US4050981A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for the delignification of lignocellulosic material by maintaining a concentration of carbon monoxide in the presence of oxygen and alkali
Assignee: Mo och Domsjo AB
•
Filing: 1975-06-11
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Granted: 1977-09-27
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Expires: 1995-06-11
Abstract
Abstract Process for improving the selectivity of delignification of lignocellulosic material in the presence of oxygen gas and alkali by maintaining a carbon monoxide content in the gas phase within the range from about 1% to about 12% by volume. The carbon monoxide concentration is maintained by withdrawing carbon monoxide and oxygen gas from the delignification, and separating and recycling withdrawn oxygen gas.
Inventors
- 👤 Allan Geoffrey Jamieson
- 👤 Hans Olof Samuelson
- 👤 Leif Ake Smedman
- 👤 Kent Ivar Sondell
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 15:59
CPC Classifications
D; D21; D21C; D21C9/00; D21C9/10; D21C9/1068
Claims Analysis
Total Claims: 38
Claim 1
Independent Claim
81 words
A process for the delignification of lignocellulosic material which comprises carrying out the delignification with oxygen gas and alkali in the presence of a gas phase comprising oxygen gas and carbon monoxide wherein the carbon monoxide is in a concentration within the range from about 1% to about 12% by volume of the gas phase while maintaining the carbon monoxide concentration within said range by withdrawing carbon monoxide and oxygen gas from the delignification, and separating and recycling withdrawn oxygen gas.
Claim 2
Dependent Claim
81 words
A process for the delignification of lignocellulosic material which comprises carrying out the delignification with oxygen gas and alkali in the presence of a gas phase comprising oxygen gas and carbon monoxide wherein the carbon monoxide is in a concentration within the range from about 1% to about 12% by volume of the gas phase while maintaining the carbon monoxide concentration within said range by withdrawing carbon monoxide and oxygen gas from the delignification, and separating and recycling withdrawn oxygen gas.
Claim 3
Dependent Claim
29 words
A process according to claim 1, in which the amount of carbon monoxide is at most 90% of the concentration corresponding to the explosion limit of the oxygen-containing gas.
Claim 4
Dependent Claim
25 words
A process according to claim 1, in which the amount of carbon monoxide is within the range from about 2% to about 10% by volume.
Claim 5
Dependent Claim
25 words
A process according to claim 1, in which the amount of carbon monoxide is within the range from about 4% to about 9% by volume.
Claim 6
Dependent Claim
23 words
A process according to claim 1, which includes flowing the gas phase in contact with a flow of the lignocellulosic material during delignification.
Claim 7
Dependent Claim
18 words
A process according to claim 5, in which the gas phase is flowed countercurrently to the lignocellulosic material.
Claim 8
Dependent Claim
18 words
A process according to claim 1, in which carbon monoxide is removed from the oxygen gas before recycling.
Claim 9
Dependent Claim
17 words
A process according to claim 7, in which the carbon monoxide is removed by absorption or adsorption.
Claim 10
Dependent Claim
16 words
A process according to claim 7, in which the carbon monoxide is oxidized to carbon dioxide.
Claim 11
Dependent Claim
23 words
A process according to claim 1, in which oxygen and carbon monoxide are removed from the delignification and transferred to another delignification process.
Claim 12
Dependent Claim
27 words
A process according to claim 1, in which oxygen and carbon monoxide are removed from a delignification of cellulose pulp and transferred to an oxygen-gas-alkali digestion process.
Claim 13
Dependent Claim
71 words
A process according to claim 1, in which the process is carried out at a pH within the range from about 6.5 to about 11 in the presence of an added catalytically active manganese compound in an amount sufficient to improve the selectivity of the delignification and increase the rate of delignification, the manganese compound being added before dissolution of approximately 10% of the lignin content of the starting lignocellulosic material.
Claim 14
Dependent Claim
16 words
A process according to claim 12, in which all of the manganese compound is added initially.
Claim 15
Dependent Claim
20 words
A process according to claim 12, in which the manganese compound is added incrementally in the course of the delignification.
Claim 16
Dependent Claim
20 words
A process according to claim 12, in which the manganese compound is added continuously in the course of the delignification.
Claim 17
Dependent Claim
25 words
A process according to claim 12, in which the manganese compound is impregnated into the lignocellulosic material prior to the delignification with oxygen and alkali.
Claim 18
Dependent Claim
16 words
A process according to claim 12, in which the manganese compound is a bivalent manganous compound.
Claim 19
Dependent Claim
52 words
A process according to claim 17, in which the manganous compound is selected from the group consisting of manganous oxide, manganous chloride, manganous bromide, manganous hydroxide, manganous nitrate, manganous sulfate, manganous carbonate, manganous phosphate, manganous acetate, manganous formate, manganous oxalate, and complex salts of manganous ion with chelating inorganic and organic acids.
Claim 20
Dependent Claim
36 words
A process according to claim 12, wherein the manganese compound is added in an amount within the range from about 0.001 to about 2% by weight Mn based on the dry weight of the lignocellulosic material.
Claim 21
Dependent Claim
29 words
A process according to claim 1, in which the lignocellulosic material prior to the delignification is washed to remove copper, cobalt and iron which catalyze the degradation of carbohydrates.
Claim 22
Dependent Claim
25 words
A process according to claim 20, wherein the lignocellulosic material prior to the delignification is washed with an aqueous solution comprising a metal complexing agent.
Claim 23
Dependent Claim
15 words
A process according to claim 20, wherein the lignocellulosic material is washed with hot water.
Claim 24
Dependent Claim
20 words
A process according to claim 20 wherein the lignocellulosic material is washed with an aqueous acidic solution comprising an acid.
Claim 25
Dependent Claim
35 words
A process according to claim 20 wherein the lignocellulosic material is washed with an aqueous alkaline solution comprising at least one alkali selected from the group consisting of sodium carbonate, sodium bicarbonate and sodium hydroxide
Claim 26
Dependent Claim
21 words
A process according to claim 20, wherein the lignocellulosic material is washed with a waste liquor from the oxygen-alkali delignification process.
Claim 27
Dependent Claim
28 words
A process according to claim 20, wherein the lignocellulosic material is washed with a member selected from the group consisting of water and acidic and alkaline aqueous solutions.
Claim 28
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 29
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 30
Dependent Claim
25 words
A process according to claim 1, wherein the delignification is carried out at a temperature within the range from about 80° to about 160° C.
Claim 31
Dependent Claim
40 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 80° to about 150° C during the delignification.
Claim 32
Dependent Claim
17 words
A process according to claim 1, wherein a magnesium compound is added as a cellulose degradation inhibitor.
Claim 33
Dependent Claim
34 words
A process according to claim 1, in which the amount of carbon monoxide is maintained within said range by delignification at a temperature within the range from about 90° C to about 150° C.
Claim 34
Dependent Claim
29 words
A process according to claim 32, in which exothermic heat of reaction is carried off by flowing a gas through a bed of the lignocellulosic material during the delignification.
Claim 35
Dependent Claim
20 words
A process according to claim 33, in which the gas is flowed countercurrently to a flow of the lignocellulosic material.
Claim 36
Dependent Claim
21 words
A process according to claim 33, in which the temperature of the gas is maintained below the temperature of the delignification.
Claim 37
Dependent Claim
36 words
A process according to claim 33, in which the partial pressure of water vapor in the gas introduced into the bed is maintained below the partial pressure of water vapor in the gas in the bed.
Claim 38
Dependent Claim
25 words
A process according to claim 33, in which the oxygen gas and carbon monoxide are removed from the delignification, cooled and recycled to the delignification.
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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) | 1980-09-26 | 1981-03-28 | 1981-09-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-09-26 | 1985-03-28 | 1985-09-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-09-26 | 1989-03-28 | 1989-09-27 | $7700.00 | Window Closed / Lapsed |