US4096029A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Cellulosic pulp delignification using an acidic bromine-chlorine mixture
Assignee: Dow Chemical Co
•
Filing: 1976-04-26
•
Granted: 1978-06-20
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Expires: 1996-04-26
Abstract
Abstract Efficient lignin removal from cellulosic pulp with decreased cellulose degradation is attained by replacing chlorine with an acidic bromine-chlorine mixture in acidic chlorination of the pulp.
Inventors
- 👤 Jack F. Mills
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 18:58
CPC Classifications
D; D21; D21C; D21C9/00; D21C9/10; D21C9/12
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
65 words
In a liquid phase process for delignification of cellulosic pulp involving halogenation and extraction stages wherein the halogenation is conducted by contacting such pulp with chlorine under acidic conditions and wherein lignin is extracted from such pulp in one or more alkaline extraction stages; the improvement comprising replacing the chlorine with an acidic bromine-chlorine mixture comprising between about 10 and about 70 weight percent bromine.
Claim 2
Dependent Claim
65 words
In a liquid phase process for delignification of cellulosic pulp involving halogenation and extraction stages wherein the halogenation is conducted by contacting such pulp with chlorine under acidic conditions and wherein lignin is extracted from such pulp in one or more alkaline extraction stages; the improvement comprising replacing the chlorine with an acidic bromine-chlorine mixture comprising between about 10 and about 70 weight percent bromine.
Claim 3
Dependent Claim
19 words
A process of claim 1 wherein the bromine-chlorine mixture comprises between about 20 and about 60 weight percent bromine.
Claim 4
Dependent Claim
19 words
A process of claim 1 wherein the bromine-chlorine mixture comprises between about 25 and about 45 weight percent bromine.
Claim 5
Dependent Claim
15 words
A process of claim 1 wherein the process further involves one or more oxidation stages.
Claim 6
Dependent Claim
14 words
A process of claim 4 wherein the process comprises sequentially halogenation, extraction, and oxidation.
Claim 7
Dependent Claim
16 words
A process of claim 4 wherein the process comprises sequentially halogenation, extraction, oxidation, extraction and oxidation.
Claim 8
Dependent Claim
30 words
A process of claim 1 wherein the concentration of the bromine-chlorine mixture is between about 4 and about 14 weight percent based on the dry weight of the cellulosic pulp.
Claim 9
Dependent Claim
30 words
A process of claim 1 wherein the concentration of the bromine-chlorine mixture is between about 6 and about 14 weight percent based on the dry weight of the cellulosic pulp.
Claim 10
Dependent Claim
30 words
A process of claim 1 wherein the concentration of the bromine-chlorine mixture is between about 6 and about 10 weight percent based on the dry weight of the cellulosic pulp.
Claim 11
Dependent Claim
30 words
A process of claim 1 wherein the concentration of the bromine-chlorine mixture is between about 6 and about 8 weight percent based on the dry weight of the cellulosic pulp.
Claim 12
Dependent Claim
24 words
A process of claim 1 wherein the halogenation is conducted in the liquid phase at a pH of between about 1 and about 3.5.
Claim 13
Dependent Claim
16 words
A process of claim 1 wherein the cellulosic pulp is pulp prepared by the sulfate process.
Claim 14
Dependent Claim
20 words
A process of claim 1 wherein the cellulosic pulp exhibits a pre-delignification permanganate number between about 15 and about 35.
Claim 15
Dependent Claim
20 words
A process of claim 13 wherein the cellulosic pulp exhibits a post-delignification permanganate number between about 3 and about 10.
Claim 16
Dependent Claim
20 words
A process of claim 1 wherein the cellulosic pulp exhibits a post-delignification permanganate number between about 3 and about 10.
Claim 17
Dependent Claim
20 words
The process of claim 1 wherein the cellulosic pulp exhibits a post-delignification permanganate number between about 3 and about 6.
Claim 18
Dependent Claim
45 words
The process of claim 1 wherein the bromine-chlorine mixture comprises between about 10 and about 45 weight percent bromine and wherein the concentration of the bromine-chlorine mixture is between about 6 and about 8 weight percent based upon the dry weight of the cellulosic pulp.
References Cited (Backward Citations)
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Cited
US1942622A
Cited
US2461105A
Cited
US2989519A
Cited
US3150919A
Cited
US3433702A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1981-06-19 | 1981-12-19 | 1982-06-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-06-19 | 1985-12-19 | 1986-06-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-06-19 | 1989-12-19 | 1990-06-20 | $7700.00 | Window Closed / Lapsed |