Industrial-scale steam explosion pretreatment of sugarcane straw for enzymatic hydrolysis of cellulose for production of second generation ethanol and value-added products

Steam explosion at 180, 190 and 200 °C for 15 min was applied to sugarcane straw in an industrial sugar/ethanol reactor (2.5 m3). The pretreated straw was delignificated by sodium hydroxide and hydrolyzed with cellulases, or submitted directly to enzymatic hydrolysis after the pretreatment. The pretreatments led to remarkable hemicellulose solubilization, with the maximum (92.7%) for pretreatment performed at 200 °C. Alkaline treatment of the pretreated materials led to lignin solubilization of 86.7% at 180 °C, and only to 81.3% in the material pretreated at 200 °C. All pretreatment conditions led to high hydrolysis conversion of cellulose, with the maximum (80.0%) achieved at 200 °C. Delignification increase the enzymatic conversion (from 58.8% in the cellulignin to 85.1% in the delignificated pulp) of the material pretreated at 180 °C, but for the material pretreated at 190 °C, the improvement was less remarkable, while for the pretreated at 200 °C the hydrolysis conversion decreased after the alkaline treatment.