Torrefaction of cellulose, hemicelluloses and lignin extracted from woody and agricultural biomass in TGA-GC/MS: Linking production profiles of volatile species to biomass type and macromolecular composition

Abstract : The production of volatile species in torrefaction of cellulose, hemicellulose and lignin extracted from woody and agricultural biomass was quantified as a function of temperature. The novel coupling of TGA to GC/MS through a heated storage loop system allowed sampling volatile species released at 11 different temperatures in a single torrefaction experiment between 200 and 300 °C, at 3 °C.min−1. The results showed that the use of extracted fractions obtained from different biomass samples led to the detection of a higher number of species (23) than in previous studies with commercial compounds, obtaining a higher degree of detail in the characterization of the production of volatile species in torrefaction. Volatile species were generally released in this study from lower temperatures than those previously reported for commercial compounds. This may be due to the better preservation of cellulose, hemicellulose and lignin properties in extracted fractions thanks to the optimized extraction procedure. Volatile species production profiles were assessed based on the formation mechanisms proposed in the literature and the production of polysaccharide-based fractions was shown to be correlated to their sugar composition. Finally, production profiles allow identifying the temperature range to enhance the production of a given volatile species in torrefaction.