Abstract
Various physical, chemical, and structural changes were assessed that occur during torrefaction of cellulose were assessed, including water uptake, tensile strength, FTIR, TG-MS & H-NMR spectra, and glucose yield. The water uptake capacity is positively correlated to glucose yield which suggests that water-substrate interaction may be a primary driver of the hydrolysis process. The wet-tensile strength of fibrous cellulose increases with torrefaction and is negatively correlated to glucose yield. The hydrogen bonding capacity of torrefied samples is likely to be impacted by the dehydration reaction induced by torrefaction, as indicated by discernible changes in both the FTIR spectra and solid-state H-NMR spectra. The emergence of a peak at 1724 cm-1 in the spectrum of torrefied cellulose is also suggestive of an inhibitory compound containing a carbonyl group. FTIR spectra show evidence of the removal of the suspected inhibitor by alkaline pretreatment. Additionally, with an increase in torrefaction severity, the specific surface area decreases. These results, taken together, suggest that decreased hydrolysis efficiency from torrefaction is a function of the combined effects on surface area, surface composition and chemistry, and H-bonding network.