US4427490A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Delignification and bleaching process for lignocellulosic pulp with peroxide in the presence of metal additives
Assignee: International Paper Co
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Filing: 1981-04-13
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Granted: 1984-01-24
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Expires: 2001-04-13
Abstract
Abstract A process and solution for delignifying and brightening lignocellulosic pulp. The solution comprises from about 0.1 to about 5% by weight, based on oven-dried pulp of a peroxide and about 0.5 to about 20 mole percent, based on the moles of peroxide, of a metal ion selected from the group consisting of tungsten, molybdenum, chromium, osmium and selenium. The preferred process of this invention comprises contacting a lignocellulosic pulp with about 0.5 to about 20 mole percent, based on moles of peroxide, of a metal ion selected from the group consisting of tungsten, molybdenum, chromium, osmium and selenium at a temperature below about 50° C.; adjusting the pH of the resultant pulp slurry to between about 1 and about 7; adding 0.1 to about 5% by weight based on oven-dried pulp of peroxide and effecting pulp delignification and brightening at about 30° C. to about 100° C. until most of the peroxide has been consumed.
Inventors
- 👤 Robert C. Eckert
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 13:15
CPC Classifications
D; D21; D21C; D21C9/00; D21C9/10; D21C9/1026; D21C9/1036; D21C9/16; D21C9/163
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
105 words
A process for delignifying and brightening lignocellulosic pulp comprising maintaining the temperature of an aqueous hydrogen peroxide-containing pulp slurry between about 30° C. and 100° C. until the peroxide is substantially consumed, the pulp slurry comprising lignocellulosic pulp; from about 0.1 to about 5% by weight, based on oven-dried pulp, of hydrogen peroxide and about 0.5 to about 20 mole percent, based based on moles of the peroxide, of tungsten ion; and having a pH between about 3 and about 6; the peroxide and the tungsten ion, as present in the pulp slurry, consisting essentially of free peroxide, free tungsten ion and a peroxo-tungstate complex.
Claim 2
Dependent Claim
105 words
A process for delignifying and brightening lignocellulosic pulp comprising maintaining the temperature of an aqueous hydrogen peroxide-containing pulp slurry between about 30° C. and 100° C. until the peroxide is substantially consumed, the pulp slurry comprising lignocellulosic pulp; from about 0.1 to about 5% by weight, based on oven-dried pulp, of hydrogen peroxide and about 0.5 to about 20 mole percent, based based on moles of the peroxide, of tungsten ion; and having a pH between about 3 and about 6; the peroxide and the tungsten ion, as present in the pulp slurry, consisting essentially of free peroxide, free tungsten ion and a peroxo-tungstate complex.
Claim 3
Dependent Claim
17 words
The process of claim 1 wherein the pH is 5 and the slurry temperature is 77° C.
Claim 4
Dependent Claim
114 words
A process for delignifying and brightening lignocellulosic pulp comprising admixing lignocellulosic pulp with an aqueous metal solution consisting essentially of about 0.1 to about 5% by weight, based on oven-dried pulp, of a peroxide, about 0.5 to about 20 mole percent, based on moles of the peroxide, of a metal ion selected from the group consisting of tungsten, molybdenum, chromium, osmium and selenium, and sufficient acid to maintain the pH of the resultant pulp slurry between about 1 and about 7, the slurry having a consistency from about 1% to about 50%, and maintaining the pulp slurry at a temperature between about 30° C. and about 100° C. until the peroxide is substantially consumed.
Claim 5
Dependent Claim
114 words
A process for delignifying and brightening lignocellulosic pulp comprising admixing lignocellulosic pulp with an aqueous metal solution consisting essentially of about 0.1 to about 5% by weight, based on oven-dried pulp, of a peroxide, about 0.5 to about 20 mole percent, based on moles of the peroxide, of a metal ion selected from the group consisting of tungsten, molybdenum, chromium, osmium and selenium, and sufficient acid to maintain the pH of the resultant pulp slurry between about 1 and about 7, the slurry having a consistency from about 1% to about 50%, and maintaining the pulp slurry at a temperature between about 30° C. and about 100° C. until the peroxide is substantially consumed.
Claim 6
Dependent Claim
19 words
The process of claim 3 wherein the acid is added subsequent to admixing the pulp with the metal solution.
Claim 7
Dependent Claim
20 words
The process of claim 1 or 3 wherein the peroxide concentration is between about 0.5 and about 2% by weight.
Claim 8
Dependent Claim
11 words
The process of claim 3 wherein the peroxide is hydrogen peroxide.
Claim 9
Dependent Claim
11 words
The process of claim 3 wherein the metal ion is tungsten.
Claim 10
Dependent Claim
20 words
The process of claim 3 wherein the pH of the pulp slurry is maintained between about 3 and about 6.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-01-23 | 1987-07-25 | 1988-01-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-01-23 | 1991-07-25 | 1992-01-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-01-23 | 1995-07-25 | 1996-01-24 | $7700.00 | Window Closed / Lapsed |