Refining cellulose in a solvent for production of nanocellulose materials

Abstract

Cellulose precursor materials may be refined (e.g., fibrillated) in an ethanol medium, or other solvent medium, instead of water. Following refining, the solvent may be removed and recycled prior to incorporation into another material, or optionally, following such incorporation. The solvent may assist the incorporation of nanocellulose into another material (e.g., a polymer) for a composite, for example. In some variations, a process comprises fractionating a biomass 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; mechanically treating the cellulose-rich solids, in the presence of a refining solvent, to form cellulose fibrils and/or cellulose crystals, thereby generating a nanocellulose material; recovering and recycling the refining solvent; and recovering the nanocellulose material or incorporating the nanocellulose material into a composite material.

What is claimed is: 
     
         1 . A process for producing a nanocellulose 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) mechanically treating said cellulose-rich solids, in the presence of a refining solvent, to form cellulose fibrils and/or cellulose crystals, thereby generating a nanocellulose material;   (d) recovering and recycling said refining solvent; and   (e) recovering said nanocellulose material.   
     
     
         2 . The process of  claim 1 , wherein said refining solvent is a non-polar solvent, a polar aprotic solvent, a polar protic solvent, or a combination thereof. 
     
     
         3 . The process of  claim 1 , wherein said refining solvent is selected from the group consisting of alcohols, diols, organic acids, inorganic acids, fatty acids, and combinations thereof. 
     
     
         4 . The process of  claim 3 , wherein said refining solvent comprises ethanol. 
     
     
         5 . The process of  claim 3 , wherein said refining solvent is ethanol. 
     
     
         6 . The process of  claim 1 , wherein said refining solvent is a biomass-derived solvent. 
     
     
         7 . The process of  claim 6 , wherein said biomass-derived solvent is derived from lignin. 
     
     
         8 . The process of  claim 1 , wherein said refining solvent is an ionic liquid. 
     
     
         9 . The process of  claim 1 , wherein said refining solvent further includes water. 
     
     
         10 . The process of  claim 1 , wherein said refining solvent completely dissolves said cellulose-rich solids. 
     
     
         11 . The process of  claim 1 , wherein said refining solvent completely suspends but does not dissolve said cellulose-rich solids. 
     
     
         12 . The process of  claim 1 , wherein said refining solvent partially suspends and partially dissolves said cellulose-rich solids. 
     
     
         13 . The process of  claim 1 , wherein said refining solvent participates in chemical reactions involving said cellulose-rich solids. 
     
     
         14 . The process of  claim 1 , wherein said refining solvent participates in chemical reactions involving said cellulose fibrils and/or cellulose crystals. 
     
     
         15 . The process of  claim 1 , wherein said refining solvent chemically, physically, or electrochemically modifies a cellulose surface. 
     
     
         16 . The process of  claim 1 , wherein step (e) is conducted prior to step (d). 
     
     
         17 . The process of  claim 1 , wherein steps (d) and (e) are integrated. 
     
     
         18 . The process of  claim 1 , wherein said nanocellulose material is incorporated into a composite material. 
     
     
         19 . A process for producing a composite 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) mechanically treating said cellulose-rich solids, in the presence of a refining solvent, to form cellulose fibrils and/or cellulose crystals, thereby generating a nanocellulose material;   (d) incorporating said nanocellulose material, dissolved or suspended in said refining solvent, into a composite material containing a polymer and/or a carbon-containing compound;   (e) recovering said refining solvent from said composite material; and   (f) optionally recycling said refining solvent.   
     
     
         20 . A composite material 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) mechanically treating said cellulose-rich solids, in the presence of a refining solvent, to form cellulose fibrils and/or cellulose crystals, thereby generating a nanocellulose material;   (d) incorporating said nanocellulose material, dissolved or suspended in said refining solvent, into a composite material containing a polymer and/or a carbon-containing compound;   (e) recovering said refining solvent from said composite material; and   (f) optionally recycling said refining solvent.