Hydrothermal dissolution of mixed southern hardwoods

A hydrothermal dissolution profile of wood components cellulose, hemicelluloses, and lignin of hardwood during autohydrolysis for 100 min at temperatures from 130 to 170 degrees C in a modified accelerated solid extraction system (Dionex ASE-100) is described. The content of cellulose, hemicelluloses, lignin, acetyl, and uronic acid groups remaining in the extracted wood were determined. The extract was analyzed for oligosaccharides and monosaccharides, lignin, acetic acid, uronic acid, furfural, and hydroxymethylfurfural. Xylo-oligomers are the predominant component in the extract at temperatures higher than 150 degrees C. At temperatures higher than 160 degrees C, small amounts of furfural and hydroxymethylfurfural are generated. Most of the arabinan and galactan are removed from the wood at 160 degrees C. The xylan remaining in the wood is acetylated at the same degree as in the original wood. In the extract, the ratio of acetyl groups bound to xylooligosaccharides decreases with increasing temperature. The content of uronic acid groups found in the extract obtained after autohydrolysis at T >= 150 degrees C is significantly smaller than that calculated from the decrease in uronic content of the wood.