1 A General Mathematical Model of Biomass Devolatilization Note 1. Lumped kinetic models of cellulose, hemicellulose and lignin.

Main goal of this work, organized in two different notes, is to characterize the pyrolysis and gasification of biomasses with a suitable description of the production of gas and tar components. The chemical characterization of the released species is a relevant aspect towards a consistent design and optimization of different process units where pyrolysis and partial oxidation reactions take place along with the complex physical processes involved in the thermal degradation of biomasses. Biomasses are typically constituted by cellulose, hemicellulose and lignin. Conventional empirical kinetic models are simply derived both on the basis of experimental data and on the basis of semi-detailed kinetic models of devolatilization of the three reference components. The lumped mechanism discussed in this work includes about 15 apparent reactions involving 30 lumped or real species. Together with the formation of CO, CO2 and H2O, the model describes the relevant formation of levoglucosan, hydroxyacethaldeyde, acetic acid, glyoxal and furfural species from the pyrolysis of cellulose. Similarly, xylose and other oxygenated species characterize the degradation of hemicellulose. Different reference components distinguish softwood and hardwood lignin characteristics and they allow to describe also the release of sinapyl and coumaryl derivatives. The successive evolution in the gas phase of the released tar and gas species is analysed in the second note of this work. 1