EP0356806B1 - Procédé de production d'acide chromique - Google Patents
Procédé de production d'acide chromique Download PDFInfo
- Publication number
- EP0356806B1 EP0356806B1 EP89115034A EP89115034A EP0356806B1 EP 0356806 B1 EP0356806 B1 EP 0356806B1 EP 89115034 A EP89115034 A EP 89115034A EP 89115034 A EP89115034 A EP 89115034A EP 0356806 B1 EP0356806 B1 EP 0356806B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- chromic acid
- electrolysis
- dichromate
- solution
- membrane
- 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 - Lifetime
Links
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
- C25B1/01—Products
- C25B1/22—Inorganic acids
Definitions
- the invention relates to a process for the production of chromic acid by electrolysis of dichromate and / or monochromate solutions in electrolysis cells, the anode and cathode spaces of which are separated by cation exchange membranes.
- the electrolytic production of chromic acid takes place in an electrolytic cell, the electrode spaces of which are separated by a cation exchange membrane.
- a solution of alkali dichromate - usually sodium dichromate -, alkali monochromate or a mixture of alkali dichromate with alkali monochromate is introduced into the anode compartment and converted into a solution containing chromic acid by selectively transferring alkali ions through the membrane into the cathode compartment.
- alkali dichromate usually sodium dichromate -, alkali monochromate or a mixture of alkali dichromate with alkali monochromate
- the electrolysis is operated so that constant ratios of chromic acid to alkali ions are established in continuous operation.
- the solutions formed in the anode compartment of the cell are concentrated, it being possible for the crystallization to take place, for example, at 60 to 100.degree.
- the crystallized chromic acid is separated off, washed and dried.
- the object of the invention was to provide a process for the production of chromic acid by electrolysis which does not have the disadvantages described.
- the invention relates to a process for the production of chromic acid by electrolysis of dichromate and / or monochromate solutions in electrolysis cells, the anode and cathode spaces of which are separated by a cation exchange membrane, which is characterized in that the chromic acid content of the solution in the anode space increases periodically compared to a continuous operating state becomes.
- This increase is preferably carried out by lowering the throughput of the dichromate and / or monochromate solution through the anode compartment of the cell.
- the process according to the invention is preferably operated so that the periodic increase in the chromic acid concentration is carried out after an electrolysis time of 1 to 100 days.
- the choice of the time of this measure depends on the content of polyvalent cations in the dichromate and / or monochromate solution. If these cations are very low, the measure can also be carried out after more than 100 days.
- the electrolytic cells used in the examples consisted of anode compartments made of pure titanium and cathode compartments made of stainless steel. Cation exchange membranes from Du Pont with the designation Nafion® 324 were used as membranes.
- the cathodes were made of stainless steel and the anodes were made of expanded titanium with an electrocatalytically active layer of tantalum oxide and iridium oxide. Such anodes are described, for example, in US Pat. No. 3,878,083.
- the distance between the electrodes and the membrane was 1.5 mm in all cases.
- Sodium dichromate solutions with a content of 800 g / l Na2Cr2O7 ⁇ 2 H2O and with the levels of impurities listed in the individual examples were introduced into the anode compartments.
- the electrolysis temperature was 80 ° C. in all cases and the current density was 3 kA / m2 of the projected area of the anode and cathode facing the membrane, this area being 11.4 cm ⁇ 6.7 cm.
- these solutions were converted into solutions containing chromic acid, the rate of introduction of the sodium dichromate solutions being chosen such that molar ratios of sodium ions to chromium (VI) of 0.8 and 0.4 were established in the anolytes.
- the electrolysis cells were operated in such a way that molar ratios of sodium ions to chromium (VI) of 0.8 and in each case 3 days of 0.4 were obtained in the anolyte.
- the membrane had and was like the membrane of Example 1 interspersed with white inclusions.
- the life of the membrane was considerably extended under the selected conditions with high calcium contents in the electrolyte.
Landscapes
- 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)
- Inorganic Compounds Of Heavy Metals (AREA)
Claims (4)
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE3829125A DE3829125A1 (de) | 1988-08-27 | 1988-08-27 | Verfahren zur herstellung von chromsaeure |
DE3829125 | 1988-08-27 |
Publications (3)
Publication Number | Publication Date |
---|---|
EP0356806A2 EP0356806A2 (fr) | 1990-03-07 |
EP0356806A3 EP0356806A3 (en) | 1990-04-18 |
EP0356806B1 true EP0356806B1 (fr) | 1992-06-24 |
Family
ID=6361724
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP89115034A Expired - Lifetime EP0356806B1 (fr) | 1988-08-27 | 1989-08-15 | Procédé de production d'acide chromique |
Country Status (10)
Country | Link |
---|---|
US (1) | US5071522A (fr) |
EP (1) | EP0356806B1 (fr) |
JP (1) | JP2839154B2 (fr) |
AR (1) | AR244351A1 (fr) |
BR (1) | BR8904279A (fr) |
CA (1) | CA1337808C (fr) |
DE (2) | DE3829125A1 (fr) |
ES (1) | ES2032636T3 (fr) |
MX (1) | MX171486B (fr) |
TR (1) | TR24639A (fr) |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6063252A (en) * | 1997-08-08 | 2000-05-16 | Raymond; John L. | Method and apparatus for enriching the chromium in a chromium plating bath |
Family Cites Families (13)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CA739447A (en) * | 1966-07-26 | W. Carlin William | Electrolytic production of chromic acid | |
US2099658A (en) * | 1933-11-09 | 1937-11-16 | Gilbert | Preparation of chromic acid and sparingly soluble chromates |
US2213249A (en) * | 1934-07-23 | 1940-09-03 | Armstrong Cork Co | Insulation board and method of making the same |
US3305463A (en) * | 1962-03-16 | 1967-02-21 | Pittsburgh Plate Glass Co | Electrolytic production of dichromates |
GB1399402A (en) * | 1972-02-10 | 1975-07-02 | Marley Homes Ltd | Reinforced woodwool slab |
DE2854228C2 (de) * | 1978-12-15 | 1983-11-24 | Ytong AG, 8000 München | Mehrschichtenplatte aus Gasbeton sowie Verfahren zu ihrer Herstellung |
FR2455984A1 (fr) * | 1979-05-10 | 1980-12-05 | Dvihally Sandor | Procede de fabrication de panneaux de particules |
CA1141640A (fr) * | 1979-06-08 | 1983-02-22 | Thomas A. Pilgrim | Elements de construction |
WO1983001410A1 (fr) * | 1981-10-26 | 1983-04-28 | Teare, John, W. | Procede et dispositif de production de panneaux en beton |
DE3313641C2 (de) * | 1983-04-15 | 1986-06-12 | M.A.N.- Roland Druckmaschinen AG, 6050 Offenbach | Vorrichtung zum Auftragen einer Schicht aus einer flüssigen feinkeramischen Masse auf einen Träger |
GB2236876A (en) * | 1989-10-12 | 1991-04-17 | Bpb Industries Plc | Control of the manufacture of plaster board |
DE9313351U1 (de) * | 1993-09-04 | 1993-11-04 | Wedi, Helmut, 48282 Emsdetten | Plattenförmiges Bauteil |
ES2107599T3 (es) * | 1992-10-29 | 1997-12-01 | Helmut Wedi | Procedimiento para la fabricacion de productos angulares semiacabados a partir de placas compuestas laminadas. |
-
1988
- 1988-08-27 DE DE3829125A patent/DE3829125A1/de not_active Withdrawn
-
1989
- 1989-08-08 MX MX017106A patent/MX171486B/es unknown
- 1989-08-15 DE DE8989115034T patent/DE58901743D1/de not_active Expired - Lifetime
- 1989-08-15 ES ES198989115034T patent/ES2032636T3/es not_active Expired - Lifetime
- 1989-08-15 EP EP89115034A patent/EP0356806B1/fr not_active Expired - Lifetime
- 1989-08-22 TR TR89/0693A patent/TR24639A/xx unknown
- 1989-08-24 JP JP1216182A patent/JP2839154B2/ja not_active Expired - Lifetime
- 1989-08-25 CA CA000609436A patent/CA1337808C/fr not_active Expired - Fee Related
- 1989-08-25 BR BR898904279A patent/BR8904279A/pt not_active Application Discontinuation
- 1989-08-25 AR AR89314754A patent/AR244351A1/es active
-
1991
- 1991-02-25 US US07/663,031 patent/US5071522A/en not_active Expired - Lifetime
Also Published As
Publication number | Publication date |
---|---|
BR8904279A (pt) | 1990-04-17 |
DE58901743D1 (de) | 1992-07-30 |
DE3829125A1 (de) | 1990-03-01 |
CA1337808C (fr) | 1995-12-26 |
TR24639A (tr) | 1991-12-25 |
EP0356806A2 (fr) | 1990-03-07 |
MX171486B (es) | 1993-10-29 |
US5071522A (en) | 1991-12-10 |
JP2839154B2 (ja) | 1998-12-16 |
JPH02102127A (ja) | 1990-04-13 |
ES2032636T3 (es) | 1993-02-16 |
EP0356806A3 (en) | 1990-04-18 |
AR244351A1 (es) | 1993-10-29 |
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