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US4087318A
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Oxygen-alkali delignification of lignocellulosic material in the presence of a manganese compound
Assignee: Mo och Domsjo AB
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Filing: 1976-12-27
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Granted: 1978-05-02
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Expires: 1996-12-27
Abstract
Abstract A process is provided for the delignification of lignocellulosic material wherein the lignocellulosic material, prior to the delignification, is treated with water or an aqueous solution to remove compounds which catalyze the degradation of carbohydrates and then the delignification is carried out with oxygen and alkali in the presence of a manganese compound to improve the selectivity of the delignification and increase the rate of delignification.
Inventors
- 👤 Hans Olof Samuelson
- 👤 Kjell Evert Abrahamsson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 20:20
CPC Classifications
D; D21; D21C; D21C9/00; D21C9/10; D21C9/1026; D21C9/1036; D21C1/00; D21C3/00; D21C3/22; D21C3/222; D21C9/1005
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
124 words
A process for the delignifcation of raw lignocellulosic material to produce cellulose pulp having a higher viscosity at a given Kappa number which comprises pretreating said lignocellulosic material with a liquid selected from the group consisting of water and aqueous solutions to remove from the lignocellulosic material metal ions and compounds which catalyze the degradation of carbohydrates, and then carrying out the delignification with oxygen and alkali at a pH within the range from about 7 to about 10 in the presence of a catalytically-active manganese compound added in an amount within the range from 0.01 to about 1% by weight Mn based on the dry weight of the lignocellulosic material to improve the selectivity of the delignification and increase the rate of delignification.
Claim 2
Dependent Claim
124 words
A process for the delignifcation of raw lignocellulosic material to produce cellulose pulp having a higher viscosity at a given Kappa number which comprises pretreating said lignocellulosic material with a liquid selected from the group consisting of water and aqueous solutions to remove from the lignocellulosic material metal ions and compounds which catalyze the degradation of carbohydrates, and then carrying out the delignification with oxygen and alkali at a pH within the range from about 7 to about 10 in the presence of a catalytically-active manganese compound added in an amount within the range from 0.01 to about 1% by weight Mn based on the dry weight of the lignocellulosic material to improve the selectivity of the delignification and increase the rate of delignification.
Claim 3
Dependent Claim
20 words
A process according to claim 1, in which the manganese compound is added prior to the start of the delignification.
Claim 4
Dependent Claim
35 words
A process according to claim 1, in which the manganese compound is added at an early stage of the delignification, and before dissolution of approximately 10% of the lignin content of the starting lignocellulosic material.
Claim 5
Dependent Claim
25 words
A process according to claim 1, in which the manganese compound is capable of supplying manganese ion to the delignification reaction in a catalytic form.
Claim 6
Dependent Claim
23 words
A process according to claim 1, in which the manganese compound is added to the lignocellulosic material at the start of the delignification.
Claim 7
Dependent Claim
20 words
A process according to claim 1, in which the manganese compound is added incrementally in the course of the delignification.
Claim 8
Dependent Claim
20 words
A process according to claim 1, in which the manganese compound is added continuously in the course of the delignification.
Claim 9
Dependent Claim
25 words
A process according to claim 1, in which the manganese compound is impregnated into the lignocellulosic material prior to the delignification with oxygen and alkali.
Claim 10
Dependent Claim
16 words
A process according to claim 1, in which the manganese compound is a bivalent manganous compound.
Claim 11
Dependent Claim
54 words
A process according to claim 9, in which the manganous compound is selected from the group consisting of manganous oxide, manganous chloride, manganous bromide, manganous hydroxide, manganous nitrite, manganous sulfate, manganous carbonate, manganous phosphate, manganous chlorate, manganous acetate, manganous formate, manganous oxalate, and complex salts of manganous ion with chelating inorganic and organic acids.
Claim 12
Dependent Claim
35 words
A process according to claim 1, in which the amount of manganese compound is within the range from about 0.05 to about 0.5% by weight Mn, based on the dry weight of the lignocellulosic material.
Claim 13
Dependent Claim
20 words
A process according to claim 1, wherein the pretreating liquid is an aqueous solution which contains a metal complexing agent.
Claim 14
Dependent Claim
12 words
A process according to claim 1, wherein the pretreating liquid is water.
Claim 15
Dependent Claim
15 words
A process according to claim 1, wherein the pretreating liquid is an aqueous acidic solution.
Claim 16
Dependent Claim
33 words
A process according to claim 1, wherein the pretreating liquid is an aqueous alkaline solution comprising at least one alkali selected from the group consisting of sodium carbonate, sodium bicarbonate, and sodium hydroxide.
Claim 17
Dependent Claim
19 words
A process according to claim 1, wherein the pretreating liquid is a waste liquor from the oxygen-alkali delignification process.
Claim 18
Dependent Claim
38 words
A process according to claim 11, wherein after the pretreatment but prior to the oxygen-alkali delignification the pretreated lignocellulosic material is washed with a member selected from the group consisting of water and acidic and alkaline aqueous solutions.
Claim 19
Dependent Claim
23 words
A process according to claim 1, wherein the oxygen-alkali delignification process is effected at an oxygen partial pressure of at least 5 bars.
Claim 20
Dependent Claim
39 words
A process according to claim 1 in which the lignocellulosic material is wood in the form of particles having a wood structure, and the oxygen-alkali delignification is carried out at an oxygen partial pressure of at least 10 bars.
Claim 21
Dependent Claim
28 words
A process according to claim 1, wherein the temperature for the major part of the delignification is maintained within the range from about 120° to about 160° C.
Claim 22
Dependent Claim
44 words
A process according to claim 1, in which the lignocellulosic material is wood in the form of particles having a wood structure, and the temperature is maintained within the range from about 130° to about 150° C for the major part of the delignification.
Claim 23
Dependent Claim
20 words
A process according to claim 1, wherein a magnesium compound is added as a cellulose degradation inhibitor during the delignification.
References Cited (Backward Citations)
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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) | 1981-05-01 | 1981-10-31 | 1982-05-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-05-01 | 1985-10-31 | 1986-05-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-05-01 | 1989-10-31 | 1990-05-02 | $7700.00 | Window Closed / Lapsed |