract

Le traitement de solutions de chrome III dans l'acide sulfurique contenant de l'acide nitrique, comme elles se produisent lors de la purification oxydante des gaz de combustion, présente de grosses difficultés ou est très coûteux. Le but de l'invention est de créer un procédé dans lequel les frais de courant pour l'électrolyse sont faibles. Le procédé selon l'invention pour l'oxydation électrochimique de solutions de chrome III dans l'acide sulfurique en solutions de chrome VI réside, pour l'essentiel, en ce que l'acide nitrique, l'acide sulfurique et le chrome sont contenus dans l'électrolyte, l'acide nitrique étant utilisé comme transporteur rédox pour l'électrode d'oxygène servant de cathode et l'acide nitrique étant régénéré par l'oxygène. Le carbone ou le graphite sont utilisés comme matière de la cathode. Pour l'anode, on utilise des électrodes présentant une surtension d'oxygène élevée comme, par exemple, le dioxyde de plomb. Les tensions de la cellule que l'on peut obtenir dans ces conditions sont comprises entre 0,9 et 2 volts. Cela signifie que les dépenses de courant pour l'électrolyse sont abaissées d'environ 1/3.

Claims (4)

1. Procédé d'oxydation électrochimique de solutions sulfuriques de chrome III en solutions de chrome VI, caractérisé par le fait que dans l'électrolyte sont contenus de l'acide nitrique, de l'acide sulfurique et du chrome, l'acide nitrique étant utilisé comme agent de transfert redox pour l'électrode à oxygène servant de cathode, et qu'on régénère l'acide nitrique par balayage d'oxygène ou d'air dans les électrolytes se trouvant dans le compartiment cathodique.
2. Procédé selon la revendication 1, caractérisé par le fait que l'électrolyse est conduite, de préférence, avec une composition de l'électrolyte de 20 g/I à 300 g/I de H2SO4, 20 g/I à 200 g/I de HN03, et 20 g/I à 30 g/I de chrome.
3. Procédé selon l'une des revendications 1 ou 2, caractérisé par le fait qu'on utilise, comme matériau de cathode, de préférence, du charbon actif et/ou du graphite.
4. Procédé selon l'une des revendications 1 à 3, caractérisé par le fait qu'on utilise, comme matériau d'anode, des électrodes présentant une surtension d'oxygène élevée, comme, par exemple, le dioxyde de plomb, le dioxyde de manganèse, le dioxyde d'étain et/ou leurs combinaisons.
EP86901730A 1985-02-27 1986-02-27 Procede d'oxydation electrochimique de solutions de chrome iii dans l'acide sulfurique en solutions de chrome vi Expired EP0245279B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
AT577/85 1985-02-27
AT0057785A AT382894B (de) 1985-02-27 1985-02-27 Verfahren zur elektrochemischen oxidation von schwefelsauren chrom-iii-loesungen zu chrom-vil¯sungen

Publications (2)

Publication Number Publication Date
EP0245279A1 EP0245279A1 (fr) 1987-11-19
EP0245279B1 true EP0245279B1 (fr) 1989-07-12

Family

ID=3494262

Family Applications (1)

Application Number Title Priority Date Filing Date
EP86901730A Expired EP0245279B1 (fr) 1985-02-27 1986-02-27 Procede d'oxydation electrochimique de solutions de chrome iii dans l'acide sulfurique en solutions de chrome vi

Country Status (11)

Country Link
US (1) US4859294A (fr)
EP (1) EP0245279B1 (fr)
JP (1) JPS62501979A (fr)
AT (1) AT382894B (fr)
AU (1) AU5580786A (fr)
BG (1) BG80794A (fr)
DD (1) DD243300A5 (fr)
DE (1) DE3664341D1 (fr)
FI (1) FI80075C (fr)
HU (1) HU201361B (fr)
WO (1) WO1986005215A1 (fr)

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3940978A1 (de) * 1989-12-12 1991-06-13 Hoechst Ag Verfahren zur elektrochemischen regenerierung von chromschwefelsaeure
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
JP6206382B2 (ja) * 2014-11-28 2017-10-04 住友金属鉱山株式会社 水酸化インジウム粉の製造方法
US20230151498A1 (en) * 2017-09-08 2023-05-18 Haskoli Islands Metal oxide catalysts and methods for producing ammonia

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE103860C (fr) *
US1739107A (en) * 1925-11-05 1929-12-10 Marvin J Udy Process of making chromic acid
DE2310622A1 (de) * 1973-03-02 1974-09-12 Basf Ag Diaphragmenzelle fuer die herstellung von schwefelsauren chromsaeureloesungen
US4006067A (en) * 1973-03-05 1977-02-01 Gussack Mark C Oxidation-reduction process
US4273628A (en) * 1979-05-29 1981-06-16 Diamond Shamrock Corp. Production of chromic acid using two-compartment and three-compartment cells

Also Published As

Publication number Publication date
US4859294A (en) 1989-08-22
ATA57785A (de) 1986-09-15
HU201361B (en) 1990-10-28
JPS62501979A (ja) 1987-08-06
HUT46081A (en) 1988-09-28
BG80794A (bg) 1993-12-24
WO1986005215A1 (fr) 1986-09-12
FI873678A0 (fi) 1987-08-25
DE3664341D1 (en) 1989-08-17
AT382894B (de) 1987-04-27
FI873678A (fi) 1987-08-25
AU5580786A (en) 1986-09-24
DD243300A5 (de) 1987-02-25
FI80075C (fi) 1990-04-10
FI80075B (fi) 1989-12-29
EP0245279A1 (fr) 1987-11-19

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