Decomposition of Cellulose and Glucose in Hot-Compressed Water under Catalyst-Free Conditions.

Cellulose, a major component of woody biomass, was reacted in hot-compressed water under catalyst-free conditions at different reaction temperatures from 200 to 350°C. The product distribution was analyzed at different temperatures and/or holding times. A simplified reaction scheme is proposed, in which char-like residues are produced from cellulose through water-soluble products and oils, as intermediates. Experiments with glucose and cellulose feedstock resulted in the same product distribution, suggesting that cellulose decomposition starts with a first hydrolysis step. Levoglucosan and 5-(hydroxymethyl)furfural (HMF) were also detected. The role of alkali catalysts in cellulose liquefaction is discussed.