WO1991003421A1 - High purity chloric acid - Google Patents
High purity chloric acid Download PDFInfo
- Publication number
- WO1991003421A1 WO1991003421A1 PCT/US1990/005008 US9005008W WO9103421A1 WO 1991003421 A1 WO1991003421 A1 WO 1991003421A1 US 9005008 W US9005008 W US 9005008W WO 9103421 A1 WO9103421 A1 WO 9103421A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- chloric acid
- solution
- weight
- percent
- aqueous
- Prior art date
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B11/00—Oxides or oxyacids of halogens; Salts thereof
- C01B11/12—Chloric acid
Definitions
- Chloric acid can be used in the formation of chlorine dioxide, a commercial bleaching and sanitizing agent.
- Chloric acid is a known compound which has been made in laboratory preparations by the reaction of barium chlorate with sulfuric acid to precipitate barium sulfate and produce a dilute aqueous solution of chloric acid which was concentrated by evaporation of water under partial vacuum.
- sodium chlorate is reacted with an acid such as
- Schlumberger teaches a process for producing chloric acid of high purity by passing an aqueous solution containing from 0.2 gram mole to 11 gram moles per liter of an alkali metal chlorate such as sodium chlorate through a selected cationic exchange resin at a temperature from 5o to 40o C.
- the proces produces an aqueous solution containing from 0.2 gram mole to about 4.0 gram moles of HClO 3 .
- chlorous acid [HCIO 2 ] is stated to be an intermediate in the formation.
- Decomposition of HOCl by both mechanisms is said to increase with concentration, temperature and exposure to light and are pH dependent.
- the first reaction mechanism is said to be accelerated by
- Chloric acid however, up to the present time, has not been commercially produced or available commercially because of the high manufacturing costs and/or the undesired
- chloric acid can be produced efficiently at substantially reduced production costs using a process which can be operated commercially.
- the chloric acid solutions produced are of high purity and are stable at ambient conditions.
- a process for producing chloric acid which comprises converting an aqueous solution of hypochlorous acid containing at least 20 percent by weight of HOCl at a temperature in the range of from about 10° to about 120 oC. to a reaction mixture
- the novel process of the present invention employs as the starting material a concentrated solution of high purity hypochlorous acid, HOCl.
- One method of producing high purity concentrated HOCl solutions is that in which gaseous mixtures, having high concentrations of hypochlorous acid vapors and chlorine monoxide gas and controlled amounts of water vapor are produced, for example, by the process described by J. P. Brennan et al in U.S. Patent No. 4,147,761, which is
- the gaseous mixture is then converted to a concentrated hypochlorous acid solution as described in WO 90/05111 published May 17, 1990 by J. K. Melton, et. al. which is incorporated in its entirety by reference.
- the concentrated hypochlorous acid solution employed as a reactant contains at least 20 percent by weight of HOCl.
- Preferred solutions are those having concentrations in the range of from about 30 to about 60, and more preferably from about 40 to about 55 percent by weight of HOCl.
- the solution is substantially free of ionic impurities such as chloride ions and alkali metal ions and has low concentrations of dissolved chlorine.
- concentrations of the chloride ion are preferably less than about 50 parts per million and the alkali metal ion concentration is preferably less than about 50 parts per million.
- the dissolved chlorine concentration in the hypochlorous acid solution is normally less than about 2 percent, and preferably less than about 1 percent by weight.
- the concentrated hypochlorous acid is converted to chloric acid in any suitable manner and because the
- hypochlorous acid reagent is of high purity, the conversion is believed to produce chloric acid according to the following reactions:
- conversion of the concentrated hypochlorous acid to chloric acid takes place in an open vessel. Under these conditions the gaseous by-products are released as formed, for example, to a scrubbing apparatus containing an alkaline solution.
- Suitable temperatures are those, for example, in the range of from about 10 to about 120o at autogenous pressures.
- the conversion times are directly related to the temperature, however, as the conversion temperature increases, the yield of chloric acid is reduced. Therefore the hypochlorous acid conversion, where the by-product gases are released or
- a dilute aqueous solution of chloric acid is produced which is may be further concentrated.
- the chloric acid is produced by heating the hypochlorous acid solution at elevated temperature
- the concentrated hypochlorous acid solution may be heated at temperatures in the range of from about 40 to about 120, preferably in the range of from about 50 to about 110 oC, and more preferably in the range of from about 60 to about 100oC.
- chloric acid solution produced by the process of the invention is dilute, i.e. less than about 10 percent by weight of HCIO 3 , the chloric acid solution is further
- any residual hypochlorous acid is converted to chloric acid product.
- Concentration is suitably accomplished by heating the chloric acid solution at temperatures above about 40oC, for example at temperatures in the range of from about 40 to about 120 oC, preferably at from about 70 to about 120 oC. and more preferably at from about 95 to about 120 oC.
- the chloric acid solutions may also be concentrated by vacuum distillation. Any suitable vacuum pressures may be used such as those in the range of from about 0.01 to about 100 mm Hg. pressure
- the highly pure chloric acid solutions which are produced by the novel process of the present invention contain at least about 10 percent, for example 12 percent or greater, by weight of HClO 3 . Concentrated solutions up to about 45% by weight of HClO 3 may be produced. Preferred chloric acid solutions are those having from about 15% to about 40%, and more preferably 18% to about 35% by weight of HClO 3 .
- the highly pure concentrated solutions produced i.e. those above about 30% by weight of HClO 3 , are surprisingly stable and can be stored safely without significant decomposition for extended periods of time.
- hypochlorous acid containing 30% by weight of HOCl was added to a large open vessel at ambient temperature and pressure.
- the solution was analyzed
- a solution containing 22.8% by weight of HClO 3 produced by the process of the invention was further concentrated by heating at 95oC in an open vessel.
- the chloric acid product recovered contained 43.34% by weight of HClO 3 .
- Hypochlorous acid (44%, 600 g.) was heated in an open vessel at 95o for 1 hour.
- the product solution contained 6.3% HOCl and 5.5% HClO 3 (yield 29%).
- the product solution may be further concentrated by evaporation of water, for example, by the method of Example 1.
Abstract
A process for producing chloric acid which comprises converting an aqueous solution of hypochlorous acid containing at least 20 percent by weight of HOCl at a temperature in the range of from about 10 to about 120 °C to a reaction mixture comprising a dilute aqueous solution of chloric acid and gaseous by-products while continuously removing the gaseous by-products to produce a chloric acid solution containing about 10 percent or greater by weight of HClO3. Using the novel process it has been found that chloric acid can be produced efficiently at substantially reduced production costs using a process which can be operated commercially. In addition, the chloric acid solutions are produced in high concentrations and high purity being substantially free of impurities such as alkali metal ions, chloride ions and sulfate ions.
Description
High Purity Chloric Acid
Cross Reference to Related Application
This application is a continuation-in-part of
application U.S. Serial No. 403,279, filed September 5, 1989.
Background of the Invention
Field of the Invention
This invention relates to the production of chloric acid, HClO3. Chloric acid can be used in the formation of chlorine dioxide, a commercial bleaching and sanitizing agent.
Description of the Prior Art Chloric acid is a known compound which has been made in laboratory preparations by the reaction of barium chlorate with sulfuric acid to precipitate barium sulfate and produce a dilute aqueous solution of chloric acid which was concentrated by evaporation of water under partial vacuum. In another method sodium chlorate is reacted with an acid such as
hydrochloric acid or sulfuric acid to produce an aqueous solution of chloric acid containing sulfate or chloride ions as impurities. In addition, commercial processes for
producing chlorine dioxide form chloric acid as an
intermediate.
U.S. Patent 3,810,969 issued May 14, 1974 to A.A.
Schlumberger teaches a process for producing chloric acid of high purity by passing an aqueous solution containing from 0.2 gram mole to 11 gram moles per liter of an alkali metal chlorate such as sodium chlorate through a selected cationic exchange resin at a temperature from 5º to 40º C. The proces produces an aqueous solution containing from 0.2 gram mole to about 4.0 gram moles of HClO3.
Kirk-Othmer : "Encyclopedia of Chemical Technology" 3rd edition, vol. 5, page 587 teach that the decomposition of dilute hypochlorous acid solutions (1 M) can occur in two ways:
in the second mechanism, chlorous acid [HCIO2] is stated to be an intermediate in the formation. Decomposition of HOCl by both mechanisms is said to increase with concentration, temperature and exposure to light and are pH dependent. The first reaction mechanism is said to be accelerated by
catalysts and the second mechanism favored by the pressure of electrolytes such as the chloride ion. The reference,
however, has no teachings regarding the decomposition of concentrated hypochlorous acid solutions.
Chloric acid, however, up to the present time, has not been commercially produced or available commercially because of the high manufacturing costs and/or the undesired
impurities present in the solutions of HClO3 made by these reactions.
Summary of the Invention
Now it has been found that chloric acid can be produced efficiently at substantially reduced production costs using a process which can be operated commercially. In addition, the chloric acid solutions produced are of high purity and are stable at ambient conditions.
In accordance with this invention, there is provided a process for producing chloric acid which comprises converting an aqueous solution of hypochlorous acid containing at least 20 percent by weight of HOCl at a temperature in the range of from about 10° to about 120 ºC. to a reaction mixture
comprising a dilute aqueous solution of chloric acid and gaseous by-products and continuously removing the gaseous by-products to produce a chloric acid solution containing about 10 percent or greater by weight of HClO3.
Detailed Description of the Invention The novel process of the present invention employs as the starting material a concentrated solution of high purity hypochlorous acid, HOCl. One method of producing high purity concentrated HOCl solutions is that in which gaseous mixtures, having high concentrations of hypochlorous acid vapors and chlorine monoxide gas and controlled amounts of water vapor are produced, for example, by the process described by J. P. Brennan et al in U.S. Patent No. 4,147,761, which is
incorporated in its entirety by reference. The gaseous mixture is then converted to a concentrated hypochlorous acid solution as described in WO 90/05111 published May 17, 1990 by J. K. Melton, et. al. which is incorporated in its entirety by reference.
The concentrated hypochlorous acid solution employed as a reactant contains at least 20 percent by weight of HOCl. Preferred solutions are those having concentrations in the range of from about 30 to about 60, and more preferably from about 40 to about 55 percent by weight of HOCl. The solution is substantially free of ionic impurities such as chloride ions and alkali metal ions and has low concentrations of dissolved chlorine. For example, concentrations of the chloride ion are preferably less than about 50 parts per million and the alkali metal ion concentration is preferably less than about 50 parts per million. The dissolved chlorine concentration in the hypochlorous acid solution is normally less than about 2 percent, and preferably less than about 1 percent by weight.
The concentrated hypochlorous acid is converted to chloric acid in any suitable manner and because the
hypochlorous acid reagent is of high purity, the conversion is believed to produce chloric acid according to the following reactions:
In one embodiment of the process of the invention conversion of the concentrated hypochlorous acid to chloric acid takes place in an open vessel. Under these conditions the gaseous by-products are released as formed, for example, to a scrubbing apparatus containing an alkaline solution.
Suitable temperatures are those, for example, in the range of from about 10 to about 120º at autogenous pressures. The conversion times are directly related to the temperature, however, as the conversion temperature increases, the yield of
chloric acid is reduced. Therefore the hypochlorous acid conversion, where the by-product gases are released or
continuously removed, is preferably at from about 25 to about 70ºC. A dilute aqueous solution of chloric acid is produced which is may be further concentrated.
In a preferred embodiment, the chloric acid is produced by heating the hypochlorous acid solution at elevated
temperatures while maintaining the gaseous by-products formed in contact with the reaction mixture during the reaction period. This can be accomplished, for example, by carrying out the process in a sealed reactor at the autogenous
pressures attained wherein a substantial increase in the yield of chloric acid results. For example, the concentrated hypochlorous acid solution may be heated at temperatures in the range of from about 40 to about 120, preferably in the range of from about 50 to about 110 ºC, and more preferably in the range of from about 60 to about 100ºC.
Where the chloric acid solution produced by the process of the invention is dilute, i.e. less than about 10 percent by weight of HCIO3, the chloric acid solution is further
concentrated by removing a portion of the water by
evaporation. During evaporation any residual hypochlorous acid is converted to chloric acid product. Concentration is suitably accomplished by heating the chloric acid solution at temperatures above about 40ºC, for example at temperatures in the range of from about 40 to about 120 ºC, preferably at from about 70 to about 120 ºC. and more preferably at from about 95 to about 120 ºC.
The chloric acid solutions may also be concentrated by vacuum distillation. Any suitable vacuum pressures may be used such as those in the range of from about 0.01 to about 100 mm Hg. pressure
The highly pure chloric acid solutions which are produced by the novel process of the present invention contain
at least about 10 percent, for example 12 percent or greater, by weight of HClO3. Concentrated solutions up to about 45% by weight of HClO3 may be produced. Preferred chloric acid solutions are those having from about 15% to about 40%, and more preferably 18% to about 35% by weight of HClO3. The highly pure concentrated solutions produced i.e. those above about 30% by weight of HClO3, are surprisingly stable and can be stored safely without significant decomposition for extended periods of time.
The novel process of the present invention is further illustrated by the following examples with no intention of being limited thereby. All parts and percentages are by weight unless otherwise indicated.
EXAMPLE 1
A solution of hypochlorous acid containing 30% by weight of HOCl was added to a large open vessel at ambient temperature and pressure. The solution was analyzed
periodically and when the reaction had produced a solution containing 6.0% of HClO3, 5.3% of HOCl and 0.1% HCl by
weight, the solution was heated at 30ºC and a solution
containing 7.8% HClO3, 0.6% HOCl and 0.1% HCl by weight produced. This chloric acid solution was further concentrated by vacuum distillation at 20-24ºC and about 0.1 mm Hg to a solution containing 20.03% HClO3 and less than 0.1% by
weight of either HOCl or HCl.
EXAMPLE 2
A concentrated solution of hypochlorous acid containing 41% by weight of HOCl was placed in the large open vessel employed in Example 1, and allowed to remain at room
temperature for 24 hours. The solution was then concentrated by vacuum evaporation at 25ºC to produce a chloric acid solution containing 23.5% by weight of HClO3. The analyses are as follows:
TABLE I
Initial After 24 hrs. After Concentration
Weight %
HClO3 14.31 23.51
HOCl 41 0.80 0.12
HCl BDL* BDL*
*Below detectable limits
EXAMPLE 3
A concentrated hypochlorous acid solution (600g.) containing 40.54% by wt. of HOCl was poured into a sealed reactor and heated at 55°C.. The gases produced were fed to a caustic scrubber. Following the reaction a solution (454.8 g) containing 11.91%
HClO3, 4.92% HOCl and 0.1% HCl was produced. The yield of HClO3 based on HOCl was 71%. The analyses of the reaction solution and the scrubber solution (1124.7 g.) are as follows:
TABLE II
Initial After HOCl Caustic
Solution Conversion Scrubber
Weight %
HOCl 40.54 4.92
HClO3 0.29 11.91
HCl 0.12 0.1
NaOCl 10.93
NaClO3 0.69
NaCl 10.07
EXAMPLE 4
A concentrated hypochlorous acid solution containing 40.54% by wt. of HOCl (600g.) was heated in the sealed reactor used in Example 3 at a temperature of 95°C. The yield of HClO3 (445.5 g) based on HOCl was 81%. The analyses are given in Table III below.
TABLE III
Initial After HOCl
Solution Conversion
Weight %
HOCl 40.89 2.45
HCIO3 1.04 13.74
HCl 0.54 0.22
EXAMPLE 5
A solution containing 22.8% by weight of HClO3 produced by the process of the invention was further concentrated by heating at 95ºC in an open vessel. The chloric acid product recovered contained 43.34% by weight of HClO3.
EXAMPLE 6
A solution containing 15% by weight of HCIO3 was concentrated to 28% by weight by boiling under atmospheric pressure at 102-4ºC. Recovery of the chloric acid value was 97.2%. The total time required for the concentration was 45 minutes, of which 13 minutes was required to heat the initial solution to boiling. No evidence of chlorine or chlorine dioxide emission was observed.
EXAMPLES 7-8
Chloric acid solutions containing 30% and 37.87% by weight of HClO3 were produced in the
process of the invention.
An aliquot ( 1000 ml.) of each solution was placed in an open vessel and stored at 30ºC. and 40ºC. During the storage period, the solution was
periodically analyzed by titrimetry for the
concentration of HClO3. The results are given in
Table IV below.
TABLE IV
STABILITY OF HCLO3, SOLUTIONS AT 30 AND 40 DEG C
30 DEG. C. 40 DEG. C
Wt% HClO3 Days Wt% HClO3
Example 7
30.01 0 30.01
29.79 3 29.78
29.99 6 29.87
30.01 14 30.03
30.68 26 30.45
30.37 44 30.42
30.34 64 30.07
30.54 81 30.46
Example 8
37.87 0 37.87
37.78 3 37.87
37.84 6 38.01
38.13 14 38.40
38.58 26 38.51
38.27 44 38.70
37.89 64 38.73
38.30 81 40.12
39.27 121 40.93
EXAMPLE 9
Hypochlorous acid (44%, 600 g.) was heated in an open vessel at 95º for 1 hour. The product solution contained 6.3% HOCl and 5.5% HClO3 (yield 29%). The product solution may be further concentrated by evaporation of water, for example, by the method of Example 1.
Claims
1. A process for producing an aqueous chloric acid solution which is characterized by
converting an aqueous solution of hypochlorous acid containing at least 20 percent by weight of HOCl at a temperature in the range of from about 10º to about 120ºC. to a reaction mixture comprising an aqueous solution of chloric acid and gaseous by-products while continuously removing the gaseous by-products to produce an aqueous chloric acid solution containing about 10 percent or greater by weight of HClO3.
2. The process of claim 1 characterized in that the aqueous solution of hypochlorous acid contains from about 20 to about 60 percent by weight of HOCl.
3. The process of claim 1 characterized in that the aqueous solution of chloric acid is
concentrated at a temperature in the range of from about 40º to about 120º.
4. The process of claim 1 characterized in that the dilute aqueous solution of chloric acid is concentrated by vacuum distillation.
5. The process of claim 4 characterized in that the conversion temperature is in the range of from about 25º to about 70º.
6. A process for the production of an aqueous chloric acid solution characterized by heating an aqueous solution of hypochlorous acid containing at least 20 percent by weight of HOCl at above ambient temperature to form a reaction mixture comprised of an aqueous chloric acid solution and gaseous by-products, retaining the gaseous by-products in contact with the chloric acid solution, and producing an aqueous chloric acid solution containing about 10 percent or greater by weight of HClO3.
7. The process of claim 6 characterized in that the solution of hypochlorous acid is heated at a temperature in the range of from about 40º to about 120ºC.
8. The process of claim 6 characterized in that the solution of hypochlorous acid contains from about 20 to about 60 percent by weight of HOCl.
.
9. The process of claim 8 characterized in that the solution of hypochlorous acid is heated at a temperature in the range of from about 50º to about 110ºC.
10. The process of claim 6 characterized in that the solution of hypochlorous acid contains from about 30 to about 55 percent by weight of HOCl.
11. The process of claim 10 characterized in that the solution of hypochlorous acid is heated at a temperature in the range of from about 60º to about 100ºC.
12. The process of claim 6 characterized in that the aqueous chloric acid solution is further concentrated by evaporation.
13. The process of claim 12 characterized in that the aqueous chloric acid solution is evaporated at a temperature of from about 70º to about 120ºC.
14. The process of claim 12 characterized in that the aqueous chloric acid solution is concentrated by vacuum distillation.
15. The process of claim 14 characterized in that the aqueous chloric acid solution is evaporated at a temperature of from about 95º to about 120ºC.
16. The process of claim 1 characterized in that the chloric acid solution contains about 12 percent or greater by weight of HClO3.
17. The process of claim 3 characterized in that the aqueous chloric acid solution produced
contains from about 15 to about 40 percent by weight of HClO3.
18. The process of claim 6 characterized in that the chloric acid solution contains about 12 percent or greater by weight of HClO3.
19. The process of claim 10 characterized in that the aqueous chloric acid solution produced
contains from about 15 to about 40 percent by weight of HClO3.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FI920376A FI920376A0 (en) | 1989-09-05 | 1992-01-28 | KLORSYRA MED HOEG RENHETSGRAD. |
| NO92920389A NO920389L (en) | 1989-09-05 | 1992-01-29 | CHLORIC ACID OF HIGH PURITY |
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US40327989A | 1989-09-05 | 1989-09-05 | |
| US403,279 | 1989-09-05 | ||
| US55228290A | 1990-07-13 | 1990-07-13 | |
| US552,282 | 1990-07-13 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| WO1991003421A1 true WO1991003421A1 (en) | 1991-03-21 |
Family
ID=27018232
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| PCT/US1990/005008 WO1991003421A1 (en) | 1989-09-05 | 1990-09-04 | High purity chloric acid |
Country Status (5)
| Country | Link |
|---|---|
| EP (1) | EP0490978A4 (en) |
| JP (1) | JPH05500201A (en) |
| AU (1) | AU6435790A (en) |
| FI (1) | FI920376A0 (en) |
| WO (1) | WO1991003421A1 (en) |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2347151A (en) * | 1940-04-30 | 1944-04-18 | Shell Dev | Production of hypohalous acid solutions |
| GB984378A (en) * | 1962-10-24 | 1965-02-24 | Murgatroyds Salt & Chem | Improvements in or relating to sodium hypochlorite production |
-
1990
- 1990-09-04 WO PCT/US1990/005008 patent/WO1991003421A1/en not_active Application Discontinuation
- 1990-09-04 JP JP51303190A patent/JPH05500201A/en active Pending
- 1990-09-04 AU AU64357/90A patent/AU6435790A/en not_active Abandoned
- 1990-09-04 EP EP19900914002 patent/EP0490978A4/en not_active Withdrawn
-
1992
- 1992-01-28 FI FI920376A patent/FI920376A0/en unknown
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2347151A (en) * | 1940-04-30 | 1944-04-18 | Shell Dev | Production of hypohalous acid solutions |
| GB984378A (en) * | 1962-10-24 | 1965-02-24 | Murgatroyds Salt & Chem | Improvements in or relating to sodium hypochlorite production |
Non-Patent Citations (6)
| Title |
|---|
| "Supplement to Mellor's Comprehensive Treatise on Inorganic and Theoretical Chemistry" Supplement II, published 1956 by Longmans, GREEN AND CO. (LONDON) see pages 546-549. * |
| GERHARTZ, Ed., "Ullmann's Encyclopedia of Industrial Chemistry, 5th Edition, Vol. A6, published 1986, see page 501. * |
| Kirk-Othmer, "Encyclopedia of Chemical Technology, 3rd Ed., Vol. 5, published 1979 by JOHN WILEY & SONS (New York) see pages 587-588. * |
| Masschelein, "Chlorine Dioxide, Chemical and Environmental Impact of Oxychlorine Compounds" Published 1979 by ANN ARBOR Science (Michigan) see pages 9-11. * |
| See also references of EP0490978A4 * |
| STECHER, Ed., "The Merck Index" 8th Edition, published 1968 by Merck & Co., Inc. (New Jersey), see page 236. * |
Also Published As
| Publication number | Publication date |
|---|---|
| EP0490978A4 (en) | 1992-08-12 |
| JPH05500201A (en) | 1993-01-21 |
| AU6435790A (en) | 1991-04-08 |
| EP0490978A1 (en) | 1992-06-24 |
| FI920376A0 (en) | 1992-01-28 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| NO309375B1 (en) | Process for continuous production of chlorine dioxide | |
| NO309321B1 (en) | Process for continuous production of chlorine dioxide | |
| EP0513167B1 (en) | Process for the production of highly pure concentrated solutions of potassium hypochlorite | |
| EP0366636B1 (en) | A process for the production of chlorine dioxide | |
| CA1333518C (en) | Process for production of chlorine dioxide | |
| EP0646095B1 (en) | Process for producing chlorine dioxide | |
| US5093097A (en) | Process for the production of chlorine dioxide | |
| FI112352B (en) | Process for the production of chlorine dioxide | |
| WO1991003421A1 (en) | High purity chloric acid | |
| US5433938A (en) | Chlorine-destruct method | |
| US5322677A (en) | Process for producing concentrated hypochlorous acid solutions | |
| EP0131378B2 (en) | Process for the production of chlorine dioxide | |
| JPH0122356B2 (en) | ||
| US6251357B1 (en) | High purity alkali metal chlorite and method of manufacture | |
| US4609472A (en) | Process for removal of alkali metal chlorate from alkali metal chloride brines | |
| US3660030A (en) | Method of preparing nitrosyl chloride | |
| CA1116831A (en) | Versatile process for generating chlorine dioxide | |
| US3505010A (en) | Manufacture of ammonium bromide and carbon monoxide from polybromomethanes | |
| EP1299313B1 (en) | Process for the debromination of an aqueous salt solution using ozone |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| AK | Designated states |
Kind code of ref document: A1 Designated state(s): AU BB BG BR CA FI HU JP KR LK MC MG MW NO RO SD SU |
|
| AL | Designated countries for regional patents |
Kind code of ref document: A1 Designated state(s): AT BE BF BJ CF CG CH CM DE DK ES FR GA GB IT LU ML MR NL SE SN TD TG |
|
| WWE | Wipo information: entry into national phase |
Ref document number: 920376 Country of ref document: FI |
|
| WWE | Wipo information: entry into national phase |
Ref document number: 1990914002 Country of ref document: EP |
|
| WWP | Wipo information: published in national office |
Ref document number: 1990914002 Country of ref document: EP |
|
| NENP | Non-entry into the national phase |
Ref country code: CA |
|
| WWW | Wipo information: withdrawn in national office |
Ref document number: 1990914002 Country of ref document: EP |