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US4645579A
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Preparation of aqueous hydroxylamine solutions
Assignee: BASF SE
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Filing: 1984-12-24
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Granted: 1987-02-24
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Expires: 2004-12-24
Abstract
Abstract Aqueous solutions of hydroxylamine are prepared from aqueous hydroxylammonium salt solutions by electrodialysis by a method in which the aqueous hydroxylammonium salt solution is fed into the middle zone of an electrolysis cell, which is divided into a cathode zone, an anode zone and a middle zone by means of semipermeable membranes, and is electrolyzed, and the catholyte used is an alkali metal hydroxide solution containing ammonia and/or amines.
Inventors
- 👤 Franz-Josef Weiss
- 👤 Wolfgang Habermann
- 👤 Peter Hammes
- 👤 Elmar Frommer
- 👤 Erwin Thomas
- 👤 Peter Thoma
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 22:05
CPC Classifications
C; C01; C01B; C01B21/00; C01B21/082; C01B21/14; C01B21/1409; C01B21/1445; B; B01; B01D; B01D61/00; B01D61/42; B01D61/44
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
125 words
A process for the preparation of an aqueous solution of hydroxylamine from an aqueous hydroxylammonium salt solution by electrodialysis, the aqueous hydroxylammonium salt solution being fed into the middle zone of an electrolysis cell having anion selective membrances which is divided into a cathode zone, an anode zone and a middle zone by means of semipermeable membrances, and being electrolyzed, wherein the catholyte used is an aqueous alkali metal hydroxide solution containing a member selected from the group consisting of ammonia, primary, secondary or tertiary amines which possess alkyl radicals of 1 to 4 carbon atoms at the nitrogen atom which can have a hydroxy or alkoxy group as a substitutent, cyclic amines and polyamines obtainable by reacting amines with ethylene imine, or mixtures thereof.
Claim 2
Dependent Claim
125 words
A process for the preparation of an aqueous solution of hydroxylamine from an aqueous hydroxylammonium salt solution by electrodialysis, the aqueous hydroxylammonium salt solution being fed into the middle zone of an electrolysis cell having anion selective membrances which is divided into a cathode zone, an anode zone and a middle zone by means of semipermeable membrances, and being electrolyzed, wherein the catholyte used is an aqueous alkali metal hydroxide solution containing a member selected from the group consisting of ammonia, primary, secondary or tertiary amines which possess alkyl radicals of 1 to 4 carbon atoms at the nitrogen atom which can have a hydroxy or alkoxy group as a substitutent, cyclic amines and polyamines obtainable by reacting amines with ethylene imine, or mixtures thereof.
Claim 3
Dependent Claim
22 words
A process as claimed in claim 1, wherein the content of molecular oxygen in the middle zone is less than 20 ppm.
Claim 4
Dependent Claim
25 words
A process as claimed in claim 1, wherein the hydroxylammonium salt solution used contains a stabilizer which forms a chelate with metal ions for hydroxylamine.
Claim 5
Dependent Claim
21 words
A process as claimed in claim 1, wherein the hydroxylammonium salt solution used contains less than 1 ppm of heavy metals.
Claim 6
Dependent Claim
31 words
A process as claimed in claim 1, wherein the catholyte contains from 0.001 to 50% by weight of a member selected from the group consisting of ammonia, amines or mixtures thereof.
Claim 7
Dependent Claim
24 words
A process as claimed in claim 1, wherein the semipermeable membrances are weakly basic, at least on the sides which face the middle zone.
Claim 8
Dependent Claim
16 words
A process as claimed in claim 6, wherein the semipermeable membrances contain weakly basic ion exchangers.
Claim 9
Dependent Claim
30 words
A process as claimed in claim 6, wherein the semipermeable membrances contain zirconium oxide hydroxide, titanium oxide hydroxide, synthetic hydroxylapatite or zirconium aluminum oxide hydroxide, or a mixture of these.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-02-23 | 1990-08-25 | 1991-02-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-02-23 | 1994-08-25 | 1995-02-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-02-23 | 1998-08-25 | 1999-02-24 | $7700.00 | Window Closed / Lapsed |