Methods for preparing thermally stable lignin fractions
First Claim
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1. A lignin composition comprising lignin, wherein the composition is characterized by a consistent glass transition temperature (Tg) as determined by two consecutive differential scanning calorimetry (DSC) runs of the same lignin portion according to DIN 53765-1994, wherein a first Tg is measured during a first DSC run, a second Tg is measured during a second DSC run, and the difference between the first Tg and the second Tg is less than 10°
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Abstract
The present invention relates to fractions of high purity lignin which are thermally stable, and to methods of producing said fractions from lignocellulosic material.
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Citations
20 Claims
- 1. A lignin composition comprising lignin, wherein the composition is characterized by a consistent glass transition temperature (Tg) as determined by two consecutive differential scanning calorimetry (DSC) runs of the same lignin portion according to DIN 53765-1994, wherein a first Tg is measured during a first DSC run, a second Tg is measured during a second DSC run, and the difference between the first Tg and the second Tg is less than 10°
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11. A method for fractionating lignin, the method comprising:
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(i) contacting a sample comprising solid lignin and less than 1% weight/weight carbohydrates with an organic solvent to form a biphasic mixture, wherein the mixture comprises; (a) a remainder solid comprising a first fraction of the lignin, wherein the first fraction is designated as a solvent-insoluble lignin fraction; and (b) a liquid solution comprising the solvent and a second fraction of the lignin, wherein the second fraction is designated as a solvent-soluble lignin fraction; and (ii) spatially separating the solvent-insoluble lignin fraction from the solvent-soluble lignin fraction; wherein the solvent-insoluble lignin fraction and the solvent-soluble lignin fraction have different glass transition temperatures. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19)
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20. A method for producing high purity lignin from a biomass, comprising:
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(i) removing hemicellulose sugars from the biomass, thereby obtaining a lignin-containing remainder;
wherein the lignin-containing remainder comprises lignin and cellulose;(ii) contacting the lignin-containing remainder with a lignin extraction solution to produce a lignin extract and a cellulosic remainder;
wherein the lignin extraction solution comprises a limited-solubility solvent, an organic acid, and water, wherein the limited-solubility solvent and the water form an organic phase and an aqueous phase; and(iii) separating the lignin extract from the cellulosic remainder;
wherein the lignin extract comprises lignin dissolved in the limited-solubility solvent;and further comprising one, two, three or four additional step(s) selected from; (iv) distilling or flash evaporating the lignin extract, thereby removing the bulk of the limited-solubility solvent from the lignin extract to obtain a solid lignin; (v) heating the solid lignin, thereby removing trace limited-solubility solvent or water from the solid lignin; (vi) applying a vacuum to the solid lignin, thereby removing trace limited-solubility solvent or water from the solid lignin; and (vii) contacting the solid lignin with an organic solvent to form a biphasic mixture, wherein the mixture comprises; (a) a remainder solid comprising a first fraction of the lignin, wherein the first fraction is designated as a solvent-insoluble lignin fraction; and (b) a liquid solution comprising the solvent and a second fraction of the lignin, wherein the second fraction is designated as a solvent-soluble lignin fraction.
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Specification