Study of Influence of atmosphere of Thermal Decomposition reaction of guarana seed residue aiming the torrefaction process
Janainna Chaves Pereira1; Henrique Real Guimarães1; Katia Tannous1
1 University of Campinas
doi:10.20906/CPS/COB-2015-1207
Resumo
The aim of this work was to study the Influence of atmosphere of thermal decomposition reaction of guarana seed residue aiming the torrefaction process by non-isothermal thermogravimetry. The selected biomass is an agroindustrial raw material from the production of guarana extract. The experiments were carried out in a thermogravimetric analyzer submitting 10 mg of particles of 250 µm using nitrogen and synthetic air atmospheres. The samples were heated from room temperature to 900 °C at a heating rate of 15 °C.min-1 and gas flow rate of 50 mL.min-1. The TG/DTG results indicate two regions of the biomass thermal behavior. In both cases, the first region (room temperature to 150 °C) was related to the drying step and the second region comprehended the thermal decomposition of main components (hemicellulose, cellulose and lignin). For the last region, it was observed that up to 370oC, the decompositions were similar. Between 370°C and 650°C in an oxidizing atmosphere, the biomass residue presented oxidative decomposition reactions characterized by a distinct shoulder. The residual solid was 24.56 % w/w and 6.51 % w/w for inert and oxidizing atmosphere, respectively. In conclusion, for torrefaction process effects would not be significant differences in the thermal decomposition of biomass between the atmospheres used, considering the temperature range of 200oC-350oC. An additional study was the estimation of the kinetic parameters for each atmosphere using the independent parallel reactions scheme. For the thermal decomposition were assumed three and six reactions related to in inert atmosphere and synthetic air, respectively. The activation energies were related for the first three reactions higher in synthetic air than nitrogen, due to the increasing of temperature promoted by the oxidizing reactions of the volatile released.
Palavras-chave: Paullinia cupana; thermogravimetry; thermal decomposition