Biomass thermal behavior under different atmosphere: combustion, pyrolysis (N2) and typical oxy-fuel combustion (60 and 80% CO2) were investigated by thermal analysis (TG/DTG and DTA). Other techniques such as X-Ray, Fourier Transformed Infrared (FTIR), Wettability, Scanning Electron Microscopy (SEM) and Inductive Couple Plasma - Optical Emission Spectrometer (ICP-OES) were also used to characterize the samples. Five Brazilian in natura biomass samples (sugarcane bagasse, pine sawdust, coffee and rice husk, and tucumã seed) were used to assess their possible application as bioenergy source. TG/DTG and DTA curves identify the main thermal degradation steps, which correspond to hemicelluloses, cellulose and lignin content. X-Ray showed crystallinity index (CI) for the biomass samples between 53 and 70%, confirming both crystalline and amorphous regions. The morphology revealed the main differences in the sample structures. The HHV ranged from 15 to 21 MJ kg-1. FTIR spectroscopy evaluated mainly the presence oxygen, carbon and hydrogen. Wettability for some samples showed a superhydrophilic character, whereas for others a hydrophobic character. Metal composition determination by ICP-OES identified the main inorganic materials present in biomasses. All biomass exhibited good characteristics to be used as bioenergy. However, tucumã seeds showed the best properties, that is, high HHV, low moisture contents and ash, high contents of carbon and hydrogen, large oiliness level and hydrophobic character.

Keywords: Biomass characterization, conversion process, functional groups, metal composition, morphology, thermal degradation.