Tuesday, April 30, 2013
Exhibit Hall
Second generation ethanol demands studies on scale-up. This work deals with the dilute acid pretreatment of sugarcane bagasse followed by delignification. Experiments carried out in a 350-L stainless-steel stirred reactor, with 1.0% (w/v) H2SO4 at 120 °C for 20 min, promoted a 75.6% hemicellulose solubilization in comparison with 45.5% hemicelluloses solubilized using 1.5% H3PO4 (w/v) at 120ºC by 20 min. Both pretreatments did not solubilized significant amounts of lignin, being condensation reaction an explanation for this fact. Thermoporometry for the “in natura” and pretreated biomass samples confirmed the increase in the pore quantity in the cellulose structure, promoted by both acidic pretreatments. Aiming the data collection for the delignification process scale-up, preliminary delignification reactions of H3PO4-treated bagasse, carried-out in a 2-L reactor, showed higher lignin solubilization when the severity is increased. Enzymatic hydrolysis assays of these materials resulted in 22-30% sugar conversion, showed that the cellulose conversion was difficulted due to the high lignin content, still remained in the pretreated materials. With an additional alkaline delignification step (1.5% NaOH, 1:15 solid to liquid ratio, 1 h at 100oC ), enzymatic conversion rised 56.5% [Acknowledgements due to CNPq, FAPESP and CTBE]