Abstract: The present invention generally provides methods of improving lignin separation during biomass fractionation with an acid to release sugars and a solvent for lignin (such as ethanol). In some embodiments, a digestor is employed to fractionating a feedstock in the presence of a solvent for lignin, sulfur dioxide, and water, to produce a liquor containing hemicellulose, cellulose-rich solids, and lignin. A solid additive is added to the digestor, wherein the solid additive combines with at least a portion of the lignin. Then a mixture of lignin and the solid additive is separated from the liquor, prior to hemicellulose recovery. Optionally, a solid additive may also be introduced to a hydrolysis reactor for converting hemicellulose oligomers to monomers, to improve separation of acid-catalyzed lignin. In some embodiments, the solid additive is gypsum or a gypsum/lignin mixture.

Abstract: The present invention generally provides methods of improving lignin separation during biomass fractionation with an acid to release sugars and a solvent for lignin (such as ethanol). In some embodiments, a digestor is employed to fractionating a feedstock in the presence of a solvent for lignin, sulfur dioxide, and water, to produce a liquor containing hemicellulose, cellulose-rich solids, and lignin. A solid additive is added to the digestor, wherein the solid additive combines with at least a portion of the lignin. Then a mixture of lignin and the solid additive is separated from the liquor, prior to hemicellulose recovery. Optionally, a solid additive may also be introduced to a hydrolysis reactor for converting hemicellulose oligomers to monomers, to improve separation of acid-catalyzed lignin. In some embodiments, the solid additive is gypsum or a gypsum/lignin mixture.

Abstract: What is disclosed is a biorefining process and system including the steps of extracting, hydrolyzing, and/or digesting a lignocellulosic biomass feedstock, or a component thereof, with a liquid or vapor solution comprising reactant sulfur dioxide or a derivative thereof, to generate cellulose-rich solids and an intermediate liquid stream; combusting or gasifying a sulfur-containing fuel to generate heat and an exhaust gas stream comprising produced sulfur dioxide; contacting the exhaust gas stream with the intermediate liquid stream to dissolve the produced sulfur dioxide into the intermediate liquid stream; and then recycling the intermediate liquid stream to reuse the produced sulfur dioxide as the reactant sulfur dioxide. The sulfur-containing fuel may be sulfonated lignin generated by reaction of lignin (derived from the feedstock) with the reactant sulfur dioxide, resulting in a closed loop for sulfur dioxide in the biorefinery.

Abstract: The present invention generally provides methods of improving lignin separation during biomass fractionation with an acid to release sugars and a solvent for lignin (such as ethanol). In some embodiments, a digestor is employed to fractionating a feedstock in the presence of a solvent for lignin, sulfur dioxide, and water, to produce a liquor containing hemicellulose, cellulose-rich solids, and lignin. A solid additive is added to the digestor, wherein the solid additive combines with at least a portion of the lignin. Then a mixture of lignin and the solid additive is separated from the liquor, prior to hemicellulose recovery. Optionally, a solid additive may also be introduced to a hydrolysis reactor for converting hemicellulose oligomers to monomers, to improve separation of acid-catalyzed lignin. In some embodiments, the solid additive is gypsum or a gypsum/lignin mixture.

Abstract: Variations of this invention reduce or avoid lignin precipitation during acidic hydrolysis of biomass hydrolysates (such as hemicellulose-containing liquid extracts). Net acid usage and byproduct salt formation are significantly reduced. In some embodiments, hemicellulosic oligomers are hydrolyzed, in the presence of sulfur dioxide, to produce fermentable hemicellulosic sugars; the process comprising recovering and recycling at least a portion of the sulfur dioxide, wherein at least a portion of the sulfur dioxide reacts with the lignin to produce hydrophilic sulfonated lignin that has less tendency to precipitate or stick.

Abstract: The present invention generally provides methods of improving lignin separation during lignocellulosic biorefining, comprising the steps of (i) catalyzing fractionation or hydrolysis with an acid to release sugars into an acidified solution containing lignin, (ii) neutralizing the acidified solution with a base to form a salt in a neutralized solution; (iii) in a separation unit, separating the salt and the lignin, each in free or combined form, from the neutralized solution; and then (iv) recycling a portion of the salt and optionally a portion of the lignin to step (i) to combine, physically or chemically, with the lignin, to improve lignin separation in the separation unit. In certain embodiments, the acid is a sulfur-containing acid and the base is lime, forming gypsum which is then recycled, in part, to the hydrolysis reactor.