Processes for producing lignin-coated hydrophobic cellulose, and compositions and products produced therefrom

Abstract

Processes disclosed are capable of converting biomass into high-crystallinity, hydrophobic cellulose. In some variations, the process includes fractionating biomass with an acid (such as sulfur dioxide), a solvent (such as ethanol), and water, to generate cellulose-rich solids and a liquid containing hemicellulose and lignin; and depositing lignin onto cellulose fibers to produce lignin-coated cellulose materials (such as dissolving pulp). The crystallinity of the cellulose material may be 80% or higher, translating into good reinforcing properties for composites. Optionally, sugars derived from amorphous cellulose and hemicellulose may be separately fermented, such as to monomers for various polymers. These polymers may be combined with the hydrophobic cellulose to form completely renewable composites.

What is claimed is: 
     
         1 . A process for producing a lignin-coated cellulose material, said process comprising:
 (a) providing a lignocellulosic biomass feedstock;   (b) fractionating said feedstock in the presence of an acid, a solvent for lignin, and water, to generate cellulose-rich solids and a liquid containing hemicellulose and lignin;   (c) depositing at least some of said lignin, from said liquid, onto a surface of said cellulose-rich solids to generate a lignin-coated cellulose material;   (d) optionally mechanically treating said lignin-coated cellulose material; and   (e) recovering said lignin-coated cellulose material,   wherein cellulose crystallinity of said lignin-coated cellulose material is at least 60%, and wherein said lignin-coated cellulose material is at least partially hydrophobic.   
     
     
         2 . The process of  claim 1 , wherein said acid is selected from the group consisting of sulfur dioxide, sulfurous acid, sulfur trioxide, sulfuric acid, lignosulfonic acid, and combinations thereof. 
     
     
         3 . The process of  claim 2 , wherein said acid is sulfur dioxide. 
     
     
         4 . The process of  claim 3 , wherein sulfur dioxide concentration in step (b) is from about 12 wt % to about 30 wt %. 
     
     
         5 . The process of  claim 1 , wherein fractionation temperature in step (b) is from about 140° C. to about 170° C. 
     
     
         6 . The process of  claim 1 , wherein fractionation time in step (b) is from about 1 hour to about 2 hours. 
     
     
         7 . The process of  claim 1 , wherein step (d) is performed and wherein steps (c) and (d) are integrated. 
     
     
         8 . The process of  claim 1 , wherein step (d) is performed and wherein said lignin-coated cellulose material is treated with a total mechanical energy of less than about 500 kilowatt-hours per ton of said lignin-coated cellulose material. 
     
     
         9 . The process of  claim 1 , wherein said process further comprises treatment of said lignin-coated cellulose material with one or more enzymes. 
     
     
         10 . The process of  claim 1 , wherein said process further comprises treatment of said lignin-coated cellulose material with one or more acids. 
     
     
         11 . The process of  claim 10 , wherein said one or more acids are selected from the group consisting of sulfur dioxide, sulfurous acid, lignosulfonic acid, acetic acid, formic acid, and combinations thereof. 
     
     
         12 . The process of  claim 1 , wherein said process further comprises treatment of said lignin-coated cellulose material with heat. 
     
     
         13 . The process of  claim 1 , wherein said cellulose crystallinity of said lignin-coated cellulose material is at least 70%. 
     
     
         14 . The process of  claim 13 , wherein said cellulose crystallinity of said lignin-coated cellulose material is at least 80%. 
     
     
         15 . The process of  claim 14 , wherein said cellulose crystallinity of said lignin-coated cellulose material is at least 85%. 
     
     
         16 . The process of  claim 1 , wherein said lignin-coated cellulose material includes, or is characterized as, lignin-coated dissolving pulp. 
     
     
         17 . The process of  claim 1 , wherein said lignin-coated cellulose material includes, or is characterized as, lignin-coated fibrillated cellulose. 
     
     
         18 . The process of  claim 1 , wherein said lignin-coated cellulose material includes, or is characterized as, lignin-coated microcrystalline cellulose. 
     
     
         19 . The process of  claim 1 , wherein said lignin-coated cellulose material includes, or is characterized as, lignin-coated nanocellulose. 
     
     
         20 . The process of  claim 1 , wherein said lignin-coated cellulose material is characterized by an average degree of polymerization from about 100 to about 1500. 
     
     
         21 . The process of  claim 1 , said process further comprising chemically modifying said lignin to increase hydrophobicity of said lignin-coated cellulose material. 
     
     
         22 . The process of  claim 1 , said process further comprising recovering, combusting, or further treating said lignin that does not deposit onto said cellulose-rich solids during step (c). 
     
     
         23 . The process of  claim 1 , said process further comprising chemically converting said lignin-coated cellulose material to one or more lignin-coated cellulose derivatives. 
     
     
         24 . The process of  claim 23 , wherein said lignin-coated cellulose derivatives are selected from the group consisting of cellulose esters, cellulose ethers, cellulose ether esters, alkylated cellulose compounds, cross-linked cellulose compounds, acid-functionalized cellulose compounds, base-functionalized cellulose compounds, and combinations thereof. 
     
     
         25 . The process of  claim 1 , said process further comprising hydrolyzing amorphous cellulose, contained in said lignocellulosic biomass feedstock, into glucose, and optionally fermenting said glucose to a fermentation product. 
     
     
         26 . The process of  claim 1 , said process further comprising recovering, fermenting, or further treating hemicellulosic sugars derived from said hemicellulose. 
     
     
         27 . The process of  claim 26 , said process further comprising fermenting said hemicellulosic sugars to produce a monomer or precursor thereof; polymerizing said monomer to produce a polymer; and combining said polymer and said lignin-coated cellulose material to form a polymer-cellulose composite. 
     
     
         28 . A hydrophobic cellulose composition with a cellulose crystallinity of about 70% or greater, wherein said hydrophobic cellulose composition contains cellulose particles having a surface concentration of lignin that is greater than a bulk concentration of lignin. 
     
     
         29 . The hydrophobic cellulose composition of  claim 28 , wherein said cellulose crystallinity is about 75% or greater. 
     
     
         30 . The hydrophobic cellulose composition of  claim 29 , wherein said cellulose crystallinity is about 80% or greater. 
     
     
         31 . The hydrophobic cellulose composition of  claim 30 , wherein said cellulose crystallinity is about 85% or greater. 
     
     
         32 . The hydrophobic cellulose composition of  claim 28 , wherein said composition further comprises sulfur. 
     
     
         33 . The hydrophobic cellulose composition of  claim 28 , wherein said composition is characterized by an average cellulose degree of polymerization from about 100 to about 1500. 
     
     
         34 . The hydrophobic cellulose composition of  claim 28 , wherein said composition is characterized by a cellulose degree of polymerization distribution having a single peak. 
     
     
         35 . The hydrophobic cellulose composition of  claim 28 , wherein said composition is produced by a process comprising:
 (a) providing a lignocellulosic biomass feedstock;   (b) fractionating said feedstock in the presence of an acid, a solvent for lignin, and water, to generate cellulose-rich solids and a liquid containing hemicellulose and lignin;   (c) depositing at least some of said lignin, from said liquid, onto a surface of said cellulose-rich solids to generate a lignin-coated cellulose material;   (d) optionally mechanically treating said lignin-coated cellulose material; and   (e) recovering said lignin-coated cellulose material as said composition,   wherein said lignin-coated cellulose material is at least partially hydrophobic.   
     
     
         36 . A cellulose-containing product comprising the hydrophobic cellulose composition of  claim 28 . 
     
     
         37 . The cellulose-containing product of  claim 36 , wherein said cellulose-containing product is selected from the group consisting of a structural object, a foam, an aerogel, a polymer composite, a carbon composite, a film, a coating, a coating precursor, a current or voltage carrier, a filter, a membrane, a catalyst, a catalyst substrate, a coating additive, a paint additive, an adhesive additive, a cement additive, a paper coating, a thickening agent, a rheological modifier, an additive for a drilling fluid, and combinations or derivatives thereof. 
     
     
         38 . The cellulose-containing product of  claim 37 , wherein said cellulose-containing product is a moisture-barrier pressed pulp product.